Microfabricated fluidic devices device

Microfabricated fluidic devices (microchips) are potentially useful for multidimensional separations because high-efficiency separations can be achieved and small sample volumes can be manipulated with minimal dead volumes between interconnecting channels. Electro-kinetically driven separation techniques demonstrated on microchips include... 

Rocklin, R. D., Ramsey, R. S., and Ramsey, J. M. (2000). A microfabricated fluidic device for performing two-dimensional liquid-phase separations. Anal. Chem. 72, 5244-5249. 

FIGURE 7.41 Picture of the microfabricated fluidic device integrated with a standard MALDI-TOF sample plate. Because of the self-activating character of the microfluidic device, the system can be introduced into the MALDI ionization chamber without any wire or tube for the sample introduction and the flow control [820]. Reprinted with permission from the American Chemical Society. 

Culbertson, C.T., Alarie, J.P., McClain, M.A., Jacobson, S.C., Ramsery, J.M., Rapid cellular assays on microfabricated fluidic device. Micro Total Analysis Systems, Proceedings 5th [iTAS Symposium, Monterey, CA, Oct. 21-25, 2001, 285-286. 

The Coupling of Microfabricated Fluidic Devices with Electrospray Ionization Mass Spectrometers... 

Interfacing Microfabricated Fluidic Devices to the Outside World... 

These techniques represented our full attempts at connecting microfabricated fluidic devices to the outside world. We had pushed as far as we could with our limited engineering resources in order to develop the interface. At that point, it was time for industries to also get into the game of coupling microfabricated devices to mass spectrometers. 

Rocklin RD et al (2000) A microfabricated fluidic device for performing two-dimensional liquid-phase separations. Anal Chem... 

Many individually microfabricated fluidic devices have been demonstrated and even marketed commercially. As sample volumes become smaller, and the analysis of individual cells or molecules is desired, the research instra-mentation itself decreases in size and new methods of interconnection and assembly are required. Microfluidic corrponents must often first be assembled from smaller subunits (e. g., channels, actuators) and then further assembled together to form microfluidic systems and instrumen-... 

For some years now microreactors [1, 2] have been attracting the interest of the scientific community. Since microfabrication technology made microstructured fluidic devices available they have been studied for their scope and limitations. There have also been attempts to introduce such systems into the industrial... 

The deep reactive ion etching (DRIE) technique, first presented in the mid- to late 1990s, facilitated the fabrication of numerous innovative microsystems, especially power-MEMS systems. Since most MEMS devices involve some form of lithography-based microfabrication, the use of flat substrates is required. Often, these flat substrates involve the use of DRIE methods and result in structures characterized by extrusion of two-dimensional features into the third dimension as illustrated in Fig. 2. Therefore, microfluidic components are often limited in their geometrical appearance, which precludes full three-dimensional shapes commonly found in many large-scale fluidic devices such as pumps hydrofoils, turbine blades and vanes, mixers, etc. 

Behavior of the fluids in the microfabricated channels are different from those in the millimeter scale channels. Miniaturization of micro flow devices opens a new research field, microfluidics which represents the behavior of the fluid in the micro channel [8]. Since the Reynolds number in the micro channel is usually below 200, the flow is laminar and special design concepts are necessary for the fluidic elements of mixers, reaction coils etc. in the pTAS. Some components of flow switches and fluid filters were developed using laminar flow behavior. 

An integrated microfabricated cell sorter has been constructed using a control layer and a fluidic layer fabricated on PDMS [890]. The control layer consists of valves that will be pneumatically controlled by pressurized N2. This device is superior to an electrokinetic sorter, which suffers from buffer incompatibilities and frequent voltage adjustments because of ion depletion or pressure imbalance due to evaporation. E. coli cells expressing EGFP were sorted and selected out from a cell mixture which also contained E. coli cells expressing the / -nitrobenzyl (PNB) esterase. About 480,000 cells have been sorted at a rate of 44 cefls/s in 3 h. The recovery yield was 40% and the enrichment ratio was about 83-fold [890]. 

The ability to fill a device with many different fluids in different channels and chambers allows for the implementation of a simple and robust geometric method of metering solutions. The principle behind this scheme is to set up a geometry in which two microfluidic chambers may be primed with different solutions and connected via a fluidic interface that is controlled by a microfabricated valve (Fig. 11.4). With a central interface valve closed, the two chambers are first deadend filled with two different solutions using the POP technique. Once both chambers have been completely filled, containment valves are actuated, isolating the chambers from the rest of the chip. The interface valve is then opened, creating a... 

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