Digital holography as a method for 3D imaging and estimating the biovolume of motile cells

Abstract

Sperm morphology is regarded as a significant prognostic factor for fertilization, as abnormal sperm structure is one of the most common factors in male infertility. Furthermore, obtaining accurate morphological information is an important issue with strong implications in zoo-technical industries, for example to perform sorting of species X from species Y. A challenging step forward would be the availability of a fast, high-throughput and label-free system for the measurement of physical parameters and visualization of the 3D shape of such biological specimens. Here we show a quantitative imaging approach to estimate simply and quickly the biovolume of sperm cells, combining the optical tweezers technique with digital holography, in a single and integrated set-up for a biotechnology assay process on the lab-on-a-chip scale. This approach can open the way for fast and high-throughput analysis in label-free microfluidic based "cytofluorimeters" and prognostic examination based on sperm morphology, thus allowing advancements in reproductive science.

Label-Free Quantitative Imaging of Sperm for In-Vitro Fertilization Using Interferometric Phase MicroscopyIVF, IMSI, ICSI, IPM, Holography, Imaging, Sperm

“…Their system utilizes optical tweezers to trap and rotate the cells as they flow through a microchannel, enabling holographic imaging of the sperm from multiple angles and the production of a tomographic 3D model. Aside from enabling highthroughput, imaging the live sperm in a microchannel allows the sperm to retain its natural shape, as opposed to the altered shapes produced when sperm adheres to a slide or is crushed under a coverslip [26,28].…”

Role of Arbitrary Intensity Profile Laser Beam in Trapping of RBC for Phase-imaging

“…Interdependency of phase-map extraction with optical thickness and hence computation of RI of the RBC is customarily done by using two suspension media of known RI. Procedures to decouple these entangled parameters is elucidated elsewhere [31,34,35,[39][40][41]43].…”

“…But in DHR, RBCs are made stationary by adhering them directly to a glass surface that can invoke perturbations from two facets -physical contact and their own weight which might alter their innate morphology. Digital holography in conjugation with OTs (HOT) has been reported for 3D shape evaluation of convex shape objects by observing cells along different directions [39][40][41][42]. Mohanty et al [43] have combined HOTs with quantitative phasemicroscopy for decoupling geometric thickness from RI.…”

Investigating the Swimming of Microbial Pathogens Using Digital Holography

“…Although this method was first described some twenty years ago [8], computing power has recently developed to the stage that DIHM can be routinely implemented in desktop machines. There are two distinct implementations of this method: a quantitative phase contrast method to assess the axial thickness of microscopic subjects [9,10,11]; and a method for three-dimensional localisation and imaging of objects [12,13,14,15]. This paper concentrates on the latter, and its application to microbial pathogens.…”