On-chip fabrication and magnetic force estimation of peapod-like hybrid microfibers using a microfluidic device

Combining microfluidic methods for generating microdroplets and spinning microfibers, a novel type of alginate hybrid microfiber encapsulating different microdroplets is fabricated for various applications such as cell culture, tissue engineering and drug release. Traditional fabrication methods mainly depend on the microfluidic structure, so an effective method that uses microfluidic solution flow rates to control the generation of hybrid microfibers has not yet been developed. In this paper, we fabricate a microfluidic flow-focusing device with a long gelation microchannel to encapsulate magnetic oil microdroplets (MOMs) into alginate microfibers. We establish a hybrid microfiber generation model for this fabrication method based on limited flow rate to control microfiber width, MOM diameter and the distance between consecutive MOMs. We also calculate the magnetic force acting on a single MOM by measuring the distance and the MOM is deflected by disk magnets with respect to time in the long gelation microchannel. The magnetic forces acting on the microfibers can be further calculated by counting the number of encapsulated MOMs. The developed method has great potential for quantitative fabrication of diverse hybrid microfibers encapsulating a variety of magnetic hydrophobic microdroplets with estimated magnetic forces. Such magnetic hybrid microfibers are attractive for use in higher order alginate microfiber assemblies and dual drug delivery systems.