Physically crosslinked hydrogel based on silver nanowires with a discontinuous rigid framework for robust, sensitive, antibacterial, and biocompatible flexible sensors

Abstract

Conductive hydrogels as flexible sensors fulfill the essential requirements of realtime monitoring and sensitive transmission in the fields of human-machine interaction. However, it is still a great challenge to integrate satisfying mechanical properties, sensitivity, antibacterial efficacy, and biocompatibility into one hydrogel sensor while ensuring a precise output signal. Herein, ultrathin silver nanowires (AgNWs) were prepared by controlling the growth of Ag atoms in (111) crystal planes within the Ethylene Glycol-Polyvinylpyrrolidone (EG-PVP) reduction system. Then, multifunctional hydrogel (SA-SH-AgNWs/PVA) was developed by physically crosslinking polyvinyl alcohol (PVA) and thiol-modified sodium alginate (SA-SH) in AgNWs aqueous solution through freeze-thaw circulation and Ca2+ crosslink. The AgNWs were adsorbed onto sodium alginate (SA) chains through electrostatic adsorption with thiol groups (-SH), forming a discontinuous rigid framework structure with a 278 % increase in tensile strength. The uniform dispersion of AgNWs within the hydrogel offers good sensing performance: gauge factor (GF) of 2.40 and sensitivity (S) of 3.24 × 10−2 kPa−1, and satisfying antibacterial abilities. What’s more, the obtained hydrogel can serve as stretching or compressing sensors to detect tiny yet intricate changes of human bodies. Therefore, the hydrogel is a great inspiration for the development of portable, intelligent, and highly flexible sensors.