| 1. |
- Cruz, Javier, 1990-, et al.
(författare)
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Stable 3D Inertial Focusing by High Aspect Ratio Curved Microfluidics
- 2021
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Ingår i: Journal of Micromechanics and Microengineering. - : Institute of Physics Publishing (IOPP). - 0960-1317 .- 1361-6439. ; 31
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Tidskriftsartikel (refereegranskat)abstract
- Fine manipulation of particles is essential for the analysis of complex samples such as blood or environmental water, where rare particles of interest may be masked by millions of others. Inertial focusing is amongst the most promising techniques for this task, enabling label-free manipulation of particles with sub-micron resolution at very high flow rates. However, the phenomenon still remains difficult to predict due to the focus position shifting in tortuous ways as function of the channel geometry, flow rate and particle size. Here, we present a new line of microfluidics that exploit inertial focusing in High Aspect Ratio Curved (HARC) microchannels and overcome this limitation. Consisting of a single curved channel, HARC systems provide a highly predictable, single focus position near the centre of the inner wall, largely independent of the flow rate and particle size.An explanation of the mechanism of migration and focus of particles, together with its governing equations, is provided based on simulations in COMSOL Multiphysics and experimental results. HARC microchannels built in silicon-glass were used for experimental validation, achieving a high quality, single focus position for a range of microparticles with sizes of 0.7 - 1 µm and bacterial cells (Escherichia coli). The recovery of 1 µm particles was 99.84% with a factor four in concentration.With a stable focus position, we envision that HARC systems will bring the technology closer to implementation in laboratories for analysis of complex fluids with biological particles like cells and organelles.
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| 2. |
- Jeong, Seung Hee, et al.
(författare)
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Plåster med sträckbara trådlösa givare för medicinsk teknik
- 2015
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Ingår i: Abstracts Medicinteknikdagarna 2015. ; , s. 59-
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Konferensbidrag (refereegranskat)abstract
- Målet med denna presentation är att visa på olika möjligheter för sträckbara trådlösa givare för medicinsk teknik. Vi söker läkare och företag som är intresserade av detta.Elektronikbranschen förutspår en massiv ökning av trådlösa sensorsystem inom en snar framtid och ett ”Sakernas Internet”. En av de stora utvecklingsområdena här är bärbara tillbehör; trådlösa sensornoder i kroppsnära nätverk som kommunicerar med en smartphone. Men det finns en generation efter detta och många förutspår att det kommer att vara nätverk med trådlösa givare och kommunikationsnoder som är i direktkontakt med kroppen, på huden eller som implantat. Det är här töjbar elektronik kommer att sätta sin prägel då dess mjuka, följsamma och sträckbara folier med givare och elektronik erbjuder en oöverträffad mekanisk koppling till vår hud och våra organ.Den mest uppmärksammade tekniken är den s.k. elastiska elektroniken, vilken utgår från ultratunna, och därmed flexibla, integrerade kretsar som överförs till elastiska substrat. Det möjliggör väldigt tunna system som kan ha samma höga upplösning och täthet av komponenter som annan mikroelektronik1. Detta passar väl till mindre strukturer men har flera svagheter vid tillverkning av system där större och tjockare komponenter krävs. Här har vi i stället utvecklat sträckbara kretskort med en flytande metall som ledare och kontakter. De främsta fördelarna med flytande ledare är att en vätska följer med alla formändringar utan motstånd och att små styva komponenter kan modulärt monteras och kontakteras till ledaren utan att kontakter bryts när den utsätts för en större töjning – istället kommer komponentens kontakt att glida på vätskan2. Vi har redan visat att vi idag kan producera avancerade kretsar med flera lager av ledare och monterade små komponenter för olika trådlösa system med töjningsgivare, RFID, trådlös energiöverföring, termoelektriska komponenter, mm.I denna presentation visar vi hur kan tillverka intelligenta och trådlösa sträckbara plåster med olika givare för att läsa av värmeflödet från en kropp. Vi tror dock att det är lätt för oss att göra andra typer av givare eller montera små chip av kommersiella givare och transdermala elektroder för andra medicinska tillämpningar. Vi behöver dock samverka med läkare och medicinsktekniska företag för att välja och pröva de bäst lämpade givarna.
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| 3. |
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| 4. |
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| 5. |
- Ali, M., et al.
(författare)
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Reduced photoluminescence from InGaN/GaN multiple quantum well structures following 40 MeV iodine ion irradiation
- 2009
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Ingår i: Physica. B, Condensed matter. - : Elsevier. - 0921-4526 .- 1873-2135. ; 404:23-24, s. 4925-4928
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Tidskriftsartikel (refereegranskat)abstract
- The effects following ion irradiation of GaN-based devices are still limited. Here we present data on the photoluminescence (PL) emitted from InGaN/GaN multiple quantum well (MQW) structures, which have been exposed to 40 MeV I ion irradiation. The PL is reduced as a function of applied ion fluence, with essentially no PL signal left above 1011 ions/cm2. It is observed that even the ion fluences in the 109 ions/cm2 range have a pronounced effect on the photoluminescence properties of the MQW structures. This may have consequences concerning application of InGaN/GaN MQW’s in radiation-rich environments, in addition to defect build-up during ion beam analysis.
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| 7. |
- Andersson, Martin, et al.
(författare)
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Dynamic pH determination at high pressure of aqueous additive mixtures in contact with dense CO2
- 2018
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Ingår i: Journal of Supercritical Fluids. - : Elsevier BV. - 0896-8446 .- 1872-8162. ; 136, s. 95-101
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Tidskriftsartikel (refereegranskat)abstract
- A system consisting of a high-pressure tolerant microfluidic glass chip, high-speed absorbance imaging, and image processing has been developed to study rapid dynamic events like pH change in a multiphase flow. The system gives both kinetic and quantitative equilibrated information. By tracking the interactions of aqueous additive mixtures and liquid CO2, at 80 bar and 24 °C, under flow, measurement at a given P, T condition is done in 0.25 s. The acidification rate to steady state was found to be mass transport limited, occurring in less than 1 s. For 30 mM of the additives ammonium acetate and ammonium formate, equilibrium pH of 4.5 and 4.1, respectively, was seen. These additives are of key importance in common mobile phases used in SFC.
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| 8. |
- Andersson, Martin, et al.
(författare)
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Microfluidics for High-Pressure Analyses
- 2018
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Ingår i: 12<sup>th</sup> Micronano System Workshop (MSW 2018, May 14-15, 2018, Espoo, Finland). ; , s. 8-8
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Konferensbidrag (refereegranskat)abstract
- When using appropriate materials and microfabrication techniques, the small dimensionsand mechanical stability of microstructured devices allow for processes at high pressureswithout loss in safety. The largest area of applications has been demonstrated in chemistry,where extraction, synthesis and analyses often excel at high densities and high temperatures.These two parameters are accessible through high pressures. Capillary chemistry has beenused since long but, just like in low-pressure applications, there are several advantages in usingmicrofluidic platforms for control of reactions, catalysis, mixing and separation. For example,planar isothermal set-ups, large local variations in geometries, dense form factors, small deadvolumes and precisely positioned microstructures.In analytical systems, we are studying high-pressure components and microsystems forsampling, sample preparation, analyses and fractionation. We will present what drives ourresearch and development: Our experimental set-up with high-pressure pumps, high-speedcamera, sensors, valves, piston-chambers, backpressure regulators, cooling table, etc. How wehave built capability in pumping and valving by the use of stainless steel and paraffinactuation. How we are making high pressure silicon-glass and glass-glass chips with integratedelectrical thin film sensors, using printed circuit boards to ease handling of the chips andintegrating modules. A set of relevant publications are listed below.
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| 9. |
- Bjerketorp, J., et al.
(författare)
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Rapid lab-on-a-chip profiling of human gut bacteria
- 2008
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Ingår i: Journal of Microbiological Methods. - : Elsevier BV. - 0167-7012 .- 1872-8359. ; 72:1, s. 82-90
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Tidskriftsartikel (refereegranskat)abstract
- The human gut microbiota has a substantial impact on human health. Different factors such as disease, diet and drug use can have significant impacts on the gut microbiota. Therefore, it is of interest to have simple, rapid methods for analysis of the composition of the gut microbiota for clinical diagnostic purposes. Since only a minor fraction of the gastrointestinal bacterial community is presently possible to cultivate, molecular approaches are currently the best suited to investigate its composition. However, most of these molecular approaches require technical expertise and expensive equipment to run and they are not routinely available. Ideally, the analyses should be point-of-care options that can be run on a chip. In this study, an existing lab-on-chip (LOC) system for sizing/quantifying DNA was combined with length heterogeneity PCR (LH-PCR), a PCR-based profiling method targeting bacterial 16S rRNA gene sequences, to develop a fast, straightforward, reproducible, and economical method for profiling bacterial communities. The LOC LH-PCR method was first evaluated using a standardized gut cocktail containing genomic DNA from eight different bacterial species representing different genera of relevance for human health. The method was also tested on DNA that was directly extracted from human faecal samples and it was consistently capable of detecting alterations in the bacterial samples before and after antibiotic treatment. Although the resolution of the method needs improvement, this study represents the first step towards development of a diagnostic LOC for profiling gut bacterial communities.
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