Self-Helical Fiber for Glucose-Responsive Artificial Muscle

Abstract

A helical configuration confers a great advantage in artificial muscle due to great movement potential. However, most helical fibers are exposed to a high temperature to produce the coiled helical structure. Hence, thermoset polymercomposed hydrogels are difficult to fabricate as helical fibers due to their thermal degeneration. Here, we describe a self-helical hydrogel fiber that is produced without thermal exposure as a glucose-responsive artificial muscle. The sheath−core fiber was spontaneously transformed into the helical structure during the swelling state by balancing the forces between the untwisting force of the twisted nylon fiber core and the recovery force of the hydrogel sheath. To induce controllable actuation, we also applied a reversible interaction between phenylboronic acid and glucose to the selfhelical hydrogel. Consequently, the maximum tensile stroke was 2.3%, and the performance was six times greater than that of the nonhelical fiber. The fiber also exhibited tensile stroke with load and a maximum work density of 130 kJ/m 3 . Furthermore, we showed a reversible tensile stroke in response to the change in glucose level. Therefore, these results indicate that the self-helical hydrogel fiber has a high potential for use in artificial muscles, glucose sensors, and drug delivery systems.

Ultrastretchable, Adhesive, and Antibacterial Hydrogel with Robust Spinnability for Manufacturing Strong Hydrogel Micro/Nanofibers

“…To fulfill the diverse requirements depending on various applications, such as flexible electronic devices, [1] wound repair, [2] tissue-mimicking, [3] and soft robots, [4] tremendous efforts are Consequently, how to manufacture hydrogel fibers on a large scale as well as with robust mechanical properties is critical to be solved.…”

Progresses in Tensile, Torsional, and Multifunctional Soft Actuators

“…Kim group prepared a glucose‐responsive sheath‐core coiled artificial muscle fiber, using hydrogel coated polymer fiber based on a twist technique ( Figure A). [ 74 ] The reversible actuation was realized by volume expansion/contraction because of the phenylboronic acid in the sheath of the artificial muscle fiber (hydrogel part) by bonding/breaking with glucose molecules in water. This reversible sheath‐core coiled artificial muscle was prepared by coating hydrogel on a straight, twisted nylon fiber.…”

“…Reproduced with permission. [ 74 ] Copyright 2020, American Chemical Society. B) Schematic demonstration and optical images of anisotropic SNPP hydrogel actuator in poor solvent.…”

Bio-hybrid soft robots with self-stimulating skeletons

“…Muscle tissue is inherently complex, as it is simultaneously strong and fast, enabling a wide variety of movements through an efficient self-organization of its fiber bundles. Materials of synthetic origin still lack the ability to fully replicate these properties [13] , although recent advances based on pneumatic or dielectric actuators [14,15] , the incorporation of nanomaterials [16,17] or exploring alternative helical fiber configurations have been reported [18] . Even more, other features from biological tissues, such as self-healing, energy efficiency, power-to-weight ratio, adaptability or biosensing, are strongly desired but difficult to achieve with artificial soft materials [19] .…”