Liquid metal-polymer conductor-based wireless, battery-free epidermal patch.

Wearable epidermal patch can seamlessly monitor biological signals in real-time. Here, we report a liquid metal-polymer conductor-based wireless epidermal patch. The epidermal patch is made of a new conductive material called liquid metal-polymer conductors (LMPC). LMPC is made by casting and peeling off polymers from patterned liquid metal particles. Our printable conductors present good stretchability, repeatability, and biocompatibility. We fabricate LMPC-based antenna and wire, which achieves wireless signal communication and power supply. To demonstrate the capability of our LMPC-based antenna and wire, we fabricate an epidermal patch to analyze metabolites, electrolytes, and urea in sweat. When a portable device is close to the epidermal sensor, the device can power and read the sensor through LMPC-based antenna. The epidermal patch exhibited good analytical performance for sweat analysis with a low limit of detection, fast response time, and multiplex detection capabilities. This epidermal patch opens the possibility for a broad range of non-invasive diagnostic tools that can be used for health monitoring in the general population.