Permeable superelastic liquid-metal fibre mat enables biocompatible and monolithic stretchable electronics

Abstract

Stretchable electronics find widespread uses in a variety of applications such as wearable electronics, on-skin electronics, soft robotics and bioelectronics. Stretchable electronic devices conventionally built with elastomeric thin films show a lack of permeability, which not only impedes wearing comfort and creates skin inflammation over long-term wearing but also limits the design form factors of device integration in the vertical direction. Here, we report a stretchable conductor that is fabricated by simply coating or printing liquid metal onto an electrospun elastomeric fibre mat. We call this stretchable conductor a liquid-metal fibre mat. Liquid metal hanging among the elastomeric fibres self-organizes into a laterally mesh-like and vertically buckled structure, which offers simultaneously high permeability, stretchability, conductivity and electrical stability. Furthermore, the liquid-metal fibre mat shows good biocompatibility and smart adaptiveness to omnidirectional stretching over 1,800% strain. We demonstrate the use of a liquid-metal fibre mat as a building block to realize highly permeable, multifunctional monolithic stretchable electronics.

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Fig. 1: Permeable and superelastic LMFM.
Fig. 2: Mechanism of superelasticity of LMFM.
Fig. 3: Stable and self-adaptive superelasticity of LMFMs.
Fig. 4: Biocompatibility of LMFMs.
Fig. 5: Printing and encapsulation of EGaIn-SBS.
Fig. 6: Monolithic stretchable electronics.

Data availability

The main data supporting the findings of this study are available from the corresponding author upon request. Source data are provided with this paper.

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Acknowledgements

We acknowledge financial support from the Hong Kong Scholars (no. XJ2016051), Research Grants Council of Hong Kong (PolyU 153032/18P), National Natural Science Foundation of China (grant no. 51872095) and Key R&D Program of Guangzhou (no. 202007020003). We also appreciate the valuable discussion on thermal comfort with J. Fan from The Hong Kong Polytechnic University.

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Authors

Contributions

Z.M. and Z.Z. conceived and designed the experiments. Z.M. and Q.X. performed the experiments. Z.M., Q.H. and Q.Z. performed the materials characterization. Z.M. tested the devices’ performances. X.Z., Y.Y., H.Q. and Z.Y. performed the in vivo cell and animal experiments. Z.M. and Q.H. analysed the data. Y.C. and C.W. conducted the numerical model and calculation for the materials. Z.M., Q.H. and Z.Z. wrote the manuscript. Z.Z. supervised the project. All authors discussed the results and commented on the manuscript.

Corresponding author

Correspondence to Zijian Zheng.

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The authors declare no competing interests.

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Peer review information Nature Materials thanks Jaehong Lee, Tsuyoshi Sekitani and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

Supplementary Figs. 1–17 and Tables 1 and 2.

Reporting Summary

Supplementary Video 1

This video shows the washing ability of the EGaIn-SBS mat. During the washing, no leakage of liquid metal was observed, and there was no obvious change in the performance of the LED array.

Supplementary Video 2

This video shows the air permeability of the electrospun SBS mat, EGaIn-SBS mat, multilayer EGaIn-SBS mat, PDMS film and Ecoflex film. The samples were wrapped onto a glass tube, through which air was blown into water.

Source data

Source Data Fig. 1

Statistical source data for Fig. 1e, Fig. 1f and Fig. 1h.

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Source Data Fig. 4

Statistical source data for Fig. 4b and Fig. 4c.

Source Data Fig. 5

Statistical source data for Fig. 5e.

Source Data Fig. 6

Statistical source data for Fig. 6d, Fig. 6e, Fig. 6f and Fig. 6h.

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Ma, Z., Huang, Q., Xu, Q. et al. Permeable superelastic liquid-metal fibre mat enables biocompatible and monolithic stretchable electronics. Nat. Mater. (2021). https://doi.org/10.1038/s41563-020-00902-3

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