Fully Bio-Based Gelatin Organohydrogels via Enzymatic Crosslinking for Sustainable Soft Strain and Temperature Sensing

초록

Developing soft materials that integrate mechanical compliance, functional responsiveness, and environmental sustainability is key for next-generation wearable and implantable electronics. Here, a sustainable, fully bio-based organohydrogel sensor made entirely from food-grade and biodegradable components, including gelatin, microbial transglutaminase (TG), and glycerol, prepared via a simple one-pot process under mild thermal conditions, is reported. In this system, TG enzymatically crosslinks gelatin chains into a robust covalent network, while glycerol enhances flexibility, stabilizes hydration, and facilitates proton conduction. The multicomponent system reveals a tunable network morphology governed by enzymatic crosslinking density. The resulting gels exhibit remarkable stretchability (up to 450%), linear strain sensitivity up to 300%, and a high gauge factor of 2.86-placing them among the top-performing hydrogel-based strain sensors to date. In addition to strain sensing, the material shows strong thermal responsivity (0.26 degrees C-1 in the 20-45 degrees C range) without being affected by variations in environmental humidity. Long-term electromechanical stability is demonstrated over 5000 cycles. Unlike conventional soft sensors that rely on synthetic polymers, fillers, or dopants, this platform entirely uses food-safe components and a simple one-pot process-offering a scalable and sustainable route to soft electronics. These findings establish enzyme-guided polymer engineering as a powerful tool for functional material design.

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