A "soft and Hard" Bioinspired Hydrogel for Enhanced Pressure Sensing

Currently, ionic hydrogel capacitive pressure sensors (CPSs) with high performances are urgently needed in the field of flexible pressure sensors. Biological tissues generally exhibit excellent mechanical properties and stimuli-responsive ability owing to their well-developed microstructures. Herein, we utilized poly(vinyl alcohol) (PVA) and chrome shavings to engineer a novel hydrogel with a "soft and hard" composite structure inspired by biological tissues. The bioinspired hydrogel has two structural characteristics: collagen fibril-PVA mixed synapses and a fiber skeleton structure with nested PVA pores, which endow the material with outstanding sensing performances and mechanical properties. The assembled ionic hydrogel CPS possesses high sensitivities of 4.20 kPa(-1) (0-3 kPa), 1.09 kPa(-1) (3-9 kPa), and 0.28 kPa(-1) (9-54 kPa) and a wide sensing range of 0-54 kPa. In addition, glycol and glycerol were introduced to overcome the drying problem of the hydrogel sensor. This work offers a new perspective for the preparation of high-performance and cost-effective ionic CPSs.