Flexible microfluidic fabrication of oil-encapsulated alginate microfibers

A unified microfluidic approach is presented for flexible fabrication of oil-encapsulated calcium alginate microfibers. The oil encapsulate phase was directly injected into the gelling alginate fiber, thus allowing the adjustable tuning of the encapsulate geometry ranging from spherical to prolate ellipsoid, plug-like and tubular shapes. Phase maps were developed that show the conditions required to achieve desired fiber morphologies with intended encapsulate phase ratio. We also show for very first time how oil encapsulates can be selectively grouped across the microfibers. A force-balance model, validated against a non-gelling system, was introduced to predict the size of spherical encapsulates.