Self-powered gold nanowire tattoo triboelectric sensors for soft wearable human-machine interface

A soft skin-like wearable device is an ideal next-generation human-machine interface (HMI) in that they can enable seamless information collection and relay anytime and anywhere. However, it is non-trivial to realize such soft HMI in the conventional way that electronics are designed and manufactured. Here, we report on an electronic tattoo-like, triboelectric, self-powered wearable sensor based on vertically aligned standing gold nanowires (v-AuNWs). Unlike traditional gold films, our elastomer-bonded v-AuNWs are intrinsically stretchable conductors that can bear exceptionally high strains without losing conductivity. In a single-electrode design, the v-AuNWs-based triboelectric sensor could still generate signals even under severe mechanical deformation, such as 500% of strain. The v-AuNWs could also be embedded into ultrathin elastomers, micro-patterned, peeled off and transferred to any receiving surfaces, leading to fabrication of skin-like triboelectric pressure-sensing tattoos on human skins for HMI applications. Such self-powered tattoo sensors could be further integrated with soft printed circuit board (PCB), enabling wireless control of everyday electronic devices such as house appliances and electronic robotic devices. Furthermore, a 4x4 multi-pixel bilayer array is demonstrated for tactile sensing capabilities.