Flexible wearable piezoresistive physical sensors with photothermal conversion and self-cleaning functions for human motion monitoring

Flexible wearable sensors can mimic the sensing ability of the skin and transform deformation stimuli into monitorable electrical signals, making them favorable in the fields of personalized healthcare, human motion monitoring, and remote monitoring systems. Here, an innovative piezoresistive physical sensor based on fluorine-free superhydrophobic dodecyltrimethoxysilane/polypyrrole/carbon nanotube (DTMS/PPy/CNT) cotton fabrics (DPC-CFs) was assembled via an environmentally safe and simple dip-coating method. The flexible wearable sensor exhibits self-cleaning capability (high water contact angle of 158.3°), good electrical conductivity (45.43 S m^-1), photo-thermal conversion (surface temperature up to 94.8 °C), rapid response/recovery time (60 ms/50 ms), and excellent stability (>2400 cycles), and was successfully applied to dynamic monitoring of a series of human activities such as wrist pulse, voice recognition, and finger bending. Furthermore, the development of the superhydrophobic piezoresistive physical sensor derived from biodegradable cotton fabrics means an important step forward in the evolution of wearable sensors, which not only provide better coverage of three-dimensional irregular surfaces to capture mechanical stimulation signals but also demonstrate better comfort, flexibility and versatility. It is foreseen that such sensors, which are fabricated by utilizing abundant renewable and biodegradable green raw materials, have a broad application prospect in the next generation of biomedical systems, fitness, and human-computer interactive devices.