Highly Flexible, Adhesive, Antimicrobial, and Self-Powered Hydrogel Strain Sensor for Human Motion Monitoring

Piezoelectric hydrogel sensors are a recent innovation that combines the flexibility of hydrogels with the self-powering of piezoelectric materials. Here, we present a self-powered hydrogel strain sensor by incorporating piezoelectric Na₀.₅Bi₀.₅TiO₃ nanoparticles into a dual-network hydrogel composed of poly(vinyl alcohol), acrylamide, and 2-acrylamido-2-methyl-1-propanesulfonic acid. The hydrogel exhibits excellent mechanical properties, achieving a tensile strength of 1.28 MPa, an elongation at break of 1127%, and strong tissue adhesion (55.97 kPa on porcine skin). The sensor delivers a maximum output voltage of 237.4 mV, a sensitivity of 17.99 mV under small compressive strain, and a broad tensile strain detection range of 30 to 400%. It reliably monitors both subtle physiological activities (facial expression, swallowing, pulse) and large joint movements. Moreover, it exhibits notable antibacterial performance via ultrasound-driven piezocatalysis, reducing bacterial viability to below 1.5%. This tough, adhesive, and antibacterial piezoelectric hydrogel sensor holds significant promise for wearable electronics and human-machine interfaces.