Stretchable and tough conductive hydrogels for flexible pressure and strain sensors

• Published in: Journal of materials chemistry. B, Materials for biology and medicine Materials for biology and medicine, 2020-04, Vol.8 (16), p.3437-3459
• Main Authors: Wang, Zhenwu, Cong, Yang, Fu, Jun
• Format: Article
• Language: English
• Subjects: Automation; Biocompatibility; Biomimetics; Biosensing Techniques; Capacitance; Conductivity; Elastomers; Electric Conductivity; Flexible components; Humans; Hydrogels; Hydrogels - chemistry; Manufacturing engineering; Mechanical properties; Molecular Structure; Network reliability; Particle Size; Pressure; Reviews; Robotics; Sensors; Strain; Surface Properties; Wearable Electronic Devices; Wearable technology
• ISSN: 2050-750X; 2050-7518
• DOI: 10.1039/c9tb02570g

Flexible pressure and strain sensors have great potential for applications in wearable and implantable devices, soft robotics and artificial skin. Compared to flexible sensors based on filler/elastomer composites, conductive hydrogels are advantageous due to their biomimetic structures and properties, as well as biocompatibility. Numerous chemical and structural designs provide unlimited opportunities to tune the properties and performance of conductive hydrogels to match various demands for practical applications. Many electronically and ionically conductive hydrogels have been developed to fabricate pressure and strain sensors with different configurations, including resistance type and capacitance type. The sensitivity, reliability and stability of hydrogel sensors are dependent on their network structures and mechanical properties. This review focuses on tough conductive hydrogels for flexible sensors. Representative strategies to prepare stretchable, strong, tough and self-healing hydrogels are briefly reviewed since these strategies are illuminating for the development of tough conductive hydrogels. Then, a general account on various conductive hydrogels is presented and discussed. Recent advances in tough conductive hydrogels with well designed network structures and their sensory performance are discussed in detail. A series of conductive hydrogel sensors and their application in wearable devices are reviewed. Some perspectives on flexible conductive hydrogel sensors and their applications are presented at the end. This review summarises recent advances in stretchable and tough conductive hydrogel sensors for wearable and implantable devices.