Formation of helical alginate microfibers using different G/M ratios of sodium alginate based on microfluidics

The helical structure is one of the most intriguing structures in nature; such an ingenious structure can be found from macromolecules to macroscopic areas, and the fabrication of helical structures has attracted research interest from mechanisms to applications. However, the fabrication of helical microfiber still remains a big challenge. In this study, a coaxial microfluidic device was made to continuously and controllably fabricate helical hydrogel microfibers with flexible shape by simply adjusting the flowrates. Various experimental conditions that can influence the diameter (d), pitch (p) and amplitude (A) of these formed coiled fibers were discussed. For the first time, the effects of G/M ratio of the alginates on the microfiber coiling phenomenon were examined. Additionally, magnetically responsive helical fibers were synthesized, and it is envisioned that hydrogel helical structure microfibers are highly versatile in different area, such as micro sensors, soft actuators and medical applications.