Assessing Heat-Driven 4D Printed Finger Actuators with Conductive Wires: A Parametric Analysis

Assessing Heat-Driven 4D Printed Finger Actuators with Conductive Wires: A Parametric Analysis | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Assessing Heat-Driven 4D Printed Finger Actuators with Conductive Wires: A Parametric Analysis Kushendarsyah Saptaji, Azhari Tumada, Octarina Adiati Juniasih, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7060696/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract 4D printing, utilizing the fourth dimension of time, allows for the creation of time-dependent objects that can morph and adapt. This capability has shown great potential in soft robotics, particularly in developing soft actuators for adaptive movement. Heat-sensitive shape-memory polymers are a key component in this process, enabling programmed shape changes in response to temperature change. In this study, the heat induced wire is used as the heat stimulus for the 4D printed self-actuator finger. The objectives are to observe the effect of current, temperature, and wire arrangement to the deflection of self-actuator finger, and to obtain the optimum parameters for actuation. The deflection angle and the deflection radius are measured in this study to evaluate the finger performance aiming for a larger deflection angle and a smaller curvature radius. In addition, the effect of the fin on the deflection is also observed. An ANOVA method was used to statistically determine the significant effects of the current, temperature and wire arrangement and to obtain the optimum parameters. Result shows that current, temperature, and wire arrangement all have significant impacts on deflection. The 5.2 Ampere current offers better deflection results compared to 4 Ampere or lower. When the temperature exceeds the PLA's glass transition temperature in the wire, the specimen deflects according to the programmed direction. Additionally, utilizing 3 nitinol wires resulted in greater deflection than using 2. The optimal parameters for maximum deflection are 3 power supplies, 3 nitinol wire, and 5.2 amperes. Furthermore, a design with fins achieves better deflection compared to a design without fins. 4D printing Shape memory polymers Finger gripper nitinol wire heat conduction wire deflection angle deflection radius Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 Figure 15 Figure 16 Figure 17 Figure 18 Figure 19 1. Introduction Four-dimensional (4D) printing has emerged as a transformative extension of three-dimensional (3D) printing, enabling the fabrication of dynamic shape shifting structures [ 1 ]. In general, 3D printing is an additive manufacturing (AM) technique in which materials are deposited layer by layer to create three-dimensional objects such as eyeglasses, custom prosthetic devices, and dental implants [ 2 ], [ 3 ]. This 3D printing method enables the fabrication of personalized models from volumetric digital design used for preoperative planning and constructing personalized prostheses for patients [ 4 ]–[ 6 ]. It offers the advantage of producing personalized and less post-processing compared to the conventional manufacturing. The same methods used in 3D printing are applied in 4D printing, often referred to shape-morphing systems [ 7 ], [ 8 ]. With the integration of the fourth dimension, 4D printing further advances these capabilities by allowing printed structures to morph and adapt over time according to pre-programmed mechanisms [ 9 ]. The fourth dimension of 4D printing, on the other hand, is the time-dependent shape change that occurs after the printing, allowing the 3D shape that is produced to transform into new shapes in reaction to external stimuli such as heat, light, humidity, water, voltage, and pH [ 10 ]–[ 12 ]. Thus, shape memory materials employed in 4D printing are considered programmable [ 13 ]–[ 15 ]. The applications of 4D print have gathered into various fields, such as medical, aerospace, and soft robotics. In the field of robotics, 4D-printed actuators have attracted significant research interest due to their programmable movement [ 16 ], [ 17 ]. An actuator plays a critical role in robotics by mimicking the motor-response mechanism that enables motion in response to specific commands [ 18 ], [ 19 ]. However, conventional actuators, typically made from rigid material which face limitations in flexibility and adaptability. Their inability to handle complex shapes or dynamic environments limits their application in specific applications [ 20 ]. This limitation has driven the development of soft robotics, which seeks to address these challenges by employing materials such as elastomers and polymers that can deform significantly and return to their original shape [ 21 ]. Soft actuators, as a core element of soft robotics, have shown promise in applications such as prosthetics, medical devices, and automation systems [ 22 ], [ 23 ]. Compared to rigid actuators, soft actuators offer enhanced range of motion, safer interaction with delicate objects, lightweight design, and higher power-to-weight ratio [ 24 ]. Moreover, Kim et. al. (2019) mentioned soft actuators can withstand large strains without permanent damage, which contributes to greater durability and functional lifespan [ 25 ]. The soft actuators work by converting input stimuli into mechanical motion. They are classified based on the type of stimulus required such as electroactive polymers rely on chemical signals, pneumatic [ 26 ] and hydraulic actuators use air or liquids, shape memory materials respond to heat, while others react to light, magnetic fields, or electric fields [ 27 ]. These actuators must meet demands for precision, speed, reversibility, and the ability to bend, extend, or twist, while delivering sufficient force. The choice of actuation mechanism significantly influences the size, weight, power requirements, sensing systems, and control systems of soft robotic devices [ 28 ]. Hence, actuator systems selection must be aligned with the targeted functionality and application needs. With 4D printing, which enables objects to morph over time in response to stimuli, the design challenge increases. The applications of actuations must account for material properties, geometrical effect, and external triggers to ensure reliable performance [ 29 ], [ 30 ]. One of the most common examples in the applications of 4D printing in soft robotics is in gripping mechanism. Grippers are essential components in various industries, particularly in automation and robotics, where they are used for handling, assembling, and manipulating objects [ 31 ], [ 32 ]. Conventional grippers often require complex mechanisms to adjust grips, which may reduce efficiency and increase failure rates. 4D-printed grippers overcome this by integrating smart materials capable of self-actuation. When stimulated (e.g., by heat), these materials deform in a pre-programmed manner, allowing the gripper to autonomously adapt to various object geometries [ 33 ], [ 34 ]. Beyond traditional automation, the concept of 4D-printed soft grippers can also be extended to smart packaging systems [ 35 ]. Smart packaging increasingly demands adaptive handling, secure sealing, and controlled release of products, all of which could benefit from soft gripper-inspired mechanisms. By integrating 4D-printed, heat-responsive soft grippers into packaging, it becomes possible to achieve automatic opening, closing, or repositioning functions in response to temperature changes. This approach combines the programmability and flexibility of soft grippers with the needs of modern packaging, enhancing product safety, reducing waste, and supporting sustainability efforts through more intelligent, responsive packaging designs [ 36 ]. The self-actuating gripper finger developed in this study has potential applications in smart manufacturing, medical devices, logistics, and operations in special environments. Its ability to respond to external stimuli without complex mechanical systems supports the development of flexible, efficient, and adaptive technologies. These characteristics align with Sustainable Development Goal (SDG) 9, which promotes innovation and the creation of resilient infrastructure for sustainable industrial advancement. Therefore, this research aims to bridge the gap in 4D printing by exploring the combined use of shape memory polymers (SMP), specific finger design and heat-conducting wire to create a self-actuating gripper finger. While SMPs have been studied extensively, their application in self-actuating grippers, especially when stimulated by heat-conducting wire, remains underexplored. According to problem stated, the objectives of this study are to observe the effect of current, temperature, and wire arrangement to the deflection of 4D self-actuator finger, to obtain the optimum parameters such as current, temperature, and wire arrangement as the input of heat stimulus to the 4D self-actuator finger based on the deflection angle and radius of the deflection curve. In addition, the effect of fin to the deflection of the 4D self-actuator finger is also explored. Furthermore, this paper will cover the methodology, result and discussion, and conclusion. 2. Methodology 2.1. Materials and Design In this experiment, the self-actuator finger was designed in order to represent one finger of the whole gripper. The self-actuator finger was fabricated using Fused Deposition Modeling (FDM) 3D Printer (Anycubic i3 Mega) with parameters shown in Table 1 . Polylactic acid (PLA) as the shape memory polymer (SMP) was used for the main part of the finger. The nickel-titanium (nitinol) wire with 1 mm diameter incorporated into the system as the heat conductive wire, and copper wire of 1 mm diameter used to transfer electricity into the nitinol wire. The general design and dimensions of the self-actuator finger is shown in Fig. 1 adapted from [ 37 ]. Table 1 Printing Parameter Parameters Value Printing Speed 50 mm/s Printing Pattern Line Printing thickness 0.2 mm Printing Temperature 205 o C Bed Temperature 60 o C Infill Density 60% 2.2. Experimental Setup In addition to the self-actuated soft robotic finger, the experimental setup consists of a digital power supply, a thermocouple for temperature measurement, and a laptop for data acquisition and control. The power supply used in this study is Digital Ways DW PS31505W with detailed specifications presented in Table 2 . In this study, a Nitinol wire, which is an alloy composed of nickel and titanium with shape memory properties, is integrated into the finger gripper to enable heat-induced actuation. Nitinol is widely recognized for its use in the space industry and has also been studied in the context of four-dimensional printing due to its ability to respond to thermal stimuli. A thermocouple is placed near the Nitinol wires to monitor the heating process in real time, while a laptop is used to record both temperature and deflection data during the experiments. Table 2 Power Supply Specification Specification Value Output Voltage 0–15 V Output Current 0–5 A Output Current 300 W Three experimental setups were proposed in this study to analyze two main parameters such as wire arrangement and current input. Each setup consists of a self-actuated specimen, a temperature sensor (thermocouple), Nitinol wires, copper wires, and a power supply system. The first setup uses two Nitinol wires; each connected to an individual power supply (Fig. 2 ). The second setup is similar to the first but incorporates one additional Nitinol wire and power supply (Fig. 3 ). The third setup also utilizes three Nitinol wires; however, it employs only a single power supply with a three-way current divider to distribute the current evenly among the wires (Fig. 4 ). Thermocouples were attached to each Nitinol wire across all setups to monitor temperature changes during actuation. These three configurations were used in a total of ten experiments, varying in wire arrangement and current levels, as summarized in Table 3 . Initially, the end part of the finger actuator was clamped using a vice clamp. The Nitinol wires were then activated by applying electric current to generate heat, which was transferred to the finger actuator. This thermal input was expected to induce deflection in the actuator. The heating process was maintained for five minutes, during which the temperature was recorded at one-minute interval. Prior to the experiment, the temperature sensors were calibrated using room temperature and boiling water to ensure accurate readings. The effects of the experimental parameters were evaluated based on deflection angle and deflection radius. The deflection angle was measured every minute, while the deflection radius was measured at the fifth minute, when the actuator had reached its final bending position. Table 3 Experiments List Experiment Setup Used Wire Arrangement Current (Ampere) Fin Number of Nitinol Wire Number of Power Supply 1 1 2 2 2 Facing Downward 2 2 2 4 3 2 2 5.2 4 2 3 3 2 5 3 3 4 6 3 3 5.2 7 3 3 1 4 8 3 1 5.2 9 2 3 3 5.2 Facing Upward 10 3 3 5.2 No Fin 2.3. Method of Measurement 2.3.1. Deflection Angle To measure the degree of deflection, there are two points that are utilized such as the pivot point and the tip point. The pivot point is the point where the first deflection occurs from the right. The tip point is the end/left top part of the specimen. More details about these points can be seen in Fig. 5 where the deflection angle is marked as \(\:\alpha\:\) . Figure 5 shows a sample of how the software used is provided in the picture which shows that the deflection angle is recorded as 53.26 o . 2.3.2. Deflection Radius To evaluate the curvature performance of the soft robotic finger, the deflection radius was recorded at the final stage. The deflection curve is the part of the specimen that forms a curve shape at t = 5 minutes. The curve is considered between the pivot point through the end of the curve shape. Furthermore, the radius of the curve is the distance between the origin of the curve to the curve itself. There are two steps involved in measuring the radius \(\:r\) of deflection curve (Fig. 6 ). The first step is to measure the radius of curve in pixel unit using image analysis software. As shown in the example, the curve radius is initially measured as 228 pixels. This pixel value is then converted into millimeters based on the calibration factor, where 1 pixel is equivalent to 0.26 mm. Applying this conversion, the resulting deflection radius is 60.32 mm. 2.4. ANOVA In this study, an analysis of variance (ANOVA) was conducted to determine the impact of various factors on the activation process of the specimen as the validation of the experimental result. Two experimental factors, which are setup configuration and applied current, were selected as independent variables. The response variables were deflection angle measured in degrees and deflection radius measured in millimeters. The P-value was used to determine whether each factor had a significant effect. A factor was considered significant if the P-value was less than 0.05. In addition to the main effects of setup and current, the interaction effect between the two factors was also observed to see if their combination significantly influenced the result. 3. Result 3.1. Deflection Angle Recording Each experiment was conducted for 5 minutes starting from t = 0 to t = 5 minutes, the photograph was taken in order to analyze the effect of the parameters on the deflections. Experiment 1 is conducted using setup 1 with 2 nitinol wires, 2 power supplies, and current applied 2A. Figure 7 through 7 f provides pictures of experiment 1 captured each minute. At the beginning of the experiment (t = 0), the specimen appeared nearly straight, forming an angle of 0° relative to the pivot line, as shown in Fig. 7 (a). This indicates that no deflection occurred prior to the activation. The images demonstrate an obvious bending behavior over time, corresponding to the continuous actuation and heating of the Nitinol wires. Figure 7 (b) illustrates that the specimen is deflected into 4.48°. At this time, the specimen is already heated for 1 minute. After 2 minutes of heating, the specimen deflected into 9.72° which is shown in Fig. 7 (c). Furthermore, after 3 minutes of heating, the specimen continued to deflect into 15.73° which is shown in Fig. 7 (d) and after 4 minutes of heating, the specimen deflected into 16.83° shown in Fig. 7 (e). Finally, at t = 5 minutes the finger reaches its final stage with deflection angle of 19.61° which is shown in Fig. 7 (f). This shows that the specimen deflection angle has gradually increased during the time due to the presence of heating actuation from the nitinol wires. In the following sections (4.2 to 4.4), only selected time points t = 1, 2, and 5 minutes are presented to focus on the key stages of deformation and to simplify comparison across setups. 3.2. Deflection Angle over Time In this section, the deflection angle was recorded starting from the initial state at t = 0 minutes to the final state at t = 5 minutes and the response grouped into three setup configurations (Setups 1–3). Simultaneously, the temperature of Nitinol wires was observed using thermocouples at multiple points depending on the setup. All experiments were conducted at constant room temperature to ensure thermal consistency and minimize the environmental influences. Figure 8 presents the plot of temperature and deflection angle for Setup 1 under three current variations of 2 A (Fig. 8 a), 4 A (Fig. 8 b), and 5.2 A (Fig. 8 c). In this configuration, two Nitinol wires were activated using two power supplies, resulting in two temperature measurement points, denoted as T1 and T2. In Fig. 8 a (Experiment 1, 2 A), both T1 and T2 exhibit a rapid temperature increase during the first minute of heating, reaching 70.5°C and 68.25°C, respectively. These values stabilized from t = 2 to t = 5 minutes, with relatively low standard deviations of 1.98°C for T1 and 1.58°C for T2 indicating a stable heating temperature after the initial phase. Simultaneously, the finger showed a nearly linear increase in deflection angle, reaching 19.61° by t = 5 minutes. This response aligns with the thermal activation behavior of the PLA as a shape memory material. This is due to the glass transition temperature of PLA which is at the range of 60°C to 65°C and which generates bending motion [ 38 ], [ 39 ]. For Experiment 2 with 4A current (Fig. 8 b), T1 and T2 increased rapidly to 125.5°C and 125.65°C, respectively, within the first minute. These values remained stable from t = 2 to t = 5 minutes, with standard deviations of 1.27°C for T1 and 0.92°C for T2. The deflection angle increased nearly linearly, reaching 35.20° at t = 5 minutes. Similarly, Fig. 8 c (Experiment 3, 5.2 A) illustrates a further increase in temperatures, with T1 and T2 reaching 138.5°C and 132.5°C, and stable with standard deviations of 1.70°C and 1.49°C, respectively. The deflection angle in this case reached 38.08°. The finger activation process of setup 2 was depicted in Fig. 9 , three Nitinol wires were activated using three power supplies, with temperature monitored at three points (T1, T2, and T3). The applied current levels were 2 A, 4 A, and 5.2 A, corresponding to Experiments 4, 5, and 6, respectively. Across all cases, the temperature sharply increased during the first minute of heating and quickly stabilized above 120°C from t = 2 to t = 5 minutes, demonstrating consistent and uniform thermal behavior across the actuator which is identical to temperature trends of the setup 1. At 2A (Fig. 9 a), the actuator reached a final deflection of 26.07°; at 4A (Fig. 9 b), the angle increased significantly to 41.57°; and at 5.2A (Fig. 9 c), it reached 42.87°. The nearly linear increase in deflection from t = 1 to t = 5 minutes in all three cases suggests reliable and sustained actuation under continuous heating. Compared to Setup 1, Setup 2 produced noticeably greater deflection at the same current levels, attributed to the increased number of active wires and power supplies. Figure 10 illustrates the deflection and temperature changes for Setup 3, which incorporates three Nitinol wires connected to a single power supply. Experiments were conducted at two current levels which are 4 A (Fig. 10 a) and 5.2 A (Fig. 10 b). Unlike Setups 1 and 2, the temperature behavior in Setup 3 is less stable and exhibits a different trend, with temperatures peaking at t = 1 minute and then gradually decreasing over time. At 4 A, the maximum temperatures at T1, T2, and T3 reached approximately 67.2°C, but dropped noticeably by t = 2 and t = 5 minutes, indicating insufficient thermal maintenance due to limited power distribution across the wires. Since the temperature drops below the glass transition temperature, the ability of the stimulus to deform the finger is also degraded. This unstable thermal behavior resulted in a relatively low deflection angle of 20.42°. At 5.2 A, although temperature stability slightly improved, the system still showed signs of thermal decay, and the final deflection angle increased to 31.47°. The trend observed here revealed that while the number of wires influences actuation capability, the availability of sufficient and distributed power is also critical. The reduced performance of Setup 3 compared to Setup 2, despite using the same number of Nitinol wires the number of power supplies also plays a crucial role on the heating performance. 3.3. Final Deflection Radius The deflection radius (r) represents the bending curvature of the finger at its final deformation state, measured at t = 5 minutes. Figure 11 (a-c) shows the final deformation geometry for Setup 1 (Experiments 1–3, respectively), including the calculated deflection angles and corresponding radii. The first setup indicates an inverse relationship between the deflection angle and the bending radius where smaller angles correspond to tighter bends. The ability of the finger to bend can determine the capability of the finger gripper to hold specimen in certain range of dimensions. Figure 12 displays the final curvature results for Setup 2, which was configured with three Nitinol wires and three power supplies. At 2A (Experiment 4), the finger reached a deflection angle of 27° with a radius of 61.8 mm. At 4A (Experiment 5), the angle increased to 40.15° with a radius of 54.9 mm, and at 5.2A (Experiment 6), the finger achieved its maximum angle of 42.2°, with a notably reduced radius of 37.21 mm. When comparing Setup 1 and Setup 2, it is evident that the same current can result in different bending and grasping capabilities depending on the setup configuration. The bending deformation in each finger also shows variations in the fin tightness. The bending in Setup 2 is more evenly distributed, leading to a more uniform curve, while Setup 1 displays sharper bending angles along the finger. Figure 13 illustrates the final deflection behavior under Setup 3, which uses three Nitinol wires powered by a single power supply. At 4A (Experiment 7), the deflection angle was 24.68° with a large radius of 116.17 mm, indicating only mild bending. At 5.2A (Experiment 8), the angle increased to 29.13°, and the radius decreased to 69.32 mm. From the figure, it is clear that the bending behavior differs between the two specimens. At 4A, the specimen exhibited the largest bending radius among all experiments, but it also had one of the lowest deflection angles for the 4A current specimens. When compared to the specimen with the lowest deflection angle (Setup 1, 2 A), the deflection radius is nearly doubled. This difference can be attributed to the lower heating capability, which results in reduced bending capability. For the 5.2A (Fig. 13 b) specimen, the deflection angle remains small, and when compared to Experiment 1, the deflection radius is similar. However, this specimen also displays a sharp bending concentrated at a point and uneven fin tightness after bending. Among all three setups, Setup 2 demonstrates better heat distribution due to the presence of more Nitinol wires and additional power supplies, which results in more uniform actuation. A limited number of power supplies can lead to uneven heat distribution and sudden temperature drops, which is undesirable for this application. Experiments 5 and 6 (Setup 2 with 4 A and 5.2 A) exhibit the best fin tightness, as there are no sudden sharp bends. This consistency promotes better grip and could possibly extend the lifespan of the device by minimizing the risk of fracture during use, while still providing strong bending and gripping capabilities. The deflection angle and radius results are summarized in Table 4 , which are then further analyzed using ANOVA. Table 4 Table of experiments Exp. Setup Current Fin Def. Angle (degree) Def. Radius (mm) 1 1 2 Downward 19.61 64.48 2 1 4 35.20 55.92 3 1 5.2 38.08 44.95 4 2 2 27.00 61.8 5 2 4 40.15 54.9 6 2 5.2 42.20 37.21 7 3 4 24.68 116.17 8 3 5.2 29.13 69.32 9 2 5.2 Upward 32.74 51.09 10 2 5.2 No fin 59.78 108.36 3.4. The Effect of Fin to the Deflection Figure 14 depicts the temperature and deflection angle responses for Setup 2 under three fin orientation configurations (a) fin facing downward, (b) fin facing upward, and (c) no fin. In all three cases, setup 2 with the best bending behavior was applied with three nitinol wires, three power supplies, and a constant current of 5.2 A. Temperature measurements (T1, T2, T3) show a uniform trend across all fin configurations, with rapid heating during the first minute and stabilization above 120°C from t = 2 to t = 5 minutes, confirming that the thermal input remained effectively constant through the process. Although the setup and the thermal activation remained consistent across all tests, the deflection angles varied noticeably depending on the orientation of the fin. This indicates that the fin plays an important role in the actuator's performance. When the fin was positioned downward, in the same direction as the bending motion (Fig. 14 a), the actuator achieved the highest deflection angle of 42.7°, showing the most effective response. When the fin was facing upward (Fig. 14 b), the deflection decreased slightly to 39.7°, which may be due to resistance opposing the natural movement. In the case with no fin (Fig. 14 c), the deflection was the lowest at 32.2°, suggesting a lack of support and directional control. These findings highlight the importance of fin orientation, where aligning the fin with the bending direction can significantly enhance the flexibility and overall actuation performance of the soft robotic finger. Figure 15 also illustrates the deflection radius for the three fin variations. The specimen with the downward-facing fin displayed a consistent and well-distributed bending, indicating a more uniform distribution of actuation forces. In contrast, the specimen without fin exhibited noticeably lower bending capability compared to the other two configurations. This result demonstrates that the presence of a fin significantly enhances the actuator’s bending performance, with the downward-facing fin, which is oriented in the same direction as the bending motion, providing the most effective deformation for finger gripper applications. These findings are consistent with our previous study [ 37 ], which emphasized the importance of fin in optimizing the bending behavior of 4D printing gripper fingers. 3.5. ANOVA Results In this study, ANOVA was conducted to evaluate the influence of experimental variables on the finger gripper deflection performance. The factors and corresponding response variables used in the analysis are listed on Table 4 . For the deflection angle, the ANOVA results presented in Table 5 show that both the setup configuration and the applied current have a statistically significant effect, indicating that each factor plays a meaningful role in influencing the bending behavior. The setup factor, which refers to the experimental configuration, demonstrated an F-value of 84.67 and a P-value of 0.002 below the significance threshold (α = 0.05), indicating its strong impact on the deflection. Similarly, the current factor had an F-value of 121.08 and a P-value of 0.001, which further highlights its significant role in the deflection behavior. The low P-values for both factors confirm that these variables meaningfully contribute to the variation in deflection angle. On the other hand, the effects of setup and current on the deflection radius were also investigated and presented in Table 6 . The setup factor has an F-value of 10.95 with a p-value of 0.042. This indicates that different setup configurations result in significant variations in the deflection radius. Conversely, the current factor has a lower F-value of 5.12 and a p-value of 0.108, suggesting that the current variations do not significantly affect the deflection radius within the tested range. Table 5 Analysis of Variance for Deflection Angle Source DF Adj SS Adj MS F-Value P-Value Setup 2 237.24 118.618 84.67 0.002 Current 2 339.25 169.624 121.08 0.001 Error 3 4.20 1.401 Total 9 458.000 Table 6 Analysis of Variance for Deflection Radius Source DF Adj SS Adj MS F-Value P-Value Setup 2 2662.1 1331.1 10.95 0.042 Current 2 1246.1 623.1 5.12 0.108 Error 3 364.48 121.6 Total 9 3977.2 To validate the assumptions underlying the ANOVA, residual plots for both deflection angle (Fig. 16 ) and deflection radius (Fig. 17 ) were analyzed. For both responses, the normal probability plot of residuals shows that most data points lie close to the reference line, indicating that the residuals are approximately normally distributed. The histogram of residuals supports this interpretation, showing a roughly symmetric distribution centered around zero. Furthermore, the residuals versus fitted values plot displays a random scatter without any obvious patterns, suggesting that the assumption of homoscedasticity (constant variance of residuals) is satisfied. The residual versus observation order plot also shows no discernible trend, indicating that the observations are independent and free from autocorrelation. Overall, the statistical analysis confirms that both Setup and Current significantly affect the deflection angle and deflection radius. The main effects analysis on Fig. 18 a and 18 b reveals that both the setup configuration and the applied current significantly influence the deflection angle and deflection radius of the gripper finger. For the deflection angle, Setup 2 resulted in the highest average value, indicating superior bending performance compared to Setups 1 and 3. This suggests that the configuration of Setup 2 may provide better heat distribution or wire alignment, leading to more effective actuation. In terms of current, a clear increasing trend was observed where higher currents produced greater deflection angles, with the maximum observed at 5.2 A. This confirms that increased electrical input enhances the activation of the Nitinol wires, thereby improving bending performance. For the deflection radius, a contrast pattern exists. Setup 3 produced the largest average radius, suggesting a wider and less effective curvature, while Setups 1 and 2 achieved tighter bends, which are more desirable for gripping applications. The effect of current on the radius was nonlinear since the radius increased at 4.0 A but sharply decreased at 5.2 A. This reduction in radius at higher current levels indicates a tighter curvature, aligning with the increased deflection angle observed. The interaction plots further on Fig. 19 further support the significant influence of both setup configuration and current level on the deflection behavior. For deflection angle, Setup 2 exhibited the most responsive behavior to increasing current, achieving the highest deflection across all current levels. This indicates that Setup 2 not only performs better in isolation but also amplifies the effect of higher current more effectively than other setups. In contrast, Setup 3 consistently yielded lower deflection angles, showing limited responsiveness to current changes. For deflection radius, the interaction effect is equally notable. Setup 2 displayed a steady decrease in radius with increasing current, suggesting a progressive improvement in bend tightness as an essential characteristic for gripping applications. While Setup 1 followed a similar trend with smaller magnitude, Setup 3 demonstrated an unusual pattern which started with a significantly wider bend and only achieved a tighter radius at the highest current level. Overall, Setup 2, which uses 3 nitinol wires, 3 power supplies with 5.2 A current (Experiment 6) produced both a large deflection angle and a relatively small deflection radius. This combination suggests that Setup 2 offers a strong and tight bending motion, making it more effective for gripping tasks. 4. Conclusion The self-actuating finger gripper system design has successfully applied into the finger and activated the gripper through heat stimulus induced by the nitinol wires. This study concludes that both the experimental setup and applied current significantly affect the deflection behavior of the soft robotic finger. Among the three configurations, Setup 2 using three Nitinol wires and three power supplies consistently achieved the highest deflection angles and tightest bending radius, especially at 5.2 A, making it the most effective for gripping applications. In contrast, Setup 3 showed lower performance due to uneven heat distribution from a single power supply. ANOVA results confirmed that setup and current significantly influenced deflection angle, while only setup significantly affected the radius. Additionally, the fin orientation also proved to be a key factor, with the downward-facing fin leading to better and more consistent bending. Declarations Acknowledgments We would like to express our gratitude to the Institution of Mechanical Engineers (IMechE) for this project’s financial support through the research grant of IMechE SEAR Mini Research Grant 2024-2025. All the facilities and support in this project were also provided by the Center for Research and Community Services at Sampoerna University Indonesia. Data Availability My manuscript has no associated data in a data repository. Competing Interest Funding: the corresponding author received research grant from Institution of Mechanical Engineers (IMechE) SEAR Mini Research Grant 2024-2025. Other authors have no relevant financial or non-financial interests to disclose. Author Contributions Kushendarsyah Saptaji : Conceptualization, Methodology, Supervision. Azhari Tumada : Literature review, Experiment, Writing-original draft preparation. Octarina Adiati Juniasih : Writing-original draft preparation. Azmir Azhari : Writing- Reviewing and Editing. 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Lu et al. , “4D‐Printing of Photoswitchable Actuators,” Angewandte Chemie International Edition , vol. 60, no. 10, pp. 5536–5543, Mar. 2021. C. De Marco et al. , “Indirect 3D and 4D Printing of Soft Robotic Microstructures,” Advanced Materials Technologies , vol. 4, no. 9, p. 1900332, Sep. 2019. D. Schaefer and W. M. Cheung, “Smart Packaging: Opportunities and Challenges,” Procedia CIRP , vol. 72, pp. 1022–1027, 2018. Z. Wang, K. Or, and S. Hirai, “A dual-mode soft gripper for food packaging,” Robotics and Autonomous Systems , vol. 125, p. 103427, Mar. 2020. K. Saptaji, R. A. Wijaya, and O. A. Juniasih, “Optimizing 4D-printed grippers: the role of finger design and thermal stimulus,” Progress in Additive Manufacturing , Jan. 2025. F. I. Maina, N. Osinde, J. K. Odira, P. K. Wanjiru, and M. W. Mwangi, “4D Printing and Characterization of Shape Memory Polymer (SMP) Based Smart Gripper,” European Journal of Engineering Research and Science , vol. 5, no. 10, pp. 1204–1211, Oct. 2020. L. P. Muthe, K. Pickering, and C. Gauss, “A Review of 3D/4D Printing of Poly-Lactic Acid Composites with Bio-Derived Reinforcements,” Composites Part C: Open Access , vol. 8, no. April, p. 100271, 2022. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7060696","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":483719831,"identity":"4826c4d4-36f9-4f11-bff7-a8de195f7230","order_by":0,"name":"Kushendarsyah 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for two nitinol wires as heat actuator with two power supplies\u003c/p\u003e","description":"","filename":"2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7060696/v1/851030fa7bb86c923feaf01c.jpg"},{"id":86696326,"identity":"bec05bb9-7f0e-4a7c-a7d9-409f00f5c314","added_by":"auto","created_at":"2025-07-14 15:26:10","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":101389,"visible":true,"origin":"","legend":"\u003cp\u003eSetup 2 for three nitinol wires as heat actuator with three power supplies\u003c/p\u003e","description":"","filename":"3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7060696/v1/6f48cb645c4a74de809e0dd1.jpg"},{"id":86696322,"identity":"179625bf-fde0-4fee-ab95-041e14d627a4","added_by":"auto","created_at":"2025-07-14 15:26:10","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":108733,"visible":true,"origin":"","legend":"\u003cp\u003eSetup 3 for three nitinol wire as heat actuator with one power supply\u003c/p\u003e","description":"","filename":"4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7060696/v1/ebfedc3d185d186cb83a8d80.jpg"},{"id":86695059,"identity":"fe4cf848-da80-41b0-a34e-334cc48df9a9","added_by":"auto","created_at":"2025-07-14 15:18:10","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":57918,"visible":true,"origin":"","legend":"\u003cp\u003eIllustration of deflection angle measurements\u003c/p\u003e","description":"","filename":"5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7060696/v1/6b9d3179d9a36a0f16c89452.jpg"},{"id":86696324,"identity":"d5663df8-4d32-4c5b-8209-f82e5f7b0e0e","added_by":"auto","created_at":"2025-07-14 15:26:10","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":59686,"visible":true,"origin":"","legend":"\u003cp\u003eIllustration of deflection radius measurements\u003c/p\u003e","description":"","filename":"6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7060696/v1/5e5e36a50e224d3b1f6cbecb.jpg"},{"id":86695065,"identity":"a988b8d5-1b3a-47b5-921a-ef2ed731c8ee","added_by":"auto","created_at":"2025-07-14 15:18:10","extension":"jpg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":112158,"visible":true,"origin":"","legend":"\u003cp\u003ePhotos taken for Experiment 1 from (a) t=0 m, (b) t=1 m, (c) t=2 m, (d) t=3 m, (e) t=4 m, and (f) t=5 m. The sequence shows the deformation of gripper finger due to the heat induced by nitinol wires.\u003c/p\u003e","description":"","filename":"7.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7060696/v1/b09a27559396af1a2c1c54bb.jpg"},{"id":86696842,"identity":"e61c96a4-e33d-4859-bb04-a7d3a7ba8a80","added_by":"auto","created_at":"2025-07-14 15:34:10","extension":"jpg","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":104205,"visible":true,"origin":"","legend":"\u003cp\u003eDeflection angle and temperature profiles for Setup 1 with two Nitinol wires and two power supplies at (a) 2 A, (b) 4 A, and (c) 5.2 A\u003c/p\u003e","description":"","filename":"8.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7060696/v1/04ada0603c3eab988956058b.jpg"},{"id":86696844,"identity":"003a6584-499e-46f3-9889-0b51f1a4fe7d","added_by":"auto","created_at":"2025-07-14 15:34:10","extension":"jpg","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":80871,"visible":true,"origin":"","legend":"\u003cp\u003eDeflection and temperature results for Setup 2 using three wires and three power supplies at (a) 2 A, (b) 4 A, and (c) 5.2 A.\u003c/p\u003e","description":"","filename":"9.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7060696/v1/363d84fc22c0f913f6de57bf.jpg"},{"id":86695075,"identity":"252b6c37-5ff3-4ef9-844d-6cf3f663539f","added_by":"auto","created_at":"2025-07-14 15:18:10","extension":"jpg","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":55423,"visible":true,"origin":"","legend":"\u003cp\u003eDeflection and temperature trends for Setup 3 using three nitinol wires with one power supply at (a) 4 A and (b) 5.2 A\u003c/p\u003e","description":"","filename":"10.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7060696/v1/c0addf16a4be5dd3a86b6235.jpg"},{"id":86696843,"identity":"4c3f8cea-92b9-4ae1-b2bc-a65359192a64","added_by":"auto","created_at":"2025-07-14 15:34:10","extension":"jpg","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":73690,"visible":true,"origin":"","legend":"\u003cp\u003eFinal deflection geometry of the soft robotic finger under Setup 1, showing calculated deflection angles (θ) and corresponding radii of curvature (r) for (left to right): Experiment 1 (2 A), Experiment 2 (4 A), and Experiment 3 (5.2 A).\u003c/p\u003e","description":"","filename":"11.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7060696/v1/3f9db558375681dfa6cc21aa.jpg"},{"id":86695072,"identity":"bc7d631c-c85c-46fc-84e6-a50127457ee5","added_by":"auto","created_at":"2025-07-14 15:18:10","extension":"jpg","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":73134,"visible":true,"origin":"","legend":"\u003cp\u003eFinal deflection geometry of the soft robotic finger under Setup 2, with three Nitinol wires and three power supplies. Deflection angles (θ) and radii of curvature (r) are shown for (left to right): Experiment 4 (2 A), Experiment 5 (4 A), and Experiment 6 (5.2 A).\u003c/p\u003e","description":"","filename":"12.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7060696/v1/9bf0f92c92bb5e960eac6bde.jpg"},{"id":86695077,"identity":"b174e282-c847-49cd-832a-820fcc3fa7cc","added_by":"auto","created_at":"2025-07-14 15:18:10","extension":"jpg","order_by":13,"title":"Figure 13","display":"","copyAsset":false,"role":"figure","size":56160,"visible":true,"origin":"","legend":"\u003cp\u003eFinal deflection geometry of the soft robotic finger under Setup 3, using three Nitinol wires powered by a single power supply. 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Setup remained consistent across all cases, while deflection angles varied based on fin configuration.\u003c/p\u003e","description":"","filename":"15.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7060696/v1/ddfea9f28b8c5bb5e00de284.jpg"},{"id":86695080,"identity":"1aa5df06-b835-441e-93a7-1901f9380de9","added_by":"auto","created_at":"2025-07-14 15:18:10","extension":"jpg","order_by":16,"title":"Figure 16","display":"","copyAsset":false,"role":"figure","size":62371,"visible":true,"origin":"","legend":"\u003cp\u003eResidual Plots for Deflection Angle\u003c/p\u003e","description":"","filename":"16.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7060696/v1/731b6bf497632e0758e34e5a.jpg"},{"id":86696845,"identity":"d70884e0-8cf3-4fe3-9e9a-dffe97c6eb9a","added_by":"auto","created_at":"2025-07-14 15:34:10","extension":"jpg","order_by":17,"title":"Figure 17","display":"","copyAsset":false,"role":"figure","size":59428,"visible":true,"origin":"","legend":"\u003cp\u003eResidual Plots for Deflection Radius\u003c/p\u003e","description":"","filename":"17.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7060696/v1/ee9878223d699b42b011995e.jpg"},{"id":86696335,"identity":"3dff39bb-c176-46b1-a08b-ded5a3331c57","added_by":"auto","created_at":"2025-07-14 15:26:11","extension":"jpg","order_by":18,"title":"Figure 18","display":"","copyAsset":false,"role":"figure","size":49896,"visible":true,"origin":"","legend":"\u003cp\u003eMain effect of the setup and current to the deflection angle (left) and deflection radius (right)\u003c/p\u003e","description":"","filename":"18.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7060696/v1/ac4adcf922985e92f7097a82.jpg"},{"id":86695115,"identity":"3623adbe-ffdb-4157-92f4-adddab7393b0","added_by":"auto","created_at":"2025-07-14 15:18:11","extension":"jpg","order_by":19,"title":"Figure 19","display":"","copyAsset":false,"role":"figure","size":43376,"visible":true,"origin":"","legend":"\u003cp\u003eInteraction plot of the setup and current to the deflection angle (left) and deflection radius (right)\u003c/p\u003e","description":"","filename":"19.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7060696/v1/54ee32a48d41e1ec94febb59.jpg"},{"id":90536945,"identity":"c0990315-1e84-41f1-bf45-e528b70e7cca","added_by":"auto","created_at":"2025-09-03 20:39:55","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2246414,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7060696/v1/7d176f4f-dfbe-4395-b71e-36deae3775ba.pdf"}],"financialInterests":"","formattedTitle":"Assessing Heat-Driven 4D Printed Finger Actuators with Conductive Wires: A Parametric Analysis","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eFour-dimensional (4D) printing has emerged as a transformative extension of three-dimensional (3D) printing, enabling the fabrication of dynamic shape shifting structures [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. In general, 3D printing is an additive manufacturing (AM) technique in which materials are deposited layer by layer to create three-dimensional objects such as eyeglasses, custom prosthetic devices, and dental implants [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e], [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. This 3D printing method enables the fabrication of personalized models from volumetric digital design used for preoperative planning and constructing personalized prostheses for patients [\u003cspan additionalcitationids=\"CR5\" citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]\u0026ndash;[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. It offers the advantage of producing personalized and less post-processing compared to the conventional manufacturing.\u003c/p\u003e\u003cp\u003eThe same methods used in 3D printing are applied in 4D printing, often referred to shape-morphing systems [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e], [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. With the integration of the fourth dimension, 4D printing further advances these capabilities by allowing printed structures to morph and adapt over time according to pre-programmed mechanisms [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. The fourth dimension of 4D printing, on the other hand, is the time-dependent shape change that occurs after the printing, allowing the 3D shape that is produced to transform into new shapes in reaction to external stimuli such as heat, light, humidity, water, voltage, and pH [\u003cspan additionalcitationids=\"CR11\" citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]\u0026ndash;[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Thus, shape memory materials employed in 4D printing are considered programmable [\u003cspan additionalcitationids=\"CR14\" citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]\u0026ndash;[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThe applications of 4D print have gathered into various fields, such as medical, aerospace, and soft robotics. In the field of robotics, 4D-printed actuators have attracted significant research interest due to their programmable movement [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e], [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. An actuator plays a critical role in robotics by mimicking the motor-response mechanism that enables motion in response to specific commands [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e], [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. However, conventional actuators, typically made from rigid material which face limitations in flexibility and adaptability. Their inability to handle complex shapes or dynamic environments limits their application in specific applications [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. This limitation has driven the development of soft robotics, which seeks to address these challenges by employing materials such as elastomers and polymers that can deform significantly and return to their original shape [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eSoft actuators, as a core element of soft robotics, have shown promise in applications such as prosthetics, medical devices, and automation systems [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e], [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Compared to rigid actuators, soft actuators offer enhanced range of motion, safer interaction with delicate objects, lightweight design, and higher power-to-weight ratio [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. Moreover, Kim et. al. (2019) mentioned soft actuators can withstand large strains without permanent damage, which contributes to greater durability and functional lifespan [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. The soft actuators work by converting input stimuli into mechanical motion. They are classified based on the type of stimulus required such as electroactive polymers rely on chemical signals, pneumatic [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e] and hydraulic actuators use air or liquids, shape memory materials respond to heat, while others react to light, magnetic fields, or electric fields [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. These actuators must meet demands for precision, speed, reversibility, and the ability to bend, extend, or twist, while delivering sufficient force.\u003c/p\u003e\u003cp\u003eThe choice of actuation mechanism significantly influences the size, weight, power requirements, sensing systems, and control systems of soft robotic devices [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. Hence, actuator systems selection must be aligned with the targeted functionality and application needs. With 4D printing, which enables objects to morph over time in response to stimuli, the design challenge increases. The applications of actuations must account for material properties, geometrical effect, and external triggers to ensure reliable performance [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e], [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. One of the most common examples in the applications of 4D printing in soft robotics is in gripping mechanism. Grippers are essential components in various industries, particularly in automation and robotics, where they are used for handling, assembling, and manipulating objects [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e], [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. Conventional grippers often require complex mechanisms to adjust grips, which may reduce efficiency and increase failure rates. 4D-printed grippers overcome this by integrating smart materials capable of self-actuation. When stimulated (e.g., by heat), these materials deform in a pre-programmed manner, allowing the gripper to autonomously adapt to various object geometries [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e], [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eBeyond traditional automation, the concept of 4D-printed soft grippers can also be extended to smart packaging systems [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]. Smart packaging increasingly demands adaptive handling, secure sealing, and controlled release of products, all of which could benefit from soft gripper-inspired mechanisms. By integrating 4D-printed, heat-responsive soft grippers into packaging, it becomes possible to achieve automatic opening, closing, or repositioning functions in response to temperature changes. This approach combines the programmability and flexibility of soft grippers with the needs of modern packaging, enhancing product safety, reducing waste, and supporting sustainability efforts through more intelligent, responsive packaging designs [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]. The self-actuating gripper finger developed in this study has potential applications in smart manufacturing, medical devices, logistics, and operations in special environments. Its ability to respond to external stimuli without complex mechanical systems supports the development of flexible, efficient, and adaptive technologies. These characteristics align with Sustainable Development Goal (SDG) 9, which promotes innovation and the creation of resilient infrastructure for sustainable industrial advancement.\u003c/p\u003e\u003cp\u003eTherefore, this research aims to bridge the gap in 4D printing by exploring the combined use of shape memory polymers (SMP), specific finger design and heat-conducting wire to create a self-actuating gripper finger. While SMPs have been studied extensively, their application in self-actuating grippers, especially when stimulated by heat-conducting wire, remains underexplored. According to problem stated, the objectives of this study are to observe the effect of current, temperature, and wire arrangement to the deflection of 4D self-actuator finger, to obtain the optimum parameters such as current, temperature, and wire arrangement as the input of heat stimulus to the 4D self-actuator finger based on the deflection angle and radius of the deflection curve. In addition, the effect of fin to the deflection of the 4D self-actuator finger is also explored. Furthermore, this paper will cover the methodology, result and discussion, and conclusion.\u003c/p\u003e"},{"header":"2. Methodology","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003e2.1. Materials and Design\u003c/h2\u003e\u003cp\u003eIn this experiment, the self-actuator finger was designed in order to represent one finger of the whole gripper. The self-actuator finger was fabricated using Fused Deposition Modeling (FDM) 3D Printer (Anycubic i3 Mega) with parameters shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Polylactic acid (PLA) as the shape memory polymer (SMP) was used for the main part of the finger. The nickel-titanium (nitinol) wire with 1 mm diameter incorporated into the system as the heat conductive wire, and copper wire of 1 mm diameter used to transfer electricity into the nitinol wire. The general design and dimensions of the self-actuator finger is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e adapted from [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e].\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003ePrinting Parameter\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"2\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eParameters\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eValue\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePrinting Speed\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e50 mm/s\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePrinting Pattern\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eLine\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePrinting thickness\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.2 mm\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePrinting Temperature\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e205\u003csup\u003eo\u003c/sup\u003eC\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBed Temperature\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e60\u003csup\u003eo\u003c/sup\u003eC\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eInfill Density\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e60%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\u003ch2\u003e2.2. Experimental Setup\u003c/h2\u003e\u003cp\u003eIn addition to the self-actuated soft robotic finger, the experimental setup consists of a digital power supply, a thermocouple for temperature measurement, and a laptop for data acquisition and control. The power supply used in this study is Digital Ways DW PS31505W with detailed specifications presented in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. In this study, a Nitinol wire, which is an alloy composed of nickel and titanium with shape memory properties, is integrated into the finger gripper to enable heat-induced actuation. Nitinol is widely recognized for its use in the space industry and has also been studied in the context of four-dimensional printing due to its ability to respond to thermal stimuli. A thermocouple is placed near the Nitinol wires to monitor the heating process in real time, while a laptop is used to record both temperature and deflection data during the experiments.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003ePower Supply Specification\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"2\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSpecification\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eValue\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOutput Voltage\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0\u0026ndash;15 V\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOutput Current\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0\u0026ndash;5 A\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOutput Current\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e300 W\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eThree experimental setups were proposed in this study to analyze two main parameters such as wire arrangement and current input. Each setup consists of a self-actuated specimen, a temperature sensor (thermocouple), Nitinol wires, copper wires, and a power supply system. The first setup uses two Nitinol wires; each connected to an individual power supply (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). The second setup is similar to the first but incorporates one additional Nitinol wire and power supply (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). The third setup also utilizes three Nitinol wires; however, it employs only a single power supply with a three-way current divider to distribute the current evenly among the wires (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). Thermocouples were attached to each Nitinol wire across all setups to monitor temperature changes during actuation. These three configurations were used in a total of ten experiments, varying in wire arrangement and current levels, as summarized in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e.\u003c/p\u003e\u003cp\u003eInitially, the end part of the finger actuator was clamped using a vice clamp. The Nitinol wires were then activated by applying electric current to generate heat, which was transferred to the finger actuator. This thermal input was expected to induce deflection in the actuator. The heating process was maintained for five minutes, during which the temperature was recorded at one-minute interval. Prior to the experiment, the temperature sensors were calibrated using room temperature and boiling water to ensure accurate readings. The effects of the experimental parameters were evaluated based on deflection angle and deflection radius. The deflection angle was measured every minute, while the deflection radius was measured at the fifth minute, when the actuator had reached its final bending position.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eExperiments List\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eExperiment\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eSetup Used\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003eWire Arrangement\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eCurrent (Ampere)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eFin\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNumber of Nitinol Wire\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eNumber of Power Supply\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\" morerows=\"7\" rowspan=\"8\"\u003e\u003cp\u003eFacing Downward\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e5.2\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e5.2\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e5.2\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e5.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eFacing Upward\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e5.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eNo Fin\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\u003ch2\u003e2.3. Method of Measurement\u003c/h2\u003e\u003cdiv id=\"Sec6\" class=\"Section3\"\u003e\u003ch2\u003e2.3.1. Deflection Angle\u003c/h2\u003e\u003cp\u003eTo measure the degree of deflection, there are two points that are utilized such as the pivot point and the tip point. The pivot point is the point where the first deflection occurs from the right. The tip point is the end/left top part of the specimen. More details about these points can be seen in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e where the deflection angle is marked as \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\alpha\\:\\)\u003c/span\u003e\u003c/span\u003e. Figure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e shows a sample of how the software used is provided in the picture which shows that the deflection angle is recorded as 53.26\u003csup\u003eo\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec7\" class=\"Section3\"\u003e\u003ch2\u003e2.3.2. Deflection Radius\u003c/h2\u003e\u003cp\u003eTo evaluate the curvature performance of the soft robotic finger, the deflection radius was recorded at the final stage. The deflection curve is the part of the specimen that forms a curve shape at t\u0026thinsp;=\u0026thinsp;5 minutes. The curve is considered between the pivot point through the end of the curve shape. Furthermore, the radius of the curve is the distance between the origin of the curve to the curve itself. There are two steps involved in measuring the radius \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:r\\)\u003c/span\u003e\u003c/span\u003e of deflection curve (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e). The first step is to measure the radius of curve in pixel unit using image analysis software. As shown in the example, the curve radius is initially measured as 228 pixels. This pixel value is then converted into millimeters based on the calibration factor, where 1 pixel is equivalent to 0.26 mm. Applying this conversion, the resulting deflection radius is 60.32 mm.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003e2.4. ANOVA\u003c/h2\u003e\u003cp\u003eIn this study, an analysis of variance (ANOVA) was conducted to determine the impact of various factors on the activation process of the specimen as the validation of the experimental result. Two experimental factors, which are setup configuration and applied current, were selected as independent variables. The response variables were deflection angle measured in degrees and deflection radius measured in millimeters. The P-value was used to determine whether each factor had a significant effect. A factor was considered significant if the P-value was less than 0.05. In addition to the main effects of setup and current, the interaction effect between the two factors was also observed to see if their combination significantly influenced the result.\u003c/p\u003e\u003c/div\u003e"},{"header":"3. Result","content":"\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e\u003ch2\u003e3.1. Deflection Angle Recording\u003c/h2\u003e\u003cp\u003eEach experiment was conducted for 5 minutes starting from t\u0026thinsp;=\u0026thinsp;0 to t\u0026thinsp;=\u0026thinsp;5 minutes, the photograph was taken in order to analyze the effect of the parameters on the deflections. Experiment 1 is conducted using setup 1 with 2 nitinol wires, 2 power supplies, and current applied 2A. Figure\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e through \u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ef provides pictures of experiment 1 captured each minute.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eAt the beginning of the experiment (t\u0026thinsp;=\u0026thinsp;0), the specimen appeared nearly straight, forming an angle of 0\u0026deg; relative to the pivot line, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e(a). This indicates that no deflection occurred prior to the activation. The images demonstrate an obvious bending behavior over time, corresponding to the continuous actuation and heating of the Nitinol wires. Figure\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e(b) illustrates that the specimen is deflected into 4.48\u0026deg;. At this time, the specimen is already heated for 1 minute. After 2 minutes of heating, the specimen deflected into 9.72\u0026deg; which is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e(c). Furthermore, after 3 minutes of heating, the specimen continued to deflect into 15.73\u0026deg; which is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e(d) and after 4 minutes of heating, the specimen deflected into 16.83\u0026deg; shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e(e).\u003c/p\u003e\u003cp\u003eFinally, at t\u0026thinsp;=\u0026thinsp;5 minutes the finger reaches its final stage with deflection angle of 19.61\u0026deg; which is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e(f). This shows that the specimen deflection angle has gradually increased during the time due to the presence of heating actuation from the nitinol wires. In the following sections (4.2 to 4.4), only selected time points t\u0026thinsp;=\u0026thinsp;1, 2, and 5 minutes are presented to focus on the key stages of deformation and to simplify comparison across setups.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003e3.2. Deflection Angle over Time\u003c/h2\u003e\u003cp\u003eIn this section, the deflection angle was recorded starting from the initial state at t\u0026thinsp;=\u0026thinsp;0 minutes to the final state at t\u0026thinsp;=\u0026thinsp;5 minutes and the response grouped into three setup configurations (Setups 1\u0026ndash;3). Simultaneously, the temperature of Nitinol wires was observed using thermocouples at multiple points depending on the setup. All experiments were conducted at constant room temperature to ensure thermal consistency and minimize the environmental influences.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e presents the plot of temperature and deflection angle for Setup 1 under three current variations of 2 A (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003ea), 4 A (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003eb), and 5.2 A (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003ec). In this configuration, two Nitinol wires were activated using two power supplies, resulting in two temperature measurement points, denoted as T1 and T2. In Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003ea (Experiment 1, 2 A), both T1 and T2 exhibit a rapid temperature increase during the first minute of heating, reaching 70.5\u0026deg;C and 68.25\u0026deg;C, respectively. These values stabilized from t\u0026thinsp;=\u0026thinsp;2 to t\u0026thinsp;=\u0026thinsp;5 minutes, with relatively low standard deviations of 1.98\u0026deg;C for T1 and 1.58\u0026deg;C for T2 indicating a stable heating temperature after the initial phase. Simultaneously, the finger showed a nearly linear increase in deflection angle, reaching 19.61\u0026deg; by t\u0026thinsp;=\u0026thinsp;5 minutes. This response aligns with the thermal activation behavior of the PLA as a shape memory material. This is due to the glass transition temperature of PLA which is at the range of 60\u0026deg;C to 65\u0026deg;C and which generates bending motion [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e], [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eFor Experiment 2 with 4A current (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003eb), T1 and T2 increased rapidly to 125.5\u0026deg;C and 125.65\u0026deg;C, respectively, within the first minute. These values remained stable from t\u0026thinsp;=\u0026thinsp;2 to t\u0026thinsp;=\u0026thinsp;5 minutes, with standard deviations of 1.27\u0026deg;C for T1 and 0.92\u0026deg;C for T2. The deflection angle increased nearly linearly, reaching 35.20\u0026deg; at t\u0026thinsp;=\u0026thinsp;5 minutes. Similarly, Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003ec (Experiment 3, 5.2 A) illustrates a further increase in temperatures, with T1 and T2 reaching 138.5\u0026deg;C and 132.5\u0026deg;C, and stable with standard deviations of 1.70\u0026deg;C and 1.49\u0026deg;C, respectively. The deflection angle in this case reached 38.08\u0026deg;.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eThe finger activation process of setup 2 was depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e, three Nitinol wires were activated using three power supplies, with temperature monitored at three points (T1, T2, and T3). The applied current levels were 2 A, 4 A, and 5.2 A, corresponding to Experiments 4, 5, and 6, respectively. Across all cases, the temperature sharply increased during the first minute of heating and quickly stabilized above 120\u0026deg;C from t\u0026thinsp;=\u0026thinsp;2 to t\u0026thinsp;=\u0026thinsp;5 minutes, demonstrating consistent and uniform thermal behavior across the actuator which is identical to temperature trends of the setup 1. At 2A (Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003ea), the actuator reached a final deflection of 26.07\u0026deg;; at 4A (Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003eb), the angle increased significantly to 41.57\u0026deg;; and at 5.2A (Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003ec), it reached 42.87\u0026deg;. The nearly linear increase in deflection from t\u0026thinsp;=\u0026thinsp;1 to t\u0026thinsp;=\u0026thinsp;5 minutes in all three cases suggests reliable and sustained actuation under continuous heating. Compared to Setup 1, Setup 2 produced noticeably greater deflection at the same current levels, attributed to the increased number of active wires and power supplies.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e illustrates the deflection and temperature changes for Setup 3, which incorporates three Nitinol wires connected to a single power supply. Experiments were conducted at two current levels which are 4 A (Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003ea) and 5.2 A (Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003eb). Unlike Setups 1 and 2, the temperature behavior in Setup 3 is less stable and exhibits a different trend, with temperatures peaking at t\u0026thinsp;=\u0026thinsp;1 minute and then gradually decreasing over time. At 4 A, the maximum temperatures at T1, T2, and T3 reached approximately 67.2\u0026deg;C, but dropped noticeably by t\u0026thinsp;=\u0026thinsp;2 and t\u0026thinsp;=\u0026thinsp;5 minutes, indicating insufficient thermal maintenance due to limited power distribution across the wires. Since the temperature drops below the glass transition temperature, the ability of the stimulus to deform the finger is also degraded. This unstable thermal behavior resulted in a relatively low deflection angle of 20.42\u0026deg;. At 5.2 A, although temperature stability slightly improved, the system still showed signs of thermal decay, and the final deflection angle increased to 31.47\u0026deg;. The trend observed here revealed that while the number of wires influences actuation capability, the availability of sufficient and distributed power is also critical. The reduced performance of Setup 3 compared to Setup 2, despite using the same number of Nitinol wires the number of power supplies also plays a crucial role on the heating performance.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003e3.3. Final Deflection Radius\u003c/h2\u003e\u003cp\u003eThe deflection radius (r) represents the bending curvature of the finger at its final deformation state, measured at t\u0026thinsp;=\u0026thinsp;5 minutes. Figure\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003e (a-c) shows the final deformation geometry for Setup 1 (Experiments 1\u0026ndash;3, respectively), including the calculated deflection angles and corresponding radii. The first setup indicates an inverse relationship between the deflection angle and the bending radius where smaller angles correspond to tighter bends. The ability of the finger to bend can determine the capability of the finger gripper to hold specimen in certain range of dimensions.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig12\" class=\"InternalRef\"\u003e12\u003c/span\u003e displays the final curvature results for Setup 2, which was configured with three Nitinol wires and three power supplies. At 2A (Experiment 4), the finger reached a deflection angle of 27\u0026deg; with a radius of 61.8 mm. At 4A (Experiment 5), the angle increased to 40.15\u0026deg; with a radius of 54.9 mm, and at 5.2A (Experiment 6), the finger achieved its maximum angle of 42.2\u0026deg;, with a notably reduced radius of 37.21 mm. When comparing Setup 1 and Setup 2, it is evident that the same current can result in different bending and grasping capabilities depending on the setup configuration. The bending deformation in each finger also shows variations in the fin tightness. The bending in Setup 2 is more evenly distributed, leading to a more uniform curve, while Setup 1 displays sharper bending angles along the finger.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig13\" class=\"InternalRef\"\u003e13\u003c/span\u003e illustrates the final deflection behavior under Setup 3, which uses three Nitinol wires powered by a single power supply. At 4A (Experiment 7), the deflection angle was 24.68\u0026deg; with a large radius of 116.17 mm, indicating only mild bending. At 5.2A (Experiment 8), the angle increased to 29.13\u0026deg;, and the radius decreased to 69.32 mm. From the figure, it is clear that the bending behavior differs between the two specimens. At 4A, the specimen exhibited the largest bending radius among all experiments, but it also had one of the lowest deflection angles for the 4A current specimens. When compared to the specimen with the lowest deflection angle (Setup 1, 2 A), the deflection radius is nearly doubled. This difference can be attributed to the lower heating capability, which results in reduced bending capability. For the 5.2A (Fig.\u0026nbsp;\u003cspan refid=\"Fig13\" class=\"InternalRef\"\u003e13\u003c/span\u003eb) specimen, the deflection angle remains small, and when compared to Experiment 1, the deflection radius is similar. However, this specimen also displays a sharp bending concentrated at a point and uneven fin tightness after bending.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eAmong all three setups, Setup 2 demonstrates better heat distribution due to the presence of more Nitinol wires and additional power supplies, which results in more uniform actuation. A limited number of power supplies can lead to uneven heat distribution and sudden temperature drops, which is undesirable for this application. Experiments 5 and 6 (Setup 2 with 4 A and 5.2 A) exhibit the best fin tightness, as there are no sudden sharp bends. This consistency promotes better grip and could possibly extend the lifespan of the device by minimizing the risk of fracture during use, while still providing strong bending and gripping capabilities. The deflection angle and radius results are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, which are then further analyzed using ANOVA.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eTable of experiments\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"9\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eExp.\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e\u003cp\u003eSetup\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eCurrent\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eFin\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e\u003cp\u003eDef. Angle (degree)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003eDef. Radius (mm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"1\" nameend=\"c9\" namest=\"c9\"\u003e\u0026nbsp;\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" morerows=\"7\" nameend=\"c6\" namest=\"c5\" rowspan=\"8\"\u003e\u003cp\u003eDownward\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e19.61\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e\u003cp\u003e64.48\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e35.20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e\u003cp\u003e55.92\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e5.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e38.08\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e\u003cp\u003e44.95\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e27.00\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e\u003cp\u003e61.8\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e40.15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e\u003cp\u003e54.9\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e5.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e42.20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e\u003cp\u003e37.21\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e24.68\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e\u003cp\u003e116.17\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e5.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e29.13\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e\u003cp\u003e69.32\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e5.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e\u003cp\u003eUpward\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e32.74\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e\u003cp\u003e51.09\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e5.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e\u003cp\u003eNo fin\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e59.78\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e\u003cp\u003e108.36\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\u003ch2\u003e3.4. The Effect of Fin to the Deflection\u003c/h2\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig14\" class=\"InternalRef\"\u003e14\u003c/span\u003e depicts the temperature and deflection angle responses for Setup 2 under three fin orientation configurations (a) fin facing downward, (b) fin facing upward, and (c) no fin. In all three cases, setup 2 with the best bending behavior was applied with three nitinol wires, three power supplies, and a constant current of 5.2 A. Temperature measurements (T1, T2, T3) show a uniform trend across all fin configurations, with rapid heating during the first minute and stabilization above 120\u0026deg;C from t\u0026thinsp;=\u0026thinsp;2 to t\u0026thinsp;=\u0026thinsp;5 minutes, confirming that the thermal input remained effectively constant through the process.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eAlthough the setup and the thermal activation remained consistent across all tests, the deflection angles varied noticeably depending on the orientation of the fin. This indicates that the fin plays an important role in the actuator's performance. When the fin was positioned downward, in the same direction as the bending motion (Fig.\u0026nbsp;\u003cspan refid=\"Fig14\" class=\"InternalRef\"\u003e14\u003c/span\u003ea), the actuator achieved the highest deflection angle of 42.7\u0026deg;, showing the most effective response. When the fin was facing upward (Fig.\u0026nbsp;\u003cspan refid=\"Fig14\" class=\"InternalRef\"\u003e14\u003c/span\u003eb), the deflection decreased slightly to 39.7\u0026deg;, which may be due to resistance opposing the natural movement. In the case with no fin (Fig.\u0026nbsp;\u003cspan refid=\"Fig14\" class=\"InternalRef\"\u003e14\u003c/span\u003ec), the deflection was the lowest at 32.2\u0026deg;, suggesting a lack of support and directional control. These findings highlight the importance of fin orientation, where aligning the fin with the bending direction can significantly enhance the flexibility and overall actuation performance of the soft robotic finger.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig15\" class=\"InternalRef\"\u003e15\u003c/span\u003e also illustrates the deflection radius for the three fin variations. The specimen with the downward-facing fin displayed a consistent and well-distributed bending, indicating a more uniform distribution of actuation forces. In contrast, the specimen without fin exhibited noticeably lower bending capability compared to the other two configurations. This result demonstrates that the presence of a fin significantly enhances the actuator\u0026rsquo;s bending performance, with the downward-facing fin, which is oriented in the same direction as the bending motion, providing the most effective deformation for finger gripper applications. These findings are consistent with our previous study [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e], which emphasized the importance of fin in optimizing the bending behavior of 4D printing gripper fingers.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec14\" class=\"Section2\"\u003e\u003ch2\u003e3.5. ANOVA Results\u003c/h2\u003e\u003cp\u003eIn this study, ANOVA was conducted to evaluate the influence of experimental variables on the finger gripper deflection performance. The factors and corresponding response variables used in the analysis are listed on Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e. For the deflection angle, the ANOVA results presented in Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e show that both the setup configuration and the applied current have a statistically significant effect, indicating that each factor plays a meaningful role in influencing the bending behavior. The setup factor, which refers to the experimental configuration, demonstrated an F-value of 84.67 and a P-value of 0.002 below the significance threshold (α\u0026thinsp;=\u0026thinsp;0.05), indicating its strong impact on the deflection. Similarly, the current factor had an F-value of 121.08 and a P-value of 0.001, which further highlights its significant role in the deflection behavior. The low P-values for both factors confirm that these variables meaningfully contribute to the variation in deflection angle. On the other hand, the effects of setup and current on the deflection radius were also investigated and presented in Table\u0026nbsp;\u003cspan refid=\"Tab6\" class=\"InternalRef\"\u003e6\u003c/span\u003e. The setup factor has an F-value of 10.95 with a p-value of 0.042. This indicates that different setup configurations result in significant variations in the deflection radius. Conversely, the current factor has a lower F-value of 5.12 and a p-value of 0.108, suggesting that the current variations do not significantly affect the deflection radius within the tested range.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eAnalysis of Variance for Deflection Angle\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSource\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDF\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eAdj SS\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eAdj MS\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eF-Value\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eP-Value\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSetup\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e237.24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e118.618\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e84.67\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.002\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCurrent\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e339.25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e169.624\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e121.08\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eError\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e4.20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.401\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTotal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e458.000\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab6\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 6\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eAnalysis of Variance for Deflection Radius\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSource\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDF\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eAdj SS\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eAdj MS\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eF-Value\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eP-Value\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSetup\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2662.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1331.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e10.95\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.042\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCurrent\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1246.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e623.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e5.12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.108\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eError\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e364.48\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e121.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTotal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e3977.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eTo validate the assumptions underlying the ANOVA, residual plots for both deflection angle (Fig.\u0026nbsp;\u003cspan refid=\"Fig16\" class=\"InternalRef\"\u003e16\u003c/span\u003e) and deflection radius (Fig.\u0026nbsp;\u003cspan refid=\"Fig17\" class=\"InternalRef\"\u003e17\u003c/span\u003e) were analyzed. For both responses, the normal probability plot of residuals shows that most data points lie close to the reference line, indicating that the residuals are approximately normally distributed. The histogram of residuals supports this interpretation, showing a roughly symmetric distribution centered around zero. Furthermore, the residuals versus fitted values plot displays a random scatter without any obvious patterns, suggesting that the assumption of homoscedasticity (constant variance of residuals) is satisfied. The residual versus observation order plot also shows no discernible trend, indicating that the observations are independent and free from autocorrelation. Overall, the statistical analysis confirms that both Setup and Current significantly affect the deflection angle and deflection radius.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eThe main effects analysis on Fig.\u0026nbsp;\u003cspan refid=\"Fig18\" class=\"InternalRef\"\u003e18\u003c/span\u003ea and \u003cspan refid=\"Fig18\" class=\"InternalRef\"\u003e18\u003c/span\u003eb reveals that both the setup configuration and the applied current significantly influence the deflection angle and deflection radius of the gripper finger. For the deflection angle, Setup 2 resulted in the highest average value, indicating superior bending performance compared to Setups 1 and 3. This suggests that the configuration of Setup 2 may provide better heat distribution or wire alignment, leading to more effective actuation. In terms of current, a clear increasing trend was observed where higher currents produced greater deflection angles, with the maximum observed at 5.2 A. This confirms that increased electrical input enhances the activation of the Nitinol wires, thereby improving bending performance.\u003c/p\u003e\u003cp\u003eFor the deflection radius, a contrast pattern exists. Setup 3 produced the largest average radius, suggesting a wider and less effective curvature, while Setups 1 and 2 achieved tighter bends, which are more desirable for gripping applications. The effect of current on the radius was nonlinear since the radius increased at 4.0 A but sharply decreased at 5.2 A. This reduction in radius at higher current levels indicates a tighter curvature, aligning with the increased deflection angle observed.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eThe interaction plots further on Fig.\u0026nbsp;\u003cspan refid=\"Fig19\" class=\"InternalRef\"\u003e19\u003c/span\u003e further support the significant influence of both setup configuration and current level on the deflection behavior. For deflection angle, Setup 2 exhibited the most responsive behavior to increasing current, achieving the highest deflection across all current levels. This indicates that Setup 2 not only performs better in isolation but also amplifies the effect of higher current more effectively than other setups. In contrast, Setup 3 consistently yielded lower deflection angles, showing limited responsiveness to current changes. For deflection radius, the interaction effect is equally notable. Setup 2 displayed a steady decrease in radius with increasing current, suggesting a progressive improvement in bend tightness as an essential characteristic for gripping applications. While Setup 1 followed a similar trend with smaller magnitude, Setup 3 demonstrated an unusual pattern which started with a significantly wider bend and only achieved a tighter radius at the highest current level. Overall, Setup 2, which uses 3 nitinol wires, 3 power supplies with 5.2 A current (Experiment 6) produced both a large deflection angle and a relatively small deflection radius. This combination suggests that Setup 2 offers a strong and tight bending motion, making it more effective for gripping tasks.\u003c/p\u003e\u003c/div\u003e"},{"header":"4. Conclusion","content":"\u003cp\u003eThe self-actuating finger gripper system design has successfully applied into the finger and activated the gripper through heat stimulus induced by the nitinol wires. This study concludes that both the experimental setup and applied current significantly affect the deflection behavior of the soft robotic finger. Among the three configurations, Setup 2 using three Nitinol wires and three power supplies consistently achieved the highest deflection angles and tightest bending radius, especially at 5.2 A, making it the most effective for gripping applications. In contrast, Setup 3 showed lower performance due to uneven heat distribution from a single power supply. ANOVA results confirmed that setup and current significantly influenced deflection angle, while only setup significantly affected the radius. Additionally, the fin orientation also proved to be a key factor, with the downward-facing fin leading to better and more consistent bending.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe would like to express our gratitude to the Institution of Mechanical Engineers (IMechE) for this project\u0026rsquo;s financial support through the research grant of IMechE SEAR Mini Research Grant 2024-2025. All the facilities and support in this project were also provided by the Center for Research and Community Services at Sampoerna University Indonesia.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eMy manuscript has no associated data in a data repository.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting Interest\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFunding: the corresponding author received research grant from Institution of Mechanical Engineers (IMechE) SEAR Mini Research Grant 2024-2025. Other authors have no relevant financial or non-financial interests to disclose.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eKushendarsyah Saptaji\u003c/strong\u003e: Conceptualization, Methodology, Supervision. \u003cstrong\u003eAzhari Tumada\u003c/strong\u003e: Literature review, Experiment, Writing-original draft preparation. \u003cstrong\u003eOctarina Adiati Juniasih\u003c/strong\u003e: Writing-original draft preparation. \u003cstrong\u003eAzmir Azhari\u003c/strong\u003e: Writing- Reviewing and Editing. \u003cstrong\u003eMebrahitom Asmelash\u003c/strong\u003e: Writing- Reviewing and Editing,\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eY. S. Alshebly, M. Nafea, M. S. Mohamed Ali, and H. A. F. 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April, p. 100271, 2022.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"4D printing, Shape memory polymers, Finger gripper, nitinol wire, heat conduction wire; deflection angle, deflection radius","lastPublishedDoi":"10.21203/rs.3.rs-7060696/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7060696/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e4D printing, utilizing the fourth dimension of time, allows for the creation of time-dependent objects that can morph and adapt. This capability has shown great potential in soft robotics, particularly in developing soft actuators for adaptive movement. Heat-sensitive shape-memory polymers are a key component in this process, enabling programmed shape changes in response to temperature change. In this study, the heat induced wire is used as the heat stimulus for the 4D printed self-actuator finger. The objectives are to observe the effect of current, temperature, and wire arrangement to the deflection of self-actuator finger, and to obtain the optimum parameters for actuation. The deflection angle and the deflection radius are measured in this study to evaluate the finger performance aiming for a larger deflection angle and a smaller curvature radius. In addition, the effect of the fin on the deflection is also observed. An ANOVA method was used to statistically determine the significant effects of the current, temperature and wire arrangement and to obtain the optimum parameters. Result shows that current, temperature, and wire arrangement all have significant impacts on deflection. The 5.2 Ampere current offers better deflection results compared to 4 Ampere or lower. When the temperature exceeds the PLA's glass transition temperature in the wire, the specimen deflects according to the programmed direction. Additionally, utilizing 3 nitinol wires resulted in greater deflection than using 2. The optimal parameters for maximum deflection are 3 power supplies, 3 nitinol wire, and 5.2 amperes. Furthermore, a design with fins achieves better deflection compared to a design without fins.\u003c/p\u003e","manuscriptTitle":"Assessing Heat-Driven 4D Printed Finger Actuators with Conductive Wires: A Parametric Analysis","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-07-14 15:18:05","doi":"10.21203/rs.3.rs-7060696/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"5dd7f492-b176-49f2-aec6-62a98107a87e","owner":[],"postedDate":"July 14th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-09-03T20:31:47+00:00","versionOfRecord":[],"versionCreatedAt":"2025-07-14 15:18:05","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7060696","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7060696","identity":"rs-7060696","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}