Transparent, Stretchable and Direct Skin-Touchable Multi-Functional Electronic Skin Sensors

Multi-functional electronic skin (e-skin) sensors, which can be directly skin-attachable to human body for normally monitoring the outside illumination environment and the movement situations of human body, can play a vital role in personal health and body rehabilitation. However, multi-functional e-skin sensors with transparency, stretchability, and skin-attachable to human body still keep challenge. In this paper, an optical transparent, low resistivity, good flexibility, light-sensitivity, and biocompatible multilayer film e-skin sensor was fabricated with the interpenetrating networks containing the silver nanowire (Ag NW) and the azobenzene buried in between silk fibroin (SF) film and poly (dimethylsiloxane) (PDMS) film. The multilayer film e-skin with thickness of 150 μm can light a light-emitting diode (LED) chip under direct current, and the super thin SF film of the e-skin sensor can provide good biocompatibility for human skin due to similar human skin protein structures, and the interpenetrating networks containing the silver nanowire (Ag NW) and the azobenzene can produce an obvious response for UV illumination, human body bending and/or uniaxial tensile. Moreover, the three-sublayer-structured e-skin is low-cost, less equipment-intensive, and easily mass-produced, and be widely used in commercial applications of medicine, bionic-robot, and other wearable electronics.