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CHARACTERIZING THE PHYSICAL PROPERTIES OF LIVING CELLS THROUGH MICROFLUIDIC IMPEDANCE SENSING
Title
CHARACTERIZING THE PHYSICAL PROPERTIES OF LIVING CELLS THROUGH MICROFLUIDIC IMPEDANCE SENSING.
Creator
Galpayage, Dona Kalpani Nisansala Udeni, Lau, Andy W.C., Du, Sarah E., Florida Atlantic University, Department of Physics, Charles E. Schmidt College of Science
Abstract/Description
The purpose of this research is to explore and investigate the biophysical properties of living cells using microfluidics based electrical impedance sensing (EIS) technique. It provides a non-invasive approach to detect label-free biological markers in the regulation of cellular activities even at a molecular level. We specifically focus on the development, testing, and theoretical modeling of electrical impedance spectroscopy for neuroblastoma cells and endothelial cells. First, we...
Show moreThe purpose of this research is to explore and investigate the biophysical properties of living cells using microfluidics based electrical impedance sensing (EIS) technique. It provides a non-invasive approach to detect label-free biological markers in the regulation of cellular activities even at a molecular level. We specifically focus on the development, testing, and theoretical modeling of electrical impedance spectroscopy for neuroblastoma cells and endothelial cells. First, we demonstrate that the EIS technique can be used to monitor the progressive mitochondrial fission/fusion modification in genetically modified human neuroblastoma cell lines. Our results characterize quantitatively the abnormal mitochondrial dynamics through the variations in cytoplasm conductivity. Secondly, we employ a real time EIS method to determine the biophysical properties of the junctions which join one endothelial cell with one another in a monolayer of endothelial cells. In particular, we examine the role of the protein, c-MYC oncogene, in the barrier function. Our results show that the downregulation of c-MYC oncogene enhances the endothelial barrier dysfunction associated with inflammation. Finally, we measure and find that the electrical admittance (the reciprocal of the impedance) of the monolayer of endothelial cellular networks exhibits an anomalous power law of the form, Y ∝ ωα, over a wide range of frequency, with the value of the exponent, α, depending on the severity of the inflammation. We attribute the power law to the changes of the intercellular electric permeability between neighboring endothelial cells. Thus, the inflammation gives rise to relatively smaller values of α compared to that of the no-inflammation group. Furthermore, we propose a simple percolation model of a large R-C network to confirm the emergent of power law scaling behavior of the complex admittance, suggesting that the endothelial network behaves as a complex microstructural network and its electrical properties may be simulated by a large R-C network.
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Date Issued
2020
PURL
http://purl.flvc.org/fau/fd/FA00013595
Subject Headings
Microfluidics, Impedance spectroscopy, Cells
Format
Document (PDF)
ELECTRICAL IMPEDANCE SENSING OF ERYTHROCYTES AND CYTOADHESION
Title
ELECTRICAL IMPEDANCE SENSING OF ERYTHROCYTES AND CYTOADHESION.
Creator
Liu, Jia, Du, Sarah E., Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
Abstract/Description
Electrical impedance of cells is a sensitive indicator of changes in cellular structure and biophysical characteristics. Integration of electrical impedance sensing in microfluidics can be a useful tool for characterization of blood cells for their disease state, such as sickle cell disease and malaria. The first part of this dissertation presents application of a microfluidics-based electrical impedance sensor for the study of sickle cell disease. Dynamic cell sickling-unsickling process of...
Show moreElectrical impedance of cells is a sensitive indicator of changes in cellular structure and biophysical characteristics. Integration of electrical impedance sensing in microfluidics can be a useful tool for characterization of blood cells for their disease state, such as sickle cell disease and malaria. The first part of this dissertation presents application of a microfluidics-based electrical impedance sensor for the study of sickle cell disease. Dynamic cell sickling-unsickling process of blood cells in response to cyclic hypoxia was measured. Strong correlation was found between the electrical impedance data and patients’ hematological parameters such as levels of sickle hemoglobin and fetal hemoglobin. In addition, application of electrical impedance spectroscopy in narrow microfluidic channel was used for label-free flow cytometry and non-invasive assay of single sickle cells under controlled oxygen level. We demonstrate the capability of this new technique in differentiating normal red blood cells from sickle cells, as well as sickled cells from unsickled cells, using normoxic and hypoxic conditions. The second part of this dissertation reports an application of electrical impedance sensing for the study of placental malaria. Testing conditions were optimized so that electrical impedance can be used for real time monitoring of different cellular and molecular level variations in this in vitro model of placental malaria. Impedance characteristics of cell proliferation, syncytial fusion and long-term response of BeWo cells to adhesion of infected erythrocytes were obtained and related to the immunostaining results and inflammatory cytokines measurements. Comparing to the conventional optical microscope-based methods, electrical impedance sensing technique can provide a label-free, real-time monitoring tool to study erythrocytes and cytoadhesion, and can further be extended to other disease models and cell types.
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Date Issued
2019
PURL
http://purl.flvc.org/fau/fd/FA00013389
Subject Headings
Microfluidics, Erythrocytes, Electric Impedance, Sickle cell disease, Malaria, Cell Adhesion
Format
Document (PDF)
Modeling and Experimental Study of Evaporation and Diffusion of Water Droplets on Foam Substrates
Title
Modeling and Experimental Study of Evaporation and Diffusion of Water Droplets on Foam Substrates.
Creator
Tian, Yining, Du, Sarah E., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description
The objective of this thesis is to develop a new experimental method to characterize the diffusion of water in polymer resins, based on the evolution in the volume of water droplets as a function of time. A finite element model is established to model the mass transport of water droplet through evaporation and diffusion processes. Diffusivity of water into polymer resins is then extracted by matching the volume variation of the simulated water droplet to the experimental results. Capability...
Show moreThe objective of this thesis is to develop a new experimental method to characterize the diffusion of water in polymer resins, based on the evolution in the volume of water droplets as a function of time. A finite element model is established to model the mass transport of water droplet through evaporation and diffusion processes. Diffusivity of water into polymer resins is then extracted by matching the volume variation of the simulated water droplet to the experimental results. Capability of this method is demonstrated by determining the diffusivity of water into void-free epoxy and epoxy samples with voids. Diffusion coefficient value obtained from this method agrees with data from conventional water immersion method. The significantly small scale of the water droplet (less than 10 microliter) allows rapid characterization of diffusivity in hours instead of months as typically required by the conventional immersion method. The method developed here provides a useful tool for rapid and effective characterization of diffusivity of water in polymer substrates and can be extended to other substances as well.
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Date Issued
2019
PURL
http://purl.flvc.org/fau/fd/FA00013270
Subject Headings
Polymers, Resins, Diffusion, Water, Evaporation--Experiments
Format
Document (PDF)