The micromachining technology that emerged in the late 1980s can provide micron-sized sensors and actuators. These micro transducers are able to be integrated with signal conditioning and processing circuitry to form micro-electromechanical-systems (MEMS) that can perform real-time distributed control. This capability opens up a new territory for flow control research. On the other hand, surface effects dominate the fluid flowing through these miniature mechanical devices because of the large surface-to-volume ratio in micron-scale configurations. We need to reexamine the surface forces in the momentum equation. Owing to their smallness, gas flows experience large Knudsen numbers, and therefore boundary conditions need to be modified. Besides being an enabling technology, MEMS also provide many challenges for fundamental flow-science research.

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Micro-electro-mechanical-systems (mems) and fluid flows

The present invention provides novel microfluidic devices and methods that are useful for performing high-throughput screening assays. In particular, the devices and methods of the invention are useful in screening large numbers of different compounds for their effects on a variety of chemical, and preferably, biochemical systems.

High throughput screening assay systems in microscale fluidic devices

A method of fabricating an elastomeric structure, comprising: forming a first elastomeric layer on top of a first micromachined mold, the first micromachined mold having a first raised protrusion which forms a first recess extending along a bottom surface of the first elastomeric layer; forming a second elastomeric layer on top of a second micromachined mold, the second micromachined mold having a second raised protrusion which forms a second recess extending along a bottom surface of the second elastomeric layer; bonding the bottom surface of the second elastomeric layer onto a top surface of the first elastomeric layer such that a control channel forms in the second recess between the first and second elastomeric layers; and positioning the first elastomeric layer on top of a planar substrate such that a flow channel forms in the first recess between the first elastomeric layer and the planar substrate.

Microfabricated elastomeric valve and pump systems

Carbon dioxide is a clean and versatile solvent for the synthesis and processing of a range of materials. This review focuses on recent advances in polymer synthesis and processing using liquid and supercritical CO2. The synthetic techniques discussed include homogeneous solution polymerisation, precipitation polymerisation, dispersion and emulsion polymerisation, and bulk polycondensation. The formation of porous polymers and polymer blends is also considered, and the specific advantages of CO2 in these processes are evaluated in each case. The use of CO2 as a solvent for polymer processing is reviewed from a materials perspective, with particular attention being given to the formation of polymers with well defined morphologies. The variable solvent strength associated with supercritical fluids has been utilised in areas such as polymer fractionation and polymer extraction. Plasticisation phenomena have been exploited for the impregnation and heterogeneous chemical modification of polymeric materials. The formation of microcellular polymer foams by pressure induced phase separation is considered, as is the use of CO2 for polymer particle formation, spray coating, and microlithography. The aim of the review is to highlight the wide range of opportunities available to the materials chemist through the use of carbon dioxide as an alternative solvent.

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Polymer synthesis and processing using supercritical carbon dioxide

A review of polymer dissolution

Methods are provided for the fabrication of polymeric microchannel structures having enclosed microchannels of capillary dimension. The microchannel structures are constructed of a base member (12) and a cover member (14), sealed together. A microchannel structure having walls of a plastic material is formed in a generally planar surface of at least the base member. The cover member has at least one generally planar surface, and the microchannel structure is enclosed by bonding the planar surfaces of the cover member and the base member together. In some embodiments the surfaces of the cover member and base member are both of plastic material, and are directly thermally bonded. In some embodiments a bonding material is applied to one of the surfaces prior to bringing the surfaces together. Suitable bonding material are disclosed.

Methods for fabricating enclosed microchannel structures

Microchannels having at least an acrylic inner surface and methods of their use in electrophoretic applications are provided. The subject microchannels may be in the form of a variety of configurations suitable for holding an electrophoretic medium. The subject microchannels give rise to substantially reduced EOF and/or adsorption as compared to fused silica under conditions of electrophoresis and find use in a variety of electrophoretic applications in which charged entities are moved through a medium under the influence of an applied electric field.

Acrylic microchannels and their use in electrophoretic applications

Methods and apparatus are disclosed for the production of high precision large scale, micro and mini structures (24) using three-dimensional stereolithography. The objects (24) formed using these methods have minimal stress between layers and low curl distortion. The objects also have low warpage because no post-cure treatment is necessary. The methods include the use of elevated pressure, elevated temperature, or sequential polymerization of polymer precursor fluid (10), or a combination of these, in the three-dimensional stereolithographic process.

Rapid prototype three-dimensional stereolithography

The invention provides for modified proppants, comprising a proppant particle and a hydrogel coating, wherein the hydrogel coating localizes on the surface of the proppant particle to produce the modified proppant, methods of manufacturing such proppants and methods of use.

Self-suspending proppants for hydraulic fracturing

Thermooptical analysis (TOA) provides a simple, rapid, and reliable experimental method to determine cloud-point curves of binary polymer/solvent systems. Phase diagrams have been obtained for different molecular weights of polystyrene in cyclohexane, methylacetate, ethylacetate, and tert-butylacetate and for poly(ethylene glycol) in water. Polystyrene solutions exhibit both upper and lower critical solution temperatures, while aqueous poly(ethylen glycol) solutions give closed-loop phase diagrams. The TOA apparatus described here uses very small samples (0.02 cm 3 )

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David S. Soane

Papers

Methods for fabricating enclosed microchannel structures

Acrylic microchannels and their use in electrophoretic applications

Rapid prototype three-dimensional stereolithography

Self-suspending proppants for hydraulic fracturing

Cloud-point curves of polymer solutions from thermooptical measurements