A programmable magnetoelastic sensor array for self-powered human–machine interface

Skin-integrated electronics that directly interact with machines are transforming our ways of life toward the emerging trend of the metaverse. Consequently, developing a wearable and skin-conformal interface that simultaneously features waterproofness, low cost, and low power consumption for human–machine interaction remains highly desired. Herein, a stretchable, inexpensive, and waterproof magnetoelastic sensor array has been developed as a secondary skin for self-powered human–machine interaction. The magnetoelastic sensor array utilizes the giant magnetoelastic effect in a soft system, which converts mechanical pressure to magnetic field variation and, when coupled with the magnetic induction, can generate electricity. In such a way, our magnetoelastic sensor array comprises the giant magnetomechanical coupling layer made up of nanomagnets and a porous silicone rubber matrix, and the magnetic induction layer, which are coils patterned by liquid metal. With programmable functionalities, the soft magnetoelastic sensor array can supply different commands by producing bespoke electric signals from human finger touch with an optimal signal-to-noise ratio of 34 dB and a rapid response time of 0.2s. To pursue a practical application, the soft magnetoelastic sensor array can wirelessly turn on and off a household lamp and control a music speaker via Bluetooth continuously in real time, even with contact with high-humidity environments such as heavy perspiration. With a collection of compelling features, the soft magnetoelastic sensor array puts forth a unique and savvy avenue of self-powered bioelectronic technology that practically enables a wider variety of applications for wearable human–machine interaction.