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This paper presents a microfahricated impedance spectroscopy flow cytometer which permits rapid and easy dielectric characterization of cells as they flow in a microchannel. Both a simple theoretical model and a finite element simulation... more
This paper presents a microfahricated impedance spectroscopy flow cytometer which permits rapid and easy dielectric characterization of cells as they flow in a microchannel. Both a simple theoretical model and a finite element simulation show that the effects of particle size ...
Research Interests: Finite Element Methods, Microfluidics, Dielectrophoresis, Impedance Spectroscopy, Finite Element Analysis, and 14 moreElectrochemical Impedance Spectroscopy, Calibration, Dielectric Spectroscopy, System, Micro Electro Mechanical System, Frequency, Dielectric Properties, Conductivity, Finite element simulation, Spectrum, Electrophoresis, Particle Size, Electrodes, and Theoretical Model
Dielectric spectroscopy is a powerful tool for investigating the dielectric properties of biological particles in suspension. For low volume fractions, the dielectric properties of the particles are related to the measured properties of... more
Dielectric spectroscopy is a powerful tool for investigating the dielectric properties of biological particles in suspension. For low volume fractions, the dielectric properties of the particles are related to the measured properties of the suspension by Maxwell's mixture equation. A number of different techniques can be used to measure the dielectric spectrum in the frequency domain or the time domain. In time domain dielectric spectroscopy, data can be converted into the frequency domain using convolution or Fourier transform, prior to data analysis. In this paper, we present a general method for transforming Maxwell's mixture equation from the frequency domain to the time domain allowing analysis of cell dielectric properties directly in the time domain. The derivation is based on the Laplace transform of the single shell model for a spherical particle, and can be extended to the multi-shell model. For a single shelled cell two characteristic relaxation time constants are derived. The results are compared with published analytical models. We show that the original frequency dependent mixture equation can be recovered by Fourier transform back to the frequency domain. As a result, a general relationship for the dielectric response of a mixture of particles is presented which links the frequency and time domains.
Research Interests: Engineering, Data Analysis, Dielectric Spectroscopy, Physical sciences, Laplace Transform, and 13 moreDielectric Properties, Single Cell, Spectrum, Laplace transformation, Frequency Dependence, Fourier transform, Analytical Model, Time Domain, Shell Model, Time Domain Analysis, Fourier Transformation, Frequency Domain, and Volume Fraction
Sun, T., Gawad, S., Green, NG and Morgan, H. (2006) Analytical and Numerical Modeling for Impedance Spectrum Analysis of Single cell in high throughput Microfluidic Cytometers. In: The Medicine, Health and Life Sciences (MHLS) PG... more
Sun, T., Gawad, S., Green, NG and Morgan, H. (2006) Analytical and Numerical Modeling for Impedance Spectrum Analysis of Single cell in high throughput Microfluidic Cytometers. In: The Medicine, Health and Life Sciences (MHLS) PG conference, 6 - 7 June 2006, University of ...
Sun, T., Gawad, S., Green, NG and Morgan, H. (2006) Broadband Impedance Spectroscopy for Single Particles in High Throughput Microfluidic Cytometer using Pseudorandom Noise. In: International Conference on Bio-Nano-Informatics Fusion... more
Sun, T., Gawad, S., Green, NG and Morgan, H. (2006) Broadband Impedance Spectroscopy for Single Particles in High Throughput Microfluidic Cytometer using Pseudorandom Noise. In: International Conference on Bio-Nano-Informatics Fusion & International Forum on ...
Sun, T., Gawad, S., Green, NG and Morgan, H. (2006) Impedance Spectroscopy: Single Cell Cytometry using Maximum Length Sequences Analysis. In: The 10th Annual European Conference On Micro & Nanoscale Technologies for the Biosciences,... more
Sun, T., Gawad, S., Green, NG and Morgan, H. (2006) Impedance Spectroscopy: Single Cell Cytometry using Maximum Length Sequences Analysis. In: The 10th Annual European Conference On Micro & Nanoscale Technologies for the Biosciences, November 14-16, 2006, ...
A maximum length sequence (MLS) is used to perform broadband impedance spectroscopy on a dielectric sample. The method has a number of advantages over other pulse-based or frequency sweep techniques. It requires the application of a very... more
A maximum length sequence (MLS) is used to perform broadband impedance spectroscopy on a dielectric sample. The method has a number of advantages over other pulse-based or frequency sweep techniques. It requires the application of a very short sequence of voltage steps in the microsecond range and therefore allows the measurement of time-dependent impedance of a sample with high temporal resolution over a large bandwidth. The technique is demonstrated using a time-invariant passive RC network. The impedance of single biological cell flowing in a microfluidic channel is also measured, showing that MLS is an ideal method for high speed impedance analysis.
Research Interests: Engineering, Biomedical Engineering, Flow Cytometry, Temporal Resolution, Impedance Spectroscopy, and 12 moreScientific Instruments, Humans, Physical sciences, CHEMICAL SCIENCES, Spectrum analysis, Reproducibility of Results, Sensitivity and Specificity, Erythrocytes, Equipment Design, Equipment Failure Analysis, Electric Impedance, and (Maximum Length Sequence
A novel broadband high-speed impedance spectrometer has been developed for the analysis of single biological particles in a high-throughput microfluidic cytometer. The technique is based on obtaining the impulse response of the system... more
A novel broadband high-speed impedance spectrometer has been developed for the analysis of single biological particles in a high-throughput microfluidic cytometer. The technique is based on obtaining the impulse response of the system using maximum length sequences (MLS) as the excitation signal. The impulse response is converted into the frequency domain using Fast Fourier Transform (FFT). Theoretical modeling and simulation of a single cell suspended in the cytometer show that the MLS technique is capable of high precision single particle analysis.
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Over the last century a number of techniques have been developed which allow the measurement of the dielectric properties of biological particles in fluid suspension. The majority of these techniques are limited by the fact that they only... more
Over the last century a number of techniques have been developed which allow the measurement of the dielectric properties of biological particles in fluid suspension. The majority of these techniques are limited by the fact that they only provide an average value for the dielectric properties of a collection of particles. More recently, with the advent of microfabrication techniques and the Lab-on-a-chip, it has been possible to perform dielectric spectroscopic experiments on single biological particles suspended in physiological media. In this paper we review current methods for single cell dielectric spectroscopy. We also discuss alternative single cell dielectric measurement techniques, specifically the ac electrokinetic methods of dielectrophoresis and electrorotation. Single cell electrical impedance spectroscopy is also discussed with relevance to a microfabricated flow cytometer. We compare impedance spectroscopy data obtained from measurements made using a microfabricated flow cytometer with simulation data obtained using an equivalent circuit model for the device.
Research Interests: Engineering, Microfluidics, Modeling, Lab On A Chip, Dielectrophoresis, and 10 moreImpedance Spectroscopy, Instrumentation, Dielectric Spectroscopy, Physical sciences, Electrical Impedance Spectroscopy, Dielectric Properties, Equivalent Circuit, Single Cell, System on a Chip, and Electrical Impedance
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Abstract A number of micro fabricated flow cytometry devices have been proposed based on electrical' 2 or optical3 detection techniques. On chip marker-free differentiation of cells using... more
Abstract A number of micro fabricated flow cytometry devices have been proposed based on electrical' 2 or optical3 detection techniques. On chip marker-free differentiation of cells using impedance spectroscopy was demonstrated between leukocyte sub-populations ...
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Gawad, Shady, Sun, Tao, Holmes, David, Green, Nicolas G and Morgan, Hywel (2005) Maximum Length Sequences for Dielectric Spectroscopy: Application to a Microflow Cytometer. At The 9th Annual European Conference on Micro &... more
Gawad, Shady, Sun, Tao, Holmes, David, Green, Nicolas G and Morgan, Hywel (2005) Maximum Length Sequences for Dielectric Spectroscopy: Application to a Microflow Cytometer. At The 9th Annual European Conference on Micro & Nanoscale Technologies for the Biosciences, Montreux, Switzerland, 15 - 17 Nov 2005. ... Full text not available from this repository. ... RDF+N-Triples, RDF+N3, RDF+XML, Browse.
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Morgan, Hywel, Benazzi, Giuseppe, Sun, Tao, Green, Nicolas G, Holmes, David and Gawad, Shady (2006) Single Cell Impedance Spectroscopy. At Bio-Dielectrics: Theories, Mechanisms and Applications, Annual Conference 2006 of the Dielectrics... more
Morgan, Hywel, Benazzi, Giuseppe, Sun, Tao, Green, Nicolas G, Holmes, David and Gawad, Shady (2006) Single Cell Impedance Spectroscopy. At Bio-Dielectrics: Theories, Mechanisms and Applications, Annual Conference 2006 of the Dielectrics Group of the Institute of Physics, University of Leicester, Leicester, UK, 10 - 12 Apr 2006. ... Full text not available from this repository. ... RDF+N-Triples, RDF+N3, RDF+XML, Browse.
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ABSTRACT
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A novel microfabricated flow cytometer for simultaneous impedance and optical measurement of single cells and particles is described in this chapter. We discuss the sensitivity of the system with regard to the impedance sensor and... more
A novel microfabricated flow cytometer for simultaneous impedance and optical measurement of single cells and particles is described in this chapter. We discuss the sensitivity of the system with regard to the impedance sensor and describe the optical setup. The relevant parameters related to the experimental setup and sample preparation are discussed. The use of dielectrophoretic forces for particle manipulation is presented as a simple enabling technology, which allows the manipulation of particles within microfluidic devices. The fabrication processes required to produce the impedance sensor chips are described with relevance to the chip design and features. Finally, the system is used to discriminate between different marine algae populations.