BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings, which illustrate what is currently regarded as the best mode for carrying out the invention:
FIG. 1 is an illustration of a first embodiment of a pipette tip of the present invention;
FIG. 2 is an illustration of the outer component of the pipette tip of FIG. 1;
FIG. 3A illustrates the inner component of FIG. 1;
FIG. 3B depicts a perspective view of the inner component of FIG. 1;
FIG. 4 is a perspective view of a second embodiment of a pipette tip of the present invention;
FIG. 5 is an illustration of a third embodiment of a pipette tip of the present invention;
FIG. 6 depicts a fourth embodiment of a pipette tip of the present invention, mounted on a pipette;
FIG. 7A depicts a fifth embodiment of a pipette tip of the present invention;
FIG. 7B depicts a close-up view of the junction of a first component and a second component of the pipette tip of FIG. 7A;
FIG. 7C shows a pipette tip mounting shaft and ejection mechanism;
FIG. 8 depicts a mold of the present invention; and
FIG. 9 illustrates a flow chart for a method of making a pipette tip of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 depicts a first embodiment of a pipette tip, generally 100, of the present invention. The pipette tip 100 comprises a hollow, elongated, tapered body 200 (also “outer component 200”) with a proximal open end 230 for receiving and releasably mating with a mounting shaft of a manual or mechanical pipette device (see FIG. 7C).
The pipette tip 100 comprises two components respectively formed of materials selected for their distinct but different properties. An outer component 200, shown as a hollow, elongated, tapered body, telescopically receives an inner component 300. For convenience of description, the outer component 200 is referred to as “tapered.” Within the context of this disclosure, however, the term “tapered” refers to an overall reduction in diameter throughout the length of the body. The outer component 200 may, in practice, include cylindrical segments. In any case, outer component 200 has an interior wall 220 defining an inner passageway 210. The proximal open end 230 of outer component 200 is of greater diameter than the distal open end 240. The proximal open end 230 is configured to receive the inner component 300 and the mounting shaft of a pipette device. The distal open end 240 is configured to draw a liquid into the inner passageway 210.
The outer component 200, shown in detail in FIG. 2, includes a rim or flange 270, which protrudes beyond the inner component 300 (FIG. 1), and extends radially outward from the remainder of the outer component 200.
As illustrated, the inner component 300 of the pipette tip is generally annular. It may comprise a separate, generally cylindrical component, as shown, but in other embodiments, may comprise a coating on an interior wall 220 of the outer component 200. The inner component 300 may cover only an end segment of the interior wall 220, proximal to proximal open end 230. The embodiment of inner component 300 (shown in detail in FIGS. 3A and 3B) comprises an annular body 370 defining a passageway 310 and comprising a plurality of segments 370a, 370b, 370c, 370d, and 370e. The passageway 310 decreases in diameter from a first end segment 370a to a second end segment 370e. The first end segment 370a defines a tapered section of the passageway 310. The adjacent segment 370b defines a cylindrical portion of the passageway 310. A third segment 370c defines a tapered portion of the passageway 310, and the next adjacent segment 370d defines a second cylindrical section of the passageway with a diameter smaller than the first cylindrical section. The passageway 310 is thereby configured to receive the mounting shaft of a pipette in fluid-tight sealed relationship. Alternative embodiments have passageways 310 configured to present a uniformly tapered interior wall, a cylindrically shaped interior wall, or any number of tapered or cylindrical sections, provided that they are shaped and dimensioned to effect a fluid-tight seal with the mounting shaft of a pipette probe. The material from which the inner component 300 is constructed is ideally sufficiently compliant to deform as required to receive and seal about the mounting shaft.
Returning to FIG. 1, the pipette tip 100 comprises a tapered, tubular body with a passageway 110 therethrough. The passageway 110 is defined by an inside-facing surface 120. The inside-facing surface 120 includes a first portion 220, corresponding to the inside-facing surface of the outer component 200. A second portion 320 of the inside-facing surface 120 of the pipette tip 100 corresponds to the inside-facing surface of the inner component 300. The material of the inner component 300 is different than the material of the outer component 200. The material of the inside-facing surface first portion 220 is, therefore, different than the material of the inside-facing surface second portion 320. The inside-facing surface second portion 320 may comprise a compliant material, and be configured to receive and sealingly engage with a mounting shaft of a pipette.
A second embodiment of a pipette tip of the present invention is shown in FIG. 4. The pipette tip 400 includes an outer component 500 and an inner component 600. The outer component 500 includes circumferentially spaced longitudinally extending fins 550 on the outer surface 505. The fins 550 provide lateral stability. The outer component 500 further includes circumferentially spaced apertures 560 about a first open end 530 thereof. The apertures 560 may be useful for the formation of the pipette tip 400, as described in further detail subsequently in this disclosure.
The inner component 300, 600 may comprise an elastomer, such as a rubber, a foam, a thermoplastic elastomer (TPE), or a thermoplastic vulcanizate. A TPE combines the look, feel and elasticity of conventional thermoset rubber with the processing efficiency of a plastic. The melt-processability makes it suitable for high-volume injection molding and extrusion. One suitable thermoplastic vulcanizate is sold under the trade name SANTOPREME™ by Santopreme Specialty Products of Akron, Ohio.
The pipette tip outer component 200, 500 may comprise, by way of example, polypropylene or polystyrene. The pipette tip outer component 200, 500 is preferably resilient enough to be ejected off of a pipette probe, and to have lateral and dimensional stability.
FIG. 7C depicts the mounting shaft 730 of a pipette with an ejection mechanism 750 disposed about the shaft. In use, the mounting shaft 730 may be inserted within the pipette tip 100, 400 with enough force to deform the compliant material of the inner component 300, 600, forming a fluid-tight seal between the mounting shaft peripheral cylindrical surface 740 and the second portion of inside-facing surface 320 of the inner component 300, 600. Fluid may be drawn into the pipette tip 100, 400 with a vacuum through the mounting shaft 730, and the fluid may be expelled, for example, in a different location. The fluid may be drawn in through and expelled from the distal open end 240 of the pipette tip 100, 400. The pipette tip 100, 400 may be pushed off of the mounting shaft 730 with the ejection mechanism 750. The ejection mechanism 750 may comprise an annular body. The mounting shaft 730 may be an element of a manual or an automated pipette.
The compliant material of the inner component 300, 600 enables the pipette tip 100, 400 to be mounted on the pipette device with little or no deformation of the more rigid material of the outer component 200, 500. Therefore, the axial mounting and ejection forces are minimized. In addition, the compliant material of the inner component 300, 600 enables the pipette tip 100, 400 to have a universal fit. That is, the pipette tip 100, 400 of the present invention may be mounted on the mounting shafts of various pipette devices, despite the differing shaft diameters of those devices. For example, a pipette tip 100, 400 having an inner component passageway with a diameter of about 0.172 inches (0.437 centimeters) at the largest open end may fit a pipette-mounting shaft having a diameter between about 0.173 inches (0.438 centimeters) and about 0.183 inches (0.465 centimeters). The material of the inner component may have a durometer between about 50 and about 60, preferably about 55 on the Å scale, and the material may be compressed a maximum of between about 40% and about 65%. Therefore, an inner component having a wall thickness of about 0.010 inches (0.025 centimeters) and a maximum compression of 50% may fit a pipette-mounting shaft having a diameter up to about 0.010 inches (0.025 centimeters) larger tan the inner component passageway.
FIG. 5 depicts a third embodiment of a pipette tip 450 of the present invention. The pipette tip 450 comprises at least two components. The two components shown are formed of different materials having correspondingly different physical properties. The outer component 570 comprises a hollow, elongated, tapered body, with a portion of a second, annular inner component 580 received telescopically therein. The outer component 570 has an interior wall 572 defining a passageway 571. A first, proximal end segment 575 of the outer component 570 has an opening greater in diameter than the opening of a second, distal end segment 574. The segment 575 is configured to receive a first end segment 585 of the inner component 580. A second end segment 587 of the inner component 580 is configured to receive the mounting shaft of the pipette device. The segment 574 of the outer component 570 is configured to draw a liquid into the passageway 501. The segment 587 of the inner component 580 protrudes beyond the outer component 570.
The inner component 580 may comprise an elastomer, such as a rubber, a foam, a thermoplastic elastomer (TPE), or a thermoplastic vulcanizate. The pipette tip inner component 580 is preferably resilient enough to be ejected off of a pipette probe, yet compliant enough to form a fluid-tight seal therewith. The material of the second component may have a durometer between about 60 and about 95, preferably about 87 on the Å scale.
The pipette tip outer component 570 may comprise, by way of example, polypropylene or polystyrene, The pipette tip outer component 570 is preferably relatively more resilient and/or rigid than the material of the inner component 580.
FIG. 6 depicts an alternative embodiment of a pipette tip 650 of the present invention. The pipette tip 650 is a positive displacement pipette tip. It includes an outer component 660 and an inner component 670, each of which may be formed of the materials disclosed as useful in connection with other embodiments of the invention. The inner component 670 is fashioned of a more compliant material than is the outer component 660. The pipette tip 650 is depicted mounted on a pipette 680. The pipette 680 includes a plunger 685 that may be used to draw a liquid 695 into the pipette tip 650, and to dispense the liquid 695 from the pipette tip 650. The pipette tip 650 may have a substantially cylindrical passageway 655 therethrough, with an inside-facing surface of the inner component 670 flush with an inside-facing surface of the outside component 660.
FIGS. 7A and 7B depict an additional embodiment of a pipette tip 700 of the present invention. The pipette tip 700 includes a first component 710 and a second component 720. The first component 710 may comprise a hollow, elongated, tapered body of a relatively more rigid material than the material of the second component 720. The first component may be axially tapered from a first open end 712 (see FIG. 7B) to a second open end 714. The second component 720 may comprise a hollow, substantially cylindrical body with a first open end 722 to a second open end 724 (see FIG. 7B). The second open end 724 of the second component 720 may be configured to telescopically receive the first component 710 therein. The second component 720 may include an annular rim 726 for abutting with the first component 710, and an annular flange 728 for encircling a portion of the same. FIG. 7B depicts a cross-sectional view of the junction of the first component 710 and the second component 720. The inside-facing surface 721 of the second component 720 at the second open end 724 and the inside-facing surface 711 of the first component 710 at the first open end 712 may adjoin to form a substantially continuous interior surface of the pipette tip 700.
The pipette tip 700 comprises a tapered, tubular body with a passageway 701 therethrough. The passageway 701 is defined by an inside-facing surface 702. The inside-facing surface 702 includes a first portion corresponding to the inside-facing surface 711 of the first component 710. A second portion of the inside-facing surface 721 of the pipette tip 700 corresponds to the inside-facing surface of the second component 720. The material of the second component 720 is different than the material of the first component 710. The material of the inside-facing surface first portion 711 is, therefore, different than the material of the inside-facing surface second portion 721. The inside-facing surface second portion 721 may comprise a compliant material and be configured to receive and sealingly engage with a mounting shaft of a pipette.
In use, the pipette tip 450, 700 may be mounted on a mounting shaft 730 (FIG. 7C) of a pipette. The mounting shaft 730 may be inserted within component 580, 720 of pipette tip 450, 700. The component 580, 720 deforms to form an annular fluid-tight seal between the mounting shaft 730 and the component 580, 720. Fluid may be drawn into the pipette tip 450, 700 with a vacuum through the mounting shaft 730, and the fluid may be expelled, for example, in a different location. The fluid may be drawn in through and expelled from an opening of the second end 574, 714 of the pipette tip component 570, 710.
The pipette tip of the present invention may be formed by two-shot molding, also known as double-shot molding, insert molding and over-molding. The inner component may be molded first and the outer component may then be molded around the inner component. Alternatively, the outer component may be molded first, and the inner component may then be molded within the outer component.
As shown in FIG. 8, two mold plates may be provided for a practical molding process. The inner component 300, 600, 670 are molded between a first plate 810 and a second plate 820. The first plate 810 may include a protrusion 815, also known as a core, configured to define the inner surface configuration of component 300, 600, 670. The second plate 820 includes a cavity 825 for receiving the protrusion 815, thereby defining a cavity closely approximating the size and shape of inner component 300, 600, 670. The protrusion 815 is thus configured to define the passageway through the pipette tip 100, 400, 650. A first portion 825a of the cavity 825 is configured to define the outside surface of the inner component 300, 600, 670. A second portion 825b of the cavity 825 may be configured to receive the protrusion 815 with a relatively tight tolerance therebetween. Thus, no molding cavity is created between the protrusion 815 and the cavity second portion 825b. In use, the protrusion 815 may be disposed within the cavity 825, forming a molding cavity to form the inner component 300, 600, 670 of a pipette tip 100, 400, 650. A first molding material may be inserted into the molding cavity from a first molding material source 830.
Subsequent to the formation of the inner component 300, 600, 670, the first plate 810 may be drawn away from the second plate 820. The protrusion 815 with the inner component 300, 600, 670 formed thereabout may thus be removed from the cavity 825.
A third plate 840 is shown, having a protrusion 845 with the inner component 300, 600, 670 formed thereabout. The third plate 840 may be pressed against a fourth plate 850; the fourth plate 850 including a cavity 855 therein. The cavity 855 may be configured for receiving the protrusion 845 and the inner component 300, 600, 670 creating a mold cavity for forming the outer component 200, 500, 660. A second molding material may be inserted into the molding cavity from a second molding material source 860.
The second plate 820 and the fourth plate 850 may comprise a contiguous plate for use with an injection-molding machine having a rotating platen 870. The first plate 810 and the third plate 840 may be a part of the rotating platen 870. After forming the inner component 300, 600, 670 within the cavity 825 of the second plate 820, the first plate 810 with the first component 300, 600, 670 positioned about the protrusion 815 may be drawn away from the second plate 820, rotated, and the mold may be closed with the first plate 810 against the fourth plate 850, and the outer component 200, 500, 660 may be formed therein.
FIG. 9 depicts a flow chat for another method of making a pipette tip 100, 400, 650 of the present invention. The pipette tip 100, 400, 650 may be formed by insert molding. In step 900, the outer component 200, 500, 660 may be formed within a cavity of a first mold, about a first mold core. Next, in steps 910 and 920, the outer component 20, 500, 660 is removed from the first mold cavity, and positioned within a second mold cavity. The outer component 200, 500, 660 may be disposed between a second core and the cavity of the second mold. The second core may include a portion thereof having a diameter smaller than the diameter of the first mold core. A mold material may be injected into the second mold in step 930, and the inner component 300, 600, 670 may be formed between the second core and the outer component 200, 500, 650. The inner component 300, 600, 670 may be bonded to the outer component 200, 500, 650 by molecular bonding of the material of the components, during the molding or with a thermal weld. Alternatively, or in addition to the molecular bonding, mechanical bonding may take place. For example, the outer component 200, 500, 650 may include surface irregularities, which are surrounded by the material of the inner component 300, 600, 670, or shrinking or swelling of the material of the components may take place.
While this invention has been described in certain embodiments, the present invention can be further modified within the spirit and scope of this disclosure. The formation of the pipette tip 100, 400, 650 of the present invention has been described using two-shot molding, forming the inner component, and subsequently forming the outer component about the inner component. However, it will be understood by one skilled in the art that other methods of forming a multi-component pipette tip are within the scope of the present invention. For example, the outer component may be formed prior to the inner component, or other molding methods may be used to form the multiple components. The term “pipette tip” as used herein, is intended to encompass all types of pipette tips, including pipette tips used for automated and manual pipetting, positive displacement pipettes, and all other pipette tips.
This application is, therefore, intended to cover any variations, uses, or adaptations of the invention using its general principles. For example, it is within the scope of the present invention for the inner component 300 shown in FIG. 1 to comprise an O-ring or a sealing ring. Further, this application is intended to cover such departures from the present disclosure as come within the known or customary practice in the art to which this invention pertains and which falls within the limits of the appended claims.
Patent Application
20080078258
