Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published August 5, 2021 | Published + Supplemental Material
Journal Article Open

Microscopic Object Classification through Passive Motion Observations with Holographic Microscopy

Abstract

Digital holographic microscopy provides the ability to observe throughout a volume that is large compared to its resolution without the need to actively refocus to capture the entire volume. This enables simultaneous observations of large numbers of small objects within such a volume. We have constructed a microscope that can observe a volume of 0.4 µm × 0.4 µm × 1.0 µm with submicrometer resolution (in xy) and 2 µm resolution (in z) for observation of microorganisms and minerals in liquid environments on Earth and on potential planetary missions. Because environmental samples are likely to contain mixtures of inorganics and microorganisms of comparable sizes near the resolution limit of the instrument, discrimination between living and non-living objects may be difficult. The active motion of motile organisms can be used to readily distinguish them from non-motile objects (live or inorganic), but additional methods are required to distinguish non-motile organisms and inorganic objects that are of comparable size but different composition and structure. We demonstrate the use of passive motion to make this discrimination by evaluating diffusion and buoyancy characteristics of cells, styrene beads, alumina particles, and gas-filled vesicles of micron scale in the field of view.

Additional Information

© 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). Received: 1 July 2021; Revised: 31 July 2021; Accepted: 1 August 2021; Published: 5 August 2021. We thank Manuel Bedrossian for the gas vesicle and alumina recordings and Louis Sumrall for the polystyrene and S. epidermidis recordings. Funding: The work described in this paper was performed in part at the Jet Propulsion Laboratory, California Institute of Technology under contract with the National Aeronautics and Space Administration and at PSU under a contract from the Jet Propulsion Laboratory, California Institute of Technology and from NSF MRI grant # 1828793. Author Contributions: Conceptualization, C.L. and J.N.; methodology, J.N.; software, all; validation, J.N.; formal analysis, D.R., C.L. and J.N.; resources, J.N.; data curation, C.L.; writing-original draft preparation, C.L.; writing-review and editing, J.N.; visualization, all; supervision, J.N.; project administration, J.N. and C.L.; funding acquisition, J.N. and C.L. All authors have read and agreed to the published version of the manuscript. Institutional Review Board Statement: Not applicable. Informed Consent Statement: Not applicable. Data Availability Statement: The raw holograms for the datasets used here are deposited in a public depository at Data Dryad, https://doi.org/10.5061/dryad.n02v6wwxj (accessed on 5 August 2021). Other data are available from the authors upon request.

Attached Files

Published - life-11-00793.pdf

Supplemental Material - life-11-00793-s001.zip

Files

life-11-00793-s001.zip
Files (66.6 MB)
Name Size Download all
md5:99374478a4b63f3c7a22feb3893014d6
64.1 MB Preview Download
md5:dff0ad8c121fb0facf3effa874c95dff
2.5 MB Preview Download

Additional details

Created:
August 22, 2023
Modified:
October 23, 2023