Self-powered physiological monitoring strategy enabled by adaptive dual-network thermogalvanic hydrogels

The development of wearable epidermal electronics has revolutionized the way vital signs are collected and monitored. However, they require a continuous power supply from an external source, which greatly limits their practical application. Excitingly, flexible thermogalvanic gels can convert human waste heat into electricity, which in turn can be used as a stretchable miniature passive electronic device that is of great importance in cutting-edge wearable healthcare. We have manufactured a conformal thermogalvanic generator with Fe2+/Fe3+ electrolyte-based hydrogel and MWCNT (Multi-walled Carbon Nanotubes)-based electrodes, which presents not only outstanding thermoelectric performance but also perfect flexibility and stretchability. Simultaneously packaged with the integrated thermogalvanic gel and flexible electrodes, which is particularly suitable as a wearable epidermal patch. Given the excellent temperature response of the thermogalvanic gel, we have fabricated a self-powered body temperature monitoring patch that could be conformally attached on the wrist or other points. Meanwhile, the gel patch possesses high responsivity on strain that can recognize the pulse beat at the wrist. This work sheds fresh light on the developing self-powered wearable epidermal healthcare electronics by converting low-grade human body heat.