Phytic acid-based super antifreeze multifunctional conductive hydrogel for human motion monitoring and energy harvesting devices

Abstract

Conductive hydrogels have broad application prospects in the field of self-powered sensors and energy harvesting devices due to their good electrical conductivity and flexibility. However, at low temperatures, conductive hydrogels are usually frozen, resulting in problems such as poor electrical conductivity and flexibility, which seriously hinder the application of these fields. To address these challenges, phytic acid (PA) was employed as the crosslinker and antifreezing agent in this study. Polyvinyl alcohol (PVA), 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS), chitosan (CS), and PA were used as raw materials to successfully synthesize PVA/AMPS/CS/PA (PACP) multifunctional conductive hydrogels with outstanding antifreeze and water retention properties (freezing point below −80 °C, 30-day water loss rate of 3.5%). In addition, PACP hydrogels exhibit exceptional electrical conductivity of up to 9.4 S/m, along with antibacterial and biocompatible properties, enabling their utilization as wearable sensors on human skin tissue. Notably, the PACP hydrogel-based triboelectric nanogenerator (PACP-TENG) excels in accurately monitoring human motion and powering small electronic devices, facilitating remote control of small light switches. The resulting open circuit voltage is as high as 314 V at 25 °C and about 110 V at low temperature. Therefore, PACP hydrogels with excellent properties are expected to expand their applications in these fields.