Self-Polarized Piezoelectric Hydrogels with Flexible-Rigid Networks for Ultrasensitive Multifunctional Sensors

Self-powered hydrogels address the critical limitations of conventional hydrogel devices, which suffer from continuous energy consumption and bulky power supplies. However, achieving both ultrasensitive performance and excellent flexibility remains a significant challenge. Here, we report a self-polarized piezoelectric double-network cellulose/poly(vinylidene fluoride-trifluoroethylene) (DNCP) hydrogel, which integrates a flexible cellulose framework with a rigid P(VDF-TrFE) network through covalent bonding, hydrogen bonding, and dipolar interactions. This innovative design enables the self-polarization of P(VDF-TrFE), achieving a high 75.1% β-phase fraction without external poling. The DNCP hydrogel exhibits excellent self-powered capability, ultrahigh sensitivity (11.1 mV kPa^-1), a detection limit as low as 0.8 kPa, skin-like flexibility, and robust stability. These properties establish it as a promising material platform for multifunctional sensors, enabling real-time, self-powered health monitoring and robotic hand control. This work represents a major advancement in next-generation sensing technologies, offering a compelling solution for wearable and robotic applications.