Generation of alginate microfibers with a roller-assisted microfluidic system

This work describes a convenient microfluidic strategy with a simple and minimal-requirement design for the generation of uniformly-sized alginate gel fibers with diameters one order of magnitude smaller than those formed in conventional methods. Different from common microfluidic methods, our system contains a single microchannel through which alginate solutions are transported and squeezed into a calcium chloride solution. Ca2+ ions immediately cross link the alginate solution into a gel state that is collected with a rotor. We use microchannels to define the initial size of the alginate fibers and a roller to further reduce the fiber size (diameter) by one order of magnitude down to similar to 1 mu m. The size of the formed fibers can be well controlled by adjusting the corresponding parameters, and be predicted with a simple equation. In addition, various functional materials (colloidal particles, bacteria and nanoparticles) have been encapsulated into the gel fibers with this technique.