Impedance Matching in Dielectrophoresis Experiments

Boldt, Niklas P.; Malti, Danai Eleni; Damm, Sebastian; Barai, Arohi; Birkholz, M.; Thewes, R.

doi:10.1109/biocas49922.2021.9645025

Cited by 6 publications

(5 citation statements)

References 7 publications

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“…At low frequencies, the electronic double layer dominates the impedance of the setup, but with increasing frequency, the double layer, which acts as a capacitor, becomes less dominant. At higher frequencies, the voltage drop across the medium dominates the overall impedance of the device [55]. This measurement helps selecting the correct amplifier for the experiment.…”

Section: Methodsmentioning

confidence: 99%

High‐throughput dielectrophoretic separator based on printed circuit boards

et al. 2022

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The separation of particles with respect to their intrinsic properties is an ongoing task in various fields such as biotechnology and recycling of electronic waste.Especially for small particles in the lower micrometer or nanometer range, separation techniques are a field of current research since many existing approaches lack either throughput or selectivity. Dielectrophoresis (DEP) is a technique that can address multiple particle properties, making it a potential candidate to solve challenging separation tasks. Currently, DEP is mostly used in microfluidic separators and thus limited in throughput. Additionally, DEP setups often require expensive components, such as electrode arrays fabricated in the clean room.Here, we present and characterize a separator based on two inexpensive customdesigned printed circuit boards (80 × 120 mm board size). The boards consist of interdigitated electrode arrays with 250 μm electrode width and spacing. We demonstrate the separation capabilities using polystyrene particles ranging from 500 nm to 6 μm in monodisperse experiments. Further, we demonstrate selective trapping at flow rates up to 240 ml∕h in the presented device for a binary mixture. Our experiments demonstrate an affordable way to increase throughput in electrode-based DEP separators.

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Section: Methodsmentioning

confidence: 99%

High‐throughput dielectrophoretic separator based on printed circuit boards

et al. 2022

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“…Ad hoc assumptions had thus to be made. Before running experiments with biological cells, the commercially acquired microfluidic flow cell was tested with suspensions of polystyrene microparticles in order to check for its ability to deliver reproducible results ( Boldt et al, 2021 ); this latter source also presents further details of the microfluidic flow cell.…”

Section: Methodsmentioning

confidence: 99%

“…The magnified view shows the cells’ behaviour due to the DEP field, in which high lipid cells (blue colour) are being repelled at the electrodes edge while low lipid cells (red colour) are passing through the top-bottom electrode structure. For further details see ( Boldt et al, 2021 ).…”

Section: Methodsmentioning

confidence: 99%

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Separation of Heterotrophic Microalgae Crypthecodinium cohnii by Dielectrophoresis

Birkholz

Malti

Hartmann

et al. 2022

Front. Bioeng. Biotechnol.

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Microalgae constitute an abundant source of poly-unsaturated fatty acids which are applied in various biotechnological fields such as pharmaceuticals and food supplement. Separating microalgae cells with respect to their lipid content would establish a relevant at-line analytical technique. The present study demonstrates an electrical approach for the separation of the lipid-producing microalgae Crypthecodinium cohnii using the effect of dielectrophoresis (DEP) in a microfluidic flow cell. Microalgae were cultivated for 8 days, while cell growth was characterized by optical density, dry cell weight, glucose concentration and lipid content via fluorescence microscopy. The size distribution of cells during cultivation was thoroughly investigated, since the DEP force scales with cell volume, but also depends on lipid content via cell electrophysiological constants. Thus, the challenge was to deconvolute one separation effect from the other, while the electrical cell constants of C. cohnii are not known yet. The DEP-dependent separation was realized by slanted top-bottom electrodes with the flowing cell suspension between them. Turning on the voltage deflected the cells from their initial path as determined by the streaming and thus changed their direction of flow. The separation efficiency of DEP was tested for various electrical field strengths and its performance was determined by quantitative analysis of optical and fluorescence videos. It could be shown for all size groups that the most lipid-containing cells were always subject to DEP separation and that the method is thus not only suitable for process analysis, but also for strain selection of the most productive cell lines.

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“…While the ∇E 2 can be directly derived by FEM simulation to obtain a rough picture, it will still deviate from real values, as fabrication tolerances on the electrode structures are generally not included. Furthermore, the importance of correct impedance matching and the voltage drop inside DEP actuators should be taken into account when predicting the DEP effect of the device [ 137 , 138 ].…”

Section: Perspectives and Challengesmentioning

confidence: 99%

Dielectrophoresis: An Approach to Increase Sensitivity, Reduce Response Time and to Suppress Nonspecific Binding in Biosensors?

2022

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The performance of receptor-based biosensors is often limited by either diffusion of the analyte causing unreasonable long assay times or a lack of specificity limiting the sensitivity due to the noise of nonspecific binding. Alternating current (AC) electrokinetics and its effect on biosensing is an increasing field of research dedicated to address this issue and can improve mass transfer of the analyte by electrothermal effects, electroosmosis, or dielectrophoresis (DEP). Accordingly, several works have shown improved sensitivity and lowered assay times by order of magnitude thanks to the improved mass transfer with these techniques. To realize high sensitivity in real samples with realistic sample matrix avoiding nonspecific binding is critical and the improved mass transfer should ideally be specific to the target analyte. In this paper we cover recent approaches to combine biosensors with DEP, which is the AC kinetic approach with the highest selectivity. We conclude that while associated with many challenges, for several applications the approach could be beneficial, especially if more work is dedicated to minimizing nonspecific bindings, for which DEP offers interesting perspectives.

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Impedance Matching in Dielectrophoresis Experiments

Cited by 6 publications

References 7 publications

High‐throughput dielectrophoretic separator based on printed circuit boards

High‐throughput dielectrophoretic separator based on printed circuit boards

Separation of Heterotrophic Microalgae Crypthecodinium cohnii by Dielectrophoresis

Dielectrophoresis: An Approach to Increase Sensitivity, Reduce Response Time and to Suppress Nonspecific Binding in Biosensors?

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