Single-Cell Density Mapping and Acoustic Self-Organization in Microfluidic Systems
(2025)- Abstract
- This thesis presents four interconnected studies showing methods for characterizing and separating cells based on their acoustic properties, with particular focus on isolating rare cells from blood samples.
The first study introduces a technique for single-cell density measurements using microcapillary-adapted density gradient centrifugation. Using fluorescent markers to visualize the density gradient and co-sedimenting cells with reference particles, we achieved density determinations with a precision
of 3.5 kg/m³ for individual yeast cells.
The second study develops a method to skim cells from packed whole blood. When blood is packed in an acoustic field, cells orient themselves within the packed blood according to their... (More) - This thesis presents four interconnected studies showing methods for characterizing and separating cells based on their acoustic properties, with particular focus on isolating rare cells from blood samples.
The first study introduces a technique for single-cell density measurements using microcapillary-adapted density gradient centrifugation. Using fluorescent markers to visualize the density gradient and co-sedimenting cells with reference particles, we achieved density determinations with a precision
of 3.5 kg/m³ for individual yeast cells.
The second study develops a method to skim cells from packed whole blood. When blood is packed in an acoustic field, cells orient themselves within the packed blood according to their acoustic properties, with red blood cells packing at the center of a microchannel and the plasma on the outside, while some cells migrate to interface of red blood cells and plasma. This phenomenon enables the separation of specific cells from the background of red blood cells by ’skimming’ them off the packed red blood cells. This method can be useful as a preliminary step for rare cell isolation.
The third study delves deeper into the mechanisms within the acoustically packed red blood cells, revealing four streaming rolls inside the packed cells and an additional four rolls in the surrounding blood plasma. It also demonstrates mechanisms of self-organization among other particles in the packed blood and during packing.
The fourth study extends cell characterization capabilities by combining isoacoustic focusing with density measurements. This dual approach enables determination of both density and compressibility for individual cells, providing a complete acoustic fingerprint that enhances discrimination between phenotypically similar cell populations.
Together, these studies form a workflow for blood sample analysis, even if they may appear disconnected at first glance. When analyzing whole blood—whether to identify specific white blood cell populations or to detect rare circulating tumor cells—the first step is to eliminate the dominant back-ground of red blood cells by acoustic packing and skimming mechanisms developed in Studies two
and three. Once the target cells have been separated, the density measurement approach from the first study can be applied to characterize them, either independently or in combination with the isoacoustic focusing and density-based separation concepts presented in Study 4. In this way, the four studies outline an integrated platform: acoustic enrichment through packing and skimming, followed by detailed biophysical phenotyping based on density and compressibility. This workflow has potential applications in liquid biopsy, where isolation and characterization of rare circulating tumor cells could inform cancer diagnosis and treatment monitoring. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/41a3bb9d-7e57-441e-b42b-981ac0156798
- author
- Soller, Richard LU
- supervisor
-
- Per Augustsson LU
- Ola Jakobsson LU
- opponent
-
- Dr. Winkler, Andreas, Leibniz-Institut für Festkörper- und Werkstoffforschung, Dresden, Germany.
- organization
- publishing date
- 2025
- type
- Thesis
- publication status
- published
- subject
- publisher
- Department of Biomedical Engineering, Lund university
- defense location
- Lecture Hall E:1406, building E, Ole Römers väg 3, Faculty of Engineering LTH, Lund University, Lund.
- defense date
- 2025-12-19 09:00:00
- ISBN
- 978-91-8104-777-6
- 978-91-8104-776-9
- language
- English
- LU publication?
- yes
- id
- 41a3bb9d-7e57-441e-b42b-981ac0156798
- date added to LUP
- 2025-11-25 10:27:49
- date last changed
- 2025-11-28 06:53:22
@phdthesis{41a3bb9d-7e57-441e-b42b-981ac0156798,
abstract = {{This thesis presents four interconnected studies showing methods for characterizing and separating cells based on their acoustic properties, with particular focus on isolating rare cells from blood samples.<br/>The first study introduces a technique for single-cell density measurements using microcapillary-adapted density gradient centrifugation. Using fluorescent markers to visualize the density gradient and co-sedimenting cells with reference particles, we achieved density determinations with a precision<br/>of 3.5 kg/m³ for individual yeast cells.<br/>The second study develops a method to skim cells from packed whole blood. When blood is packed in an acoustic field, cells orient themselves within the packed blood according to their acoustic properties, with red blood cells packing at the center of a microchannel and the plasma on the outside, while some cells migrate to interface of red blood cells and plasma. This phenomenon enables the separation of specific cells from the background of red blood cells by ’skimming’ them off the packed red blood cells. This method can be useful as a preliminary step for rare cell isolation.<br/>The third study delves deeper into the mechanisms within the acoustically packed red blood cells, revealing four streaming rolls inside the packed cells and an additional four rolls in the surrounding blood plasma. It also demonstrates mechanisms of self-organization among other particles in the packed blood and during packing.<br/>The fourth study extends cell characterization capabilities by combining isoacoustic focusing with density measurements. This dual approach enables determination of both density and compressibility for individual cells, providing a complete acoustic fingerprint that enhances discrimination between phenotypically similar cell populations.<br/>Together, these studies form a workflow for blood sample analysis, even if they may appear disconnected at first glance. When analyzing whole blood—whether to identify specific white blood cell populations or to detect rare circulating tumor cells—the first step is to eliminate the dominant back-ground of red blood cells by acoustic packing and skimming mechanisms developed in Studies two<br/>and three. Once the target cells have been separated, the density measurement approach from the first study can be applied to characterize them, either independently or in combination with the isoacoustic focusing and density-based separation concepts presented in Study 4. In this way, the four studies outline an integrated platform: acoustic enrichment through packing and skimming, followed by detailed biophysical phenotyping based on density and compressibility. This workflow has potential applications in liquid biopsy, where isolation and characterization of rare circulating tumor cells could inform cancer diagnosis and treatment monitoring.}},
author = {{Soller, Richard}},
isbn = {{978-91-8104-777-6}},
language = {{eng}},
publisher = {{Department of Biomedical Engineering, Lund university}},
school = {{Lund University}},
title = {{Single-Cell Density Mapping and Acoustic Self-Organization in Microfluidic Systems}},
url = {{https://lup.lub.lu.se/search/files/233897343/1_PDFsam_Richard_Soller_Single-Cell_Density_20251219_Pt1.pdf}},
year = {{2025}},
}