Hybrid porous micro structured finger skin inspired self-powered electronic skin system for pressure sensing and sliding detection

Fingertip is the most sensitive region in human body due to the unique fingerprint patterns and interlocked structure between epidermal-dermal, which amplify the tactile stimuli and enhance the sensitivity. Inspired by the complicated anatomical structure, we fabricated a finger skin inspired e-skin system composed of fingerprint inspired triboelectric generator (TENG), epidermal-dermal inspired hybrid porous microstructure (HPMS) pressure sensor and subcutaneous fat inspired fabric based porous supercapacitor (FPSC). The TENG is responsible for detecting sliding direction and speed with the help of the four spiral electrodes, which adopt the frequency rather than the amplitude to detect the signal to avoid interfere from the environment. The HPMS, on the one hand, integrates the advantages from both the microstructure and porous structure to enhance the sensitivity further. On the other hand, the sensitivity of HPMS sensor is tunable by designing the shape and porosity of the HPMS, which is proved by theory, simulation and experiment. The FPSC, which can tolerate some degree of compression, works to supply energy for the pressure sensor. In this way, the sensor system can work independently without external battery. As a proof-of-concept demonstration, this sensor system has been used to detect complex action including pressure and sliding. During this process, the pressure and sliding direction and speed can be detected simultaneously without connecting to external energy source, showing its potential application area in soft robot and wearable devices.