Cell mechanical properties are a useful measure of phenotype that can be quantified by cell deformability. There is a lack of high-throughput methods to investigate the mechanical properties of large populations of individual cells. To address this need, we developed optical alignment deformation spectroscopy (OADS), a technique where hydrodynamic interactions between individual cells are used to create deformation. In OADS, a linear optical trap is used to align two incoming cells in a microfluidic cross-flow geometry, allowing hydrodynamic forces to induce a collision between cells at the stagnation point (see figure). After the interaction, the cells leave the stagnation point and a new pair of cells enters the trap. A convenient model cell to characterize OADS is the human erythrocyte because of its well-known mechanical properties. We fit deformation data of erythrocytes to a linear viscoelastic constitutive model (Voigt). This model incorporates a spring and dashpot in parallel, for the elastic (k) and viscous (η) parameters of the cell, respectively. Our measured values of k = 14.5 μN/m and η = 4.9 μN∗s/m compare favorably with literature values. Our results show OADS has potential as an accurate high-throughput individual cell mechanical cytometer.View Large Image | View Hi-Res Image | Download PowerPoint Slide
