Fluidic Pumping

A 14] Micro fluidic pumps with dimensions small enough to be connected inline with the process flow of a micro structured reactor plant are commercially available [78]. The tooth-ring gear pumps of the mzr-series, for example, convey up to 171 h-1 at pressures up to 80 bar. They can be used either as dosing pumps or as booster pumps inline in a hybrid plant or in a micro structured reactor plant with open architecture. The use of the stepwise pressure increase reduces the average plant pressure as indicated schematically in Figure 4.81. 

Fluidic devices need a supply of the fluid with which they operate. Sometimes, there is an available external fluid source, and in other cases, the fluid may be provided from a pressurized vessel. Most often, however, the fluidic circuits are supplied with fluid flow from a fluidic pump. This consists of two essential parts an alternator producing an alternating flow, usually by motion of a reciprocating plunger, piston, or diaphragm, and a rectifier, which changes the alternating flow into a one-way or noiu etum flow. 

In fluidic pumps, the supplied alternating fluid flow is converted into a mostly one-way (and ideally nonreturn) output flow. One possibility to do it is by generating a series of traveling waves in a channel by alternating outflows and suction in a series of nozzles arranged along... 

Fluidic pumps Maintenance-free pumps No-moving-part pumps... 

The term valve-less, despite being common and frequently used, is strictly speaking a misnomer. It is used to describe fluidic pumps... 

Many microfluidic applications use a single central fluidic pump to supply fluid into a number of active devices. Typically, a considerable number of chemical microreactors operating in parallel in combinatorial chemistry tests are usually all supplied by the reactant from a single pump. This means the flow rates requred by the end devices are summed and as a result the Reynolds number of the flow in the central pump is higher than the typical magnitudes elsewhere in microfluidics. This makes the valve-less principles, relying on fluid inertia, quite acceptable. 

Designing a resiprocating fluidic pump necessitates decisions made about three basic factors ... 

Fluidic pumping offers a wide field for potential improvements. Efficiency which, until now, has been of secondary importance, less important than manufacturing simplicity and maintenance-free operation, may become an obvious target for optimization. Besides development of new rectification principles with better diodity properties. 

Design a fluidic pump in a multiproject wafer process. The pump should have a volumetric flow rate of 20 nL/s for water through a 100 pm X 100 pm microchannel that is 1 mm long. What pressure difference is required to achieve this flow rate Before starting, perform a literature search to see what has been done in the past. 

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