High conductivity, low-hysteresis, flexible PVA hydrogel multi-functional sensors: Wireless wearable sensor for health monitoring

Addressing the issues of poor mechanical properties, high hysteresis, low conductivity, and weak fatigue resistance in hydrogels is key to expanding their use as flexible sensors. Herein, green raw materials such as polyvinyl alcohol, carboxymethyl chitosan, citric acid and sodium chloride were used to prepare high conductivity, low hysteresis, high toughness, recyclable hydrogels (PCCN) by regional crystallization and construction of multiple cross-linked network structures. The tensile strength, tensile strain and toughness of PCCN hydrogel reached 0.49 MPa, 481 % and 0.81 MJ/m 3 respectively. The PCCN hydrogel showed low hysteresis and high conductivity (4.96 S/m) in tests, and the PCCN-4 hydrogel was able to detect signals in different parts of the human body. When the PCCN-4 is assembled into the TENG as a charge collecting layer, it can output a voltage of about 100 V and be prepared as a self-powered sensor. Interestingly, by integrating the highly conductive, flexible and sensitive PCCN hydrogel strain sensor with a Bluetooth system, a wireless wearable sensor for health monitoring can be created. The work presented in this paper is expected to provide new approach to developing eco-friendly, flexible, and sensitive hydrogel-based sensors.