المؤلفون: Banerjee, Indradumna, Salih, Tagrid, Ramachandraiah, Harisha, Erlandsson, Johan, Pettersson, Torbjörn, Araújo, A. C., Karlsson, M., Russom, Aman, Assoc.Prof.

المصدر: RSC Advances. 7(56):35048-35054

مصطلحات موضوعية: Chemical analysis, Chemical detection, Clocks, Colorimetric analysis, Colorimetry, Coefficient of determination, Colorimetric detection, Lactate dehydrogenase, Micro-chambers, Point of care, Point of care diagnostic, Red channels, Sample preparation, Microfluidics

الوصف: We report a microfluidic sample preparation platform called "Slipdisc" based on slipchip technology. Slipdisc is a rotational slipchip that uses a unique hand-wound clockwork mechanism for precise movement of specially fabricated polycarbonate discs. In operation, the microchannels and microchambers carved on the closely aligned microfluidic discs convert from continuous filled paths to defined compartments using the slip movement. The clockwork mechanism introduced here is characterised by a food dye experiment and a conventional HRP TMB reaction before measuring lactate dehydrogenase (LDH) enzyme levels, which is a crucial biomarker for neonatal diagnostics. The colorimetry based detection of LDH was performed with an unmodified camera and an image analysis procedure based on normalising images and observing changes in red channel intensity. The analysis showed a close to unity coefficient of determination (R2 = 0.96) in detecting the LDH concentration when compared with a standard Chemical Analyser, demonstrating the excellent performance of the slipdisc platform with colorimetric detection. The versatile point of care sample preparation platform should ideally be suited for a multitude of applications at resource-limited settings.

وصف الملف: print

الوصول الحر: https://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-219077Test
https://doi.org/10.1039/c7ra05209jTest

مصطلحات موضوعية: atmospheric scanning, electron beam processing, abiogenesis, electron microscopy, artificial atmospheres, gas micro-chambers

الوصف: В данном обзоре рассматриваются возможности использования электронной микроскопии в газовых средах для анализа и морфофизиологического воздействия на биологические структуры. Исследуются подходы, в рамках которых изменяется не только состав газовой атмосферы, но и температура, влажность, давление/разрежение. Указывается на применимость кинетического/динамического подхода для манипуляций на тканях и биокосных структурах. Как частный случай воздействия на среду в искусственных атмосферах отмечается возможность моделирования индуцируемого пучком формирования и дезинтеграции молекулярных структур абиогенетического характера. This paper reviews opportunities of using electron microscopy in various gas atmospheres for the analysis and morpho-physiological modification of biological structures. The approaches that allow varying the gaseous phase content, as well as temperature, humidity and pressure are considered. The applicability of both kinetic and dynamic approaches to the tissue and bioinorganic structure manipulations is pointed out. A possibility of simulation of the beam-induced formation and disintegration of abiogenetic molecular structures is also mentioned as a particular case of the electron beam influence and treatment of the precursor medium in an artificial atmosphere.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::89ce58671e6ed9a3281c550676ab0a73Test

المؤلفون: Glover, Katherine, Strang, Jon, Lubansky, Alex

المصدر: Research outputs 2014 to 2021

مصطلحات موضوعية: Concentration field, Mass transfer, Microfluidics, Quiescent environment, Geometry, Biofilm development, Concentration fields, Concentration gradients, Concentration profiles, Diffusion chamber, Equilibrium time, Micro-chambers, Quiescent environments, Chemical Engineering

الوصف: A microfluidic diffusion chamber with 3 inlets and a circular central chamber allows a 2D concentration gradient to develop. This diffusion chamber has been characterised numerically for the effect geometry has on equilibrium time, the concentration profile and the flow profile within the central chamber. As the Einstein-Smoluchowski relation predicts, the time to reach steady state is proportional to the square of the radius of the chamber but features within the chamber are qualitatively insensitive to the size of the chamber within the range of 100-1000. μm. Inlet width had a much more significant effect on the qualitative behaviour within the chamber, affecting the symmetry of the concentration profile. It is recommended that inlet widths are less than 80. μm to preserve symmetry. In this paper, the effect of geometry on both transient and steady-state behaviour has been explored, providing a basis and criteria for designing chambers for a wide range of applications, including studying the effect of concentration gradients on cell mobility or a rapid assay for biofilm development in a range of concentrations.

العلاقة: https://ro.ecu.edu.au/ecuworkspost2013/87Test; http://dx.doi.org/10.1016/j.ces.2014.06.045Test

الإتاحة: https://doi.org/10.1016/j.ces.2014.06.045Test
https://ro.ecu.edu.au/ecuworkspost2013/87Test

المؤلفون: Clime, L., Brassard, D., Pezacki, J.P., Veres, T.

مصطلحات موضوعية: 3-D microfluidic, Air bubbles, Autonomous systems, Biological fluids, Capillary rise, Complete wetting, Complex 3D geometry, Contact line dynamics, Critical parameter, Geometrical optimization, Lattice Boltzmann method, Liquid gas interface, Liquid solids, Liquid water, Micro fluidic system, Micro-chambers, Micro-fluidic devices, Microfluidic cavity, Microfluidic channel, Numerical approaches, Numerical models, Numerical results, Parallel implementations, Performance criterion, Physical process, Quantitative effects, Rectangular cavity, Self-priming, Target regions, Capillary flow

الوصف: We present a numerical approach to the capillary rise dynamics in microfluidic channels of complex 3D geometries. In order to optimize the delivery of specific biological fluids to target regions in microfluidic capillary autonomous systems (CAS), we analyze self-priming of liquid water into a microfluidic device consisting of a microfluidic channel that feeds a rectangular microfluidic cavity trough an appropriately designed micro-chamber. The target performance criteria in our optimization are (1) fast and complete wetting of the cavity bottom while (2) minimizing the probability of trapping air bubble in the device. The numerical model is based on the lattice Boltzmann method (LBM) and a three-dimensional single-component multiple-phase (SCMP) scheme. By using a parallel implementation of this algorithm, we investigate the physical processes related to the invasion of the liquid-gas interfaces in rectangular cavities at different liquid-solid contact angle and shapes of the transition micro-chamber. The numerical results has successfully captured important qualitative and some key quantitative effects of the liquid-solid contact angle, the roughness of the cavity edges, the depth of the holes and shape of the micro-chambers. Moreover, we present and validate experimentally simple geometrical optimizations of the microfluidic device that ensure the complete filling the microfluidic cavity with liquid. Critical parameters related to the overall priming time of the device are presented as well. © 2011 Crown Copyright as represented by the National Research Council. ; Peer reviewed: Yes ; NRC publication: Yes

وصف الملف: text

العلاقة: Microfluidics and Nanofluidics, Volume: 12, Issue: 1-Apr, Publication date: 2012, Pages: 371–382

الإتاحة: https://doi.org/10.1007/s10404-011-0881-7Test
https://nrc-publications.canada.ca/eng/view/object/?id=5bc506ac-d294-43f8-973d-b8c60af3a295Test
https://nrc-publications.canada.ca/fra/voir/objet/?id=5bc506ac-d294-43f8-973d-b8c60af3a295Test

المؤلفون: Pavin, Nenad, Laan, Liedewij, Ma, Rui, Dogterom, Marileen, Jülicher, Frank

مصطلحات موضوعية: In-vitro, Living cell, Micro-chambers, Microtubule organizing centers, Microtubules, Positioning process, Pulling force, Pushing forces, Theoretical result

الوصف: Positioning of microtubule (MT) organizing centers with respect to the confining geometry of cells depends on pushing and/or pulling forces generated by MTs that interact with the cell cortex (Dogterom et al 2005 Curr. Opin. Cell Biol. 17 67–74). How, in living cells, these forces lead to proper positioning is still largely an open question. Recently, it was shown by in vitro experiments using artificial microchambers that in a square geometry, MT asters center more reliably by a combination of pulling and pushing forces than by pushing forces alone (Laan et al 2012a Cell 148 502–14). These findings were explained by a physical description of aster mechanics that includes slipping of pushing MT ends along chamber boundaries. In this paper, we extend that theoretical work by studying the influence of the shape of the confining geometry on the positioning process. We find that pushing and pulling forces can have centering or off-centering behavior in different geometries. Pushing forces center in a one- dimensional and a square geometry, but lead to off-centering in a circle if slipping is sufficiently pronounced. Pulling forces, however, do not center in a one-dimensional geometry, but improve centering in a circle and a square. In an elongated stadium geometry, positioning along the short axis depends mainly on pulling forces, while positioning along the long axis depends mainly on pushing forces. Our theoretical results suggest that different positioning strategies could be used by different cell types.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=57a035e5b1ae::5164646c9781b78cf1c40964a725b631Test
https://doi.org/10.1088/1367-2630/14/10/105025Test

مستخلص: We report a microfluidic sample preparation platform called "Slipdisc" based on slipchip technology. Slipdisc is a rotational slipchip that uses a unique hand-wound clockwork mechanism for precise movement of specially fabricated polycarbonate discs. In operation, the microchannels and microchambers carved on the closely aligned microfluidic discs convert from continuous filled paths to defined compartments using the slip movement. The clockwork mechanism introduced here is characterised by a food dye experiment and a conventional HRP TMB reaction before measuring lactate dehydrogenase (LDH) enzyme levels, which is a crucial biomarker for neonatal diagnostics. The colorimetry based detection of LDH was performed with an unmodified camera and an image analysis procedure based on normalising images and observing changes in red channel intensity. The analysis showed a close to unity coefficient of determination (R2 = 0.96) in detecting the LDH concentration when compared with a standard Chemical Analyser, demonstrating the excellent performance of the slipdisc platform with colorimetric detection. The versatile point of care sample preparation platform should ideally be suited for a multitude of applications at resource-limited settings.
QC 20171201

مصطلحات الفهرس: Chemical analysis, Chemical detection, Clocks, Colorimetric analysis, Colorimetry, Coefficient of determination, Colorimetric detection, Lactate dehydrogenase, Micro-chambers, Point of care, Point of care diagnostic, Red channels, Sample preparation, Microfluidics, Analytical Chemistry, Analytisk kemi, Article in journal, info:eu-repo/semantics/article, text

URL: http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-219077Test
RSC Advances, 2017, 7:56, s. 35048-35054

مستخلص: Glover K., Strang J., Lubansky A. (2014). Characterising the effect of geometry on a microchamber for producing controlled concentration gradients. Chemical Engineering Science, 117(), 389-395. Available here

مصطلحات الفهرس: Concentration field, Mass transfer, Microfluidics, Quiescent environment, Geometry, Biofilm development, Concentration fields, Concentration gradients, Concentration profiles, Diffusion chamber, Equilibrium time, Micro-chambers, Quiescent environments, Chemical Engineering, Journal Article

URL: https://ro.ecu.edu.au/ecuworkspost2013/87Test