Microfluidic tailoring of the two-dimensional morphology of crimped microfibers

We synthesized uniform crimped microfibers with controlled dimensions using a microfluidic approach, whereby a liquid jet flows from a narrow channel into a wider channel. The liquid jet, sheathed by an immiscible non-reacting liquid, undergoes ultraviolet (UV)-initiated gelation upstream of the channel widening. At the channel widening, the reacting jet may buckle due to an axial compressive stress, and the transient buckled morphology is preserved in the structure of the resulting solid fiber as the gelation reaction rapidly goes to completion. We investigated the effects of different experimental conditions, such as flow rate, UV light position, concentration of photoinitiator and UV light intensity on controlling the morphology of the microfibers, and we observed that the degree of crimp in the microfiber is dependent mainly on the extent of reaction.