Cell separation based on size and deformability using microfluidic funnel ratchets

Abstract

The separation of biological cells by filtration through microstructured constrictions is limited by unpredictable variations of the filter hydrodynamic resistance as cells accumulate in the microstructure. Applying a reverse flow to unclog the filter will undo the separation and reduce filter selectivity because of the reversibility of low-Reynolds number flow. We introduce a microfluidic structural ratchet mechanism to separate cells using oscillatory flow. Using model cells and microparticles, we confirmed the ability of this mechanism to sort and separate cells and particles based on size and deformability. We further demonstrate that the spatial distribution of cells after sorting is repeatable and that the separation process is irreversible. This mechanism can be applied generally to separate cells that differ based on size and deformability.

On-chip sample preparations for Point-of-Care cellular analysis of blood

“…Reverse--flow filtration provides another concept to prevent clogging and increase the life time of filtration units. McFaul and co-workers fabricated a microratchet array and employed an oscillatory flow to selectively regenerate the pores blocked by larger and less deformable cells [20] (Figure 1v). …”

Optical particle sorting on an optofluidic chip

“…The ability to do this sorting on chip is ideal since it requires less handling of the sample and allows for smaller sample sizes. Previously reported sorting schemes involve optical [1][2][3], magnetic [4,5], electrical [6,7], acoustic [8,9] or mechanical [10][11][12] methods of separating objects by size or index, with sorting efficiencies ranging from 75% to 100%. Some of these options require an aspect of detection before separation [4,13], adding unwanted complexity.…”

Whole-blood sorting, enrichment and in situ immunolabeling of cellular subsets using acoustic microstreaming

“…These technologies typically require pre-processed samples and cannot handle the physical properties and complex populations inherent in whole blood [6][7][8][9][10] . They are limited to either diluted 11,12 or lysed blood 13,14 , and in some cases, density based centrifugation to reduce blood complexity and cell-cell interaction [15][16][17][18][19][20][21] . The microfluidic cell sorting technologies that can handle whole blood, in general fall into two categories: label free sorting based on physical characteristics of the target cells or biomarker labeling.…”