Pipette tip

ES 2 397 544 T3

DESCRIPTION

Pipette tip.

BACKGROUND OF THE INVENTION

Field of the invention

The present invention relates to pipette tips as such are defined in the appended claims.

Description of the prior art

Figures 1, 2 and 3 are various views of a conventional pipette 2 incorporated into the VetTest veterinary blood analyzer^® available from IDEXX Laboratories, Inc. of Westbrook, Maine. The conventional pipette comprises a main body 4 having a central hole 6 extending axially therethrough and a dispensing tip 8. The dosing tip 8, which has one end of the distal tip 9, an opposite proximal end 11 and a side wall 13, comprises a circular opening 10 made in the lower surface of the distal end 9 which is directed towards the central hole 6 of the body. main pipette 4. A fluid is dispensed from the central hole 6 out of the circular opening 10 by pneumatic force. The structure and operation of such a pipette is more fully described in US Patent Nos. 5,089,229; 5,250,262; and 5,336,467, each in the name of Thomas Heidt et al., the disclosures of which are incorporated herein by reference.

The VetTest® system is used to apply a body fluid, eg, urine, serum and / or plasma onto test slides that have a chemical or biological reagent on the surface of the slide. The conventional pipette 2 automatically distributes certain amounts of fluid over a plurality of test slides, each of which may have a different reagent coating. A minor concern with the VetTest® is that occasionally zone failure occurs (i.e., misapplication of serum / plasma on a slide). Such zone failure is rare and can occur as a result of incompatible fluid volumes or no fluid being deposited on the slides. Zone failure has been considered, at least partially, with respect to the design of the pipette tip and the material (ie, polypropylene) from which the dispensing tip 8 of the pipette is preferably made.

As a specific amount of fluid is dispensed from the dispensing tip 8 of the conventional pipette 2, fluid dynamics causes a substantially spherical droplet to form in the circular opening 10. As the droplet approaches the target volume, pipette 2 is lowered onto the slide until the droplet comes into contact with the chemically coated part of the film on the slide, thereby withdrawing it from the dispensing tip 8 of the slide. pipette 2 due to capillary action, surface tension and droplet gravitational force. Unfortunately, the ability to control the exact amount of fluid dispensed onto a test slide is limited, as small amounts of the droplet are occasionally drawn onto the outer surface of the end of the distal tip 9 of the dispensing tip 8, which are It is at least in part due to the predisposition of the polypropylene pipette tip 8 to wetting or attracting fluid to the outer surface of the pipette tip. Wetting of the outer surface may cause an imprecise volumetric amount of fluid to deposit or no fluid to deposit on the test slide.

Document EP 0 383 563 discloses the geometric shape of a nozzle for controlling the dispensing of liquid.

OBJECTIVES AND SUMMARY OF THE INVENTION

It is an object of the present invention to provide a pipette that can dispense precise amounts of fluid.

It is a further object of the present invention to provide a pipette that can dispense precise amounts of fluid onto a test slide provided with a reagent or into a vial containing a chemical reagent.

It is a still further object of the present invention to provide a pipette that eliminates or at least minimizes the inappropriate volume of fluid sample dispensing.

The pipette tip of the present invention is defined in claim 1. Preferred embodiments are described in the dependent claims. The lower surface of the pipette tip is made with one or more grooves arranged concentrically or spirally around the central opening. The grooves can be of any dimension, for example V-shaped or rectangular in cross-section, and prevent the sample fluid droplet from flowing along the bottom surface and thus moving to the outer surface. of

ES 2 397 544 T3 the side wall of the pipette tip, thereby reducing the inappropriate volume of dispensing the sample fluid onto the test slide with a chemical reagent or into the vial containing a chemical reagent. Clearly, this added fluid control may have applications outside of the field of locating the chemical reagent slide, such as, for example, wet and dry chemicals, microbiology applications, including genetic testing, commercial processes, and the like.

These and other objects, features and advantages of the present invention will become apparent from the following detailed description of illustrative embodiments thereof, which should be read with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a bottom view of the tip of a conventional fluid dispensing pipette tip used in a chemical analyzer.

Figure 2 is a perspective view of a conventional pipette used to deposit serum or blood plasma onto a test slide with a chemical reagent or into a vial containing a chemical reagent.

Figure 3 is a detailed longitudinal cross-sectional view of the distal end of the pipette shown in Figure 2.

Figure 3A is a bottom view of a pipette tip of the present invention having a single groove.

Figure 3B is a bottom view of an alternative pipette tip of the present invention having an enlarged bottom surface.

Figure 4 is a longitudinal cross-sectional view of the tip portion of a fluid dispensing pipette constructed in accordance with an alternative embodiment of the present invention.

Figure 5 is a bottom view of the tip of the pipette of the present invention depicted in Figure 4.

Figure 6 is a longitudinal cross-sectional view of the tip portion of a fluid dispensing pipette constructed in accordance with an alternate embodiment of the present invention.

Figure 7 is a bottom view of the tip of the pipette of the present invention depicted in Figure 6.

Figure 8 is a longitudinal cross-sectional view of the tip portion of a fluid dispensing pipette constructed in accordance with an alternate embodiment of the present invention.

Figure 9 is a bottom view of the tip of the pipette of the present invention shown in Figure 8.

Figure 10 is a longitudinal cross-sectional view of the tip portion of a fluid dispensing pipette constructed in accordance with an alternate embodiment of the present invention.

Figure 11 is a bottom view of the tip of the pipette of the present invention depicted in Figure 10.

Figure 12 is a longitudinal cross-sectional view of the tip portion of a fluid dispensing pipette constructed in accordance with an alternate embodiment of the present invention.

Figure 13 is a bottom view of the tip of the pipette of the present invention depicted in Figure 12.

Figure 14 is a longitudinal cross-sectional view of the tip portion of a fluid dispensing pipette constructed in accordance with an alternate embodiment of the present invention.

Figure 15 is a bottom view of the tip of the pipette of the present invention depicted in Figure 14.

Figure 16 is a longitudinal cross-sectional view of the tip portion of a fluid dispensing pipette constructed in accordance with an alternate embodiment of the present invention.

Figure 17 is a bottom view of the tip of the pipette of the present invention depicted in Figure 16.

Figure 18 is a longitudinal cross-sectional view of the tip portion of a fluid dispensing pipette constructed in accordance with an alternate embodiment of the present invention.

Figure 19 is a bottom view of the tip of the pipette of the present invention depicted in Figure 18.

ES 2 397 544 T3

Figure 20 is a longitudinal cross-sectional view of the tip portion of a fluid dispensing pipette constructed in accordance with an alternate embodiment of the present invention.

Figure 21 is a bottom view of the tip of the pipette of the present invention shown in Figure 20.

Figure 22 is a longitudinal cross-sectional view of the tip portion of a fluid dispensing pipette constructed in accordance with an alternate embodiment of the present invention.

Figure 23 is a bottom view of the tip of the pipette of the present invention shown in Figure 22.

Figure 24 is a longitudinal cross-sectional view of the tip portion of a fluid dispensing pipette constructed in accordance with an alternate embodiment of the present invention.

Figure 25 is a bottom view of the tip of the pipette of the present invention depicted in Figure 24.

Figure 26 is a longitudinal cross-sectional view of the tip portion of a fluid dispensing pipette constructed in accordance with an alternate embodiment of the present invention.

Figure 27 is a bottom view of the tip of the pipette of the present invention depicted in Figure 26.

Figure 28 is a longitudinal cross-sectional view of the tip portion of a fluid dispensing pipette constructed in accordance with an alternate embodiment of the present invention.

Figure 29 is a bottom view of the tip of the pipette of the present invention depicted in Figure 28.

Figure 30 is a longitudinal cross-sectional view of the tip portion of a fluid dispensing pipette constructed in accordance with an alternate embodiment of the present invention.

Figure 31 is a bottom view of the tip of the pipette of the present invention shown in Figure 30.

DETAILED DESCRIPTION OF THE PREFERRED FORMS OF EMBODIMENT

The present invention is an improvement over the conventional pipette tip 8 used in the VetTest® veterinary blood analyzer described above and in patents to Heidt et al. mentioned above (US Patent Nos. 5,089,229; 5,250,262; and 5,336,467).

Referring to Figures 3A to 31, the present invention comprises a disposable pipette tip 14 that is disposed at the end of a conventional pipette 2. The pipette tip 14 has a main body comprising an upper end 18, an end opposite lower 20, a side wall 16 having an outer surface and extending between the upper and lower ends 18, 20, and a central hole 22 extending axially therethrough. The tip 14 converges radially inward from the upper end 18 towards the lower end 20, the lower end 20 having a narrower diameter than the upper end 18. The lower end 20 has a lower surface 23 constituted by a central opening 24 which communicates with axial hole 22 to allow sample fluid to pass through. Upper end 18, as opposed to lower end 20, may comprise a plurality of radially outwardly extending support fins (not shown), such as in the conventional pipette tip described in patents issued to Heidt et al.

In accordance with the present invention, the lower surface 23 of the pipette tip 14 comprises one or more grooves or cuts made therein and may be enlarged. The slots or cuts can be made by molding, milling, punching, cutting, or other similar means. The grooves can vary in depth, shape and dimension, and can be concentric with the central opening 24 on the bottom surface 23 or can be arranged in a spiral on the bottom surface 23. Furthermore, the grooves may be continuous circumferentially around central aperture 24, or they may be intermittent arcuate segments circumferentially spaced from one another around central aperture 24. Likewise, the lower surface of the pipette may be substantially flat (as shown in Figures 3A to 29) or it may have a convex profile (as shown in Figures 30 to 31) with one or more grooves or other means. intended to prevent radial flow of fluid from the central opening 24.

In Figure 3A, a pipette tip 14 preferably has the same inside / outside dimensions as prior art tips (see, for example, Figure 1, with an aperture diameter of approximately 0.030 inches and an outer diameter of the tip). tip about 0.0685 inch), but also comprises slot 28. The comparative pipette tip 14 of Figure 3B has no groove but has an enlarged outer diameter to inhibit, prevent, or otherwise reduce fluid flow between the opening 24 and the outside of the lower end 20. In a preferred embodiment, the inside diameter of aperture 24 of Figure 3B is about 0.030 inches (0.762 mm), while the diameter of the outer tip is between about 0.069 inches (1.75 mm) and about 0.115 inches (2.92 mm).

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Referring again to Figures 4 and 5, the lower surface 23 of the lower end 20 of the pipette tip, according to an embodiment of the present invention, may have one or more triangular or V-shaped grooves 28 (when seen in cross section), similarly sized, cut into bottom surface 23, arranged concentrically (or arranged spirally) around central aperture 24. The triangular slot (s) 28 may have two opposing side walls 30 spaced at an angle of preferably about sixty-five (65) degrees that diverge from the apex of the slot to form an opening 32 of preferably about 0.0080 inches (0.203 mm) on the bottom surface 23. Triangular groove 28 can be cut into bottom surface 23 to various depths, but is preferably cut to a depth of about 0.0063 inches (0.16 mm). If a slot 28 is used, as shown in Figures 4 and 5, the radial inner edge of slot opening 32 made in bottom surface 23 preferably has a radius of about 0.0355 inches (0.902 mm) from the bottom. center of pipette tip 14.

In another embodiment of the present invention, as illustrated in Figures 6 and 7, the lower surface 23 of the lower end 20 of the pipette tip may have one or more square-shaped grooves 34 (when viewed in section transverse) cut into the bottom surface 23, arranged concentrically (or arranged in a spiral) around the central opening 24. The square groove (s) 34 may comprise a recessed top wall 36, two side walls 38, and an opening 40 in the bottom surface 23. The two side walls 38 are preferably about 0.10 apart. 0080 inches (0.203 mm). As in the previous embodiment of the present invention depicted in Figures 4 and 5, the square groove (s) 34 can be cut into the bottom surface 23 at various depths, but are cut preferably to a depth of about 0.0060 inches (0.152 mm). If a groove 34 is used, as shown in Figures 6 and 7, the radial inner edge of the groove opening 40 made in the bottom surface 23 preferably has a radius of about 0.0355 inches (0.902 mm) from the center of pipette tip 14.

In yet another embodiment of the present invention, as illustrated in Figures 8 and 9, the lower surface 23 may have a plurality of triangular or V-shaped grooves with different dimensions (preferably two), cut into the surface. bottom 23 of the pipette tip, arranged concentrically around the central opening 24. An outer triangular radial slot 42 may have two opposing sidewalls 44 spaced at an angle of preferably about sixty-five (65) degrees diverging from the apex of slot 42 to form an opening 46 of preferably about 0.0076 inches (0.193 mm). ) on the lower surface 23. The outer triangular groove 42 can be cut into the bottom surface 23 to various depths, but is preferably cut to a depth of about 0.0060 inches (0.152 mm). An inner triangular radial groove 48 may have two opposing side walls 50 spaced at an angle of preferably about sixty-five (65) degrees diverging from the apex of groove 48 to form an opening 52 of preferably about 0.0062 inches (0.157 mm). ) on the lower surface 23. The inner triangular groove 48 can be cut into the bottom surface 23 to various depths, but is preferably cut to a depth of about 0.0048 inches (0.122 mm). The radial inner edge of the outer slot opening 46 made in the bottom surface 23 preferably has a radius of about 0.0361 inches (0.917 mm) from the center of the pipette tip 14, and the radial inner edge of the Inner groove 52 made in bottom surface 23 preferably has a radius of about 0.0232 inches (0.589 mm), also determined from the center of pipette tip 14.

In each of the embodiments of the present invention described above and represented in Figures 4 to 9, the lower end 20 and the lower surface 23 thereof are enlarged to accommodate the slot (s), and preferably have an outer diameter of approximately 0.0970 inches (2.46 mm). The central opening 24 preferably has a diameter of about 0.0310 inches (0.787 mm). However, as shown in FIG. 3A, enlargement of the lower surface 23 is not required.

A further embodiment of the present invention is illustrated in Figures 10 and 11 of the drawings. In such an embodiment, the bottom surface 23 comprises one or more triangular or V-shaped grooves 28 (when viewed in cross section), similarly sized, made in the bottom surface 23 and arranged concentrically around the central opening. 24. Said embodiment is similar to that shown in Figures 4 and 5, except that the dimensions of the lower surface 23, the central opening 24 and the V-shaped grooves are different.

More specifically the triangular slot (s) 28 may have two opposite sidewalls 30 spaced apart at an angle of preferably about ninety (90) degrees that diverge from the vertex of the slot to form an opening 32 of preferably about 0.0100 inches (0.254 mm) on bottom surface 23. Triangular groove 28 can be cut into bottom surface 23 to a depth of about 0.0050 inches (0.127 mm).

In the embodiment of the present invention illustrated in Figures 10 and 11 of the drawings, the radius of the

ES 2 397 544 T3 tip opening 24 is preferably about 0.0150 inches (0.381 mm); and the outer periphery of bottom surface 23 has a radius of approximately 0.0525 inches (1.33 mm). The inner edge of the innermost slot opening 32 preferably has a radius of about 0.0225 inches (0.527 mm) and the inner edge of the outermost slot opening 32 preferably has a radius of about 0.0350 inches ( 0.889 mm).

Figures 12 and 13 illustrate another embodiment of the pipette tip of the present invention that is similar in many respects to the embodiment of the pipette tip depicted in Figures 10 and 11. However, the dimensions of the The embodiment shown in Figures 12 and 13 differ from the embodiment shown in Figures 10 and 11.

More specifically, and referring to Figures 12 and 13 of the drawings, the pipette tip is preferably made with a central opening 24 in the bottom surface 23 thereof, which has a preferred radius of approximately 0.0150 inches ( 0.381 mm), such as in the embodiments represented in Figures 10 and 11, but the outer radius of the lower surface 23 of the pipette tip differs from that shown in Figures 10 and 11 in that the lower surface 23 has a preferred outer diameter of about 0.0575 inches (1.46 mm). Also, the dimensions of the V-shaped or triangular grooves 28 made concentrically in the lower surface 23 of the pipette tip are substantially the same as those of the embodiment illustrated in Figures 10 and 11 of the drawings. However, the inside edge of the opening 32 defined in the bottom surface 23 of the innermost slot preferably has a radius of about 0.0250 inches (0.635 mm), and the inside edge of the opening 32 defined in the bottom surface 23 The outermost groove preferably has a radius of about 0.0375 inches (0.953 mm).

Figures 14 and 15 illustrate another embodiment of the pipette tip of the present invention in which one or more deeper grooves 28, which are preferably triangular or V-shaped in cross section, are made in the lower surface. 23 from the pipette tip and are arranged concentrically around the central opening 24. More specifically the triangular slot (s) 28 may have two opposite side walls 30 spaced apart at an angle preferably about twenty-three (23) degrees diverging from the apex of the slot to form an opening 32 of preferably about 0.008 inches (0.203 mm) on the bottom surface 23. Triangular groove (s) 28 is preferably cut into bottom surface 23 to a depth of about 0.020 inches (0.508 mm).

In the embodiment of the present invention illustrated in Figures 14 and 15 of the drawings, the diameter of the opening of the tip 24 is preferably approximately 0.030 inches (0.762 mm), and the outer periphery of the bottom surface 23 has a diameter of approximately 0.105 inches (2.67 mm). The inner edge of the innermost slot opening 32 preferably has a radius of about 0.024 inches (0.61 mm) and the inner edge of the outermost slot opening 32 preferably has a radius of about 0.036 inches (0.914 mm). ).

Figures 16 and 17 illustrate yet another embodiment of the pipette tip of the present invention that is similar in many respects to the embodiment of the pipette tip depicted in Figures 14 and 15. The outer diameter of the surface The bottom 23 is preferably about 0.115 inches (2.92 mm), while the diameter of the tip opening 24 is preferably about 0.030 inches (0.762 mm). Again, one or more triangular grooves 28 (when viewed in cross section) are made in the bottom surface 23 and disposed concentrically around the central opening 24. The triangular slot (s) 28 may have two opposing side walls 30 spaced apart at an angle of preferably about twenty-three (23) degrees diverging from the apex of the slot to form an opening 32 of preferably about 0.008 inches (0.203 mm) on bottom surface 23. Triangular groove (s) 28 are preferably cut into bottom surface 23 to a depth of about 0.020 inches (0.508 mm).

In the embodiment depicted in Figures 16 and 17 of the drawings, the inner edge of the opening 32 of the innermost slot preferably has a radius of about 0.026 inches (0.66 mm) and the inner edge of the opening 32 The outermost groove preferably has a radius of about 0.038 inches (0.965 mm).

Figures 18 and 19 illustrate yet another embodiment of the pipette tip of the present invention. In this embodiment, a drip edge 70 is provided that surrounds the periphery of the bottom surface 23 and extends axially outward therefrom. Preferably, the drip edge 70 has a radial width of about 0.0100 inches (0.254 mm) and extends from the bottom surface 23 of the pipette tip a distance of about 0.0050 inches (0.127 mm).

In the embodiment shown in Figures 18 and 19, a triangular or V-shaped slot 28 is made in the bottom surface 23 and is arranged concentrically around the central opening 24. More specifically, the triangular slot 28 has two side walls opposing 30 spaced an angle preferably about ninety (90) degrees diverging from the apex of the slot to form an opening 32 of

ES 2 397 544 T3 preferably about 0.0100 inches (0.254 mm) on bottom surface 23. Triangular groove 28 is preferably cut into bottom surface 23 to a depth of about 0.0050 inches (0.127 mm).

In the embodiment of the pipette tip shown in Figures 18 and 19, the radius of the opening of the tip 24 is preferably about 0.0150 inches (0.381 mm), and the outside diameter of the bottom surface 23 is approximately 0.1050 inches (2.67 mm). The inner edge of the opening 32 of the slot 28 preferably has a radius of about 0.0250 inches (0.635 mm) and the radial inner edge of the drip edge 70 preferably has a radius of about 0.0425 inches (1.08 mm). ). The groove 28 and drip edge 70 increase the effective surface area of ​​the lower surface 23 of the pipette tip between the central opening 24 and the outer edge of the lower surface 23 to inhibit the flow of fluid passing through the tube. central opening 24 of the pipette tip toward the outer edge of the bottom surface 23 and thus minimizes the possibility of fluid drifting to the outer surface of the side wall of the pipette tip.

Figures 20 and 21 illustrate yet another embodiment of the pipette tip of the present invention, in which one or more rounded or semi-circular (in cross-sectional) grooves 72 are made in the lower surface 23 of the pipette tip. . Again, the semi-circular grooves 72 can be arranged concentrically around the central opening 24, or they can be arranged non-concentrically or spirally around the central opening.

Figures 22 and 23 illustrate another embodiment of the pipette tip of the present invention in which a groove 28 is made in the bottom surface 23 of the pipette tip and spirally disposed around the central opening 24.

Figures 24 and 25 illustrate a pipette tip made in accordance with another form of the present invention, in which a groove 28 is made in the bottom surface 23 of the tip and disposed therein around the central opening 24 in one direction. coil with portions thereof partially extending radially inward and outward on the lower surface of the pipette tip. The purpose of said serpentine groove 28, as well as the purpose of the grooves made in the lower surface 23 of the pipette tip described above and shown in Figures 4 to 23, is to increase the effective surface area of ​​the lower surface 23 of the pipette tip, that inhibits the flow of the plasma / serum fluid from the central opening 24 therethrough to the outer surface of the pipette tip in order to minimize the possibility of the fluid sample drifting to the outer surface of the tube. side wall of the pipette tip.

Another shape of pipette tip made in accordance with the present invention is illustrated in Figures 26 and 27. In this case, one or more grooves 28 made in the bottom surface 23 of the pipette tip may extend radially from the central opening 24 to the outer edge of the lower surface 23. Again, the radial grooves 28 increase the total surface area of ​​the lower surface 23 of the pipette tip, preventing sample fluid from flowing from the central opening to the outer edge of the lower surface, where there may be otherwise displaced to the outer surface of the side wall of the pipette tip and may affect the accuracy of the volume of fluid dispensed on a reagent test slide.

Hitherto, the grooves have been described made in the lower surface 23 of the pipette tip. However, it should be noted that the bottom surface can take on other shapes and characteristics that increase the effective surface area of ​​the bottom surface 23 and thus prevent the sample fluid from flowing from the central opening 24 to the edge. exterior of the lower surface 23 of the pipette tip. For example, as shown in Figures 28 and 29 of the drawings, one or more projections 74, which may be triangular, rectangular or semi-circular in cross section, may be made on the lower surface 23 of the pipette tip and extend towards the outside of it. Said projections 74 may be arranged in a spiral, concentrically or non-concentrically on the lower surface 23 around the central opening 24 made in the pipette tip. Said ridges 74 increase the effective surface area of ​​the pipette tip and thus prevent sample fluid from flowing from the central opening 24 to the outer edge of the lower surface 23.

Furthermore, the lower surface 23 of the pipette tip of the present invention, with or without grooves, may have a convex shape, extending axially outward from the bottom of the pipette tip, as illustrated in Figures 30 and 31 of the drawings. The convex shape of the lower surface 23 of the pipette tip effectively increases the total surface area of ​​the lower surface 23 of the pipette tip, preventing sample fluid from flowing from the central opening 24 to the outer edge of the pipet. the lower surface 23 to minimize the possibility of fluid reaching the outer edge of the lower surface 23 and moving to the outer surface of the side wall of the pipette tip. The convex shaped tip also serves to reduce the volume of fluid that could remain adhering to the pipette tip. For example, if the test slide on which fluid is being dispensed tends to repel fluid, the convex shape decreases the likelihood that an unintended amount of liquid will remain on the tip after application.

The addition of grooves or projections made in the lower surface 23 of the pipette tip 14 hereof

ES 2 397 544 T3 invention, or increasing the total surface area of ​​the bottom surface, reduces the rare problem of zone failure due to inaccurate sample dispensing volume that occurs in conventional pipette design, since than the grooves, the ridges or a larger surface area prevent droplet passing through opening 24 from flowing to the outer surface of side wall 16 of pipette tip 14 and traveling to the outer surface of the pipette tip. A more accurate measurement of fluid on the test slide with chemical reagent (or in a vial containing a chemical reagent) is made by the pipette tip of the present invention, even when the pipette tip of the present invention is made with the preferred material, polypropylene, which exhibits affinity for some fluids, such as serum and blood plasma.

Furthermore, although the preferred embodiments have been described primarily with reference to chemical blood analyzers, those skilled in the fluid dispensing art will clearly appreciate that the present invention has applications outside of this field.