(532e) A Novel in-Line Fluidic Elastomer to Measure Particle Deformability

Microparticle deformation plays a crucial role in biological, environmental systems, and industrial systems. In biological systems, such as a blood vessel, the deformation of foreign particulates in the bloodstream directs their migration towards target sites.¹ In environmental applications, the deformation of microparticles affects sedimentation transport, while in industrial processes, particle deformation influences packing behavior.^2,3 Elastic microparticles are often used as templates to study the aforementioned phenomena. For instance, microgels are widely used in the biomedical sciences, both as scaffold materials and to encapsulate cells and biochemical moieties for further study, further illustrating the importance of elastic properties.

Traditional methods for measuring particle deformation include atomic force microscopy, application of osmotic pressure, and capillary micromechanics.4 These methods, however, are not well-suited for microparticles and hydrogels that have been fabricated by microfluidic techniques. They require particles to be collected after fabrication and removed from the generation device, leading to a discontinuous process that reduces the efficiency of particle characterization and slows the optimization process. Furthermore, ex situ characterization techniques, aside from the application of osmotic pressure, can measure only one particle at a time. Some of these processes are also destructive and could damage the particle, such as atomic force microscopy or nano indentation which requires contact with the particle. Microfluidic devices allow for continuous particle making of a wide variety of particle types; the high throughput, in-line, non-destructive nature of fluidics suggests such devices could also be used for particle characterization as well.

We use a microfluidic device to simultaneously fabricate and characterize hydrogel and elastic particles in situ. We fabricate soft particles using an emulsion-based pinch-off technique, allowing for the production of identical particles. Particles then flow through constrictions downstream, and their deformation is measured as a function of shear rate. Simulation-based research suggests that elastic particles may deform according to Taylor’s theory of small deformation for emulsion drops.^5,6 However, there is a lack of experimentally focused measurements of shear-induced particle deformation to verify these results in elastic particles. Thus, we independently measure the elastic properties of the particles using traditional methods in order to test the theoretical results. Our elastometer will improve both the ease and accuracy of continuous particle fabrication and characterization, benefitting multiple scientific disciplines.

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