| 1. |
- Beech, Jason P., et al.
(författare)
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Electrokinetic wall effect mechanisms and applications
- 2020
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Ingår i: MicroTAS 2020 - 24th International Conference on Miniaturized Systems for Chemistry and Life Sciences. - 9781733419017 ; , s. 42-43
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Konferensbidrag (refereegranskat)abstract
- Under the application of longitudinal electric fields in microchannels, microparticles experience lift forces that push them away from the channel walls and affect their trajectories. At high frequencies (>100KHz) the dielectrophoretic forces dominate and are well understood but at lower frequencies there is little agreement as to the exact nature of the forces, how they are generated and how they vary due to the many different experimental conditions that are used in microfluidics devices. Here we present an experimental study of these mechanisms.
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| 2. |
- Ho, Bao D., et al.
(författare)
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Cell sorting using electrokinetic deterministic lateral displacement
- 2020
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Ingår i: Micromachines. - : MDPI AG. - 2072-666X. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- We show that by combining deterministic lateral displacement (DLD) with electrokinetics, it is possible to sort cells based on differences in their membrane and/or internal structures. Using heat to deactivate cells, which change their viability and structure, we then demonstrate sorting of a mixture of viable and non-viable cells for two different cell types. For Escherichia coli, the size change due to deactivation is insufficient to allow size-based DLD separation. Our method instead leverages the considerable change in zeta potential to achieve separation at low frequency. Conversely, for Saccharomyces cerevisiae (Baker’s yeast) the heat treatment does not result in any significant change of zeta potential. Instead, we perform the sorting at higher frequency and utilize what we believe is a change in dielectrophoretic mobility for the separation. We expect our work to form a basis for the development of simple, low-cost, continuous label-free methods that can separate cells and bioparticles based on their intrinsic properties.
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| 3. |
- Ho, Bao D., et al.
(författare)
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Charge-based separation of micro-and nanoparticles
- 2020
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Ingår i: Micromachines. - : MDPI AG. - 2072-666X. ; 11:11
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Tidskriftsartikel (refereegranskat)abstract
- Deterministic Lateral Displacement (DLD) is a label-free particle sorting method that separates by size continuously and with high resolution. By combining DLD with electric fields (eDLD), we show separation of a variety of nano and micro-sized particles primarily by their zeta potential. Zeta potential is an indicator of electrokinetic charge—the charge corresponding to the electric field at the shear plane—an important property of micro-and nanoparticles in colloidal or separation science. We also demonstrate proof of principle of separation of nanoscale liposomes of different lipid compositions, with strong relevance for biomedicine. We perform careful characterization of relevant experimental conditions necessary to obtain adequate sorting of different particle types. By choosing a combination of frequency and amplitude, sorting can be made sensitive to the particle subgroup of interest. The enhanced displacement effect due to electrokinetics is found to be significant at low frequency and for particles with high zeta potential. The effect appears to scale with the square of the voltage, suggesting that it is associated with either non-linear electrokinetics or dielectrophoresis (DEP). However, since we observe large changes in separation behavior over the frequency range at which DEP forces are expected to remain constant, DEP can be ruled out.
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| 4. |
- Ho, Bao D., et al.
(författare)
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High throughput extracellular vesicle sorting using electrokinetic deterministic lateral displacement
- 2020
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Ingår i: MicroTAS 2020 - 24th International Conference on Miniaturized Systems for Chemistry and Life Sciences. - 9781733419017 ; , s. 637-638
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Konferensbidrag (refereegranskat)abstract
- We present a microfluidic device that can sort nanosized extracellular vesicles (EVs) based on electrokinetics and Deterministic Lateral Displacement (DLD). The device is made from PDMS using standard soft-lithography, can separate particles down to 200 nm, and what is more, can achieve almost two orders of magnitude higher throughput than an otherwise single electrokinetic DLD device.
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| 5. |
- Hochstetter, Axel, et al.
(författare)
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Deterministic Lateral Displacement : Challenges and Perspectives
- 2020
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 14:9, s. 10784-10795
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Forskningsöversikt (refereegranskat)abstract
- The advent of microfluidics in the 1990s promised a revolution in multiple industries from healthcare to chemical processing. Deterministic lateral displacement (DLD) is a continuous-flow microfluidic particle separation method discovered in 2004 that has been applied successfully and widely to the separation of blood cells, yeast, spores, bacteria, viruses, DNA, droplets, and more. Deterministic lateral displacement is conceptually simple and can deliver consistent performance over a wide range of flow rates and particle concentrations. Despite wide use and in-depth study, DLD has not yet been fully elucidated or optimized, with different approaches to the same problem yielding varying results. We endeavor here to provide up-to-date expert opinion on the state-of-art and current fundamental, practical, and commercial challenges with DLD as well as describe experimental and modeling opportunities. Because these challenges and opportunities arise from constraints on hydrodynamics, fabrication, and operation at the micro- and nanoscale, we expect this Perspective to serve as a guide for the broader micro- and nanofluidic community to identify and to address open questions in the field.
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| 6. |
- Porro, Gloria, et al.
(författare)
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Deterministic lateral displacement systems with arrayed three-dimensional electrodes for tunable particle sorting
- 2020
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Ingår i: MicroTAS 2020 - 24th International Conference on Miniaturized Systems for Chemistry and Life Sciences. - 9781733419017 ; , s. 655-656
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Konferensbidrag (refereegranskat)abstract
- Deterministic Lateral Displacement (DLD) is a passive technique employed for particles sorting. We recently introduced a DLD device composed of arrayed three-dimensional metal-covered pillars that can be used to locally apply an electric field. With our system we can exploit the dielectrophoretic (DEP) effect to exert forces on the bioparticles to be sorted, thus dynamically tuning the critical size of the passive sorting device.
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| 7. |
- Ström, Oskar E., et al.
(författare)
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DNA concentration wave formation in pillar arrays
- 2020
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Ingår i: MicroTAS 2020 - 24th International Conference on Miniaturized Systems for Chemistry and Life Sciences. - 9781733419017 ; , s. 240-241
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Konferensbidrag (refereegranskat)abstract
- High throughput in particle and molecular sorting schemes is an important performance indicator and can be realized through increased volumetric processing rates or increased concentrations. Here we investigate the effect of increased concentration of high-molecular weight DNA in micropillar arrays for deterministic lateral displacement (DLD). We find that the array imposes regular fluctuations in the concentration of the DNA if the sample concentration and flow rates exceed respective threshold values. We characterize the resulting concentration waves and study their influence on microsphere trajectories in the device. We expect our results to be relevant e.g. for sample preparation of cell lysates which can often be complicated by the release of chromosomal DNA.
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