Highly sensitive and stretchable CB/GNPs-TPU strain sensor with porous microstructure for multifunctional strain sensing

Multifunctional flexible strain sensors have garnered significant attention in recent years, particularly in the fields of smart wearable devices and human health monitoring. However, the trade-off between high sensitivity and a wide strain range limits their practical applications. This study presents a porous TPU/CB framework prepared using a water vapor-induced phase separation method, which can deform like a spring when stretched, thereby providing the sensor with a greater strain range. The graphene nanoplatelets (GNPs) were subsequently incorporated into the pores of the porous framework through ultrasonic treatment, which enhanced the sensor's sensitivity while preventing increased brittleness caused by the aggregation of conductive fillers. This structure establishes a stable conductive network, enabling the sensor to achieve high sensitivity (GF = 5902.4) across a wide strain range (327 %) while also demonstrating excellent stability and durability (over 7000 stretching/releasing cycles). The sensor can detect not only simple limb movements, such as bending of the arms and knees but also subtle muscle activities, including facial expressions and throat vocalization, thus bringing excellent human-computer interaction experience. These remarkable features position the sensor for promising applications in smart wearables and human health monitoring.