| 1. |
- Xavier, Miguel, et al.
(författare)
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Label-free enrichment of primary human skeletal progenitor cells using deterministic lateral displacement
- 2019
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Ingår i: Lab on a Chip. - : Royal Society of Chemistry (RSC). - 1473-0189 .- 1473-0197. ; 19:3, s. 513-523
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Tidskriftsartikel (refereegranskat)abstract
- Skeletal stem cells (SSCs) are present in bone marrow (BM) and offer great potential for bone regenerative therapies. However, in the absence of a unique marker, current sorting approaches remain challenging in the quest for simple strategies to deliver SSCs with consistent regeneration and differentiation capacities. Microfluidics offers the possibility to sort cells marker-free, based on intrinsic biophysical properties. Recent studies indicate that SSCs are stiffer than leukocytes and are contained within the larger cell fraction in BM. This paper describes the use of deterministic lateral displacement (DLD) to sort SSCs based on cell size and stiffness. DLD is a technology that uses arrays of micropillars to sort cells based on their diameter. Cell deformation within the device can change the cell size and affect sorting - here evidenced using human cell lines and by fractionation of expanded SSCs. Following sorting, SSCs remained viable and retained their capacity to form clonogenic cultures (CFU-F), indicative of stem cell potential. Additionally, larger BM cells showed enhanced capacity to form CFU-F. These findings support the theory that SSCs are more abundant within the larger BM cell fraction and that DLD, or other size-based approaches, could be used to provide enriched SSC populations with significant implications for stem cell research and translation to the clinic.
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| 2. |
- Akbari, Elham, et al.
(författare)
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SEPARATION OF SINGLETS AND CLUSTERS OF GROUP A STREPTOCOCCI USING DETERMINISTIC LATERAL DISPLACEMENT AND FILTER SONICATION
- 2022
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Ingår i: MicroTAS 2022 - 26th International Conference on Miniaturized Systems for Chemistry and Life Sciences. - 9781733419048 ; , s. 306-307
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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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| 3. |
- Alizadehheidari, Mohammadreza, 1987, et al.
(författare)
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Unfolding of nanoconfined circular DNA
- 2015
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Ingår i: BIOPHYSICAL JOURNAL. - : Elsevier BV. - 0006-3495 .- 1542-0086. ; 108:2 Supplement 1
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 4. |
- 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
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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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| 5. |
- Beech, Jason P., et al.
(författare)
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Active Posts in Deterministic Lateral Displacement Devices
- 2019
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Ingår i: Advanced Materials Technologies. - : Wiley. - 2365-709X. ; 4:9
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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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| 6. |
- 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
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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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| 7. |
- Beech, Jason P., et al.
(författare)
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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
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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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| 8. |
- 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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| 9. |
- Beech, Jason P., et al.
(författare)
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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
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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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| 10. |
- Beech, Jason P., et al.
(författare)
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Morphology-based sorting-blood cells and parasites
- 2010
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Ingår i: 14th International Conference on Miniaturized Systems for Chemistry and Life Sciences 2010, MicroTAS 2010. - 9781618390622 ; 2, s. 1343-1345
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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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| 11. |
- Beech, Jason P., et al.
(författare)
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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
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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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| 12. |
- Beech, Jason P., et al.
(författare)
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Separation of pathogenic bacteria by chain length
- 2018
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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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| 13. |
- Beech, Jason P., et al.
(författare)
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Shape-based particle sorting - A new paradigm in microfluidics
- 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. 800-802
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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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| 14. |
- Beech, Jason P., et al.
(författare)
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Sorting bacteria by chain length - A factor of virulence?
- 2016
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Ingår i: 20th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2016. - 9780979806490 ; , s. 250-251
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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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| 15. |
- Beech, Jason P., et al.
(författare)
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The separation and identification of parasite eggs from horse feces
- 2019
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Ingår i: 23rd International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2019. - 9781733419000 ; , s. 602-603
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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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| 16. |
- Beech, Jason P., et al.
(författare)
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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
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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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| 17. |
- Beech, Jason P., et al.
(författare)
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Throughput through thin-film fluidics
- 2008
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Ingår i: ; , s. 1492-1494
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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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| 18. |
- Beech, Jason P., et al.
(författare)
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Tipping the balance with dielectrophoretic forces - An electric deterministic lateral displacement device
- 2008
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Ingår i: ; , s. 95-97
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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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| 19. |
- Beech, Jason P., et al.
(författare)
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Tunable separation and DNA manipulation in metal coated pillar arrays
- 2018
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Ingår i: 22nd International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2018. - 9781510897571 ; 4, s. 2090-2093
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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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| 20. |
- Beech, Jason P, et al.
(författare)
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Using symmetry to control viscoelastic waves in pillar arrays
- 2023
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Ingår i: RSC Advances. - 2046-2069. ; 13:45, s. 31497-31506
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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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| 21. |
- 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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| 22. |
- Bilenberg, B, et al.
(författare)
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Topas-based lab-on-a-chip microsystems fabricated by thermal nanoimprint lithography
- 2005
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Ingår i: Journal of Vacuum Science and Technology B. - : American Vacuum Society. - 1520-8567. ; 23:6, s. 2944-2949
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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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| 23. |
- Bogas, Diana, et al.
(författare)
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Applications of optical DNA mapping in microbiology
- 2017
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Ingår i: BioTechniques. - : Future Science Ltd. - 0736-6205 .- 1940-9818. ; 62:6, s. 255-267
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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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| 24. |
- Cao, Han, et al.
(författare)
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Fabrication of 10 nm enclosed nanofluidic channels
- 2002
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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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| 25. |
- 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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