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A self-healing electrically conductive organogel composite

Nature Electronics volume 6, pages 206–215 (2023)Cite this article

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Abstract

Self-healing hydrogels use spontaneous intermolecular forces to recover from physical damage caused by extreme strain, pressure or tearing. Such materials are of potential use in soft robotics and tissue engineering, but they have relatively low electrical conductivity, which limits their application in stretchable and mechanically robust circuits. Here we report an organogel composite that is based on poly(vinyl alcohol)–sodium borate and has high electrical conductivity (7 × 104 S m−1), low stiffness (Young’s modulus of ~20 kPa), high stretchability (strain limit of >400%) and spontaneous mechanical and electrical self-healing. The organogel matrix is embedded with silver microflakes and gallium-based liquid metal microdroplets, which form a percolating network, leading to high electrical conductivity in the material. We also overcome the rapid drying problem of the hydrogel material system by replacing water with an organic solvent (ethylene glycol), which avoids dehydration and property changes for over 24 h in an ambient environment. We illustrate the capabilities of the self-healing organogel composite by using it in a soft robot, a soft circuit and a reconfigurable bioelectrode.

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Fig. 1: Self-healing, electrically conductive organogel.
Fig. 2: Mechanical, electrical and self-healing properties.
Fig. 3: Self-healing and reconfigurable Ag–LM–PVA composite for robust motor circuitry and EMG electrodes.

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Data availability

The data that support the plots within this paper are available from the corresponding author upon reasonable request.

Code availability

The customized tracking algorithm and EMG sensing data-processing code used in this work are available at https://drive.google.com/drive/folders/1DG0Ev9oP3RWoiptVC6TepfWJDQI7y235?usp=sharing.

References

  1. Terryn, S. et al. A review on self-healing polymers for soft robotics. Mater. Today 47, 187–205 (2021).

    Article  Google Scholar 

  2. Bartlett, M. D., Dickey, M. D. & Majidi, C. Self-healing materials for soft-matter machines and electronics. NPG Asia Mater. 11, 21 (2019).

    Article  Google Scholar 

  3. Chen, J., Huang, Y., Ma, X. & Lei, Y. Functional self-healing materials and their potential applications in biomedical engineering. Adv. Compos. Hybrid. Mater. 1, 94–113 (2018).

    Article  Google Scholar 

  4. Idumah, C. I., Nwuzor, I. & Odera, S. R. Recent advancements in self-healing polymeric hydrogels, shape memory and stretchable materials. Int. J. Polymeric Mater. Polymeric Biomater. 70, 941–966 (2021).

    Article  Google Scholar 

  5. Kanu, N. J., Gupta, E., Vates, U. K. & Singh, G. K. Self-healing composites: a state-of-the-art review. Compos. A Appl. Sci. Manuf. 121, 474–486 (2019).

    Article  Google Scholar 

  6. Cao, Y. et al. Self-healing electronic skins for aquatic environments. Nat. Electron. 2, 75–82 (2019).

    Article  Google Scholar 

  7. Yu, X. et al. Highly stretchable, ultra-soft and fast self-healable conductive hydrogels based on polyaniline nanoparticles for sensitive flexible sensors. Adv. Funct. Mater. 32, 2204366 (2022).

    Article  Google Scholar 

  8. Hao, X. P. et al. Healable, recyclable and multifunctional soft electronics based on biopolymer hydrogel and patterned liquid metal. Small 18, 2201643 (2022).

    Article  Google Scholar 

  9. Deng, Z., Wang, H., Ma, P. X. & Guo, B. Self-healing conductive hydrogels: preparation, properties and applications. Nanoscale 12, 1224–1246 (2020).

    Article  Google Scholar 

  10. Zhang, A. et al. Research status of selfhealing hydrogel for wound management: a review. Int. J. Biol. Macromol. 164, 2108–2123 (2020).

    Article  Google Scholar 

  11. Zhang, Z. et al. Highly transparent, self-healable and adhesive organogels for bio-inspired intelligent ionic skins. ACS Appl. Mater. Interfaces 12, 15657–15666 (2020).

    Article  Google Scholar 

  12. Polachan, K., Chatterjee, B., Weigand, S. & Sen, S. Human body-electrode interfaces for wide-frequency sensing and communication: a review. Nanomaterials 11, 2152 (2021).

    Article  Google Scholar 

  13. Zhang, X. et al. Supramolecular nanofibrillar hydrogels as highly stretchable, elastic and sensitive ionic sensors. Mater. Horiz. 6, 326–333 (2019).

    Article  Google Scholar 

  14. Liu, K. et al. Ultrasoft self-healing nanoparticle-hydrogel composites with conductive and magnetic properties. ACS Sustain. Chem. Eng. 6, 6395–6403 (2018).

    Article  Google Scholar 

  15. Lim, C. et al. Stretchable conductive nanocomposite based on alginate hydrogel and silver nanowires for wearable electronics. APL Mater. 7, 031502 (2018).

    Article  Google Scholar 

  16. Zhao, W. et al. 3D printing of stretchable, adhesive and conductive Ti3C2Tx-polyacrylic acid hydrogels. Polymers 14, 1992 (2022).

    Article  Google Scholar 

  17. Zhang, L. & Shi, G. Preparation of highly conductive graphene hydrogels for fabricating supercapacitors with high rate capability. J. Phys. Chem. C 115, 17206–17212 (2011).

    Article  Google Scholar 

  18. Li, P. et al. Stretchable all-gel-state fiber-shaped supercapacitors enabled by macromolecularly interconnected 3D graphene/nanostructured conductive polymer hydrogels. Adv. Mater. 30, 1800124 (2018).

    Article  Google Scholar 

  19. Deng, Z. et al. Stimuli-responsive conductive nanocomposite hydrogels with high stretchability, self-healing, adhesiveness, and 3D printability for human motion sensing. ACS Appl. Mater. Interfaces 11, 6796–6808 (2019).

    Article  Google Scholar 

  20. Dai, S., Zhou, X., Wang, S., Ding, J. & Yuan, N. A self-healing conductive and stretchable aligned carbon nanotube/hydrogel composite with a sandwich structure. Nanoscale 10, 19360–19366 (2018).

    Article  Google Scholar 

  21. Yang, W. et al. Robust and mechanically and electrically self-healing hydrogel for efficient electromagnetic interference shielding. ACS Appl. Mater. Interfaces 10, 8245–8257 (2018).

    Article  Google Scholar 

  22. Chen, J., Peng, Q., Thundat, T. & Zeng, H. Stretchable, injectable and self-healing conductive hydrogel enabled by multiple hydrogen bonding toward wearable electronics. Chem. Mater. 31, 4553–4563 (2019).

    Article  Google Scholar 

  23. Dispenza, C. et al. Electrically conductive hydrogel composites made of polyaniline nanoparticles and poly(N-vinyl-2-pyrrolidone). Polymer 47, 961–971 (2006).

    Article  Google Scholar 

  24. Yang, Q., Hu, Z. & Rogers, J. A. Functional hydrogel interface materials for advanced bioelectronic devices. Acc. Mater. Res. 2, 1010–1023 (2021).

    Article  Google Scholar 

  25. Cai, S. et al. Soft liquid metal infused conductive sponges. Adv. Mater. Technol. 7, 2101500 (2022).

    Article  Google Scholar 

  26. Ohm, Y. et al. An electrically conductive silver–polyacrylamide–alginate hydrogel composite for soft electronics. Nat. Electron. 4, 185–192 (2021).

    Article  Google Scholar 

  27. Fassler, A. & Majidi, C. Liquid-phase metal inclusions for a conductive polymer composite. Adv. Mater. 27, 1928–1932 (2015).

    Article  Google Scholar 

  28. Majidi, C., Alizadeh, K., Ohm, Y., Silva, A. & Tavakoli, M. Liquid metal polymer composites: from printed stretchable circuits to soft actuators. Flex. Print. Electron. 7, 013002 (2022).

    Article  Google Scholar 

  29. Tang, S.-Y., Tabor, C., Kalantar-Zadeh, K. & Dickey, M. D. Gallium liquid metal: the devil’s elixir. Annu. Rev. Mater. Res. 51, 381–408 (2021).

    Article  Google Scholar 

  30. Park, J.-E. et al. Rewritable, printable conducting liquid metal hydrogel. ACS Nano 13, 9122–9130 (2019).

    Article  Google Scholar 

  31. Liao, M., Liao, H., Ye, J., Wan, P. & Zhang, L. Polyvinyl alcohol-stabilized liquid metal hydrogel for wearable transient epidermal sensors. ACS Appl. Mater. Interfaces 11, 47358–47364 (2019).

    Article  Google Scholar 

  32. Ford, M. J. et al. Controlled assembly of liquid metal inclusions as a general approach for multifunctional composites. Adv. Mater. 32, 2002929 (2020).

    Article  Google Scholar 

  33. Chen, Y. et al. A gradient-distributed liquid-metal hydrogel capable of tunable actuation. Chem. Eng. J. 421, 127762 (2021).

    Article  Google Scholar 

  34. Xu, J. et al. Polymerization of moldable self-healing hydrogel with liquid metal nanodroplets for flexible strain-sensing devices. Chem. Eng. J. 392, 123788 (2020).

    Article  Google Scholar 

  35. Peng, H., Xin, Y., Xu, J., Liu, H. & Zhang, J. Ultra-stretchable hydrogels with reactive liquid metals as asymmetric force-sensors. Mater. Horiz. 6, 618–625 (2019).

    Article  Google Scholar 

  36. Xu, Y. et al. Convergent synthesis of diversified reversible network leads to liquid metal-containing conductive hydrogel adhesives. Nat. Commun. 12, 2407 (2021).

    Article  Google Scholar 

  37. Spoljaric, S., Salminen, A., Luong, N. D. & Seppälä, J. Stable, self-healing hydrogels from nanofibrillated cellulose, poly(vinyl alcohol) and borax via reversible crosslinking. Eur. Polym. J. 56, 105–117 (2014).

    Article  Google Scholar 

  38. Hassan, C. M. & Peppas, N. A. Structure and morphology of freeze/thawed PVA hydrogels. Macromolecules 33, 2472–2479 (2000).

    Article  Google Scholar 

  39. Hung, W.-L., Wang, D.-M., Lai, J.-Y. & Chou, S.-C. On the initiation of macrovoids in polymeric membranes—effect of polymer chain entanglement. J. Membr. Sci. 505, 70–81 (2016).

    Article  Google Scholar 

  40. Bercea, M., Morariu, S. & Rusu, D. In situ gelation of aqueous solutions of entangled poly(vinyl alcohol). Soft Matter 9, 1244–1253 (2013).

    Article  Google Scholar 

  41. Rusdi, M., Moroi, Y., Nakahara, H. & Shibata, O. Evaporation from water-ethylene glycol liquid mixture. Langmuir 21, 7308–7310 (2005).

    Article  Google Scholar 

  42. Chen, H., Ren, X. & Gao, G. Skin-inspired gels with toughness, antifreezing, conductivity and remoldability. ACS Appl. Mater. Interfaces 11, 28336–28344 (2019).

    Article  Google Scholar 

  43. Rong, Q. et al. Anti-freezing, conductive self-healing organohydrogels with stable strain-sensitivity at subzero temperatures. Angew. Chem. Int. Ed. 56, 14159–14163 (2017).

    Article  MathSciNet  Google Scholar 

  44. Dillon, P. F. Biophysics: A Physiological Approach (Cambridge Univ. Press, 2012).

  45. .Samal, S. Effect of shape and size of filler particle on the aggregation and sedimentation behavior of the polymer composite. Powder Technol. 366, 43–51 (2020).

    Article  Google Scholar 

  46. Wang, J. et al. Printable superelastic conductors with extreme stretchability and robust cycling endurance enabled by liquid-metal particles. Adv. Mater. 30, 1706157 (2018).

    Article  Google Scholar 

  47. Hajalilou, A. et al. Biphasic liquid metal composites for sinter-free printed stretchable electronics. Adv. Mater. Interfaces 9, 2101913 (2022).

    Article  Google Scholar 

  48. Zu, W. et al. A comparative study of silver microflakes in digitally printable liquid metal embedded elastomer inks for stretchable electronics. Adv. Mater. Technol. 7, 2200534 (2022).

    Article  Google Scholar 

  49. Lynne Taylor, D. & Panhuis, Minhet Self-healing hydrogels. Adv. Mater. 28, 90609093 (2016).

    Google Scholar 

Download references

Acknowledgements

This work was partially funded by the Air Force Research Lab (AFRL) through the National Bio Materials Consortium (NBMC) under grant no. NB18-21-33.

Author information

Authors and Affiliations

  1. Soft Machines Lab, Carnegie Mellon University, Pittsburgh, PA, USA

    Yongyi Zhao, Yunsik Ohm, Jiahe Liao, Yichi Luo, Phillip Won, Peter Roberts & Carmel Majidi

  2. Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA, USA

    Yongyi Zhao, Yunsik Ohm, Yichi Luo, Phillip Won, Peter Roberts, Manuel Reis Carneiro & Carmel Majidi

  3. Robotics Institute, Carnegie Mellon University, Pittsburgh, PA, USA

    Jiahe Liao & Carmel Majidi

  4. Materials Science & Engineering, Carnegie Mellon University, Pittsburgh, PA, USA

    Huai-Yu Cheng, Mohammad F. Islam & Carmel Majidi

  5. Institute of Systems and Robotics, Department of Electrical and Computer Engineering, University of Coimbra, Coimbra, Portugal

    Manuel Reis Carneiro & Jung Hyun Ahn

  6. Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA, USA

    Lynn M. Walker

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Contributions

Y.Z., Y.O. and C.M. designed the research. Y.Z. and Y.O. fabricated the materials. Y.Z., H.-Y.C., M.R.C., P.W. and J.H.A. performed the experiments. Y.Z., J.L., M.R.C. and C.M. analysed the data. Y.Z. and J.L. produced the demonstration of the snail-inspired crawling robot. Y.Z. and Y.L. fabricated the soft reconfigurable circuitry. Y.Z. and Y.L. demonstrated the EMG sensing electrodes. Y.Z., Y.O., J.L., P.W., P.R., M.F.I., L.M.W. and C.M. wrote the paper.

Corresponding author

Correspondence to Carmel Majidi.

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Nature Electronics thanks Michael Dickey and Guanghui Gao for their contribution to the peer review of this work.

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Zhao, Y., Ohm, Y., Liao, J. et al. A self-healing electrically conductive organogel composite. Nat Electron 6, 206–215 (2023). https://doi.org/10.1038/s41928-023-00932-0

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