Soft and Stretchable\nLiquid Metal–Elastomer\nComposite for Wearable Electronics

Abstract

Soft devices, especially capacitive stress (or strain)\nsensors,\nare important for applications, including wearable medical monitoring,\nelectronic skin, and soft robotics. The incorporation of liquid metal\nparticles (LMPs) into highly deformable elastomers as inclusions ameliorates\nthe mechanical compliance caused by a rigid filler. The high dielectric\nconstant and liquid feature of LMPs are suitable for soft sensors\nwith high sensitivity and a large real-time dynamic detection range.\nHere, a class of LM–elastomer composites are introduced with\nelastic and high dielectric properties, making them uniquely suitable\nfor the application of soft stress sensors. The prepared stretchable\nsoft stress sensor can detect the bending degree of the finger, monitor\nphysiological signals in real time, and distinguish the vibration\nfrom the pronunciation of different letters. The nanoscale X-ray computational\ntomography (nano-CT) measurements indeed detect the changes of LMPs\nunder stress, i.e., LMPs in the matrix distribute from uneven to relatively\nuniform, agglomerate, and even connect each other to have a conduction\npath in the composition with high LMP contents, which cause the changes\nin the physical properties of devices under operation. The cognition\nof LMP changes in composites under stress is instructive for promoting\ntheir further applications in the field of soft devices.