Giant magnetoelastic effect in soft systems for bioelectronics

Micromagnets dispersed in a polymer matrix are used to realize a soft magnetoelastic generator with high magnetomechanical coupling factor, used for wearable and implantable power generation and sensing applications. 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.

Automated summary

The study found that dispersing micromagnets in a silicone matrix can achieve a highly efficient soft magnetoelastic generator, with a higher magnetomechanical coupling factor than rigid materials. This new type of flexible magnetic material can be used for stretchable, water-resistant magnetoelastic generators that can conform to human skin, opening up a new avenue for human-body-centered applications.