Microfluidic Rotary Pump

Precise control of the fluid flow inside microchannels is an important issue for the development of the microfluidics technology. Microfluidic rotary pumps with different configurations serve as subtle solutions to control the flow in microfluidic devices, and will contribute to the development of the microfluidics technology. 

Microfluidic Rotary Pump, Figure 1 Schematic drawing of microfluidic rotary pump. Eccentricity, s = yc/ H - R). e = 0 means the cylinder is at the center, s = 1 means the cylinder touches the bottom wall... 

The mixing ability of microfluidic systems was tested using a rotary pump, a circular channel with inputs and outputs that can be peristaltically pumped, opeued, and closed. It was found that after only a few minutes of active mixing (due to pumping), a uniform mixture of particles is obtained that would have taken hours to achieve by diffusion. This is also useful for accelerating diffusion-... 

Mkrofluidk Rotary Pump, Fig. 4 Schematic drawing of a microfluidic viscous rotary pump... 

MEMS find wide applications in microsensors such as acoustic waves, biomedical, chemical, inertia, optical, pressure, radiation, and thermal microactuators like valves, pumps, and microfluidics electrical and optical relays and switches grippers tweezers and tongs as well as linear and rotary motors, etc., in various fields. They also find application in microdevice components such as palmtop reconnaissance aircrafts, minirobots and toys, microsurgical and mobile telecom equipment, read/ write heads in computer storage systems, as well as ink-jet printer heads [4]. 

ConventiOTial centrifugal or axial turbomachinery are not suitable for micro and nanoscales where Reymolds numbers are generally small, centrifugal and inertial forces are negligible, and viscous forces dominate the flow field (an excellent review can be found on the physics of microscale fluid flow in [1]). Many different types of micropumps have been proposed, developed and commercialized for microfluidics appfications. Rotary micropumps make use of mechanical micro rotors to pump the fluid. Due to the dominance of viscous forces in micro scale, carrying out the pumping action by means of viscous forces is possible. A group of rotary micropumps operate on this concept [2, 3]. The other branch of rotary micropumps resembles its macro counterparts in the sense that it makes use of pressure forces to drive the fluid [4—14]. 

One of the earliest types of rotary micropumps developed for microfluidics applications, drug delivery in particular, is the jet-type magnetically driven fluid micropump. It is based on a rotary micromotor which is attached to a toothed rotor (Fig. 1). Basically, it is a micro version of conventional positive displacement pump. Flow rates up to 24 pL/min at a pressure of 10 kPa have been obtained using this design [4]. 

The individual actuators in a peristaltic pump can also serve as individual valves. Additional flexibility in integrating peristaltic pumps into large microfluidic systems can be gained from providing components with multiple functions. An example of this is the rotary mixer described in Ref. [12], which can serve as an effective dynamic micromixer or as a peristaltic pump, depending on the actuation pattern of the individual valves. 

Quake and coworkers [16] developed a PDMS microfluidic device (shown in Fig. 4c) for nucleic acid purification from a small number of bacterial or mammalian cells. This multilayer device contained fluidic channels and a system of membrane-actuated pneumatic valves and pumps, which enabled precise control of buffers, lysis agents, and cell solution and also allowed for parallel processing. Bacterial cells, dilution buffer, and lysis buffer are first introduced into the chip and then transferred into the rotary mixer. Once mixed, the lysate is flushed over a DNA affinity column and drained. The DNA... 

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