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Showing papers on "Microfluidics published in 1994"


Journal ArticleDOI
TL;DR: Flow dynamics of biological fluids and cell suspensions in straight glass-capped silicon microchannels demonstrated that these microstructures are appropriate components for microfluidic analytical devices, clearly indicating the future role of microStructures for a variety of analytical purposes.
Abstract: Analysis of minute sample volumes is a major analytical challenge that requires an understanding of fluid flow in microstructures. Accordingly, flow dynamics of biological fluids and cell suspensions in straight glass-capped silicon microchannels (40 to 150 microns wide, 20 and 40 microns deep) were studied. We demonstrated that these microstructures are appropriate components for microfluidic analytical devices. Different fluids were easily manipulated in the microchannels, and measurements of flow rate as a function of pressure for whole human blood, serum, plasma, and cell suspensions revealed non-Newtonian behavior. By means of micromachined filters (5 microns) located in channels, blood cells and microparticles were effectively separated from nanoliter-sized samples, clearly indicating the future role of microstructures for a variety of analytical purposes.

246 citations


Journal ArticleDOI
TL;DR: In this paper, a 3D stack concept for the assembly of photolithographically fabricated microfluidic components is presented and discussed, which uses silicon-based micropumps and simple planar structures which mimic standard elements of conventional flow systems.
Abstract: A three-dimensional (3D) stack concept for the assembly of photolithographically fabricated microfluidic components is presented and discussed. The system uses silicon-based micropumps and simple planar structures which mimic standard elements of conventional flow systems. Detection is provided either by solid state electrochemical sensors or small volume optical detection. The general advantages of using micromachined flow manifolds for microchemical analysis are addressed. The particular benefits to be derived from this an approach compared with other assembly methods are also examined.

155 citations


Journal ArticleDOI
TL;DR: In this article, it is envisaged to integrate these micropumps into a module for handling gases and liquids, which can then be coupled with different sensor modules to form microsystems, e.g. for the detection of toxic chemicals in the environment or for bedside analysis in hospitals.
Abstract: The transport of small amounts of fluids and gases must be controlled with a view to automated drug dosage, chemical analysis with microsensors, and hydraulic as well as pneumatic microactuators. Components for microfluidic systems have been developed at Karlsruhe Nuclear Research Center which are manufactured by the LIGA technique. Micropumps have been fabricated by combining thermoplastic molding with membrane techniques. It is envisaged to integrate these micropumps into a module for handling gases and liquids. The module can then be coupled with different sensor modules to form microsystems, e.g. for the detection of toxic chemicals in the environment or for bedside analysis in hospitals. Microvalve systems and fluidic beam amplifiers have been developed for hydraulic and pneumatic actuators. These devices are capable of controlling a liquid or gas stream and may be used to steer e.g. instruments in a catheter tip for minimally invasive surgery.

85 citations