Pearl-Inspired Gelatin/Chitosan-Reinforced Conductive Hydrogel with High Strength, Freeze Resistance, and Stability for Flexible Wearable Sensors.

Inspired by the "brick-and-mortar" architecture of pearl oyster shells, a novel high-strength, highly conductive, and environmentally friendly hydrogel was fabricated via photopolymerization employing a dual-network design and solvent-exchange strategy. The resulting poly(vinyl alcohol) (PVA)/acrylic acid (AA)/gelatin (Gel)/tannic acid (TA)/quaternary ammonium chitosan (HACC) @ acetylene black (AB) (PAGTH-AB) composite hydrogel exhibits a tensile strength of 5.49 MPa, an elongation at break of 736%, a toughness of 22.07 MJ/m3, a Young's modulus of 0.69 MPa, and an electrical conductivity of 0.83 S/m, along with excellent freeze resistance, water retention, and long-term stability. As a flexible sensor, the hydrogel demonstrates a linear response over a broad strain range (0-500%), outstanding cyclic stability (2000 cycles), and a rapid dynamic response (336 ms). Even under frigid conditions, it enables real-time, precise monitoring of human motions such as finger, wrist, elbow, and knee joint movements, as well as gesture changes, and enables the accurate capture of dynamic writing trajectories. This work presents a novel and effective strategy for designing high-performance resilient hydrogels, offering a promising route for developing flexible electronic sensors with high strength and stability.