Strain-insensitive static and dynamic pressure sensing in a piezoionic hydrogel under 200% stretching

Self-powered pressure sensing underpins autonomous wearable systems, yet piezoelectric and triboelectric routes convert only dynamic stimuli, while approaches that capture static pressure or tolerate large strain stay passive and need an external supply. Here, a self-powered piezoionic sensor that transduces both static and dynamic pressure and stays insensitive to tensile strain up to 200% is reported, built on a micropillar-patterned hydrogel of Sn-doped BaTiO 3 (Sn-BTO) nanorods, a cationic copolymer network, and LiCl. Loading polarizes the Sn-BTO nanorods to set up an internal field, while the cationic network immobilizes the anions so that Li + alone migrates, converting force into an ionic voltage without external power. The micropillar architecture confines the stress and decouples the output from stretching, holding the response within 3.7% (dynamic) and 4.3% (static) across the full strain range. The sensor resolves 1.5 Pa, is stable over 10,000 cycles, and tracks the radial artery pulse during body motion.