Phase‐Separation Enhanced Piezoionic Effect in Cellulose/Alginate Hydrogels for High‐Sensitivity Self‐Powered Sensing

ABSTRACT The piezoionic effect, as an emerging force‐sensing mechanism, shows great potential in self‐powered sensing applications. However, the sensitivity of conventional piezoionic sensors remains relatively low due to the limited difference in anion and cation diffusivity, which restricts their applicability in high‐precision sensing. Here, a cellulose/alginate hydrogel with a controllably phase‐separated structure, enabling a substantial enhancement in piezoionic output is developed. Through a sequential cross‐linking strategy, a biphasic network structure composed of cellulose and aluminum alginate is successfully constructed. The cellulose phase provides structural stability, and the macroporous aluminum alginate phase enables rapid ion diffusion while the strong coordination between aluminum ions and alginate selectively immobilizes cations, thereby significantly enhancing ion diffusion difference under pressure and improving the piezoionic sensor performance. The optimized hydrogel sensor exhibits high sensitivity (14.13 mV kPa −1 ), fast response (60 ms), and excellent cycling stability, enabling high‐precision monitoring of weak physiological signals while also functioning as a micro‐power source for electronic devices. This work provides an innovative structural design strategy for developing high‐performance, environmentally friendly piezoionic materials and sensing systems.