WO1998011988A1

WO1998011988A1 - Pipettor tip ejection

Info

Publication number: WO1998011988A1
Application number: PCT/US1997/016418
Authority: WO
Inventors: Donald Malinoff
Original assignee: Bel-Art Products, Inc.
Priority date: 1996-09-19
Filing date: 1997-09-17
Publication date: 1998-03-26

Abstract

An extended tip ejection button (50) in a manual, liquid pipettor (10) enables the user to release a used tip (40) without fear of drawing unwanted residual liquid, aerosols, or vapors back into the pipettor (10) after discharge of the liquid. An extension (60) can be placed on the tip ejection buttons (50) of commercially-available pipettors (10). Alternatively, a longer tip ejection button (110) can be provided for the pipettor (10).

Description

PIPETTOR TIP EJECTION

Technical Field and Background Art

A manually-operated liquid pipettor allows one to draw and dispense small, measured quantities of a liquid using a suction method. First, the pipettor draws liquid from a reservoir into a disposable tip attached to the nozzle of the pipettor. Second, the pipettor is placed over the desired point of delivery and the liquid is pushed out of the tip. Third, the pipettor plunger is allowed to retract.

After the liquid has been dispensed, aerosols and perhaps even some quantity of liquid may remain in the used pipettor tip. Through suction, these residual aerosols and liquids will migrate back into the pipettor nozzle when the plunger retracts. Once in the nozzle, they will be delivered in the next pipettor task, causing contamination of the second and subsequent delivery points.

The problem of such contaminants can be alleviated by using a filter in the disposable tip to block their passage into the pipettor body. However, the filter does not provide an absolute barrier and significantly adds to the cost of what is already a disposable, single-use item. Another, less-costly approach that would block liquid, aerosols, and vapors from entering the pipettor would be highly desirable.

Brief Description of Drawings A more complete understanding of the present invention, as well as other objects and advantages thereof not enumerated herein, will become apparent upon consideration of the following detailed description and the accompanying drawings, wherein:

Figure 1 is an elevation view of a pipettor; Figure 2 is an elevation view of the pipettor of Figure 1 with an extension on the tip ejection button;

Figures 3 and 4 are two cross-sectional views of the extension;

Figure 5 is an elevation view of the pipettor of Figure 1 with an extended tip ejection button; Figures 6 and 7 are elevation views of the pipettors of Figures 1 and 2, respectively, showing the placement of the user's thumb and the operation of the respective pipettors;

Figures 8 and 9 are elevation views of an alternative pipettor; and Figures 10 and 11 are cross-sectional and bottom views, respectively, of a tip ejection button extension for use with the pipettors of Figures 8 and 9.

Disclosure of Invention and Modes for Carrying Out the Invention The goal of the invention is to eject the used disposable tip of a pipettor before the plunger is allowed to return to its rest position (e.g., by the force of an internal spring). If the used tip is removed before the plunger retracts, it will not be able to pull liquid, aerosols, or vapor back from the used tip into the pipettor nozzle. The tip is ejected by pushing down on the tip ejection button while maintaining the plunger in a fully-depressed state.

One embodiment of the invention is an extension for the tip ejection button, allowing the user to eject the tip without removing the thumb from the plunger. Since the extension brings the top of the tip ejection button closer to the top of the depressed plunger, the user can eject the tip by pulling the thumb down. In a variation of this embodiment, the tip ejection button itself extends upward from the pipettor body, and therefore closer to the top of the plunger, eliminating the need for an extension.

For the purposes of describing the invention, Figure 1 shows a typical pipettor 10 of the kind disclosed in U.S. Patent No. Re. 32,210 (incorporated herein by reference). The elements relevant to this discussion are a pipettor body 20, a nozzle 22, a plunger 30, a detachable tip 40, and a tip ejection button 50. The tip ejection button 50 has an actuating surface 52, with an edge 54, and a shaft 56. Although the discussion here will focus on the pipettor shown in the patent, it should be understood that this invention may be used with any pipettor, including those shown in U.S. Patent No. 4,009,611 (Koffer et al.), No. 4, 151,750 (Suovaniemi et al.), No. 4,268,481 (Suovaniemi et al.), No. 4,418,580 (Satchell et al.), No. 5, 104,624

(Labriola), No. 5,364,596 (Magnussen, Jr. et al.), and No. 5,435, 197 (Telimaa et al.), all of which are incorporated herein by reference.

The user will initially insert the tip 40 into a liquid reservoir (not shown) from which liquid will be drawn, push down the plunger 30, applying the thumb to the top or actuating surface 32 of the plunger 30, and then slowly release the plunger 30, drawing the fluid into the tip 40. The user will then place the tip 40 over (or in) the location where the liquid is to be dispensed. At that location, the plunger 30 is again depressed, causing the liquid to exit the tip 40. To insure that nothing is drawn back into the tip 40 after discharge of the liquid, the now-spent tip 40 should be detached from the pipettor body 20 before the plunger 30 is released. Since the tip ejection button 50 is in the vicinity of the user's thumb, it would be ideal to use the thumb to depress the tip ejection button 50. Because the actuating surface 52 of the tip ejection button 50 is some distance from the underside of the user's thumb even when the plunger 30 is fully depressed, it would be awkward and physically straining — and ultimately injurious — for the user to accomplish this manoeuver without removing the thumb from the plunger 30 and thus allowing the plunger 30 to retract. If the actuating surface 52 of the tip ejection button 50 was adjacent the thumb when the plunger 30 is fully depressed, the user could activate the tip ejection button 50 with the underside of thumb without releasing the plunger 30. As shown in Figure 2, this may be accomplished by providing an extension 60 on the tip ejection button 50, bringing the actuating surface 52 of the tip ejection button 50 closer to the position of the actuating surface 32 of the plunger 30, and therefore closer to the user's thumb.

In the case of the pipettor 10 of Figures 1 and 2, the actuating surface 52 and the edge 54 extend outwardly from the shaft 56 of the tip ejection button 50, providing a structure to which the extension 60 can rigidly attach. The extension 60 is shown again in the cross- sectional views of Figures 3 and 4. The extension 60 has an actuating surface 62, a channel 64, and an opening 66 to admit the shaft 56 of the tip ejection button 50.

The channel 64 and opening 66 conform to the contours of the actuating surface 52, edge 54, and shaft 56 to securely grip the tip ejection button 50. As can be seen from Figure 1 , there is clearance around the edge 54 of the actuating surface 52 on at least three sides. If there is no clearance on the side nearest the plunger, the extension 60 must be configured accordingly, as will readily occur to those skilled in the art. Depending on the particular pipettor, the extension 60 can be modified to attach to the tip ejection button 50 utilizing techniques well-known in the art. The extension 60 may be fabricated from virtually any material that can be fashioned into the desired shape and fastened securely to the tip ejection button 50. Such materials include thermoplastic resin, silicone, nylon, aluminum, wood, stainless steel, fiber, rubber, glass-filled polymers, and others as will readily occur to those skilled in the art. The extension 60 can be secured to the tip extension button 50 by a number of means such as rubber-based cement, epoxy, super glue gel, a spring metal clip, a screw, threaded rod or bolt, heat-cured cement, or a double-sided adhesive patch. In lieu of adding an extension to the tip ejection button 50 of the pipettor 10

Figure 1, the tip ejection button itself could be made longer, alleviating the need to add an extension. As illustrated in Figure 5, the pipettor 100 has an elongated tip ejection button 110 having an elongated shaft 120. It should be appreciated that the height of the extension 60 (Figure 2), or of the elongated tip ejection button 110 (Figure 5), relative to the actuating surface 32 of the plunger 30, can be selected to suit the user and the particular pipettor employed. If desired, the two surfaces can be approximately level.

The effectiveness of the extension 60 of Figure 2 and the elongated tip extension button 110 of Figure 5 can be seen in Figures 6 and 7, respectively. In both of those figures, the user's thumb is shown on the plunger 30. (For clarity, only the thumb is shown; in actuality, the user's fingers would wrap around the pipettor body to the surface visible in both figures.) Because of the relative positions of the actuating surface 62 of the extension 60 (Figure 6) and the plunger 30, the flesh under the first segment 200 of the thumb (the first phalanx) rests directly on the extension 60. When the plunger 30 is fully depressed to discharge the fluid in the tip 40, further downward motion of the thumb (principally the first segment 200 and perhaps the joint 210 between the first segment 210 and the second phalanx or segment 220) will depress the extension 60 and in turn the tip ejection button 50, causing release of the tip 40. Similarly, in Figure 7, the first segment 200 of the thumb rests directly on the elongated tip extension button 110. Again, after the plunger 30 has been fully depressed, further downward motion of the thumb will depress the elongated tip ejection button 110.

Although the foregoing discussion has focused upon the pipettor shown in Figure 1 , the tip ejection button extension will work with pipettors of other designs. Figure 8 shows a pipettor 300 with a tip ejection button 302 and again in Figure 9 with an extension 310 on the tip ejection button 302. Since there is no clearance below the tip ejection button 302 when it is fully depressed nor is there clearance between the button 302 and the body 308 of the pipettor 300, the extension 310 must attach to the top and side surfaces 304 and 306 of the tip ejection button 302. The extension 310 is further illustrated in Figure 10 (section 10-10) and Figure 11 (bottom view), which show a channel 312 in the extension 310 that conforms to the contours of the top and side surfaces 304 and 306 of the tip ejection button 302.

While there has been described what is believed to be the preferred embodiment of the invention, those skilled in the art will recognize that other and further modifications may be made thereto without departing from the spirit of the invention, and it is intended to claim all such embodiments that fall within the true scope of the invention.

Claims

What is claimed is:

1. A manual, thumb-operated pipettor, comprising: a pipettor body; a disposable pipette tip detachably affixed to the pipettor body; means for drawing liquid into the tip and subsequently releasing the liquid through the tip; first means for enabling the means for drawing and releasing, the first means travelling between an undepressed position and a depressed position; means for ejecting the tip from the pipettor body; second means for enabling the means for ejecting, the second means travelling between an undepressed position and a depressed position; and extension means, attached to the second means, the extension means having an actuating surface, where the actuating surface is proximate to the thumb when the first means is in the depressed position and the second means is in the undepressed position.

2. A pipettor as set forth in claim 1, where the actuating surface is immediately adjacent the thumb when the first means is in the depressed position and the second means is in the undepressed position.

3. A pipettor as set forth in claim 1, where the actuating surface is in intimate contact with the thumb when the first means is in the depressed position and the second means is in the undepressed position.

4. A manual, thumb-operated pipettor, comprising: a pipettor body; a disposable pipette tip detachably affixed to the pipettor body; means for drawing liquid into the tip and subsequently releasing the liquid through the tip; first means for enabling the means for drawing and releasing, the first means travelling between an undepressed position and a depressed position; means for ejecting the tip from the pipettor body; and second means for enabling the means for ejecting, the second means having an actuating surface and travelling between an undepressed position and a depressed position, where the actuating surface is proximate to the thumb when the first means is in the depressed position and the second means is in the undepressed position.

5. A pipettor as set forth in claim 4, where the actuating surface is immediately adjacent the thumb when the first means is in the depressed position and the second means is in the undepressed position.

6. A pipettor as set forth in claim 4, where the actuating surface is in intimate contact with the thumb when the first means is in the depressed position and the second means is in the undepressed position.

7. A manual, thumb-operated pipettor, comprising: a pipettor body; a disposable pipette tip detachably affixed to the pipettor body; means for drawing liquid into the tip and subsequently releasing the liquid through the tip; first means for enabling the means for drawing and releasing, the first means having an actuating surface and travelling between an undepressed position and a depressed position; means for ejecting the tip from the pipettor body; and second means for enabling the means for ejecting, the second means having an actuating surface and travelling between an undepressed position and a depressed position, where the actuating surface of the second means is proximate to the actuating surface of the first means when the first means is in the depressed position and the second means is in the undepressed position.

8. A pipettor as set forth in claim 7, where the second means comprises an extension.

9. A pipettor as set forth in claim 7, where the actuating surface of the second means is approximately level with respect to the actuating surface of the first means when the first means is in the depressed position and the second means is in the undepressed position.

10. A pipettor as set forth in claim 9, where the second means comprises an extension.

11. An extension for a manual, thumb-operated pipettor comprising a pipettor body, a disposable pipette tip detachably affixed to the pipettor body, means for drawing liquid into the tip and subsequently releasing the liquid through the tip, plunger means for enabling the means for drawing and releasing, the plunger means travelling between an undepressed position and a depressed position, means for ejecting the tip from the pipettor body, and a tip ejection button for enabling the means for ejecting, the tip ejection button travelling between an undepressed position and a depressed position, the extension being applied to the tip ejection button and comprising: an actuating surface; and means for attaching the extension to the tip ejection button; where the actuating surface is proximate to the thumb when the plunger means is in the depressed position and the tip ejection button is in the undepressed position.

12. An extension as set forth in claim 11 , where the means for attaching the extension to the tip ejection button comprises channel means for securing the extension to the tip ejection button, the channel means having a contour complementary to the contour of the tip ejection button.

13. An extension as set forth in claim 11 , where the actuating surface is immediately adjacent the thumb when the plunger means is in the depressed position and the tip ejection button is in the undepressed position.

14. An extension as set forth in claim 11, where the actuating surface is in intimate contact with the thumb the plunger means is in the depressed position and the tip ejection button is in the undepressed position.

15. An extension as set forth in claim 11, where the plunger means has an actuating surface and where the actuating surface of the extension is approximately level with respect to the actuating surface of the plunger means when the plunger means is in the depressed position and the tip ejection button is in the undepressed position.

16. A method of operating a manual, thumb-operated pipettor comprising a pipettor body, a disposable pipette tip detachably affixed to the pipettor body, a plunger for drawing liquid into the tip and subsequently releasing the liquid through the tip, and an elongated tip ejection button for ejecting the tip from the pipettor body, the method comprising the steps of: fully depressing the plunger with the thumb and subsequently releasing the plunger, drawing a predetermined quantity of liquid into the tip; fully depressing the plunger with the thumb, causing release of the liquid through the tip; without removing the thumb from the plunger, depressing the elongated tip ejection button with the underside of the thumb, ejecting the used tip from the pipettor body; and releasing the plunger and the elongated tip ejection button.

17. A method as set forth in claim 16, further including the step of attaching an extension to the tip ejection button before the steps of fully depressing the plunger.

18. A method as set forth in claim 16, where the step of depressing the elongated tip ejection button includes the step of maintaining the thumb on the plunger. AMENDED CLAIMS

[received by the International Bureau on 18 February 1998 ( 18.02.98) ; original claims 4-6 amended ; origina l claims 1 -3 and 7-18 cancel led; new claims 19-28 added ; {3 pages ) ]

4. A manual, thumb-operated pipettor, comprising: a detachable pipette tip; means for drawing liquid into the tip and subsequently releasing the liquid; first means for enabling the means for drawing and releasing, the first means being thumb-actuated and traveling between an undepressed position and a depressed position; means for ejecting the tip from the pipettor; and second means for enabling the means for ejecting, the second means comprising a thumb-actuated actuating surface sufficiently proximate to the thumb when the first means is in the depressed position to permit the thumb to depress the actuating surface while the thumb remains on the first means and retains the first means in the depressed position.

5. A pipettor as set forth in claim 4, where the actuating surface is immediately adjacent the thumb when the first means is in the depressed position.

6. A pipettor as set forth in claim 4, where the actuating surface is in intimate contact with the thumb when the first means is in the depressed position.

19. A pipettor as set forth in claim 4, where the second means further comprises means for extending the second means and the thumb-actuated actuating surface is on the means for extending.

20. A manual, thumb-operated pipettor, comprising: a detachable pipette tip; means for drawing liquid into the tip and subsequently releasing the liquid; a plunger for enabling the means for drawing and releasing, the plunger being thumb-actuated and traveling between an undepressed position and a depressed position; means for ejecting the tip from the pipettor; and an elongated tip ejection button for enabling the means for ejecting, the tip ejection button comprising a thumb-actuated actuating surface sufficiently proximate to the thumb when the plunger is in the depressed position to permit the thumb to depress the actuating surface while the thumb remains on the plunger and retains the plunger in the depressed position.

21. A pipettor as set forth in claim 20, where the tip ejection button further comprises an extension and the actuating surface is on the extension.

22. An apparatus for ejecting a detachable pipette tip from a manual, thumb-operated pipettor comprising means for drawing liquid into the tip and subsequently releasing the liquid, and a plunger for enabling the means for drawing and releasing, the plunger traveling between an undepressed position and a depressed position, comprising: means for ejecting the tip from the pipettor; and means for enabling the means for ejecting, the means for enabling comprising a thumb-actuated actuating surface sufficiently proximate to the thumb when the plunger is in the depressed position to permit the thumb to depress the actuating surface while the thumb remains on the plunger and retains the plunger in the depressed position.

23. An apparatus as set forth in claim 22, where the means for enabling further comprises means for extending the means for enabling and the thumb-actuated actuating surface is on the means for extending.

24. An apparatus as set forth in claim 22, where the actuating surface is immediately adjacent the thumb or in intimate contact with the thumb when the plunger is in the depressed position.

25. A pipette tip ejector for ejecting a detachable pipette tip from a manual, thumb-operated pipettor comprising means for drawing liquid into the tip and subsequently releasing the liquid, and a plunger for enabling the means for drawing and releasing, the plunger traveling between an undepressed position and a depressed position, comprising: means for ejecting the tip from the pipettor; and an elongated tip ejection button for enabling the means for ejecting, the tip ejection button comprising a thumb-actuated actuating surface sufficiently proximate to the thumb when the plunger is in the depressed position to permit the thumb to depress the actuating surface while the thumb remains on the plunger and retains the plunger in the depressed position.

26. A pipette tip ejector as set forth in claim 25, where the tip ejection button further comprises an extension and the actuating surface is on the extension.

27. A method of ejecting a detachable pipette tip from a manual, thumb-operated pipettor comprising means, enabled by a plunger, for drawing liquid into the tip and subsequently releasing the liquid, and an elongated tip ejection button for ejecting the tip from the pipettor, the method comprising the steps of: after depressing the plunger with the thumb to release liquid from the tip, holding the plunger down with the thumb; and depressing the elongated tip ejection button with the underside of the thumb to eject the tip from the pipettor while keeping the thumb on the plunger and keeping the plunger depressed.

28. A method as set forth in claim 27, further including the step of first attaching an extension to the tip ejection button.

STATEMENT UNDER ARTICLE 19

Enclosed are replacement pages 7-9 for original pages 7-10. Additionally, a renumbered abstract page 10 (originally numbered 11) is enclosed.

Originally, claims 1-20 were submitted. Claims 1-3 and 7-18 are canceled, claims 4-6 are amended, and new claims 19-28 are added. Claims 4-6 are shown below with brackets and underscoring to illustrate the amendments made thereto:

4. (Amended) A manual, thumb-operated pipettor, comprising:

[a pipettor body;] a [disposable] detachable pipette tip [detachably affixed to the pipettor body]; means for drawing liquid into the tip and subsequently releasing the liquid [through the tip]; first means for enabling the means for drawing and releasing, the first means [travelling] being thumb-actuated and traveling between an undepressed position and a depressed position; means for ejecting the tip from the pipettor [body]; and second means for enabling the means for ejecting, the second means [having an actuating surface and travelling between an undepressed position and a depressed position] comprising a thumb-actuated actuating surface [, where the actuating surface is] sufficiently proximate to the thumb when the first means is in the depressed position [and the second means is in the undepressed position] to permit the thumb to depress the actuating surface while the thumb remains on the first means and retains the first means in the depressed position.

5. (Amended) A pipettor as set forth in claim 4, where the actuating surface is immediately adjacent the thumb when the first means is in the depressed position [and the second means is in the undepressed position].

6. (Amended) A pipettor as set forth in claim 4, where the actuating surface is in intimate contact with the thumb when the first means is in the depressed position [and the second means is in the undepressed position].