Biocompatible piezoionic eutectogel sensor for self-powered physiological monitoring

Piezoionics holds promise for self-powered bioelectronics, yet existing hydrogel and elastomer systems are often limited by poor biocompatibility, environmental instability, and low output. Here, we report a biocompatible deep eutectic solvent-polyvinyl alcohol (DES-PVA) eutectogel featuring a robust piezoionic response and practical wearable sensing capabilities. By incorporating a choline chloride-glycerol DES into a PVA network, we engineer tailored hydrogen bonds that selectively constrain choline cations while enabling rapid chloride anion transport, thereby amplifying the piezoionic response to achieve a sensitivity of 60 mV kPa^-1. In vitro assays verify the excellent biocompatibility of the eutectogel. Furthermore, practical application demonstrations underscore its capability for precise and continuous monitoring of diverse physiological signals, including pulse waveform and electrocardiograms (ECG), with fidelity comparable to commercial sensors. Overall, this work establishes a self-powered, bio-compliant epidermal platform for advanced iontronics and bioelectronics.