Vertical focusing and cell ordering in a microchannel via viscoelasticity: Applications for cell monitoring using a digital holographic microscopy.

We demonstrate sheath-free vertical concentration and positioning of cells induced by fluid viscoelasticity in a rectangular channel. The high uniformity in depth position and the reduction in cell overlap eliminate out-of-focus blurring and increase detection sensitivity. Additionally, orientational ordering of red blood cells improves the monitoring and counting performance of an optical imaging system. As a proof of concept of vertical focusing and cell ordering, we demonstrate counting and monitoring of red blood cells flowing in a microchannel using phase-contrast holographic microscopy for quantitative phase imaging. [ABSTRACT FROM AUTHOR]