Hypothesis: Development of soft conductive materials has enabled the promising future of wearable electronics for motion sensing. However, conventional soft conductive materials typically lack robust adhesive and on-demand removable properties for a target substrate. Therefore, it is believed that the integration of superior mechanical properties, electrical conductivity, and tunable adhesive properties into hydrogels would support and improve their reliable sensing performance.
Experiments: A hydrogel ionic conductor composed of cationic micelles crosslinked in the polyacrylamide (PAM) network was designed and fabricated. The viscoelastic, mechanical, adhesion, electrical, and antimicrobial properties of the hydrogel were systematically characterized.
Findings: The developed ionic conductor possesses a range of desirable properties including mechanical performances such as excellent stretchability (>1100%), toughness, elasticity (recovery from 1000% strain), conductivity (2.72 S·m-1), and antimicrobial property, owing to the multiple non-covalent supramolecular interactions (e.g., hydrogen bonding, hydrophobic, and π-π/cation-π interactions) present in the cross-linked network. Meanwhile, the developed hydrogel is incorporated with different stimuli-responsive polymers and exhibits a tunable adhesive property (triggerable attachment and on-demand removable capabilities) in adapt to the surrounding environmental conditions (i.e., pH, temperature). With all these significant features, the resulting hydrogel ionic conductor serves as a proof-of-concept motion-sensing system with excellent sensitivity and enhanced reliability for the detection of a wide range of motions.
Keywords: Conductive hydrogel; Stimuli response; Strain sensor; Tunable adhesion.
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