Valve-Less Rectification Pumps

Valve-Less Rectification Pumps, Fig. 1 Schematic representation of a classical large-scale single-action reciprocating pump. The alternating flow, symbolically shown as being generated by a piston and crankshaft... 

Valve-Less Rectification Pumps, Fig. 2 A typical current microfluidic pump - a straightforward adaptation of the principle shown in Fig. 1. The alternating inflow into and outflow from the displacement volume is here typically produced by deformations of an electroactive membrane (diaphragm). The mechanical non-return valves, made by etching, are of the type presented in Figs. 3 and 4... 

Valve-Less Rectification Pumps, Fig. 4 The same valve as in Fig. 3 shown in the CLOSED regime. The membrane presses the excrescence against the bottom of the chamber thus preventing any return flow... 

Valve-Less Rectification Pumps, Fig. 5 Typical valve-less microfluidic single-action pump. The fluid motion, caused by the diaphragm deformations, is rectifled (as explained in Fig. 6) by the Venturi diodes that replace - though not very efficiently - the membrane valves from Figs. 3 and 4... 

Valve-Less Rectification Pumps, Fig. 7 Schematic representation of the double-acting reciprocating pump driven by a full-bridge two-phase actuator. Two alternating flows, mutually phase-shifted by n radians, are rectified by four fluidic diodes coimected to form the Gratz... 

Valve-Less Rectification Pumps, Fig. 8 The term rectifying bridge is based on the underlying idea of the two-phase alternating-flow actuator (alternator) bridging the gap between the two paths that lead from suction to delivery terminals. Note that the simplest case in Kg. 1 is one half of such bridge... 

Valve-Less Rectification Pumps, Fig. 9 Two halfbridges in tandem. Rather than for suppressing the pulsation with the full-wave bridge of Fig. 7, the two driving phases may be used, as shown here, for generating a higher output pressure in series-connected half-bridges... 

Valve-Less Rectification Pumps, Fig. 10 The flow pulsation caused by the absence of driving flow during the suction part of the cycle of the basic pump (Fig. 1) may be reduced (cf. Fig. 7) in the multi-phase pumps. While the version in Fig. 8 works with two phases, an even better smoothing is here achieved with three rectifying halfbridges... 

Valve-Less Rectification Pumps, Fig. 11 Schematic representation lop) and typical properties of the actuators used to generate the alternating fluid flows out from and into the displacement volume... 

Valve-Less Rectification Pumps, Fig. 12 Operating principles with direct electric driving action on the fluid requires a fluid (usually liquid) possessing unusual... 

Valve-Less Rectification Pumps, Fig. 13 Data collected from literature on micropumps show, somewhat surprisingly, that pumps with mechanical valves do not deliver more pumped fluid in the course of each stroke than the pure fluidic ( valve-less ) ones... 

Valve-Less Rectification Pumps, Fig. 14 Published data on micropumps with electrically drivtai moving mechanical component acting (as a pistrai) on the fluid in the displacement cavity. There is a distinct dependence betwetm relative operating fiequtaicy (related to resonance) and Stokes number, which is the similarity parameter of periodic fluid motion... 

Valve-Less Rectification Pumps, Fig. 16 Tesla diode, the earliest no-moving-part device designed to exhibit a large difference between the properties in forward and return flow direction. While the forward flow left, top) is almost straight, the reverse flow right, bottom) enters the complex curved flowpath. Diodity, even in the typical multi-stage layout, is not high, much worse than obtainable with vortex-type fluidic diodes... 

Valve-Less Rectification Pumps, Fig. 18 Planar labyrinth diode - a version more suitable than the one from Fig. 16 for micromanufacturing by photoetching. Despite the clever design the aievable diodity V values are not very high... 

Valve-Less Rectification Pumps, Fig. 19 Jet-type rectifiers. (A) A classical jet-pump generates In the secondary inlet a suction by entrainment into the primary nozzle jet. Due to jet inertia, some effect is retained even during absence of inflow in the passive half-period. 

Valve-Less Rectification Pumps, Fig. 20 Another feature (C) originally introduced by Walkden [6] and later popularised by Tippetts [7] (in the form D with dividing nose) is the two-phase full-wave rectifler with two primary nozzles (actually shaped as diffusers), which alternate in their roles so that the driving action is maintained throughout the cycle... 

Valve-Less Rectification Pumps, Fig. 21 An example of a planar version single-action pump made by one-sided etching in a metal plate. It is driven by alternating air pressure acting on the liquid surface in the displacement cavity. Rectification by convergent-divergent Venturi diodes... 

Valve-Less Rectification Pumps, Fig. 23 The idea from the bottom of Fig. 19 developed into double-action full-wave pump with two three-terminal Venturi rectifiers. Alternating flows are generated by diaphragm deformations perpendicular to the plane... 

Valve-Less Rectification Pumps, Fig. 26 Schematic representation of the jet-type rectifier from Fig. 23, emphasising the underlying idea of full-wave Gratz bridge... 

Valve-Less Rectification Pumps, Fig. 27 Schematic representation of a peristaltic jet-type rectifier with tandem-connected half-bridges (cf. Fig. 9). The... 

Valve-Less Rectification Pumps, Fig. 28 Forward-flow diverting by Coanda-effect attachment to a curved wall. This is the operating principle used in the no-moving-part peristaltic pump [9] or blower [14] for pumping dangerous fluids... 

Valve-Less Rectification Pumps, Fig. 29 The principle of a traveling-wave peristaltic multi-stage pump driven by a two-phase air flow. A considerable proportion... 

Valve-Less Rectification Pumps, Fig. 31 An example of a planar micropump using the principle from Fig. 29. The cavities are made photochemically in a thin plate (above), the driving nozzles are in alternating positions on both sides of the channel. The alternating flow in them is generated by volume variations of an electrostrictive gel in displacement chambers... 

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