A Freeze-Resistant, Highly Stretchable and Biocompatible Organohydrogel for Non-Delayed Wearable Sensing at Ultralow-Temperatures

Wearable electronics based on conductive hydrogels (CHs) easily suffer from prolonged response times, reduced wearing comfort, shortened service lives, and impaired signal accuracy in cold environments, because conventional CHs tend to freeze at subzero temperatures and lose their flexibility, adhesion, transparency, and conductivity, which will limit their applications in extreme environments. Inspired by the way psychrotolerant creatures and superabsorbent materials interfere with the hydrogen bonding networks of water, a freeze-resistant conductive organohydrogel (COH) is facilely fabricated. The synergy effect between charged polar terminal groups and a binary solvent system of water-ethylene glycol weakens the hydrogen bonding between water molecules and endows the COH with remarkable freezing tolerance (-78 degrees C). Additionally, the obtained COH is ultra-stretchable (approximate to 6185%), tough (9.2 MJ m-3), highly transparent (approximate to 99%), self-adhesive (10.2-27.8 kPa), and biocompatible. This versatile COH is assembled into a strain sensor and a well-designed bracelet electrocardiogram sensor. Benefiting from the exceptional low-temperature tolerance of the prepared COH, these devices exhibit fast response with delay-free signals even at -40 degrees C. Overall, this work proposes a strategy to develop multifunctional COHs for supporting human health in cold environments. A freeze-tolerant conductive organohydrogel is fabricated by in situ forming charged polar terminal groups and a water-ethylene glycol binary solvent system. The prepared organohydrogel is ultra-stretchable (approximate to 6185%), tough (9.2 MJ m-3), highly transparent (approximate to 99%), freeze-tolerant (-78 degrees C), self-adhesive (10.2-27.8 kPa) and biocompatible. It is applied to low-temperature adaptive wearable devices with delay-free signals even at -40 degrees C.image