Characterization and optimization of liquid electrodes for lateral dielectrophoresis

Demierre, Nicolas; Braschler, Thomas; Linderholm, Pontus; Seger, Urban; Lintel, Harald van; Renaud, Philippe

doi:10.1039/b612866a

Cited by 136 publications

(130 citation statements)

References 27 publications

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“…8,9 Briefly, liquid electrodes are planar electrodes fabricated on the bottom of dead-end chambers on the side of the main channel. The insulator guides the field lines in the liquid flowing into the main channel and determines the electric field distribution inside the microstructure.…”

Section: Microfluidic Chip Design and The Working Principlementioning

confidence: 99%

“…6,7 Demierre and co-workers have developed a second approach, known as "liquid electrodes". 8,9 This novel device is based on the use of planar electrodes fabricated on the bottom of dead-end chambers placed on the side of the main flowing channel. The application of coplanar microelectrodes simplifies the fabrication process and reduces the costs.…”

Section: Introductionmentioning

confidence: 99%

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An impedance-based flow microcytometer for single cell morphology discrimination

et al. 2014

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Cell shape is a fundamental biological feature, providing specific information about physiological or pathological cellular conditions. Most of the state-of-the-art microfluidic cytometers, however, only allow simple cell analysis, including viability studies, cell counting and sorting. In this work, we present a non-invasive, label-free device capable of single cell morphology discrimination in continuous flow. The device is based on the principle of liquid electrodes, fabricated in a cross configuration around a sensing zone. This arrangement allows measurement of cell impedance along orthogonal orientations and extraction of an index describing cell shape anisotropy. By adding prior to the sensing volume a series of lateral liquid electrodes, the particle stream was focused toward the channel midline and each cell was oriented in a specific direction before shape sensing. We demonstrate the proof of concept by performing spherical and elongated particle discrimination. As an application, we show that the shape changes experienced during cell division can be monitored and characterized. In particular, budding yeasts at different stages of the mitotic cycle were identified by extracting their anisotropy index.

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Section: Microfluidic Chip Design and The Working Principlementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

An impedance-based flow microcytometer for single cell morphology discrimination

et al. 2014

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“…On top of the electrodes the channels were formed in polymer (SU-8 2075 MicroChem, Berlin, Germany) by photolithography [13,14]. The chips were sealed by bonding a Pyrex lid with holes for the fluidic connections to the chips as described in [15] by applying pressure and heat.…”

Section: Chip Fabrication and Measurement Setupmentioning

confidence: 99%

Coplanar Electrode Layout Optimized for Increased Sensitivity for Electrical Impedance Spectroscopy

Clausen

Skands²,

Bertelsen

et al. 2014

Micromachines

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Abstract:This work describes an improvement in the layout of coplanar electrodes for electrical impedance spectroscopy. We have developed, fabricated, and tested an improved electrode layout, which improves the sensitivity of an impedance flow cytometry chip. The improved chip was experimentally tested and compared to a chip with a conventional electrode layout. The improved chip was able to discriminate 0.5 μm beads from 1 μm as opposed to the conventional chip. Furthermore, finite element modeling was used to simulate the improvements in electrical field density and uniformity between the electrodes of the new electrode layout. Good agreement was observed between the model and the obtained experimental results.

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“…This DC impedance cytometer using polyelectrolyte gel electrodes has also been integrated with light emitting diodes (LEDs) and solidstate photomultipliers to build a portable system for simultaneous fluorescence and impedance detection (74). Demierre et al also used a setup in which large electrodes are placed distant from the microfluidic channel to create non-uniform electric fields for dielectrophoretic particle manipulation (75). By avoiding electrode polarization using these electrolytebased electrodes, impedance flow cytometry may be applied at very low frequencies to examine ligand binding or other cell membrane events.…”

Section: Microfluidic Coulter Systems Sensitivitymentioning

confidence: 99%

Microfluidic impedance‐based flow cytometry

Berardino²,

et al. 2010

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Microfabricated flow cytometers can detect, count, and analyze cells or particles using microfluidics and electronics to give impedance-based characterization. Such systems are being developed to provide simple, low-cost, label-free, and portable solutions for cell analysis. Recent work using microfabricated systems has demonstrated the capability to analyze micro-organisms, erythrocytes, leukocytes, and animal and human cell lines. Multifrequency impedance measurements can give multiparametric, high-content data that can be used to distinguish cell types. New combinations of microfluidic sample handling design and microscale flow phenomena have been used to focus and position cells within the channel for improved sensitivity. Robust designs will enable focusing at high flowrates while reducing requirements for control over multiple sample and sheath flows. Although microfluidic impedance-based flow cytometers have not yet or may never reach the extremely high throughput of conventional flow cytometers, the advantages of portability, simplicity, and ability to analyze single cells in small populations are, nevertheless, where chip-based cytometry can make a large impact. ' 2010International Society for Advancement of Cytometry Key terms microfluidics; impedance characterization; label free; single cell analysis; hydrodynamic focusing; sorting MICROFLUIDIC flow cytometers can bring many advantages to the field of flow cytometry (FCM). Compared to typical flow cytometry channel sizes, the miniaturized dimensions permit microfluidic systems to analyze single cells, to identify cellular variability in gene expression, or drug response within a cell population. Chipbased cytometers can have lower size and costs than conventional benchtop instruments, and may be portable. Today, the developmental aim for microfluidic systems is to reach the same sensitivity and capability for multiparametric analyses as delivered by conventional flow cytometers. Many efforts have been made to improve existing devices and to create new miniaturized high-end instruments. Microfluidic chips can incorporate on-chip cell preparation, cell culture, lysis, and modules for optical, electrophoretic, or genomic analysis (1). They are also suitable for analysis of cells in suspension as well as adherent cells.Miniaturized cytometry devices will have high impact in the development of point-of-care devices in developing countries. Accurate CD4 1 T-cell counts are used to monitor human immunodeficiency virus (HIV)-infected patients, and various thresholds of the number of CD4 1 T lymphocytes per ll of whole blood are used to start antiretroviral therapy (2-5). A simple, single-purpose CD4 cell counting device, which does not require standard laboratory equipment or trained laboratory personnel, could help some of the 33 million HIV-infected people worldwide monitor the stage of infection (6)(7)(8). In this application, increased analysis throughput is a secondary concern compared to increased sensitivity and specificity. Portable, miniatu...

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Characterization and optimization of liquid electrodes for lateral dielectrophoresis

Cited by 136 publications

References 27 publications

An impedance-based flow microcytometer for single cell morphology discrimination

An impedance-based flow microcytometer for single cell morphology discrimination

Coplanar Electrode Layout Optimized for Increased Sensitivity for Electrical Impedance Spectroscopy

Microfluidic impedance‐based flow cytometry

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