Organic-Inorganic Hydrogel Strain Sensors Based on Methacryloyl Ethoxy Trimethyl Ammonium Chloride and Bentonite

Abstract

Flexible wearable electronic devices based on hydrogels have immense potential in a wide range of applications. However, many existing strain sensors suffer from significant limitations including poor mechanical properties, low adhesion, and insufficient conductivity. To address these challenges, this study successfully developed an organic-inorganic double-network conductive hydrogel using acrylic-modified bentonite (AABT) as a key component. The incorporation of AABT significantly enhanced the mechanical properties of the ATHG@LiCl hydrogel, achieving an impressive stretchability of 4000% and tensile strength of 250 kPa. Moreover, it improved the electrical conductivity of the hydrogel to a maximum of 1.53 mS/cm. The catechol structure of tannic acid (TA) further augmented the adhesive properties of the ATHG@LiCl hydrogel toward various substrates such as copper, iron, glass, plastic, wood, and pigskin. The addition of lithium chloride (LiCl) and dimethyl sulfoxide (DMSO) endowed the hydrogel with exceptional freezing resistance and flexibility, even at low temperatures of -20 °C. Remarkably, the hydrogel maintained a conductivity of 0.53 mS/cm under these conditions, surpassing the performance of many other reported hydrogels. Furthermore, the ATHG@LiCl hydrogel demonstrated outstanding characteristics, such as high sensitivity (gauge factor GF=4.50), excellent transparency (90%), and reliable strain-sensing capabilities, indicating that the ATHG@LiCl hydrogel is a highly promising candidate for flexible wearable soft materials, offering significant advancements in both functionality and performance.