Ultra-anti-freezing robust hydrogel snesor

Abstract

Although hydrogel sensors have broad application prospects in wearable devices, biomedical electronic skin, human–computer interaction and other fields, the hydrogel sensor with the synergy of robust mechanical behaviors, super freeze-resistant ability and signal output stability still remain challenged. To overcome the challenge, here, a novel hydrogel sensor AICG were developed using polyvinyl alcohol (PVA), glycidyl trimethyl ammonium chloride (EPTAC), polyethyleneimine (PEI) and ethylene glycol (EG). The effects of PVA, PEI, EPTAC and EG contents in AICG hydrogel on mechanical properties were systematically investigated. The notably boosted mechanical properties (antibreakage performance, fatigue-resistant ability) and super freeze-resistant performance are primarily ascribed to the superhydrogen-bond networks of PVA with PEI, EPTAC and EG. The hydrogel is so strong that it can load a 60 Kg boy and endure super low temperature (−120 ℃). Besides rendering AICG hydrogel good conductivity (5.56 mS·cm⁻¹), EPTAC was used to graft it on the PVA/PEI macromolecular chains of AICG hydrogel via ring-opening reaction of EPTAC, thus impeding the leakage of EPTAC from the hydrogel as much as possible and improving conductive stability. On being used a sensor, it can accurately detect human joint movements and simulate electronic skin due to high sensitivity and stable signal output ability. It is expected that this study can provide valuable information for the design and fabrication of the hydrogel sensor with desired high performances.