Recent advances and new frontier of flexible pressure sensors: Structure engineering, performances and applications

Global research on flexible pressure sensors for evaluating human wellness and intelligent robotics is intensifying due to their advantages of excellent flexibility, lightweight design, high sensitivity and ease of integration. To facilitate practical applications, challenges associated with high-performance must be addressed, such as the trade-off between high sensitivity and a wide linear sensing range, fast response/recovery time, limited hysteresis, and stability under both dynamic and static pressure conditions. Moreover, ensuring the sensors' reliability under various interferences and their multi-functionality to meet diverse usage requirements is essential for future applications. In this review, we summarize the latest advancements in multiple microstructures within the active layer and/or electrodes, which ensure excellent sensing performances, superior reliability and multifunctional features. Specifically, we focus on the design, working principles and sensing features of advanced micropattern, micropores, fiber-network, and hybrid microstructures in pressure sensors based on hierarchical micro-/nano-structure, conductive gradient coatings or multilayer structures. Additionally, the applications of microstructured pressure sensors in the fields of healthcare and human-machine interaction are summarized. Finally, we discuss the challenges and future prospects in the development of the next generation of flexible pressure sensors.