Fig. 2

Applications of digital in-line holographic microscopy (DIHM) to track human erythrocytes and spermatozoa. a Lateral migration of hardened and normal erythrocytes in viscoelastic flows under different microfluidic conditions. Experimental setup for the microfluidic measurement (i). Digital image processing procedure: background subtraction (ii, scale bar = 10 μm), depth localization using a Tamura coefficient (TC) focus function (iii, scale bar = 10 μm), in-plane positioning (iv, scale bar = 10 μm), and 3D spatial distributions of spherical particles, hardened erythrocytes, and normal erythrocytes measured using DIHM (v-vii). Reprinted from ref. [149], Copyright 2017. b Measurement of 3D locations and orientations of erythrocytes using DIHM and deep learning techniques. Digital image processing procedure: raw hologram (i, scale bar = 20 μm), background subtraction (ii, scale bar = 20 μm), projection (iii, scale bar = 20 μm), depth localization using a gradient focus function (iv, scale bar = 5 μm), in-plane angle measurement (v, scale bar = 5 μm), and 3D positions and orientations of erythrocytes measured using DIHM (vi). Reprinted with permission from ref. [151], Copyright 2023, Elsevier B.V. c Transitions between different swimming patterns of a human spermatozoon. Hyper-activated (i, iv) and helical patterns (iii) are observed in a whole trajectory of the human spermatozoon (ii). Reprinted from ref. [152], Copyright 2012