Deep eutectic solvent infused silk fibroin gels for flexible touch sensing
Abstract
Silk fibroin hydrogels offer attractive biocompatibility and optical clarity but suffer from water-induced fragility, freezing, and biofouling. Here, regenerated silk networks are enzymatically cross-linked and subsequently exchanged with choline-chloride deep eutectic solvents (DESs) containing glycerol and ethylene glycol to create transparent, ionically conductive SF-DES gels. DES infusion preserves the protein's β-sheet framework while generating a more homogeneous nanonetwork and denser microstructure, increasing compressive modulus by up to 70% without altering protein concentration. The low volatility and depressed freezing points of DESs impart exceptional durability: the glycerol-based gel loses <5% mass under 37 °C, RH 35% airflow for 7 days, remains unfrozen at −80 °C, and the ethylene glycol-based gel maintains flexibility and conductivity of 0.013 mS cm−1 at −40 °C. Choline-based electrolytes inhibit growth of Escherichia coli and Staphylococcus aureus, mitigating microbial degradation. Leveraging this combination of mechanical resilience, environmental stability, ionic conductivity, and antimicrobial activity, bendable indium-free capacitive touch sensors are fabricated that achieve centimeter-scale position resolution and rapid gesture tracking. The study establishes DES infiltration as a general, aqueous-compatible route to robust, multifunctional protein gels, opening opportunities for sustainable wearable electronics, biomedical interfaces, and extreme-environment sensing.
- This article is part of the themed collection: Functional gel materials
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