| 31. |
- Ho, Bao D., et al.
(författare)
-
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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| 32. |
- Ho, Bao D., et al.
(författare)
-
Charge-based separation of micro-and nanoparticles
- 2020
-
Ingår i: Micromachines. - : MDPI AG. - 2072-666X. ; 11:11
-
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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| 33. |
- Ho, Bao D., et al.
(författare)
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Combining electrokinetics with deterministic lateral displacement
- 2016
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Ingår i: 20th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2016. - 9780979806490 ; , s. 1559-1560
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Konferensbidrag (refereegranskat)abstract
- We make Deterministic Lateral Displacement (DLD) flexible by combining it with AC electrokinetics.
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| 34. |
- Ho, Bao D., et al.
(författare)
-
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
-
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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| 35. |
- Ho, Bao D., et al.
(författare)
-
Viable/non-viable cell assay using electrokinetic deterministic lateral displacement
- 2019
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Ingår i: 23rd International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2019. - 9781733419000 ; , s. 596-597
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Konferensbidrag (refereegranskat)abstract
- To evaluate the effect of antibiotic drugs, it is important that the cells that are killed can be sorted from the cells that are resistant to the antibiotics. Here we report a simple label-free method for the continuous separation of viable/non-viable cells using Electrokinetic Deterministic Lateral Displacement. In general, this opens up for continuous sorting of a population of cells that is homogeneous in size but heterogeneous in surface charge or dielectric properties, properties that change as a function of viability.
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| 36. |
- Hochstetter, Axel, et al.
(författare)
-
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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| 37. |
- Holm, Stefan H., et al.
(författare)
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A high-throughput deterministic lateral displacement device for rapid and sensitive field-diagnosis of sleeping sickness
- 2012
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Ingår i: Proceedings of the 16th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2012. - 9780979806452 ; , s. 530-532
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Konferensbidrag (refereegranskat)abstract
- We present a simple and rapid microfluidic device capable of extracting and concentrating the parasite causing the fatal disease sleeping sickness (SS) from blood. The device is based on deterministic lateral displacement (DLD) and constructed with a single inlet with flow induced by an ordinary syringe. The simplicity is crucial as the device is intended for use in the resource depraved areas where the disease is endemic. With only one inlet an intricate design with multiple depths has been utilized to create a cell free stream from the blood plasma into which the parasites are forced and subsequently collected in a detection region. In order to maximize the sample volume up to 10 device layers were stacked on top of each other which resulted in a throughput of ∼10 μL/min. This allowed for an approximate time per test of below 15 min.
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| 38. |
- Holm, Stefan H., et al.
(författare)
-
Combined density and size-based sorting in deterministic lateral displacement devices
- 2013
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Ingår i: 17th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2013. - 9781632666246 ; 2, s. 1224-1226
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Konferensbidrag (refereegranskat)abstract
- We present a deterministic-lateral-displacement (DLD) device that extends the capabilities of this traditionally sizebased particle separation technique to also be sensitive to density. By the use of T-shaped posts instead of the normally cylindrical posts the particle trajectory through the device will be a function of its vertical position which in turn is determined by the buoyancy of the particles. The potential lies in fast sorting of complex biological samples together with diagnosis and treatment-monitoring of diseases affecting cell-density, eg. cancer, sickle-cell anemia and malaria. We demonstrate proof-of-principle of combined size-and-density-based sorting, specifically particles of identical size but different density.
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| 39. |
- Holm, Stefan H., et al.
(författare)
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Density-based particle fractionation
- 2014
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Ingår i: 18th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2014. - 9780979806476 ; , s. 288-290
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Konferensbidrag (refereegranskat)abstract
- We present a label-free method capable of rapidly sorting particles based on their densities. Our device relies on deterministic lateral displacement (DLD) and achieves density fractionation by the use of T-shaped posts. By combining it with a lateral density gradient we achieve a density separation that is independent of size within a range given by the device geometry. Herein we present a proof-of-principle method which, in comparison to traditional density-separation techniques, is suitable for lab-on-a-chip environment.
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| 40. |
- Holm, Stefan H., et al.
(författare)
-
Microfluidic Particle Sorting in Concentrated Erythrocyte Suspensions
- 2019
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Ingår i: Physical Review Applied. - 2331-7019. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- An important step in diagnostics is the isolation of specific cells and microorganisms of interest from blood. Since such bioparticles are often present at very low concentrations, throughput needs to be as high as possible. In addition, to ensure simplicity, a minimum of sample preparation is important. Therefore, sorting schemes that function for whole blood are highly desirable. Deterministic lateral displacement (DLD) devices have proven to be very precise and versatile in terms of a wide range of sorting parameters. To better understand how DLD devices perform for blood as the hematocrit increases, we carry out measurements and simulations for spherical particles in the micrometer range which move through DLD arrays for different flow velocities and hematocrits ranging from pure buffer to concentrated erythrocyte suspensions mimicking whole blood. We find that the separation function of the DLD array is sustained even though the blood cells introduce a shift in the trajectories and a significant dispersion for particles whose diameters are close to the critical size in the device. Simulations qualitatively replicate our experimental observations and help us identify fundamental mechanisms for the effect of hematocrit on the performance of the DLD device.
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