Highly Stretchable, Sensitive, and Durable Ag/Tannic\nAcid@Graphene Oxide-Composite Hydrogel for Wearable Strain Sensors

Abstract

Flexible\nand wearable strain sensors have received extensive attention\nin the preparation of human–machine interface equipment, intelligent\nrobots, and personalized health-monitoring biosensors. However, it\nhas been a formidable challenge to develop materials with satisfying\nstretchability, sharp and quick sensitivity, and good linearity. Herein,\nwe report a multifunctional nanocomposite hydrogel with outstanding\nstretchability, fatigue resistance, and electrical conductivity by\nadding Ag nanoparticle-coated graphene oxide (Ag/TA@GO)-based nanocomplexes\ninto a polyacrylamide (PAM) hydrogel matrix. This Ag/TA@GO-PAM nanocomposite\nhydrogel shows an ultrahigh stretchability of 1250% and excellent\nconductivity (0.15 S·m^–1). The sensitivity\nis improved to GF = 3.1; meanwhile, the preeminent linear sensing\nproperty is achieved in the ultrawide strain range of 0 to 1000%,\nwith a high <i>R</i>² value of 0.994. Moreover,\nwhen the Ag/TA@GO-PAM hydrogel is assembled into a wearable strain\nsensor with a sandwiched structure, it can detect large and delicate\nmotions (for example, facial expression and pronunciation), with excellent\nsensitivity and durability. In addition, the nanocomposite hydrogel\nis further explored from practical aspects for circuit assembly and\nrepair, E-skin of bionic robots, and information encryption. Therefore,\nthis study provides a basis for multifunctional wearable nanocomposite\nhydrogel sensors.