Conductive Self-Healing Nanocomposite Hydrogel Skin Sensors with Antifreezing and Thermoresponsive Properties

Abstract

With growing interest in flexible and wearable devices, the demand for nature-inspired soft smart materials, especially intelligent hydrogels with multiple perceptions toward external strain and temperatures to mimic the human skin, is on the rise. However, simultaneous achievement of intelligent hydrogels with skin-compatible performances, including good transparency, appropriate mechanical properties, autonomous self-healing ability, multiple mechanical/ thermoresponsiveness, and retaining flexibility at subzero temperatures, is still challenging and thus limits their application as skinlike devices.Here, conductive nanocomposite hydrogels (NC gels) were delicately designed and prepared via gelation of oligo(ethylene glycol) methacrylate (OEGMA)-based monomers in a glycerol−water cosolvent, where inorganic clay served as the physical cross-linker and provided conductive ions. The resultant NC gels exhibited good conductivity (∼3.32 × 10 −4 S cm −1 , akin to biological muscle tissue) and an autonomously self-healing capacity (healing efficiency reached 84.8%). Additionally, such NC gels displayed excellent flexibility and responded well to multiple strain/temperature external stimuli and subtle human motions in a wide temperature range (from −20 to 45 °C). These distinguished properties would endow such NC gels significant applications in fields of biosensors, human−machine interfaces, and soft robotics.

Self-Healing and Highly Stretchable Hydrogel for Interfacial Compatible Flexible Paper-Based Micro-Supercapacitor

“…As revealed in Figure S10a, capacitance retention of the CV test is 97.59% from 0 • to 90 • , implying the excellent durability and mechanical robustness of the BPVA-Pluronic electrolyte-based MSC, as well as the excellent flexibility of the components which would not suffer severe decrease of the electrochemical performance under deformation [3]. Stability of electrochemical properties under multiple mechanical damages is the major challenge to develop durable MSC [46]. In order to overcome the defect of traditional substrate that self-healing ability is decreased by the compression deformation of the basement, cellulosic paper is selected as substrate of MSC [1,34].…”

Flexible Self‐Repairing Materials for Wearable Sensing Applications: Elastomers and Hydrogels

“…At present, the most important way to achieve the antifreezing and moisturizing properties of hydrogels is to use binary solvent system. The original water-soluble part is replaced by the low-temperature-resistant organic solvents, such as water/glycerol, [118,[137][138][139][140] water/ethylene glycol. [74,112,141,142] Ma et al designed a nanocomposite organic hydrogel, which was prepared from a hydrogel polymer network consisting of polyvinyl alcohol, phenylboronic acid-grafted alginate and polyacrylamide in a binary ethylene glycol (EG)/H 2 O solvent system by conformally coating a redox graphene oxide network.…”

“…At present, the most important way to achieve the antifreezing and moisturizing properties of hydrogels is to use binary solvent system. The original water‐soluble part is replaced by the low‐temperature‐resistant organic solvents, such as water/glycerol, [ 118,137–140 ] water/ethylene glycol. [ 74,112,141,142 ] Ma et al.…”

In-Situ Forming pH and Thermosensitive Injectable Hydrogels to Stimulate Angiogenesis: Potential Candidates for Fast Bone Regeneration Applications

“…Poly(VCL-co-UA), Poly(vinylcaprolactam) (PVCL) and Poly(N-isopropylacrylamide) (PNIPAM)-based microgels have been promising candidates in controlled drug delivery of anticancer drugs, such as, doxorubicin [19][20][21]. A combination of nanocomposite hydrogels in glycerol-water cosolvent (GW) gels have great potential to be used in biosensing, soft-robotics and artificial intelligence due to their electrical sensitivity towards environmental temperature changes [22,23]. A combination of tranexamic acid (TXA) and thermosensitive CS-β-GP (β-glycerophosphate) gel/spray has promoted nasal wound healing in the treatment of epistaxis [24].…”