Chemistry: electrical and wave energy – Processes and products – Electrophoresis or electro-osmosis processes and electrolyte...
Reexamination Certificate
1999-08-13
2001-05-01
Phasge, Arun S. (Department: 1741)
Chemistry: electrical and wave energy
Processes and products
Electrophoresis or electro-osmosis processes and electrolyte...
C204S600000, C204S647000, C204S648000, C417S052000
Reexamination Certificate
active
06224728
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention pertains generally to valves for controlling fluid flow and particularly to microvalves that use electrokinetic pump actuation for fluid flow control in microfluidic systems.
Recent advances in device miniaturization have led to the development of microfluidic devices that are designed, in part, to perform a multitude of chemical and physical process. Typical applications include analytical and medical instrumentation, and industrial process control equipment. Microvalves are an important component of the microfluidic systems used in these applications.
Although there are numerous micro-fabricated valve designs that use a wide variety of actuation mechanisms, only two of these designs are incorporated in commercially available microvalves, with thermopneumatic expansion being used as the actuation mechanism in one design and a shape memory alloy diaphragm and bias spring in the other. However, these microvalves suffer from the fact that they consume relatively large amounts of power during operation, typically between 200 and 1500 mW depending upon the design. This high power consumption can be a significant disadvantage if power must be supplied by batteries or the microvalve is placed on a microchip. Moreover, valves using the aforementioned actuation mechanisms can only generate modest actuation pressures.
What is needed is a microvalve that can be used for microfluidic systems that requires significantly less power to operate, can exert larger actuation pressures than can be presently developed by conventional microvalves, is suitable for use on a microchip, and provides both rapid “on” and “off” actuation.
SUMMARY OF THE INVENTION
The present invention is directed to a valve that can generate actuation pressures in excess of 8000 psi and can be used for controlling fluid flow, both gas and liquid, particularly in microfluidic systems. These novel microvalves can be operated, generally, at a power of less than about 10 mW, and particularly at a power of less than about 1 mW.
In contrast to prior art microvalves, the present valve employs an electrokinetic pump to generate the pressure required to operate, or actuate, the valve itself. The use of an electrokinetic pump to operate the microvalve provides several significant advantages over conventional microvalves. Among these is the ability to incorporate the actuation device and valve into a unitary structure that can be placed onto a microchip, the ability to generate higher actuation pressures and thus control higher fluid pressures than conventional actuation means, and the requirements for only microwatts of power for activation. Further, by employing the hydraulic pressure developed by an electrokinetic pump to operate the microvalve, it is now possible to contemplate radically different microvalve designs.
REFERENCES:
patent: 5375979 (1994-12-01), Trah
patent: 6019882 (2000-02-01), Paul et al.
Frye-Mason Gregory C.
Hencken Kenneth R.
Manginell Ronald P.
Oborny Michael C.
Paul Phillip H.
Nissen Donald A.
Phasge Arun S,.
Sandia Corporation
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