Self-wrinkled Chitosan and Polyacrylic Acid-based Hydrogel Electrodes for Energy Storage and Sensing Applications

Integrating electroactive materials into mechanically resilient hydrogels remains a major challenge in the development of next-generation wearable electronics. In this work, we introduce a novel strain-induced self-wrinkling strategy to fabricate a multifunctional, sandwich-structured hydrogel electrode composed of polyacrylic acid (PAA), chitosan(CS), and polyvinyl alcohol (PVA). The resulting APC (PAA/CS/PVA) hydrogel demonstrates exceptional mechanical properties achieving a tensile strain of 495% and supporting loads up to 500 g without structural failure. Cryo-polymerization of pyrrole on frozen, pre-stretched hydrogels produced a conformal polypyrrole (PPy) layer on the micro-wrinkled surface of the APC matrix. The APCP hydrogel exhibits a significantly enlarged electroactive interface and enhanced PPy adhesion. APCP-based all-in-one supercapacitor delivers a high areal capacitance of 110.21 mF cm -2 at 0.5 mA cm -2 and power density of 2394.76 μW cm -2 at 5 mA cm -2 . The self-wrinkled surface endows the hydrogel with high strain sensitivity, enabling real-time monitoring of human joint and finger movements. This work provides a scalable and versatile strategy to constructe multifunctional all-in-one hydrogel systems for integrated energy storage and wearable sensing applications.