Bionic Single-Electrode Electronic Skin Unit Based on Piezoelectric Nanogenerator

Moravec's paradox shows that low-level sensorimotor skills are more difficult than high-level reasoning in artificial intelligence and robotics. So simplifying every sensing unit on electronic skin is critical for endowing intelligent robots with tactile and temperature sense. The human nervous system is characterized by efficient single-electrode signal transmission, ensuring the efficiency and reliability of information transmission under big data conditions. In this work, we report a sensor based on a single-electrode piezoelectric nanogenerator (SPENG) by electrospun polyvinylidene fluoride (PVDF) nanofibers that can realize steady-state sensing of pressure integrating cold/heat sensing on a single unit. Piezoelectric signals appear as square wave signals, and the thermal-sensing signals appear as pulse signals. Therefore, the two signals can be acquired by a single unit simultaneously. The SPENG overcomes the shortcoming of electronic skins based on a single-electrode triboelectric nanogenerator (STENG), which can sense only dynamic movement and cannot sense temperature variations. The new sensor configuration uses a capacitor instead of the STENG's ground wire as a potential reference, allowing it to be used for truly autonomous robots. At the same time, the traditional advantages of polymer piezoelectric materials, such as flexibility, transparency, and self-powered advantages, have also been preserved.