Key factors and performance criteria of wearable strain sensors based on polymer nanocomposites

Recently, there has been growing demand for wearable electronic devices/strain sensors in soft robotics, body-health monitoring, human-machine interfaces, and human motion detection. Wearable strain sensors feature fast and multistimuli sensitivity, high flexibility, ultrastretchability, and biocompatibility. Although progress in flexible strain sensors is exponential, the production of wearable sensors faces several challenges, such as reliability and reproducibility. An in-depth understanding of the sensing mechanisms of flexible strain sensors based on' polymeric nanocomposites is needed to fabricate reliable and reproducible sensors and move from the prototype phase into the industry phase. In this review, types of strain sensors and key parameters such as linearity, gauge factor (sensitivity), hysteresis, and durability are explained in the context of recently published work. In addition, current challenges and perspectives in relation to wearable strain sensors are delineated.