Work

Micropatterned Composite Hydrogel Sheet with Surface Electronic Conductive Network for Ultrasensitive Strain Sensing

Year: 2025

Type: article

Abstract: Conductive hydrogels hold great promise for wearable sensors but struggle with low sensitivity in small strain ranges. In this study, a micropatterned composite hydrogel sheet was developed by creating a continuous electronic conductive network with carbon nanotubes (CNTs) on a hydrogel sheet. The sheet was fabricated through a two-step synthesis of a polyvinyl alcohol/polyacrylic acid polymer network crosslinked by Zr4+ in a glycerol-water system, using sandpaper as the template. The first step ensured a close fit with the template, while the second step preserved the integrity and accuracy of the micropattern. The reverse sandpaper micropattern ensures that CNTs bond securely to the hydrogel and creates localized stress concentration during stretching. This results in controllable crack formation in the conductive network during stretching, allowing the sensor to maintain high sensitivity even in small strain ranges. The reversible Zr4+ crosslinking, hydrogen bonding, and glycerol confer the composite hydrogel sheet with self-healing, adhesion, antibacterial properties, good permeability, and extreme temperature tolerance. Consequently, the sensor exhibits ultrahigh sensitivity with gauge factors of 76.1 and 203.5 in small (0-30%) and larger (30-100%) strain ranges, respectively, and comfortable user experience. It is capable of detecting various activities ranging from subtle physiological signals to relatively large joint bending, as well as complex hand gestures and sports posture. This innovative structure and sensing mechanism offer a new direction for wearable electronic device design, leveraging stress concentration and controllable crack formation to enhance sensor performance.

Source: Gels

DOI: 10.3390/gels11110913