| 1. |
- McGinn, Steven, et al.
(författare)
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New Technologies for DNA analysis-A review of the READNA Project.
- 2016
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Ingår i: New Biotechnology. - : Elsevier BV. - 1876-4347 .- 1871-6784.
-
Forskningsöversikt (refereegranskat)abstract
- The REvolutionary Approaches and Devices for Nucleic Acid analysis (READNA) project received funding from the European Commission for 4 1/2 years. The objectives of the project revolved around technological developments in nucleic acid analysis. The project partners have discovered, created and developed a huge body of insights into nucleic acid analysis, ranging from improvements and implementation of current technologies to the most promising sequencing technologies that constitute a 3(rd) and 4(th) generation of sequencing methods with nanopores and in situ sequencing, respectively.
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| 2. |
- Adolfsson, Karl, et al.
(författare)
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Fluorescent Nanowire Heterostructures as a Versatile Tool for Biology Applications
- 2013
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 13:10, s. 4728-4732
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Tidskriftsartikel (refereegranskat)abstract
- Nanowires are increasingly used in biology, as sensors, as injection devices, and us model systems for toxicity studies. Currently, in situ visualization of nanowires in biological media is done using organic dyes, which a;:e prone to photobleaching, or using microscopy methods which either yield poor resolution or require a sophisticated setup. Here we show that inherently fluorescent nanowire axial heterostructnies c:an be used to localize and identify nanowires in cells and tissue; By synthesizing GaP GaInP nanowire heterostructures, with nonfluorescent GaP segments and fluorescent GaInP segments, we created a barcode labeling system enabling the distinction of the nanowire morphological and chemical properties using fluorescence microscopy. The GaInP photoluminescence stability, combined with the fact that the nanowires can be coated with different materials while retaining their fluorescence, make these nanowires promising tools for biological and nanotoxicological studies.
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| 3. |
- Akbari, Elham, et al.
(författare)
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SEPARATION OF CLUSTERS OF GROUP A STREPTOCOCCI USING DETERMINISTIC LATERAL DISPLACEMENT
- 2021
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Ingår i: MicroTAS 2021 - 25th International Conference on Miniaturized Systems for Chemistry and Life Sciences. - 9781733419031 ; , s. 1201-1202
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Konferensbidrag (refereegranskat)abstract
- Differences in morphologies of bacteria and bacteria clusters are known to influence their pathogenicity. However, it is difficult to separate cells and cell clusters based on morphology using standard cell biological methods, making studies of the underlying mechanisms difficult. Here we report a simple label-free method for the continuous separation of clusters of group A streptococci, based on cluster size and morphology, using Deterministic Lateral Displacement (DLD). In general, this opens up for the generation of cell populations with heterogenicity in cluster size and physical properties.
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| 4. |
- Akbari, Elham, et al.
(författare)
-
SEPARATION OF SINGLETS AND CLUSTERS OF GROUP A STREPTOCOCCI USING DETERMINISTIC LATERAL DISPLACEMENT AND FILTER SONICATION
- 2022
-
Ingår i: MicroTAS 2022 - 26th International Conference on Miniaturized Systems for Chemistry and Life Sciences. - 9781733419048 ; , s. 306-307
-
Konferensbidrag (refereegranskat)abstract
- Differences in morphologies of bacteria and bacteria clusters are thought to contribute to their virulence and colonization. However, the conventional standard cell biological methods cannot separate bacteria and bacteria clusters based on their morphologies and sizes, making studies of the underlying mechanisms difficult. Here we report a simple label-free method for the continuous separation of singlets and clusters, of group A streptococci, based on their size and morphology, using Deterministic Lateral Displacement and filter-sonication. In general, this opens up for the generation of cell populations with heterogenicity in cluster size and physical properties.
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| 5. |
- Al-Fandi, M, et al.
(författare)
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Nano-engineered living bacterial motors for active microfluidic mixing.
- 2010
-
Ingår i: IET Nanobiotechnology. - : Institution of Engineering and Technology (IET). - 1751-875X .- 1751-8741. ; 4:3, s. 61-71
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Tidskriftsartikel (refereegranskat)abstract
- Active micromixers with rotating elements are attractive microfluidic actuators in many applications because of their mixing ability at a short distance. However, miniaturising the impeller design poses technical challenges including the fabrication and driving means. As a possible solution inspired by macro magnetic bar-stirrers, this study proposes the use of tethered, rotating bacteria as mixing elements. A tethered cell is a genetically engineered, harmless Escherichia coli (E. coli) attached to a surface by a single, shortened flagellum. The tethered flagellum acts as a pivot around which the entire cell body smoothly rotates. Videomicroscopy, image analysis and computational fluid dynamics (CFD) are utilised to demonstrate a proof-of-concept for the micro mixing process. Flow visualisation experiments show that a approximately 3 [micro sign]m long tethered E. coli rotating at approximately 240 rpm can circulate a 1 [micro sign]m polystyrene bead in the adjacent area at an average speed of nearly 4 [micro sign]m/s. The Peclet (Pe(b)) number for the stirred bead is evaluated to approximately 4. CFD simulations show that the rotary motion of a tethered E. coli rotating at 240 rpm can generate fluid velocities, up to 37 [micro sign]m/s bordering the cell envelop. Based on these simulations, the Strouhal number (St) is calculated to about 2. This hybrid bio-inorganic micromxer could be used as a local, disposable mixer.
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| 6. |
- Alizadehheidari, Mohammadreza, 1987, et al.
(författare)
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Nanoconfined Circular and Linear DNA: Equilibrium Conformations and Unfolding Kinetics
- 2015
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Ingår i: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 48:3, s. 871-878
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Tidskriftsartikel (refereegranskat)abstract
- Studies of circular DNA confined to nanofluidic channels are relevant both from a fundamental polymer-physics perspective and due to the importance of circular DNA molecules in vivo. We here observe the unfolding of confined DNA from the circular to linear configuration as a light-induced double-strand break occurs, characterize the dynamics, and compare the equilibrium conformational statistics of linear and circular configurations. This is important because it allows us to determine to what extent existing statistical theories describe the extension of confined circular DNA. We find that the ratio of the extensions of confined linear and circular DNA configurations increases as the buffer concentration decreases. The experimental results fall between theoretical predictions for the extended de Gennes regime at weaker confinement and the Odijk regime at stronger confinement. We show that it is possible to directly distinguish between circular and linear DNA molecules by measuring the emission intensity from the DNA. Finally, we determine the rate of unfolding and show that this rate is larger for more confined DNA, possibly reflecting the corresponding larger difference in entropy between the circular and linear configurations.
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| 7. |
- Alizadehheidari, Mohammadreza, et al.
(författare)
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Nanoconfined Circular DNA
- 2014
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Ingår i: Biophysical Journal. - : Elsevier BV. - 0006-3495 .- 1542-0086. ; 106:2, s. 274A-274A
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Nanofluidic channels have become a versatile tool to manipulate single DNA molecules. They allow investigation of confined single DNA molecules from a fundamental polymer physics perspective as well as for example in DNA barcoding techniques.
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| 8. |
- Alizadehheidari, Mohammadreza, 1987, et al.
(författare)
-
Unfolding of nanoconfined circular DNA
- 2015
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Ingår i: BIOPHYSICAL JOURNAL. - : Elsevier BV. - 0006-3495 .- 1542-0086. ; 108:2 Supplement 1
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 9. |
- Barrett, Michael P., et al.
(författare)
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Microfluidics-based approaches to the isolation of African trypanosomes
- 2017
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Ingår i: Pathogens. - : MDPI AG. - 2076-0817. ; 6:4
-
Forskningsöversikt (refereegranskat)abstract
- African trypanosomes are responsible for significant levels of disease in both humans and animals. The protozoan parasites are free-living flagellates, usually transmitted by arthropod vectors, including the tsetse fly. In the mammalian host they live in the bloodstream and, in the case of human-infectious species, later invade the central nervous system. Diagnosis of the disease requires the positive identification of parasites in the bloodstream. This can be particularly challenging where parasite numbers are low, as is often the case in peripheral blood. Enriching parasites from body fluids is an important part of the diagnostic pathway. As more is learned about the physicochemical properties of trypanosomes, this information can be exploited through use of different microfluidic-based approaches to isolate the parasites from blood or other fluids. Here, we discuss recent advances in the use of microfluidics to separate trypanosomes from blood and to isolate single trypanosomes for analyses including drug screening.
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| 10. |
- Beck, Marc, et al.
(författare)
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Fabrication and characterization of a molecular adhesive layer for micro- and nanofabricated electrochemical electrodes
- 2002
-
Ingår i: 7th International Conference on Nanometer-Scale Science and Technology and 21st European Conference on Surface Science.
-
Konferensbidrag (refereegranskat)abstract
- When making nanoelectrodes for applications in liquid cells it is plausible that the less noble metal layer may be negatively affected, i.e. it will be etched away leading to very unstable conditions during operation. Here we describe a dry method to produce such a molecular layer consisting of mercaptopropyltriethoxysilane (MPTS) making it possible to controllable and reproducibly form a covalently bound monolayer of MPTS to the SiO2 surface. From Photoelectron Spectroscopy measurements we could conclude that the layer thickness corresponds to a monolayer. We have electrochemically characterized such electrodes by cyclic voltammetry. Furthermore, we have successfully patterned such layers at both micro- and nanometer scale showing the possibilities to fabricate chemically selective and active areas that may be used in various applications
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| 11. |
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| 12. |
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| 13. |
- Beech, Jason P., et al.
(författare)
-
Active Posts in Deterministic Lateral Displacement Devices
- 2019
-
Ingår i: Advanced Materials Technologies. - : Wiley. - 2365-709X. ; 4:9
-
Tidskriftsartikel (refereegranskat)abstract
- Using electrically connected metal-coated posts in a deterministic lateral displacement (DLD) device and applying electric fields, electrokinetics is used to tune separations, significantly decrease the critical size for separation, and increase the dynamic range with switching times on the order of seconds. The strength of DLD stems from its binary behavior. To first approximation, particles move in one out of two trajectories based on their effective size. For particles that are close to the threshold size, a small external force is sufficient to nudge the particles from one trajectory to another. The devices consist of arrays of cylindrical metal-coated SU-8 posts connected by an underlying metal layer. This allows the application of voltages at the post surfaces and the generation of electric field gradients between neighboring posts, causing polarizable particles to experience a dielectrophoretic (DEP) force. This force, which depends on the volume and polarizability of the particle, can be made sufficient to push particles from one trajectory into another. In this way, the critical size in a device, normally fixed by the geometry, can be tuned. What's more, adding DEP in this way allows for the simultaneous creation of multiple size fractions.
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| 14. |
- Beech, Jason P., et al.
(författare)
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Capillary driven separation on patterned surfaces
- 2009
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Ingår i: Proceedings of Conference, MicroTAS 2009 - The 13th International Conference on Miniaturized Systems for Chemistry and Life Sciences. - 9780979806421 ; , s. 785-787
-
Konferensbidrag (refereegranskat)abstract
- Deterministic lateral displacement (DLD) is a powerful bimodal separation scheme [1] based on fluid flow through regular obstacle arrays that in its basic embodiment sends suspended particles in two different directions as a function of size. We show that without the need to seal devices and without the need for fluidic connections or pumps, particle separation can be achieved by the passive flow of a sample over a patterned surface. Risk of clogging is minimized by the movement of large particles above the obstacle array. Suitable application areas include blood fractionation and analysis of drinking water. 0
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| 15. |
- Beech, Jason P., et al.
(författare)
-
Cell morphology and deformability in deterministic lateral displacement devices
- 2011
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Ingår i: 15th International Conference on Miniaturized Systems for Chemistry and Life Sciences 2011, MicroTAS 2011. - 9781618395955 ; 2, s. 1355-1357
-
Konferensbidrag (refereegranskat)abstract
- Deterministic Lateral Displacement (DLD) devices have been used to separate particles based on size [1] and shape [2]. Here we show how DLD devices can also be used to separate particles based on their ability to deform under shear forces. Varying experimental conditions allows us to vary the relative contributions of size, morphology and deformability. The ability to distinguish between cells based on deformability with high resolution and throughput, in cheap and simple devices, could find highly interesting and relevant applications, for example in the detection of circulating tumor cells or malaria-infected blood cells.
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| 16. |
- Beech, Jason P., et al.
(författare)
-
Electrokinetic wall effect mechanisms and applications
- 2020
-
Ingår i: MicroTAS 2020 - 24th International Conference on Miniaturized Systems for Chemistry and Life Sciences. - 9781733419017 ; , s. 42-43
-
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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| 17. |
- Beech, Jason P., et al.
(författare)
-
Gravitationally driven deterministic lateral displacement devices
- 2009
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Ingår i: Proceedings of Conference, MicroTAS 2009 - The 13th International Conference on Miniaturized Systems for Chemistry and Life Sciences. - 9780979806421 ; , s. 779-781
-
Konferensbidrag (refereegranskat)abstract
- Deterministic lateral displacement (DLD) is a powerful bimodal separation scheme [1] based on regular obstacle arrays that in its basic embodiment sends particles in two different directions as a function of size. We add functionality to the technique by including gravitational forces, as a perturbation to particles transported by fluid flow, and as a way of transporting the particles through a stationary fluid.
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| 18. |
- Beech, Jason P., et al.
(författare)
-
Morphology-based sorting-blood cells and parasites
- 2010
-
Ingår i: 14th International Conference on Miniaturized Systems for Chemistry and Life Sciences 2010, MicroTAS 2010. - 9781618390622 ; 2, s. 1343-1345
-
Konferensbidrag (refereegranskat)abstract
- Morphology represents a hitherto unexploited source of specificity in microfluidic particle separation and may serve as the basis for label-free particle fractionation. There is a wealth of morphological changes in blood cells due to a wide range of clinical conditions, diseases, medication and other factors. Also, blood-borne parasites differ in morphology from blood cells. We present the use of Deterministic Lateral Displacement to create a chip-based, label-free diagnostic tool, capable of harvesting some of the wealth of information locked away in red blood cell morphology. We also use the device to separate the parasites that cause sleeping sickness from blood.
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| 19. |
- Beech, Jason P., et al.
(författare)
-
Sample preparation for single-cell whole chromosome analysis
- 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. 998-999
-
Konferensbidrag (refereegranskat)abstract
- In this work we present an integrated system for whole chromosome analysis of single bacterium. Using whole genome barcoding techniques, which offer direct and rapid microscopic visualization of the entire genome in one field-of-view, we aim to rapidly identify individual bacterium. We are developing our device to achieve the crucial, and difficult process of isolating a bacterium, removing the DNA in one piece and transferring it to a nano-channel for visualisation. In order to achieve control over the bacteria we encapsulate them in agarose, using flow focusing. The encapsulated bacteria can then be transported in microchannels to proximity with the nanochannels and then chemically lysis can be performed. Following lysis the intact genome can be extracted and transferred to the meandering nanochannel for analysis. We believe this device holds the potential to significantly decrease analysis times for single cell, whole genome analysis with the potential of opening up for automated, high-throughput genome analysis in microfluidic systems.
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| 20. |
- Beech, Jason P., et al.
(författare)
-
Separation of pathogenic bacteria by chain length
- 2018
-
Ingår i: Analytica Chimica Acta. - : Elsevier BV. - 0003-2670 .- 1873-4324. ; 1000, s. 223-231
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Tidskriftsartikel (refereegranskat)abstract
- Using Deterministic Lateral Displacement devices optimized for sensitivity to particle length, we separate subpopulations of bacteria depending on known properties that affect their capability to cause disease (virulence). For the human bacterial pathogen Streptococcus pneumoniae, bacterial chain length and the presence of a capsule are known virulence factors contributing to its ability to cause severe disease. Separation of cultured pneumococci into subpopulations based on morphological type (single cocci, diplococci and chains) will enable more detailed studies of the role they play in virulence. Moreover, we present separation of mixed populations of almost genetically identical encapsulated and non-encapsulated pneumococcal strains in our device.
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| 21. |
- Beech, Jason P., et al.
(författare)
-
Shape-based particle sorting - A new paradigm in microfluidics
- 2009
-
Ingår i: Proceedings of Conference, MicroTAS 2009 - The 13th International Conference on Miniaturized Systems for Chemistry and Life Sciences. - 9780979806421 ; , s. 800-802
-
Konferensbidrag (refereegranskat)abstract
- Conventional fractionation techniques fail to fully benefit from the variety in morphology and shape that is found among biological particles. Although light scattering in conventional FACS gives some information on the size and morphology of a particle, it is generally not capable of giving a definite number on specified dimensions of a small object. We demonstrate an approach where we select which dimension of a particular object is used to determine its trajectory through an obstacle course and thereby sort not merely with respect to hydrodynamic radius but rather with respect to e.g. thickness, length or width.
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| 22. |
- Beech, Jason P., et al.
(författare)
-
Sorting bacteria by chain length - A factor of virulence?
- 2016
-
Ingår i: 20th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2016. - 9780979806490 ; , s. 250-251
-
Konferensbidrag (refereegranskat)abstract
- Using Deterministic Lateral Displacement (DLD), we are able to separate bacteria by their size and their chain length. This separation enables the study of these properties as factors of virulence.
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| 23. |
- Beech, Jason P., et al.
(författare)
-
The separation and identification of parasite eggs from horse feces
- 2019
-
Ingår i: 23rd International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2019. - 9781733419000 ; , s. 602-603
-
Konferensbidrag (refereegranskat)abstract
- Freely grazing horses are at risk of infection by parasites such as Parascaris equorum (roundworm), Strongylus spp. (large bloodworms), Cyathostomes (small bloodworms), and Anoplochephala perfoliata (tapeworms). Mixed infections are common and diagnosis is based on demonstrations of eggs in feces followed by identification of larvae after fecal culture. Drug resistance is a growing problem, not least because treatments tend to be cheaper than diagnosis and “just in case” treatments common. There is a need for improved methods that are easy to use, rapid and cheap. Furthermore, a successful approach may find use with other livestock such as ruminants and pigs.
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| 24. |
- Beech, Jason P., et al.
(författare)
-
The separation of nano-sized particles in micro-scaled post arrays
- 2019
-
Ingår i: 23rd International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2019. - 9781733419000 ; , s. 10-11
-
Konferensbidrag (refereegranskat)abstract
- The precise separation of nanoscale particles has proven challenging due to diffusion and the need to use nanoscale devices. We show the separation of particles in the 100 nm size range in Deterministic Lateral Displacement (DLD) devices with feature sizes in the 10 µm size range. We achieve this using Dielectrophoretic (DEP) forces, generated between the metal coated posts that act as active electrodes. This opens up for the separation of submicron particles based not only on size but also on electric and dielectric properties.
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| 25. |
- Beech, Jason P., et al.
(författare)
-
Throughput through thin-film fluidics
- 2008
-
Ingår i: ; , s. 1492-1494
-
Konferensbidrag (refereegranskat)abstract
- We demonstrate fluidics realized in thin film plastic foils patterned using roll-toroll nanoimprinting lithography (rrNIL). Realizing fluidics devices in thin plastic foils opens up for parallel operation in stacked devices. It also provides a convenient format for storage and distribution of the devices.
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| 26. |
- Beech, Jason P., et al.
(författare)
-
Tipping the balance with dielectrophoretic forces - An electric deterministic lateral displacement device
- 2008
-
Ingår i: ; , s. 95-97
-
Konferensbidrag (refereegranskat)abstract
- We present experimental results and simulations on a simple method for tunable particle separation based on a combination of Deterministic Lateral Displacement (DLD) and Insulator Based Dielectrophoresis (I-DEP). Rather than deriving its tunability from its elastic properties[1], our present device uses an applied AC field to perturb the particle trajectories in the pressure-driven flow and is thereby capable of scanning the critical size over a range of factor two. Potential benefits include: extended dynamic range, facilitated fabrication and less clogging for given particle sizes, and combination of the precision afforded by DLD with the versatility of DEP.
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| 27. |
- Beech, Jason P., et al.
(författare)
-
Tunable separation and DNA manipulation in metal coated pillar arrays
- 2018
-
Ingår i: 22nd International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2018. - 9781510897571 ; 4, s. 2090-2093
-
Konferensbidrag (refereegranskat)abstract
- Implementing electrically connected metal-coated posts in a Deterministic Lateral Displacement (DLD) device and applying electric fields, we use electrokinetics to achieve tunable particle separations and to trap and manipulate DNA. The strength of DLD stems from its typically binary behavior. Particles move in one out of two trajectories based on their effective size. For particles that are close to the threshold size, a minute external force is sufficient to nudge the particles from one trajectory to another. Dielectrophoresis (DEP) provides such a force and also gives specificity based on the dielectric properties of the particles.
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| 28. |
- Beech, Jason P, et al.
(författare)
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Using symmetry to control viscoelastic waves in pillar arrays
- 2023
-
Ingår i: RSC Advances. - 2046-2069. ; 13:45, s. 31497-31506
-
Tidskriftsartikel (refereegranskat)abstract
- Solutions of macromolecules exhibit viscoelastic properties and unlike Newtonian fluids, they may break time-reversal symmetry at low Reynolds numbers resulting in elastic turbulence. Furthermore, under some conditions, instead of the chaotic turbulence, the result is large-scale waves in the form of cyclic spatial and temporal concentration variations, as has been shown for macromolecular DNA flowing in microfluidic pillar arrays. We here demonstrate how altering the symmetry of the individual pillars can be used to influence the symmetry of these waves. We control the extent of instabilities in viscoelastic flow by leveraging the effects of the symmetry of the pillars on the waves, demonstrating suppressed viscoelastic fluctuations with relevance for transport and sorting applications, or conversely opening up for enhanced viscoelasticity-mediated mixing. The onset of waves, which changes flow resistance, occurs at different Deborah numbers for flow in different directions through the array of triangular pillars, thus breaking the symmetry of the flow resistance along the device, opening up for using the occurrence of the waves to construct a fluidic diode.
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| 29. |
- Beech, Jason, et al.
(författare)
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Sorting cells by size, shape and deformability
- 2012
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Ingår i: Lab on a Chip. - : Royal Society of Chemistry (RSC). - 1473-0197 .- 1473-0189. ; 12, s. 1048-1051
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Tidskriftsartikel (refereegranskat)abstract
- While size has been widely used as a parameter in cellular separations, in this communication we show how shape and deformability, a mainly untapped source of specificity in preparative and analytical microfluidic devices can be measured and used to separate cells. © 2012 The Royal Society of Chemistry.
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| 30. |
- Beech, Jason, et al.
(författare)
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Stretching the limits of separation
- 2006
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Ingår i: Book of abstracts: Intl Conf on Nanosci and Technol, Basel, Switzerland (2006).
-
Konferensbidrag (refereegranskat)
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| 31. |
- Beech, Jason, et al.
(författare)
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Tipping the balance of deterministic lateral displacement devices using dielectrophoresis.
- 2009
-
Ingår i: Lab on a Chip. - : Royal Society of Chemistry (RSC). - 1473-0189 .- 1473-0197. ; 9:18, s. 2698-2706
-
Tidskriftsartikel (refereegranskat)abstract
- We report the use of dielectrophoresis (DEP) to achieve tunability, improve dynamic range and open up for the separation of particles with regard to parameters other than hydrodynamic size in deterministic lateral displacement (DLD) devices. DLD devices have been shown capable of rapidly and continuously separating micrometer sized plastic spheres by size with a resolution of 20 nm in diameter and of being able to handle the separation of biological samples as wide ranging as bacterial artificial chromosomes and blood cells. DEP, while not exhibiting the same resolution in size separation as DLD, has the benefit of being easy to tune and can, by choosing the frequency, be used to probe a variety of particle properties. By combining DLD and DEP we open up for the advantages, while avoiding the drawbacks, of the two techniques. We present a proof of principle in which the critical size for separation of polystyrene beads is tuned in the range 2-6 microm in a single device by the application of moderate (100 V cm(-1)), low frequency (100 Hz) AC electric fields. The behaviour of the device was further investigated by performing simulations of particle trajectories, the results of which were in good qualitative agreement with experiments, indicating the potential of the method for tunable, high-resolution separations with respect to both size and polarisability.
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| 32. |
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| 33. |
- Beech, Jason, et al.
(författare)
-
Tuneable separation in elastomeric microfluidics devices.
- 2008
-
Ingår i: Lab on a Chip. - : Royal Society of Chemistry (RSC). - 1473-0189 .- 1473-0197. ; 8:5, s. 657-659
-
Tidskriftsartikel (refereegranskat)abstract
- We describe how the elastomeric properties of PDMS (polydimethylsiloxane) can be utilised to achieve tuneable particle separation in Deterministic Lateral Displacement devices via strain controlled alteration of inter-obstacle distances, a development that opens up new avenues toward more effective separation of particles in microfluidics devices.
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| 34. |
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| 35. |
- Bilenberg, B, et al.
(författare)
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Topas-based lab-on-a-chip microsystems fabricated by thermal nanoimprint lithography
- 2005
-
Ingår i: Journal of Vacuum Science and Technology B. - : American Vacuum Society. - 1520-8567. ; 23:6, s. 2944-2949
-
Tidskriftsartikel (refereegranskat)abstract
- We, present a one-step technology for fabrication of Topas-based lab-on-a-chip (LOC) microsysterris by the use of thermal nanoimprint lithography (NIL). The technology is demonstrated by the fabrication of two working devices: a particle separator and a LOC with integrated optics for absorbance measurements. These applications demonstrate the fabrication of millimeter to micrometer-sized structures in one lithographic step. The use of NIL makes the technology easily scalable into the nanometer regime by the use of a suitable lithographic technique in the fabrication of the stamp. Processing issues such as environmental stress cracking of the Topas and the requirements to anti-sticking layers on the stamp when imprinting into Topas are discussed.
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| 36. |
- Bogas, Diana, et al.
(författare)
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Applications of optical DNA mapping in microbiology
- 2017
-
Ingår i: BioTechniques. - : Future Science Ltd. - 0736-6205 .- 1940-9818. ; 62:6, s. 255-267
-
Forskningsöversikt (refereegranskat)abstract
- Optical mapping (OM) has been used in microbiology for the past 20 years, initially as a technique to facilitate DNA sequence-based studies; however, with decreases in DNA sequencing costs and increases in sequence output from automated sequencing platforms, OM has grown into an important auxiliary tool for genome assembly and comparison. Currently, there are a number of new and exciting applications for OM in the field of microbiology, including investigation of disease outbreaks, identification of specific genes of clinical and/or epidemiological relevance, and the possibility of single-cell analysis when combined with cell-sorting approaches. In addition, designing lab-on-a-chip systems based on OM is now feasible and will allow the integrated and automated microbiological analysis of biological fluids. Here, we review the basic technology of OM, detail the current state of the art of the field, and look ahead to possible future developments in OM technology for microbiological applications.
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| 37. |
- Cao, Han, et al.
(författare)
-
Fabrication of 10 nm enclosed nanofluidic channels
- 2002
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 81:1, s. 174-176
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Tidskriftsartikel (refereegranskat)abstract
- We made uniform arrays of nanometer scale structures using nanoimprint lithography over large areas (100 mm wafers). The nanofluidic channels were further narrowed and sealed by techniques that are based on nonuniform deposition. The resulting sealed channels have a cross section as small as 10 nm by 50 nm, of great importance for confining biological molecules into ultrasmall spaces. These techniques can be valuable fabrication tools for Nanoelectromechanical Systems and Micro/Nano Total Analysis Systems.
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| 38. |
- Cao, Han, et al.
(författare)
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Gradient nanostructures for interfacing microfluidics and nanofluidics
- 2002
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 81:16, s. 3058-3060
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Tidskriftsartikel (refereegranskat)abstract
- It is difficult to introduce long genomic DNA molecules into nanometer scale fluidic channels directly from the macroscale world because of the steep entropic barrier caused by necessary stretching of the polymer. We present a very simple technique using optical lithography to fabricate continuous spatial gradient structures which smoothly narrow the cross section of a volume from the micron to the nanometer length scale, greatly reducing the local entropic barrier to nanochannel entry. This technique, diffraction gradient lithography, can be very valuable for the fabrication of micro/nano total analysis systems.
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| 39. |
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| 40. |
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| 41. |
- Dahlin, Andreas, et al.
(författare)
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Improving the instrumental resolution of sensors based on localized surface plasmon resonance
- 2006
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 1520-6882 .- 0003-2700. ; 78:13, s. 4416-4423
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Tidskriftsartikel (refereegranskat)abstract
- The colorimetric variations induced upon changes in interfacial refractive index of nanoscale noble metal structures exhibiting localized surface plasmon resonance (LSPR) provides a convenient means of label-free, affinity-based detection of biomolecular recognition reactions. However, despite being similar in nature to conventional SPR, LSPR has so far suffered from significantly lower data quality in terms of its signal-to-noise ratio (S/N) in typical biomolecular recognition analysis. In this work, generic data analysis algorithms and a simple experimental setup that provide a S/N upon protein binding that is comparable to that of state-of-the art SPR systems are presented. Specifically, it is demonstrated how temporal variations ( rate similar to 0.5 Hz) in parameters proportional to the resonance peak position can be recorded simultaneously, yielding a peak position precision of < 5 x 10(-4) nm and an extinction noise level of < 5 x 10(-6) absorbance units (Abs). This, in turn, is shown to provide a S/N of similar to 2000 ( equivalent to a detection limit of < 0.1 ng/cm(2)) for typical protein binding reactions. Furthermore, the importance of utilizing changes in both peak position and magnitude is highlighted by comparing different LSPR active noble metal architectures that respond differently to bulk and interfacial refractive index changes.
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| 42. |
- Emilsson, Gustav, 1989, et al.
(författare)
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Identifying bacteria using DNA binding maps
- 2013
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Ingår i: 17th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2013; Freiburg; Germany; 27 October 2013 through 31 October 2013. - 9781632666246 ; 1, s. 473-475
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Konferensbidrag (refereegranskat)abstract
- We have developed an assay, based on nanofluidic channels and fluorescence microscopy, for optical mapping of DNA based on competitive binding between two molecules - one fluorescent and one sequence selective. From the experimental data we can extract binding constants for the two competing DNA binders, which may be subsequently used to calculate a theoretical reference map of any DNA with known sequence. The goal is to create a method for fast identification of bacteria from single DNA molecules without the need for additional cultivation or amplification. We here demonstrate a proof-of-principle experiment on phage DNA and furthermore show that the method can be used to distinguish between two strains of E. coli DNA and to map pieces of DNA onto the full genome.
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| 43. |
- Faridi, Muhammad Asim
(författare)
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Bioparticle Manipulation using Acoustophoresis and Inertial Microfluidics
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Despite the many promising advances made in microfluidics, sample preparation remains the single largest challenge and bottleneck in the field of miniaturised diagnostics. This thesis is focused on the development of sample preparation methods using active and passive particle manipulation techniques for point of care diagnostic applications. The active technique is based on acoustophoresis (acoustic manipulation) while the passive method is based on inertial microfluidics (hydrodynamic manipulation). In paper I, acoustic capillary-based cavity resonator was used to study aggregation of silica and polystyrene particles. We found that silica particles show faster aggregation time (5.5 times) and larger average area of aggregates (3.4 times) in comparison to polystyrene particles under the same actuation procedure. The silica particles were then used for acoustic based bacteria up-concentration. In paper II, a microfluidic-based microbubbles activated acoustic cell sorting technique was developed for affinity based cell separation. As a proof of principle, separation of cancer cell line in a suspension with better than 75% efficiency is demonstrated. For the passive sample preparation, inertial and elasto-inertial microfluidic approach that uses geometry-induced hydrodynamic forces for continuous size-based sorting of particles in a flow-through fashion were studied and applied for blood processing (paper III-V). In paper III, a simple ushaped curved channel was used for inertial microfluidics based enrichment of white blood cells from diluted whole blood. A filtration efficiency of 78% was achieved at a flow rate of 2.2 ml/min. In paper IV, elasto-inertial microfluidics where viscoelastic flow enables size-based migration of cells into a non- Newtonian solution, was used to continuously separate bacteria from unprocessed whole blood for sepsis diagnostics. Bacteria were continuously separated at an efficiency of 76% from undiluted whole blood sample. Finally, in paper V, the inertial and elasto-inertial techniques were combined with a detection platform to demonstrate an integrated miniaturized flow cytometer. The all-optical-fiber technology based system allows for simultaneous measurements of fluorescent and scattering data at 2500 particles/s. The use of inertial and acoustic techniques for sample preparation and development of an integrated detection platform may allow for further development and realization of point of care testing (POCT) systems.
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| 44. |
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| 45. |
- Freitag, C., et al.
(författare)
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Visualizing the entire DNA from a chromosome in a single frame
- 2015
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Ingår i: Biomicrofluidics. - : AIP Publishing. - 1932-1058. ; 9:4
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Tidskriftsartikel (refereegranskat)abstract
- The contiguity and phase of sequence information are intrinsic to obtain complete understanding of the genome and its relationship to phenotype. We report the fabrication and application of a novel nanochannel design that folds megabase lengths of genomic DNA into a systematic back-and-forth meandering path. Such meandering nanochannels enabled us to visualize the complete 5.7 Mbp (1mm) stained DNA length of a Schizosaccharomyces pombe chromosome in a single frame of a CCD. We were able to hold the DNA in situ while implementing partial denaturation to obtain a barcode pattern that we could match to a reference map using the Poland-Scheraga model for DNA melting. The facility to compose such long linear lengths of genomic DNA in one field of view enabled us to directly visualize a repeat motif, count the repeat unit number, and chart its location in the genome by reference to unique barcode motifs found at measurable distances from the repeat. Meandering nanochannel dimensions can easily be tailored to human chromosome scales, which would enable the whole genome to be visualized in seconds. (C) 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.
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| 46. |
- Fritzsche, Joachim, 1977, et al.
(författare)
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A lipid-based passivation scheme for nanofluidics
- 2012
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Ingår i: 16th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2012; Okinawa; Japan; 28 October 2012 through 1 November 2012. - 9780979806452 ; , s. 1876-1878
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Konferensbidrag (refereegranskat)abstract
- Stretching DNA in nanochannels allows for direct, visual studies of genomic DNA at the single molecule level. In order to facilitate the study of the interaction of linear DNA with proteins in nanochannels, we have implemented a highly effective passivation scheme based on lipid bilayers. We show long-term passivation of nanochannel surfaces to several relevant reagents and demonstrate that the performance of the lipid bilayer is significantly better compared to standard bovine serum albumin-based passivation. Moreover, we demonstrate how the passivated devices allow us to monitor single DNA cleavage events during enzymatic degradation.
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| 47. |
- Fritzsche, Michael, et al.
(författare)
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A Highly UV-transparent Fused Silica Biochip for Sensitive Hepatotoxicity Testing by Autofluorescence
- 2014
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Ingår i: Biochip Journal. - : Springer Science and Business Media LLC. - 2092-7843 .- 1976-0280. ; 8:2, s. 115-121
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Tidskriftsartikel (refereegranskat)abstract
- Fabrication and application of a non-fluorescent and UV-transparent microfluidic biochip in fused silica that allows sensitive autofluorescence detection are described. The biochip is particularly useful in cell-based assays where the most informative autofluorescence signals from the cells reside in the ultraviolet spectral range and where plastic labware materials commonly used in cell culture work severely disturb such measurements. In this study the fused silica biochip was used for measuring intrinsic autofluorescence from liver cells in order to assess hepatotoxic effects of drugs. The assessment assay was carried out with the human liver cell line HepG2 under perfusion conditions in the microfluidics of the biochip. The autofluorescence from the.liver cells exposed to quinidine was readily recorded without background disturbance and correlated well with reference toxicity data.
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| 48. |
- Frykholm, Karolin, 1977, et al.
(författare)
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Probing concentration-dependent behavior of DNA-binding proteins on a single-molecule level illustrated by Rad51
- 2013
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Ingår i: Analytical Biochemistry. - : Elsevier BV. - 0003-2697 .- 1096-0309. ; 443:2, s. 261-268
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Tidskriftsartikel (refereegranskat)abstract
- Low throughput is an inherent problem associated with most single-molecule biophysical techniques. We have developed a versatile tool for high-throughput analysis of DNA and DNA-binding molecules by combining microfluidic and dense DNA arrays. We use an easy-to-process microfluidic flow channel system in which dense DNA arrays are prepared for simultaneous imaging of large amounts of DNA molecules with single-molecule resolution. The Y-shaped microfluidic design, where the two inlet channels can be controlled separately and precisely, enables the creation of a concentration gradient across the microfluidic channel as well as rapid and repeated addition and removal of substances from the measurement region. A DNA array stained with the fluorescent DNA-binding dye YOYO-1 in a gradient manner illustrates the method and serves as a proof of concept. We have applied the method to studies of the repair protein Rad51 and could directly probe the concentration-dependent DNA-binding behavior of human Rad51 (HsRad51). In the low-concentration regime used (100 nM HsRad51 and below), we detected binding to double-stranded DNA (dsDNA) without positive cooperativity. (C) 2013 Elsevier Inc. All rights reserved.
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| 49. |
- Ghasemi, Masoomeh, et al.
(författare)
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Separation of deformable hydrogel microparticles in deterministic lateral displacement devices
- 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. 1672-1674
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Konferensbidrag (refereegranskat)abstract
- To better understand how deformable and non-spherical particles behave in sorting devices based on deterministic lateral displacement we generate models of biological particles with tunable size, shape and mechanical properties using stop-flow lithography and we explore how these parameters play a role in our separation devices. Hollow and solid cylinders are compared with respect to their deformability and their overall behavior in the device. Future work will expand the approach to a range of particle shapes and to particles with varied hydrogel composition to independently control the mechanical properties of the material.
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| 50. |
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