Super flexible sensor skin using liquid metal as interconnect

Abstract

Robust, flexible sensor skins have long been expected in robotic control. However, most flexible sensor skins are simply fabricated on flexible substrates with the sensor elements and electrical interconnects made from solid materials, which limits the flexibility of sensor skins. Here, we successfully incorporated liquid metal as interconnect to develop a super flexible sensor skin, which senses temperature and force simultaneously. The sensing element is PDMS elastomer mixed with 10% weight ratio multi-walled carbon nanotubes (MWNT). A eutectic liquid metal alloy (Galinstan: 68.5% Ga, 21.5% In, 10% Sn) material filled in microchannels as electrical interconnects. Thus, this skin can be bent dramatically without worrying about failure, which is a big issue for solid metal interconnects. The temperature coefficient of resistance (TCR) reaches 0.4%/degC, comparable to commercial resistance temperature detectors. The resistance change versus applied force was around 0.3%/KG.