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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.

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.

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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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