Hydrogel-Based Flexible and Wearable Sensors

Abstract

Wearable electronic sensors are a group of emerging technologies that have demonstrated excellent potential in soft robotics, human-machine interfaces, electronic skin, body movement tracking, and remote health monitoring. Compared with traditional sensors, these sensors have considerable advantages such as great flexibility, outstanding conformability, portability, and cost-effectiveness. They have many applications such as wearable/implantable strain sensors, soft robotics, monitoring of vital signs in healthcare areas, electronic skins, and energy storage electrodes, and they have gained considerable research interest. Among the various electrode materials, hydrogel-based materials have exceptional biocompatibility, flexibility, and stretchability, which makes them appealing candidates for wearable flexible sensors. Therefore, the purpose of this chapter is to present and categorize all types of hydrogel-based flexible wearable sensors (HB-FWSs), explain in detail all preparation methods, features, applications, and disadvantages of each method, propose alternative methods to enhance the intrinsic features of these sensors, and review the recent design, material, and method advances. Ultimately, challenges, future outlooks, and promising applications are discussed.