Wearable sensors are vital for the development of electronic skins to improve health monitoring, robotic tactile sensing, and artificial intelligence. Active materials and the construction of microstructures in the sensitive layer are the dominating approaches to improve the performance of pressure sensors. However, it is still a challenge to simultaneously achieve a sensor with a high sensitivity and a wide detection range. In this work, using three-dimensional (3D) vertical graphene (VG) as an active material, in combination with micropyramid arrays and lumpy holders, the stress concentration effects are generated in nano-, micro-, and macroscales. Therefore, the lumpily pyramidal VG film-based pressure sensor (LPV sensor) achieves an ultrahigh sensitivity (131.36 kPa-1) and a wide response range (0.1-100 kPa). Finite element analysis demonstrates that the stress concentration effects are enhanced by the micropyramid arrays and lumpy structures in micro- and macroscales, respectively. Finally, the LPV pressure sensors are tested in practical applications, including wearable health monitoring and force feedback of robotic tactile sensing.
Keywords: broad sensing range; high sensitivity; micropyramid arrays; stress concentration effect; vertical graphene.