Dielectrophoresis assisted loading and unloading of microwells for impedance spectroscopy

Mansoorifar, Amin; Koklu, Anil; Sabuncu, Ahmet C.; Beşkök, Ali

doi:10.1002/elps.201700020

Cited by 23 publications

(46 citation statements)

References 51 publications

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“…Amin Mansoorifar et al. successfully captured cells via pDEP, performed dielectric spectroscopy measurements and then unloaded cells utilizing nDEP in an electro‐activated microwell arrays. However, a high alternating current (AC) voltage, exerted to maintain the immobilized single cells in a microchannel, may affect the physiological state of cells.…”

Section: Introductionmentioning

confidence: 99%

“…It comes in two distinct forms: positive dielectrophoresis (pDEP) and negative dielectrophoresis (nDEP) according to the direction of induced forces acting on particles in a non-uniform electric field. Amin Mansoorifar et al [16] successfully captured cells via pDEP, performed dielectric spectroscopy measurements and then unloaded cells utilizing nDEP in an electro-activated microwell arrays. However, a high alternating current (AC) voltage, exerted to maintain the immobilized single cells in a microchannel, may affect the physiological state of cells.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Multiplexing microelectrodes for dielectrophoretic manipulation and electrical impedance measurement of single particles and cells in a microfluidic device

et al. 2019

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This work presents a microfluidic device, which was patterned with (i) microstructures for hydrodynamic capture of single particles and cells, and (ii) multiplexing microelectrodes for selective release via negative dielectrophoretic (nDEP) forces and electrical impedance measurements of immobilized samples. Computational fluid dynamics (CFD) simulations were performed to investigate the fluidic profiles within the microchannels during the hydrodynamic capture of particles and evaluate the performance of single‐cell immobilization. Results showed uniform distributions of velocities and pressure differences across all eight trapping sites. The hydrodynamic net force and the nDEP force acting on a 6 μm sphere were calculated in a 3D model. Polystyrene beads with difference diameters (6, 8, and 10 μm) and budding yeast cells were employed to verify multiple functions of the microfluidic device, including reliable capture and selective nDEP‐release of particles or cells and sensitive electrical impedance measurements of immobilized samples. The size of immobilized beads and the number of captured yeast cells can be discriminated by analyzing impedance signals at 1 MHz. Results also demonstrated that yeast cells can be immobilized at single‐cell resolution by combining the hydrodynamic capture with impedance measurements and nDEP‐release of unwanted samples. Therefore, the microfluidic device integrated with multiplexing microelectrodes potentially offers a versatile, reliable, and precise platform for single‐cell analysis.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Multiplexing microelectrodes for dielectrophoretic manipulation and electrical impedance measurement of single particles and cells in a microfluidic device

et al. 2019

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“…Microfluidics based impedance spectroscopy is a non‐invasive label free technique that offers many advantages over the conventional methods for detection of cells, pathogenic bacteria, toxigenic substances, etc. in food and water matrices . In addition to cell detection, impedance measurements over a wide frequency range can provide information on membrane, cytoplasm, and nucleoplasm dielectric properties .…”

Section: Introductionmentioning

confidence: 99%

Effects of electrode size and surface morphology on electrode polarization in physiological buffers

2018

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Electrode polarization (EP) is inevitable in high conductivity buffers at low AC frequencies due to the accumulation of free charges at the electrode/electrolyte interface. Electrode miniaturization increases EP effect on impedance measurements. In this paper, six gold planar (GP) electrodes having different diameters ( ) were used to investigate the size effect on EP with parallel plate electrode geometry. GP electrode surface was electrochemically deposited with gold nanostructures (GNs) to minimize the EP effect. Equivalent circuit model was used to attain electrode/electrolyte interfacial impedance. Constant phase element model was used to analyze the relation between the size and morphology of electrodes on EP. The surface morphology of gold nanostructured electrodes was examined using SEM, and the influence of different applied potential on the growth of GNs was elucidated with Nernst equilibrium condition. Surface roughness and wettability characteristics were examined performing surface roughness and contact angle measurements, respectively. The improvement of GNs deposited electrode performance was investigated by analytically generated Jurkat cell suspension spectra. The results show that the error in estimating the subcellular properties can be drastically reduced by using GNs deposited electrodes.

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“…The larger the dielectric chamber, the more cells are required to make an accurate measurement. Accurate DS measurements require moderate (∼10%) volume fraction of cells [21]. For example, the number of cells in 1 ml suspension needs to be ∼200 million, assuming 5 µm cell radius.…”

Section: Introductionmentioning

confidence: 99%

Accuracy of the Maxwell–Wagner and the Bruggeman–Hanai mixture models for single cell dielectric spectroscopy

Mansoorifar

Ghosh

Sabuncu

et al. 2017

IET nanobiotechnol.

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Dielectric spectroscopy (DS) is a non-invasive, label-free, and promising technique for measuring dielectric properties of biological cells. Recent developments in microfabrication techniques made it possible to perform DS measurements with minute volume of cell suspensions. However, when the cell size approaches the size of the measurement chamber, especially, for single cell measurements, the analytical models [Maxwell-Wagner and Bruggeman-Hanai (BH) mixture models] to extract cell parameters lose their accuracy. Moreover, variations in the cell position relative to the measurement electrodes decrease the accuracy of the analytical solutions. Impedance spectrum of a typical eukaryotic mammalian cell is generated for different geometrical configurations using finite element. The generated data are fitted to the analytical models and extracted cell parameters are compared with the original values. The results show that BH model works more effectively when chamber to cell radius ratio is <3.5 and chamber height to cell radius ratio is <3. Moreover, it is observed that analytical models estimate cell parameters with major errors when the cells are in the vicinity of the electrodes. However, for high-volume fraction simulations, the BH model was able to predict cell parameters better even in the vicinity of the electrodes.

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Dielectrophoresis assisted loading and unloading of microwells for impedance spectroscopy

Cited by 23 publications

References 51 publications

Multiplexing microelectrodes for dielectrophoretic manipulation and electrical impedance measurement of single particles and cells in a microfluidic device

Multiplexing microelectrodes for dielectrophoretic manipulation and electrical impedance measurement of single particles and cells in a microfluidic device

Effects of electrode size and surface morphology on electrode polarization in physiological buffers

Accuracy of the Maxwell–Wagner and the Bruggeman–Hanai mixture models for single cell dielectric spectroscopy

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