Anti-bacterial, anti-freezing starch/ionic liquid/PVA ion-conductive hydrogel with high performance for multi-stimulation sensitive responsive sensors

Abstract

The rapid development of the times has aroused the concern for the full usage of renewable resources and the sustainable development of the environment. Meanwhile, complex social activities have also put forward many requirements for sensor industry. Traditional hydrogel sensors are easy to lose water in daily environment and freeze at low temperatures, as well as being attacked by bacterial during repeated use, thus affecting the service life of the device, which are all problems to be solved by hydrogel flexible equipment. These urgent problems are crucial to the development of hydrogel flexible devices. In this work, starch/polyvinyl alcohol (PVA) is used as dual-network hydrogel substrate due to the advantages of renewable and biocompatibility. The internal compatibility of starch/PVA hydrogel is greatly improved by regulating the ratio of ionic liquid/ethylene glycol/water ternary solvent system. Multiple hydrogen bonding endows starch/ionic liquid/PVA ionic conductive hydrogel with high mechanical properties (tensile strain, modules and toughness of 1250.29 %, 1324.43 kPa, 9008.88 kJ m−3, respectively), and excellent anti-freezing (-128.9℃), anti-bacterial and electrical conductivity. The assembled hydrogel sensor could effectively detect external stimulations such as strain/pressure. It also has high sensitivity characteristics over an ultra-wide strain range (GF = 0.99 below 55 %, 2.19 at 55 %–250 %, 2.49 at 250 %–650 %, and 3.28 at 650 %–1000 %), as well as stably recognize human movements and physiological signals. All in all, this work brings new inspiration for low-cost, environmentally adaptable, sustainable wearable flexible devices.