Fluid handling – Systems – With flow control means for branched passages
Reexamination Certificate
2002-03-06
2004-06-01
Fox, John (Department: 3753)
Fluid handling
Systems
With flow control means for branched passages
Reexamination Certificate
active
06742544
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention generally relates to a novel fluid control valve, more particularly an injection valve comprising a plurality of microvalves for injecting discrete charges of gas into a mobile phase or carrier stream, which is particularly useful in high resolution gas chromatography. Further, the present invention provides for parallel arrays of gas injection valves in which multiple samples may be injected into multiple carrier streams substantially simultaneously.
The parallel injection valves of the present invention can be advantageously incorporated into parallel detection systems, including especially parallel gas chromatographs. In a preferred application, the parallel injection valves can be used in conjunction with a multi-channel gas chromatograph as disclosed in U.S. Ser. No. 09/801,430, entitled “Parallel Gas Chromatograph with Microdetector Array” filed Mar. 7, 2001 by Srinivasan et al.
Such parallel detection systems are of substantial importance for high-throughput combinatorial catalysis research programs, wherein chemical reactions are conducted simultaneously using small volumes of reaction materials to efficiently and economically screen large libraries of chemical materials. Preferred parallel screening reactors include the parallel flow reactors as disclosed in U.S. Pat. No. 6,149,882 to Guan et al., U.S. Ser. No. 09/518,794 filed Mar. 3, 2000 by Bergh et al., U.S. Ser. No. 60/185,566 filed Mar. 7, 2000 by Bergh et al., U.S. Ser. No. 60/229,984 filed Sep. 2, 2000 by Bergh et al., U.S. Ser. No. 09/801,390, entitled “Parallel Flow Process Optimization Reactor” filed Mar. 7, 2001 by Bergh et al., U.S. Ser. No. 09/801,389, entitled “Parallel Flow Reactor Having Variable Feed Composition” filed Mar. 7, 2001 by Bergh et al., and U.S. Ser. No. 60/274,065, entitled “Parallel Flow Reactor Having Improved Thermal Control” filed on Mar. 7, 2001 by Bergh et al. These reactors can effect reactions in tens, hundreds or even thousands of channels simultaneously or substantially concurrently.
In more advanced online gas monitoring applications such as the high-throughput combinatorial catalysis research programs described above, it is possible to produce sample streams of fluid at various pressures. Most often the samples are at a different pressure than the carrier stream of the gas chromatograph. Injecting samples into a carrier stream at a different pressure is undesirable as pressure gradients can cause sample dispersion, which results in unwanted band broadening that may detrimentally affect the quality of the analysis of the sample. Moreover, pressure difference between samples makes the sample sizes different. Thus, it is important to be able to depressurize the sample after collection, and before injection or transfer to an analysis system, to minimize band broadening and to ensure accurate, reliable analysis.
WO 00/23734 discloses a gas chromatography apparatus comprising a multi-valve assembly including a series of microvalves for sample injection. The multi-valve assembly comprises a series of plates and diaphragms wherein fluid flow is controlled by two pistons. A pressurized actuation gas operates to alternately elevate one or the other of the pistons, which acts to either open or close an individual microvalve. The disclosed multi-valve assembly incorporates six individual microvalves which operate in combination in the same way as a standard 6-port rotary injection valve known in the art of fluid control. Thus, the microvalves of the reference do not provide for sample depressurization prior to sample injection. Further, the rotary arrangement of the disclosed multi-valve assembly limits the size of the valve apparatus such that it is not compatible with or readily capable of being incorporated in a large, parallel chromatography array.
Unlike the prior art, the present invention discloses a gas injection valve comprising a plurality of novel microvalves that can be arranged in valving schemes relevant to online gas analysis applications, for example, allowing a discrete sample of a gas to be depressurized prior to transfer or injection into an analysis apparatus or reaction system.
SUMMARY OF THE INVENTION
Among the several objects and features of the present invention may be noted the provision of a gas injection valve comprising one or more microvalves; the provision of such an injection valve wherein each microvalve is capable of being independently actuated; the provision of such an injection valve that may be micro-fabricated; the provision of such an injection valve capable of receiving gas at different pressures and emitting discrete charges of gas at approximately the same pressure; and the provision of such an injection valve which may be incorporated into a parallel array of injection valves for handling multiple gas samples substantially simultaneously.
Briefly, therefore, apparatus of the invention is a microvalve assembly for use in receiving gas at different pressures and emitting discrete charges of gas at approximately the same pressure. The microvalve assembly comprises a valve body having a gas inlet passage adapted for connection to a line for receiving gas at different pressures, a gas outlet passage, a gas charge loop and a pressure control port. The microvalve assembly further comprises (1) a first microvalve associated with the valve body adapted to admit gas passing into the gas inlet passage into the gas charge loop in a first position of the valve and to block entry of gas from the gas inlet passage into the gas charge loop in a second position; (2) a second microvalve associated with the valve body adapted to open the gas charge loop to the pressure control port for reducing the pressure of gas in the gas charge loop in a first position and to block the gas charge loop from the pressure control port in a second position; and, (3) a third microvalve associated with the valve body adapted to open the gas charge loop to the gas outlet passage for emitting the discrete charge of gas from the gas loop from the valve body in a first position and to block the gas charge loop from the gas outlet passage in a second position.
Further, apparatus of the invention include an injection valve array capable of controlling fluid flow from multiple sources substantially simultaneously. The injection valve array comprises multiple injection valves arranged generally adjacent in a linear or curvilinear array. Each injection valve comprises at least one microvalve including (1) a first plate having inlet passages, outlet passages, and fluid transfer channels in a first face, the fluid transfer channels extending between respective pairs of inlet passages and outlet passages to permit fluid communication between the pairs of inlet and outlet passages of said first plate extending between the inlet and outlet passages for fluid communication therebetween; (2) a second plate in generally opposed relation with the first face of the first plate and having piston receptacles toward the first face of the first plate; (3) a sealing membrane located between the first face of the first plate and the second plate; and, (4) a piston for each of said piston receptacles of the second plate, each piston being at least partially disposed in the piston receptacle and movable relative to the first plate between an open position in which the sealing membrane does not block fluid flow in a corresponding one of the fluid transfer channels between the inlet passage and outlet passage, and a closed position in which the piston deforms the sealing membrane to block fluid flow in said corresponding one of the fluid transfer channels between the inlet passage and outlet passage.
Further, apparatus of the invention include a gas injection valve for use in injecting gas samples at controlled pressure into a gas chromatograph. The gas injection valve comprises a gas sample inlet port; a carrier gas inlet port; a gas sample loop; a waste port; a pressure control port; an outlet port; passaging extending between the gas sample inlet port, the c
Bergh H. Sam
Doffing Frank
Klaus Michael
Pinkas Daniel M.
Schoenfeld Friedhelm
Fox John
Senniger Powers Leavitt & Roedel
Symyx Technologies Inc.
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