Patent Publication Number: US-6221027-B1

Title: Modular allergy testing apparatus

Description:
This application is a continuation-in-part of application Ser. No. 09/181,694, and now U.S. Pat. No. 6,077,229, filed Oct. 27, 1998, which was a continuation-in-part of application Ser. No. 08/955,370, filed Oct. 21, 1997, now U.S. Pat. No. 5,931,794 both of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to an allergy testing apparatus. 
     2. Description of the Prior Art 
     Allergy testing involves subjecting a patient to a wide variety of different allergens to determine which allergens cause allergic reactions in the patient. Such testing requires that the respective allergens be applied beneath the surface of the patient&#39;s skin. Typically, the patient is first screened by superficial scratches or punctures with allergens to test for severe reactions. If there are no severe reactions, the patient may be subjected to intradermnal tests with small bore needles. 
     Numerous different testing devices have been proposed for containing allergens to be applied to a patient. Examples include that shown in my earlier U.S. Pat. No. 4,237,906. There, I presented an individual tray which incorporated a top wall having a finite number of upwardly opening bores for telescopical receipt of individual allergen wells or vials. While having enjoyed substantial commercial success, this device, like many others proposed, had restricted flexibility in its ability to carry a wide number of wells or vials, depending on the number of different allergens to be applied in the procedure. 
     There is a need for modular testing trays which may be conveniently and releasably coupled together to provide the physician with the convenience of supporting a wide array of different allergens in a particular testing procedure. 
     SUMMARY OF THE INVENTION 
     The allergy testing apparatus of the present invention is characterized by a plurality of tray devices configured with bodies having coupling members along the sides thereof for releasably coupling together to thus support such trays arrayed together in a selected number to support various number of allergy wells or vials. 
     Other features and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the features of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a tray apparatus for holding allergen vials of the allergy testing apparatus of the present invention; 
     FIG. 2 is a perspective view of an allergen vial and applicator pick of the present invention: 
     FIG. 3 is a left end view, in enlarged scale, of a pair of tray apparatus, as shown in FIG. 1, assembled together showing the pick of FIG. 2, in enlarged scale; 
     FIG. 4 is a transverse sectional view, in enlarged scale, taken along line  4 — 4  of FIG. 1; 
     FIG. 5 is a transverse sectional view similar to FIG. 4 showing a pair of applicators inserted, taken along line  4 — 4  of FIG. 1; 
     FIG. 6 is a sectional plan view, in enlarged scale, taken along line  6 — 6  of FIG. 1; 
     FIG. 7 is a transverse sectional view, in enlarged scale, taken along line  7 — 7  of FIG. 5 showing the applicator being inserted into the vial while the vial is installed in the tray; 
     FIG. 8 is an end view, in enlarged scale, taken along line  8 — 8  of FIG. 7; 
     FIG. 9 is a side view, in enlarged scale, taken along line  9 — 9  of FIG. 7; 
     FIG. 10 is a sectional view similar to FIG. 7 but showing an optional vial with a threaded cap on the open mouth; 
     FIG. 11 is a sectional view similar to FIG. 7 showing a third embodiment of the vial; 
     FIG. 12 is a perspective view of an alternate embodiment of a tray apparatus embodying the present invention including vials; 
     FIG. 13 is a transverse sectional view, in enlarged scale, taken along line  13 — 13  of FIG. 12; 
     FIG. 14 is a longitudinal partial sectional view, in enlarged scale, taken along line  14 — 14  of FIG. 12; 
     FIG. 15 is a sectional view, in enlarged scale, showing a pair of trays, as depicted in FIG. 12 locked together; 
     FIG. 16 is a detail view taken from circle  16  of FIG. 15, shown in enlarged scale; 
     FIG. 17 is a detail view, taken from circle  17  of FIG. 14, shown in enlarged scale; 
     FIG. 18 is a longitudinal sectional view, taken along line  18 — 18  of FIG. 15, in enlarged scale; 
     FIG. 19 is a perspective view of an alternate embodiment of an applicator pick of the present invention; 
     FIG. 20 is a bottom plan view, shown in enlarged scale, of the applicator pick of FIG. 20; 
     FIG. 21 is a transverse sectional view, taken along line  21 — 21  in FIG. 20, shown in enlarged scale and inverted; 
     FIG. 22 is a sectional view, taken along line  22 — 22  of FIG. 20, in reduced scale, inverted, showing the pick installed in a well; 
     FIG. 23 is a view taken from circle  23  of FIG. 21, in enlarged scale; and 
     FIG. 24 is a bottom plan view taken from line  24 — 24  of FIG.  23 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In the following detailed description, like reference numerals will be used to refer to like or corresponding elements in the different figures of the drawings. The allergy testing apparatus of the present invention is embodied in an apparatus  20  (FIG. 5) for testing a patient&#39;s reaction to one or more allergens by applying allergen under the skin of a patient. More particularly, one aspect the invention includes, generally, a set of applicator picks  22  (FIG. 2) for applying allergen under the skin of the patient, a set of vials  24  (FIG. 2) which contain allergen specimens and into which the applicator picks fit, and a tray  26  (FIG. 1) which holds the vials and applicator picks during testing and storage. 
     The modular trays  26  are formed on their opposite sides with respective dovetail grooves  74  and dovetail tongue  72  which are configured to releasably couple the respective trays together in any one of a number of different combinations for supporting the vials  24  which receive the respective picks  22 . The picks may take numerous different forms. For example, the applicator pick incorporates a downwardly opening, integral, enlarged in diameter cup shaped plug  28  (FIGS. 2 and 7) which fits into the large open mouth  30  of the vial, thereby significantly reducing the number of parts required and allowing the vial to have a wider mouth opening for easy access. The applicator pick also includes improved long slender conically shaped tines  32  (FIG. 9) at its bottom which facilitate skin puncture and provide effective application of allergen. The applicator pick is versatilely designed with the tines being relatively long and narrow so as to be used in either the puncture or abrasion modes. The vial, being sealed at its top by the plug of the applicator pick, has a wide mouth opening for easy insertion of the applicator pick and is provided at its bottom with a sump  34 , referred to in FIG. 7, which ensures efficient use of substantially all of the expensive allergen. The tray into which the vials and applicator picks are held is configured such that two or more trays can be attached together, providing significantly enhanced flexibility and convenience to the technician at nominal cost, and is further provided with an optional clear plastic cover making storage more convenient. 
     The picks are configured centrally with the large diameter cup shaped plugs  28  for removable receipt in the respective vial mouths  30 , and have downwardly depending narrow stems  38  tapering to a diameter of about 0.16 inches at their bottoms and having a draft of 1°. Such stems are formed at their bottom extremities with a circular pattern of downwardly depending sharp, generally conically shaped, pointed tines  32  (FIG. 7) for, in the puncture test, penetrating under the epidermal layer of human skin. The tines serve primarily two functions. First, they provide a capillary action by increasing the surface area at the bottom of the stem, thereby loading the desired amount of allergen to the bottom of the applicator pick. This ensures that a proper dosage of allergen will be administered to the patient during any given application. Secondly, the tines are used to apply the allergen into the skin of the patient. Because they are of a selected length and sharply pointed, the tines can pierce the skin of the patient, thereby allowing the predetermined quantity of allergen suspended from the tip of the applicator pick to be deposited into the patient&#39;s skin for effective reaction in the patient. 
     The relatively long conical shape of the tines  32  (FIG. 9) is optimum for use in either the puncture or abrasion modes. This is because the conical shape provides a sharp point while minimizing the surface area of the tine. By minimizing the cross section of the tines, providing a circular shape and a selected length, the resistance to penetration of the tine by the patient&#39;s skin is reduced. The conical shape of the base portion of the tines also provides symmetrical structural rigidity about the entire radius of the tine, thereby uniformly resisting bending loads in any direction. The conical shape further provides a diameter which increases linearly from the tip portion toward the base of the respective tine. When the applicator pick is used in the abrasion mode, a force is exerted near the tip of the tine perpendicular with the longitudinal axis of the tine. This force causes a bending stress in the tine which increases linearly with distance from the tip of the tine. Having a diameter which increases linearly down the length of the tine causes the base portion of the tine to possess a stiffness which is directly proportional to the linearly increasing bending stress along the length of the tine. The tines terminate at the flat bottom wall  40  of the stem  38  (FIGS.  8  and  9 ), creating a stop to limit penetration of the tines. In this way each of the tines can easily be inserted into the patient&#39;s skin to a precise, predetermined depth. 
     Referring to FIG. 7, at the top of the narrow stem  38  of the applicator pick  22  and integral therewith, is formed a downwardly opening cup shaped plug  28  which is configured with an outer periphery to fit snugly into the top of the allergen vial  24 , securely sealing the allergen therein. The plug  28  consists of a circular horizontal disk  42  defining a top wall which is radially and concentrically disposed about the longitudinal axis of the shaft  38  and configured with a parametrical annular lip  44 . Extending downward from the outer edge of the disk is a cylindrical sleeve  46 . The sleeve is configured to form a free sliding fit within the collar  48  defining the mouth of the vial  24 . By constructing the cap integrally with the applicator pick, greater efficiency is achieved. Projecting above the cup shaped plug  28  is an upstanding handle  50  referred to in FIG.  2 . The handle is knurled or ribbed to allow easy gripping by the technician and is of sufficient diameter to make the applicator pick easy to manipulate. 
     With reference to FIG. 7, the lip  44  projects radially outwardly about the entire perimeter of the plug  28  to define a limit ring projecting radially outwardly beyond the cylindrical sleeve  48 . When the applicator pick and its cap are fully inserted into the vial  24 , the lip  44  nests on the top edge of the vial. In this way, the lip of the plug  28  acts as a stop, allowing the applicator to be easily and consistently inserted the proper distance into the vial  24 . By causing the applicator pick  22  to be inserted the proper distance into the vial, the tip of the applicator will be correctly placed in the bottom of the vial in a location which is optimal for collecting allergen but in which the tip will not contact the bottom wall of such vial. 
     In the preferred embodiment referred to in FIGS. 8 and 9, the applicator pick  22  can include from six to eight conical tines  32  but preferably includes eight tines  32  arranged in a circular pattern about the longitudinal axis of the applicator pick. In the center of the circular pattern, a downwardly opening concave allergen cup  52  (FIG. 8) is formed in the bottom wall  40  of the stem  38 . The tines cooperate to provide a capillary action causing allergen to adhere to the tip of the applicator pick  22  and the cup  52  further increases the capillary action. The tines  32  can be arranged in different patterns but in the preferred embodiment are disposed in a circular pattern about the central axis of the pick  22  in a pattern defining a circle having a 0.05 inch radius. The individual tines may be of various lengths such as from 0.050 to 0.1 inches, but are preferably about 0.31 inches in diameter at their respective bases and 0.07 inches long to facilitate penetration of the epidermis. Likewise, the cup  52  which can be of various depths is preferably configured with a radius of 0.03 inches and a depth of 0.01 inches. 
     Referring to FIG. 2, the vial  24  is cylindrically shaped and designed to fit within one of several wells  36  which are provided in a tray  26  as referred to in FIG.  1 . With reference to FIG. 7, the vial is formed with the upwardly opening collar  48  into which the sleeve  46  of the plug  28  of the applicator pick  22  tightly fits and has a generally curved, closed bottom. Extending radially outwardly from the top edge of the collar is a lip  56  which nests upon the top surface of the tray to act as a stop to support the vial. The collar  48  forms a large interior diameter defining a mouth  30  of 0.39 inches to facilitate ease of insertion of the applicator pick. The stem  38  of the applicator pick  22 , having a much smaller diameter than the inner diameter of the vial, can be easily inserted into the vial without requiring a high degree of manual dexterity on the part of the technician. 
     With continued reference to FIG. 7, the curved bowl shaped bottom wall of the vial  24  is provided with a downwardly depending small cylindrical sump  34  configured for complemental receipt of the bottom end of the pick  22  and into which the allergen collects. When the applicator pick  22  is fully inserted into the vial, the tip of the applicator will be disposed within the sump, thereby allowing allergen contained within the sump to adhere to the tip of the applicator. Use of the sump assures that substantially all of the expensive allergen will be effectively used and further assures that the last application from the vial will deliver the proper amount of allergen for delivery to the patient. 
     Referring again to FIG. 7, the exterior wall of the vial is provided with a frosted patch  60  of roughened texture which can be written on using a standard marker. This allows the technician to easily label the vial, further increasing convenience to the technician. 
     Referring to FIGS. 1 and 3, the tray  26  is generally in the form of a block shaped, open bottom plastic shell having a flat rectangular top wall  62 , opposite end walls  64  and elongated side walls  66 . Formed integral with the top wall are a plurality of upwardly opening cylindrical wells  36  for receiving the vials  24  of allergen. For the purpose of illustration, I show two rows of twelve wells  36 . However, in practice, I have found that a set of  20  wells  36  arranged in two rows of ten each provides for holding a sufficient number of vials for many applications. The wells extend only slightly downward from the top of the tray  26 . It will be appreciated that in the event it becomes necessary to change a vial the technician can push up on its bottom wall to dislodge it for removal. The tray is formed about its upper periphery with an outwardly and upwardly opening notch  68  (FIGS. 1,  4  and  5 ) for complemental receipt of the lower edge of a box-like transparent, downwardly opening lid, generally designated  70 . The tray and lid combine to provide, even with the wells filled with vials, the overall combination with a brick-like shape so such vial filled trays and lids may be easily stacked for storage and shipping. The trays can also be stacked and immobilized without the lid. 
     The tray  26  preferably includes releasable couplers on its opposite sides for coupling a selected number of such trays together in side by side relationship. In one embodiment such tray is formed in its opposite sides with a respective longitudinal coupling tongue  72  and a groove  74  to facilitate coupling two or more trays together to form a larger kit, generally designated  76 , shown in FIG.  3 . The tongue and groove are formed with a dovetail cross section for sliding, interlocking relationship. The respective tongues  72  are formed to project laterally from the vertically extending side walls of such trays to be configured with a tongue body projecting along a laterally extending axis and are configured at their respective distal extremities with enlarged cross sections to essentially form at their opposite sides respective keepers which are complementally received in the expanded cross section of the respective grooves  74  at their innermost extent to act as keepers to releasably hold such tongues held in the respective grooves. Referred to in FIG. 6, the grooves  74  are open on one end of the tray but stop short of the other end, thereby providing a groove end  76  to be engaged by a stop  78  formed at one end of the tongue  72  a short distance from the corresponding end wall of such tray, to limit sliding of such connecting tongue rail to maintain such trays aligned in flanking relationship. In this way, the technician can slide two trays together until the stop  78  of one tray reaches the groove end  76  in the second tray at which point the two trays will be perfectly adjacent and securely coupled to one another. The capability of coupling two or more trays together is an important advantage to the technician. If a patient requires use of only a small number of allergens, then the single tray can be used. However, if a patient requires testing of a greater number of allergens, the kit can be expanded to include all of the required allergens in one convenient kit for rapid and efficient use to apply all the allergen prescribed for the particular patient. 
     It will be appreciated by those skilled in the art that the trays  26  and lid  70  (FIG. 1) can be conveniently and inexpensively constructed of thermoplastic material. Likewise, the vial  24  and applicator pick  22  can be molded of thermoplastic using an injection molding process. 
     In operation, the trays  26 , vials  24 , applicators  22  and lid  70 , referred to in FIG. 5, may be shipped from the factory to the office of the doctor or laboratory technician. When a patient is to be treated with, for instance, approximately  24  or less allergens, only a single tray may need to be used. When a patient is to be tested for allergenic reaction, the allergenic extracts or allergens to be tested on the patient may be selected. Vials  24  may be inserted in the respective wells of the tray and filled with the selected allergen. To facilitate identification of the vials of allergen, the operator may label the allergen vials by writing an identification or code on the frosted patch  60  of each of the selected vials using a pen or other standard writing implement. 
     In the event the technician elects to apply a number of allergens greater than that for the number of wells in a particular tray  26 , it is convenient to merely couple two or more trays together, as shown in FIG. 3, to provide the desired number of vials carried in the various wells  36 . In this fashion, assuming the technician sought to administer, for instance, 38 different allergens, two trays would be coupled together by sliding the tongue  72  of one tray into the open end of the dovetail groove  74  of the adjacent tray to the extent permitted by groove end  76  and stop  78  (FIG.6) thus assuring longitudinal alignment of the respective trays to provide a pair of modules having a total capacity of, for instance, 44 vials. Assuming the technician proceeds with the  38  different vials selected, the wells of one full tray  26  may be filled with respective vials and 16 wells of the second tray may likewise be filled with vials. The vials will be typically prefilled with allergen before the procedure is commenced so that the technician can quickly and efficiently remove the picks from the respective vials  24  and administer the allergen as described hereinabove to thereby provide for treating the patient in the minimum amount of time and thus minimize the period of time to which the patent is subject to the trauma and stress associated with any concern which may be raised about the overall procedure. 
     As the technician then treats the patient, the picks  22  (FIG. 3) may be withdrawn in progression from the respective vials  24 . As the respective stems  38  (FIG. 2) are withdrawn from the allergens in the respective vials, the capillary action of the allergens will cause a selected quantity of such allergens to adhere to the surfaces of the respective tines  32  (FIG. 9) and bottom wall  40  of the stem  38  and within the confines of the allergen cup  52  (FIGS.  8  and  9 ). In this regard, it will be apparent to those skilled in the art that allergens have generally the same viscosity and, within reason, the same general capillary characteristics, such that the desired quantity of allergen will remain adhered to the tip of the stem as it is removed from the vial. The technician may then apply the allergen beneath the patient&#39;s skin by pressing the end of the applicator pick against the patient&#39;s skin using either the puncture or abrasion techniques. 
     It will be appreciated that this option of utilizing the individual pick for administration of the allergen by either a puncture method or an abrading or scarifying method is of great advantage. Referring to FIGS. 7,  8 , and  9 , for the puncture method the technician will merely move the pick  22  over the skin with the residual allergen fluid adhered by capillary action to the surfaces of the tines  32 , bottom wall  40  and cup  52  and pressing the stem inwardly to cause the points of such tines to puncture the skin in a circular pattern so that further inward pressing will serve to introduce the quantity of allergen held thereon some 0.07 inches beneath the exterior surface of the patient&#39;s skin to penetrate beneath the relatively tough epidermis. Since the quantity of allergen and maximum depth of the puncture is already predetermined by the length of the tines, the depth of penetration and amount of allergen introduced is limited. Consequently, this administration can be performed by a technician with a minimal amount of experience and understanding of the medical ramifications thereof. It will be appreciated that the multiple long thin tines will serve to not only cooperate together in carrying the desired quantity of antigen but will puncture small diameter thin puncture holes to be effective in introducing the necessary quantity of antigen, while provoking only a slight skin irritation in the patient, far less than would be the case for one or more larger diameter prongs or tines. In the event the patient proves to have unusually tough skin or skin otherwise not susceptible to easy puncture, there remains a ready option. 
     The technician may resort to what is known as the “scratch test” where the skin is typically abraded by a scarifying device. The applicator of the present invention can be utilized by even the most inexperienced technician. In this approach, the points of the tines  32  (FIG. 9) are only slightly penetrated into the skin surface and the technician may turn the handle  50  (FIG. 2) to rotate such stem about its longitudinal axis causing the points to scratch the skin surface, making small cuts therein for positive introduction of the allergen carried on such tines. Once the patient is screened by either the above described puncture or scratch technique without a reaction, an injection technique may be carried out with a hypodermic needle or the like to inject larger quantities of allergen beneath the skin. 
     The used pick  22  referred to in FIG. 2 will then be discarded and a new pick selected for each of the vials of the tray and inserted into the vial at the end of the test to act as a stopper to maintain the biological cleanliness of the allergen until the next application for the subject patient or subsequent patient. It will be appreciated that insertion of the applicators in the wide mouth  30  of the vials is facilitated by the relatively small diameter of the stems  38  which serve to essentially lead the applicator into such vial as it is lowered, as shown in FIG. 7, to thus maintain the pick somewhat centered in the vial so as to tend to register the skirt  46  of the plug  28  concentrically with the mouth  30  so that the technician may quickly and positively register such plug into sealing position for positive sealing thereof. The procedure will then be repeated for each of the picks in the vials positioned in the tray  26  (FIG.  5 ). When all of the picks have been discarded, the technician will know that this particular treatment of the patient has been completed. 
     Before the tray is stored, the technician inserts new sterile picks  22  (FIG. 2) into the respective vials  24  so that the respective mouths  30  of the vials will be closed by the respective plugs  28  of the new picks  22 . For storage, the clear plastic cover  70  (FIG. 5) may be placed onto the tray to allow the assembled allergy testing kits  20  to be easily stacked, significantly saving storage space. 
     In an alternate embodiment, shown in FIG. 10, a vial  80  is provided, substantially the same as the vial referred to in FIGS. 1-7 but including a rim or skirt  82  projecting upwardly above the lip  84  and threaded on its exterior for engagement with the cylindrical wall of a closure cap, generally designated  86 . The cap is conveniently constructed of plastic and formed with a cylindrical stub wall  88  formed on its interior with mating threads. An annular compression seal  90  may be frictionally held within the cap  86  for sealing against the annular top edge of the vial  80 . 
     In operation, it will be appreciated that the vial  80  of FIG. 10 may be loaded with an allergen and the cap  86  screwed thereonto in tight sealing relationship so that the pre-sterilized vial may be maneuvered about, stored, or shipped with its allergen contained therein and the cap in place. When the technician is then to gain access to the vial for utilizing the allergen, the cap  86  may be unscrewed and discarded. The pick  22  (FIG. 7) may then be inserted in place to move the plug  28  into sealing relationship with the mouth of the vial. 
     In another alternate embodiment, referred to in FIG. 11, a vial  92  is provided which is similar to the vial  24  referred to in FIGS. 1-7 except that it projects vertically above a nesting lip  94  to define a cylindrical hand grasp rim  96 . 
     In use, this embodiment allows convenient removal and interchange of vials  92  within a tray  26  referred to in broken sectional view in FIG.  11 . If the technician desires to change the vials in a tray to accommodate the needs of a patient, the vial can be easily removed by grasping the rim  96  between the technician&#39;s thumb and index finger. This embodiment obviates the need to force the vial up from beneath, greatly increasing convenience to the technician. 
     The embodiment of the allergen applicator shown in FIGS. 12-24 is similar to that shown in FIGS. 1-11 and includes, generally, a well strip  98  configured for receipt within the top of a tray  100  (FIG.  12 ). The well strip includes a set of upwardly opening wells, generally referred to as  102  (FIG.  12 ), which are configured at their tops for receipt of a set of applicators, generally referred to as  104  (FIG.  19 ). 
     With reference to FIG. 12, the well strip  98  is constructed of plastic and is in the form of a flat rectangular plate  101  about 0.04 inches thick, integrally formed with the wells  102 . I have found that in use, a well strip having 20 wells in two rows of 10 each provides a preferable configuration, providing both a sufficient number of wells for most applications and a manageable size which can be easily manipulated. However, for this example, I show two rows of 8 for a total of 16. The well strip is configured at the comers of one end with orientation tabs  106  in the form of chamfers designed for mating relationship within the tray  100 , while the opposite end is formed with rounded comers  108  (FIG.  1 ). 
     With reference to FIG. 22, the open tops of the wells  102  extend beyond the top of the well strip to form stub walls defining sealing lips  110 . The wells pass through the plane of the strip forming cylindrical collars  112  and terminate in rounded bottom walls  114 . The bottoms of the wells terminate in cylindrical sumps  116  which serve to collect allergen when little allergen remains in the vial, thus assuring efficient use of substantially all of the allergen. 
     With reference to FIG. 12, the tray  100  is also constructed of plastic and is generally block shaped and formed with a rectangular top wall  118  with side walls  120  extending downwardly from the edges thereof. The well strip  98  fits into a rectangular recess  122  (FIG. 15 and 16) formed in the top of the tray. The recess is provided at one end with chamfered corners  124  (FIG. 12) and at its opposite end with rounded comers  126  formed to mate with respective oppositely disposed chamfered orientation tabs  106  and rounded corners  108 , respectively, formed in either end of the well strip, thereby ensuring the correct orientation of the well strip within the tray. The top of the tray is further provided at each end with a finger slot  128  (FIGS.  12  and  17 )) in the form of a notch having a depth greater than the thickness of the well strip, extending from the end of the tray to a point beyond the adjacent end of the recess. The finger slots provide access to respective finger tabs  129  formed by the respective opposite ends of the strip to facilitate convenient removal of the well strip by simply placing a fingernail or implement within each slot to reach beneath the respective tabs  129  to lift the strip out of the tray. 
     With reference to FIG. 16 the recess  122  formed in the top  118  of the tray  100  of the alternate embodiment includes well receiving holes  130  through which the wells  102  fit when the well strip  98  is installed in the tray. The wells have beveled upper edges  132  which assist installation of the well strip by deflecting the wells into proper position in the well holes when the well strip is slightly misaligned during installation. 
     With continued reference to FIGS.  15  and ts, a pair of vertical rails  134  formed on one side of the tray, configured for mating relationship with a pair of channel housings  135  defining channel tracks  136  (FIG. 13) on the opposite side of the tray, allow one tray to adjoin with another by sliding the rails of one tray vertically into the channels of the other tray. The rails and channels mate in dove-tail fashion and the channel housing is provided with a closed upper end  138  (FIG. 13) which engages the upper end  140  of the rail providing a stop to limit further movement of the rail within the channel when the trays are flush with one another as illustrated in FIG.  15 . 
     With reference to FIG. 19, an alternate embodiment of the applicator pick generally referred to as  104  includes a downward depending tapered stem  142  terminating at a flat bottom  144  (FIG.  21 ). A set of generally conical thin tines  146  having slender pyramidal tips  148  extend from the bottom of the stem in a symmetrical, circular pattern. The pyramidal shape at the tip of each tine provides flat upwardly and outwardly diverging facets  150  (FIG. 23 and 24) which meet to form edges  152  to promote cutting of the patient&#39;s skin during initial puncture allowing the tip of the tine to more easily pierce the patient&#39;s skin. The pyramidal shape also facilitates manufacture of the applicator by aiding in removal of the tine from a mold. While the preferred embodiment of the pyramidal tip includes four facets, other pyramidal shapes having at least three facets can similarly provide the advantageous cutting effect. This pyramidal tip smoothly joins a frusto conical remainder of the tine, which constitutes the majority of the length of the tine. Once the tips of the tines have initially pierced the patient&#39;s skin, the frusto conical shape of the remainder of the tine optimally facilitates further insertion of the tine by minimizing the surface area in contact with the patient&#39;s skin and correspondingly minimizing frictional resistance to further insertion of the pick. The frusto conical configuration of the remainder of the tine provides uniform resistance to bending stresses throughout the majority of the length of the tine, increasing at the portions of the tine closest to the base where the bending stresses on the tine will be greatest when the pick is used in the abrasion mode. 
     While several configurations of tines could provide satisfactory results, I have found that eight tines  146 , disposed in a circular pattern about the bottom of the stem, provide a preferable configuration for use in both the puncture and abrasion modes. Disposing the tines in a circular pattern allows the tines to abrade the patient&#39;s skin in a circular pattern when the technician twists the applicator about its axis. While the tines could be of various lengths and widths, I have found that tines having an overall length of 0.070 inches from base to tip and a width of 0.031 inches at the base provide advantageous sharpness as well as bending resistance and moldability. The pyramidal tip of such a tine should make up the last 0.030 inches at the tip of the tine. I have found that the picks may be injection molded from polyacetal sold under the trademark CELCON® or DELRIN®. 
     I have found that such tines should have an overall length greater than 0.05 inches to, in the puncture test, reach under the epidermis but not greater than about 0.1 inches to avoid excessively deep penetration which would add to the patient&#39;s trauma. The base of the stems should be at least 0.020 inches wide to afford the necessary structural integrity but not more than about 0.045 so as to avoid an unduly large cross section puncture and consequent discomfort. 
     With reference to FIG. 21, the tines  146  surround a dome shaped, allergen cup  156  formed at the center of the flat bottom  144  of the stem  142 . The allergen cup opens downwardly, having a depth of 0.01 inches and a radius of 0.065 inches. The allergen cup serves to increase the surface tension at the bottom of the stem, creating a capillary effect in order to cooperate with the surface of the tines to hold a predetermined quantity of allergen upon withdrawal of the applicator from a well  102  (FIG. 22) for application to a patient. As will be appreciated by those skilled in the art, for the screening test, whether it be by the scratch or puncture technique, the quantity of allergen should be about 0.1 cc or about {fraction (1/20)}th of that utilized in an intradermal technique. I have found that with this combination, the pick of the invention is effective to repeatedly carry about 0.1 cc of antigen from the respective wells. 
     With reference to FIG. 19, the applicator pick  104  includes a top  158  in the form of a disk extending radially from the upper portion of the stem  142  of the pick. The radial extremity of the disk turns downward to form a circumferential flange  160  (FIG. 22) for sealing engagement with the sealing lip  110  at the top of the well  102  in which it is inserted. Although described for use with the well (FIG.  23 ), it will be appreciated that this pick embodiment  104  could also be used with the vial  24  (FIG. 2) of previously described embodiment. 
     A cruciform collar  162  (FIG. 19) extends downward from the disk shaped top in the form of four vertical flanges  164  (FIG. 20) projecting radially from the stem at right angles to one another and dimensioned radially so as to fit slidingly and freely within the cylindrical collar  112  of the well  102  (FIG.  22 ). Such collar may, in practice, be constructed in the form of a cylindrical plug body loosely fit in a well  102 . 
     Referring to FIGS. 8 and 22, a narrow cylindrical handle  166  extends upward from the disk shaped top  158 , coaxial with the stem  142  so as to be conveniently gripped between the thumb and index finger, not shown, of the technician during use. The handle is supported by a cylindrical neck of relatively smaller diameter than the handle, extending a short distance from the top  158 . The neck flares radially outward at its top to form a shoulder  122  serving as the bottom of the handle portion. The shoulder facilitates removal of the pick  104  from the well  102  by creating a surface against which to grip when pulling upward on the handle. Knuris or ribs  168  formed in the surface of the handle further facilitate gripping the handle during use. 
     As will be appreciated by those skilled in the art, the tray  100 , well strip  98  and applicator pick  104  can be easily and inexpensively constructed of injection molded thermoplastic. The stem  142  of the pick is formed with a 1° draft which facilitates removal of the pick from a mold, not shown. The tray and well strip can also be formed by vacuum molding. 
     To use well strip  98 , the physician may first install the well strip into the rectangular recess  122  of the tray  100 , aligning the chamfered orientation tabs  106  of the well strip  98  with the chamfered corners  124  of the recess  122  to assure correct alignment, and then fill the wells  102  with the desired allergen. The technician may then install the applicator picks  104  (FIG. 20) into the tops of the wells to seal the allergen therein. The collar  162  will guide and hold the applicator pick in place within the well. 
     Should the physician wish to use a different set of allergens, he or she can simply remove the existing well strip  98  by lifting the tray from the finger tabs  129  to discard the entire strip and picks. The technician may then replace the well strip with another well strip previously loaded with the desired allergen. If more than 16 allergens are to be tested, the technician has the option of creating a larger test kit by sliding the rails  134  of one tray vertically into the channels  136  of another tray until the upper ends of the rails  140  stop against the closed upper ends of the vertical channel  136 , thereby locking the two trays together. 
     When a physician undertakes to screen a patient, he or she may withdraw the individual applicator pick  104  from the bath of antigen in the respective well  102  causing the tines  146  and cup  156  to carry therewith about 0.1 cc of antigen. The applicator pick  104  can be either pressed directly down onto the patient&#39;s skin for use in the puncture mode to cause the sharp thin pyramidal points  148  to knife through the epidermal layer peeling the skin back to open the way for the conical remaining length of such tines  146 . The tines  146  will thus serve to carry a great majority of the 0.1 cc of antigen thereon and cooperate with the cup  156  so that during puncture or scratching effective application of the antigen along the long slender surface will be accessed. The technician can press downwardly without concern over an excessively deep penetration since the tines themselves are only 0.070 inches long to reach just under the epidermis. Should the patient have unusually tough or thick skin, the technician can withdraw the tines so just the tip section remains in the outer skin layer. Then by rotating the pick about its own axis, the tine tip will scratch the skin depositing the particular allergen in the scratches to test for a reaction. For those allergens where there was symptoms of an extraordinary reaction, the technician might turn the patient over to the experienced medical doctor for an injection test where a hypodermic needle is employed to inject allergen under the skin to introduce a larger quantity of allergen. The physician may then examine the skin for symptoms of a reaction to form an opinion as to whether there might be any overaction should he or she proceed with the intradermal test. 
     From the forgoing it will be appreciated that the invention provides significant cost savings while including features which greatly enhance convenience and versatility. The tray apparatus of the present invention provides an economical and convenient means for coupling a selected number of trays together so as to allow flexibility for the physician to preload vials or wells with a particular number of allergens, depending on the allergies for which the patient is to be tested. While several particular forms of the invention have been illustrated and described, it will also be apparent that various modifications can be made without departing from the spirit and scope of the invention.