Microfluidic fabrication of highly stretchable and fast electro-responsive graphene oxide/polyacrylamide/alginate hydrogel fibers

The practical application of electro-responsive hydrogels is limited due to the slow response rate and the poor mechanical property. The electro-response rate of hydrogels can be improved by forming hydrogel fiber and adding graphene oxide (GO). Meanwhile, the incorporation of GO can also enhance the mechanical properties of hydrogels. However, the highly stretchable and fast electro-responsive hydrogel fibers are rarely reported at present. In this paper, graphene oxide/polyacrylamide/sodium alginate hydrogel fibers were prepared by microfluidic spinning and free radical polymerization. The mechanical properties, swelling properties and electro-responsive behaviors of the nanocomposite hydrogel fibers were investigated. The results show the nanocomposite hydrogel fibers could be very stretchable by adjusting GO and N,N-methylenebisacrylamide (BIS) contents. Besides, compared with hydrogel rods, the hydrogel fibers with diameter in microscale exhibit much faster swelling rate and electro-response rate. The thinner the hydrogel fiber is, the faster the electro-response rate is. This suggests that the highly stretchable and fast electro-responsive hydrogel fibers take us closer to the application of artificial muscle actuators.