Inertial Manipulation and Transfer of Microparticles Across Laminar Fluid Streams

Abstract

A general strategy for controlling particle movement across streams would enable new capabilities in single-cell analysis, solid-phase reaction control, and biophysics research. Transferring cells across streams is difficult to achieve in a well-controlled manner, since it requires precise control of fluid flow along with external force fields or precisely manufactured mechanical structures. Herein a strategy is introduced for particle transfer based on passive inertial lift forces and shifts in the distribution of these forces for channels with shifting aspect ratios. Uniquely, use of the dominant wall-effect lift parallel to the particle rotation direction is explored and utilized to achieve controllable cross-stream motion. In this way, particles are positioned to migrate across laminar streams and enter a new solution without significant disturbance of the interface at rates exceeding 1000 particles per second and sub-millisecond transfer times. The capabilities of rapid inertial solution exchange (RInSE) for preparation of hematological samples and other cellular assays are demonstrated. Lastly, improvements to inline flow cytometry after RInSE of excess fluorescent dye and focusing for downstream analysis are characterized. The described approach is simply applied to manipulating cells and particles and quickly exposing them to or removing them from a reacting solution, with broader applications in control and analysis of low affinity interactions on cells or particles.

Engineering fluid flow using sequenced microstructures

“…5c). The preliminary results for solution exchange with this platform reach the highest achievable throughputs for cell separation compared with other state of the art techniques (B30-40 ml min À 1 for the cell stream) 22,23 . Performance of these systems is also comparable: By using our engineered sequence of pillars operating at 250 ml min À 1 upstream of a 7-fraction outlet (where the fluidic resistance of outlet fractions were designed to result in a specific distribution of outflow in each fraction), we were able to capture 96.0% (CV ¼ 14.6%) of 10 mm particles with a low contamination of background solution (10.8%, CV ¼ 0.19%) in outlet fraction 4, while recapturing a total of 83.8% (CV ¼ 0.20%) of the bead-free solution with only 3.85% (CV ¼ 0.10%) bead contamination in outlet fractions 5 and 6.…”

DNA-based highly tunable particle focuser

“…However, for genomic analysis from cells, target DNAs may be interfered with l-DNA sequence. In such situations, the l-DNA concentration can be significantly reduced with microfluidic media-exchange methods such as inertia-based approach 25 . In addition, the l-DNA sequence is available in the literature 26 , and thus, we expect that the sequence contamination by l-DNA can be effectively removed using the bioinformatics techniques that have been developed for metagenomics 27 .…”

Dynamics of particle migration in channel flow of viscoelastic fluids

“…The balance of two competing effects, the shear-gradient lift force (Asmolov 1999) and the wall repulsive force (Zeng et al 2005), determines the equilibrium position of the particles. These two forces scale differently but both depend on the Reynolds number (Matas et al 2004) and blockage ratio Gossett et al 2012). By properly designing the geometry of apparatus, the cross streamline migration can be used in cell and particle focusing, sorting, separation, filtration, enrichment and trapping.…”