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No description available.

No description available.

During the last decade, large and costly instruments are being replaced by system based on microfluidic devices. Microfluidic devices hold the promise of combining a small analytical laboratory onto a chip-sized substrate to identify, immobilize, separate, and purify cells, bio-molecules, toxins, and other chemical and biological materials. Compared to conventional instruments, microfluidic devices would perform these tasks faster with higher sensitivity and efficiency, and greater affordability. Dielectrophoresis is one of the enabling technologies for these devices. It exploits the differences in particle dielectric properties to allow manipulation and characterization of particles suspended in a fluidic medium. Particles can be trapped or moved between regions of high or low electric fields due to the polarization effects in non-uniform electric fields. By varying the applied electric field frequency, the magnitude and direction of the dielectrophoretic force on the particle can be controlled. Dielectrophoresis has been successfully demonstrated in the separation, transportation, trapping, and sorting of various biological particles. / Singapore-MIT Alliance (SMA)

A computational fluid dynamics model has been developed to study an oil-coated particle immersed in a uniform aqueous flow, to determine the conditions that favour oil separation. The governing flow equations are discretized using a finite volume approach, and the oil/water interface is captured using the Volume-of-Fluid (VOF) method in a 2D spherical coordinate system. The model predicts different mechanisms for oil separation. At a Reynolds number, Re, equal to 1, and at a low capillary number, Ca << 1, the high interfacial tension can induce rapid contact line motion, to the extent that the oil film can advance past its equilibrium position and separate from the particle. This mechanism requires that the contact angle measured through the oil phase is large. On the other hand, as Ca approaches 1, the shear exerted by the external flow stretches the oil into a thread that will eventually rupture and separate.

A computational fluid dynamics model has been developed to study an oil-coated particle immersed in a uniform aqueous flow, to determine the conditions that favour oil separation. The governing flow equations are discretized using a finite volume approach, and the oil/water interface is captured using the Volume-of-Fluid (VOF) method in a 2D spherical coordinate system. The model predicts different mechanisms for oil separation. At a Reynolds number, Re, equal to 1, and at a low capillary number, Ca << 1, the high interfacial tension can induce rapid contact line motion, to the extent that the oil film can advance past its equilibrium position and separate from the particle. This mechanism requires that the contact angle measured through the oil phase is large. On the other hand, as Ca approaches 1, the shear exerted by the external flow stretches the oil into a thread that will eventually rupture and separate.

No description available.

This work aims to investigate if it is realistic to use acoustic particle separation techniques for separating heavy-metals from pump-dredged seabed sediments on a large scale. A premise for the project has been that the material should undergo hydrothermal carbonization (HTC) before acoustic treatment. A number of scientific articles have been studied to understand where the frontier is regarding manipulating small particles in fluids using high frequency sound (ultrasound). Discussion has been held with experts on ultrasound, HTC and chemical analyses. In Conclusion, the feasibility of removal of heavy-metals from HTC-treated material using ultrasound have been evaluated based on theoretical possibilities, comparisons to a selection of similar studies, and on some measured properties of the material. Prerequisites for practical experiments, that would prove or disprove this feasibility, have been explored. The possibility to scale up the process has been discussed. / Detta arbete söker svar på om det är realistiskt att använda akustiska metoder för att i stor skala sortera ut tungmetaller från pump-muddrat sjöbottensediment. Utgångspunkten har varit att materialet ska genomgå hydrotermisk karbonisering (HTC) innan akustisk behandling. Ett antal vetenskapliga rapporter har studerats för att kunna förstå var forskningsfronten är, gällande att manipulera små partiklar i vätska med hjälp av högfrekvent ljud (ultraljud). Diskussion har hållits med experter på ultraljud, HTC och kemisk analys.  Avslutningsvis har möjligheten att avlägsna tungmetaller ifrån HTC-behandlat material med hjälp av ultraljud evaluerats, baserat på teoretiska möjligheter, jämförelser med ett urval av liknande studier, och begränsade mätningar av egenskaper hos materialet. Förutsättningarna för praktiska experiment, som skulle kunna bevisa eller motbevisa denna möjlighet, har utforskats. Möjligheten att skala upp processen har diskuterats.

The ability to control the motion of particles and cells in microchannels has been a center of fascination since the advent of microfluidics. Entire fields have been created in order to accomplish separation, volume reduction and overall positioning of particles and cells within microfluidic devices in the fastest and most accurate manner possible. While most of these technologies rely on low Reynolds number operation, one technique entitled inertial focusing takes advantage of the inertia of the surrounding fluid and the interaction between a particle and the channel itself which cause the lateral migration of particles across streamlines to equilibrium positions within a flow. The major advantage of inertial microfluidics in biomedical and microfluidic applications is that it is inherently high throughput being dependent on inertia whereas most microfluidic concepts are dependent on low Reynolds number operation. / Engineering and Applied Sciences

Clean water is hard to obtain in certain areas, such as remote locations and during emergency response. Our study developed a membraneless water purification system using diffusiophoresis and tested the influence of various factors (gas pressure, liquid flow rate, etc.) on the turbidity of filtered water. The main component in the separation system is a tube-in-tube-in-tube separator. The inner tube and the middle tube are made of a semipermeable material (Teflon AF-2400), which allows gas (CO2) to permeate through it, but retains liquid (water). In this strategy, the CO2 permeates through the inner tube (the end is sealed) then dissolves into the dirty water/particle suspension passing through the middle tube. It then diffuses radially to the outer tube, where a vacuum collects the CO2, forming a concentration gradient of ions through the water, which induces the migration of charged particles to concentrate at the inner wall of the middle tube. The vacuum phase in the outer tube can increase the concentration gradient of ions in the water and recycle the CO2. Finally, purified water can be collected from the center of the middle tube by a needle in the effluent. The purification system is able to take initial turbid water (243 NTU) to below the WHO drinking water standard (