Lignin Eutectogel Smart Skins for Integrated Fast Communication, Cervical Posture Monitoring and Warning

Conductive hydrogels underpin multifunctional electronic skins, yet unifying sustainable processing, long‐term interfacial adhesion, and robust performance across extreme temperatures remains a central materials challenge for wearable sensing applications. This study presents a long‐term storable lignin eutectogel (LS/PAM/DES) synthesized via a facile one pot method. The eutectogel demonstrates remarkable stretchability, relatively high ionic conductivity, and reliable strain sensing performance. It remains soft and highly stretchable even at −20°C environment, and retains most of its mass, ionic conductivity, and tensile deformability but a more pronounced decrease in tensile strength after one month of ambient exposure, indicating its promise as a non‐volatile hydrogel alternative. The eutectogel can accurately capture motion signals from various body regions and enables rapid information input through a T9‐style keyboard interface. When integrated with a convolutional neural network (CNN)‐based classification framework, it enables automated recognition of predefined posture classes under the present controlled conditions. Moreover, an integrated device based on this eutectogel effectively evaluates sustained neck‐posture deviations beyond preset angular and temporal thresholds and activates corresponding visual warnings. This work demonstrates the proof‐of‐concept feasibility of wearable sensing, gesture‐based communication, cervical‐posture monitoring, and threshold‐based posture‐deviation warning using the LS/PAM/DES eutectogel.