A synergistically designed strain-insensitive conductive hydrogel with humidity-adaptivity supporting sustained functional durability

While employing hydrogels as conductive interconnects in flexible electronics, two intrinsic challenges require comprehensive solutions: performance degradation resulting from water evaporation and functional instability caused by strain-induced resistance increase. Thus, we integrate hygroscopic lithium bromide (LiBr) directly into hydrogel polymerization and exploit its multifaceted characteristics to develop a conductive hydrogel with humidity-adaptive water retention and strain-insensitivity. The synthesis is guided by the idea of "less is more", characteristics of acrylamide monomers (Aam), the silane coupling agent, and LiBr are synergistically leveraged to architect a hierarchical network comprising a primary backbone and dual-dynamic crosslinking. The prepared hydrogel possesses concomitant properties of ionic conductivity, softness, stretchability, and anti-freezing. Moreover, ionic and electronic hybrid conductivity (∼0.21 S cm^-1), an ultralow gauge factor (∼0.29) within a work strain range of 150% and electrical hysteresis (∼0.19%) are imparted via the incorporation of conductive additives. Cyclic tensile strain (10 000 cycles), prolonged exposure under fluctuated humidity conditions over 6 months (20%-50% fluctuated relative humidity), and low-temperature storage (-56 °C) were conducted to verify the sustained functional maintenance. The conductive hydrogel was practically qualified as a conductive interconnect for power supply and signal transmission. The results unfold a promising prospect of the conductive hydrogel with long-term reliability as a conductive interconnect.