The mechanical stiffness of individual human cells can be a key parameter that reveals dysfunction of the cell. For example, malaria-infected red blood cells are known to be stiffer than uninfected cells and invasive cancer cells can be several times more deformable than healthy phenotypes. However, for biophysical properties to be more useful in biomedical and diagnostic settings, we will require methods for continuous biomechanical fractionation in high throughput, akin to size exclusion chromatography. Although separation by such parameters as size and density are commonly employed, few methods are available for high throughput separation by stiffness and no method for sorting by viscoelasticity. Moreover, because of the potential overlap of biophysical signatures of different cell types, to achieve purity in the separation may require the ability to fractionate cells such that subpopulations can be collected for which the biophysical values do not overlap. Towards these ends, we have created a microfluidic sorting technology that utilizes a combination of hydrodynamic and compressive forces to sort individual cells by biophysical properties. The objective of this research proposal is to create a high-throughput cell fractionation method based on the microfluidic technology that is sensitive to stiffness and viscosity, two orthogonal biophysical phenotypes of cells. The technology consists of a microchannel with periodical, diagonal constrictions that deform cells as they flow to modify their trajectory in a proportion to cell stiffness and viscosity. For example, cells that are stiffer are translated towards the upper part of the channel and cells that are softer migrate towards the bottom part of the channel such that outlets can continuously collect the sorted cells. By engineering channel geometry such as inter-ridge spacing, viscoelastic relaxation of cells can be emphasized, constituting a completely new sorting mechanism not previously utilized. Through computational understanding of channel hydrodynamics and stiffness-dependent trajectories of cells, outlets can be designed to specifically collect the sorted cells and thereby fractionate cells by stiffness. Also, by designin channels with different inter-ridge spacing, differences in cell relaxation rates can be exploited. In preliminary data, we show over 45-fold enrichment of cell types is possible in a label-free manner.

Public Health Relevance

We propose to develop a new microfluidic single enrichment method which can biophysically fractionate cells into multiple subpopulations of different stiffness. We will examine how various system parameters affect the fractionation of leukocytes and leukemia cells. These results will improve diagnostic analysis.

National Institute of Health (NIH)
National Institute of Biomedical Imaging and Bioengineering (NIBIB)
Exploratory/Developmental Grants (R21)
Project #
Application #
Study Section
Enabling Bioanalytical and Imaging Technologies Study Section (EBIT)
Program Officer
Lash, Tiffani Bailey
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Georgia Institute of Technology
Engineering (All Types)
Biomed Engr/Col Engr/Engr Sta
United States
Zip Code
Liu, Anna; Islam, Muhymin; Stone, Nicholas et al. (2018) Microfluidic generation of transient cell volume exchange for convectively driven intracellular delivery of large macromolecules. Mater Today (Kidlington) 21:703-712
Islam, Muhymin; Mezencev, Roman; McFarland, Brynn et al. (2018) Microfluidic cell sorting by stiffness to examine heterogenic responses of cancer cells to chemotherapy. Cell Death Dis 9:239
Tasadduq, Bushra; Lam, Wilbur; Alexeev, Alexander et al. (2017) Enhancing size based size separation through vertical focus microfluidics using secondary flow in a ridged microchannel. Sci Rep 7:17375
Islam, Muhymin; Brink, Hannah; Blanche, Syndey et al. (2017) Microfluidic Sorting of Cells by Viability Based on Differences in Cell Stiffness. Sci Rep 7:1997
Enten, Aaron; Yang, Yujia; Ye, Zihan et al. (2016) A Liquid-Handling Robot for Automated Attachment of Biomolecules to Microbeads. J Lab Autom 21:526-32
Wang, Gonghao; Turbyfield, Cory; Crawford, Kaci et al. (2015) Cellular enrichment through microfluidic fractionation based on cell biomechanical properties. Microfluid Nanofluidics 19:987-993