Microfluidics features

FIGURE 39.1 Schematic illustrations of common microfluidic features utilized in microchip separation devices (a) top view of a multilayer assembly of microchannels formed by capping a layer with etched channels, (b) side view of micropatterned channel with capping flhn layer, (c) side view of a vacnmn-driven three-layer negative pressure valve, (d) side view of a positive pressure valve. 

The mold defines the overall shape of the part, as well as the path by which the molten plastic flows firom the barrel into the mold cavity. In most microfluidic applications, the mold cavity is in the form of a wafer or a die that will contain the microfluidic features on one of its exterior... 

Micromolding (Injection and Compression Molding), Fig. 6 Images taken of (a) commercial electroforming instrument, (b) wafers containing microfluidic features in holders for electroforming instrument, (c) Ni stamp... 

The mass-production of microfluidic devices must be done in a reliable manner. In this study, toolings used to reproduce microfluidic features on cyclic-olefin-copolymer (COC) and polymethyl-methacrylate (PMMA) polymers by amorphous metallic alloy and silicon inserts were compared. Both toolings were used in micro injection molding. Findings indicate that the alloy was mechanically more suitable as mold inserts, whereas silicon had better surface roughness. COC samples showed comparable geometrical replication of microfluidic features compared to PMMA. 

To date, there has been little work done in attempting to use such metallic alloys as the insert in micro injection-molding. It is the aim of this paper to conduct a brief comparison of the geometrical and surface qualities of a set of microfluidic features that will be fabricated onto silicon and metallic glass inserts. Micro injection-molding using the metallic glass insert with COC and PMMA resins will be subsequently performed. The molded samples will also be analyzed. 

A comparison of the microfluidic features, such as surface roughness and geometry, between PMMA and COC samples were made. The metallic glass insert was also re-examined after approximately 120 cycles of use. 

Figure 1. Microfluidic features fabricated onto molding inserts. Labeling denotes areas of interest.

Microfluidic devices, 26 959 effect of scale on, 26 960t fabrication of, 26 963-966 Microfluidics, 26 959-980 applications of, 26 966-975 basic features of, 26 959-966 future directions for, 26 976-977 history of, 26 959 industrial impact of, 26 976 Microfluidic structures fabrication of, 26 963-966 MicroFluidic Systems, 26 976 Micro-gas chromatography (micro-GC), 6 434 37 Microgel particles... 

Several techniques for miniaturization of simple chemical and medical analysis systems are described. Miniaturization of total analysis systems realizes a small sample volume, a fast response and reduction of reagents. These features are useful in chemical and medical analysis. During the last decade many micro flow control devices, as well as the micro chemical sensors fabricated by three dimensional microfabrication technologies based on photofabrication, termed micromachining, have been developed. Miniaturized total analysis systems (pTAS) have been studied and some prototypes developed. In microfabricated systems, microfluidics , which represent the behavior of fluids in small sized channels, are considered and are very important in the design of micro elements used in pTAS. In this chapter microfluidics applied flow devices, micro flow control devices of active and passive microvalves, mechanical and non-mechanical micropumps and micro flow sensors fabricated by micromachining are reviewed. 

The microfluidic system described above has two key features that make it especially amenable to creating such automated reactors firstly, the reaction conditions can be precisely and rapidly manipulated (which in turn means that it is possible to finely tune the physical properties of the reaction product), and secondly, the inline spectrometer provides immediate real-time information about the product. The only remaining element... 

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