Mould-free skin-inspired robust and sensitive flexible pressure sensors with hierarchical microstructures

Flexible microscopic pressure sensors are important to the emerging fields of intelligent robots and advanced healthcare. However, common microstructured pressure sensors often require sophisticatedmould and/or material preparation, and yield limited pressure sensing performances. In this letter, we report a facile approach to design a scalable and stretchable mould-free sensitive layer with a unique hierarchical microstructure. Inspired by natural skin, a sensitive layer with interdigitated electrodes is utilized to constructed into resistive pressure sensors, which are able to robustly detect the pressure variations with high sensitivity in a wide dynamic range (about 33 kPa-1 below 5 kPa, more than 0.6 kPa-1 under 108 kPa), also deliver low hysteresis (within 8%), rapid response (less than 48 ms), and ultralow operation voltage (10 μV). We illustrate that such self-patterned highperformance pressure sensors can be applied to convert the pressure stimulus into spike-like signals in both lowandmedium- pressure regimes, and are being able to clearly reveal the details of human pulse wave.