Inertial microfluidic programming of microparticle-laden flows for solution transfer around cells and particles
Control of particles/cells and the surrounding fluid is enabling toward the purification of complex cellular samples, which still remains a bottleneck for point-of-care diagnostic devices. We explore a newly developed approach to engineer fluid stream motion while simultaneously controlling particles using inertial lift force. We use inertial flow deformations induced by sequences of simple pillar microstructures to control the fluid stream. Instead of iterative experimental procedures to identify optimal sequences of structures, we use software that numerically predicts the total deformation function for any pillar sequence. Using this program, we engineer the cross-stream translation of a fluid stream to achieve solution exchange around particles, where both the particles and fluid stream remain focused and can be extracted at high purity. An extraction device, called a pillar separation device, is then designed and validated with suspensions of rigid particles to identify optimal operating parameters. At a flow rate of 250 µL/min, up to 96 % beads and 70.5 % of an initial buffer stream inputted into the system can be collected downstream in separate outlets, respectively, with 10.9 % buffer and 0.3 % bead contamination. This device was further applied to a functionalized bead bioassay, achieving high-yield and continuous separation of 98 % of biotin-coated beads from 72.2 % of extra FITC-biotin. In a last study, we performed the extraction of 80 % of leukocytes from lysed blood, which validates our platform can be applied on living cells and used for various functions of cellular sample preparation.
KeywordsInertial microfluidics Pillar programming Particle fluid separation Solution exchange Sample preparation
This work is partially supported by NSF Grant #1307550. The authors would like to thank Dr. Oladunni Adeyiga for blood collection and all our volunteers for blood donation, Dr. Eric Tsang for his helpful advice with the Tecan Plate Reader, Dr. Ricky Chiu for his instructions on the Life Science UV/Vis spectrophotometer, Dr. M. Schibler and the California NanoSystems Institute Advanced Light Microscopy Core Facility for their assistance with the confocal studies.
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