Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Article
  • Published:

Creep-free polyelectrolyte elastomer for drift-free iontronic sensing

Nature Materials (2024)Cite this article

Subjects

Abstract

Artificial pressure sensors often use soft materials to achieve skin-like softness, but the viscoelastic creep of soft materials and the ion leakage, specifically for ionic conductors, cause signal drift and inaccurate measurement. Here we report drift-free iontronic sensing by designing and copolymerizing a leakage-free and creep-free polyelectrolyte elastomer containing two types of segments: charged segments having fixed cations to prevent ion leakage and neutral slippery segments with a high crosslink density for low creep. We show that an iontronic sensor using the polyelectrolyte elastomer barely drifts under an ultrahigh static pressure of 500 kPa (close to its Young’s modulus), exhibits a drift rate two to three orders of magnitude lower than that of the sensors adopting conventional ionic conductors and enables steady and accurate control for robotic manipulation. Such drift-free iontronic sensing represents a step towards highly accurate sensing in robotics and beyond.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Fig. 1: Principles, materials and chemistries for drift-free iontronic sensing.
Fig. 2: Characterizations of the polyelectrolyte elastomer.
Fig. 3: Sensing properties of the iontronic sensor.
Fig. 4: Drift ratio and drift rate of various iontronic sensors.
Fig. 5: Accurate force sensing for steady robotic manipulation.

Similar content being viewed by others

Data availability

The data that support the findings of this study are available at https://doi.org/10.6084/m9.figshare.25266307.

References

  1. Luh, J., Fisher, W. & Paul, R. Joint torque control by a direct feedback for industrial robots. IEEE Trans. Autom. Control 28, 153–161 (1983).

    Google Scholar 

  2. Cheng, G. et al. A comprehensive realization of robot skin: sensors, sensing, control, and applications. Proc. IEEE 107, 2034–2051 (2019).

    Google Scholar 

  3. Dahiya, R. E-Skin: from humanoids to humans (point of view). Proc. IEEE 107, 247–252 (2019).

    Google Scholar 

  4. Cho, A., Kim, J., Lee, S. & Kee, C. Wind estimation and airspeed calibration using a UAV with a single-antenna GPS receiver and pitot tube. IEEE Trans. Aerosp. Electron. Syst. 47, 109–117 (2011).

    Google Scholar 

  5. Xu, Z. et al. Digital mapping of surface turbulence status and aerodynamic stall on wings of a flying aircraft. Nat. Commun. 14, 2792 (2023).

    CAS  PubMed  PubMed Central  Google Scholar 

  6. Yang, S. et al. A survey of intelligent tires for tire-road interaction recognition toward autonomous vehicles. IEEE Trans. Intell. Veh. 7, 520–532 (2022).

    Google Scholar 

  7. Liu, Y. et al. Electronic skin as wireless human–machine interfaces for robotic VR. Sci. Adv. 8, eabl6700 (2022).

    PubMed  PubMed Central  Google Scholar 

  8. Zhu, M. L. et al. Haptic-feedback smart glove as a creative human–machine interface (HMI) for virtual/augmented reality applications. Sci. Adv. 6, eaaz8693 (2020).

    CAS  PubMed  PubMed Central  Google Scholar 

  9. Sun, Z., Zhu, M., Shan, X. & Lee, C. Augmented tactile-perception and haptic-feedback rings as human–machine interfaces aiming for immersive interactions. Nat. Commun. 13, 5224 (2022).

    CAS  PubMed  PubMed Central  Google Scholar 

  10. Chortos, A., Liu, J. & Bao, Z. Pursuing prosthetic electronic skin. Nat. Mater. 15, 937–950 (2016).

    CAS  PubMed  Google Scholar 

  11. Kang, S.-K. et al. Bioresorbable silicon electronic sensors for the brain. Nature 530, 71–76 (2016).

    CAS  PubMed  Google Scholar 

  12. Wang, L. et al. A review of wearable sensor systems to monitor plantar loading in the assessment of diabetic foot ulcers. IEEE Trans. Biomed. Eng. 67, 1989–2004 (2020).

    PubMed  Google Scholar 

  13. Su, Q. et al. A stretchable and strain-unperturbed pressure sensor for motion interference-free tactile monitoring on skins. Sci. Adv. 7, eabi4563 (2021).

    PubMed  PubMed Central  Google Scholar 

  14. Lee, S. et al. Nanomesh pressure sensor for monitoring finger manipulation without sensory interference. Science 370, 966–970 (2020).

    CAS  PubMed  Google Scholar 

  15. Boutry, C. M. et al. A stretchable and biodegradable strain and pressure sensor for orthopaedic application. Nat. Electron. 1, 314–321 (2018).

    Google Scholar 

  16. Yang, C. & Suo, Z. Hydrogel ionotronics. Nat. Rev. Mater. 3, 125–142 (2018).

    Google Scholar 

  17. Chang, Y. et al. First decade of interfacial iontronic sensing: from droplet sensors to artificial skins. Adv. Mater. 33, 2003464 (2021).

    CAS  Google Scholar 

  18. Lee, H. R., Kim, C. C. & Sun, J. Y. Stretchable ionics—a promising candidate for upcoming wearable devices. Adv. Mater. 30, 1704403 (2018).

    Google Scholar 

  19. Yuan, Y. et al. Microstructured polyelectrolyte elastomer-based ionotronic sensors with high sensitivities and excellent stability for artificial skins. Adv. Mater. https://doi.org/10.1002/adma.202310429 (2023).

  20. Sun, T. L. et al. Physical hydrogels composed of polyampholytes demonstrate high toughness and viscoelasticity. Nat. Mater. 12, 932–937 (2013).

    CAS  PubMed  Google Scholar 

  21. Leocmach, M., Perge, C., Divoux, T. & Manneville, S. Creep and fracture of a protein gel under stress. Phys. Rev. Lett. 113, 038303 (2014).

    CAS  PubMed  Google Scholar 

  22. Rubinstein, M. & Colby, R. H. Polymer Physics (Oxford Univ., 2003).

    Google Scholar 

  23. Biot, M. A. General theory of three‐dimensional consolidation. J. Appl. Phys. 12, 155–164 (1941).

    Google Scholar 

  24. Zhu, J. & Liu, Q. The osmocapillary effect on a rough gel surface. J. Mech. Phys. Solids 170, 105124 (2023).

    Google Scholar 

  25. Karobi, S. N. et al. Creep behavior and delayed fracture of tough polyampholyte hydrogels by tensile test. Macromolecules 49, 5630–5636 (2016).

    CAS  Google Scholar 

  26. Zhou, Y. et al. The stiffness-threshold conflict in polymer networks and a resolution. J. Appl. Mech. 87, 031002 (2020).

    CAS  Google Scholar 

  27. Choi, J.-H., Xie, W., Gu, Y., Frisbie, C. D. & Lodge, T. P. Single ion conducting, polymerized ionic liquid triblock copolymer films: high capacitance electrolyte gates for n-type transistors. ACS Appl. Mater. Interfaces 7, 7294–7302 (2015).

    CAS  PubMed  Google Scholar 

  28. Kim, H. J., Chen, B., Suo, Z. & Hayward, R. C. Ionoelastomer junctions between polymer networks of fixed anions and cations. Science 367, 773–776 (2020).

    CAS  PubMed  Google Scholar 

  29. Fan, F. et al. Effect of molecular weight on the ion transport mechanism in polymerized ionic liquids. Macromolecules 49, 4557–4570 (2016).

    CAS  Google Scholar 

  30. Yang, R. et al. Iontronic pressure sensor with high sensitivity over ultra-broad linear range enabled by laser-induced gradient micro-pyramids. Nat. Commun. 14, 2907 (2023).

    CAS  PubMed  PubMed Central  Google Scholar 

  31. Bai, N. et al. Graded intrafillable architecture-based iontronic pressure sensor with ultra-broad-range high sensitivity. Nat. Commun. 11, 209 (2020).

    CAS  PubMed  PubMed Central  Google Scholar 

  32. Zhang, Y. et al. Highly stable flexible pressure sensors with a quasi-homogeneous composition and interlinked interfaces. Nat. Commun. 13, 1317 (2022).

    CAS  PubMed  PubMed Central  Google Scholar 

  33. Mannsfeld, S. C. B. et al. Highly sensitive flexible pressure sensors with microstructured rubber dielectric layers. Nat. Mater. 9, 859–864 (2010).

    CAS  PubMed  Google Scholar 

  34. Yiming, B. et al. A mechanically robust and versatile liquid‐free ionic conductive elastomer. Adv. Mater. 33, 2006111 (2021).

    CAS  Google Scholar 

  35. Nie, B., Li, R., Cao, J., Brandt, J. D. & Pan, T. Flexible transparent iontronic film for interfacial capacitive pressure sensing. Adv. Mater. 27, 6055–6062 (2015).

    CAS  PubMed  Google Scholar 

  36. Cui, X. et al. Flexible and breathable all-nanofiber iontronic pressure sensors with ultraviolet shielding and antibacterial performances for wearable electronics. Nano Energy 95, 107022 (2022).

    CAS  Google Scholar 

  37. Yu, X. et al. Ultra-tough waterborne polyurethane-based graft-copolymerized piezoresistive composite designed for rehabilitation training monitoring pressure sensors. Small 19, 2303095 (2023).

    CAS  Google Scholar 

  38. Bai, N. et al. Graded interlocks for iontronic pressure sensors with high sensitivity and high linearity over a broad range. ACS Nano. 16, 4338–4347 (2022).

    CAS  PubMed  Google Scholar 

  39. Li, P. et al. Skin-inspired large area iontronic pressure sensor with ultra-broad range and high sensitivity. Nano Energy 101, 107571 (2022).

    CAS  Google Scholar 

  40. Shi, J. et al. Embedment of sensing elements for robust, highly sensitive, and cross-talk–free iontronic skins for robotics applications. Sci. Adv. 9, eadf8831 (2023).

    CAS  PubMed  PubMed Central  Google Scholar 

  41. Terabe, H. et al. in Proc. International Solid State Sensors and Actuators Conference (Transducers’ 97) Vol. 2 1481–1484 (IEEE, 1997).

  42. Lu, P. et al. Iontronic pressure sensor with high sensitivity and linear response over a wide pressure range based on soft micropillared electrodes. Sci. Bull. 66, 1091–1100 (2021).

    Google Scholar 

  43. Chen, X. et al. Channel-crack-designed suspended sensing membrane as a fully flexible vibration sensor with high sensitivity and dynamic range. ACS Appl. Mater. Interfaces 13, 34637–34647 (2021).

    CAS  PubMed  Google Scholar 

  44. Ha, K.-H. et al. Highly sensitive capacitive pressure sensors over a wide pressure range enabled by the hybrid responses of a highly porous nanocomposite. Adv. Mater. 33, 2103320 (2021).

    CAS  Google Scholar 

  45. Docherty, K. M. & Kulpa, C. F. Jr Toxicity and antimicrobial activity of imidazolium and pyridinium ionic liquids. Green. Chem. 7, 185–189 (2005).

    CAS  Google Scholar 

  46. Rivlin, R. & Thomas, A. G. Rupture of rubber. I. Characteristic energy for tearing. J. Polym. Sci. 10, 291–318 (1953).

    CAS  Google Scholar 

Download references

Acknowledgements

The work is supported by National Key Research and Development Program of China (grants 2023YFB3812500), the National Natural Science Foundation of China (nos. T2225017, 12302212 and 52073138), the Science, Technology, and Innovation Commission of Shenzhen Municipality (ZDSYS20210623092005017), the Science Technology and Innovation Committee of Shenzhen Municipality (no. JCYJ20220530114810024), the Shenzhen Sci-Tech Fund (no. YTDPT20181011104007) and the Guangdong Provincial Key Laboratory Program (no. 2021B1212040001). The authors acknowledge the assistance of SUSTech Core Research Facilities.

Author information

Author notes

  1. These authors contributed equally: Yunfeng He, Yu Cheng.

Authors and Affiliations

  1. Shenzhen Key Laboratory of Soft Mechanics and Smart Manufacturing, Department of Mechanics and Aerospace Engineering, Southern University of Science and Technology, Shenzhen, P. R. China

    Yunfeng He & Canhui Yang

  2. Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen, P. R. China

    Yu Cheng & Chuan Fei Guo

Authors
  1. Yunfeng He
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Yu Cheng
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Canhui Yang
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Chuan Fei Guo
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

C.Y. and C.F.G. conceived the idea and designed the research. Y.H. designed, synthesized and characterized the polyelectrolyte elastomer. Y.C. designed, fabricated and characterized the drift-free iontronic sensor. Y.H. designed and performed the closed-loop robotic manipulation. C.Y. and C.F.G. drafted the manuscript. All authors discussed the results and commented on the manuscript.

Corresponding authors

Correspondence to Canhui Yang or Chuan Fei Guo.

Ethics declarations

Competing interests

The authors declare no competing interests.

Peer review

Peer review information

Nature Materials thanks Huanyu Cheng and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

Supplementary Notes 1 and 2, Figs. 1–35, Tables 1–4 and descriptions of Movies 1–7.

Reporting Summary

Supplementary Video 1

Clamping of a steel block of the gripper with a PEE-based sensor.

Supplementary Video 2

Clamping of a steel block of the gripper with an ionogel-based sensor.

Supplementary Video 3

Clamping of a cherry tomato of the gripper with a PEE-based sensor.

Supplementary Video 4

Clamping of a cherry tomato of the gripper with an ionogel-based sensor.

Supplementary Video 5

Clamping of a cherry tomato of the gripper with a hydrogel-based sensor.

Supplementary Video 6

Effect of β on creep behaviour.

Supplementary Video 7

Creep behaviours under a high/low pressure/modulus ratio.

Rights and permissions

Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

He, Y., Cheng, Y., Yang, C. et al. Creep-free polyelectrolyte elastomer for drift-free iontronic sensing. Nat. Mater. (2024). https://doi.org/10.1038/s41563-024-01848-6

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI: https://doi.org/10.1038/s41563-024-01848-6

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing