(161c) A Library of Soft Particles for the Study of Lateral Migration in Low Reynolds Number Flow

The cross stream distribution of suspension components in pressure-driven flow in a channel depends on a range of factors, including particle size, shape, deformability, volume fraction, and Reynolds number¹. However, how each of these factors results in lateral migration is not well understood. In this work, we attempt to elucidate the roles of particle deformability and shape on lateral migration in low Reynolds number, pressure-driven channel flows through the use of model suspensions. Deformable, uniformly gelled alginate microspheres, particles with soft cores, and capsules, all with a broad range of deformabilities, were generated using a modified flow-focusing microfluidic device. Particle deformability was then quantified using capillary micromechanics in a tapered capillary². Average particle shear moduli range from 6 ± 1 kPa to 26 ± 8 kPa for the solid microspheres and from 0.6 ± 0.1 kPa to 3.1 ± 0.5 kPa for the particles with soft cores. An assortment of non-spherical alginate particles was also generated by allowing alginate emulsion drops to fall into an external bath containing crosslinking ions³. By changing the properties, e.g. viscosity, of the bath, the shapes of the resulting particles were altered. This library of particles is currently being used for lateral migration studies in long channels, the results of which will be discussed.

References:

(1) Kumar, A. and Graham, M. D. Soft Matter, 2012, 8, 10536.

(2) Guo, M. and Wyss, H. M. Macromol. Mater. Eng. 2011, 296, 223â??229.

(3) Hu, Y.; Wang, Q.; Wang, J.; Zhu, J.; Wang, H.; Yang, Y. Biomicrofluidics. 2012, 6, 026502.