Chemical apparatus and process disinfecting – deodorizing – preser – Control element responsive to a sensed operating condition
Reexamination Certificate
1997-09-11
2001-02-20
Stinson, Frankie L. (Department: 1742)
Chemical apparatus and process disinfecting, deodorizing, preser
Control element responsive to a sensed operating condition
C073S863730, C137S625170
Reexamination Certificate
active
06190616
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to capillary valves and devices for interconnecting capillary tubes with each other, with microfabricated devices, and macroscale devices.
BACKGROUND OF THE INVENTION
Capillary tubes are useful in a wide range of microfluidic applications, particularly where volumes on the order of a microliter or smaller are handled. Capillaries are made of glass, metal, silica, or a polymer. The outer diameter of a capillary tube ranges from under 100 to over 750 microns. The diameter of the inner bore ranges from 2 to over 500 microns. With only minimal amounts of chemicals required, systems utilizing capillary tubes are well suited for producing high sample throughput with minimal use of space and materials. In electrophoretic applications, the high surface to volume ratio of capillaries enables the use of high voltages with low joule heating. The use with high voltages results in the ability to electrophoretically separate compounds in capillary tubes at several times the speed and resolution available with traditional slab electrophoretic separation.
Numerous applications have developed to take advantage of the benefits that capillary tubes provide. For example, one use of capillary tubes is in microfluidic devices where capillary tubes are used to transport small amounts of fluid from one location to another. Another application using capillary tubes entails temporarily sealing both ends of a capillary tube to form a nanoscale reaction vessel. Finally, chromatographic devices utilize capillary tubes to provide a separation column for substances. The substances can then be separated based on their physical properties, such as mass, size, or shape. Such applications include gas chromatography and liquid microbore chromatography.
All of these applications require that sections of capillaries be connected to each other. For example, gas chromatography will require an injection port that can introduce a sample into a flow stream. The varied uses of capillary tubes require capillary connectors that are both versatile and resilient. The physical stresses placed on these capillary connectors are most demanding. The connector must be inert to reactive substances that flow through the capillaries, including organic solvents. The connector must remain leak free when used to contain a liquid, gas, or a fluid separation matrix at pressures ranging from 0 to 10,000 PSI.
In high electric voltage applications, the connector must be insulated from these voltages, which can be over 10,000 volts. The connector should add negligible additional volume to the capillary column to avoid degrading separation resolution in electrophoretic applications. In addition, the connector should be able to act as an interface for connecting macroscale devices (such as injectors, fluid reservoirs, or sample depositors) to microscale capillary tubes. Finally, to aid in the simple manipulation of the connector, the connector must be reusable and simple to connect.
The varied uses of the connector in a number of applications require that the connector serve several different functions. Primarily the connector must be able to serve as a leak free, high pressure connector for two or more capillary tubes. The connector should provide a number of other functions as well. The connector could serve as a valve, enabling both the ability to close an end of a section of capillary tubing and the ability to route fluid from one capillary tube into a selectable second capillary tube. In addition, it would be useful for the connector to function as a manifold enabling the combination of the flow streams from a plurality of input capillary tubes to channel into a single output capillary tube or splitting a flow stream from a single capillary tube into multiple flow streams in multiple capillary tubes. The connector preferably would have negligible dead space volume, both as a connector and as a valve. Finally, the connector should enable connection of macroscale devices to microscale capillary tubes.
By combining these features within one connector, a multitude of uses become a possible. By using two such connectors at the two ends of a section of capillary tubes, a reversibly sealable nanoscale reaction chamber is formed. If the first connector also functions as a manifold, a plurality of input lines could flow into this nanoscale reaction chamber before it is sealed to allow for mixing a number of chemicals in the reaction. If the output line also functions as a manifold, once the reaction is complete, the mixture could be divided into multiple lines for sending flow streams to multiple analytical devices or to a waste reservoir.
In the past, several couplers have been developed to attach together the ends of capillary tubes. Some capillary connectors employ a ferrule with a longitudinal bore therethrough for inserting the ends of the capillaries to be coupled together and a compression fitting for mechanically compressing the ferrule to seal the connector. U.S. Pat. No. 5,288,113 to P. H. Silvis et al. teaches a heat-resistant connector for releasably joining end portions of two capillary tubes in end-to-end fashion for use in chromatography. U.S. Pat. No. 5,540,464 issued to Picha, describes a capillary connector where the ends of a capillary tube are press fit into a resilient member with a tapering throughbore. A split sleeve holds a pair of these members together in mutually facing alignment, with the throughbore aligned to enable two capillary tubes to come into fluid communication. U.S. Pat. No. 5,453,170 to S. Krstanovic et al. teaches coupling a capillary to a fine wire electrode to form an ion detector.
Some of the capillary connectors demonstrate the ability to couple together more than two capillaries. U.S. Pat. No. 5,487,569, issued to Silvis et al., teaches a glass insert with a plurality of legs connected at a central portion. Each leg has a tapered inner bore that receives one end of a capillary tube. On each of these legs is annularly mounted a connecting member containing a sealing ferrule for making a seal between the capillary and the leg. U.S. Pat. No. 5,494,641, issued to Krstanovic, describes a system for connecting any number of capillary tubes into a system by mounting the capillary tube within a cavity in a mechanical fastener. The capillary tube can then be attached to any apparatus that has been adapted to accept the fastener.
These capillary connectors function to link sections of capillary tubes. It would be advantageous to have a connector that could serve other functions.
Currently, there are several devices that have been used as valves or gates for capillaries. One capillary valve requires that the capillary tubes be attached to holes in a thin wafer, such as a silicon wafer. A flexible membrane is positioned on the opposite side of the wafer. By exerting pressure on the membrane, the membrane is pressed against the holes in the silicon wafer and the valve is closed. U.S. Pat. No. 5,492,555, issued to Strunk et al., describes a two dimensional capillary gas interface. One part of the device is a bimodal six way capillary valve. This valve comprises a cylindrical section with a longitudinal axis perpendicular to the plane containing the longitudinal axis of three sections of capillary tubes. The valve operates by rotation of the cylindrical section to align the ends of the capillary tube in the tangential plane of the cylinder with the ends of other capillary tubes bringing the section into fluid communication. Further rotation will bring the ends of the capillary tubes in the rotating cylindrical section out of communication with the capillary tubes, closing the valve. This valve has significant dead volume of several microliters.
The inner diameters of capillary tubes must connect to devices that are an order of magnitude or more larger. This has been a persistent problem for the field of microfluidics. Some attempts have been made to provide for a macroscale to microscale interface. For example, capillary tubes have been attached to pressurized r
Johnston Richard F.
Jovanovich Stevan B.
Roach David J.
Ronan Gregory J.
Molecular Dynamics, Inc.
Schneck David M.
Schneck Thomas
Stinson Frankie L.
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