Lignin reinforced tough, adhesive, and recoverable protein organohydrogels for wearable strain sensing under sub-zero temperatures.

Protein-based hydrogels with promising biocompatibility and biodegradability have attracted considerable interest in areas of epidermal sensing, whereas, which are still difficult to synchronously possess high mechanical strength, self-adhesion, and recoverability. Hence, the bio-polymer lignosulfonate-reinforced gluten organohydrogels (GOHLx) are fabricated through green and simple food-making processes and the following solvent exchange with glycerol/water binary solution. Ascribing to the uniform distribution of lignosulfonate in gluten networks, as well as the noncovalent interactions (e.g., H-bond) between them, the resultant GOHLx exhibit favorable conductivity (∼14.3 × 10-4 S m-1), toughness (∼711.0 kJ m-3), self-adhesion (a maximal lap-shear strength of ∼33.5 kPa), high sensitivity (GF up to ∼3.04), and durability (∼3000 cycles) toward shape deformation, which are suitable for the detection of both drastic (e.g., elbow and wrist bending) and subtle (e.g., swallowing and speaking) human movements even under -20 °C. Furthermore, the GOHLx is also biocompatible, degradable, and recoverable (by a simple kneading process). Thus, this work may pave a simple, green, and cheap way to prepare all-biomass-based, tough, sticky, and recoverable protein-based organohydrogels for epidermal strain sensing even in harsh environments.