PERFORABLE CAP FOR A BIOLOGICAL SPECIMEN CONTAINER

Abstract: The present invention provides for a cap (10) for sealing a biological sample tube for use in an automated analyzer. The cap comprises a skirt portion (22) forming the side wall of the cap and having thread members (24) on the interior surface of the side wall, the skirt portion having an open top with an inwardly extending rim (26). The cap also includes a top portion (30) of a flexible self-sealing elastomeric material sealed to the skirt portion through engagement with the inwardly extending rim. The top portion may also include an upwardly extending sealing surface (49) defining a cavity which may be sealed against the external environment when the sealing surface contacts a planar surface. The present invention also provides for a sample tube (12) which has generally cylindrical side wall (14) with an open top (16) and bottom and thread members (18) provided on the exterior of the side wall near the top. The tube further has a cone-shaped sample holding divider (20) located in the interior of the tube intermediate the top and bottom.

Description: PERFORABLE CAP FOR A BIOLOGICAL SPECIMEN CONTAINER FIELD OF THE INVENTION The present invention relates to a perforable sealing cap for biological specimen containers, particularly for use in automated sample accessioning equipment and automated clinical analyzers. BACKGROUND OF THE INVENTION In the medical laboratory area over the past few years, there has been increased risks associated with the handling of specimens for analysis. As such, there has been a major shift towards use of automated analyzers as well as automated sample handling equipment. The use of such sample handling equipment and analyzers, however, has not completely diminished the risk of contact with potentially infectious agents and other harmful agents as, for example, many analyzers require that a sample probe be inserted into the sample tube to pick up the sample for analysis by the analyzer. In the past, such sample tubes have generally been open and uncovered, however, in the last number of years, there has been a shift toward providing for caps for such tubes which will allow the passage of the probe through the cap to allow the probe to pick up the sample from the tube. There have been a number of problems associated with such caps as after passage of the probe through the top of the cap, a hole remains in the cap that does not completely seal the contents of the tube from the outside environment. Additionally, there have been instances where, owing to the friction between the cap material and the probe, the probes have been detached from the analyzer. SUMMARY OF THE INVENTION The present invention provides for a cap for sealing a biological sample tube for use in an automated analyzer. The cap comprises a skirt portion forming the side wall of the cap and having thread members on the interior surface of the side wall, the skirt portion having an open top with ah inwardly extending rim. The cap also includes a top portion of a flexible elastomeric material sealed to the skirt portion through engagement with the inwardly extending rim and closing off the open top of the skirt portion. The flexible elastomeric material is selected to permit puncture by a needle or probe such that the hole formed by the puncture of the needle or probe permits passing of the needle or the probe therethrough and reseals after removal of the needle or probe. In a preferred embodiment, the present invention provides for a cap for sealing a biological sample tube for use in automated sample accessioning equipment and automated clinical analyzers. The cap comprises a skirt portion forming the side wall of the cap and having thread members on the interior surface of the side wall, the skirt portion having an open top with an inwardly extending rim. The cap also includes a top portion of a flexible elastomeric material sealed to the skirt portion through engagement with the inwardly extending rim and closing off the open top of the skirt portion. The flexible elastomeric material is selected to permit puncture by a needle or probe such that the hole formed by the puncture of the needle or probe permits passing of the needle or the probe therethrough and reseals after removal of the needle or probe. The top portion also includes an upwardly extending sealing surface near the periphery of the top portion. The sealing surface defines a cavity to the interior thereof which may be sealed against the external environment when the sealing surface contacts a planar surface. In an aspect of the invention there is provided a sample tube for use in automated sample accessioning equipment and automated clinical analyzers. The sample tube has generally cylindrical side wall with an open top and bottom and thread members provided on the exterior of the side wall near the top. The tube further has a cone- shaped sample holding divider located in the interior of the tube intermediate the top and bottom. The cone-shaped sample holding divider has an angular measurement to allow for a relatively small sample volume to be utilized such that a sample probe will be able to pick up the proper analysis volume from such relatively small sample volume. BRIEF DESCRIPTION OF THE DRAWINGS Preferred embodiments of the present invention are illustrated in the attached drawings in which: Figure 1 is a perspective view of a preferred embodiment of a biological specimen tube having a first embodiment of a cap according to the present invention; Figure 2 is a side elevation view of the tube and cap of Figure 1; Figure 3 is a side elevation view in cross- section of the cap of Figure 1; Figure 4 is a perspective view of a biological specimen tube having a second embodiment of a cap according to the present invention; Figure 5 is a side elevation view in cross- section of the cap and tube of Figure 4; Figure 6 is a side elevation view in cross- section of the cap of Figure 4 secured to the tube; Figure 7 is side elevation view in cross-section of an automated analyzer sample probe contacting the cap of Figure 4; and Figure 8 is a side elevation view in cross- section of an automated sample accessioning probe in contact with the cap of Figure 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first preferred embodiment of the closure cap of the present invention is illustrated in Figures 1 to 3 generally indicated by the numeral 10. The closure cap 10 is shown in association with a sample tube 12 for use in a automated clinical chemistry analyzer. Tube 12 is generally cylindrical in shape having side walls 14 and an open top 16 provided with thread members 18 on the exterior surface of the side wall 14 near the top. Tube 12 illustrated in the figures is for use with a sample analyzer utilizing microsampling where the sample probe may not travel the full depth of the tube 12. Thus, tube 12 is provided with a conical false bottom being a cone-shaped sample holding divider 20 located intermediate the top and bottom of the tube. The sample holding divider 20 is preferably cone-shaped to allow for a relatively small sample volume to be utilized such that the probe will be able to pick up the proper analysis volume from even such relatively small sample volumes. Preferably, the angle A between the side wall and the cone-shaped sample holding divider is about 30° as this angle has been found to maximize the use of very small sample volumes with such analyzers. Tube 12 may be of any suitable material which will not affect the sample so as to interfere with the analysis while being non-toxic such that the tube 12 may be disposed of by incineration. Preferably, the tube 12 is of a suitable thermoplastic material such as polypropylene, polyethylene or copolymers thereof. Cap 10 has a first skirt portion 22 forming the side wall of the cap as is shown in Figure 3. The skirt portion has thread members 24 on the interior surface of the side wall. Thread members 24 are complementary to the thread members 18 provided on the exterior of the tube 12. The skirt portion 22 is provided with an inwardly extending rim 26 defining a relatively open top. For increased ease of gripping, the skirt portion 22 on the exterior surface may be provided with knurls or serrations 28 which aid the user in gripping the cap 10 when placing the cap 10 on the tube 12 or removing the cap 10 from same. The closure cap 10 is also provided with a top portion 30 sealed to the skirt portion 22 through engagement with the inwardly extending rim 26 thereby closing off the open top of the skirt portion 22. Preferably to allow for ease of passage of a probe through the top portion 30 as will be described further below, the underside of the top portion may be provided with a dimple 32 such that the thickness of the top portion is reduced in the area through which the probe will pass. The closure cap 10 is also designed to be of low cost and constructed of non-toxic materials enabling the safe combustion without the generation of toxic by-products so that the sample tube and its contents may be destroyed by way of incineration upon completion of the testing. The skirt portion 22 is molded or extruded from a suitable polymeric material, preferably a olefinic thermoplastic such as suitably stiff forms of polypropylene or polyethylene or copolymers thereof to provide for the necessary mechanical support. More preferably, the skirt portion is molded or extruded from a polypropylene or polypropylene polyethylene blend. The top portion 30 is of a flexible elastomeric material, preferably a class 6 medical grade material which is acceptable for contact with biological specimens and will not alter the specimen. Such material is a thermoplastic elastomer, preferably a butyl-based material, more preferably, an elastomeric butyl-based olefinic thermoplastic and is fused to the inwardly extended rim 26 of the skirt portion 22 during the manufacturing process of the cap. The closure cap 10 is preferably produced by a two-step injection molding process. The process comprises the steps of providing an adjustable double-faced reversible mold for two shot injection molding of a two component closure, the mold having a first cavity portion on one face to receive the first injection for the skirt portion and an adjoining cavity portion on the reverse second face in the mold to receive simultaneous second injection for the top portion. The method involves injecting the polymer for the skirt portion, cooling the thus formed stiff skirt portion, resetting the mold by reversal and injecting the elastomeric material for the cap portion in fusing relation at interfaces with the first skirt portion, cooling the mold and ejecting the molded article. By using this method, it is possible to simultaneously inject the olefinic material for the skirt portion to the first mold cavity and the elastomeric material for the top portion of the second mold cavity to complete the molding of the closure cap without unloading or reloading the complete part. A second embodiment of the closure cap of the present invention particularly adapted for use with a closed sample accessioning system is illustrated in Figures 4 to 7 generally indicated by the numeral 40. The cap 40 has a skirt portion 42 having an inwardly extending rim 4 . Attached to the inwardly extending rim 44 is a top portion 46. The top portion 46 is provided with a upwardly extending sealing surface 48 to provide for a sealed cavity 50 when the cap is used with a closed sample accessioning system. Similar to the first embodiment, the cap 40 is used with a sample tube 52 having a cone-shaped sample holding divider 54 located intermediate the top and bottom. The exterior surface of the side wall 56 near the top is provided with thread members 58 which are complementary to thread members 60 located on the interior of the skirt portion 42 of the cap 40. The skirt portion 42 of the cap 40 may also be provided with a knurled surface for ease of gripping of the cap. Figure 7 illustrates the use of the cap 40 of the present invention with a automated clinical analyzer. As the transfer probe 62 contacts the top portion 46, the flexible elastomeric nature of the top portion 46 permits the stretching of the top portion 46 until such time as it reaches its break point at which point the probe 62 tears through the material of the top portion 46 and is passed through into the interior of the tube 52. As the tearing of the top material 46 occurs as it is being stretched by the probe 62 and owing to the nature of the material from which the top 46 is manufactured, as the probe 62 breaks through the top portion 46, the hole produced in the top portion 46seals around the walls of the probe 62. When the probe 62 is removed from the tube 52 through the top portion 46, the tear reseals against itself to provide for the sealing of the contents of the sample tube, both from exposure to the external atmosphere as well as reducing the possibility of leaking of the sample from the tube. Preferably to allow for ease of passage of the probe 62 through the top portion 46, the underside of the top portion 46 may be provided with a dimple 64 such that the thickness of the top portion 46 is reduced in the area through which the probe 62 will pass. Figure 8 illustrates the use of the closure cap 40 with a closed sample accessioning system. Typically, closed sample accessioning systems utilize a sample transfer probe 70 for transferring a sample from a blood collection tube to the sample tube 52. The probe 70 is generally provided with a cannula 72 having a first tip 74 for insertion into the blood collection tube, a second tip 76 for insertion into the sample tube 52 and a sealing plate 78 intermediate the tips 74 and 76 which seals against the sealing surface 48 to exclude any extraneous air from the sealed cavity 50. The sample is transferred from the blood collection tube into the sample tube 52 through application of a differential pressure either by creating an increased positive pressure in the blood collection tube or a decreased negative pressure in the sample tube 52. In this way, the specimen may be transferred from the blood collection tube to the sample tube 52 without the necessity of human intervention, thereby reducing the exposure of the operator to contact with the potentially infectious biological specimen. In order to aid in the stretching of the top portion 46 and the passage of the probe 70, the top portion 46 may be formed such that it has a slightly convex-shape as is illustrated in figures. This convex-shaping has advantages especially during the withdrawal of the probe 70 as it allows the probe to be withdrawn from the cap with reduced friction. In order to further reduce the friction associated with the withdrawal of the probe 70 to reduce the possibility of the probe 70 being disengaged from the analyzer or transfer machine, the elastomeric material from which the top portion is formed preferably incorporates therein, a small proportion of an agent which allows for reduced friction such as, for example, a polyterfluorethylene (PTF) or similar such material. Although various preferred embodiments of the present invention have been described herein in detail, it will be appreciated by those skilled in the art, that variations may be made thereto without departing from the spirit of the invention or the scope of the appended claims.

Claims: THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS: 1. A cap for sealing a biological sample tube for use in an automated analyzer, said cap comprising a skirt portion forming the side wall of the cap and having thread members on the interior surface of the side wall, said skirt portion having an open top with an inwardly extending rim, a top portion of a flexible elastomeric material sealed to the skirt portion through engagement with the inwardly extending rim and closing off the open top of the skirt portion, the flexible elastomeric material being selected to permit puncture by a needle or probe such that the hole formed by the puncture of the needle or probe permits passing of the needle or the probe therethrough and reseals after removal of the needle or probe. 2. A cap as claimed in claim 1 wherein the skirt portion is of an olefinic thermoplastic. 3. A cap as claimed in claim 2 wherein the olefinic thermoplastic is selected from the group consisting of polypropylene, polyethylene and copolymers thereof. 4. A cap as claimed is claim 1 wherein the flexible elastomer material is an elastomeric butyl-based olefinic thermoplastic. 5. A cap for sealing a biological sample tube for use in automated sample accessioning equipment and automated clinical analyzers,the cap comprising a skirt portion forming the side wall of the cap and having thread members on the interior surface of the side wall, the skirt portion having an open top with an inwardly extending rim, a top portion of a flexible elastomeric material sealed to the skirt portion through engagement with the inwardly extending rim and closing off the open top of the skirt portion, the flexible elastomeric material is selected to permit puncture by a needle or probe such that the hole formed by the puncture of the needle or probe permits passing of the needle or the probe therethrough and reseals after removal of the needle or probe, the top portion also including an upwardly extending sealing surface near the periphery of the top portion, the sealing surface defining a cavity to the interior thereof which may be sealed against the external environment when the sealing surface contacts a planar surface. 6. A cap as claimed in claim 5 wherein the skirt portion is of an olefinic thermoplastic. 7. A cap as claimed in claim 5 wherein the olefinic thermoplastic is selected from the group consisting of polypropylene, polyethylene and copolymers thereof. 8. A cap as claimed is claim 5 wherein the flexible elastomer material is an elastomeric butyl-based olefinic thermoplastic. 9. A sample tube for use in automated sample accessioning equipment and automated clinical analyzers,the sample tube comprising a generally cylindrical side wall with an open top and bottom and thread members provided on the exterior of the side wall near the top, a cone-shaped sample holding divider located in the interior of the tube intermediate the top and bottom,the cone-shaped sample holding divider having an angular measurement to allow for a relatively small sample volume to be utilized such that a sample probe of an automated clinical analyzers will be able to pick up the proper analysis volume from such relatively small sample volume. 10. A sample tube as claimed in claim 9 wherein the angular measurement of the cone-shaped sample holding divider is a 30° angle between the divider and the side wall.

Inventors: DAYKIN VICTOR, DAYKIN, VICTOR
Applicants: DAYKIN VICTOR, SAMCO SCIENT INC, DAYKIN, VICTOR, SAMCO SCIENTIFIC INC.
Application year: 1995
Main classification: B01L3
IPC codes: B01L3, B65D51