Current Search: Impedance spectroscopy (x)
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(1 - 7 of 7)
- 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
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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.
Show less - Date Issued
- 2020
- PURL
- http://purl.flvc.org/fau/fd/FA00013595
- Subject Headings
- Microfluidics, Impedance spectroscopy, Cells
- Format
- Document (PDF)
- Title
- Evaluation of orientation and formulation effects on the impedance of naval special hull treatments.
- Creator
- Mann, Kristina Marie., Florida Atlantic University, Granata, Richard D., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
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This research used Electrochemical Impedance Spectroscopy (EIS) as a non-destructive technique to evaluate coating performance and determine the electrochemical characteristics of Special Hull Treatments (SHT). The evaluation of the SHT system provided information on its corrosion resistance and cathodic protection-influencing characteristics. The coating's impedance was analyzed while exposed to ambient versus 4.5 MPa pressures and immersion times of 1 to 9 days in seawater. Eleven specimen...
Show moreThis research used Electrochemical Impedance Spectroscopy (EIS) as a non-destructive technique to evaluate coating performance and determine the electrochemical characteristics of Special Hull Treatments (SHT). The evaluation of the SHT system provided information on its corrosion resistance and cathodic protection-influencing characteristics. The coating's impedance was analyzed while exposed to ambient versus 4.5 MPa pressures and immersion times of 1 to 9 days in seawater. Eleven specimen types were evaluated based on coating seam orientation and composition. The data support the conclusion that there was no effect on impedance values and phase shifts due to orientation, formulation, pressure values or immersion time. However, temperature increase above 30° was shown to decrease the impedance values of the SHT specimens.
Show less - Date Issued
- 2001
- PURL
- http://purl.flvc.org/fcla/dt/12840
- Subject Headings
- Hulls (Naval architecture), Impedance spectroscopy
- Format
- Document (PDF)
- Title
- Mechanistic study of chromate adhesion enhancement on aluminum 2024-T3 alloy.
- Creator
- Simmons, Ronald M., Florida Atlantic University, Granata, Richard D., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
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This research investigates the influence of chromate, as a conversion coating and as an inhibitor pigment, on the adhesion of epoxy coatings to an aluminum substrate. Epoxy coatings, with and without strontium chromate (SrCrO4) inhibitor pigment, are prepared according to manufacturers' specifications on AA2024-T3 substrates, with and without chromate conversion coatings. Specimens are exposed in an environmental chamber, cycling between high and low humidity conditions. After exposure,...
Show moreThis research investigates the influence of chromate, as a conversion coating and as an inhibitor pigment, on the adhesion of epoxy coatings to an aluminum substrate. Epoxy coatings, with and without strontium chromate (SrCrO4) inhibitor pigment, are prepared according to manufacturers' specifications on AA2024-T3 substrates, with and without chromate conversion coatings. Specimens are exposed in an environmental chamber, cycling between high and low humidity conditions. After exposure, specimens are evaluated using Electrochemical Impedance Spectroscopy (EIS), ASTM D3359 cross-cut tape test, and an Environmental Scanning Electron Microscope. From the evaluation it was determined that under these exposure conditions chromate does not increase the adhesive strength between the aluminum substrate and the epoxy coating system, but does provide corrosion inhibition. Regardless of the pretreatment or the coating system, the coating fails at the interface between the substrate and the coating.
Show less - Date Issued
- 2001
- PURL
- http://purl.flvc.org/fcla/dt/12860
- Subject Headings
- Chromium compounds, Aluminum alloys, Impedance spectroscopy
- Format
- Document (PDF)
- Title
- Characterization of nickel electrodes for secondary batteries by means of electrochemical impedance spectroscopy.
- Creator
- Nenov, Krassimir Petrov., Florida Atlantic University, Lipka, Stephen M., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
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An automated procedure for integrated cycling and electrochemical impedance spectroscopy (EIS) testing of nickel sinter individualized pressure vessel electrodes for secondary nickel/hydrogen batteries was developed. Nickel electrodes from three major U.S. manufacturers were cycled under various conditions. The condition of the electrodes was monitored using both EIS and traditional electrochemical methods. In order to establish relationships between the status of the electrodes and the...
Show moreAn automated procedure for integrated cycling and electrochemical impedance spectroscopy (EIS) testing of nickel sinter individualized pressure vessel electrodes for secondary nickel/hydrogen batteries was developed. Nickel electrodes from three major U.S. manufacturers were cycled under various conditions. The condition of the electrodes was monitored using both EIS and traditional electrochemical methods. In order to establish relationships between the status of the electrodes and the acquired impedance spectra, various cycling and electrode parameters were analyzed and compared with the EIS data. Nonlinear least squares (NLS) regression was used for analysis of the impedance data. An equivalent circuit was developed which produced good correlation with the impedance data at all states-of-charge and discharge rates. Problems with the experimental procedure which limit the validity of EIS testing were discussed.
Show less - Date Issued
- 1991
- PURL
- http://purl.flvc.org/fcla/dt/14777
- Subject Headings
- Impedance spectroscopy, Electrochemical analysis, Electric batteries--Electrodes
- Format
- Document (PDF)
- Title
- Application of electrochemical impedance spectroscopy as a non-destructive technique to characterize and detect degradation of carbon/nylon, 6 composites in aqueous environments.
- Creator
- Haniyur, Ravishankar V., Florida Atlantic University, McIntyre, Jack F.
- Abstract/Description
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Experiments were conducted to investigate the degradative effects of ambient and high pressure aqueous environments on unidirectional carbon fiber nylon (AS4/nylon 6) composites. Electrochemical impedance spectroscopy (EIS) was selected for development as a non-destructive method to characterize the degradation phenomena in carbon/nylon composites as result of moisture absorption. EIS data was collected for composites and neat resins as a function of immersion time in ambient and pressurized ...
Show moreExperiments were conducted to investigate the degradative effects of ambient and high pressure aqueous environments on unidirectional carbon fiber nylon (AS4/nylon 6) composites. Electrochemical impedance spectroscopy (EIS) was selected for development as a non-destructive method to characterize the degradation phenomena in carbon/nylon composites as result of moisture absorption. EIS data was collected for composites and neat resins as a function of immersion time in ambient and pressurized (6.2 MPa) 3.5% NaCl solution. EIS was also utilized to understand degradative mechanisms when composites were subject to cathodically induced damage. Concurrent EIS and 3-point mechanical loading was also performed on composites to study the changes in the impedance response as a function of loading. A detailed equivalent circuit analysis is also presented in an attempt to elucidate the degradation phenomena in composites. Gravimetric and 3-point mechanical testing data is also presented to study the effect of ambient and pressurized aqueous environments on composites. Scanning electron micrographs of composites are also included to assist in morphological evaluation.
Show less - Date Issued
- 1993
- PURL
- http://purl.flvc.org/fcla/dt/14907
- Subject Headings
- Impedance spectroscopy, Composite materials, Polymeric composites, Absorption, Environmental degradation--Moisture
- Format
- Document (PDF)
- Title
- Electrochemical impedance spectroscopy of nickel-hydrogen and silver oxide-metal hydride secondary batteries.
- Creator
- Nechev, Kamen S., Florida Atlantic University, Lipka, Stephen M., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
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Full nickel-hydrogen (Ni-H2) boilerplate batteries were cycled and impedance measurements were made at different states-of-charge (SOC), electrolyte concentrations and charge/discharge rates. Experiments were conducted on cells containing new and cycled (11,000 cycles) electrodes. Additionally, an EIS study of Ni-H2 flightweight IPV satellite cells was performed. A number of experiments were conducted on silver oxide-metal hydride batteries. The interest was focused on both negative and...
Show moreFull nickel-hydrogen (Ni-H2) boilerplate batteries were cycled and impedance measurements were made at different states-of-charge (SOC), electrolyte concentrations and charge/discharge rates. Experiments were conducted on cells containing new and cycled (11,000 cycles) electrodes. Additionally, an EIS study of Ni-H2 flightweight IPV satellite cells was performed. A number of experiments were conducted on silver oxide-metal hydride batteries. The interest was focused on both negative and positive electrodes and upon the system itself. This work was preliminary and aided in describing the general performance of the battery. For analysis, the data was fitted to an equivalent electrical circuit using the Nonlinear Least Squares Method (NLSM). The correlation between theoretical and empirical data was sufficiently good.
Show less - Date Issued
- 1993
- PURL
- http://purl.flvc.org/fcla/dt/14958
- Subject Headings
- Nickel-hydrogen batteries, Electrodes, Nickel, Impedance spectroscopy, Electrochemical analysis, Electric batteries--Electrodes
- Format
- Document (PDF)
- Title
- Microfluidic Electrical Impedance Spectroscopy for Blood Analysis.
- Creator
- Rikhtehgaran, Samaneh, Wille, Luc T., Du, E., Florida Atlantic University, Department of Physics, Charles E. Schmidt College of Science
- Abstract/Description
-
The study of the electrical properties of red blood cells (RBCs) plays a crucial role in advancing our understanding of human health. As RBCs age, they undergo changes that affect hemorheology and blood microcirculation, which have far-reaching implications for disease research. Furthermore, the shortage of RBC storage units can be a major issue for patients, underscoring the importance of characterizing RBC aging with respect to cell densities. In individuals with abnormal hemoglobin disease...
Show moreThe study of the electrical properties of red blood cells (RBCs) plays a crucial role in advancing our understanding of human health. As RBCs age, they undergo changes that affect hemorheology and blood microcirculation, which have far-reaching implications for disease research. Furthermore, the shortage of RBC storage units can be a major issue for patients, underscoring the importance of characterizing RBC aging with respect to cell densities. In individuals with abnormal hemoglobin disease, alterations in hemoglobin and its functionality can modify the volume and density of RBCs, making their study even more crucial. To this end, our aim is to investigate the impedance alterations of RBCs after distributing them into different layers based on their densities. We have developed a novel method for non-invasive, rapid, and real-time single-cell analysis of RBCs. Our approach involves the use of electrical impedance spectroscopy (EIS) to study the cells after performing cell fractionation. Our studies indicate an increasing trend for RBC resistance and a decreasing trend for the cell membrane as the density of the layer increases. Additionally, we have developed a method for extracting hemoglobin with high purity from fresh samples of RBCs. By passing lysed RBCs through ultrafiltration devices and removing debris and membranes, we were able to isolate hemoglobin. Using the EIS technique, we studied the alterations of impedance over a frequency range, obtaining valuable insight into the electrical properties of hemoglobin.
Show less - Date Issued
- 2023
- PURL
- http://purl.flvc.org/fau/fd/FA00014223
- Subject Headings
- Blood--Analysis, Erythrocytes--Aging, Hemorheology, Electrical impedance spectroscopy, Microfluidics
- Format
- Document (PDF)
