Recent advances in flexible iontronic pressure sensors: materials, microstructure designs, applications, and opportunities

Flexible iontronic pressure sensors are emerging flexible pressure sensors with extraordinary sensing performances, such as high sensitivity, outstanding resolution, and strong signal intensity due to the formation of electrical double-layer capacitance. In recent years, significant advancements have been made in the preparation and application of flexible iontronic pressure sensors in the fields of electronic skins and wearable electronics. In this review, recent advances in flexible iontronic pressure sensors are comprehensively overviewed from the perspective of key performance indicators, such as sensitivity, linearity, response/recovery time, durability, accuracy, and detection range. The factors influencing each performance indicator are systematically elaborated to give readers a deep understanding. Then, we systemically introduce strategies to enhance sensing performances of flexible iontronic pressure sensors, including material choosing and structural design of electrodes and dielectric layers. Subsequently, the applications of flexible iontronic pressure sensors in health monitoring, information transmission, human-machine interaction, and spatial pressure mapping are comprehensively introduced. Finally, the directions for future development of flexible iontronic pressure sensors are thoroughly discussed. This review provides recent advances in flexible iontronic pressure sensors including strategies to enhance sensing performances and their applications and discusses future directions for implementing these advancements in practical applications.