Wall-climbing microbots with ultrafast de-adhesion

Wall-climbing microbots with ultrafast de-adhesion | 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 Wall-climbing microbots with ultrafast de-adhesion Mingjing Qi, Xiangyu Yang, Jinzhe Peng, Wei Shen, Jingyu Che, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6083110/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Adhesion technologies enable robots to perform specialized tasks such as climbing and grasping, making them valuable for industrial applications. Electroadhesion (EA) stands out for its wide applicability, simple control, and low power consumption among various adhesion methods. However, its practical use is limited by the slow de-adhesion speed. In this study, we propose a novel method by introducing a self-excited pulse module into the driving circuit of EA pads. During the de-adhesion process, the residual charges induce self-excited vibrations of the cantilever beam within the module, generating an external pulsed electric field that matches the EA pads. This external field neutralizes the residual electric field, enabling ultrafast release. The proposed method elevates the release speed of EA pads by more than 90 times and reduces the adhesion force decay after repeated use from 56–11%. We developed an ultrafast wall-climbing microbot based on this method, achieving a climbing speed of 4.44 cm/s (with a step frequency of 2.2Hz), which is 5.6 to 25 times faster than the robots using traditional release methods. Furthermore, we developed the first untethered electroadhesive microbot by integrating a high-voltage power system. Physical sciences/Engineering/Electrical and electronic engineering Physical sciences/Engineering/Mechanical engineering Figures Figure 1 Figure 2 Figure 3 Figure 4 INTRODUCTION Climbing represents a critical survival skill for many small animals in nature, such as geckos, providing significant advantages in predation, evasion, and shelter acquisition through rapid climbing enabled by adhesion mechanisms. Similarly, specialized robots 1–4 often require adhesion and climbing capabilities to execute tasks such as exploration and transportation 5–7 . However, existing adhesion techniques face several limitations 8 . For instance, vacuum adhesion 9,10 demands smooth, non-porous surfaces; magnetic adhesion is confined to ferromagnetic materials; and bionic adhesion often exhibits low payload capacity and is highly sensitive to surface conditions, such as dust. Electroadhesion (EA) presents a promising alternative, which can generate adhesion forces on a wide range of surfaces 11 . This method provides controllable adhesion through electrical signals while maintaining minimal power consumption. However, existing EA technologies face significant challenges, particularly a slow de-adhesion speed caused by residual charges after power is turned off 12 . These residual charges create an electric field that sustains unwanted adhesion forces, and over time, the accumulation of such charges significantly diminishes adhesion efficacy 13 . To address the issue of slow release, early industrial EA grippers commonly relied on mechanical methods 14–16 , which pose risks of substrate damage 17 and bring a more than 50% decay 1 in EA force after several adhesion-release cycles. This paper presents a wall-climbing microbot (Fig. 1a) with ultrafast de-adhesion via a novel electrical control 18,19 method. This approach leverages a self-excited pulse module (Fig. 1b) integrated into the driving circuit of the EA pads. By effectively neutralizing the residual electric field 20 , the EA pads achieve release at a speed exceeding 90 times that of traditional methods (Fig. 1c). Moreover, the issue of residual charge accumulation is addressed, thereby reducing the adhesion force decay after repeated use from 56–11%. Finally, we developed the fastest legged wall-climbing microbot (Fig. 3 b, Supplementary Video S1) and the first untethered electroadhesive microbot (Fig. 1d, Supplementary Video S2). RESULTS Robot and self-excited pulse module design Figure 1a describes the general design and specific composition of the robot. The untethered wall-climbing robot primarily comprises electroadhesive (EA) pads, a drive and transmission system, a high-voltage power system, and self-excited pulse modules. During operation, the drive motors enable the middle and bilateral feet to alternate contact with the wall. At the same time, the high-voltage power system charges the EA pads to generate adhesion force. A servo functions as a double-throw switch, controlling the adhesion and release of EA pads on the middle and bilateral. Adhesion force is generated immediately upon contact of each set of pads with the wall and is rapidly removed just before the pads are released from the surface. Figure 1b shows the principle and configuration of the self-excited pulse module, an innovative electromechanical coupling device specifically designed to facilitate the rapid de-adhesion of EA pads. The module primarily comprises a switch, a conductive cantilever beam, and a pair of conductive parallel electrodes-one connected to the negative terminal of the power supply, while the other is maintained at a floating potential. The core component of this module is the conductive cantilever beam, which can be excited into vibration between two parallel electrodes due to residual charge within the EA pads and the substrate. This vibration generates a periodic pulse voltage signal, producing a periodic external electric field applied to the EA pads. This external field is tuned to match the adhesion parameters, effectively neutralizing the residual electric field and enabling rapid de-adhesion of the EA pads. Experimental results demonstrate that the self-excited pulse method can enhance the de-adhesion speed by more than 90-fold, as illustrated in Fig. 1c. Three lightweight materials—fabric, wood, and release paper (material parameters provided in Table S1 )—were selected as adhesion substrates. After these substrates were adhered to the robotic arm-operated EA pad, they were released using the traditional methods and the self-excited pulse method separately, and the release times were recorded. The results revealed that the release times for the traditional methods ranged from tens to over a hundred seconds. In contrast, the self-excited pulse method reduced the release time to approximately one second or less. The release speeds for the three materials were enhanced by factors of 90, 97, and 177, respectively. Based on EA pads equipped with self-excited pulse modules, we designed the first untethered electroadhesive microbot, as demonstrated in the vertical climbing scenario on an outdoor tiled wall shown in Fig. 1d. The robot measures 13 cm in length, 18.4 g in weight, and basic structure is illustrated in Fig. 1a. An ultra-lightweight high-voltage power converter 21 addresses the high-voltage requirements of electroadhesion, while Bluetooth communication and a microcontroller enable effective control of the robot. Additionally, the self-excited pulse modules overcome the limitations of slow release speed and adhesion force decay during repeated use, which were previously challenges for electroadhesion. Mechanism characterization of ultrafast de-adhesion The operating process of the self-excited pulse module can be divided into five main stages, as illustrated in Fig. 2 a. The two parallel electrodes acquire charge from the EA pads via a cantilever beam and subsequently function as an external power supply that is periodically connected to the EA pads. This mechanism continuously neutralizes the residual electric field, leading to a rapid de-adhesion. In stage 1, the switch turns on, and a high-voltage supply powers the EA pads. During this stage, the lower electrode plate is connected to the negative terminal of the power supply, while the upper electrode plate remains at a floating potential, and the cantilever beam remains stationary in its initial position. When the switch turns off, the module transitions to stage 2, during which the cantilever beam connects to the high-voltage terminal of the EA pads, receiving positive charges. This causes the cantilever beam to move towards the negatively charged lower electrode under the influence of electrostatic force. Upon contact, a pulsed current, denoted as I 2 is generated. In stage 3, the cantilever beam moves upward due to its elastic restoring force until it touches the upper electrode. At this point, the beam transfers positive charges from the EA pads to the upper electrode, which becomes positively charged. Stage 4 follows, where the cantilever beam moves downward under the combined effects of the elastic restoring force and the electric field force. Upon contacting the lower electrode again, it neutralizes a portion of the charge. Finally, in stage 5, the cantilever beam moves upward again and contacts the upper electrode. At this point, the two electrodes are connected to the EA pads, providing an external electric field to neutralize the residual electric field further. Subsequently, the cantilever beam continues its motion through stages 4 and 5, generating self-excited vibrations. The energy of the self-excited pulse module is derived from the adhesion system, ensuring that the generated output pulse voltage is naturally matched to the system. This makes it particularly effective for de-adhesion, and this adaptability represents a key advantage of the self-excited pulse approach. Each time the cantilever beam contacts the upper electrode, it attains the same potential as the electrode. However, it discharges a portion of its accumulated charge upon contacting the lower electrode. As a result, when the cantilever beam returns to the upper electrode, its potential becomes lower than that of the upper electrode. This potential difference induces the generation of an external electric field from the upper electrode, which acts on the EA pads during each cycle. Over multiple cycles, the adhesion between the EA pads and the substrate progressively decreases, ultimately releasing them. Subsequently, the vibration of the cantilever beam ceases due to the insufficient energy supply. The periodic pulse current employed in the self-excited pulse method is represented by the red line in Fig. 2 b. After several cycles, the EA pads complete the release process, and the pulse current ceases as the vibration of the cantilever beam comes to a halt. In comparison, the traditional release methods, which involve either directly disconnecting the power supply or short-circuiting the two terminals of the EA pads, result in a current that remains consistently low after a single pulse, as depicted by the blue line in Fig. 2 b. This sustained low current reflects the slow decay of the polarized electric field. Figure 2 c illustrates the neutralization of the electric field and the rapid de-adhesion process across the five stages. The electric field within the EA pads and substrate is generated between electrodes. When the EA pads are charged (stage 1), the power supply generates an external electric field, E external , directed from the positive to the negative electrode. Under the influence of this external electric field, the dipoles within the dielectric layer of the EA pads and the substrate become oriented, producing a polarized electric field, E polarized , in the opposite direction to E external . The combined effect of these two fields results in an effective electric field, E effective , which is the vector sum of E external and E polarized . The magnitude of E effective directly determines the changes in adhesion force 22 . The external electric field rapidly disappears after the external power supply is disconnected (stage 2–4). However, due to dielectric relaxation phenomenon 23 , the polarized electric field decays slowly, resulting in a relatively large effective electric field, which makes it difficult to eliminate the adhesion force quickly. Starting from stage 5, the self-excited pulse module periodically applies a new external electric field, E ’ external, to the EA pads. This periodic signal causes the effective electric field to drop rapidly, leading to a rapid de-adhesion. The variations in the external and polarized electric fields described in Fig. 2 c are illustrated in Fig. 2 d. Figure 2 e illustrates the force variation during the adhesion and release process, highlighting that the self-excited pulse method elevates the release speed of EA pads by a factor of 90 compared to traditional methods. After the initial energization, the adhesion force increases rapidly, then rises gradually, and eventually stabilizes at a constant value 24 . The traditional release methods involve directly disconnecting the power supply and docking the two terminals of the EA pads, resulting in a gradual decline in adhesion force. However, the rate of this decline slows over time, requiring an extended period for the force to diminish to a negligible level, with the total release time denoted as ΔT 1 ’. In comparison, the self-excited pulse method markedly accelerates the release process, achieving a total release time of ΔT 1 , with the release time ratio between the two methods reaching 90. The ultrafast wall-climbing motion of the microbot We utilized a mechanical switch to coordinate the robot’s adhesion and motion signals, as shown in Fig. 3 a. The motor-driven system controls the robot’s movement, with the servo motor functioning as a mechanical switch to independently control the adhesion and release of two sets of feet. When either set of EA pads is connected to the high-voltage power supply, it adheres to the wall surface, while connecting the pads to the self-excited pulse module enables rapid de-adhesion. At time t = 0, the servo motor is positioned at angle 1, causing the middle foot to adhere firmly while the drive motor operates until the linkage completes a 180-degree rotation. Subsequently, the servo motor switches to angle 2, transitioning to an adhesion state for the bilateral feet while the middle foot begins to release. The release time of the EA pads, facilitated by the self-excited pulse module, is set to approximately 0.2 seconds. Once the release is complete, the robot finishes half of its motion cycle. The second half of the cycle mirrors the first, except that the initial state transitions from middle-foot adhesion to bilateral feet adhesion. Additionally, due to the weight difference between the two sets of feet, the motor duty cycles for the first and second halves of the motion cycle are not identical. Benefiting from the ultrafast de-adhesion effect of the self-excited pulse method and the precise coordination of control signals, we achieved ultrafast climbing on vertical walls with a legged microbot (weighing 7.1 g and measuring 9.9 cm in body length, shown in Fig. 3 b). The vertical surface used in the experiments was made of release paper, and the robot’s control system is shown in Fig. S3. Within a complete 0.9-second cycle, both the robot’s middle and bilateral feet each completed one adhesion and release sequence, enabling the robot to ascend a vertical distance of 4 cm. This corresponds to a vertical wall-climbing speed of 4.44 cm/s, approximately 0.45 body lengths per second (BL/s). During experiments, each step, including motion and adhesion force transition, takes 0.45 seconds, resulting in a step frequency of 2.2 Hz. Compared to the traditional release method, which operates at a step duration of at least 5.05 seconds (corresponding to a step frequency of 0.2 Hz, as shown in Supplementary Video S1), the climbing speed of the robot is improved by a factor of 11.25. Durability testing and speed comparison of the robot The self-excited pulse method effectively mitigates the decay of adhesion force 17 caused by repeated use, thereby enhancing the durability of EA pads, as shown in Fig. 4 a. Shear adhesion force was selected as the evaluation metric. The data demonstrate that, with the traditional release method, the shear adhesion force of the EA pads decayed significantly after repeated use, showing a 56% attenuation from the initial adhesion force by the 10th cycle. In contrast, the self-excited pulse method exhibited a much lower decay, with only an 11% attenuation in adhesion force after the same number of cycles. This difference in adhesion force decay is also demonstrated in the comparison shown in Supplementary Video S1. The significant decay in adhesion performance during repeated use with the traditional method is attributed to residual charges, which prevent the EA pads from generating a sufficient effective electric field upon reactivation 24 . The self-excited pulse method enables ultrafast de-adhesion and minimal force decay, significantly enhancing the wall-climbing speed of the microbot. As shown in Fig. 4 b, our robot is currently the fastest legged wall-climbing robot among microbots (body length less than 200 mm). Due to the lack of breakthroughs in de-adhesion methods, previously reported microbots for wall climbing have primarily focused on designing driving mechanisms 25–27 , aiming to achieve mechanical release through greater driving forces. However, the charge residue caused by the mechanical release method leads to issues such as force decay after repeated adhesion cycles, which ultimately limits the climbing speed. DISCUSSION By proposing a self-excited pulse module, we provide an electrical ultrafast de-adhesion method that elevates the release speed by more than 90 times while solving the problem of adhesion force decay after multiple reuses by reducing the force decay from 56–11%. As a result, we propose an ultra-fast wall-climbing microbot capable of achieving a vertical climbing speed of 4.44 cm/s (with a step frequency of 2.2Hz), which is 5.6 to 25 times faster than robots using traditional release methods. Furthermore, the robot (weighing 7.1 g and measuring 9.9 cm in body length) exhibits the capability to move efficiently on inverted surfaces, achieving a speed of 2 cm/s with a step frequency of 1 Hz, as demonstrated on a painted ceiling in Supplementary Video S3. The innovative breakthroughs of the self-excited pulse method in de-adhesion speed and durability have significantly expanded the industrial applications of the electroadhesion principle. Wall-climbing robots are expected to become genuinely practical, while the underlying electrostatic mechanisms and circuit configurations offer new perspectives for future research. In the future, to further simplify the self-excited pulse method and improve the robot's utility, research is expected to be carried out in the following areas. For the self-excited pulse method: 1) Exploring the optimal parameters of various materials and structures to maximize the miniaturization and usability of the self-excited pulse module.; 2) Utilizing the characteristics of electrostatic self-excited vibration to realize the non-mechanical start-stop of the self-excited pulse device. For the robot: 1) incorporating closed-loop control to ensure proper wall adherence after each step precisely; 2) designing a multi-legged structure to enable the wall-climbing robot to turn maneuvers and transition between multiple planes, etc. MATERIALS AND METHODS Manufacturing and modeling of Comb-electrode EA pads The EA pads in this experiment feature a three-layer structure consisting of a dielectric, electrode, and insulating layer. A comb-shaped electrode design was adopted to ensure the EA pads generate sufficient adhesive force 28 and achieve faster activation speeds 29 . The fabrication process is illustrated in Fig. S1 a, and the main fabrication steps are as follows: (1) A copper foil tape adhered to an epoxy resin substrate. (2) A laser marking machine (HANS LASER EP-15-THG-S) was used to etch the comb-shaped electrode pattern, removing the excess copper foil. (3) The laser marking machine was further employed to create a complementary pattern of thermal adhesive filler, which was then placed between the electrodes. (4) A layer of epoxy resin was applied to the top of the assembly, followed by baking at high temperatures. Figure S2b illustrates the electric field distribution across the dielectric layer and the substrate, which serves as the primary mechanism driving the EA forces between the EA pad and the insulating substrate. When a high voltage is applied, an electric field is established between the comb electrodes, oriented from the positive to the negative electrode. According to the study on bare electrode debonding by Cao et al. 30 , the polarization of the insulating substrate is identified as the main factor contributing to the slow de-adhesion time of the EA force. Therefore, we simplified the influence of polarization charges within the dielectric layer and primarily focused on the polarization of the substrate 22 . A simplified model of the adhesion electric field was obtained by selecting an electric field line between a pair of positive and negative electrodes that pass through the dielectric layer and the substrate and straightening it along the direction of the electric field. The figure shows that the effective electric field is the vector sum of the external electric field and the polarized electric field, expressed as E effective = |E external - E polarized |. According to Monkman’s polarization theory 31 , the magnitude of the normal EA force can be expressed as Parametric characterization of self-excited pulse module influencing release time In the self-excited pulse method, an observable phenomenon during the acceleration of de-adhesion is the vibration of the conductive cantilever beam. Based on this, we hypothesize that the vibration characteristics of the cantilever beam may influence the release time. Experimental observations indicate that when stimulated by electrical charge, the cantilever beam undergoes self-excited vibration 33 . Notably, the vibration frequency and other parameters are determined solely by the device's properties and are independent of external factors such as applied voltage. To investigate the influence of cantilever beam vibration characteristics on de-adhesion speed, we conducted tests using cantilever beams of varying lengths (and thus different stiffness values) and different plate spacings. The experimental results are presented in Fig. S2. As shown, shorter cantilever beams (i.e., higher stiffness) and smaller plate spacings result in shorter release times. Based on these findings, we propose that during the design of the self-excited pulse module, relevant parameters should be optimized to enable faster vibration of the cantilever beam, thereby achieving rapid de-adhesion. However, it is also crucial to ensure that the cantilever beam is not excessively short and the plate spacing is not overly small, as these conditions may prevent the occurrence of self-excited vibration. Operation process of the electroadhesive wall-climbing robot The wall-climbing robot achieves stable and rapid movement, primarily relying on rapid de-adhesion and precise coordination with its gait cycle. In this study, the robot’s movement is driven by a motor, while a servo motor controls the EA pads, and rapid de-adhesion is facilitated by self-excited pulse modules. The servo motor is equipped with a linkage mechanism, with its two ends connected to the non-grounded terminals of two sets of EA pads. In synchronization with the motor’s motion cycle, the linkage alternates the connection of the corresponding wires to either the high-voltage power supply or the self-excited pulse module, as shown in Fig. S3. The comb-shaped electrode design of the EA pads enables the rapid generation of adhesive forces, while the self-excited pulse module ensures the quick removal of these forces. Declarations Data availability All data generated or analyzed for this paper are included in the published article, its Methods, and its Supplementary information. Original videos and sensor data are available from the corresponding authors on reasonable request. Acknowledgements This work is supported by the National Natural Science Foundation of China (Grant No. 52272384). Any opinions, findings, conclusions, or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Natural Science Foundation of China. Author contribution Mingjing Qi proposed and designed the study. Xiangyu Yang and Jinzhe Peng designed and built the wall-climbing robot. Xiangyu Yang, Wei Shen, Jingyu Che conducted experiments on the robot's structural performance, while Jinzhe Peng and Jingyi Li conducted experiments on the control system. Xiufeng Yang and Ruohan Wang contributed to the design, fabrication, and data analysis of the EA pads. Xiangyu Yang, Jinzhe Peng, Wei Shen, and Mingjing Qi drafted the manuscript. All authors provided feedback and contributed to the final version. Competing interests Authors declare that they have no competing interests. References de Rivaz, S. D. et al. Inverted and vertical climbing of a quadrupedal microrobot using electroadhesion. Science Robotics 3 , eaau3038 (2018). 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The International Journal of Robotics Research 16 , 1–10 (1997). Chen, R. et al. Theoretical and experimental analyses of the dynamic electroadhesion force. Extreme Mechanics Letters 56 , 101892 (2022). Zhu, Y. et al. A 5-mm Untethered Crawling Robot via Self-Excited Electrostatic Vibration. IEEE Transactions on Robotics 38 , 719–730 (2022). Additional Declarations There is NO Competing Interest. Supplementary Files Supplementarymaterials.docx Video1.Roboticclimbingwithdifferentreleasemethods.mp4 Robotic climbing with different release methods Video2.Wallclimbingexperimentsofuntetheredrobots.mp4 Wall-climbing experiments of untethered robots Video3.Roboticinvertedmotionontheceiling.mp4 Robotic inverted motion on the ceiling Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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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-6083110","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":428435217,"identity":"9137b8d1-875e-4027-99b8-ba7391e0d7f4","order_by":0,"name":"Mingjing Qi","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA7ElEQVRIiWNgGAWjYDACZgaGAwwMbDxA1jGoUALRWtjSiNSCADxmxGnhO86deLjgF5+MOf+ab495auwY+NlzDBh+7sCtRfIw74bDM/vYeCxnvN1uzHMsmUGy540BY+8Z3FoMQFp4e9h4DG6c3SbNw8bMYHAjx4CZsY0oLWeeSfP8q2ewJ0oLzw+glvM9bNK8bYcZDCQIaAH7hbcBZAubueHcvuM8EmeeFRzsxaOF7/zZzZ95/hyzNzh/+NmDN9+q5fjbkzc++IlHCygeGRjbgBEvkQDm88AE8Wth+FPDwMCPX90oGAWjYBSMYAAAlQtSUnoxyu4AAAAASUVORK5CYII=","orcid":"https://orcid.org/0000-0002-1423-4663","institution":"Beihang University","correspondingAuthor":true,"prefix":"","firstName":"Mingjing","middleName":"","lastName":"Qi","suffix":""},{"id":428435218,"identity":"d8fc89f2-5fdd-489b-9f87-4b5250b7ac99","order_by":1,"name":"Xiangyu Yang","email":"","orcid":"https://orcid.org/0009-0005-3186-6901","institution":"Beihang University","correspondingAuthor":false,"prefix":"","firstName":"Xiangyu","middleName":"","lastName":"Yang","suffix":""},{"id":428435219,"identity":"fd4dbea1-b269-480e-b8a3-fbde50567ce0","order_by":2,"name":"Jinzhe Peng","email":"","orcid":"https://orcid.org/0009-0006-7167-4979","institution":"Beihang University/ School of Energy and Power Engineering","correspondingAuthor":false,"prefix":"","firstName":"Jinzhe","middleName":"","lastName":"Peng","suffix":""},{"id":428435220,"identity":"d7f9a427-8702-4680-a437-6a3327394bf7","order_by":3,"name":"Wei Shen","email":"","orcid":"","institution":"Beihang University","correspondingAuthor":false,"prefix":"","firstName":"Wei","middleName":"","lastName":"Shen","suffix":""},{"id":428435221,"identity":"fd6772d2-0c29-423a-b5d1-4e245adfefee","order_by":4,"name":"Jingyu Che","email":"","orcid":"","institution":"Beihang University","correspondingAuthor":false,"prefix":"","firstName":"Jingyu","middleName":"","lastName":"Che","suffix":""},{"id":428435222,"identity":"009efec5-fd12-4f94-aced-ab86f86ba640","order_by":5,"name":"Jingyi Li","email":"","orcid":"","institution":"Beihang University","correspondingAuthor":false,"prefix":"","firstName":"Jingyi","middleName":"","lastName":"Li","suffix":""},{"id":428435223,"identity":"13dac9a3-aba1-46f0-8dc0-22c1b3bda95e","order_by":6,"name":"Xiufeng Yang","email":"","orcid":"","institution":"Beihang University","correspondingAuthor":false,"prefix":"","firstName":"Xiufeng","middleName":"","lastName":"Yang","suffix":""},{"id":428435224,"identity":"9c28c6a9-1835-4a8b-bf45-900ed86a7e48","order_by":7,"name":"Ruohan Wang","email":"","orcid":"","institution":"Beihang University","correspondingAuthor":false,"prefix":"","firstName":"Ruohan","middleName":"","lastName":"Wang","suffix":""}],"badges":[],"createdAt":"2025-02-22 04:35:10","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6083110/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6083110/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":78502836,"identity":"38c3ec9f-1c9d-4f36-8d6b-07e1b43b03ba","added_by":"auto","created_at":"2025-03-14 07:10:37","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":281587,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eMechanism and performance of the robot and self-excited pulse module. a, \u003c/strong\u003eThe untethered robot, weighing 18.4 g and measuring 13 cm in length along the forward direction, primarily comprises self-excited pulse modules, a high-voltage power system, a drive and transmission system, and electroadhesive pads. \u003cstrong\u003eb,\u003c/strong\u003eThe self-excited pulse module consists of two parallel conductive electrodes and a conductive cantilever beam, which vibrates due to residual charge when the charged EA pads are connected to the module. \u003cstrong\u003ec,\u003c/strong\u003e Release times of EA pads using two different methods (plotted on a log10 logarithmic scale): the self-excited pulse method elevates the release speed by more than 90-fold on all three surfaces. Error bars indicate mean ±1 SD. \u003cstrong\u003ed,\u003c/strong\u003e The untethered robot performs vertical motion on the outdoor tiled wall.\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-6083110/v1/36ce5d7eac4922fa50f65808.png"},{"id":78502392,"identity":"7b06c26c-2bf9-4983-aa44-e9243e624551","added_by":"auto","created_at":"2025-03-14 07:02:37","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":293531,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eWorking mechanism and parameter characteristics of the self-excited pulse module. a,\u003c/strong\u003eThe five main stages in the operation of the EA pads system include switching on the high-voltage power supply and connecting the self-excited pulse module. \u003cstrong\u003eb,\u003c/strong\u003eComparison of the current between the self-excited pulse method and the traditional method during the release of EA pads. \u003cstrong\u003ec,\u003c/strong\u003e The distribution of the electric field and electric dipoles within the dielectric layer and substrate in the five stages. \u003cstrong\u003ed, \u003c/strong\u003eThe variation in electric field strength across the five stages of the EA pads system. \u003cstrong\u003ee, \u003c/strong\u003eAdhesion force variation of EA pads during operation: the release speed using the self-excited pulse method is 90 times faster than that of traditional methods.\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-6083110/v1/3d816ae068fd9188dcd3b7bb.png"},{"id":78503115,"identity":"a46e121f-b9f8-4f36-b68d-516cdba766db","added_by":"auto","created_at":"2025-03-14 07:18:37","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":321974,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eControlled wall-climbing motion of the robot. a,\u003c/strong\u003e State transitions of the motor, servo, and two sets of EA pads during a complete motion cycle. \u003cstrong\u003eb, \u003c/strong\u003eClimbing process of the robot on a vertical wall: within a 0.9-second cycle, the climbing height is 4 cm. The first half-cycle includes a movement time of 0.21 seconds and an adhesion state transition time of 0.24 seconds, while the second half-cycle includes a movement time of 0.23 seconds and an adhesion state transition time of 0.22 seconds.\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-6083110/v1/c507c164453c7619cae1785f.png"},{"id":78502834,"identity":"22be5e6e-03e5-47d1-bdd4-0bb59ef0896d","added_by":"auto","created_at":"2025-03-14 07:10:37","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":130381,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eRepeated adhesion performance and robot climbing speed comparison. a,\u003c/strong\u003e Adhesion force decay comparison after repeated use of the EA pads. The error band indicates the mean ± 1 SD of the data. \u003cstrong\u003eb,\u003c/strong\u003e Comparison of vertical climbing speeds of legged microbots: the robot presented in this work is 5.6 to 25 times faster than previous robots.\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-6083110/v1/6fcfd91ca0dde88ea5f6a893.png"},{"id":78504241,"identity":"7bc3ca10-4699-4599-9f92-8f832bfbff8e","added_by":"auto","created_at":"2025-03-14 07:34:37","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1771927,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6083110/v1/81c95811-0b12-4f32-9f14-5569adb95599.pdf"},{"id":78502381,"identity":"d4498d1a-1c48-4d66-bc74-e26bada883e1","added_by":"auto","created_at":"2025-03-14 07:02:37","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":331197,"visible":true,"origin":"","legend":"","description":"","filename":"Supplementarymaterials.docx","url":"https://assets-eu.researchsquare.com/files/rs-6083110/v1/b30761dfe63ede5a8a5bd405.docx"},{"id":78502398,"identity":"90c011c8-b466-4eca-9d79-4aab1d864d5c","added_by":"auto","created_at":"2025-03-14 07:02:39","extension":"mp4","order_by":3,"title":"","display":"","copyAsset":false,"role":"supplement","size":52021030,"visible":true,"origin":"","legend":"Robotic climbing with different release methods","description":"","filename":"Video1.Roboticclimbingwithdifferentreleasemethods.mp4","url":"https://assets-eu.researchsquare.com/files/rs-6083110/v1/b4153226adeba1a223ac39d3.mp4"},{"id":78502397,"identity":"4c40f042-cabe-450a-bfba-6e705a61bf90","added_by":"auto","created_at":"2025-03-14 07:02:38","extension":"mp4","order_by":4,"title":"","display":"","copyAsset":false,"role":"supplement","size":23995117,"visible":true,"origin":"","legend":"\u003cp\u003eWall-climbing experiments of untethered robots\u003c/p\u003e","description":"","filename":"Video2.Wallclimbingexperimentsofuntetheredrobots.mp4","url":"https://assets-eu.researchsquare.com/files/rs-6083110/v1/74303ee81d1386b7fc75f243.mp4"},{"id":78502396,"identity":"b8cdda47-0c61-4e83-acea-9bca59e269c5","added_by":"auto","created_at":"2025-03-14 07:02:37","extension":"mp4","order_by":5,"title":"","display":"","copyAsset":false,"role":"supplement","size":16235567,"visible":true,"origin":"","legend":"Robotic inverted motion on the ceiling","description":"","filename":"Video3.Roboticinvertedmotionontheceiling.mp4","url":"https://assets-eu.researchsquare.com/files/rs-6083110/v1/3c64596e0078e2ea832c2e6c.mp4"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"Wall-climbing microbots with ultrafast de-adhesion","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eClimbing represents a critical survival skill for many small animals in nature, such as geckos, providing significant advantages in predation, evasion, and shelter acquisition through rapid climbing enabled by adhesion mechanisms. Similarly, specialized robots\u003csup\u003e1\u0026ndash;4\u003c/sup\u003e often require adhesion and climbing capabilities to execute tasks such as exploration and transportation\u003csup\u003e5\u0026ndash;7\u003c/sup\u003e. However, existing adhesion techniques face several limitations\u003csup\u003e8\u003c/sup\u003e. For instance, vacuum adhesion\u003csup\u003e9,10\u003c/sup\u003e demands smooth, non-porous surfaces; magnetic adhesion is confined to ferromagnetic materials; and bionic adhesion often exhibits low payload capacity and is highly sensitive to surface conditions, such as dust.\u003c/p\u003e\n\u003cp\u003eElectroadhesion (EA) presents a promising alternative, which can generate adhesion forces on a wide range of surfaces\u003csup\u003e11\u003c/sup\u003e. This method provides controllable adhesion through electrical signals while maintaining minimal power consumption. However, existing EA technologies face significant challenges, particularly a slow de-adhesion speed caused by residual charges after power is turned off\u003csup\u003e12\u003c/sup\u003e. These residual charges create an electric field that sustains unwanted adhesion forces, and over time, the accumulation of such charges significantly diminishes adhesion efficacy\u003csup\u003e13\u003c/sup\u003e. To address the issue of slow release, early industrial EA grippers commonly relied on mechanical methods\u003csup\u003e14\u0026ndash;16\u003c/sup\u003e, which pose risks of substrate damage\u003csup\u003e17\u003c/sup\u003e and bring a more than 50% decay\u003csup\u003e1\u003c/sup\u003e in EA force after several adhesion-release cycles.\u003c/p\u003e\n\u003cp\u003eThis paper presents a wall-climbing microbot (Fig.\u0026nbsp;1a) with ultrafast de-adhesion via a novel electrical control\u003csup\u003e18,19\u003c/sup\u003e method. This approach leverages a self-excited pulse module (Fig. 1b) integrated into the driving circuit of the EA pads. By effectively neutralizing the residual electric field\u003csup\u003e20\u003c/sup\u003e, the EA pads achieve release at a speed exceeding 90 times that of traditional methods (Fig. 1c). Moreover, the issue of residual charge accumulation is addressed, thereby reducing the adhesion force decay after repeated use from 56\u0026ndash;11%. Finally, we developed the fastest legged wall-climbing microbot (Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eb, Supplementary Video S1) and the first untethered electroadhesive microbot (Fig. 1d, Supplementary Video S2).\u003c/p\u003e"},{"header":"RESULTS","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eRobot and self-excited pulse module design\u003c/h2\u003e \u003cp\u003eFigure 1a describes the general design and specific composition of the robot. The untethered wall-climbing robot primarily comprises electroadhesive (EA) pads, a drive and transmission system, a high-voltage power system, and self-excited pulse modules. During operation, the drive motors enable the middle and bilateral feet to alternate contact with the wall. At the same time, the high-voltage power system charges the EA pads to generate adhesion force. A servo functions as a double-throw switch, controlling the adhesion and release of EA pads on the middle and bilateral. Adhesion force is generated immediately upon contact of each set of pads with the wall and is rapidly removed just before the pads are released from the surface.\u003c/p\u003e \u003cp\u003eFigure 1b shows the principle and configuration of the self-excited pulse module, an innovative electromechanical coupling device specifically designed to facilitate the rapid de-adhesion of EA pads. The module primarily comprises a switch, a conductive cantilever beam, and a pair of conductive parallel electrodes-one connected to the negative terminal of the power supply, while the other is maintained at a floating potential. The core component of this module is the conductive cantilever beam, which can be excited into vibration between two parallel electrodes due to residual charge within the EA pads and the substrate. This vibration generates a periodic pulse voltage signal, producing a periodic external electric field applied to the EA pads. This external field is tuned to match the adhesion parameters, effectively neutralizing the residual electric field and enabling rapid de-adhesion of the EA pads.\u003c/p\u003e \u003cp\u003eExperimental results demonstrate that the self-excited pulse method can enhance the de-adhesion speed by more than 90-fold, as illustrated in Fig.\u0026nbsp;1c. Three lightweight materials\u0026mdash;fabric, wood, and release paper (material parameters provided in Table \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e)\u0026mdash;were selected as adhesion substrates. After these substrates were adhered to the robotic arm-operated EA pad, they were released using the traditional methods and the self-excited pulse method separately, and the release times were recorded. The results revealed that the release times for the traditional methods ranged from tens to over a hundred seconds. In contrast, the self-excited pulse method reduced the release time to approximately one second or less. The release speeds for the three materials were enhanced by factors of 90, 97, and 177, respectively.\u003c/p\u003e \u003cp\u003eBased on EA pads equipped with self-excited pulse modules, we designed the first untethered electroadhesive microbot, as demonstrated in the vertical climbing scenario on an outdoor tiled wall shown in Fig.\u0026nbsp;1d. The robot measures 13 cm in length, 18.4 g in weight, and basic structure is illustrated in Fig.\u0026nbsp;1a. An ultra-lightweight high-voltage power converter\u003csup\u003e21\u003c/sup\u003e addresses the high-voltage requirements of electroadhesion, while Bluetooth communication and a microcontroller enable effective control of the robot. Additionally, the self-excited pulse modules overcome the limitations of slow release speed and adhesion force decay during repeated use, which were previously challenges for electroadhesion.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eMechanism characterization of ultrafast de-adhesion\u003c/h3\u003e\n\u003cp\u003eThe operating process of the self-excited pulse module can be divided into five main stages, as illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e2\u003c/span\u003ea. The two parallel electrodes acquire charge from the EA pads via a cantilever beam and subsequently function as an external power supply that is periodically connected to the EA pads. This mechanism continuously neutralizes the residual electric field, leading to a rapid de-adhesion. In stage 1, the switch turns on, and a high-voltage supply powers the EA pads. During this stage, the lower electrode plate is connected to the negative terminal of the power supply, while the upper electrode plate remains at a floating potential, and the cantilever beam remains stationary in its initial position. When the switch turns off, the module transitions to stage 2, during which the cantilever beam connects to the high-voltage terminal of the EA pads, receiving positive charges. This causes the cantilever beam to move towards the negatively charged lower electrode under the influence of electrostatic force. Upon contact, a pulsed current, denoted as I\u003csub\u003e2\u003c/sub\u003e is generated. In stage 3, the cantilever beam moves upward due to its elastic restoring force until it touches the upper electrode. At this point, the beam transfers positive charges from the EA pads to the upper electrode, which becomes positively charged. Stage 4 follows, where the cantilever beam moves downward under the combined effects of the elastic restoring force and the electric field force. Upon contacting the lower electrode again, it neutralizes a portion of the charge. Finally, in stage 5, the cantilever beam moves upward again and contacts the upper electrode. At this point, the two electrodes are connected to the EA pads, providing an external electric field to neutralize the residual electric field further. Subsequently, the cantilever beam continues its motion through stages 4 and 5, generating self-excited vibrations.\u003c/p\u003e \u003cp\u003eThe energy of the self-excited pulse module is derived from the adhesion system, ensuring that the generated output pulse voltage is naturally matched to the system. This makes it particularly effective for de-adhesion, and this adaptability represents a key advantage of the self-excited pulse approach. Each time the cantilever beam contacts the upper electrode, it attains the same potential as the electrode. However, it discharges a portion of its accumulated charge upon contacting the lower electrode. As a result, when the cantilever beam returns to the upper electrode, its potential becomes lower than that of the upper electrode. This potential difference induces the generation of an external electric field from the upper electrode, which acts on the EA pads during each cycle. Over multiple cycles, the adhesion between the EA pads and the substrate progressively decreases, ultimately releasing them. Subsequently, the vibration of the cantilever beam ceases due to the insufficient energy supply.\u003c/p\u003e \u003cp\u003eThe periodic pulse current employed in the self-excited pulse method is represented by the red line in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e2\u003c/span\u003eb. After several cycles, the EA pads complete the release process, and the pulse current ceases as the vibration of the cantilever beam comes to a halt. In comparison, the traditional release methods, which involve either directly disconnecting the power supply or short-circuiting the two terminals of the EA pads, result in a current that remains consistently low after a single pulse, as depicted by the blue line in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e2\u003c/span\u003eb. This sustained low current reflects the slow decay of the polarized electric field.\u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e2\u003c/span\u003ec illustrates the neutralization of the electric field and the rapid de-adhesion process across the five stages. The electric field within the EA pads and substrate is generated between electrodes. When the EA pads are charged (stage 1), the power supply generates an external electric field, E\u003csub\u003eexternal\u003c/sub\u003e, directed from the positive to the negative electrode. Under the influence of this external electric field, the dipoles within the dielectric layer of the EA pads and the substrate become oriented, producing a polarized electric field, E\u003csub\u003epolarized\u003c/sub\u003e, in the opposite direction to E\u003csub\u003eexternal\u003c/sub\u003e. The combined effect of these two fields results in an effective electric field, E\u003csub\u003eeffective\u003c/sub\u003e, which is the vector sum of E\u003csub\u003eexternal\u003c/sub\u003e and E\u003csub\u003epolarized\u003c/sub\u003e. The magnitude of E\u003csub\u003eeffective\u003c/sub\u003e directly determines the changes in adhesion force\u003csup\u003e22\u003c/sup\u003e. The external electric field rapidly disappears after the external power supply is disconnected (stage 2\u0026ndash;4). However, due to dielectric relaxation phenomenon\u003csup\u003e23\u003c/sup\u003e, the polarized electric field decays slowly, resulting in a relatively large effective electric field, which makes it difficult to eliminate the adhesion force quickly. Starting from stage 5, the self-excited pulse module periodically applies a new external electric field, E\u003cb\u003e\u0026rsquo;\u003c/b\u003e external, to the EA pads. This periodic signal causes the effective electric field to drop rapidly, leading to a rapid de-adhesion. The variations in the external and polarized electric fields described in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e2\u003c/span\u003ec are illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e2\u003c/span\u003ed.\u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e2\u003c/span\u003ee illustrates the force variation during the adhesion and release process, highlighting that the self-excited pulse method elevates the release speed of EA pads by a factor of 90 compared to traditional methods. After the initial energization, the adhesion force increases rapidly, then rises gradually, and eventually stabilizes at a constant value\u003csup\u003e24\u003c/sup\u003e. The traditional release methods involve directly disconnecting the power supply and docking the two terminals of the EA pads, resulting in a gradual decline in adhesion force. However, the rate of this decline slows over time, requiring an extended period for the force to diminish to a negligible level, with the total release time denoted as ΔT\u003csub\u003e1\u003c/sub\u003e\u0026rsquo;. In comparison, the self-excited pulse method markedly accelerates the release process, achieving a total release time of ΔT\u003csub\u003e1\u003c/sub\u003e, with the release time ratio between the two methods reaching 90.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eThe ultrafast wall-climbing motion of the microbot\u003c/h3\u003e\n\u003cp\u003eWe utilized a mechanical switch to coordinate the robot\u0026rsquo;s adhesion and motion signals, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003ea. The motor-driven system controls the robot\u0026rsquo;s movement, with the servo motor functioning as a mechanical switch to independently control the adhesion and release of two sets of feet. When either set of EA pads is connected to the high-voltage power supply, it adheres to the wall surface, while connecting the pads to the self-excited pulse module enables rapid de-adhesion. At time t\u0026thinsp;=\u0026thinsp;0, the servo motor is positioned at angle 1, causing the middle foot to adhere firmly while the drive motor operates until the linkage completes a 180-degree rotation. Subsequently, the servo motor switches to angle 2, transitioning to an adhesion state for the bilateral feet while the middle foot begins to release. The release time of the EA pads, facilitated by the self-excited pulse module, is set to approximately 0.2 seconds. Once the release is complete, the robot finishes half of its motion cycle. The second half of the cycle mirrors the first, except that the initial state transitions from middle-foot adhesion to bilateral feet adhesion. Additionally, due to the weight difference between the two sets of feet, the motor duty cycles for the first and second halves of the motion cycle are not identical.\u003c/p\u003e \u003cp\u003eBenefiting from the ultrafast de-adhesion effect of the self-excited pulse method and the precise coordination of control signals, we achieved ultrafast climbing on vertical walls with a legged microbot (weighing 7.1 g and measuring 9.9 cm in body length, shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003eb). The vertical surface used in the experiments was made of release paper, and the robot\u0026rsquo;s control system is shown in Fig. S3. Within a complete 0.9-second cycle, both the robot\u0026rsquo;s middle and bilateral feet each completed one adhesion and release sequence, enabling the robot to ascend a vertical distance of 4 cm. This corresponds to a vertical wall-climbing speed of 4.44 cm/s, approximately 0.45 body lengths per second (BL/s). During experiments, each step, including motion and adhesion force transition, takes 0.45 seconds, resulting in a step frequency of 2.2 Hz. Compared to the traditional release method, which operates at a step duration of at least 5.05 seconds (corresponding to a step frequency of 0.2 Hz, as shown in Supplementary Video S1), the climbing speed of the robot is improved by a factor of 11.25.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eDurability testing and speed comparison of the robot\u003c/h3\u003e\n\u003cp\u003eThe self-excited pulse method effectively mitigates the decay of adhesion force\u003csup\u003e17\u003c/sup\u003e caused by repeated use, thereby enhancing the durability of EA pads, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e4\u003c/span\u003ea. Shear adhesion force was selected as the evaluation metric. The data demonstrate that, with the traditional release method, the shear adhesion force of the EA pads decayed significantly after repeated use, showing a 56% attenuation from the initial adhesion force by the 10th cycle. In contrast, the self-excited pulse method exhibited a much lower decay, with only an 11% attenuation in adhesion force after the same number of cycles. This difference in adhesion force decay is also demonstrated in the comparison shown in Supplementary Video S1. The significant decay in adhesion performance during repeated use with the traditional method is attributed to residual charges, which prevent the EA pads from generating a sufficient effective electric field upon reactivation\u003csup\u003e24\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe self-excited pulse method enables ultrafast de-adhesion and minimal force decay, significantly enhancing the wall-climbing speed of the microbot. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e4\u003c/span\u003eb, our robot is currently the fastest legged wall-climbing robot among microbots (body length less than 200 mm). Due to the lack of breakthroughs in de-adhesion methods, previously reported microbots for wall climbing have primarily focused on designing driving mechanisms\u003csup\u003e25\u0026ndash;27\u003c/sup\u003e, aiming to achieve mechanical release through greater driving forces. However, the charge residue caused by the mechanical release method leads to issues such as force decay after repeated adhesion cycles, which ultimately limits the climbing speed.\u003c/p\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eBy proposing a self-excited pulse module, we provide an electrical ultrafast de-adhesion method that elevates the release speed by more than 90 times while solving the problem of adhesion force decay after multiple reuses by reducing the force decay from 56\u0026ndash;11%. As a result, we propose an ultra-fast wall-climbing microbot capable of achieving a vertical climbing speed of 4.44 cm/s (with a step frequency of 2.2Hz), which is 5.6 to 25 times faster than robots using traditional release methods. Furthermore, the robot (weighing 7.1 g and measuring 9.9 cm in body length) exhibits the capability to move efficiently on inverted surfaces, achieving a speed of 2 cm/s with a step frequency of 1 Hz, as demonstrated on a painted ceiling in Supplementary Video S3. The innovative breakthroughs of the self-excited pulse method in de-adhesion speed and durability have significantly expanded the industrial applications of the electroadhesion principle. Wall-climbing robots are expected to become genuinely practical, while the underlying electrostatic mechanisms and circuit configurations offer new perspectives for future research.\u003c/p\u003e \u003cp\u003eIn the future, to further simplify the self-excited pulse method and improve the robot's utility, research is expected to be carried out in the following areas. For the self-excited pulse method: 1) Exploring the optimal parameters of various materials and structures to maximize the miniaturization and usability of the self-excited pulse module.; 2) Utilizing the characteristics of electrostatic self-excited vibration to realize the non-mechanical start-stop of the self-excited pulse device. For the robot: 1) incorporating closed-loop control to ensure proper wall adherence after each step precisely; 2) designing a multi-legged structure to enable the wall-climbing robot to turn maneuvers and transition between multiple planes, etc.\u003c/p\u003e"},{"header":"MATERIALS AND METHODS","content":"\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e\n \u003ch2\u003eManufacturing and modeling of Comb-electrode EA pads\u003c/h2\u003e\n \u003cp\u003eThe EA pads in this experiment feature a three-layer structure consisting of a dielectric, electrode, and insulating layer. A comb-shaped electrode design was adopted to ensure the EA pads generate sufficient adhesive force\u003csup\u003e28\u003c/sup\u003e and achieve faster activation speeds\u003csup\u003e29\u003c/sup\u003e. The fabrication process is illustrated in Fig. \u003cspan class=\"InternalRef\"\u003eS1\u003c/span\u003ea, and the main fabrication steps are as follows: (1) A copper foil tape adhered to an epoxy resin substrate. (2) A laser marking machine (HANS LASER EP-15-THG-S) was used to etch the comb-shaped electrode pattern, removing the excess copper foil. (3) The laser marking machine was further employed to create a complementary pattern of thermal adhesive filler, which was then placed between the electrodes. (4) A layer of epoxy resin was applied to the top of the assembly, followed by baking at high temperatures.\u003c/p\u003e\n \u003cp\u003eFigure S2b illustrates the electric field distribution across the dielectric layer and the substrate, which serves as the primary mechanism driving the EA forces between the EA pad and the insulating substrate. When a high voltage is applied, an electric field is established between the comb electrodes, oriented from the positive to the negative electrode. According to the study on bare electrode debonding by Cao et al.\u003csup\u003e30\u003c/sup\u003e, the polarization of the insulating substrate is identified as the main factor contributing to the slow de-adhesion time of the EA force. Therefore, we simplified the influence of polarization charges within the dielectric layer and primarily focused on the polarization of the substrate\u003csup\u003e22\u003c/sup\u003e. A simplified model of the adhesion electric field was obtained by selecting an electric field line between a pair of positive and negative electrodes that pass through the dielectric layer and the substrate and straightening it along the direction of the electric field. The figure shows that the effective electric field is the vector sum of the external electric field and the polarized electric field, expressed as E\u003csub\u003eeffective\u003c/sub\u003e = |E\u003csub\u003eexternal\u003c/sub\u003e - E\u003csub\u003epolarized\u003c/sub\u003e |.\u003c/p\u003e\n \u003cp\u003eAccording to Monkman\u0026rsquo;s polarization theory\u003csup\u003e31\u003c/sup\u003e, the magnitude of the normal EA force can be expressed as\u003c/p\u003e\n \u003cdiv id=\"Equ1\" class=\"Equation\"\u003e\n \u003cdiv class=\"EquationNumber\"\u003e\u003cimg 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\"\u003e\u003c/div\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Equ2\" class=\"Equation\"\u003e\u003cbr\u003e\u003c/div\u003e\n \n\u003c/div\u003e\n\u003ch3\u003eParametric characterization of self-excited pulse module influencing release time\u003c/h3\u003e\n\u003cp\u003eIn the self-excited pulse method, an observable phenomenon during the acceleration of de-adhesion is the vibration of the conductive cantilever beam. Based on this, we hypothesize that the vibration characteristics of the cantilever beam may influence the release time. Experimental observations indicate that when stimulated by electrical charge, the cantilever beam undergoes self-excited vibration\u003csup\u003e33\u003c/sup\u003e. Notably, the vibration frequency and other parameters are determined solely by the device's properties and are independent of external factors such as applied voltage.\u003c/p\u003e \u003cp\u003eTo investigate the influence of cantilever beam vibration characteristics on de-adhesion speed, we conducted tests using cantilever beams of varying lengths (and thus different stiffness values) and different plate spacings. The experimental results are presented in Fig. S2. As shown, shorter cantilever beams (i.e., higher stiffness) and smaller plate spacings result in shorter release times. Based on these findings, we propose that during the design of the self-excited pulse module, relevant parameters should be optimized to enable faster vibration of the cantilever beam, thereby achieving rapid de-adhesion. However, it is also crucial to ensure that the cantilever beam is not excessively short and the plate spacing is not overly small, as these conditions may prevent the occurrence of self-excited vibration.\u003c/p\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eOperation process of the electroadhesive wall-climbing robot\u003c/h2\u003e \u003cp\u003eThe wall-climbing robot achieves stable and rapid movement, primarily relying on rapid de-adhesion and precise coordination with its gait cycle. In this study, the robot\u0026rsquo;s movement is driven by a motor, while a servo motor controls the EA pads, and rapid de-adhesion is facilitated by self-excited pulse modules. The servo motor is equipped with a linkage mechanism, with its two ends connected to the non-grounded terminals of two sets of EA pads. In synchronization with the motor\u0026rsquo;s motion cycle, the linkage alternates the connection of the corresponding wires to either the high-voltage power supply or the self-excited pulse module, as shown in Fig. S3. The comb-shaped electrode design of the EA pads enables the rapid generation of adhesive forces, while the self-excited pulse module ensures the quick removal of these forces.\u003c/p\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll data generated or analyzed for this paper are included in the published article, its Methods, and its Supplementary information. Original videos and sensor data are available from the corresponding authors on reasonable request.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work is supported by the National Natural Science Foundation of China (Grant No. 52272384). Any opinions, findings, conclusions, or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Natural Science Foundation of China.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contribution\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eMingjing Qi proposed and designed the study. Xiangyu Yang and Jinzhe Peng designed and built the wall-climbing robot. Xiangyu Yang, Wei Shen, Jingyu Che conducted experiments on the robot\u0026apos;s structural performance, while Jinzhe Peng and Jingyi Li conducted experiments on the control system. Xiufeng Yang and Ruohan Wang contributed to the design, fabrication, and data analysis of the EA pads. Xiangyu Yang, Jinzhe Peng, Wei Shen, and Mingjing Qi drafted the manuscript. All authors provided feedback and contributed to the final version.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAuthors declare that they have no competing interests.\u003cbr\u003e\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003ede Rivaz, S. D. \u003cem\u003eet al.\u003c/em\u003e Inverted and vertical climbing of a quadrupedal microrobot using electroadhesion. \u003cem\u003eScience Robotics\u003c/em\u003e \u003cstrong\u003e3\u003c/strong\u003e, eaau3038 (2018).\u003c/li\u003e\n\u003cli\u003eGu, G., Zou, J., Zhao, R., Zhao, X. \u0026amp; Zhu, X. 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Electroadhesion (EA) stands out for its wide applicability, simple control, and low power consumption among various adhesion methods. However, its practical use is limited by the slow de-adhesion speed. In this study, we propose a novel method by introducing a self-excited pulse module into the driving circuit of EA pads. During the de-adhesion process, the residual charges induce self-excited vibrations of the cantilever beam within the module, generating an external pulsed electric field that matches the EA pads. This external field neutralizes the residual electric field, enabling ultrafast release. The proposed method elevates the release speed of EA pads by more than 90 times and reduces the adhesion force decay after repeated use from 56\u0026ndash;11%. We developed an ultrafast wall-climbing microbot based on this method, achieving a climbing speed of 4.44 cm/s (with a step frequency of 2.2Hz), which is 5.6 to 25 times faster than the robots using traditional release methods. Furthermore, we developed the first untethered electroadhesive microbot by integrating a high-voltage power system.\u003c/p\u003e","manuscriptTitle":"Wall-climbing microbots with ultrafast de-adhesion","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-03-14 07:02:32","doi":"10.21203/rs.3.rs-6083110/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"dbe8c8e0-1a24-4a06-9744-cef2e059fc74","owner":[],"postedDate":"March 14th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":45646170,"name":"Physical sciences/Engineering/Electrical and electronic engineering"},{"id":45646171,"name":"Physical sciences/Engineering/Mechanical engineering"}],"tags":[],"updatedAt":"2025-03-14T07:02:32+00:00","versionOfRecord":[],"versionCreatedAt":"2025-03-14 07:02:32","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6083110","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6083110","identity":"rs-6083110","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}