Elham Salimi

Elham Salimi
University of Manitoba | UMN · Department of Electrical and Computer Engineering

PhD

About

42
Publications
5,859
Reads
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374
Citations
Education
May 2011 - November 2016
University of Manitoba
Field of study
  • Electrical Engineering
May 2008 - February 2011
University of Manitoba
Field of study
  • Electrical Engineering
September 2003 - September 2007
Amirkabir University of Technology
Field of study
  • Electrical Engineering

Publications

Publications (42)
Article
The dielectric properties of biological cells can be used to gain information on their physiology and morphology. This paper reports the first measurements of the dielectric spectra of viable and non-viable cells over the full beta-dispersion (interfacial) frequency range. Dielectrophoresis (DEP) single cell in-flow techniques were employed to quan...
Article
In this work, we present an optical transit dielectrophoresis (DEP) flow cytometer for parallel single‐cell analysis. Each cell's dielectric property is inferred from velocity perturbations due to DEP actuation in a microfluidic channel. Dual LED sources facilitate velocity measurement by producing two transit shadows for each cell passing through...
Article
Trypan blue dye exclusion first was proposed as a means of measuring mammalian cell damages over a century ago in 1917. Despite extensive documentation of its limitations, it remains the “gold standard” method of measuring cell viability in common use today. But can this method truly measure viability? And how do we define cell viability, for that...
Article
The ability to monitor the status of cells during nutrient limitation is important for optimizing bioprocess growth conditions in batch and fed‐batch cultures. The activity level of Na+/K+ ATPase pumps and cytoplasm ionic concentrations are directly influenced by the nutrient level, and thus, cytoplasm conductivity can be used as a marker‐less indi...
Article
The dielectric properties of cells are directly related to their morphological and physiological properties and can be used to monitor their status when exposed to stress conditions. In this work, dual-frequency dielectrophoresis (DEP) cytometry was employed to measure changes in the membrane capacitance and cytoplasm conductivity of single Chinese...
Chapter
Dielectric measurement techniques such as impedance spectroscopy and dielectrophoresis methods have been employed to study biological phenomena based on the intrinsic electrical properties of cells and their sub-compartments (membrane capacitance and conductance, cytosol conductivity, etc.). They are label-free and non-invasive and have shown promi...
Article
Full-text available
Abstract In mammalian cells cytoplasm ion concentrations and hence cytoplasm conductivity is an important indicator of their physiological state. Changes in the cytoplasm conductivity has been associated with physiological changes such as progression of cancer and apoptosis. In this work, a model that predicts the effects of physiological changes i...
Article
Dielectrophoresis (DEP) cytometry was used to investigate changes in the membrane capacitance, membrane conductance, and cytoplasm conductivity of single Chinese hamster ovary (CHO) cells subjected to thermal stress. CHO cells were exposed to temperatures ranging from 37 °C to 50 °C for 15 min and measured immediately after exposure. Heat-treated c...
Article
Nutrient depletion in fed-batch cultures and at the end of batch cultures is among the main causes of stress on cells and a trigger of apoptosis. In this study, we investigated changes in the cytoplasm conductivity of Chinese hamster ovary (CHO) cells under controlled starvation. Employing a single-cell dielectrophoresis (DEP) cytometer, we measure...
Article
Full-text available
Applying sufficiently strong pulsed electric fields to a cell can permeabilize the membrane and subsequently affect its dielectric properties. In this study, we employ a microfluidicdielectrophoresis cytometry technique to simultaneously electroporate and measure the time-dependent dielectric response of single Chinese hamster ovary cells. Using ex...
Article
Full-text available
We present a dielectric model and its parameters for Chinese hamster ovary (CHO) cells based on a double-shell structure which includes the cell membrane, cytoplasm, nuclear envelope, and nucleoplasm. Employing a dielectrophoresis(DEP) based technique and a microfluidic system, the DEP response of many single CHO cells is measured and the spectrum...
Conference Paper
We present a microfluidic device for measuring the dielectrophoresis (DEP) response of single Chinese hamster ovary cells while in flow. The device measures the sign and amplitude of the DEP induced translation of single cells at two frequencies by sensing the change in impedance at microwave frequency as the cell passes over a multi-electrode tran...
Article
A universal, torque-mixing method for magnetic resonance spectroscopy is presented. In analogy to resonance detection by magnetic induction, the transverse component of a precessing dipole moment can be measured in sensitive broadband spectroscopy, here using a resonant mechanical torque sensor. Unlike induction, the torque amplitude allows equilib...
Conference Paper
Studying biological phenomena at the cellular level allows understanding the basics of cellular function and the mechanism of their interactions with internal or external stimuli. Among available single cell analysis techniques such as, fluorescent labeling, magnetic labeling, mechanical, and electrical approaches, electrical ones are of special in...
Conference Paper
Full-text available
We present a multi-frequency dielectrophoresis (DEP) based microfluidic device for characterizing the complex dielectric properties of single micron-sized particles while in flow. The device employs a multi-electrode transmission line sensor coupled to a microwave-interferometer, capable of subattofarad sensitivity, for detecting the DEP-induced tr...
Article
A microwave frequency reflectometer with atto-farad capacitance sensitivity has been designed and tested for detection of particles and cells in a microfluidic channel. The design is implemented on a printed circuit board. Capacitance sensitivity up to 1.25 aF is achieved in a 50 Hz bandwidth. The sensor was used for detection of 5.7 μm polystyrene...
Article
One of the main uses of adenosine triphosphate (ATP) within mammalian cells is powering the Na +/K+ ATPase pumps used to maintain ion concentrations within the cell. Since ion concentrations determine the cytoplasm conductivity, ATP concentration is expected to play a key role in controlling the cytoplasm conductivity. The two major ATP production...
Conference Paper
In this work the dielectric response evaluated by dielectrophoresis (DEP) cytometer was used to track cytoplasm conductivity and therefore ion concentrations during apoptosis induced by inhibition of mitochondrial ATP production. Oligomycin was used to inhibit mitochondrial ATP production in Chinese hamster ovary (CHO) cells. During induction healt...
Conference Paper
Electroporation affects the dielectric properties of cells by creating pores in their membrane which allow transport of ions. Dielectrophoresis (DEP) is a powerful technique to investigate electroporation of single biological cells. Here we study the frequency dependent response of Chinese hamster ovary (CHO) cells and investigate the effect of dif...
Article
To ensure maximum productivity of recombinant proteins it is desirable to prolong cell viability during a mammalian cell bioprocess, and therefore important to carefully monitor cell density and viability. In this study, five different and independent methods of monitoring were applied to Chinese hamster ovary (CHO) cells grown in a batch culture i...
Article
Full-text available
In nanosecond pulsed electroporation of biological cells nanosecond duration pulses with high frequency spectral content are applied to the cell. We show that accurate modeling of the electroporation process on these time scales requires considering the effect of the dielectric dispersion on the electric potential across the membrane. We describe t...
Conference Paper
We present a semi-automated event identification method for collecting the dielectrophoretic signatures of cells flowing through a dieletrophoretic cytometer. The marker free dielectrophoresis (DEP) cytometer presented in this study is capable of detecting electronic signatures of cells which identifies Claussius-Mossotti factor (CMF). The CMF can...
Conference Paper
We describe a microfluidic device integrated with a microwave interferometric sensor that is able to simultaneously electroporate and measure the dielectrophoresis (DEP) response of single biological cells. The system can measure changes in dielectric properties of a cell permeabilized using a high-intensity pulsed electric field (PEF) from a few s...
Conference Paper
We present a microfluidic device able to electroporate and measure the resultant changes in dielectric properties of single biological cells. The device can measure the dielectrophoresis (DEP) response of the electroporated cell from a few seconds after exposure to electroporating pulses. Studying electroporation at the single cell level can provid...
Conference Paper
We present a semi-automated event identification method for collecting the dielectrophoretic signatures of cells flowing through a dieletrophoretic cytometer. The marker free dielectrophoresis (DEP) cytometer presented in this study is capable of detecting electronic signatures of cells which identifies Claussius-Mossotti factor (CMF). The CMF can...
Article
Full-text available
The instrument described here is an all-electronic dielectrophoresis (DEP) cytometer sensitive to changes in polarizability of single cells. The important novel feature of this work is the differential electrode array that allows independent detection and actuation of single cells within a short section ( ∼ 300 μm) of the microfluidic channel. DEP...
Article
Electroporation affects the dielectric properties of cells by creating pores in their membrane which allow transport of ions in and out of cells. Dielectric characterization techniques are powerful tools to investigate the time evolution of electroporation induced changes. Here we employ a dielectrophoresis (DEP) technique to study the effect of el...
Article
Full-text available
Dielectric particles flowing through a microfluidic channel over a set of coplanar electrodes can be simultaneously capacitively detected and dielectrophoretically (DEP) actuated when the high (1.45 GHz) and low (100 kHz-20 MHz) frequency electromagnetic fields are concurrently applied through the same set of electrodes. Assuming a simple model in...
Article
We designed and developed a sensor that allows us to electronically monitor changes in physiological properties of biological cells. Based on the ability to simultaneously detect and dielectrophoretically (DEP) actuate cells, we can observe unique changes in the electronic detection signature that are directly related to polarizability of the cell....
Conference Paper
Full-text available
In order to model nanosecond pulse electroporation of the cell membrane the effect of dielectric relaxation of membrane molecules has to be considered. Since the formation of pores is a nonlinear process the dielectric relaxation effects have to be incorporated as dispersion in the time-domain. This paper presents the time-domain implementation of...

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