Visualization and label-free quantification of microfluidic mixing using quantitative phase imaging

Abstract

Microfluidic mixing plays a key role in various fields, including biomedicine and chemical engineering. To date, although various approaches for imaging microfluidic mixing have been proposed, they provide only quantitative imaging capability and require exogenous labeling agents. Quantitative phase imaging techniques, however, circumvent these problems and offer label-free quantitative information about concentration maps of microfluidic mixing. We present the quantitative phase imaging of microfluidic mixing in various types of polydimethylsiloxane microfluidic channels with different geometries; the feasibility of the present method was validated by comparing it with the results obtained by theoretical calculation based on Fick's law.

Invited Article: Digital refocusing in quantitative phase imaging for flowing red blood cells

“…One criterion that is needed for cell based diagnostic applications is high throughput, which seems to be achievable by imaging flowing cells in a microfluidic device. QPI has been previously applied to imaging in microfluidics, ranging from monitoring microfluidic mixing 2 to sperm selection. 3 One experiment has shown cell imaging through turbid microfluidic channels using digital holography 4,5 with an emphasis on reducing the effect of turbidity.…”

Quantitative phase imaging of erythrocytes under microfluidic constriction in a high refractive index medium reveals water content changes

“…QPM has been previously applied to studies involving microfluidic devices as well. Recent studies associated with microfluidic mixing 20 and sperm selection 21 show that these microchips can be integrated into a QPM system to quantify dynamic changes. Additionally, another group of researchers utilized the random rolling motions of the cells in microfluidic channels to obtain tomographic projections without mechanical scanning 22 .…”