Continuous fabrication of near-infrared light responsive bilayer hydrogel fibers based on microfluidic spinning

Abstract

Hydrogel microfibers with inhomogenous structure can achieve some complex motions such as bending, folding and twisting. So it can be applied to soft actuators, soft robots and micropumps. In this paper, continuous bilayer hydrogel fibers in which one layer is calcium alginate hydrogel and the other is linear poly(N-isopropylacrylamide) (PNIPAM)/calcium alginate/graphene oxide (GO) semi-interpenetrating hydrogel were prepared based on microfluidic spinning method. The results show that the bilayer hydrogel fibers have particular porous internal structures of semi-IPN hydrogels and the pore size becomes smaller with the increase of GO content. Besides, the bilayer hydrogel fibers can bend response to the temperature and near-infrared (NIR) light. The diameter of the hydrogel fibers can be tuned by changing the flow rate of spinning fluid and the take-up velocity of winding device.

Preparation of a Hydrogel Nanofiber Wound Dressing

“…Whereas the spinning of the PVA/alginate resulted in a homogeneous fibrous layer with no defects, the PVA/gelatin fibrous layer had a fibrous structure with the presence of minor droplet defects that caused the fibrous layer to adhere to the underlying spunbond layer and the tearing of the layer during subsequent handling. In both cases, however, there is a shift in productivity, as fiber layers for the preparation of hydrogel fibers are currently only produced in small quantities [ 34 , 35 , 36 ].…”

“…During the study, a semi-industrial production of fiber layers was performed. This is an improvement over previous studies that produced only a small amount of fibers [34][35][36]. The fiber layers produced from the PVA/gelatin and PVA/alginate blends were investigated so as to determine the time required to crosslink the gelling component, i.e., the gelatin and the alginate, which resulted in the selection of 4 h of crosslinking.…”

Microfluidic elaboration of polymer microfibers from miscible phases: Effect of operating and material parameters on fiber diameter

“…On the other hand, the diameter increased with an increase in the flow rate of Φc, because of the widening of the jet due to the increase in the volume of Φc injected. [31][32][33][34] To observe the overall impact of the flow rate on the fiber diameter, the effect of Qs/Qc on the fiber diameter instead of individual flow rates was studied using PEG 300 as Φs. In…”

Large-Scale Spinning Approach to Engineering Knittable Hydrogel Fiber for Soft Robots

“…Nevertheless, only limited methods have been developed to produce hydrogel fiber actuators with simple deformations and unsatisfactory mechanical properties. ,− ,− There is a great need to develop efficient fabrication strategies to deterministically balance relationships between production methods and stimuli-responsive properties of materials and to retain their structural integrity during the manufacturing of structures of higher complexity. For the production of a hydrogel fiber, the solidification of a pregel solution needs to be designed in a way that it either happens outside the nozzle such as in electrospinning, , direct ink writing, and draw spinning or is isolated from the nozzle wall with a thin layer of solvent or air as in microfluidic spinning ,− to cast a 1D fiber. However, the aforementioned methods generally need immediate solidification during either physical processes or rapid chemical cross-linking reactions to maintain the shape of the 1D fiber.…”

“…Moreover, balancing the mechanical strength and stimuli-responsive performance is yet another challenge. Most hydrogel fibers with fast actuation performance are vulnerable to breakdown even upon low applied strain states, far from the requirement of manufacturing into desired stimuli-responsive structures, ,− limiting the further practical application of fiber actuators in complicated and wearable soft robotic systems.…”