A Piezoresistive-based 3-axial MEMS Tactile Sensor and Its Integrated Surgical Forceps for Gastrointestinal Endoscopic Minimally Invasive Surgery

A Piezoresistive-based 3-axial MEMS Tactile Sensor and Its Integrated Surgical Forceps for Gastrointestinal Endoscopic Minimally Invasive Surgery | 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 Article A Piezoresistive-based 3-axial MEMS Tactile Sensor and Its Integrated Surgical Forceps for Gastrointestinal Endoscopic Minimally Invasive Surgery Huicong Liu, Cheng Hou, Huxin Gao, Xiaoxiao Yang, Guangming Xue, and 6 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4483564/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 9 You are reading this latest preprint version Abstract In robotic-assisted surgery (RAS), traditional surgical instruments without sentient capability cannot perceive accurate operational forces during the task, and such drawbacks can be largely intensified when conducting sophisticated tasks using flexible and slender arms with small end-effectors, e.g., in gastrointestinal endoscopic surgery (GES). In this work, we propose a micro-electro-mechanical systems (MEMS) piezoresistive 3-axial tactile sensor for GES forceps, which can intuitively provide surgeons with online force feedback during robotic surgery. The fabrication process of MEMS enables the sensor chips to possess dimensions of miniaturization. The fully encapsulated tactile sensors can be effortlessly integrated into miniature GES forceps, which feature a slender diameter of just 3.5 mm and undergo meticulous calibration procedures least squares method. In experiments, the sensor's capability to accurately measure directional forces up to 1.2 N in Z axis was validated, demonstrating an average relative error of only 1.18% compared to the full-scale output. The results indicate that this tactile sensor can provide effective 3-axial force sensing during surgical operations, such as grasping and pulling, and in ex-vivo testing of the porcine stomach. Its characteristics of compact size, high precision, and integrability establish solid foundations for clinical application in the operating theatre. Physical sciences/Engineering/Electrical and electronic engineering Physical sciences/Nanoscience and technology/Nanoscale devices/Sensors Physical sciences/Nanoscience and technology/Other nanotechnology/Environmental, health and safety issues Robotic-assisted surgery Gastrointestinal endoscopic surgery Piezoresistive-based tactile sensor MEMS Force sensing Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 1. Introduction Advancements in medical technology have positioned robotic-assisted surgery (RAS) as a crucial sector that can comprehensively enhance surgical precision and efficiency 1–6 . Recently, RAS has been evolving towards Single Port Laparoscopy 7 (SPL) and Natural Orifice Transluminal Endoscopic Surgery 8,9 (NOTES), aiming to lessen patient invasiveness, hasten recovery, and reduce complication risks 7–9 . SPL, conducted through a single, small incision, significantly reduces the number and size of surgical incisions, thereby easing patient recovery and improving cosmetic results post-operation 10 . NOTES introduces instruments via natural orifices, avoiding abdominal cuts, leading to nearly invisible scars, quicker recovery, and lower infection risks 11 . These designs include highly flexible, multi degree of freedom (DOF), and miniaturized manipulators for skilled operations 1 . In NOTES, a prevalent practice involves the removal of early-stage neoplastic tissues via gastroscopy, including techniques like Endoscopic Submucosal Dissection (ESD). This method employs flexible endoscopes, either single- or dual-channel, to navigate the complex and winding paths of the gastrointestinal tract for surgical interventions. Figure 1 a illustrates the developed surgical instrument 12,13 , equipped with a multi-DOF manipulator designed for gastrointestinal endoscopic procedures. This manipulator is adept at manipulating tissues through an endoscope's 3.8 mm work channel and features an external diameter of less than 3.5 mm 12 . However, the lack of force sensing in surgical leading to heavy reliance on visual observation and experience 4,14–17 . This gap can cause excessive force application, risking damage to sensitive tissues and increasing surgical errors; therefore, it is crucial to introduce instruments with force sensing capabilities to improve surgical accuracy and safety 1,5 . Additionally, integrating force sensing is vital for preventing tissue slippage, thereby boosting procedural efficiency 18–20 . To address this issue, force/tactile sensors and actuators have been integrated as essential components of RAS systems. In some recently studies, sensors are commonly integrated into the joint drive units of surgical instruments to indirectly estimate interaction forces by analyzing the responses of the drivers 14,21 . Nonetheless, measurement accuracy is affected by mechanical factors like coupling, friction, and gravity 2,22–25 . To counteract this, direct sensor placement has been explored at critical points such as the instrument's abdominal axis, wrist joints, and the tip's direct contact areas with tissue, enhancing force measurement precision as proximity to tissue increases 2,6,23,25 . This shift underlines the growing focus on embedding tactile sensors directly onto minimally invasive surgical (MIS) instruments' tips and joints for more accurate force detection 23,25 , utilizing electrical piezoresistive 2–4,6,17,26–28 , piezoelectric 29,30 , capacitive 23,25,31–34 and optical methods 35–40 . Kim et al. 23,25 and Lee et al. 31 developed capacitive-based force sensor, integrating them into surgical instruments with diameters ranging from 8 mm to 10 mm. Kuwana et al. 41 devised a piezoresistive MEMS force sensor and incorporated it into a MIS surgical instrument with an outer diameter of 12 mm. Although these solutions have addressed the lack of force sensing in surgical instruments, the instruments themselves remain relatively large. This highlights an ongoing need for further miniaturization of force sensing technologies. Researchers conducted by Yurkewich et al. 42 , Li et al. 43 , and Suzuki et al. 44 have employed Fiber Bragg Gratings (FBGs) technology, which measures strain by detecting shifts in the wavelength of light reflected from periodic gratings in an optical fiber. They integrated it at various locations on surgical instruments, such as the shaft and wrist, to enhance force sensing capabilities. However, optical fibers cannot be routed within small bending radii. Additionally, the use of small and complex components in SPL and NOTES could increase manufacturing and assembly costs. These factors highlight the challenges facing fiber-based sensor solutions. To overcome these limitations, this work introduces a miniature piezoresistive-based MEMS 3-axial tactile sensor, offering a solution for force sensing in gastrointestinal endoscopic minimally invasive surgery (GEMIS) that integrates compact sensors with high-integration and high-precision force sensing. This compact sensor, featuring a piezoresistive sensor chip equipped with four cantilever structures, encased in a protective housing with a central aperture. An elastic layer is employed to transmit external forces, and a flexible printed circuit board (FPCB) facilitates chip bonding and signal transmission. Utilizing MEMS fabrication techniques, a miniature piezoresistive chip was prepared. The fully encapsulated sensor can be seamlessly and extremely simple integrated into surgical forceps with an external diameter of 3.5 mm as illustrated in Fig. 1 a and 1 b. The sensorized forceps underwent analysis and calibration for the sensing characteristics and 3-axial forces dynamics. Repeatability tests demonstrated the sensor's exceptional stability. Calibration revealed its high resolution and minimal mean relative error, highlighting significant advantages. The efficacy of the sensorized forceps is evaluated by testing their ability to grasp and pull tissue-mimetic materials, assessing the accuracy and reliability of the forces applied. Experimental demonstration of ex-vivo porcine stomach was performed to validate the effectiveness of the proposed 3-axial sensorized forceps based on the piezoresistive MEMS tactile sensor. 2. Results and Discussion 2.1 Design and working principle A prototype of the gastrointestinal endoscopic dissecting forceps 13 incorporating the 3-axial tactile sensor is depicted in Fig. 1 a. To accommodate 3-axial force manipulations, the sensorized forceps integrate a tactile sensor within the lower jaw, as illustrated in Fig. 1 b. The jaw is specifically designed with a slot to securely fit the sensor. In the configuration of the tactile sensor, as shown in the Fig. 1 c, it mainly composed of four components: an elastic force transfer layer, a stainless-steel case, a FPCB, and a piezoresistive sensor chip. The piezoresistive sensor chip, measuring 2.0 mm by 2.0 mm with a thickness of 0.3 mm, is designed to be sufficiently small for integration into the jaw. In this sensor, it is bonded and wired to the FPCB and leads the analog signal through the FPCB’s gold wire. The case with a size of 2.7 mm × 4.5 mm is fixed with the FPCB, which has an inner cavity that completely covers the chip. Thus, it can protect the bonding gold wires between the chip and FPCB. The elastic force transfer layer is attached to the surface of the case, while the column in the transfer layer is attached to the chip and in contact with the four cantilevers. Hence, external forces are allowed to make indirect contact with the sensitive cantilevers through the middle hole of the case. This rigid-flexible coupling structure enhances the sensitivity and accuracy of force signal transmission, while its integrated and modular architecture facilitates mass production and ensures robust environmental adaptability. In this design, the FPCB with dimensions of 1.8 m in length, 1 mm in width, and 0.1 mm in thickness, has a significant advantage as the gold flat cable can bypass the tail of the jaw and travel through the entire flexible manipulator via the inner cavity. Accordingly, it can move freely in its inner cavity when the manipulator is operated. The piezoresistive tactile sensor, which detects forces based on the resistance change of piezoresistors due to its deformation under external forces. In this proposed sensor, the elastic layer functions as a cover that protects the cantilevers and interacts with the target tissue. The top view of the sensor chip is shown in Fig. 1 d, two rectangular piezoresistors positioned in the vertical direction (denoted as R2 and R4) and two more positioned in the horizontal direction (denoted as R1 and R3) (Figure S1 a, Supporting information). Each piezoresistor consists of two rectangular piezoresistors (red block), with the size of 5 µm × 60 µm, and the resistances are concentrated in the stress concentration area (Figure S1 b, Supporting information). The external forces exerted on the elastic layer are conveyed to the cantilevers via the intermediary column. In this arrangement of piezoresistive cantilevers and columns, the responses of each piezoresistive element generate distinct outputs. These allow for the independent characterization of stresses associated with external forces, specifically normal and shear forces. As depicted in Fig. 1 e, under normal force, identical compressive deformations at each of the four cantilevers yield similar strain-induced changes in resistances of the four piezoresistive elements. Uniaxial shear force applied along the direction of X-axis leads to strain difference of two coaxial cantilevers, i.e., a correspondingly large increase in resistance of R3 and a corresponding small increase in resistance of R1, while with negligible strain difference of the other two cantilevers along the Y-axis of R2 and R4. When the forceps grasp an object, the upper and lower jaws close, and the grasped object applies a downward force on the elastic layer, resulting in the compression of the tactile sensor. Subsequently, the cantilevers of the sensor deform, leading to changes in resistances. The signal wires are routed from the back of the sensor and extend through the shaft of the forceps to the end, as illustrated in Fig. 1 a and 1 b. 2.2. Fabrication and assembly process Figure 2 a illustrates the detailed fabrication process of the sensor chip. The procedure commences with an n-type, (100)-oriented silicon-on-insulator (SOI) wafer, utilized as the initial substrate, featuring a device layer thickness of 5 µm. Initially, SiO 2 layers were thermally grown on both sides of the wafer. Subsequent steps included the photolithography process on the wafer's front side to delineate the piezoresistors. This was followed by the implantation of boron ions at a dosage of 5 × 10 14 cm − 2 . Rapid thermal annealing (RTA) was then applied to activate the dopants, thereby forming the piezoresistors. A subsequent boron ion implantation was carried out with a dosage of 2 × 10 15 cm − 2 , followed by an RTA step to establish ohmic contacts. Aluminum was then sputtered and patterned to a thickness of 700 nm, facilitating the metallization required for interconnections with the piezoresistors. Precise regulation of the diffusion temperature and duration enabled consistent and efficient doping, achieving less than 2% variability in the mean value across four cantilevers within a single batch (Figure S1 c, Supporting Information). Plasma Enhanced Chemical Vapor Deposition (PECVD) was employed to deposit a 1 µm layer of silicon nitride (SiN x ), which served to offset the compressive stress within the SiO 2 layer and protect the surface electrodes. The fabrication continued with the opening of contact pads and the patterning and etching of cantilevers. Backside deep reactive ion etching (DRIE) was conducted to release the cantilever structure down to the buried oxide (BOX) layer. Subsequently, the buried SiO 2 layer was removed via reactive ion etching. The final sensor chip, measuring 2.0 × 2.0 × 0.3 mm 3 , is depicted in Fig. 2 b, positioned on an index finger. The cantilever structures are distinctly visible in the scanning electron microscope (SEM) image shown in Fig. 2 c. In addition to the piezoresistive sensor chip, the elastic force transfer layer is also crucial, since it can transmit external excitation to the sensitive cantilevers, also serves as an encapsulation. A stainless-steel mold shown in Fig. 2 d and Figure S2 (Supporting information) is needed to form the column structure, thus it can pass through the case’s hole (Fig. 1 c) and contact with the sensor’s cantilevers. The height of the column becomes the focus in order to ensure that the column and the cantilevers can also be in proper contact in load free. While the height of the column is determined by the following factors: the height of the sensor chip (300 µm), the height of the case (500 µm). Hence, the height of the column is determined as 200 µm. Pouring the Polydimethylsiloxane (PDMS, Sylgard184, Dow Corning Corp) with a mixture ratio of 10:1 (PDMS polymer base: polymerization agent) into the machined mold. Sort it in a vacuum box for 10 minutes to eliminate bubbles, subsequently heat 15 minutes at 100 ℃ in oven. Pay special attention to pressing a glass plate on the surface of the PDMS so that it can ensure a flat surface. After that, lift out to obtain the elastic layer, resulting in a Young’s modulus of approximately 2.61 MPa of the transfer layer 6 (Table S1 , Supporting information). Finally, the final elastic layer with dimensions of 4.5 mm × 2.7 mm and a central column of 1.6 mm × 0.2 mm is produced (Figure S2, Supporting information). In adherence to the outlined specifications, the sensor-integrated jaw has been meticulously crafted. The main body and housing are constructed from 304 stainless steel, endowed with a Young's modulus of 200 GPa, ensuring robustness and durability. The gripping section of the jaw body spans a length of 8.0 mm, and upon closure, the total external diameter of the conjoined jaws remains below the 3.5 mm threshold (Figure S3, Supporting information). This compact design facilitates seamless insertion through the endoscope's 3.8 mm diameter working channel. Coupling this sensor-equipped jaw with an external 3.5 mm flexible manipulator enables precise navigation and operation under endoscopic control. The piezoresistive sensor chip, is meticulously bonded to the FPCB with a height of 0.1 mm. A stainless-steel sheet, also 0.1 mm thick, reinforces the sensor's stationary region to prevent deformation and maintain sensor integrity. Figure 2 e (i) shows the sensor fixed on the FPCB and a case. Place the case over the sensor chip while making sure that the sensor's sensitive unit is fully transparent to the case’s hole, as shown in Fig. 2 e (ii). The encasing measures 2.7 × 4.5 × 0.6 mm 3 , tailored to slot into the lower jaw with precision. Once inserted, the tactile sensor is anchored in place using silicone gel, ensuring a secure and stable assembly, as shown in Fig. 2 e (iii). Finally, the upper and lower jaw are connected to the flexible manipulator using a hinge pin, shown in Fig. 2 e (iv). This methodical assembly ensures that the sensorized forceps are equipped with a 3-axial force sensing capability, primed for complex surgical procedures. Table 1 Comparison of different force perception methods in MIS Study Method and location Instrument D (mm) Kim et al. 23,25 Capacitive-based transducers integrated into the grasper S-Surge Surgical Robot 8 Lee et al. 31 Capacitive-based sensor integrated into wrist and instrument base RAVEN-II 10 Kuwana et al. 41 Piezoresistive-based sensor integrated into grasper MIS laparoscopic grasper 12 Yurkewich et al. 42 FBGs-based sensor integrated into distal shaft and gripper MIS arthroscopic grasper 4.57 Li et al. 43 FBGs-based sensor integrated into articulated wrist Palpation probe 4 Suzuki et al. 44 FBGs-based sensor near the tip of forceps Bilateral micro-operation system 4 This work Piezoresistive-based sensor integrated into the forceps GEMIS 3.5 Figure 2 f illustrates a gastrointestinal endoscopic device featuring two work channels: a 2.7 mm channel for an electric knife (dual knife) and a 3.8 mm channel for a flexible manipulator, along with a light source and lens. During procedures, the dual knife and flexible manipulator are inserted through these channels to the target area to perform electro-dissection (electro-coagulation) and grasping tasks. The light source illuminates the confined surgical field, and the lens provides visual feedback. The sensorized forceps, integrated into the flexible manipulator's tip, facilitate 5-DOF movements including grasping, pitching, yawing, rolling, and advancing 12,13 . Table 1 compares this sensor's integrated instruments with previous studies, clearly demonstrating that the surgical digestive endoscopy forceps integrated with this sensor have the smallest external diameter, measuring only 3.5mm. 2.3. Force sensing characterization and calibration Upon the successful fabrication of the sensor-integrated forceps, a calibration experimental setup was established, as depicted in Fig. 3 a. A commercial 6-axis force/torque sensor (Nano 17, ATI), mounted on a 3-DOF linear stage, served as the reference for measurements. The reference sensor was connected to an amplifier and a data acquisition system (NI-USB 6210, DAQ). Analog signals from the sensor were conditioned by electrical circuitry, where they were filtered and amplified before digitization by the DAQ and subsequent transmission to the computer. The sensor's electrical circuit employs a wheatstone bridge with three fixed resistors, each matched to the piezoresistor's initial resistance (Figure S4, Supporting information). External forces alter the piezoresistor's resistance, unbalancing the bridge. This imbalance induces a voltage change, which is then amplified by AD620. An AD705 serves as a buffer to the amplifier, stabilizing the output voltage at 2V when the bridge is balanced. The circuit's final output is directed to the DAQ (NI-USB 6210), and recorder through the data acquisition procedure (Figure S5, Supporting information). This setup allows for the capture of voltage signals from the four piezoresistors, enabling the computation of resistance changes and corresponding voltage fluctuations in each cantilever. In the front and top view of the calibration setup, as shown in Fig. 3 a, the 3-DOF stage exerts three orthogonal forces F X , F Y , and F Z onto the lower jaw of the forceps via its triaxial motion capabilities through one 3D printing jig. During the experiments, the measured voltage data and the reference data were recorded simultaneously. To evaluate the performance of the tactile sensor, normal force and shear force testing including the loading and unloading process were conducted. During the process, the experiments were repeated about 90 times along the Z axis. Figure S6 (Supporting information) shows the four cantilevers raw data without filter which has affirmed the sensor’s outstanding repeatability. Applying the Kalman filter method to the raw voltage data results in a smoother curve (Figure S7, Supporting information). Figure 3b1 shows six repeated curves of the cantilevers as a function of normal force from 0 to 1.2 N, while Figs. 3b2 and 3b3 display three repeated curves of the four cantilevers as a function of lateral force along the X and Y axes from − 0.6 to 0.6 N, respectively. To best meet the design requirements of surgical instruments, efforts have been made to achieve a grasping force of 0.77 N and a traction force of 0.71 N 12 . While there is potential for further increasing the calibrated normal force, a normal force of 1.2 N is sufficient to prevent the lower jaw from slipping when the shear force is increased to 0.6 N, thus ensuring effective calibration. Although the 0.6 N shear force is slightly below the target value, the data still meet the requirements for procedures such as Endoscopic Submucosal Dissection (ESD). The voltages versus normal force relationships of four cantilevers are presented in Fig. 3c1, c2, c3 and c4 with a 95% confidence interval. The series of repeated tests conducted has affirmed the sensor's outstanding repeatability, evidenced by the majority of voltage readings aligning within the prescribed confidence intervals. This consistency furnishes credible data underpinning the sensor's calibration process. To measure the quantitative values of forces, bridging the gap between the voltage variances of four cantilevers and the 3-axial forces based on proper calibration is essential. Figure 3d1, d2 and d3 shows the tendencies of the four cantilevers' voltage data of the forceps based on the reference data. In the graphs, the data points for voltages correspond to the mean of repeated measurements, ranging from 0 to 1.2 N along the Z-axis and from − 0.6 to 0.6 N along the X and Y axes. As shown in Fig. 3d1, the four voltages are changed in the same direction. The voltages increase by the external force from 0 to 1.2 N. At the same time, the voltage data for the four cantilevers exhibit almost uniform variations. Externally applied forces in the X-direction induce significant voltage changes in cantilevers 2 (V 2 ) and 4 (V 4 ), which are aligned with the X-axis, whereas cantilevers 1 (V 1 ) and 3 (V 3 ), oriented along the Y-axis, exhibit minimal voltage variations, as shown in Fig. 3d2. The trends in voltage shifts for cantilevers 2 and 4 are entirely antithetical. The modest voltage fluctuations observed in cantilevers 1 and 3 are primarily attributable to assembly inaccuracies. Conversely, the shear forces applied in the Y-direction yield an inverse response, as shown in Fig. 3d3. As a result, the tendencies of the measured voltages with respect to the external 3-axial forces are consistent with the explanation provided of the working principle. For the purpose of calibrating the 3-axial forces from the voltage data after filtering, it was imperative to establish a calibration matrix. Given the observed good linearity of voltage responses of the four cantilevers under the application of triaxial forces, this matrix was deduced utilizing the linear least squares method (see Text S1, Supporting information), which provides a correlation between the external 3-axial forces and the corresponding voltage readings. The calibration matrices \(A\) is calculated as: $$A= \left[\begin{array}{cc}\begin{array}{cc}-0.1411& 0.48225\\ 0.25225& 1.01904\\ 0.33861& 1.28641\end{array}& \begin{array}{cc}-0.2460& 0.77293\\ 0.10931& -1.3922\\ -2.4574& 0.88168\end{array}\end{array}\right]$$ 1 Thus, the 3-axial forces \({\left[\begin{array}{ccc}{F}_{X}& {F}_{Y}& {F}_{Z}\end{array}\right]}^{T}\) can be calculated through the equation: \(A·{\left[\begin{array}{cc}\begin{array}{cc}{V}_{1}& {V}_{2}\end{array}& \begin{array}{cc}{V}_{3}& {V}_{4}\end{array}\end{array}\right]}^{T}\) . In consequence, the calibrated 3-axial forces measured by the sensorized forceps with respect to the reference force can be seen in Fig. 3 e, in which e1 for the Z-axis force, e2 for the X-axis force, and e3 for the Y-axis force. The experimental findings enabled the determination of the force resolution for the tactile sensor, which was established as 0.66 mN, 0.61 mN, and 0.28 mN for the respective axes. The mean relative error was calculated to be 1.15%, 2.43%, and 1.18% of the full-scale output (FSO) force ranges, corresponding to each axis. The sensor's performance are listed in Table 2 . For detailed calculation description, see text S1, S2, and S3 (Supporting information). Table 2 Performance of the developed 3-axial tactile sensor of the sensorized forceps Quantity Value Unit X-axis Y-axis Z-axis Force range 0.6 0.6 1.2 N Force resolution 0.66 0.61 0.28 mN Mean relative error 1.15 2.43 1.18 % of FSO *FSO: Full scale output force range 2.4. Experimental validations of sensorized forceps In RAS, the use of forceps can be categorized into two main scenarios: grasping and pulling. Grasping primarily involves the application of normal forces, whereas pulling mainly involves the application of shear forces. Two distinct types of materials are used to simulate two radically different tissues within the gastrointestinal tract. PDMS with a doping ratio of 30:1 (Young’s modulus of 0.86 MPa, Table S1 , in Supporting information) is used to simulate tumor tissues such as gastric adenocarcinoma or gastrointestinal stromal tumors, which are generally harder and have a different texture compared to the gastric mucosa. To simulate the conditions of gastric mucosa during gastrointestinal surgeries, thermoplastic rubber (TPR) is selected as the demonstration model for the integrated system verification. Initially, the forceps perform three grasping actions on the simulated tumor tissue, followed by a pulling action along the X-axis. Subsequently, the forceps grasp the simulated tumor tissue and move it along the Y-axis direction, thereby evaluating the capability to detect forces in different directions. During this process, data collection occurs at a sampling frequency of 1000 Hz, and the obtained three-axis force values are presented in Fig. 4 . It warrants emphasis that, as the forceps incrementally engage with the simulated tumor tissue, the concurrent generation of both shear and normal forces ensues, as shown in Fig. 4 a. The forceps also exhibit commendable responsiveness to pulling actions on tissues in both the X and Y directions. However, during the pulling of tissue in the Y direction, since the traction on the tissue does not occur purely along the Y-axis but is accompanied by a component in the X direction, there is also a significant response in \({F}_{X}\) with each action, as shown in Fig. 4 c. Due to the softer nature of simulated gastric mucosa (TPR), it is easier to discern the applied actions from its deformation during grasping and pulling. The grasping and pulling actions are illustrated from Fig. 5a1 to 5e1, with the force values response at various stages shown in Fig. 5a2 to 5e2. As the forceps grasp the simulated gastric mucosa, the three-axis forces begin to be displayed in Fig. 5b2, with \({F}_{Z}\) showing the most significant increase. Upon pulling in the X direction, the \({F}_{X}\) value increases; when the pulling stops, the \({F}_{X}\) value decreases. As pulling continues, \({F}_{X}\) increases further. During the pulling process, the tissue begins to slip within the forceps, and the amount of simulated mucosa gripped by the forceps continuously decreases, as shown in Fig. 5d2. When a sudden drop in \({F}_{X}\) occurs in Fig. 5e2, it indicates that the simulated mucosa has lost effective grip within the forceps and needs to be regripped. Although TPR is sufficiently soft to simulate gastric mucosa, it still differs significantly from actual gastric mucosa. Consequently, we prepared a fresh porcine stomach and randomly selected an area on the gastric body for marking and circumcising. We then used the sensorized forceps to grasp and pull the circumcised gastric mucosa, assessing the effectiveness of these forceps in a real porcine stomach test. The ex vivo experiments on a porcine stomach is depicted in Fig. 6 a. During the experiment, an assistant positioned the flexible arm at an appropriate location on the stomach body, while the operator controlled the arm's movement and the forceps’ opening and closing with their main hand to grasp and pull the pre-circumscribed lesion. The grasping and pulling actions are illustrated from ① to ④, with the voltage values and force values response at various stages shown in Fig. 6 b and 6 c. Throughout the grasping and pulling process, changes in three-dimensional forces occur, particularly at the initiation of grasping, the beginning of pulling, and when slippage occurs. The maximum grasping force during the process is approximately 0.17 N, which is significantly lower than the forces observed when grasping PDMS and TPR. Unlike grasping TPR, the value of \({F}_{X}\) inversely increases when grasping actual gastric mucosa, and the absolute value of F X decreases as pulling continues. This is primarily due to the irregular shape of the gastric mucosa. Compared to \({F}_{X}\) and \({F}_{Z}\) , the forces \({F}_{Y}\) is smaller. Feedback on the entire process of force changes is provided to the operator, who can then feel the progression of these changes and determine the actions of clamping and pulling. 3. Conclusion This work introduces a compact piezoresistive MEMS 3-axial tactile sensor for GEMIS. This tactile sensor, characterized by its innovative design, incorporates a piezoresistive chip with four cantilever structures housed within a protective casing featuring a central aperture. An elastic force transfer layer is utilized for the transmission of external forces, while a FPCB ensures efficient chip bonding and signal transmission. The meticulous application of MEMS process flow techniques facilitated the creation of a miniature piezoresistive chip, measuring just 2.0 × 2.0 × 0.3 mm 3 . The fully encapsulated sensor, with overall dimensions of 4.5 × 2.7 × 0.6 mm 3 , demonstrates the feasibility of its integration into surgical forceps with an external diameter of 3.5 mm, offering a straightforward and seamless incorporation process. The study further delves into a comprehensive analysis and calibration of the sensorized forceps, focusing on their sensing characteristics and 3-axial force dynamics. Through repeated tests, the tactile sensor showcased exceptional stability, with calibration results revealing its superior resolution as high as 0.28 mN in \({F}_{Z}\) and minimal average relative error down to 1.18% of FSO. These findings underscore the sensor's significant advantages, particularly in terms of its performance and reliability. Moreover, the practical application and effectiveness of the sensorized forceps were assessed through tests involving the manipulation of tissue-mimetic materials and ex vivo of porcine gastric. These tests, aimed at evaluating the accuracy and reliability of both grasping and pulling forces, demonstrated the sensor's potential in enhancing the precision and efficacy of surgical procedures. In future work, we will further focus on optimizing and minimizing the sensor design to enhance its versatility and broaden its potential applications in NOTES, especially the application in the DREAMS (Dual-arm Robotic Endoscopic Assistant for Minimally Invasive Surgery). Additionally, animal clinical trials will be conducted to assess the feasibility and effectiveness of the sensor in a clinical environment. 4. Experimental Section 4.1 Description of the amplifier circuit for analog signals Figure S4 illustrates the amplifier circuit employed for the sensor, with the detailed schematic of the individual circuit shown on the right. The circuit operates with a 5V power supply and incorporates three fixed resistors within the Wheatstone bridge, calibrated to match the resistance of the initial piezoresistor value. When subjected to external forces, the resistance of the piezoresistor changes, thereby disturbing the balance of the Wheatstone bridge. The resultant voltage output from the bridge is subsequently amplified by the AD620 operational amplifier, which has a gain factor of 19.93 and an RG resistance of 2611 Ω. To achieve an initial output voltage of 2 V in the balanced state, the AD705 is employed as a follower to the amplifier chip. The output of the circuit is then directed to the analog input of a data acquisition system (DAQ), specifically the NI-USB 6210. Consequently, voltage signals from the four piezoresistors are available, enabling the computation of resistance changes (ΔR) and voltage variations in each direction. 4.2 Description of the signal acquisition system based on LabView To ensure real-time and accurate voltage data acquisition from the sensorized forceps and the standard sensor, a real-time data acquisition and display interface was developed based on LabVIEW, as shown in Figure S5a. This interface allows for the real-time display of voltage changes in the force-sensing clamp due to the piezoresistive effect. The LabVIEW display interface juxtaposes the signal data from the sensorized forceps and the ATI Nano17, facilitating a more intuitive comparison of their signal responses. This not only enhances the display quality but also enables the synchronous acquisition of time-domain signals from both sensors. The detailed acquisition interface is shown in Figure S5b, where the upper section displays the force/torque information from the standard sensor, and the lower section shows the unfiltered voltage signals from the sensorized forceps. 4.3 Preparation of gastric corpus mimic lesions First, rinse the inner and outer walls of the pig stomach with clean water and place the stomach into a stainless-steel tray. The bottom of the tray is equipped with the negative electrode plate required for the high-frequency electric knife. Use the coagulation function of the electric knife to mark the area around the gastric body before circumcision. After marking, use the electric knife to cut along the outer edge of the marks and continue cutting the mucosal tissue below the inner wall of the circumscribed area to complete the simulation of the lesion. Declarations Competing interests: The authors declare no other competing interests. Data and materials availability All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials. Additional data related to this paper may be requested from the authors. Author contributions C.H. conceived the tactile sensor idea and operation principle. C.H. and H. L. developed fabrication processes based on previous work. C. H. fabricated and characterized the devices and performed all data collection and analysis. C.H. prepared figures, drawings, and schematics. C.H. and B. L. took SEM pictures. H.L., together with C.H., H. G, and X. Y. performed experiments related to robotics. C.H. drafted the manuscript. All authors discussed the results and commented on the manuscript. H.L. and B. L. provided a critical revision of the article. C.H. and B. L. revised the manuscript. H.L. and L.S. provided critical feedback to the development of the sensing module concept, fabrication process and materials investigations, device characterization, data interpretation, and critical revision of the article. Acknowledgments The work presented in this paper was a collaboration of all authors. This work was funded by the Natural Science Foundation of the Higher Education Institutions of Jiangsu Province, China (21KJA460006), the Natural Science Foundation of Jiangsu Province of China (BK20220490) and the National Natural Science Foundation of China (62203315). References Dupont, P. E. et al. A decade retrospective of medical robotics research from 2010 to 2020. Science robotics 6, eabi8017 (2021). Hou, C. et al. in 2021 IEEE 16th International Conference on Nano/Micro Engineered and Molecular Systems (NEMS) 60–63 (2021). Hou, C. et al. in 2021 21st International Conference on Solid-State Sensors, Actuators and Microsystems (Transducers) 214–217 (2021). Okuda, Y. et al. 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Additional Declarations (Not answered) Supplementary Files MXNSupportinginformationv0527.docx MXN1.mov Grasping and Pulling the Simulated Tumor Tissue in X- and Y- Direction MXN2.mov Grasping and Pulling the Mimic Gastric Mucosa in X-Direction Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: revise 13 Jun, 2024 Review # 2 received at journal 08 Jun, 2024 Review # 1 received at journal 04 Jun, 2024 Reviewer # 2 agreed at journal 02 Jun, 2024 Reviewer # 1 agreed at journal 30 May, 2024 Reviewers invited by journal 29 May, 2024 Submission checks completed at journal 27 May, 2024 Editor assigned by journal 27 May, 2024 First submitted to journal 27 May, 2024 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. 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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-4483564","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":308437818,"identity":"c8fd4a3f-9195-4cdb-be84-c77dc0a5cecf","order_by":0,"name":"Huicong Liu","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA20lEQVRIie3OsQrCMBCA4SuBukRcI9o+QyQQEcVnMQhObi4dI4KT6Cz4EBVfICVDl4Br3JycOjg6CBpXkVo3h/xwQ+C+cAA+3x9GAUkF9BE33IO4CeR3EjiSINaUvxAAg0SqqpJuLZvr+jJk7Gg69gaDKFXoci4jvZWQjuCY2ynrrWDCUhV2aelhNngRwrjFnGDQ7kIckgqEisPG8OYdHhUJNiORwpS3MKgKxAiZ7RLFiJ3M+m06Zlsd8nKSa30tqIobG70/FckwWueLSyl5/8EN+mHf5/P5fJ97Ak+BTK8SBoYVAAAAAElFTkSuQmCC","orcid":"https://orcid.org/0000-0003-3651-9114","institution":"Soochow University","correspondingAuthor":true,"prefix":"","firstName":"Huicong","middleName":"","lastName":"Liu","suffix":""},{"id":308437819,"identity":"8f2fa2fe-2967-46ce-a273-1083e0e6234c","order_by":1,"name":"Cheng Hou","email":"","orcid":"","institution":"Soochow University","correspondingAuthor":false,"prefix":"","firstName":"Cheng","middleName":"","lastName":"Hou","suffix":""},{"id":308437820,"identity":"cddf0c3b-0556-4aeb-962d-5178f09f0698","order_by":2,"name":"Huxin Gao","email":"","orcid":"","institution":"The Chinese University of Hong Kong","correspondingAuthor":false,"prefix":"","firstName":"Huxin","middleName":"","lastName":"Gao","suffix":""},{"id":308437821,"identity":"2e874973-00bb-4c94-b618-c9dc904a0d0c","order_by":3,"name":"Xiaoxiao Yang","email":"","orcid":"","institution":"Shandong University","correspondingAuthor":false,"prefix":"","firstName":"Xiaoxiao","middleName":"","lastName":"Yang","suffix":""},{"id":308437822,"identity":"50d5b9a9-4f1e-4e96-b44d-8b372ba3c157","order_by":4,"name":"Guangming Xue","email":"","orcid":"","institution":"Soochow University","correspondingAuthor":false,"prefix":"","firstName":"Guangming","middleName":"","lastName":"Xue","suffix":""},{"id":308437823,"identity":"758a1d10-9488-4b29-934b-bac3d16df0dd","order_by":5,"name":"Xiuli Zuo","email":"","orcid":"","institution":"Shandong University","correspondingAuthor":false,"prefix":"","firstName":"Xiuli","middleName":"","lastName":"Zuo","suffix":""},{"id":308437824,"identity":"e861cf25-cb6e-4499-895e-c0b30c9b9dc9","order_by":6,"name":"Yanqing Li","email":"","orcid":"","institution":"Shandong University","correspondingAuthor":false,"prefix":"","firstName":"Yanqing","middleName":"","lastName":"Li","suffix":""},{"id":308437825,"identity":"50dccf6e-9e89-451c-bccc-c7fd01b6848c","order_by":7,"name":"Dongsheng Li","email":"","orcid":"","institution":"Soochow University","correspondingAuthor":false,"prefix":"","firstName":"Dongsheng","middleName":"","lastName":"Li","suffix":""},{"id":308437826,"identity":"71224fba-f0f7-4257-815f-b6e5a255cd24","order_by":8,"name":"Bo Lu","email":"","orcid":"https://orcid.org/0000-0002-2858-1121","institution":"Soochow University","correspondingAuthor":false,"prefix":"","firstName":"Bo","middleName":"","lastName":"Lu","suffix":""},{"id":308437827,"identity":"ae73fb41-f8fe-427c-bf85-e78ca7a45fe2","order_by":9,"name":"Hongliang Ren","email":"","orcid":"","institution":"The Chinese University of Hong Kong","correspondingAuthor":false,"prefix":"","firstName":"Hongliang","middleName":"","lastName":"Ren","suffix":""},{"id":308437828,"identity":"ff0d7c05-a443-45a7-a998-6bb9313529a5","order_by":10,"name":"Lining Sun","email":"","orcid":"","institution":"Suzhou University, China","correspondingAuthor":false,"prefix":"","firstName":"Lining","middleName":"","lastName":"Sun","suffix":""}],"badges":[],"createdAt":"2024-05-27 08:50:53","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4483564/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4483564/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":58315965,"identity":"9d6298ad-fdb4-46bd-8fb6-1e7ac492b721","added_by":"auto","created_at":"2024-06-13 21:00:22","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":137717,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSchematics of this proposed 3-axial tactile sensor for GEMIS.\u003c/strong\u003e(a) A multi-DOF manipulator passes through endoscopy with sensorized forceps sensing the 3-axial forces while manipulating. (b) The tactile sensor is integrated into the lower jaw of the GEMIS forceps and the Exploded view of the 3-axial tactile sensor. (c) Top view and side view of the 3-axial tactile sensor. (d) Sensing mechanism for normal force and shear force.\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-4483564/v1/45f5bd79065f2f986ea2c585.jpeg"},{"id":58314935,"identity":"f2f9c75b-7b83-46c2-9513-c598ae98dda0","added_by":"auto","created_at":"2024-06-13 20:52:22","extension":"jpeg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":176442,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFabrication of the sensor and assembly process of the sensorized forceps.\u003c/strong\u003e (a) Fabrication of the sensor chip. (b) The fabricated sensor chip on the index finger. (c) SEM picture of the sensor chip. (d) Fabrication of the elastic layer. (e) i: A sensor chip fixed on the FPCB and a case; ii: Integrate the sensor chip and the case together; iii: Integrate with the lower jaw; iv: The sensorized forceps. (f) The forceps are mounted on a flexible surgical arm with a diameter of 3.5mm, passing through the 3.8mm work channel of the gastrointestinal endoscope.\u003c/p\u003e","description":"","filename":"floatimage2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-4483564/v1/ee3cd513e91e8f977a816d99.jpeg"},{"id":58314933,"identity":"99b78a4c-e2aa-4a44-9050-f738a4dc3d95","added_by":"auto","created_at":"2024-06-13 20:52:22","extension":"jpeg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":250360,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eCharacterization and calibration of the sensorized forceps.\u003c/strong\u003e (a) Entire view of the experimental setup for the calibration of the developed forceps. (b) Repeated curves of the cantilevers as a function of normal force and lateral force. (c) Each cantilever’s voltages versus external forces along Z axis results with a 95% confidence interval evaluated over 6 attempts. (d) Voltage data measured by the 3-axial tactile sensor at the developed forceps with respect to the external 3-axial forces measured by the reference sensor. (e) Calibrated 3-axial force of the jaw with respect to the reference 3-axial forces.\u003c/p\u003e","description":"","filename":"floatimage3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-4483564/v1/1783c758da49d0eaa9cd60a5.jpeg"},{"id":58314936,"identity":"86bf8b8b-6516-4063-aedd-47f857616906","added_by":"auto","created_at":"2024-06-13 20:52:22","extension":"jpeg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":345934,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eResponses of the sensorized forceps while grasping simulated tumor tissue (PDMS).\u003c/strong\u003e(a) Grasping three times. (b) Grasping and pulling processes along X direction. (c) Grasping and pulling processes along Y direction.\u003c/p\u003e","description":"","filename":"floatimage4.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-4483564/v1/464ea7902a8eb551f2d7259d.jpeg"},{"id":58315966,"identity":"62a3308b-1456-4226-824a-79f7cc6a7523","added_by":"auto","created_at":"2024-06-13 21:00:22","extension":"jpeg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":162816,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eResponses of the sensorized forceps while grasping simulated gastric mucosa (TPR).\u003c/strong\u003e(a) No grasping (b) Grasping. (c) Grasping and pulling processes along X direction. (d) Grasping and keep pulling. (e) Keep pulling and the tissue slipped out of the forceps.\u003c/p\u003e","description":"","filename":"floatimage5.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-4483564/v1/ca98261882761e5fe0d60abc.jpeg"},{"id":58314937,"identity":"bdeb74aa-eeca-4199-bf4f-f2c0009ad047","added_by":"auto","created_at":"2024-06-13 20:52:22","extension":"jpeg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":213245,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eExperimental validation of the sensorized forceps while grasping circumcised gastric mucosa. \u003c/strong\u003e(a) Overview of the developed forceps and the circumcised gastric mucosa within the gastric body, alongside the complete experimental process. (b) Voltage response from the four cantilevers recorded throughout the experiment. (c) Calibrated force response from the forceps captured during the experiment.\u003c/p\u003e","description":"","filename":"floatimage6.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-4483564/v1/fb67bc05ca1137d0ca1002a0.jpeg"},{"id":58316545,"identity":"887c1a3f-8566-415d-beaa-f382c7815617","added_by":"auto","created_at":"2024-06-13 21:08:23","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2004727,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4483564/v1/30fc6264-8449-499d-8387-587ffe4eeda4.pdf"},{"id":58314932,"identity":"7a0b453e-3c16-42de-b375-ffbf7e62db80","added_by":"auto","created_at":"2024-06-13 20:52:22","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":766110,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cbr\u003e\u003c/p\u003e","description":"","filename":"MXNSupportinginformationv0527.docx","url":"https://assets-eu.researchsquare.com/files/rs-4483564/v1/c223706ecd6bfe5d567f4ca1.docx"},{"id":58314940,"identity":"02ab1646-5b47-4502-9348-18e5e5a2928a","added_by":"auto","created_at":"2024-06-13 20:52:23","extension":"mov","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":54271366,"visible":true,"origin":"","legend":"\u003cp\u003eGrasping and Pulling the Simulated Tumor Tissue in X- and Y- Direction\u003c/p\u003e","description":"","filename":"MXN1.mov","url":"https://assets-eu.researchsquare.com/files/rs-4483564/v1/764f115065ca77bfaf1e4f1c.mov"},{"id":58314941,"identity":"4f6056b3-0fb6-4015-9d2e-69f7005be4e1","added_by":"auto","created_at":"2024-06-13 20:52:23","extension":"mov","order_by":3,"title":"","display":"","copyAsset":false,"role":"supplement","size":38585698,"visible":true,"origin":"","legend":"\u003cp\u003eGrasping and Pulling the Mimic Gastric Mucosa in X-Direction\u003c/p\u003e","description":"","filename":"MXN2.mov","url":"https://assets-eu.researchsquare.com/files/rs-4483564/v1/5669f11a7e1ce76f6a778bb8.mov"}],"financialInterests":"(Not answered)","formattedTitle":"A Piezoresistive-based 3-axial MEMS Tactile Sensor and Its Integrated Surgical Forceps for Gastrointestinal Endoscopic Minimally Invasive Surgery","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eAdvancements in medical technology have positioned robotic-assisted surgery (RAS) as a crucial sector that can comprehensively enhance surgical precision and efficiency\u003csup\u003e1\u0026ndash;6\u003c/sup\u003e. Recently, RAS has been evolving towards Single Port Laparoscopy\u003csup\u003e7\u003c/sup\u003e (SPL) and Natural Orifice Transluminal Endoscopic Surgery\u003csup\u003e8,9\u003c/sup\u003e (NOTES), aiming to lessen patient invasiveness, hasten recovery, and reduce complication risks\u003csup\u003e7\u0026ndash;9\u003c/sup\u003e. SPL, conducted through a single, small incision, significantly reduces the number and size of surgical incisions, thereby easing patient recovery and improving cosmetic results post-operation\u003csup\u003e10\u003c/sup\u003e. NOTES introduces instruments via natural orifices, avoiding abdominal cuts, leading to nearly invisible scars, quicker recovery, and lower infection risks\u003csup\u003e11\u003c/sup\u003e. These designs include highly flexible, multi degree of freedom (DOF), and miniaturized manipulators for skilled operations\u003csup\u003e1\u003c/sup\u003e. In NOTES, a prevalent practice involves the removal of early-stage neoplastic tissues via gastroscopy, including techniques like Endoscopic Submucosal Dissection (ESD). This method employs flexible endoscopes, either single- or dual-channel, to navigate the complex and winding paths of the gastrointestinal tract for surgical interventions. Figure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea illustrates the developed surgical instrument\u003csup\u003e12,13\u003c/sup\u003e, equipped with a multi-DOF manipulator designed for gastrointestinal endoscopic procedures. This manipulator is adept at manipulating tissues through an endoscope's 3.8 mm work channel and features an external diameter of less than 3.5 mm\u003csup\u003e12\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eHowever, the lack of force sensing in surgical leading to heavy reliance on visual observation and experience\u003csup\u003e4,14\u0026ndash;17\u003c/sup\u003e. This gap can cause excessive force application, risking damage to sensitive tissues and increasing surgical errors; therefore, it is crucial to introduce instruments with force sensing capabilities to improve surgical accuracy and safety\u003csup\u003e1,5\u003c/sup\u003e. Additionally, integrating force sensing is vital for preventing tissue slippage, thereby boosting procedural efficiency\u003csup\u003e18\u0026ndash;20\u003c/sup\u003e. To address this issue, force/tactile sensors and actuators have been integrated as essential components of RAS systems. In some recently studies, sensors are commonly integrated into the joint drive units of surgical instruments to indirectly estimate interaction forces by analyzing the responses of the drivers\u003csup\u003e14,21\u003c/sup\u003e. Nonetheless, measurement accuracy is affected by mechanical factors like coupling, friction, and gravity\u003csup\u003e2,22\u0026ndash;25\u003c/sup\u003e. To counteract this, direct sensor placement has been explored at critical points such as the instrument's abdominal axis, wrist joints, and the tip's direct contact areas with tissue, enhancing force measurement precision as proximity to tissue increases\u003csup\u003e2,6,23,25\u003c/sup\u003e. This shift underlines the growing focus on embedding tactile sensors directly onto minimally invasive surgical (MIS) instruments' tips and joints for more accurate force detection\u003csup\u003e23,25\u003c/sup\u003e, utilizing electrical piezoresistive\u003csup\u003e2\u0026ndash;4,6,17,26\u0026ndash;28\u003c/sup\u003e, piezoelectric\u003csup\u003e29,30\u003c/sup\u003e, capacitive\u003csup\u003e23,25,31\u0026ndash;34\u003c/sup\u003e and optical methods\u003csup\u003e35\u0026ndash;40\u003c/sup\u003e. Kim et al.\u003csup\u003e23,25\u003c/sup\u003e and Lee et al.\u003csup\u003e31\u003c/sup\u003e developed capacitive-based force sensor, integrating them into surgical instruments with diameters ranging from 8 mm to 10 mm. Kuwana et al.\u003csup\u003e41\u003c/sup\u003e devised a piezoresistive MEMS force sensor and incorporated it into a MIS surgical instrument with an outer diameter of 12 mm. Although these solutions have addressed the lack of force sensing in surgical instruments, the instruments themselves remain relatively large. This highlights an ongoing need for further miniaturization of force sensing technologies. Researchers conducted by Yurkewich et al.\u003csup\u003e42\u003c/sup\u003e, Li et al.\u003csup\u003e43\u003c/sup\u003e, and Suzuki et al.\u003csup\u003e44\u003c/sup\u003e have employed Fiber Bragg Gratings (FBGs) technology, which measures strain by detecting shifts in the wavelength of light reflected from periodic gratings in an optical fiber. They integrated it at various locations on surgical instruments, such as the shaft and wrist, to enhance force sensing capabilities. However, optical fibers cannot be routed within small bending radii. Additionally, the use of small and complex components in SPL and NOTES could increase manufacturing and assembly costs. These factors highlight the challenges facing fiber-based sensor solutions.\u003c/p\u003e \u003cp\u003eTo overcome these limitations, this work introduces a miniature piezoresistive-based MEMS 3-axial tactile sensor, offering a solution for force sensing in gastrointestinal endoscopic minimally invasive surgery (GEMIS) that integrates compact sensors with high-integration and high-precision force sensing. This compact sensor, featuring a piezoresistive sensor chip equipped with four cantilever structures, encased in a protective housing with a central aperture. An elastic layer is employed to transmit external forces, and a flexible printed circuit board (FPCB) facilitates chip bonding and signal transmission. Utilizing MEMS fabrication techniques, a miniature piezoresistive chip was prepared. The fully encapsulated sensor can be seamlessly and extremely simple integrated into surgical forceps with an external diameter of 3.5 mm as illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea and \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb. The sensorized forceps underwent analysis and calibration for the sensing characteristics and 3-axial forces dynamics. Repeatability tests demonstrated the sensor's exceptional stability. Calibration revealed its high resolution and minimal mean relative error, highlighting significant advantages. The efficacy of the sensorized forceps is evaluated by testing their ability to grasp and pull tissue-mimetic materials, assessing the accuracy and reliability of the forces applied. Experimental demonstration of ex-vivo porcine stomach was performed to validate the effectiveness of the proposed 3-axial sensorized forceps based on the piezoresistive MEMS tactile sensor.\u003c/p\u003e"},{"header":"2. Results and Discussion","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Design and working principle\u003c/h2\u003e \u003cp\u003eA prototype of the gastrointestinal endoscopic dissecting forceps\u003csup\u003e13\u003c/sup\u003e incorporating the 3-axial tactile sensor is depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea. To accommodate 3-axial force manipulations, the sensorized forceps integrate a tactile sensor within the lower jaw, as illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb. The jaw is specifically designed with a slot to securely fit the sensor. In the configuration of the tactile sensor, as shown in the Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec, it mainly composed of four components: an elastic force transfer layer, a stainless-steel case, a FPCB, and a piezoresistive sensor chip. The piezoresistive sensor chip, measuring 2.0 mm by 2.0 mm with a thickness of 0.3 mm, is designed to be sufficiently small for integration into the jaw. In this sensor, it is bonded and wired to the FPCB and leads the analog signal through the FPCB\u0026rsquo;s gold wire. The case with a size of 2.7 mm \u0026times; 4.5 mm is fixed with the FPCB, which has an inner cavity that completely covers the chip. Thus, it can protect the bonding gold wires between the chip and FPCB. The elastic force transfer layer is attached to the surface of the case, while the column in the transfer layer is attached to the chip and in contact with the four cantilevers. Hence, external forces are allowed to make indirect contact with the sensitive cantilevers through the middle hole of the case. This rigid-flexible coupling structure enhances the sensitivity and accuracy of force signal transmission, while its integrated and modular architecture facilitates mass production and ensures robust environmental adaptability. In this design, the FPCB with dimensions of 1.8 m in length, 1 mm in width, and 0.1 mm in thickness, has a significant advantage as the gold flat cable can bypass the tail of the jaw and travel through the entire flexible manipulator via the inner cavity. Accordingly, it can move freely in its inner cavity when the manipulator is operated.\u003c/p\u003e \u003cp\u003eThe piezoresistive tactile sensor, which detects forces based on the resistance change of piezoresistors due to its deformation under external forces. In this proposed sensor, the elastic layer functions as a cover that protects the cantilevers and interacts with the target tissue. The top view of the sensor chip is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ed, two rectangular piezoresistors positioned in the vertical direction (denoted as R2 and R4) and two more positioned in the horizontal direction (denoted as R1 and R3) (Figure \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003ea, Supporting information). Each piezoresistor consists of two rectangular piezoresistors (red block), with the size of 5 \u0026micro;m \u0026times; 60 \u0026micro;m, and the resistances are concentrated in the stress concentration area (Figure \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003eb, Supporting information). The external forces exerted on the elastic layer are conveyed to the cantilevers via the intermediary column. In this arrangement of piezoresistive cantilevers and columns, the responses of each piezoresistive element generate distinct outputs. These allow for the independent characterization of stresses associated with external forces, specifically normal and shear forces. As depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ee, under normal force, identical compressive deformations at each of the four cantilevers yield similar strain-induced changes in resistances of the four piezoresistive elements. Uniaxial shear force applied along the direction of X-axis leads to strain difference of two coaxial cantilevers, i.e., a correspondingly large increase in resistance of R3 and a corresponding small increase in resistance of R1, while with negligible strain difference of the other two cantilevers along the Y-axis of R2 and R4. When the forceps grasp an object, the upper and lower jaws close, and the grasped object applies a downward force on the elastic layer, resulting in the compression of the tactile sensor. Subsequently, the cantilevers of the sensor deform, leading to changes in resistances. The signal wires are routed from the back of the sensor and extend through the shaft of the forceps to the end, as illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea and \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2. Fabrication and assembly process\u003c/h2\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea illustrates the detailed fabrication process of the sensor chip. The procedure commences with an n-type, (100)-oriented silicon-on-insulator (SOI) wafer, utilized as the initial substrate, featuring a device layer thickness of 5 \u0026micro;m. Initially, SiO\u003csub\u003e2\u003c/sub\u003e layers were thermally grown on both sides of the wafer. Subsequent steps included the photolithography process on the wafer's front side to delineate the piezoresistors. This was followed by the implantation of boron ions at a dosage of 5 \u0026times; 10\u003csup\u003e14\u003c/sup\u003e cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e. Rapid thermal annealing (RTA) was then applied to activate the dopants, thereby forming the piezoresistors. A subsequent boron ion implantation was carried out with a dosage of 2 \u0026times; 10\u003csup\u003e15\u003c/sup\u003e cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e, followed by an RTA step to establish ohmic contacts. Aluminum was then sputtered and patterned to a thickness of 700 nm, facilitating the metallization required for interconnections with the piezoresistors. Precise regulation of the diffusion temperature and duration enabled consistent and efficient doping, achieving less than 2% variability in the mean value across four cantilevers within a single batch (Figure \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003ec, Supporting Information). Plasma Enhanced Chemical Vapor Deposition (PECVD) was employed to deposit a 1 \u0026micro;m layer of silicon nitride (SiN\u003csub\u003ex\u003c/sub\u003e), which served to offset the compressive stress within the SiO\u003csub\u003e2\u003c/sub\u003e layer and protect the surface electrodes. The fabrication continued with the opening of contact pads and the patterning and etching of cantilevers. Backside deep reactive ion etching (DRIE) was conducted to release the cantilever structure down to the buried oxide (BOX) layer. Subsequently, the buried SiO\u003csub\u003e2\u003c/sub\u003e layer was removed via reactive ion etching. The final sensor chip, measuring 2.0 \u0026times; 2.0 \u0026times; 0.3 mm\u003csup\u003e3\u003c/sup\u003e, is depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb, positioned on an index finger. The cantilever structures are distinctly visible in the scanning electron microscope (SEM) image shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec.\u003c/p\u003e \u003cp\u003eIn addition to the piezoresistive sensor chip, the elastic force transfer layer is also crucial, since it can transmit external excitation to the sensitive cantilevers, also serves as an encapsulation. A stainless-steel mold shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ed and Figure S2 (Supporting information) is needed to form the column structure, thus it can pass through the case\u0026rsquo;s hole (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec) and contact with the sensor\u0026rsquo;s cantilevers. The height of the column becomes the focus in order to ensure that the column and the cantilevers can also be in proper contact in load free. While the height of the column is determined by the following factors: the height of the sensor chip (300 \u0026micro;m), the height of the case (500 \u0026micro;m). Hence, the height of the column is determined as 200 \u0026micro;m.\u003c/p\u003e \u003cp\u003ePouring the Polydimethylsiloxane (PDMS, Sylgard184, Dow Corning Corp) with a mixture ratio of 10:1 (PDMS polymer base: polymerization agent) into the machined mold. Sort it in a vacuum box for 10 minutes to eliminate bubbles, subsequently heat 15 minutes at 100 ℃ in oven. Pay special attention to pressing a glass plate on the surface of the PDMS so that it can ensure a flat surface. After that, lift out to obtain the elastic layer, resulting in a Young\u0026rsquo;s modulus of approximately 2.61 MPa of the transfer layer\u003csup\u003e6\u003c/sup\u003e (Table \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e, Supporting information). Finally, the final elastic layer with dimensions of 4.5 mm \u0026times; 2.7 mm and a central column of 1.6 mm \u0026times; 0.2 mm is produced (Figure S2, Supporting information).\u003c/p\u003e \u003cp\u003eIn adherence to the outlined specifications, the sensor-integrated jaw has been meticulously crafted. The main body and housing are constructed from 304 stainless steel, endowed with a Young's modulus of 200 GPa, ensuring robustness and durability. The gripping section of the jaw body spans a length of 8.0 mm, and upon closure, the total external diameter of the conjoined jaws remains below the 3.5 mm threshold (Figure S3, Supporting information). This compact design facilitates seamless insertion through the endoscope's 3.8 mm diameter working channel. Coupling this sensor-equipped jaw with an external 3.5 mm flexible manipulator enables precise navigation and operation under endoscopic control.\u003c/p\u003e \u003cp\u003eThe piezoresistive sensor chip, is meticulously bonded to the FPCB with a height of 0.1 mm. A stainless-steel sheet, also 0.1 mm thick, reinforces the sensor's stationary region to prevent deformation and maintain sensor integrity. Figure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ee (i) shows the sensor fixed on the FPCB and a case. Place the case over the sensor chip while making sure that the sensor's sensitive unit is fully transparent to the case\u0026rsquo;s hole, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ee (ii). The encasing measures 2.7 \u0026times; 4.5 \u0026times; 0.6 mm\u003csup\u003e3\u003c/sup\u003e, tailored to slot into the lower jaw with precision. Once inserted, the tactile sensor is anchored in place using silicone gel, ensuring a secure and stable assembly, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ee (iii). Finally, the upper and lower jaw are connected to the flexible manipulator using a hinge pin, shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ee (iv). This methodical assembly ensures that the sensorized forceps are equipped with a 3-axial force sensing capability, primed for complex surgical procedures.\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\u003eComparison of different force perception methods in MIS\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\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 \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStudy\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMethod and location\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eInstrument\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eD (mm)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eKim et al.\u003c/b\u003e\u003csup\u003e23,25\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCapacitive-based transducers integrated into the grasper\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eS-Surge Surgical Robot\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eLee et al.\u003c/b\u003e\u003csup\u003e31\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCapacitive-based sensor integrated into wrist and instrument base\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eRAVEN-II\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eKuwana et al.\u003c/b\u003e\u003csup\u003e41\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePiezoresistive-based sensor integrated into grasper\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMIS laparoscopic grasper\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eYurkewich et al.\u003c/b\u003e\u003csup\u003e42\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFBGs-based sensor integrated into distal shaft and gripper\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMIS arthroscopic grasper\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4.57\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eLi et al.\u003c/b\u003e\u003csup\u003e43\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFBGs-based sensor integrated into articulated wrist\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePalpation probe\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSuzuki et al.\u003c/b\u003e\u003csup\u003e44\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFBGs-based sensor near the tip of forceps\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eBilateral micro-operation system\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eThis work\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePiezoresistive-based sensor integrated into the forceps\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eGEMIS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3.5\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\u003eFigure \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ef illustrates a gastrointestinal endoscopic device featuring two work channels: a 2.7 mm channel for an electric knife (dual knife) and a 3.8 mm channel for a flexible manipulator, along with a light source and lens. During procedures, the dual knife and flexible manipulator are inserted through these channels to the target area to perform electro-dissection (electro-coagulation) and grasping tasks. The light source illuminates the confined surgical field, and the lens provides visual feedback. The sensorized forceps, integrated into the flexible manipulator's tip, facilitate 5-DOF movements including grasping, pitching, yawing, rolling, and advancing\u003csup\u003e12,13\u003c/sup\u003e. Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e compares this sensor's integrated instruments with previous studies, clearly demonstrating that the surgical digestive endoscopy forceps integrated with this sensor have the smallest external diameter, measuring only 3.5mm.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3. Force sensing characterization and calibration\u003c/h2\u003e \u003cp\u003eUpon the successful fabrication of the sensor-integrated forceps, a calibration experimental setup was established, as depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea. A commercial 6-axis force/torque sensor (Nano 17, ATI), mounted on a 3-DOF linear stage, served as the reference for measurements. The reference sensor was connected to an amplifier and a data acquisition system (NI-USB 6210, DAQ). Analog signals from the sensor were conditioned by electrical circuitry, where they were filtered and amplified before digitization by the DAQ and subsequent transmission to the computer. The sensor's electrical circuit employs a wheatstone bridge with three fixed resistors, each matched to the piezoresistor's initial resistance (Figure S4, Supporting information). External forces alter the piezoresistor's resistance, unbalancing the bridge. This imbalance induces a voltage change, which is then amplified by AD620. An AD705 serves as a buffer to the amplifier, stabilizing the output voltage at 2V when the bridge is balanced. The circuit's final output is directed to the DAQ (NI-USB 6210), and recorder through the data acquisition procedure (Figure S5, Supporting information). This setup allows for the capture of voltage signals from the four piezoresistors, enabling the computation of resistance changes and corresponding voltage fluctuations in each cantilever. In the front and top view of the calibration setup, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea, the 3-DOF stage exerts three orthogonal forces \u003cem\u003eF\u003c/em\u003e\u003csub\u003e\u003cem\u003eX\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003eF\u003c/em\u003e\u003csub\u003e\u003cem\u003eY\u003c/em\u003e\u003c/sub\u003e, and \u003cem\u003eF\u003c/em\u003e\u003csub\u003e\u003cem\u003eZ\u003c/em\u003e\u003c/sub\u003e onto the lower jaw of the forceps via its triaxial motion capabilities through one 3D printing jig. During the experiments, the measured voltage data and the reference data were recorded simultaneously.\u003c/p\u003e \u003cp\u003eTo evaluate the performance of the tactile sensor, normal force and shear force testing including the loading and unloading process were conducted. During the process, the experiments were repeated about 90 times along the Z axis. Figure S6 (Supporting information) shows the four cantilevers raw data without filter which has affirmed the sensor\u0026rsquo;s outstanding repeatability. Applying the Kalman filter method to the raw voltage data results in a smoother curve (Figure S7, Supporting information). Figure\u0026nbsp;3b1 shows six repeated curves of the cantilevers as a function of normal force from 0 to 1.2 N, while Figs.\u0026nbsp;3b2 and 3b3 display three repeated curves of the four cantilevers as a function of lateral force along the X and Y axes from \u0026minus;\u0026thinsp;0.6 to 0.6 N, respectively. To best meet the design requirements of surgical instruments, efforts have been made to achieve a grasping force of 0.77 N and a traction force of 0.71 N\u003csup\u003e12\u003c/sup\u003e. While there is potential for further increasing the calibrated normal force, a normal force of 1.2 N is sufficient to prevent the lower jaw from slipping when the shear force is increased to 0.6 N, thus ensuring effective calibration. Although the 0.6 N shear force is slightly below the target value, the data still meet the requirements for procedures such as Endoscopic Submucosal Dissection (ESD). The voltages versus normal force relationships of four cantilevers are presented in Fig.\u0026nbsp;3c1, c2, c3 and c4 with a 95% confidence interval. The series of repeated tests conducted has affirmed the sensor's outstanding repeatability, evidenced by the majority of voltage readings aligning within the prescribed confidence intervals. This consistency furnishes credible data underpinning the sensor's calibration process.\u003c/p\u003e \u003cp\u003eTo measure the quantitative values of forces, bridging the gap between the voltage variances of four cantilevers and the 3-axial forces based on proper calibration is essential. Figure\u0026nbsp;3d1, d2 and d3 shows the tendencies of the four cantilevers' voltage data of the forceps based on the reference data. In the graphs, the data points for voltages correspond to the mean of repeated measurements, ranging from 0 to 1.2 N along the Z-axis and from \u0026minus;\u0026thinsp;0.6 to 0.6 N along the X and Y axes. As shown in Fig.\u0026nbsp;3d1, the four voltages are changed in the same direction. The voltages increase by the external force from 0 to 1.2 N. At the same time, the voltage data for the four cantilevers exhibit almost uniform variations. Externally applied forces in the X-direction induce significant voltage changes in cantilevers 2 (V\u003csub\u003e2\u003c/sub\u003e) and 4 (V\u003csub\u003e4\u003c/sub\u003e), which are aligned with the X-axis, whereas cantilevers 1 (V\u003csub\u003e1\u003c/sub\u003e) and 3 (V\u003csub\u003e3\u003c/sub\u003e), oriented along the Y-axis, exhibit minimal voltage variations, as shown in Fig.\u0026nbsp;3d2. The trends in voltage shifts for cantilevers 2 and 4 are entirely antithetical. The modest voltage fluctuations observed in cantilevers 1 and 3 are primarily attributable to assembly inaccuracies. Conversely, the shear forces applied in the Y-direction yield an inverse response, as shown in Fig.\u0026nbsp;3d3. As a result, the tendencies of the measured voltages with respect to the external 3-axial forces are consistent with the explanation provided of the working principle.\u003c/p\u003e \u003cp\u003eFor the purpose of calibrating the 3-axial forces from the voltage data after filtering, it was imperative to establish a calibration matrix. Given the observed good linearity of voltage responses of the four cantilevers under the application of triaxial forces, this matrix was deduced utilizing the linear least squares method (see Text S1, Supporting information), which provides a correlation between the external 3-axial forces and the corresponding voltage readings. The calibration matrices \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(A\\)\u003c/span\u003e\u003c/span\u003e is calculated as:\u003cdiv id=\"Equ1\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ1\" name=\"EquationSource\"\u003e\n$$A= \\left[\\begin{array}{cc}\\begin{array}{cc}-0.1411\u0026amp; 0.48225\\\\ 0.25225\u0026amp; 1.01904\\\\ 0.33861\u0026amp; 1.28641\\end{array}\u0026amp; \\begin{array}{cc}-0.2460\u0026amp; 0.77293\\\\ 0.10931\u0026amp; -1.3922\\\\ -2.4574\u0026amp; 0.88168\\end{array}\\end{array}\\right]$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e1\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eThus, the 3-axial forces \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\left[\\begin{array}{ccc}{F}_{X}\u0026amp; {F}_{Y}\u0026amp; {F}_{Z}\\end{array}\\right]}^{T}\\)\u003c/span\u003e\u003c/span\u003e can be calculated through the equation: \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(A\u0026middot;{\\left[\\begin{array}{cc}\\begin{array}{cc}{V}_{1}\u0026amp; {V}_{2}\\end{array}\u0026amp; \\begin{array}{cc}{V}_{3}\u0026amp; {V}_{4}\\end{array}\\end{array}\\right]}^{T}\\)\u003c/span\u003e\u003c/span\u003e. In consequence, the calibrated 3-axial forces measured by the sensorized forceps with respect to the reference force can be seen in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ee, in which e1 for the Z-axis force, e2 for the X-axis force, and e3 for the Y-axis force. The experimental findings enabled the determination of the force resolution for the tactile sensor, which was established as 0.66 mN, 0.61 mN, and 0.28 mN for the respective axes. The mean relative error was calculated to be 1.15%, 2.43%, and 1.18% of the full-scale output (FSO) force ranges, corresponding to each axis. The sensor's performance are listed in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. For detailed calculation description, see text S1, S2, and S3 (Supporting information).\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\u003ePerformance of the developed 3-axial tactile sensor of the sensorized forceps\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\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 \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eQuantity\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003eValue\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eUnit\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eX-axis\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eY-axis\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eZ-axis\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eForce range\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eN\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eForce resolution\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.66\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.61\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003emN\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMean relative error\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e% of FSO\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"5\" nameend=\"c5\" namest=\"c1\"\u003e \u003cp\u003e*FSO: Full scale output force range\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=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.4. Experimental validations of sensorized forceps\u003c/h2\u003e \u003cp\u003eIn RAS, the use of forceps can be categorized into two main scenarios: grasping and pulling. Grasping primarily involves the application of normal forces, whereas pulling mainly involves the application of shear forces. Two distinct types of materials are used to simulate two radically different tissues within the gastrointestinal tract. PDMS with a doping ratio of 30:1 (Young\u0026rsquo;s modulus of 0.86 MPa, Table \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e, in Supporting information) is used to simulate tumor tissues such as gastric adenocarcinoma or gastrointestinal stromal tumors, which are generally harder and have a different texture compared to the gastric mucosa. To simulate the conditions of gastric mucosa during gastrointestinal surgeries, thermoplastic rubber (TPR) is selected as the demonstration model for the integrated system verification.\u003c/p\u003e \u003cp\u003eInitially, the forceps perform three grasping actions on the simulated tumor tissue, followed by a pulling action along the X-axis. Subsequently, the forceps grasp the simulated tumor tissue and move it along the Y-axis direction, thereby evaluating the capability to detect forces in different directions. During this process, data collection occurs at a sampling frequency of 1000 Hz, and the obtained three-axis force values are presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e. It warrants emphasis that, as the forceps incrementally engage with the simulated tumor tissue, the concurrent generation of both shear and normal forces ensues, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea. The forceps also exhibit commendable responsiveness to pulling actions on tissues in both the X and Y directions. However, during the pulling of tissue in the Y direction, since the traction on the tissue does not occur purely along the Y-axis but is accompanied by a component in the X direction, there is also a significant response in \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({F}_{X}\\)\u003c/span\u003e\u003c/span\u003e with each action, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ec.\u003c/p\u003e \u003cp\u003eDue to the softer nature of simulated gastric mucosa (TPR), it is easier to discern the applied actions from its deformation during grasping and pulling. The grasping and pulling actions are illustrated from Fig.\u0026nbsp;5a1 to 5e1, with the force values response at various stages shown in Fig.\u0026nbsp;5a2 to 5e2. As the forceps grasp the simulated gastric mucosa, the three-axis forces begin to be displayed in Fig.\u0026nbsp;5b2, with \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({F}_{Z}\\)\u003c/span\u003e\u003c/span\u003e showing the most significant increase. Upon pulling in the X direction, the \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({F}_{X}\\)\u003c/span\u003e\u003c/span\u003e value increases; when the pulling stops, the \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({F}_{X}\\)\u003c/span\u003e\u003c/span\u003e value decreases. As pulling continues, \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({F}_{X}\\)\u003c/span\u003e\u003c/span\u003e increases further. During the pulling process, the tissue begins to slip within the forceps, and the amount of simulated mucosa gripped by the forceps continuously decreases, as shown in Fig.\u0026nbsp;5d2. When a sudden drop in \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({F}_{X}\\)\u003c/span\u003e\u003c/span\u003e occurs in Fig.\u0026nbsp;5e2, it indicates that the simulated mucosa has lost effective grip within the forceps and needs to be regripped.\u003c/p\u003e \u003cp\u003eAlthough TPR is sufficiently soft to simulate gastric mucosa, it still differs significantly from actual gastric mucosa. Consequently, we prepared a fresh porcine stomach and randomly selected an area on the gastric body for marking and circumcising. We then used the sensorized forceps to grasp and pull the circumcised gastric mucosa, assessing the effectiveness of these forceps in a real porcine stomach test. The ex vivo experiments on a porcine stomach is depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ea. During the experiment, an assistant positioned the flexible arm at an appropriate location on the stomach body, while the operator controlled the arm's movement and the forceps\u0026rsquo; opening and closing with their main hand to grasp and pull the pre-circumscribed lesion. The grasping and pulling actions are illustrated from ① to ④, with the voltage values and force values response at various stages shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eb and \u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ec. Throughout the grasping and pulling process, changes in three-dimensional forces occur, particularly at the initiation of grasping, the beginning of pulling, and when slippage occurs. The maximum grasping force during the process is approximately 0.17 N, which is significantly lower than the forces observed when grasping PDMS and TPR. Unlike grasping TPR, the value of \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({F}_{X}\\)\u003c/span\u003e\u003c/span\u003e inversely increases when grasping actual gastric mucosa, and the absolute value of \u003cem\u003eF\u003c/em\u003e\u003csub\u003e\u003cem\u003eX\u003c/em\u003e\u003c/sub\u003e decreases as pulling continues. This is primarily due to the irregular shape of the gastric mucosa. Compared to \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({F}_{X}\\)\u003c/span\u003e\u003c/span\u003e and \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({F}_{Z}\\)\u003c/span\u003e\u003c/span\u003e, the forces \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({F}_{Y}\\)\u003c/span\u003e\u003c/span\u003e is smaller. Feedback on the entire process of force changes is provided to the operator, who can then feel the progression of these changes and determine the actions of clamping and pulling.\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Conclusion","content":"\u003cp\u003eThis work introduces a compact piezoresistive MEMS 3-axial tactile sensor for GEMIS. This tactile sensor, characterized by its innovative design, incorporates a piezoresistive chip with four cantilever structures housed within a protective casing featuring a central aperture. An elastic force transfer layer is utilized for the transmission of external forces, while a FPCB ensures efficient chip bonding and signal transmission. The meticulous application of MEMS process flow techniques facilitated the creation of a miniature piezoresistive chip, measuring just 2.0 \u0026times; 2.0 \u0026times; 0.3 mm\u003csup\u003e3\u003c/sup\u003e. The fully encapsulated sensor, with overall dimensions of 4.5 \u0026times; 2.7 \u0026times; 0.6 mm\u003csup\u003e3\u003c/sup\u003e, demonstrates the feasibility of its integration into surgical forceps with an external diameter of 3.5 mm, offering a straightforward and seamless incorporation process.\u003c/p\u003e \u003cp\u003eThe study further delves into a comprehensive analysis and calibration of the sensorized forceps, focusing on their sensing characteristics and 3-axial force dynamics. Through repeated tests, the tactile sensor showcased exceptional stability, with calibration results revealing its superior resolution as high as 0.28 mN in \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({F}_{Z}\\)\u003c/span\u003e\u003c/span\u003e and minimal average relative error down to 1.18% of FSO. These findings underscore the sensor's significant advantages, particularly in terms of its performance and reliability.\u003c/p\u003e \u003cp\u003eMoreover, the practical application and effectiveness of the sensorized forceps were assessed through tests involving the manipulation of tissue-mimetic materials and ex vivo of porcine gastric. These tests, aimed at evaluating the accuracy and reliability of both grasping and pulling forces, demonstrated the sensor's potential in enhancing the precision and efficacy of surgical procedures. In future work, we will further focus on optimizing and minimizing the sensor design to enhance its versatility and broaden its potential applications in NOTES, especially the application in the DREAMS (Dual-arm Robotic Endoscopic Assistant for Minimally Invasive Surgery). Additionally, animal clinical trials will be conducted to assess the feasibility and effectiveness of the sensor in a clinical environment.\u003c/p\u003e"},{"header":"4. Experimental Section","content":"\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e4.1 Description of the amplifier circuit for analog signals\u003c/h2\u003e \u003cp\u003eFigure S4 illustrates the amplifier circuit employed for the sensor, with the detailed schematic of the individual circuit shown on the right. The circuit operates with a 5V power supply and incorporates three fixed resistors within the Wheatstone bridge, calibrated to match the resistance of the initial piezoresistor value. When subjected to external forces, the resistance of the piezoresistor changes, thereby disturbing the balance of the Wheatstone bridge. The resultant voltage output from the bridge is subsequently amplified by the AD620 operational amplifier, which has a gain factor of 19.93 and an RG resistance of 2611 Ω. To achieve an initial output voltage of 2 V in the balanced state, the AD705 is employed as a follower to the amplifier chip. The output of the circuit is then directed to the analog input of a data acquisition system (DAQ), specifically the NI-USB 6210. Consequently, voltage signals from the four piezoresistors are available, enabling the computation of resistance changes (ΔR) and voltage variations in each direction.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e4.2 Description of the signal acquisition system based on LabView\u003c/h2\u003e \u003cp\u003eTo ensure real-time and accurate voltage data acquisition from the sensorized forceps and the standard sensor, a real-time data acquisition and display interface was developed based on LabVIEW, as shown in Figure S5a. This interface allows for the real-time display of voltage changes in the force-sensing clamp due to the piezoresistive effect. The LabVIEW display interface juxtaposes the signal data from the sensorized forceps and the ATI Nano17, facilitating a more intuitive comparison of their signal responses. This not only enhances the display quality but also enables the synchronous acquisition of time-domain signals from both sensors. The detailed acquisition interface is shown in Figure S5b, where the upper section displays the force/torque information from the standard sensor, and the lower section shows the unfiltered voltage signals from the sensorized forceps.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e4.3 Preparation of gastric corpus mimic lesions\u003c/h2\u003e \u003cp\u003eFirst, rinse the inner and outer walls of the pig stomach with clean water and place the stomach into a stainless-steel tray. The bottom of the tray is equipped with the negative electrode plate required for the high-frequency electric knife. Use the coagulation function of the electric knife to mark the area around the gastric body before circumcision. After marking, use the electric knife to cut along the outer edge of the marks and continue cutting the mucosal tissue below the inner wall of the circumscribed area to complete the simulation of the lesion.\u003c/p\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eCompeting interests:\u003c/h2\u003e \u003cp\u003eThe authors declare no other competing interests.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eData and materials availability\u003c/strong\u003e \u003cp\u003eAll data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials. Additional data related to this paper may be requested from the authors.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eAuthor contributions\u003c/h2\u003e \u003cp\u003eC.H. conceived the tactile sensor idea and operation principle. C.H. and H. L. developed fabrication processes based on previous work. C. H. fabricated and characterized the devices and performed all data collection and analysis. C.H. prepared figures, drawings, and schematics. C.H. and B. L. took SEM pictures. H.L., together with C.H., H. G, and X. Y. performed experiments related to robotics. C.H. drafted the manuscript. All authors discussed the results and commented on the manuscript. H.L. and B. L. provided a critical revision of the article. C.H. and B. L. revised the manuscript. H.L. and L.S. provided critical feedback to the development of the sensing module concept, fabrication process and materials investigations, device characterization, data interpretation, and critical revision of the article.\u003c/p\u003e\u003ch2\u003eAcknowledgments\u003c/h2\u003e \u003cp\u003eThe work presented in this paper was a collaboration of all authors. This work was funded by the Natural Science Foundation of the Higher Education Institutions of Jiangsu Province, China (21KJA460006), the Natural Science Foundation of Jiangsu Province of China (BK20220490) and the National Natural Science Foundation of China (62203315).\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eDupont, P. E. \u003cem\u003eet al.\u003c/em\u003e A decade retrospective of medical robotics research from 2010 to 2020. 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IEEE Robotics and Automation Letters 3, 4281\u0026ndash;4288, doi:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1109/lra.2018.2864771\u003c/span\u003e\u003cspan address=\"10.1109/lra.2018.2864771\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2018).\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"microsystems-and-nanoengineering","isNatureJournal":false,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"micronano","sideBox":"Learn more about [Microsystems \u0026 Nanoengineering](http://www.nature.com/micronano/)","snPcode":"41378","submissionUrl":"https://mts-micronano.nature.com/","title":"Microsystems \u0026 Nanoengineering","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"ejp","reportingPortfolio":"Nature AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Robotic-assisted surgery, Gastrointestinal endoscopic surgery, Piezoresistive-based tactile sensor, MEMS, Force sensing","lastPublishedDoi":"10.21203/rs.3.rs-4483564/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4483564/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eIn robotic-assisted surgery (RAS), traditional surgical instruments without sentient capability cannot perceive accurate operational forces during the task, and such drawbacks can be largely intensified when conducting sophisticated tasks using flexible and slender arms with small end-effectors, e.g., in gastrointestinal endoscopic surgery (GES). In this work, we propose a micro-electro-mechanical systems (MEMS) piezoresistive 3-axial tactile sensor for GES forceps, which can intuitively provide surgeons with online force feedback during robotic surgery. The fabrication process of MEMS enables the sensor chips to possess dimensions of miniaturization. The fully encapsulated tactile sensors can be effortlessly integrated into miniature GES forceps, which feature a slender diameter of just 3.5 mm and undergo meticulous calibration procedures least squares method. In experiments, the sensor's capability to accurately measure directional forces up to 1.2 N in Z axis was validated, demonstrating an average relative error of only 1.18% compared to the full-scale output. The results indicate that this tactile sensor can provide effective 3-axial force sensing during surgical operations, such as grasping and pulling, and in ex-vivo testing of the porcine stomach. Its characteristics of compact size, high precision, and integrability establish solid foundations for clinical application in the operating theatre.\u003c/p\u003e","manuscriptTitle":"A Piezoresistive-based 3-axial MEMS Tactile Sensor and Its Integrated Surgical Forceps for Gastrointestinal Endoscopic Minimally Invasive Surgery","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-06-13 20:52:17","doi":"10.21203/rs.3.rs-4483564/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"revise","date":"2024-06-14T00:45:25+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"This content is not available.","date":"2024-06-09T03:12:05+00:00","index":2,"fulltext":"This content is not available."},{"type":"editorInvitedReview","content":"This content is not available.","date":"2024-06-04T07:24:31+00:00","index":1,"fulltext":"This content is not available."},{"type":"reviewerAgreed","content":"This content is not available.","date":"2024-06-02T10:59:00+00:00","index":2,"fulltext":"This content is not available."},{"type":"reviewerAgreed","content":"This content is not available.","date":"2024-05-31T02:51:23+00:00","index":1,"fulltext":"This content is not available."},{"type":"reviewersInvited","content":"","date":"2024-05-30T02:31:05+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-05-28T00:52:06+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-05-27T08:48:58+00:00","index":"","fulltext":""},{"type":"submitted","content":"Microsystems \u0026 Nanoengineering","date":"2024-05-27T08:48:57+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"microsystems-and-nanoengineering","isNatureJournal":false,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"micronano","sideBox":"Learn more about [Microsystems \u0026 Nanoengineering](http://www.nature.com/micronano/)","snPcode":"41378","submissionUrl":"https://mts-micronano.nature.com/","title":"Microsystems \u0026 Nanoengineering","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"ejp","reportingPortfolio":"Nature AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"b4a63b53-31d7-4255-9244-dd80650d1153","owner":[],"postedDate":"June 13th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[{"id":32582462,"name":"Physical sciences/Engineering/Electrical and electronic engineering"},{"id":32582463,"name":"Physical sciences/Nanoscience and technology/Nanoscale devices/Sensors"},{"id":32582464,"name":"Physical sciences/Nanoscience and technology/Other nanotechnology/Environmental, health and safety issues"}],"tags":[],"updatedAt":"2024-07-22T01:35:22+00:00","versionOfRecord":[],"versionCreatedAt":"2024-06-13 20:52:17","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4483564","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4483564","identity":"rs-4483564","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}