Optical Coherence Tomography measurements of biofibril dispersions in flow-focusing

Abstract: Microfluidic spinning techniques have been used as a successful assembly process for biofibrils dispersed in a fluid. The dispersion flows through a microchannel and is focused by a sheath flow. In this way the topology and velocity of the dispersion in the core can be manipulated. By using Optical Coherence Tomography this topological development and velocities in the channel can be investigated and visualized. This is done for two different biofibrils: cellulose nano-fibrils and protein nano-fibrils. In both cases the geometry of the channel has been varied to investigate how this affects the flow of the dispersion. In the case of cellulose nano-fibrils the inlet angle of the side channels in the focus-section is varied. There is a thread forming for all angles tested, but with variations in shape. The velocity measurements also show differences in acceleration and deceleration behavior; indicating differences in inner morphology. For the protein nano-fibrils the distance between the side-channel inlets, in a device with two focus-sections, is shown to affect the wetting behavior of the dispersion.