Abstract:
An elastomeric vial cap used for sealing a vial container, but allowing pipette access to its containment fluid includes an annular flange portion for capping the vial and a sloped truncated cone portion to easily guide the pipette into the vial container. A tubular seal portion is configured to encircle the truncated cone portion and firmly engage an inside wall of the vial container with ease of insertion. A center flap portion is circumscribed by a channel at its top surface for penetration by the pipette and has a flex portion. The center flap portion separates around the perimeter of the channel but hinges at the channel above the flex portion and does not become dislodged. The ratio of the diameters of the pipette and the center flap portion is such that significant problems related to back-pressure and vacuum conditions do not exist during transfer of the containment fluid.

Description:
[0001]    This is a U.S. National Phase application of PCT/SE2008/051425, filed Dec. 9, 2008, which claims the benefit of priority to U.S. Provisional Application No. 61/012,541, filed Dec. 10, 2007, both of which are incorporated herein by reference in their entireties. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    This invention relates to a cap for use with a fluid container. In particular, this invention relates to a cap that encloses a vial container of various volumes and shapes. The vial cap allows for penetration by pipette or sampling tube while avoiding the problems associated with the conventional vial cap discussed below. 
         [0003]    A problem common to conventional vial caps is the propensity for the pipette or sampling tube to cause a back-pressure during filling or a vacuum condition during aspiration of the vial container. Back-pressure and vacuum conditions can cause errors in the precise transfer of fluid to or from the vial container. For example, a vacuum condition created in the vial container during a pipetting operation may cause the amount of fluid removed from the container to be less than the desired amount. Thus, problems transferring the precise amount of fluid from the vial container to the pipette or vice versa may occur when the pipette engages the vial cap and begins to add or withdraw containment fluid from the vial container. 
         [0004]    Another problem with conventional vial caps is lack of symmetry and flange portions that overhang the vial container. Robotic manipulating arms are designed to grasp vial containers of a particular diameter or width. When conventional vial caps are utilized with vial containers, they oftentimes have flanges or other extremities that extend beyond the outer perimeter of the vial container and may cause the robotic manipulating arm to fail to grasp the vial container properly. These conventional vial caps may cause a transport or pipetting operation to completely fail. 
         [0005]    Another problem of the conventional vial cap is that it may be damaged during a pipetting operation because the vial cap often has a shallow slope leading to a center flap portion of the vial cap. The shallow slope may cause the pipette to impinge on an area of the vial cap that is not penetrable rather than reaching the center flap portion. 
         [0006]    Another problem may occur when the pipette penetrates the center flap portion. The center flap portion may tear-away and fall into the containment fluid causing pipetting and/or contamination problems. 
         [0007]    What is needed is a vial cap that works well with robotic manipulating arms, maintains its operability during pipetting operations, keeps its center flap portion from falling into the containment fluid, and can facilitate the transfer of containment fluid without creating back-pressure or vacuum conditions that interfere with the proper pipetting of the containment fluid. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention describes a vial cap designed to enclose a vial container with fluid. 
         [0009]    An aspect of the present invention is to provide a vial cap engaged with a vial container that work well with robotic manipulating arms and pipetting equipment. 
         [0010]    Another aspect of the present invention is to provide an appropriately tapered outer conical wall for the vial cap that eases insertion of a pipette into the vial container while maintaining its operability during insertion of the pipette. 
         [0011]    Another aspect of the present invention is to eliminate the back-pressure and vacuum issues that arise during filling and removal of fluid from the vial container. 
         [0012]    Another aspect of the present invention is to provide a penetrable vial cap that keeps its center flap portion from falling into the containment fluid. 
         [0013]    Briefly, a vial cap may be manufactured of elastomeric material for sealing a vial container. Advantageously, the elastomeric material may include polypropylene, polystyrene, polyamide, polyethylene, Alathon M5040™, or any other suitable polymers. The vial cap may be cylindrical in shape and symmetric about a centerline coincident with its cylindrical axis. A top surface of the vial cap may have an annular flange that extends to an outer periphery of the vial cap. The flange may cover the vial container, but may not extend so far as to interfere with robotic manipulating arms. 
         [0014]    The vial cap may be designed to allow pipette access to containment fluid in the vial container after penetration of the vial cap by the pipette. A sloped truncated cone may be designed to easily guide the pipette into the vial container without destruction of the vial cap. The slope extends from the top surface of the flange towards the top surface of a center flap portion at an angle between about 40° to 60° with the top surface of the flange. 
         [0015]    The center flap portion may be circumscribed by a channel that is designed to tear-away from the truncated cone. The channel may be circular, elliptical, or polygonal at its perimeter. A cross-section of the channel may be u-shaped, v-shaped, or any other shape that facilitates tearing away from the truncated cone. The channel acts like a hinge at a flex portion because the thickness of elastomeric material below the channel at the flex portion is greater than the thickness of elastomeric material below the remaining perimeter of the channel. Thus, the channel above the flex portion allows the center flap portion to bend out of the way, but not to become dislodged and fall into the containment fluid when the pipette penetrates the center flap portion and tears the remaining channel away from the truncated cone. The ratio of the diameters of the penetrating pipette and the center flap portion may be designed so that back-pressure and vacuum conditions during transfer of the containment fluid may be prevented. 
         [0016]    A tubular seal that encircles the truncated cone may be designed to insert easily into the vial container and engage the inside walls of the vial container by an outer surface. The tubular seal may be cylindrically shaped having an outer diameter surface including a tapered portion, a band portion, and a cylindrical portion. The tapered portion allows for smooth insertion of the vial cap into the vial container, the band portion allows the vial cap to be engaged with the inside wall surfaces of the vial container, and cylindrical portion allows a snug fit between the end of the vial container and the vial cap. The band portion of the vial cap further includes an insertion segment, a flat segment, and an exit segment that advantageously allows the vial cap to be engaged with the vial container. Multiple band portions also may be provided along an extended outer surface of the tubular seal. 
     
    
     
       BRIEF DESCRIPTIONS OF THE DRAWINGS 
         [0017]    The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate embodiments of the invention, and, together with the general description given above and the detailed description given below, serve to explain various features of the invention: 
           [0018]      FIG. 1  is a top perspective view of an exemplary vial cap made in accordance with principles of the invention; 
           [0019]      FIG. 1A  is a bottom perspective view of the vial cap; 
           [0020]      FIG. 2  is a top view of the vial cap; 
           [0021]      FIG. 2A  is a bottom view of the vial cap; 
           [0022]      FIG. 3  is a cross-sectional view of the vial cap of  FIG. 1 ; 
           [0023]      FIG. 4  is a cross-sectional view of an exemplary vial cap and inserted pipette; 
           [0024]      FIG. 5  is a top perspective view of 2 ml flat bottom vial container; 
           [0025]      FIG. 5A  is a top perspective view of 2 ml rounded bottom vial container; 
           [0026]      FIG. 5B  is a top perspective view of 1 dram vial container; 
           [0027]      FIG. 5C  is a top perspective view of 2 dram vial container; 
           [0028]      FIG. 5D  is a top perspective view of 12 mm×100 mm flat bottom vial container; and 
           [0029]      FIG. 5E  is a top perspective view of 12 mm×100 mm rounded bottom vial container and an engaged exemplary vial cap. 
           [0030]      FIG. 6  is a side elevation view of another embodiment of the vial cap. 
           [0031]      FIG. 7  is a side elevation view of a fluid transfer system. 
       
    
    
       [0032]    The above have been offered for illustrative purposes only, and are not intended to limit the scope of the invention of this application, which is described more fully in the drawings and claims sections set forth below. 
       DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0033]    The inventor has found conventional vial caps to suffer from problems including vacuum lock and back-pressure during transfer of the containment fluid and, contamination of the containment fluid by pieces of the vial cap. The present invention integrates features that can improve the performance and utility of the vial cap to overcome deficiencies of current designs and provide general improvements in the art. 
         [0034]    The vial cap can be various sizes depending on the size of vial container and pipette selected. Dimensions are provided as examples herein and it should be understood that variations are possible.  FIGS. 1-5E  illustrate an embodiment of a vial cap  50 .  FIG. 1  shows a top perspective view of vial cap  50 . The vial cap includes an annular top surface  11  that meets a sloping outer conical wall surface  21  and narrows to meet a channel  41  that circumscribes a top surface  42  at its center. See also  FIG. 2  for a top view of these features. In  FIG. 1A , a bottom perspective view shows an outer surface  31  that extends perpendicularly from a bottom surface  13  of a flange.  FIG. 2A  is a bottom view of the features shown in  FIG. 1A . A unifying view of the interrelationship of the above mentioned features can be seen in  FIG. 3 , which is a cross-sectional view of  FIG. 2 .  FIG. 3  displays features of the vial cap  50  including the features of the flange  10 , a truncated cone  20 , a tubular seal  30 , and a center flap portion  40 . 
         [0035]    As shown in  FIG. 3 , the flange  10  is annular and disposed at the periphery of the vial cap  50 . The bottom surface  13  of the flange may extend out from a cylindrical portion  32  of the outer surface of the tubular seal  30 . The flange  10  may extend over the thickness of a vial container&#39;s wall and act like a cover. The symmetry and extension of the flange  10  over the vial container&#39;s wall reduces the possibility of interference with robotic manipulating arms. Robotic manipulating arms are designed to grasp vial containers of a particular diameter or width. Vial caps that do not have flanges or other extremities that extend beyond the outer perimeter of the vial container improve the robotic manipulating arm&#39;s ability to grasp the vial container. 
         [0036]    The flange  10  is connected to the truncated cone  20  and tubular seal  30 . The tubular seal  30  may be cylindrical in shape and may extend from the bottom surface  13  of the flange  10  and an inner conical base  22  toward a bottom surface  36  of the tubular seal, for example, as shown in  FIG. 3 . While an inner surface  35  of the tubular seal may be cylindrical and perpendicular to the top surface  11  of the flange, the outer surface  31  of the tubular seal changes slope at different points along its length. A tapered portion  34  of the outer surface of the tubular seal may begin, for example, at the bottom surface  36  and may taper up in a direction away from the centerline of the vial cap for ease of insertion into the vial container. The tapered portion  34  allows for smooth insertion of the vial cap into the vial container. 
         [0037]    The outer surface  31  may change slope again when a band portion  33  of the outer surface of the tubular seal is encountered. In  FIG. 3 , the band portion  33  is wider than the outer diameter of the tapered portion  34  at the bottom surface  36 . An insert slope segment  33   a  of the band portion  33  may increase in slope over the tapered portion  34 , and then decrease in slope until the band portion  33  enters a flat segment  33   b  where the slope is substantially parallel to the cylindrical portion  32  of the outer surface of the tubular seal. The band portion  33  then enters an exit slope segment  33   c  where the exit slope segment decreases in slope and terminates at the cylindrical portion  32  of the outer surface of the tubular seal, for example, as shown in  FIG. 3 . 
         [0038]    In another embodiment of the present invention, multiple band portions  33  are provided along an extended outer surface  31  of the tubular seal  30 , for example, as shown in  FIG. 6 . The extended length of the outer surface  31  of the tubular seal  30  may be necessary in order to fit the additional band portions along its length. Multiple band portions  33  may provide added engagement between the vial cap  50  and the vial container. 
         [0039]    The cylindrical portion  32  of the outer surface  31  of the tubular seal  30  runs parallel to the inner surface  35  of the tubular seal and may have the same diameter as the beginning outer diameter of the tapered portion  34 , for example, as shown in  FIG. 3 . The cylindrical portion  32  may be perpendicular to the bottom surface  13  of the flange  10  and ends there. The cylindrical portion  32  allows a snug fit between a mouth of the vial container and the vial cap  50 . 
         [0040]    The truncated cone  20  extends from the top surface  11  of the flange  10  and the tubular seal  30  down towards the center flap portion  40  of the vial cap  50 . The slope of the outer conical wall surface  21  of the truncated cone  20  may guide the pipette or sampling tube toward the center flap portion  40 . The slope of the outer conical wall surface  21  may extend from the top surface  11  of the flange  10  towards the top surface  42  of the center flap portion at an angle between about 40° to 60° with the top surface  11  of the flange  10 . An inner conical wall surface  23  runs substantially parallel to the outer conical wall surface  21 , and may begin at the inner conical base  22  and may end at an inner conical plateau  24 , for example, as shown in  FIG. 3  and  FIG. 1A . 
         [0041]    The center flap portion  40  may include the channel  41  and a flex portion  45 . The flex portion  45  may be an extension of the inner conical wall surface  23  to a bottom surface  43  of the center flap portion  40 , for example, as shown in  FIG. 3 . The bottom surface  43  may be a variety of shapes depending on the shape of the channel&#39;s perimeter and inner conical plateau  24  located above it. For example, the flex portion  45  may be shaped like the keystone-shaped flex portion shown in  FIGS. 1A and 2A . A chamfered surface  44  of the center flap portion  40  may be provided. The chamfered surface  44  may slope upwardly from the bottom surface  43  at an angle until it reaches the inner conical plateau  24  above it. 
         [0042]    The top surface  42  of the center flap portion, located below the top surface  11  of the flange, may be circumscribed by the channel  41 , for example, as shown in  FIGS. 1 ,  2 , and  3 . The channel  41  may, for example, be circular, elliptical, or polygonal at its perimeter. A cross-section of the channel  41  may be u-shaped, v-shaped, or other shape that facilitates tearing away from the truncated cone. The cross-section dimensions of the channel  41  may be measured in fractions of millimeters, and the inner conical plateau  24  may be located fractions of millimeters below the bottom of the channel  41 . The difference in depth between the channel  41  and the inner conical plateau  24  below it serves to reduce the thickness of the center flap portion  40  along the perimeter of the channel  41 , for example, as shown in  FIG. 3 , so that the pipette can easily push the center flap portion  40  out-and-away from the truncated cone  20 . 
         [0043]    Above the flex portion  45 , however, the channel  41  acts like a hinge instead of a tear-away feature. The vial cap material below the channel  41  at the flex portion  45  is thicker compared to the thickness of material below the rest of the channel perimeter, allowing the flex portion  45  to resist tearing compared to the remainder of the channel  41 . The channel  41  above the flex portion  45  may act like a hinge so that a force exerted by a pipette tears the center flap portion  40  away from the truncated cone, for example, along the rest of the channel perimeter. Thus, the torn away center flap portion  40  flexes downward from the hinge-like channel  41  above the flex portion  45  due to the force exerted by the pipette, but center flap portion  40  does not become dislodged and fall into the vial container.  FIG. 4  of the drawings shows the flex portion  45  in a cross-sectional view of the vial cap  50  with inserted pipette P. The diameter of the center flap portion  40  may be, for example, 50% larger than the diameter of the inserted pipette P used with such vial containers. Consequently, the vial containers do not experience significant problems relating to back-pressure or vacuum conditions during the pipetting operation. 
         [0044]      FIGS. 5-5E  show some of the assortment of vial containers to which the vial cap can be engaged. The vial containers range in volume and shape, but the drawings show them having the same size openings.  FIG. 5E  further shows the vial cap  50  engaged with the vial container. It is envisioned that a plurality of vial caps engaged to vial containers may be handled by robotic manipulating arms and/or receive robotic operated pipettes that penetrate the center flap portions. 
         [0045]    A combination of the vial cap  50  with the vial container e.g., like the one in  FIG. 5E , provides a sealed vessel assembly  60  that may be partially or completely filled with a fluid, or completely evacuated to create a vacuum. The vessel assembly  60  maintains its initial pressure condition until such time that it is penetrated in a pipetting operation as previously described. 
         [0046]    A fluid transfer system  70  including the vessel assembly  60  (i.e., the vial cap  50  and vial container), and pipette P of the present invention, for example as shown in  FIG. 7 , is also contemplated. The fluid transfer system  70  may be used for transferring fluid from the vial container to the pipette P or vice versa with precision, and without creating back-pressure and vacuum issues that may arise during filling and removal of fluid. The fluid transfer system  70  may also comprise a robotic manipulating arm  71  for moving the vessel assembly  60  into the proper position for penetration by the pipette P. 
         [0047]    The vial cap  50  may be made of an elastomeric material including polypropylene, polystyrene, polyamide, polyethylene, Alathon M5040™, or other suitable polymers. Alathon M5040™ is a high-density polyethylene preferred for its resiliency and resistance to contamination. The Alathon M5040™ vial cap may be injection molded to make the vial cap  50  a monolithic part that can be easily mass-produced. 
         [0048]    In one embodiment of the present invention, the overall length of the vial cap  50  from the top surface  11  of the flange  10  to the bottom surface  36  of the tubular seal  30  is about 7.00 mm. The outer periphery of the flange portion  10  is about 11.65 mm, while the sloping outer conical wall surface  21  of the truncated cone  20  has an outer diameter of about 7.85 mm and an inner diameter of about 4.00 mm. The slope of the outer conical wall surface  21  declines about 48.4° from the top surface  11  of the flange  10  to the channel  41  disposed at the top surface  42  of the center flap portion  40 . 
         [0049]    The top surface  42  of the center flap portion  40  is about 2.90 mm below the top surface  11  of the flange, while the bottom surface  43  of the center flap portion  40  is located about 3.30 mm below the top surface  11  of the flange. The circular channel  41  disposed at the top surface  42  is u-shaped in cross-section having a depth of 0.10 mm and width of 0.15 mm. The inner conical plateau  24  has a depth about 3.00 mm below the top surface  11  of the flange, slightly below that of the bottom of the channel  41  so that most of the channel perimeter  41  has a reduced thickness below it. The center flap portion  40  has the reduced thickness along about 94% of the channel perimeter  41 . 
         [0050]    The center flap portion  40  connects with the truncated cone  20  and indirectly with the flange  10  and tubular seal portion  30 . The inner surface  35  of the tubular seal  30  has an inner diameter of about 7.85 mm and the outer diameter of the tapered portion  34  of the outer wall surface  31  of the tubular seal  30  is about 9.90 mm at the bottom surface  36 . Thus, the thickness of the tubular seal  30  is about 2.05 mm at the bottom surface  36 . 
         [0051]    The outer wall surface  31  of the tubular seal  30  has distinct areas beginning at the tapered portion  34  and progressing to the band portion  33  and the cylindrical portion  32 . The band portion  33  is about 2.00 mm long and disposed about 2.80 mm from the bottom surface  36 , and may extend about 0.30 mm wider than the outer diameter of the tapered portion  34  at the bottom surface  36 . The other end of the band portion  33  terminates at the cylindrical portion  32 , which is 1.50 mm long and extends to the bottom surface  13  of the flange  10 . 
         [0052]    While the present invention has been disclosed with reference to certain preferred embodiments, numerous modifications, alterations, and changes to the described embodiments are possible without departing from the sphere and scope of the present invention, as defined in the appended claims. Accordingly, it is intended that the present invention not be limited to the described embodiments, but that it have the full scope defined by the language of the following claims, and equivalents thereof.