Silver-nanowire-enhanced conductive hydrogels with high toughness and super sensitivity for character-recognizable writing screens and human motion monitoring

Flexible hydrogels have garnered extensive research interest due to the synergy of toughness, rapid response and strain sensitivity. However, their applications have been largely confined to conventional strain sensing for human motion monitoring, leaving broader interactive functionalities underexplored. Herein, flexible sensing material based on a nanocomposite (NC) hydrogel synthesized via a one-pot polymerization of nano-clay (Laponite XLS) and N-isopropylacrylamide (NIPAM). The incorporation of silver nanowires (AgNWs) as conductive additives leads to a significant enhancement in the hydrogel’s electrical conductivity. The optimized NC‑AgNWs hydrogel exhibits remarkable synergistic properties: a tensile strength of 12.95 MPa paired with an ultrahigh elongation at break of 1977 %, a compressive strength of 86.38 kPa at 80 % strain, and an electrical conductivity of ∼2.42 mS·cm⁻¹ . The material also demonstrates excellent cyclic durability and millisecond-scale response times (350 ms and 80 ms under 10 % tensile and 2 % compressive loading, respectively). Capitalizing on its strain-sensitive resistive behavior, we further engineered a flexible writing screen that converts machine-written characters into distinguishable resistance waveforms. Additionally, the hydrogel serves as a highly responsive strain sensor for monitoring human movements. This work not only advances the design of multifunctional conductive hydrogels but also highlights their potential as a dynamic human-computer interface to address growing information security challenges.