Design of Stretchable\nand Conductive Self-Adhesive\nHydrogels as Flexible Sensors by Guar-Gum-Enabled Dynamic Interactions

Abstract

The limited elasticity and inadequate bonding of hydrogels\nmade\nfrom guar gum (GG) significantly hinder their widespread implementation\nin personalized wearable flexible electronics. In this study, we devise\nGG-based self-adhesive hydrogels by creating an interpenetrating network\nof GG cross-linked with acrylic, 4-vinylphenylboronic acid, and Ca²⁺. With the leverage of the dynamic interactions (hydrogen\nbonds, borate ester bonds, and coordination bonds) between −OH\nin GG and monomers, the hydrogel exhibits a high stretchability of\n700%, superior mechanical stress of 110 kPa, and robust adherence\nto several substrates. The adhesion strength of 54 kPa on porcine\nskin is obtained. Furthermore, the self-adhesive hydrogel possesses\nstable conductivity, an elevated gauge factor (GF), and commendable\ndurability. It can be affixed to the human body as a strain sensor\nto obtain precise monitoring of human movement behavior. Our research\noffers possibilities for the development of GG-based hydrogels and\napplications in wearable electronics and medical monitoring.