Abstract:
A gasket for sealing interfaces between a micro-machined device and a macroscopic connection to the device. The gasket can include an o-ring, a frame, a tool post and a notch. Alignment of the tool post with a dimple formed in or through a surface of a component adjacent to the gasket facilitates alignment of the gasket. The notch and frame can also facilitate alignment of the gasket.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates generally to gaskets used for providing seals between micro-machined devices and connections to the micro-machined devices.  
           [0003]    2. Description of the Related Art  
           [0004]    [0004]FIG. 1 illustrates a cross-sectional view of an apparatus  10  according to the related art. The apparatus  10  illustrated in FIG. 1 includes a planar manifold  20  having a manifold inlet  30  on one of its surfaces and a manifold outlet  40  on another of its surfaces. In between the inlet  30  surface and outlet  40  surface are a series of micro-machined components that allow the apparatus  10  to function according to a specified purpose. For example, the apparatus  10  could function as part of a gas chromatograph, as discussed in U.S. Pat. No. 5,567,868 to Craig et al., incorporated herein in its entirety by reference.  
           [0005]    Adjacent to the surface of the planar manifold  20  that includes the inlet  30  are positioned, sequentially, an o-ring gasket  90  and a diffusion-bonded plate  80 . The diffusion-bonded plate  80  effectively “squeezes” the gasket  90  and, if the gasket  90  is positioned properly relative to the inlet  30  and the plate  80 , the squeezed gasket  90  is reshaped to form seals with the planar manifold  20  and the diffusion-bonded plate  80 . The pathway to the inlet  30  (through the gasket  90  and the diffusion-bonded plate  80 ) allows for a sample to be introduced into the apparatus  10 .  
           [0006]    [0006]FIG. 2 illustrates an elevated, top perspective view of the related art o-ring gasket  90  included in FIG. 1. The o-ring gasket  90  includes a web  100  and several o-rings  110  molded into the web  100 . When the gasket  90  is properly positioned relative to a planar manifold  20 , the o-rings  110  in the gasket  90  are centered around the inlets  30  of the manifold  20 . In this position, when squeezed by the diffusion-bonded plate  80 , the gasket  90  forms seals with the planar manifold  20  and the diffusion-bonded plate  80 . These seals prevent the sample introduced into the planar manifold  20  from leaking out of the apparatus  10 .  
           [0007]    Among the disadvantages of the related art apparatus  10  and related art o-ring gasket  90  is the inherent difficultly of properly aligning the o-rings  110  relative to the inlets  30 . Unless care and caution are used to position the o-ring gasket  90 , proper seals will not be formed and the sample may leak out of the apparatus  10 . The sample will also leak out of the system if the o-ring gasket  90  is not properly aligned with respect to the diffusion-bonded plate  80 .  
           [0008]    Hence, what is needed is a method of conveniently and cost-effectively manufacturing an o-ring gasket that can be conveniently positioned between a planar, micro-machined device and/or a plate that compresses the o-ring gasket to create a seal.  
         BRIEF SUMMARY OF THE INVENTION  
         [0009]    According to one embodiment, a gasket for sealing an interface to a micro-machined device that includes a web for placement adjacent to the micro-machined device wherein the web includes an aperture and a tool post protruding from a first surface of the web.  
           [0010]    According to another embodiment, a gasket for creating an interface to a micro-machined device that includes a web for placement adjacent to the micro-machined device wherein the web includes an aperture and a frame protruding from a first surface of the web.  
           [0011]    According to yet another embodiment, a micro-injector that includes an injector die and a first o-ring gasket adjacent to a first surface of the injector die, wherein the first o-ring gasket includes a web adjacent to the injector die, an o-ring in the web, and a tool post protruding from a surface of the web. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    The invention will be described by way of example, in the description of exemplary embodiments, with particular reference to the accompanying drawings in which:  
         [0013]    [0013]FIG. 1 illustrates a cross-sectional view of an apparatus according to the related art wherein an o-ring gasket forms a seal between a planar manifold and a diffusion-bonded plate;  
         [0014]    [0014]FIG. 2 illustrates a top perspective view of an o-ring gasket according to the related art wherein o-rings are included within the webbing of the gasket;  
         [0015]    [0015]FIG. 3 illustrates a top perspective view of an o-ring gasket wherein o-rings are included in the webbing of the gasket and tool posts protrude from the webbing;  
         [0016]    [0016]FIG. 4 illustrates a bottom perspective view of an o-ring gasket wherein a frame protrudes from the perimeter of the webbing;  
         [0017]    [0017]FIG. 5 illustrates a top perspective view of an o-ring gasket wherein a notch is formed in the frame and webbing; and  
         [0018]    [0018]FIG. 6 illustrates a cross-sectional view of an apparatus positioned between two o-ring gaskets and a heater element. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0019]    [0019]FIG. 3 illustrates an o-ring gasket  90  according to one embodiment of the present invention. The o-ring gasket  90  illustrated in FIG. 3 includes a web  100  containing apertures. Protruding from the web  100  are a plurality of tool posts  120 . Although the apertures in FIG. 3 are o-rings  110 , other configurations for apertures that provide a pathway through the web  100  of the gasket  90  are also within the scope of the present invention.  
         [0020]    The web  100  can be made from any material capable of containing apertures that provide a pathway through the web  100  and that also provides sufficient structural support for tool posts  120  or other objects that protrude from the web  100 . According to the certain embodiments of the present invention, the web  100  is made from a rigid material, such as, but not limited to, a plastic, ceramic or metal. According to certain embodiments, the material of the web  100  is chosen to be resistant to corrosion from gases or liquids that flow through the planar manifold  20  discussed above. The dimensions of the web  100  can include, but are not limited to, a quarter of a millimeter of thickness, and several centimeters of length and width.  
         [0021]    Although gaskets  90  within the scope of the present invention can be placed adjacent to any planar manifold  20  such as an injector die used in a gas chromatography apparatus, the gaskets  90  can also be used in conjunction with other types of planar devices. Specific examples of other planar devices within the scope of the present invention include, but are not limited to, micro-machined valves and sensors, and any micro-electro-mechanical systems (MEMS) device.  
         [0022]    The o-rings  110  that can be used as the apertures in the web  100  include commercially-available o-rings  110  that have one-half-millimeter inner diameters. However, any dimension of o-ring  110  that allows for a sample to travel into the planar manifold  20  to which the gasket  90  is adjacent and with which the gasket  90  creates a substantially leak-proof seal is also within the scope of the present invention.  
         [0023]    According to certain embodiments of the present invention, the o-ring  110  can be thicker than the web  100 . For example, if a web  100  with a one-quarter-millimeter thickness is chosen, an o-ring  110  with a one-half-millimeter thickness can be molded into the web  100 . Using an o-ring  110  that is thicker than the web  100  in which it is included allows for a diffusion-bonded plate  80  to compress the o-ring  110  between the plate  80  and the surface of the planar device adjacent to the o-ring  110 . This compression forms seals between the surface and the o-ring  110  and between the o-ring  110  and the plate  80 .  
         [0024]    According to certain embodiments, one or more o-rings  110  in the web  100  can be made from an elastomer material. Also, the o-rings  110  can include materials that are durable under compressive stresses such as, but not limited to, those stresses experienced when the o-ring gasket  90  is compressed by the diffusion-bonded plate  80 . Further, the o-ring  110  can include material that is chemically un-reactive with the sample introduced into the planar device.  
         [0025]    The tool posts  110  illustrated in FIG. 3 protrude from only one surface of the web  100 . However, in other embodiments of the present invention, the tool posts  110  can protrude from more than one surface of the web  100  (See FIG. 6). As shown in FIG. 3, the tool posts  120  can protrude different distances from the surface of the web  100  and can have different geometries. Examples of such geometries include, but are not limited to, cylindrical shapes, hemispherical shapes, and tapered shapes. Also, the tool posts  120  can be made from rigid materials such as, but not limited to, hard plastics, ceramics and metals. One or more tool posts  120  can be arranged in any configuration on the web  100 .  
         [0026]    Although o-rings  110  are illustrated in FIG. 3, other apertures and geometries can be used within the scope of the present invention. For example, square, triangular, or irregularly shaped apertures can be used, so long as a seal can be formed between the gasket  90  and the planar device surface to which the gasket  90  is adjacent.  
         [0027]    One or more apertures or o-rings  110 , such as those illustrated in FIG. 3, can be positioned almost anywhere on the web  100 . The number of total apertures is not limited in the present invention, so long as the gasket  90  does not lose its structural integrity due to having too many holes formed within it.  
         [0028]    According to certain embodiments of the present invention, some of the o-ring  110  are “filled in” by another material and do not provide pathways through the web  100 . These “filled in” o-rings can be used to relieve and/or redistribute compressive stresses in other o-rings  110  and in the web  100 .  
         [0029]    According to certain embodiments of the present invention, the gasket  90  contains a number of apertures equal to the total sum of inlets  30  and outlets  40  in the planar manifold  20  adjacent to the gasket  90 . These embodiments can be used in planar devices where a gasket  90  is needed on both a first surface of the apparatus  10  containing inlets and a second surface of the apparatus  10  containing outlets. Embodiments that allow for identical gaskets  90  to be placed on both surfaces of the planar device only require that one type of gasket  90  be designed and manufactured. Such embodiments can therefore reduce the overall cost of manufacturing the apparatus  10 .  
         [0030]    [0030]FIG. 4 illustrates a bottom, perspective view of a gasket  90  according to another embodiment of the present invention. In addition to the web  100 , apertures, and protrusions discussed above, the o-ring gasket  90  illustrated in FIG. 4 includes a frame  130 . This frame  130  can protrude from one or more surfaces of the web  100  and allows for the o-ring gasket  90  to be more easily positioned relative to the device adjacent to the gasket  90 .  
         [0031]    The frame  130  can be made from a rigid material or a flexible material. According to certain embodiments, the web  100  and the frame  130  are made from elastomers that can be “stretched” to fit around the perimeter of the planar device to which the gasket  90  is adjacent. Regardless of whether the frame  130  is stretched around the perimeter of the device surface or fits without stretching, once the frame  130  is in place, all of the apertures are, at the same time, also positioned relative to the device in a manner conducive to forming seals.  
         [0032]    The frame  130  can also be positioned relative to the diffusion-bonded plate  80  (or other planar surface) in a similar manner. For example, if the frame  130  is stretched or otherwise positioned around the perimeter of the diffusion-bonded plate  80 , the o-rings  110  in the gasket  90  will, at the same time, line up with apertures in the plate  80 .  
         [0033]    [0033]FIG. 5 illustrates yet another embodiment of the present invention wherein a gasket  90  includes a notch  140  formed within one side of it. Although only one notch  140  is illustrated in FIG. 5, more than one notch  140  can be present in certain gaskets  90  within the scope of the present invention.  
         [0034]    The notch  140  can be formed exclusively in the frame  130  portion of the gasket  90 , exclusively in the web  100 , or can be formed in the frame  130  and in the web  100 . The dimensions and geometry of the notch  140  are not restricted by the present invention. For example, rectangular, hemi-spherical, irregularly shaped or triangular notches  140  can be formed and the widths, diameters, and lengths of the notches  140  can vary.  
         [0035]    [0035]FIG. 6 is a cross-sectional view of another embodiment of the present invention illustrating a planar manifold  20  that takes the form of an injector die for in a micro-injector for a gas chromatography apparatus  10 . The planar manifold  20  die is positioned between a first o-ring gasket  90  and a heater  150  that is included to help prevent condensation in the die of the gas to be analyzed. To the outside of the first o-ring gasket  90  is positioned a first diffusion-bonded plate  80  and to the outside of heater  150  is positioned a second o-ring gasket  90 . To the outside of the second o-ring gasket  90  is positioned a second diffusion-bonded plate  80 .  
         [0036]    The first o-ring gasket  90  contains two tool posts  120 , in this example, that each fit into one of the corresponding dimples  160  formed on the surfaces of the injector die and first diffusion-bonded plate  80 , respectively. Dimples  160  that accommodate the presence of the tool posts  120  in the second o-ring gasket  90  are also present on the surfaces of the heater  150  and second diffusion-bonded plate  80 .  
         [0037]    Although dimples  160  are illustrated in FIG. 6, the tool posts  120  may, according to other embodiments of the present invention, fit into or protrude through other features such as, but not limited to, holes that go completely through the component to which the gasket  90  is adjacent. For example, instead of the dimples  160  shown, some embodiments of the present invention have holes that accommodate the tool posts  120  and go through either the diffusion-bonded plate  80 , the heater  150  or a fitting  70 .  
         [0038]    The fitting  70  is attached, generally by welding, to the first diffusion-bonded plate  80 . A connector  60  that allows for a sample to be introduced into the injector die is fastened to the fitting  70 . Various fittings  70  can be used according to certain embodiments of the present invention. These fittings  70  include, but are not limited to, ZDV fittings, press-fit unions and nut and ferrule sets. The fitting  70  can include one or more dimples  160  that, when properly aligned with respect to the first gasket  90 , surrounds one of the tool posts  160  on the first gasket  90 .  
         [0039]    The dimples  160  in conjunction with tool posts  120  provide for easier positioning of the gaskets  90 . In other words, the gaskets  90  are designed such that, when the tool posts  120  rest in the dimples  160 , the apertures or o-rings  110  are properly positioned respective to the inlets  30  and outlets  40  to accommodate the formation of seals.  
         [0040]    Although not shown, both o-ring gaskets  90  can have frames  130  protruding from their surfaces that fit around the perimeters of the components to which they are adjacent. As discussed above, these frames  130  also aid in properly positioning the gasket  90 .  
         [0041]    Also, the second o-ring gasket  90  can have one or more notches  140  that allow for electrical connections to be made to the heater  150 , enabling the temperature of the heater  150  to be regulated. These notches  140  also can be of such a geometry that the heater  150  only fits through the notch  140  in one orientation. This aids in properly positioning the heater  150 .  
         [0042]    According to certain embodiments, the o-rings  110  in the second o-ring gasket  90  can be of a thickness that is greater than the combined thickness of the web  100  and heater  150 . That way, the o-ring  110  can go completely through an opening in the heater  150  and form seals with the injection die and the second diffusion bonded plate  80 .  
         [0043]    To summarize, when positioning the components illustrated in FIG. 6 relative to each other, the tool posts  120 , frames  130 , notches  140  and dimples  160  are used. When each of the tool posts  120  is positioned in a dimple  160  and/or when the frame  130  is properly fit around one or more of the components adjacent to the gasket  90 , the apertures or o-rings  110  are properly positioned around either an inlet  30  or outlet  40  to accommodate the formation of a seal. Hence, forming seals becomes easier and more reliable. Also, since certain gaskets  90  of the present invention can only be properly positioned in one orientation, the placement of the gasket  90  is simplified since the user does not have difficulty in determining front from back and top from bottom of the gasket  90 .  
         [0044]    Further, some gaskets  90  according to the present invention have fewer, less complex parts than some earlier sealing mechanisms that incorporated separate o-rings that were not included in webbing. Even further, some gaskets  90  according to the present invention are easier to clean.  
         [0045]    In certain embodiments, only some of the o-rings  110  are positioned around inlets  30  and outlets  40  while other o-rings  110  are used as compressive stress distributors. The stress-distributing o-rings  110  can be filled in since they do not need to allow gas to flow through.  
         [0046]    The foregoing detailed description has been given for understanding exemplary implementations of the invention only and no unnecessary limitations should be understood there from as modifications will be obvious to those skilled in the art without departing from the scope of the appended claims and their equivalents.