Facile preparation of micropatterned thermoplastic surface for wearable capacitive sensor

Highly sensitive and flexible capacitive sensors are in great demand for wearable electronics, which can be achieved by preparing micropatterns on their dielectric layer surface. However, most micropatterns are often molded with the silicon template acquired by complex processes which are very time-consuming and costly. Here, a dielectric layer with micropatterned arrays was prepared on the thermal plastic polyurethane (TPU) film with the help of a hot-air-gun, then assembled with an ITO/PET electrode to develop a capacitive sensor with a sandwich structure. The capacitive sensor based on TPU/ITO/PET composites exhibits sensitivity of over 0.026 kPa−1, shorter response/recovery time of 99 ms, wide working range (0–13 kPa) and remarkable stability over 5000 cyclic pressing or bending. Interestingly, such sensor can monitor various physiological signals of people (e.g., voice signal, finger bending and breath). More importantly, it can distinguish different sign languages according to capacitive changes in the case of different finger gestures. The method proposed in this study will paves a new avenue for the facile preparation of micropatterned surface to improve the performance of flexible capacitive sensors.