Precise measurement of three-dimensional positions of transparent ellipsoidal particles using digital holographic microscopy.

The dynamic motions of various particles suspended in microscale flows are essential phenomena in the scientific and engineering fields. These motions can be precisely measured by using 3D quantitative flow visualization techniques. Moreover, most cells and particles in nature possess a nonspherical shape. Digital holographic microscopy (DHM) is employed to measure the 3D positional information of transparent ellipsoidal particles. Both in-plane and out-of-plane positional information are obtained by analyzing the distinctive light scattering from the microsized ellipsoidal particles. The performance of the 3D position measurement method is experimentally verified for ellipsoidal particles seeded in a planar surface and a microtube. This DHM technique exhibits promising potential in the dynamic analysis of ellipsoidal particles and cells suspended in various microscale fluid flows.