Ultrastretchable Strain Sensors and Arrays with High Sensitivity and Linearity Based on Super Tough Conductive Hydrogels

Biocompatible conductive hydrogels with intrinsic flexibility, high sensitivity, linearity and outstanding reliability are highly demanded for wearable devices or implantable sensors. Here we report novel tough conductive hydrogels composed of interpenetrating polyaniline (PANI) and poly(acrylamide-co-hydroxyethyl methyl acrylate) (P(AAm-co-HEMA)) networks. Intrinsic interactions between the conductive PANI network and the flexible P(AAm-co-HEMA) endowed hydrogels with outstanding strength and toughness to cyclic loadings. The conductive hydrogels show very high sensitivity (gauge factor 11) and outstanding linear dependence of sensitivity on strain. Strain sensors based on the conductive hydrogels demonstrate reliable detection of repeated large strains and subtle vibrations, including the movements of various human joints, pulses and voiceprints. Moreover, a prototype 2D sensor array is fabricated to sense strains or pressures in the two dimensions, which is promising for electronic skin, touchpads, biosensors, human-machine interfaces, biomedical implants, wearable electronic devices and so on.