Three-Dimensional Holographic Refractive-Index Measurement of Continuously Flowing Cells in a Microfluidic Channel
Author(s)Sung, Yongjin; Lue, Niyom; Hamza, Bashar; Martel, Joseph; Irimia, Daniel; Choi, Wonshik; Yaqoob, Zahid; Dasari, Ramachandra Rao; So, Peter T. C.; ... Show more Show less
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The refractive index of biological specimens is a source of intrinsic contrast that can be explored without any concerns of photobleaching or harmful effects caused by extra contrast agents. In addition, the refractive index contains rich information related to the metabolism of cells at the cellular and subcellular levels. Here, we report a no-moving-parts approach that provides three-dimensional refractive-index maps of biological samples continuously flowing in a microfluidic channel. Specifically, we use line illumination and off-axis digital holography to record the angular spectra of light scattered from flowing samples at high speed. Applying the scalar diffraction theory, we obtain accurate refractive-index maps of the samples from the measured spectra. Using this method, we demonstrate label-free three-dimensional imaging of live RKO human colon cancer cells and RPMI8226 multiple myeloma cells, and obtain the volume, dry mass, and density of these cells from the measured three-dimensional refractive-index maps. Our results show that the reported method, alone or in combination with the existing flow cytometry techniques, shows promise as a quantitative tool for stain-free characterization of a large number of cells.
DepartmentLincoln Laboratory; Massachusetts Institute of Technology. Department of Biological Engineering; Massachusetts Institute of Technology. Department of Chemistry; Massachusetts Institute of Technology. Department of Mechanical Engineering; Massachusetts Institute of Technology. Laser Biomedical Research Center
Physical Review Applied
American Physical Society
Sung, Yongjin, Niyom Lue, Bashar Hamza, Joseph Martel, Daniel Irimia, Ramachandra R. Dasari, Wonshik Choi, Zahid Yaqoob, and Peter So. “Three-Dimensional Holographic Refractive-Index Measurement of Continuously Flowing Cells in a Microfluidic Channel.” Physical Review Applied 1, no. 1 (February 2014).
Author's final manuscript