Anti-freezing, water-retaining, conductive, and strain-sensitive hemicellulose/polypyrrole composite hydrogels for flexible sensors

Abstract

High-performance conductive hydrogels are desired for the development of flexible wearable sensors. However, it remains a challenge to simultaneously realize high stretchable, freezing tolerance, and attractive conductivity through a simple approach. In this work, we present stretchable, water retention, anti-freezing, and conductive hemicellulose/polypyrrole (H/PPY) composite hydrogels for application in epidermal strain sensors via freezing-thawing method. The composite hydrogels were obtained using hemicellulose as a hydrophilic carrier and polypyrrole as a conductive matrix. The freezing and thawing temperatures of the hydrogels decreased and the conductivity increased benefiting from the introduction of glycerol and NaCl. The hydrogels had good mechanical properties, remodeling ability and water retention after storage for 7 days. In addition, the strain sensors assembled by hydrogels accurately monitored the signals of human motions with good strain sensing durability. It is expected that the as-prepared hydrogels have the potential to be applied in the fields of wearable devices.