Abstract
The magnetoelastic effect—the variation of the magnetic properties of a material under mechanical stress—is usually observed in rigid alloys, whose mechanical modulus is significantly different from that of human tissues, thus limiting their use in bioelectronics applications. Here, we observed a giant magnetoelastic effect in a soft system based on micromagnets dispersed in a silicone matrix, reaching a magnetomechanical coupling factor indicating up to four times more enhancement than in rigid counterparts. The results are interpreted using a wavy chain model, showing how mechanical stress changes the micromagnets’ spacing and dipole alignment, thus altering the magnetic field generated by the composite. Combined with liquid-metal coils patterned on polydimethylsiloxane working as a magnetic induction layer, the soft magnetoelastic composite is used for stretchable and water-resistant magnetoelastic generators adhering conformably to human skin. Such devices can be used as wearable or implantable power generators and biomedical sensors, opening alternative avenues for human-body-centred applications.
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Data availability
Source data are provided with this paper. Other data generated or analysed during this study are included in the Supplementary Information. Further data are available from the corresponding author upon request.
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Acknowledgements
We acknowledge the Henry Samueli School of Engineering and Applied Science and the Department of Bioengineering at the University of California, Los Angeles for the start-up support. J.C. also acknowledges the 2020 Okawa Foundation Research Grant and the 2021 Hellman Fellows Fund.
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Contributions
J.C. conceived the idea and guided the whole project. Y.Z., X.Z. and J.C. designed the experiment, analysed the data, drew the figures and composed the manuscript. J.X. contributed to the design of the integrated cardiovascular health monitoring system; Y.F. and G.C. contributed to the modelling analysis and made technical comments on the manuscript. Y.S., X.Z. and S.L. contributed to the biocompatibility test of the soft MEGs. All authors have seen the paper, agree to its content and approve the submission.
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A patent has been filed related to this work from the University of California, Los Angeles with US provisional patent application no. 63/176,651.
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Supplementary Information
Supplementary Figs. 1–50, Tables 1–3 and Notes 1–7.
Supplementary Video 1
The three-dimensional tomography of the giant magnetomechanical coupling layer.
Supplementary Video 2
Wirelessly measuring human pulse wave in a sweaty state.
Source data
Source Data Fig. 1
Source data for Fig. 1d–i.
Source Data Fig. 2
Source data for Fig. 2c–h.
Source Data Fig. 3
Source data for Fig. 3b–h,j.
Source Data Fig. 4
Source data for Fig. 4c,d.
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Zhou, Y., Zhao, X., Xu, J. et al. Giant magnetoelastic effect in soft systems for bioelectronics. Nat. Mater. 20, 1670–1676 (2021). https://doi.org/10.1038/s41563-021-01093-1
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DOI: https://doi.org/10.1038/s41563-021-01093-1
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