(230i) High Throughput Microfluidic Platform to Characterize Flow Resistance of Trapped Deformable Particles

Measurement of pressure drop versus flow rate relations in microfluidic geometries is of broad interest in a variety of applications including rheology of complex fluids and mechanics of deformable particles. Experimental approaches to determine these relations in microscale geometries are limited. This is particularly evident for the case of trapped deformable particles where the non-circular cross-section of the microchannel, shape of the bounding walls and degree of occlusion, leads to a large control parameter space that can influence their flow resistance. Accessing this large parameter space requires methods that can determine pressure drop flow rate relations in a parallelized fashion. In this study, we investigate the use of co-flowing laminar streams in microfluidic parking networks to both trap deformable particles and measure their flow resistance. To validate this method, we fabricate microfluidic parking networks in which we vary the geometry, size and shape of the trap. Using Newtonian fluids, we quantify pressure drop flow rate relations for different trap geometries in a parallelized fashion and find that the data match well with the results from computational fluid dynamics simulations of single-phase flows. Next, we trap droplets in the microfluidic parking network and impose co-flowing laminar streams to measure flow resistance due to the occluding droplets. We find that the trap geometry and occlusion determine the strength of the gutter flows - which plays an important role in determining the flow resistance of the trapped droplets. Finally, we explore the capability of this approach in measuring the mechanical properties of giant unilamellar vesicles.