PIPETTE TIP WITH TWO POSITIVE ANGLE STEPS

Abstract

A pipette includes an end section, a first section, a second section and a third section aligned along a central axis of the pipette tip. The end section comprises an orifice for aspirating and dispensing a fluid. A first kink is formed in an inner surface of the pipette tip between the first section and the second section, such that an angle between the inner surface of the first section and the central axis is smaller than an angle between the inner surface of the second section and the central axis. A second kink is formed in the inner surface of the pipette tip between the second section and the third section, such that the angle between the inner surface of the second section and the central axis is smaller than an angle between the inner surface of the third section and the central axis.

Claims

1. A pipette tip comprising: an end section, a first section, a second section and a third section aligned along a central axis of the pipette tip; wherein the end section comprises an orifice for aspirating and dispensing a fluid; wherein a first kink is formed in an inner surface of the pipette tip between the first section and the second section, such that an angle (α1) between the inner surface of the first section and the central axis is smaller than an angle (α2) between the inner surface of the second section and the central axis; wherein a second kink is formed in the inner surface of the pipette tip between the second section and the third section, such that the angle (α2) between the inner surface of the second section and the central axis is smaller than an angle (α3) between the inner surface of the third section and the central axis.

2. The pipette tip of claim 1, wherein an angle between the inner surface of the first section and the inner surface of the second section is larger than 1° and/or is smaller than 5°.

3. The pipette tip of claim 2, wherein an angle between the inner surface of the second section and the inner surface of the third section is larger than 1° and/or is smaller than 5°.

4. The pipette tip of claim 1, wherein the angle (α1) between the inner surface (40b) of the first section and the central axis is larger than 2° and/or smaller than 5°; wherein the angle (α2) between the inner surface of the second section and the central axis is larger than 3° and/or smaller than 9°; wherein the angle (α3) between the inner surface of the third section and the central axis is larger than 4° and/or smaller than 13°.

5. The pipette tip of claim 1, wherein the position of the first kink is chosen, such that an inner volume of the pipette tip between the orifice and the first kink is between 0.3 μl and 0.6 μl; and/or wherein the position of the second kink is chosen, such that an inner volume of the pipette tip between the orifice and the second kink is between 0.8 μl and 1.2 μl.

6. The pipette tip of claim 1, wherein a length of the third section along the central axis is chosen, such that an inner volume of the pipette tip between the orifice and the length is at least a nominal volume of the pipette tip, such that at least 5 μl.

7. The pipette tip of claim 1, wherein the inner surface of the first section is conical; wherein the inner surface of the second section is conical; wherein the inner surface of the third section is conical.

8. The pipette tip of claim 1, wherein a further kink is formed in the inner surface of the pipette tip between the end section and the first section.

9. The pipette tip of claim 1, wherein an angle between the inner surface of the end section and the inner surface of the first section is larger than 2° and/or is smaller than 5°.

10. The pipette tip of claim 1, wherein the inner surface of the end section is cylindrical.

11. The pipette tip of claim 1, wherein a common outer surface of the first section, the second section and the third section is conical.

12. The pipette tip of claim 1, wherein the pipette tip comprises an attachment section for attaching the pipette tip to a nozzle of a laboratory automation device for changing a pressure inside the pipette tip; wherein the attachment section is aligned along the central axis of the pipette tip following the third section.

13. The pipette tip of claim 10, wherein the attachment section is formed, such that a further pipette tip (10′) is partially insertable into the attachment section to at least the third section, for stacking the further pipette tip (10′) and the pipette tip.

14. The pipette tip of claim 1, wherein the pipette tip comprises a cylindrical section aligned along the central axis of the pipette tip following the third section; wherein the cylindrical section is longer than the pipette tip between the orifice and the cylindrical section.

15. The pipette tip of claim 1, wherein the pipette tip comprises a filter section aligned along the central axis of the pipette tip, the filter section following the third section; wherein the inner surface of the filter section comprises ribs extending radially around the central axis.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Below, embodiments of the present invention are described in more detail with reference to the attached drawings.

[0048] FIG. 1 shows a cross sectional view of a pipette tip according to an embodiment of the invention.

[0049] FIG. 2 shows an enlarged view of an end of the pipette tip of FIG. 1.

[0050] FIG. 3 shows a cross sectional view of two pipette tips according to FIG. 1 stacked into each other.

[0051] FIG. 4 shows a cross sectional view of a pipette tip according to a further embodiment of the invention.

[0052] The reference symbols used in the drawings, and their meanings, are listed in summary form in the list of reference symbols. In principle, identical parts are provided with the same reference symbols in the figures.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0053] FIG. 1 shows a pipette tip 10, which can be used with a manual pipette or laboratory automation device. The pipette tip 10 comprises a substantially rotational symmetric body 12 with respect to a central axis A.

[0054] The pipette tip 10 can be divided into several sections of different geometric forms.

[0055] An end section 14 comprises an orifice 16 for aspirating a fluid into an inner cavity 18 of the pipette tip 10. The orifice 16, which may be circular, may have a diameter between 0.3 mm and 1.0 mm and/or the outer end of the pipette tip 10 may have a diameter of about 0.8 mm. The end section 14 may have a length of about 0.5 mm.

[0056] Along the axis A, a first section 20, second section 22 and third section 24 follows the end section 14 in this order. All of these sections as well as the end section are rotational symmetric with respect to the central axis A and/or have a circular cross-section orthogonal to the central axis A. Also, slightly oval cross-sections are possible. The first section 20 has a length of about 2.0 mm, the second section 22 of about 1.2 mm and the third section of about 12.4 mm. Here and in the following, the lengths are dependent on desired volumes for the respective sections in dependence of the diameters of the respective sections.

[0057] The end section 14, the first section 20, the second section 22 and the third section 24 are rotational symmetric with respect to the axis A. Again, slightly oval cross-sections are possible.

[0058] The pipette tip 10 furthermore comprises an attachment section 26 with an opening 28 opposite to the orifice 16. The attachment section 26 is designed for being connected to a nozzle of the a laboratory automation device or handheld pipette, which nozzle may be plugged into the opening 28. At an outer end, the attachment section 26 comprises ribs 30, which extend substantially parallel to the central axis A and which are provided on an outside of the pipette tip 10 and its body 12. In FIG. 1, a cross-section through a pair of opposite ribs 30 is shown. The thickness of a wall 32 of the attachment section 26 besides the ribs 30 is like the thickness of the wall 32 in a region, where no ribs 30 are present any more, i.e. towards the orifice 16.

[0059] The attachment section 26 has a length of about 19 mm. Except the ribs, the attachment section 26 is rotational symmetric with respect to the axis A.

[0060] The attachment section 26 is connected to the third section 24. At an end connected to the third section 24, the attachment section 26 comprises a filter section 34. The filter section 34 is designed for receiving a cylindrical filter piece and/or has inner ribs 36, which circumvent the central axis A on an inside of the pipette tip 10. The filter section 34 has a length of about 4 mm. The filter section 34 is rotational symmetric with respect to the axis A.

[0061] The pipette tip 10 and its body 12 may be made of plastics material. The plastic material may be conductive e. g. by graphite additives or may be non-conductive e. g. polypropylene. The pipette tip 10 may be manufactured by injection moulding, wherein an outer surface 38 is formed by an outer mould tool and an inner surface 40 is formed by an inner mould tool.

[0062] The inner surface 40a of the end section 14 is cylindrical and has the same diameter like the orifice 16. The inner surface 40b of the first section 20, the inner surface 40c of the second section 22 and the inner surface 40d of the third section 24 is conical. The terms “cylindrical” and “conical” relate to the shell surfaces of the respective body. There also may be pipette tips without a cylindrical end section. Such tips may have a very short end section, which may be the lower end of the first section, which provides the orifice.

[0063] It may be that the end of the inner surface 40d of the third section, which goes over into the inner surface of the attachment section 26, opens up shaped like a trumpet, i.e. with continuously increasing surface angle with respect to the central axis A.

[0064] An inner diameter of the first section 20, second section 22 and third section 24 is continuously increasing with increasing distance from the orifice 16. The angle with respect to the central axis A may be constant within a section. The angle increases from section to section with growing distance to the end section.

[0065] FIG. 2 shows an enlarged view of the sections 14, 20, 22, 24 of the pipette tip 10. It can be seen that a kink 42 is formed between the inner surface 40a of the end section 14 and the inner surface 40b of the first section 20, that a kink 44 is formed between the inner surface 40b of the first section 20 and the inner surface 40c of the second section 22 and that a kink 46 is formed between the inner surface 40c of the second section 22 and the inner surface 40d of the third section 24.

[0066] As described above, the accuracy and precision of the amount of fluid to be aspirated and dispensed, when the pipette tip is filled up to the respective kink 44, 46, can be increased. The positions of the kinks 44, 46 can be chosen, such that the accuracy at specific volumes is increased.

[0067] In the embodiment shown in FIGS. 1 and 2, the position of the kink 44 is chosen, such that an inner volume of the pipette tip 10 between the orifice 16 and the kink 44 is about 0.5 μl. Also, the position of the second kink 46 is chosen, such that an inner volume of the pipette tip 10 between the orifice 16 and the second kink 46 is about 1.0 μl.

[0068] The third section 24 may be substantially longer than the first section 20 and the second section 22 and/or may have a substantially larger inner volume. The length of the third section 24 along the central axis A is chosen, such that an inner volume of the pipette tip 10 between the orifice 16 and the length is at least a nominal volume of the pipette tip 10, such that as more than 5 μl, for example 10 μl.

[0069] The kinks 42, 44, 46 are formed by a sudden step in the angle between the inner surface 40 of the pipette tip and the axis A. Each of the angles α.sub.1, α.sub.2, α.sub.3, which are present between the central axis A and the surfaces 40b, 40c, 40d, is higher than the previous one, i.e. the inner surface 40 of the pipette tip 10 opens up at every kink 42, 44, 46. The kink 42 solely may be present in the case of a cylindrical end section 14.

[0070] The angle α.sub.1 between the inner surface 40b of the first section 20 and the central axis A is smaller than the angle α.sub.2 between the inner surface 40c of the second section 22 and the central axis A. The angle α.sub.2 between the inner surface 40c of the second section 22 and the central axis A is smaller than the angle α.sub.3 between the inner surface 40d of the third section 24 and the central axis A.

[0071] As described above, the following ranges of angles have been shown to achieve the beneficial effects of increasing the controllability of aspirating and dispensing and the accuracy at the volumes defined by the kinks 44, 46.

[0072] The angle α.sub.1 between the inner surface 40b of the first section 20 and the central axis A may be larger than 2° and/or smaller than 5°, such as 3°. The angle α.sub.2 between the inner surface 40c of the second section 22 and the central axis A may be larger than 3° and/or smaller than 9°, such as 5°. The angle α.sub.3 between the inner surface 40d of the third section 24 and the central axis A may be larger than 4° and/or smaller than 13°, such as 6.5°.

[0073] The angle β.sub.1 between the inner surface 40b of the first section 20 and the inner surface 40c of the second section 22 is the difference of the angles α.sub.2 and α.sub.1. The angle β.sub.1 is larger than 1° and/or is smaller than 5°. The angle β.sub.2 between the inner surface 40c of the second section 22 and the inner surface 40d of the third section 24 is the difference of the angles α.sub.3 and az. The angle β.sub.2 is larger than 1° and/or is smaller than 5°.

[0074] It is not necessary that the outer surface 38 of the pipette tip 10 also has kinks. In the present embodiment, a common outer surface 38a of the end section 14, the first section 20, the second section 22 and the third section 24 is conical.

[0075] FIG. 3 shows the pipette tip 10 of FIGS. 1 and 2 and a further pipette tip 10′ of the same design. It is shown that the attachment section 26 is formed, such that the further pipette tip 10′ is partially insertable into the attachment section 26 to at least the third section, for stacking the further pipette tip 10′ and the pipette tip 10. The pipette tips 10, 10′ hang in a tray 48 with holes 50. The holes 50 have a smaller diameter than the outside diameter of the ribs 30 and a larger diameter than the outside diameter of the coupling section without ribs 30. The trays 48 are kept at a distance by spacers 52 so that the space for stacking is optimally used.

[0076] The third section 24, which has the largest outer diameter of the sections 14, 20, 22, 24, has an outer diameter smaller than the inner diameter of the attachment section 26 at the opening 28. Furthermore, the length of the attachment section 26 (without the optional filter section 34) is at least 80% of the overall length of the sections 14, 20, 22, 24.

[0077] FIG. 4 shows a pipette tip 10, which additionally comprises a cylindrical section 54 between the third section 24 and the attachment section 26. With the cylindrical section 54, the nominal volume of the pipette 10 can be substantially increased. The cylindrical section 54 is longer than the pipette tip 10 between the orifice 16 and the cylindrical section 54, i.e. longer than the sections 14, 20, 22, 24.

[0078] The other parts of the pipette tip 10 of FIG. 4 can be designed as the corresponding parts of pipette tip 10 of FIGS. 1 to 3. In particular, the pipette tip 10 of FIG. 4 also comprises the kinks 44, 46, which increase the accuracy in aspirating and dispensing as described above.

[0079] The pipette tip 10 of FIG. 4 comprises a kink 56 between the inner surface 40d of the third section 24 and the inner surface 40e of the cylindrical section 54, which however protrudes away from the central axis A contrary to the kinks 42, 44, 46.

[0080] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art and practising the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.