Quantitative phase microscopy of red blood cells during planar trapping and propulsion


Red blood cells (RBCs) have the ability to undergo morphological deformations during microcirculation, such as changes in surface area, volume and sphericity. Optical trapping techniques have been widely used to study the micro-manipulation and deformation of RBCs. Optical waveguides can be used for this purpose, and are suitable for trapping, propelling and deforming large cell populations along the length of the waveguide. In this work we have combined quantitative phase microscopy (QPM) and waveguide trapping techniques to study changes in RBC morphology during planar trapping and transportation. By using interference microscopy, time-lapsed interferometric images of trapped RBCs were recorded in real-time and subsequently utilized to reconstruct optical phase maps. Quantification of phase differences before and after trapping, enabled study of the mechanical effects of optical forces exerted during planar trapping on RBCs. During planar trapping, the maximum phase values of RBCs were shown to decrease overall. Using high-resolution QPM, the phase values for two specific regions within RBCs were analyzed: the annular rim and the central donut. During planar trapping, the phase value of the annular rim decreases whereas it increases for the central donut. These changes correspond to a redistribution of hemoglobin content inside the RBC during trapping and subsequent transportation along the waveguide. This data was also used to quantify other changes in RBC morphology, showing an overall increase in surface area and a decrease in volume and sphericity of waveguide-trapped RBCs.

Contact details: 

Prof. D. S. Mehta

Department of Physics