journal article·2025-12-24Open access

Ultrathin bending sensor with ultrahigh robustness and reliability for robotic applications

Hao Liu, Masahito Takakuwa, Michitaka Yamamoto, Shinsuke Nakashima, Zhengyi Jiang, Tomoyuki Yokota, Takao Someya, Toshihiro Itoh, Seiichi Takamatsu

npj Flexible Electronics· Volume 9· Issue 1

Abstract

Soft bending sensors offer high sensitivity and a large deformation range, making them ideal for robotics and healthcare. However, existing sensors made from organic materials often fail under large tensile stresses and long-term bending, limiting their real-world applications. This paper presents the 100,000+ cycle-reliable bending sensor (100k+ CRBS), which leverages the flexibility and elastic response of an ultrathin piezoresistive silicon gauge integrated with highly resilient polyimide film by the water vapor plasma-assisted bonding method for both high robustness and reliability. The 100k+ CRBS endured over 100,000 bending cycles at a radius of 5 mm. Additionally, it achieved a remarkable minimum bending radius of 0.4 mm. It also exhibited a mechanical limit of 300 MPa, while maintaining stable operation below 94 MPa (<3% strain). These features enable precision motion capture in demanding applications including human–machine interaction, healthcare and rehabilitation, and smart industry and automation.
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Research context

OpenAlex topics: Advanced Sensor and Energy Harvesting Materials · Soft Robotics and Applications · Advanced MEMS and NEMS Technologies

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References (44)

Show source-provided references
1. Zhu, M. et al. Haptic-feedback smart glove as a creative human-machine interface (HMI) for virtual/augmented reality applications. Sci. Adv. 6, eaaz8693 (2020).10.1126/sciadv.aaz8693 ↗
2. Li, T. et al. Bioinspired stretchable fiber-based sensor toward intelligent human–machine interactions. ACS Appl. Mater. Interfaces 14, 22666–22677 (2022).10.1021/acsami.2c05823 ↗
3. Kim, K. K. et al. A deep-learned skin sensor decoding the epicentral human motions. Nat. Commun. 11, 2149 (2020).10.1038/s41467-020-16040-y ↗
4. Dagdeviren, C. et al. Conformal piezoelectric energy harvesting and storage from motions of the heart, lung, and diaphragm. Proc. Natl. Acad. Sci. USA 111, 1927–1932 (2014).10.1073/pnas.1317233111 ↗
5. Su, Y. et al. A high-payload proprioceptive hybrid robotic gripper with soft origamic actuators. IEEE Robot. Autom. Lett. 5, 3003–3010 (2020).10.1109/LRA.2020.2974438 ↗
6. Shintake, J., Cacucciolo, V., Floreano, D. & Shea, H. Soft robotic grippers. Adv. Mater. 30, 1707035 (2018).10.1002/adma.201707035 ↗
7. Brown, E. et al. Universal robotic gripper based on the jamming of granular material. Proc. Natl. Acad. Sci. USA 107, 18809–18814 (2010).10.1073/pnas.1003250107 ↗
8. Bártolo, P. & Bidanda, B. (eds) Bio-materials and Prototyping Applications in Medicine (Springer, 2008).10.1007/978-0-387-47683-4 ↗
9. Bai, H. et al. Stretchable distributed fiber-optic sensors. Science 370, 848–852 (2020).10.1126/science.aba5504 ↗
10. Li, J. et al. Plastic-optical-fiber-enabled smart glove for machine-learning-based gesture recognition. IEEE Trans. Ind. Electron. 71, 4252–4261 (2024).10.1109/TIE.2023.3277119 ↗
11. Gan, J., Yang, A., Guo, Q. & Yang, Z. Flexible optical fiber sensing: materials, methodologies, and applications. Adv. Devices Instrum. 5, 0046 (2024).10.34133/adi.0046 ↗
12. Jang, M., Kim, J. S., Um, S. H., Yang, S. & Kim, J. Ultra-high curvature sensors for multi-bend structures using fiber Bragg gratings. Opt. Express 27, 2074 (2019).10.1364/OE.27.002074 ↗
13. Shi, F. et al. Miniature optical fiber curvature sensor via integration with GaN optoelectronics. Commun. Eng. 1, 47 (2022).10.1038/s44172-022-00049-w ↗
14. Zhao, H., O’Brien, K., Li, S. & Shepherd, R. F. Optoelectronically innervated soft prosthetic hand via stretchable optical waveguides. Sci. Robot. 1, eaai7529 (2016).10.1126/scirobotics.aai7529 ↗
15. Chen, H. et al. Omnidirectional bending and pressure sensor based on stretchable CNT-PU sponge. Adv. Funct. Mater. 27, 1604434 (2017).10.1002/adfm.201604434 ↗
16. Min, P. et al. Rational design of soft yet elastic lamellar graphene aerogels via bidirectional freezing for ultrasensitive pressure and bending sensors. Adv. Funct. Mater. 31, 2103703 (2021).10.1002/adfm.202103703 ↗
17. Yoo, J. et al. Industrial grade, bending-insensitive, transparent nanoforce touch sensor via enhanced percolation effect in a hierarchical nanocomposite film. Adv. Funct. Mater. 28, 1804721 (2018).10.1002/adfm.201804721 ↗
18. Wei, Y. et al. Highly stable and sensitive paper-based bending sensor using silver nanowires/layered double hydroxides hybrids. ACS Appl. Mater. Interfaces 7, 14182–14191 (2015).10.1021/acsami.5b03824 ↗
19. Lee, D. H. et al. Bending sensor based on controlled microcracking regions for application toward wearable electronics and robotics. ACS Appl. Mater. Interfaces 14, 31312–31320 (2022).10.1021/acsami.2c07795 ↗
20. Liao, X., Zhang, Z., Liang, Q., Liao, Q. & Zhang, Y. Flexible, cuttable, and self-waterproof bending strain sensors using microcracked gold nanofilms@paper substrate. ACS Appl. Mater. Interfaces 9, 4151–4158 (2017).10.1021/acsami.6b12991 ↗
21. Liu, J. et al. Digitizing human motion via bending sensors toward humanoid robot. Adv. Intell. Syst. 5, 2200337 (2023).10.1002/aisy.202200337 ↗
22. Li, Z. et al. Fiber-junction design for directional bending sensors. npj Flex. Electron. 5, 4 (2021).10.1038/s41528-021-00102-2 ↗
23. Cao, Y. et al. An easy-to-install textile bending sensor with high sensitivity, linearity, and multidirection direction capability. Adv. Mater. Technol. 7, 2100830 (2022).10.1002/admt.202100830 ↗
24. Yang, S. & Lu, N. Gauge factor and stretchability of silicon-on-polymer strain gauges. Sensors 13, 8577–8594 (2013).10.3390/s130708577 ↗
25. Smith, C. S. Piezoresistance effect in germanium and silicon. Phys. Rev. 94, 42–49 (1954).10.1103/PhysRev.94.42 ↗
26. Petersen, K. E. Silicon as a mechanical material. Proc. IEEE 70, 420–457 (1982).10.1109/PROC.1982.12331 ↗
27. Cheng, L. et al. A flexible pressure sensor based on silicon nanomembrane. Biosensors 13, 131 (2023).10.3390/bios13010131 ↗
28. Salvatore, G. A. et al. Wafer-scale design of lightweight and transparent electronics that wraps around hairs. Nat. Commun. 5, 2982 (2014).10.1038/ncomms3982 ↗
29. Yang, X. et al. Ultrathin, stretchable, and breathable epidermal electronics based on a facile bubble blowing method. Adv. Elect. Mater. 6, 2000306 (2020).10.1002/aelm.202000306 ↗
30. Fukuda, K. et al. Fully-printed high-performance organic thin-film transistors and circuitry on one-micron-thick polymer films. Nat. Commun. 5, 4147 (2014).10.1038/ncomms5147 ↗
31. Yang, M. et al. High-performance flexible pressure sensor with a self-healing function for tactile feedback. Adv. Sci. 9, 2200507 (2022).10.1002/advs.202200507 ↗
32. Say, M. G. et al. Ultrathin paper microsupercapacitors for electronic skin applications. Adv. Mater. Technol. 7, 2101420 (2022).10.1002/admt.202101420 ↗
33. Zhang, H. et al. High-performance carbon nanotube complementary electronics and integrated sensor systems on ultrathin plastic foil. ACS Nano 12, 2773–2779 (2018).10.1021/acsnano.7b09145 ↗
34. Lee, S. et al. A transparent bending-insensitive pressure sensor. Nat. Nanotechnol. 11, 472–478 (2016).10.1038/nnano.2015.324 ↗
35. Li, S., Liu, X., Li, R. & Su, Y. Shear deformation dominates in the soft adhesive layers of the laminated structure of flexible electronics. Int. J. Solids Struct. 110–111, 305–314 (2017).10.1016/j.ijsolstr.2016.12.006 ↗
36. Takamatsu, S. et al. Plastic-scale-model assembly of ultrathin film MEMS piezoresistive strain sensor with conventional vacuum-suction chip mounter. Sci. Rep. 9, 1893 (2019).10.1038/s41598-019-39364-2 ↗
37. Takakuwa, M. et al. Direct gold bonding for flexible integrated electronics. Sci. Adv. 7, eabl6228 (2021).10.1126/sciadv.abl6228 ↗
38. Boyd, E. J. & Uttamchandani, D. Measurement of the anisotropy of Young’s modulus in single-crystal silicon. J. Microelectromech. Syst. 21, 243–249 (2012).10.1109/JMEMS.2011.2174415 ↗
39. Hopcroft, M. A., Nix, W. D. & Kenny, T. W. What is the Young’s modulus of silicon?. J. Microelectromech. Syst. 19, 229–238 (2010).10.1109/JMEMS.2009.2039697 ↗
40. Kim, B. J. & Meng, E. Micromachining of parylene C for bioMEMS: micromachining of parylene C for BioMEMS. Polym. Adv. Technol. 27, 564–576 (2016).10.1002/pat.3729 ↗
41. Timoshenko, S. P. & Gere, J. M. Theory of Elastic Stability (McGraw-Hill, 1961).
42. Jones, R. M. Mechanics of Composite Materials (CRC Press, Boca Raton, 2021).
43. Tsuchiya, T. Tensile testing of silicon thin films. Fatigue Fract. Eng. Mat. Struct. 28, 665–674 (2005).10.1111/j.1460-2695.2005.00910.x ↗
44. Ma, R. & Dollar, A. Yale openhand project: optimizing open-source hand designs for ease of fabrication and adoption. IEEE Robot. Autom. Mag. 24, 32–40 (2017).10.1109/MRA.2016.2639034 ↗