Multi‐Stimuli Responsive Viologen‐Crosslinked Eutectogels Derived From Natural Deep Eutectic Solvents for Information Security and Motion Detection

Stimuli-responsive soft materials capable of converting environmental and physiological stimuli into optical and electrical signals are highly attractive for information security, wearable sensing, and personalized healthcare management. Herein, we report biocompatible viologen-crosslinked eutectogels derived from poly(hydroxyethyl acrylate) (poly-HEA) and natural deep eutectic solvent composed of betaine and lactic acid. The eutectogels exhibit high transparency, excellent elasticity, and thermal stability, as well as robust adhesion on various substrates. The dynamic hydrogen-bonding network within the network endows the material with outstanding environmental stability and anti-freezing capability, maintaining stable optical performance under subzero conditions at -20°C. The eutectogels exhibit reversible chromic responses to multiple stimuli including electricity, UV light, and temperature. These optical responses enable reversible photopatterning and multilevel information encryption/decryption. We further demonstrate the functions of the eutectogels as a sensitive and stable strain sensor capable of monitoring diverse human motions, and even subtle physiological heartbeat signals. In addition, the strain-induced electrical outputs can also be further translated into Morse code for information transmission.