Plant-Derived Hydrogels with High Stretchability and Adhesion for Multifunctional Sensors

Hydrogels have broad application prospects in biomedicine, energy, and tissue engineering due to their high water content, adjustable physicochemical properties, and flexibility. In general, the poor stretchability and adhesion of hydrogels limit their application in flexible wearable electronics. In this work, a composite hydrogel (GM hydrogel) with excellent adhesion, stretchability, and conductivity was prepared by a one-pot synthesis process through the hydrogen-bonding interaction between P(AM-co-AA)) and gallic acid (GA). Natural plant polyphenol GA not only enhances the mechanical properties of the hydrogel (maximum tensile strain of 890% and maximum tensile stress of 238 kPa) but also gives the hydrogel adhesion (9 kPa). GM hydrogel can be further used to construct strain sensors and self-powered sensors. GM hydrogel strain sensors can be attached to finger joints to monitor and distinguish the angles of finger joint bending. Self-powered sensors based on GM hydrogels can stably transmit encrypted signals. Therefore, multifunctional GM hydrogels can be used for electronic skin, human motion monitoring, and wearable biosensors.