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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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.
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.
Peer review information Nature Materials thanks the anonymous reviewers for their contribution to the peer review of this work.
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Zhou, Y., Zhao, X., Xu, J. et al. Giant magnetoelastic effect in soft systems for bioelectronics. Nat. Mater. (2021). https://doi.org/10.1038/s41563-021-01093-1