Fluidic elements

The simplest approach of splitting one stream into six streams is the use of a fluidic element that directly connects one inlet with six symmetrically arranged outlets [140, 141, 148], Commercial fluid distributors, however, suffer from flow maldistribution, as the smallest deviations in their manufacture have a large impact. Hence specially devices are required for flow splitting to micro devices. A liquid-flow distribution module was one first such device to be realized. 

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. 

Microfluidics is also a cross-disciplinary subject that uses the methods and principles of microelectronics to construct very small analogs or models of such macroscopic fluidic elements as wind tunnels, valves, or fluidic amplifiers. The natural question that comes to mind is at what dimensional scale does fluid motion depart from the extremely well understood and well established laws of fluid dynamics There is no definitive answer to that question yet since the study of fluid motion in microscale and nanoscale structures is still at an early stage. 

Vollmer J, Hein H, Menz W and Walter F 1994 Bistable fluidic elements in LIGA... 

If a Lab-on-a-Chip is defined to be a unit that should be able to perform all chemical functions and detection in a monolithic device that fits in the palm of one s hand (or smaller), then existing Lab-on-a-Chip units are generally still quite underdeveloped. This miniaturization will require increased integration not only of fluidic elements but also of electrical, optical, or other types of elements. The major criteria that lead the choice of a detection scheme are the properties of the analyte (optical, electrical, electrochemical, and physical), the composition of the sample (do the analytes have similar properties and/or similar concentrations ), and the required... 

For those wishing to follow up the numerous techniques for influeucing capillary forces, the paper by Le Berre et al. (2005) on generating electrocapillary forces in nucro-fluidic elements is worthy of study. At the small scale where particles nught be involved in the fluid stream, the impact of electrophoresis and Ihetmophoresis - the... 

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