The small length scales in microfluidics enable viscosity measurements at high shear rates while simultaneously imaging the flow field using microscopy. We use particle tracking methods, including 3D holographic microscopy, to measure flow fields of non-Newtonian fluids and relate these flow fields to slit/capillary rheology measurements. The use of microfluidic rheology also enables viscosity measurements of small sample volumes, typically less than 100 µL.
The flow of viscoelastic fluids through microfluidic devices and capillaries can become unstable, making viscometric measurements and processing difficult. We study the conditions that lead to these instabilities for commercially relevant fluids, such as surfactant and polymer solutions. The viscoelastic flow is studied using various techniques including particle tracking methods, pressure measurements, and polarized light microscopy.
Protein Aggregation and Interfacial Kinetics
Minimizing aggregation of protein-based therapeutics under flow is essential for product quality. The need for improved understanding of the shear rates, surface chemistry, and interfacial kinetics that lead to aggregation motivates the development of improved experimental designs. Using microfluidic devices, we monitor the evolution of protein aggregation over time using microscopy and scattering techniques under various flow conditions.