Stretchable, self-healing, biocompatible, and durable ionogel for continuous wearable strain and physiological signal monitoring

Abstract

Electronic textiles (e-textiles) have great potential for use in wearable systems worn next to skin for continuous physiological monitoring, owing to their flexibility and conformability to the body. However, challenges exist in the long-term functionality and durability of these materials. This work presents a highly stretchable, self-healing, and biocompatible chloride-based ionogel fabricated from polymerization of thioctic acid, and 1-n-Butyl-3-methylimidazolium chloride ([BMIM]Cl) ionic liquid. With its adaptable mechanical properties and tunable viscosity by simple dilution, the ionogel precursor can be either cast into an ionogel film used for strain sensing applications up to 500% strain, or directly sprayed as a coating for e-textile electrodes for biopotential signal monitoring. The ionogel can reform at room temperature, demonstrating 73.5% stress recovery, and 84.8% modulus recovery after a 30-minute healing period. When used as a spray barrier coating on e-textiles, the ionogel displayed high resistance to abrasion, and reformed after adding ethanol to the surface. The electrical properties of the ionogel coated e-textiles satisfies the performance range desired for textile sensing electrodes. Further development and application of this ionogel material system can address long-term durability concerns by extending the usable lifetime of the sensors for wearable applications.