A Fully Biodegradable and Biocompatible Ionotronic Skin for Transient Electronics

Abstract Wearable electronics have impacted many aspects of human life including health monitoring, disease diagnosis, and human‐machine interfacing. However, the rapid development also accelerates the generation of electronic waste (e‐waste), which is threatening the health of ecological systems. Accordingly, high‐performance biodegradable materials suitable for transient electronics are highly demanded and challenging. In this work, a fully biodegradable and biocompatible ionotronic skin is designed based on double‐network natural polyelectrolytes derivatives. It consists of carboxylated chitosan (CCS) and sulfobetaine methacrylate (SBMA) polymerized in glycerol and water followed by cross‐linking with hydrogen bonds and electrostatic attraction (namely SBMA X ‐CCS Y ‐Gly z ). By macromolecular engineering, the ionotronic skin exhibits high ionic conductivity, good compliance with skin, as well as complete degradability, which is capable of transient measurement of electrophysiology. Applied on the sciatic nerve of bullfrog, it can accurately record action potentials and fully degrade in only 3 days without any residue. Such biodegradable and biocompatible ionotronic skin will shed light on the design of ionotronic materials for future transient electronics.