Self-healing, Stretchable, Temperature-Sensitive and Strain-Sensitive Hydrogel-based Flexible Sensors

• Published in: Chinese journal of polymer science Vol. 41; no. 3; pp. 334 - 344
• Main Authors: Zhao, Chun-Xia, Guo, Min, Mao, Jie, Li, Yun-Tao, Wu, Yuan-Peng, Guo, Hua, Xiang, Dong, Li, Hui
• Format: Journal Article
• Language: English
• Published: Singapore Springer Nature Singapore 01.03.2023; Springer Nature B.V
• Subjects: Acrylamide; Ambient temperature; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Condensed Matter Physics; Flexible components; Graphene; Human motion; Hydrogels; Hydrogen bonding; Industrial Chemistry/Chemical Engineering; Motion perception; Motion stability; Polymer Sciences; Recoverability; Research Article; Robotics; Sensors; Stretchability; Wrist; Dual temperature-strain sensitive; Monitor body motions; Self-healing; Hydrogel sensor
• ISSN: 0256-7679; 1439-6203
• DOI: 10.1007/s10118-022-2854-6

Flexible hydrogels have shown promise as strain sensors in medical monitoring, human motion detection and intelligent robotics. For a hydrogel strain sensor, certain challenges need to be urgently addressed for practical applications, such as the damage caused by external effects, leading to equipment failure, and the inability to perceive ambient temperature, resulting in single functionality. Herein, a stretchable, self-healing and dual temperature-strain sensitive hydrogel, with a physically-crosslinked network, is designed by constructing multiple dynamic reversible bonds. Graphene oxide (GO) and iron ions (Fe 3+ ) act as dynamic bridges in the cross-linked network and are mediated by the covalent and hydrogen bonding, rendering excellent stretchability to the hydrogel. The reversible features of coordination interactions and hydrogen interactions endow excellent recoverability and self-healing properties. Moreover, the incorporated N -isopropyl acrylamide (NIPAM) provides excellent temperature responsiveness to the hydrogel, facilitating the detection of external temperature changes. Meanwhile, the hydrogels exhibited strain-sensitivity, with a wide working range of 1%–300%, fast response and electrical stability, which can be used as flexible sensors to monitor body motions, e.g. , speaking and the bending of finger, wrist, elbow and knee. Overall, the hydrogel possesses dual sensory capabilities, combining external temperature and strain, for potential applications in wearable multifunctional sensing devices.