Mould-Free Skin-Inspired Robust and Sensitive Flexible Pressure Sensors With Hierarchical Microstructures

Abstract

Flexible microscopic pressure sensors are important to the emerging fields of intelligent robots and advanced healthcare. However, common microstructured pressure sensors often require sophisticated mould 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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$33\,\,kPa^{-1}$ </tex-math></inline-formula> below 5 kPa, more than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.6\,\,kPa^{-1}$ </tex-math></inline-formula> under 108 kPa), also deliver low hysteresis (within 8%), rapid response (less than 48 ms), and ultralow operation voltage ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10~{\mu }V$ </tex-math></inline-formula> ). We illustrate that such self-patterned high-performance pressure sensors can be applied to convert the pressure stimulus into spike-like signals in both low- and medium-pressure regimes, and are being able to clearly reveal the details of human pulse wave.