Multifunctional\nConductive Hydrogel/Thermochromic\nElastomer Hybrid Fibers with a Core–Shell Segmental Configuration\nfor Wearable Strain and Temperature Sensors

Abstract

Flexible\nwearable sensors are emerging as next-generation tools\nto collect information from the human body and surroundings in a smart,\nfriendly, and real-time manner. A new class of such sensors with various\nfunctionality and amenability for the human body is essential for\nthis goal. Unfortunately, the majority of the wearable sensors reported\nso far in the literature were of a single function (mostly strain\nsensors) and just a prototype without thinking of continuous mass\nproduction. In this paper, we report a series of multifunctional conductive\nhydrogel/ thermochromic elastomer hybrid fibers with core–shell\nsegmental configuration and their application as flexible wearable\nstrain and temperature sensors to monitor human motion and body/surrounding\ntemperatures. Specifically, a conductive reduced-graphene-oxide-doped\npoly­(2-acrylamido-2-methyl-1-propanesulfonic acid-<i>co</i>-acrylamide (rGO-poly­(AMPS-<i>co</i>-AAm)) hydrogel and\na thermochromic elastomer containing silicon rubber and thermochromic\nmicrocapsules are chosen as strain-sensitive and thermosensitive materials,\nrespectively. A core–shell segmental structure is realized\nby programming the extrusion of either conductive hydrogel precursor\nsolution or a thermochromic elastomer prepolymer as a core layer via\ndual-core coaxial wet spinning. Depending on the assembly order and\nlength of the conductive hydrogel and the thermochromic elastomer,\nthe as-prepared hybrid fibers can be used for different purposes,\ni.e., human-motion monitoring, body or room temperature detection,\nand color decoration. The strategy described above, i.e., fabrication\nof core–shell segmental fibers via the wet-spinning method,\nis especially suitable for mass production in industry and can be\nfurther extended to fabricate flexible wearable devices with more\ncomponents and more functions such as transistors, sensors, displays,\nand batteries.