Chemical apparatus and process disinfecting – deodorizing – preser – Control element responsive to a sensed operating condition
Reexamination Certificate
1999-03-02
2001-11-20
Warden, Jill (Department: 1743)
Chemical apparatus and process disinfecting, deodorizing, preser
Control element responsive to a sensed operating condition
C422S070000, C422S091000, C422S105000, C422S105000, C436S174000, C436S180000, C210S198200
Reexamination Certificate
active
06319476
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to fluid connectors. More specifically, the invention relates to fluid connectors used for coupling fluid conduits to microfluidic devices.
BACKGROUND OF THE INVENTION
Devices for performing chemical analysis have in recent years become miniaturized. For example, microfluidic devices have been constructed using microelectronic fabrication and micromachining techniques on planar substrates such as glass or silicon which incorporate a series of interconnected channels or conduits to perform a variety of chemical analysis such as capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC). Other applications for microfluidic devices include diagnostics involving biomolecules and other analytical techniques such as micro total analysis systems (&mgr; TAS). Such devices, often referred to in the art as “microchips,” also may be fabricated from plastic, with the channels being etched, machined or injection molded into individual substrates. Multiple substrates may be suitably arranged and laminated to construct a microchip of desired function and geometry. In all cases, the channels used to carry out the analyses typically are of capillary scale dimension.
To fully exploit the technological advances offered by the use of microfluidic devices and to maintain the degree of sensitivity for analytical techniques when processing small volumes, e.g., microliters or less, connectors which introduce and/or withdraw fluids, i.e., liquids and gases, from the device, as well as interconnect microfluidic devices, are a crucial component in the use and performance of the microfluidic device.
A common technique used in the past involves bonding a length of tubing to a port on the microfluidic device with epoxy or other suitable adhesive. Adhesive bonding is unsuitable for many chemical analysis applications because the solvents used attack the adhesive which can lead to channel clogging, detachment of the tubing, and/or contamination of the sample and/or reagents in or delivered to the device. Furthermore, adhesive bonding results in a permanent attachment of the tubing to the microfluidic device which makes it difficult to change components, i.e., either the microfluidic device or the tubing, if necessary. Thus assembly, repair and maintenance of such devices become labor and time intensive, a particularly undesirable feature when the microfluidic device is used for high throughput screening of samples such as in drug discovery.
To avoid problems associated with adhesive bonding, other techniques have been proposed in the past, e.g., press fitting the tubing into a port on the microfluidic device. However, such a connection typically is unsuitable for high-pressure applications such as HPLC. Additionally, pressing the tubing into a port creates high stress loads on the microfluidic device which could lead to fractures of the channels and/or device.
Other methods involved introducing liquids into an open port on the microfluidic device with the use of an external delivery system such as a pipette. However, this technique also is undesirable due to the possibility of leaks and spills which may lead to contamination. In addition, the fluid is delivered discretely rather than continuously. Moreover, the use of open pipetting techniques does not permit the use of elevated pressure for fluid delivery such as delivered by a pump, thereby farther restricting the applicability of the microfluidic device.
Therefore, a need exists for an improved microfluidic connector which is useful with all types of microfluidic devices and provides an effective, high pressure, low fluid dead volume seal. The connector also should overcome the disadvantages and limitations described above, including chemical compatibility problems resulting from the use of adhesive bonding techniques.
SUMMARY OF THE INVENTION
The present invention is directed to a fluid connector which couples a microfluidic device, e.g., a chemical analysis device, to a fluid conduit used for introducing and/or withdrawing liquids and gases from the microfluidic device. A fluid connector of the invention provides a fluid-tight seal with low fluid dead volume which is able to withstand high-pressure applications, e.g., 3000 pounds per square inch (psi) or greater.
A fluid connector of the invention includes a housing, a clamping member, a first load support surface and a sealing member. The housing has a bore extending through it for receiving the fluid conduit and for positioning one end of a fluid conduit for connection to a port of a microfluidic device. The housing typically has a top plate and a bottom plate. The top plate often has a bore extending completely through it and the bottom plate supports the microfluidic device adjacent to the bore.
The clamping member is located remotely from the end of the fluid conduit which communicates with the microfluidic device. In use, the clamping member directly or indirectly applies an axial force to the first load support surface, e.g., a ferrule or protrusion on the fluid conduit, which operatively is coupled to the fluid conduit between the clamping member and the end of the fluid conduit. The clamping member may be a compression screw or other similar device. The clamping member also may be a surface of the top plate of the housing such that as the top plate and bottom plate are mated, an axial force is applied to the first load support surface thereby urging the fluid conduit towards a port on the microfluidic device.
The sealing member is interposed between the end of the fluid conduit and the surface area surrounding the microfluidic device port. At least the portion of the sealing member adjacent to the port of the microfluid device is made of a pliant material, thereby defining a pliant portion of the sealing member. In this respect, the pliant portion of the sealing member also is in communication with the end of the fluid conduit which is coupled to the microfluidic device. A first bore of the sealing member extends through the sealing member which permits fluid communication between the fluid conduit and the port of the microfluidic device.
In its simplest form, the sealing member is a gasket or flat elastomeric “washer.” However, additional structure and/or designs are contemplated by this invention as disclosed herein or which are known to skilled artisans. For example, the sealing member may have a second bore. The second bore of the sealing member typically is sized and shaped to match the outer diameter of the fluid conduit thereby creating a second load support surface and permitting the conduit to be maintained in a fixed relation with respect to the microfluidic device port. The sealing member often is formed of a pliant material such as an elastomer or a polymer. In using this type of sealing member, the axial force applied to the first load support surface urges the end of the fluid conduit against the second load support surface while simultaneously urging the pliant portion of the sealing member against the surface area surrounding the port of the microfluidic device to provide a fluid-tight face seal.
Other structures which may be present in a fluid connector of the invention include an elastic member such as a spring, and/or an alignment mechanism. The elastic member may be used to facilitate and maintain the fluid-tight face seal especially when the fluid connector experiences a range of temperatures. The alignment mechanism readily facilitates connection of the fluid conduit and the microfluidic device without requiring precise manual positioning of the components. The alignment mechanism also permits the fluid connector of the invention to be used in automated techniques.
The present invention provides several advantages which are especially important for conducting chemical analysis using microfluidic devices. For example, the fluid connector of the invention provides a seal which extends across essentially the entire face of the fluid conduit, thereby minimizing fluid dead volume between the end of the
Stokes Jeffrey H.
Victor, Jr. Richard L.
Handy Dwayne K.
PerSeptive Biosystems Inc.
Testa Hurwitz & Thibeault LLP
Warden Jill
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