Flexible multifunctional TPU strain sensors with improved sensitivity and wide sensing range based on MXene/AgNWs

Flexible electronic devices have received increasing attention for potential application in wearable human motion monitoring, healthcare, and thermal management. Nevertheless, flexible electronics with high sensitivity and a wide strain range for accurate health monitoring of human movement is an urgent issue that needs to be addressed. Herein, flexible sensors with 3D conductive networks based on electrospun thermoplastic polyurethane (TPU) mats were prepared by coupling silver nanowires (AgNWs) and MXene Ti3C2Tx for human health monitoring and thermal management. The strain sensors containing only AgNWs or Ti3C2Tx conductive materials exhibit high sensitivity and a wide strain range because of the difference in the structure of conductive network between 1D AgNWs and 2D Ti3C2Tx nanomaterials, respectively. The advantages of 3D conductive networks are demonstrated in the sensitivity and sensing range of the MXene/AgNWs/TPU sensor due to the interaction between AgNWs and Ti3C2Tx and the 3D conductive network formed. The MXene/AgNWs/TPU sensor can be used not only for human physiological health monitoring (pulse monitoring) but also for human motion monitoring (elbow motion), because of its wide strain detection range (0-120% strain) and high sensitivity (measurement factor up to 33,100). As MXene is decorated by hydrogen bonding or electrostatic interaction, the MXene/AgNWs/TPU strain sensor exhibits excellent cycling stability (1000 cycles). Furthermore, the outstanding electrical heating and photothermal performances of the MXene/AgNWs/TPU strain sensors are served as an important function in protecting human health in cold environments and assisting the body in medical rehabilitation. Based on their excellent performance, the strain sensors not only monitor body movements over a wide strain range (e.g., knee flexion) and subtle human physiological signals (e.g., pulse waves), showing great potential for applications in human health monitoring and thermal management.