A Flexible Pressure Sensor Based on an Interlocked Micropillars Array With Secondary Nanoprotrusions for Health Monitoring.

Flexible pressure sensors are an essential component in artificial systems to monitor human health. Recently, flexible pressure sensors with micro-nanostructures in interlocked geometry have attracted extensive attention because they effectively improve the sensing performance. However, it is a challenge that the fabrication methods are complex and expensive, and the layered interface between microstructure and nanostructure is unstable. Here, a flexible pressure sensor with an interlocked polydimethylsiloxane (PDMS) micropillars array combined secondary nanoprotrusions on their surfaces is proposed, which can be shaped in one step with merits of simplicity, controllability and low cost. The unique combined micro-nanostructures ensure the sensor with a wide linear range (0~32 kPa), relatively high piezoresistive sensitivity (26.08 Ω/kPa), low detection limit (15 Pa), fast response speed (response time is 56 ms, and relaxation time is 140 ms) and excellent stability (>1000 cycles). These superior properties set a foundation for applying the sensor in detecting various human physiological signals from pulse to joint deformation. Based on this sensor, a smart mask integrated system is proposed, displaying and recording breathing conditions in real time. These results demonstrate that the sensor can be used in health monitoring and disease diagnosis, as well as its potential application in other wearable devices.