Zwitterionic Hydrogel with High Transparency, Ultrastretchability,\nand Remarkable Freezing Resistance for Wearable Strain Sensors

Abstract

Multifunctional\nhydrogel with outstanding conductivity and mechanical\nflexibility has received enormous attention as wearable electronic\ndevices. However, fabricating transparent, ultrastretchable, and biocompatible\nhydrogel with low-temperature stability still remains a tremendous\nchallenge. In this study, an ultrastretchable, highly transparent,\nand antifreezing zwitterionic-based electronic sensor is developed\nby introducing zwitterionic proline (ZP) into gellan gum/polyacrylamide\n(GG/PAAm) double network (DN) hydrogel. The existence of ZP endows\nthe hydrogel with remarkable frost resistance. The toughness and transparency\nof zwitterionic Ca-GG/PAAm-ZP DN hydrogel can be maintained down to\n−40 °C. Also, the zwitterionic hydrogel shows good biocompatibility\nand protein adsorption resistance. The zwitterionic Ca-GG/PAAm-ZP\nDN hydrogel-based strain sensor can accurately monitor human motions\n(such as speaking and various joint bendings) under a broad temperature\nrange from −40 to 25 °C. The zwitterionic Ca-GG/PAAm-ZP\nDN hydrogel-based strain sensor will be of immense value in the field\nof wearable electronic devices, especially for extreme environment\napplications.