Pipette for use with a pipette tip

Abstract

A pipette comprises a pipette housing comprising an upper end and a lower end, a nipple configured to contact and retain a pipette tip, a drive apparatus configured to aspirate a liquid specimen into the pipette tip and expel the liquid specimen from the pipette tip, and an ejection apparatus. The ejection apparatus comprises a curved support rotatably mounted within the pipette housing, an ejection rod, a first sensing element positioned on the ejection rod and configured to be guided on a first curve on a perimeter of the curved support, and an operating element coupled to the curved support and configured to rotate relative to the pipette housing. The ejection apparatus is configured to rotate the curved support out of a start position by rotating the operating element. The first curve displaces the first sensing element downward a the ejection rod moves the pipette tip off of the nipple.

Claims

1. A pipette for use with a pipette tip, the pipette comprising: a pipette housing comprising an upper end and a lower end; a nipple positioned on the lower end of the pipette housing and configured to contact and retain the pipette tip; a drive apparatus configured to aspirate a liquid specimen into the pipette tip and expel the liquid specimen from the pipette tip; and an ejection apparatus comprising, a curved support rotatably mounted within the pipette housing, an ejection rod guided within the pipette housing in a longitudinal direction of the nipple, a first sensing element positioned on the ejection rod, wherein the first sensing element is configured to be guided on a first curve positioned on a perimeter of the curved support, and an operating element coupled to the curved support and configured to project from the pipette housing, the operating element configured to rotate relative to the pipette housing, wherein the ejection apparatus is configured to rotate the curved support out of a start position by rotating the operating element, and wherein the first curve displaces the first sensing element downward so that the ejection rod moves the pipette tip off of the nipple.

2. The pipette according to claim 1, wherein the nipple comprises a means for a form-fit connection to a pipette tip so that a pipette tip can be inserted onto the nipple while elastically deforming the nipple.

3. The pipette according to claim 2, wherein the pipette tip is configured to elastically expand before a form-fit connection with the nipple.

4. The pipette according to claim 2, further comprising a locking apparatus comprising, a locking sleeve arranged concentric to the nipple, a control rod configured to project upward from the locking sleeve, wherein the locking sleeve and the control rod are configured to be guided toward the nipple in the pipette housing, and a second sensing element configured to project from the control rod.

5. The pipette according to claim 4, further comprising a second curve positioned on the perimeter of the curved support and configured to guide the second sensing element.

6. The pipette according to claim 5, wherein when the operating element is in the start position, the second sensing element is configured so that the locking sleeve contacts at least one of the nipple and the pipette tip, wherein the locking sleeve prevents release of the pipette tip from the nipple, wherein the locking sleeve is configured to be displaced upward by rotating the operating element so that at least one of the nipple and the pipette tip is at least partially released, and wherein the ejection rod is configured to push the pipette tip off of the nipple.

7. The pipette according to claim 5, wherein when at least one of the first and second sensing elements is positioned in the start position, at least one of the first curve comprises symmetrically arranged sections on both sides of a high point, and the second curve comprises symmetrically arranged sections on both sides of a low point.

8. The pipette according to claim 5, wherein at least one of the first curve and the second curve comprises a groove.

9. The pipette according to claim 5, wherein the first curve comprises a shape of one of an inverted V, an inverted U, and an inverted Y, and wherein the second curve comprises a shape of one of an upright V and an upright U.

10. The pipette according to claim 4, wherein at least one of the first sensing element and the second sensing element comprises one of a guide pin, a rotatably mounted ball, a roller, a sleeve, and a roller bearing mounted on a pin.

11. The pipette according to claim 4, further comprising a third sensing element concentric with the nipple and configured to be braced against the pipette housing via a spring, and wherein the spring is configured to be pretensioned by moving the pipette tip onto the nipple so that, when the pipette tip is released from the nipple, the spring relaxes and the third sensing element helps move the pipette tip off of the nipple.

12. The pipette according to claim 1, wherein the curved support is a rotating sleeve having a rotational axis, and wherein at least part of the drive apparatus is positioned within the rotating sleeve.

13. The pipette according to claim 1, wherein the operating element of the ejection apparatus is simultaneously an operating element for driving the drive apparatus.

14. The pipette according to claim 13, wherein the operating element for driving the drive apparatus is configured to be displaced in a longitudinal direction.

15. The pipette according to claim 12, wherein the rotating sleeve comprises parallel cutouts positioned on two diametrically opposite sides, wherein the operating element comprises a laterally projecting operating lever on a support plate, and wherein the support plate comprises a curved slot configured to accommodate a sector of the rotating sleeve and configured to be moved along the sector in a longitudinal direction.

16. The pipette according to claim 15, wherein the pipette housing comprises a first housing slot and a second housing slot, wherein the operating element is configured to be displaced within the first housing slot, and wherein the operating element is configured to be displaced within the second housing slot starting from a middle of the first housing slot and extended in a longitudinal direction such that the operating element is configured to pivot in the first housing slot and is configured to move in a straight line in the second housing slot.

17. The pipette according to claim 15, wherein the rotating sleeve comprises a support ring positioned on one end of the rotating sleeve.

18. The pipette according to claim 1, wherein the pipette housing and the curved support comprise at least one of a magnet assembly and a spring assembly configured to independently displace the operating element into the start position.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is explained below based on the accompanying drawings of an exemplary embodiment. In the drawings:

(2) FIG. 1 illustrates a perspective view of an embodiment of a partially cut-away positive displacement pipette with a pipette tip mounted on the nipple;

(3) FIG. 2 illustrates an enlarged perspective view of an embodiment of a slotted nipple with an inner adjacent locking sleeve of the positive displacement pipette with a mounted pipette tip;

(4) FIG. 3 illustrates a side elevational view of the embodiment of FIG. 2;

(5) FIG. 4 illustrates a cross sectional view of the embodiment of FIG. 2;

(6) FIG. 5 illustrates and exploded view of the embodiment of FIG. 1;

(7) FIG. 6 illustrates an exploded view of the embodiment of FIG. 1 without the pipette housing;

(8) FIG. 7 illustrates a perspective view of an embodiment of a rotating sleeve with the ejection rod and the locking sleeve of the positive displacement pipette in the start position;

(9) FIG. 8 illustrates a partial cut-away of the embodiment of FIG. 7;

(10) FIG. 9 illustrates a partial cut-away of the embodiment of FIG. 7 while in a pipetting position;

(11) FIG. 10 illustrates a partial cut-away of the embodiment of FIG. 7 in an ejecting position; and

(12) FIG. 11 illustrates a cross sectional view of an embodiment of a slotted pipette tip on a nipple of another positive displacement pipette with a locking sleeve lying on the outside of the pipette tip.

(13) In the present application, the expressions “upper” and “lower” as well as “vertical” and “horizontal” and terms derived therefrom such as “above” and “below”, “standing upright” and “upside down” as well as “over each other” refer to an arrangement of the pipette in which the nipple is oriented vertically, and is located on the downwardly facing end of the pipette housing. With regard to the pipette tip, these expressions refer to a vertical orientation of the middle axis of the pipette tip, wherein the tip opening is arranged at the bottom, and the mounting opening is arranged at the top.

DETAILED DESCRIPTION OF THE INVENTION

(14) According to FIG. 1, a pipette 1 configured as a positive displacement pipette has a rod-shaped (e.g. cylindrical) pipette housing 2. From the lower end of the pipette housing 2, a hollow cylindrical shaft 3 projects downward. A nipple 4 projects downward from the lower end of the shaft 3 that, according to FIGS. 1 and 4, has a through-bore 5 with a through-hole in the lower end. The inner diameter of the through-bore 5 is smaller than the inner diameter of the shaft 3.

(15) The nipple 4 has a top nipple section 6 in the shape of a hollow cylinder, and underneath, a lower nipple section 7 in the shape of a hollow cone. An annular groove 8 runs around the outer circumference of the nipple 4 between the upper nipple section 6 and the lower nipple section 7.

(16) The upper nipple section 6, the annular groove 8 and the lower nipple section 7 form a first means for the form-fit connection 9 of the pipette to a pipette tip.

(17) Furthermore, the nipple 4 has two slots 10, 11 running in its longitudinal direction that lie diametrically opposed to each other. The slots 10, 11 extend from the lower end over the entire length of the nipple 4.

(18) According to FIGS. 1, 5 and 6, there is a drive apparatus 12 in the pipette housing 2 that comprises a transmission element 13 in the form of a transmission rod 14, a transmission mechanism 15 and a drive element 16 in the form of a stroke rod 17. Furthermore, the drive apparatus 12 comprises an operating element 18 in the form of an operating lever 19 that is securely connected via a bar 20 to a support plate 21.

(19) According to FIG. 6, the support plate 21 has an oval shape with a wide, rounded end and a narrow rounded end, wherein the operating lever 19 projects from the edge of the narrow rounded end. In addition to this edge, the support plate 21 has a first curved slot 22 that runs approximately parallel to the contour of the narrow rounded end. Furthermore, the support plate 21 has a rectangular, first edge cutout 23 in the middle of the first curved slot 22 on the side of the narrow rounded end.

(20) According to FIGS. 1 and 5, the stroke rod 17 is inserted from above into the shaft 3 and the nipple 4. According to FIG. 4, it is hollow and provided with a longitudinal slot 24 running in a longitudinal direction starting from the lower end. Because of the longitudinal slot 24, the stroke rod 17 has a C-shaped cross-section. Its lower end forms a seat 25 for the upper end of a plunger rod.

(21) The transmission mechanism 15 is configured so that the stroke rod 17 is alternatingly displaced downward and upward during sequential downward displacements of the operating lever 19 between which the operating lever 19 is displaced upward. Consequently, by pressing the operating lever 19 downward, the stroke rod 17 can be displaced out of an upper position into a lower position, the stroke rod 17 retains the lower position during the subsequent upward displacement of the operating lever 19, and the stroke rod 17 is again displaced upward by subsequently pressing the operating lever 19 downward. This can be repeated as frequently as desired.

(22) According to FIGS. 1, 5 and 6, the pipette 1 is provided with an ejection apparatus 26. This comprises a curved support 27 that is rotatably mounted in the pipette housing 2 and is configured as a hollow cylindrical rotating sleeve 28. The rotating sleeve 28 is for example rotatably mounted by its outer circumference on the inner circumference of the pipette housing 2, and the upper and lower ends are braced against ledges of steps on the inner circumference of the pipette housing 2 so that it cannot be displaced in an axial direction in the pipette housing 2. The rotational axis of the rotating sleeve 28 coincides with the longitudinal axis of the pipette housing 2 and the longitudinal axis of the nipple 4.

(23) The rotating sleeve 28 has parallel cutouts 29, 30 on two diametrically opposite sides parallel to its rotational axis which extend from the upper edge of the rotating sleeve 28 and terminate at a distance from their lower edge. Below the cutouts, the rotating sleeve 28 accordingly consists of an annular base 31, and it also consists of two diametrically opposing sectors 32, 33 of an annulus that border the two cutouts 29, 30 on the side.

(24) A first curve 34 and a second curve 35 are arranged on the outer circumference of the annular base 31 of the rotating sleeve 28. The first curve 34 is configured as a first groove 36 in the form of an inverted (upside down) Y. The vertical part 37 of the Y extends far upward to a sector 32 just short of the top edge of the sector 32. The second curve 35 is a second groove 38 in the outer circumference of the base 31 of the rotating sleeve 28 in the form of an upright V. The first curve 34 and the second curve 35 are arranged offset 90° relative to each other on the circumference of the rotating sleeve. The first curve 34 and the second curve 35 each extend over an angular range of less than 90° over the circumference of the rotating sleeve 28.

(25) According to FIGS. 1, 5 and 6, the ejection apparatus 26 comprises an ejection rod 39 that comprises a strip-shaped or flat upper ejection rod part 40 and a cylindrical lower ejection rod part 41. The upper and the lower ejection rod part 40, 41 are parallel to each other and arranged laterally offset to each other. The lower end of the upper ejection rod part 40 is connected to the upper end of the lower ejection rod part 41 by a strip-shaped or flat connecting rod part 42 angled obliquely relative to the two ejection rod parts. A first sensing element 43 in the form of a first guide pin 44 extends at a right angle from the inside of the upper ejection rod part 40. The ejection rod 39 is preferably configured as a single part, for example from a rigid plastic.

(26) According to FIGS. 1, 4 and 7, the ejection rod 39 is guided by the guide pin 44 into the first groove 36, the connecting rod part 42 penetrates the longitudinal slot 24 of the stroke rod 17, and the lower ejection rod part 41 extends within the stroke rod 17 almost up to the lower bottom end thereof.

(27) According to FIGS. 1, 4, 5 and 6, the pipette 1 comprises a locking apparatus 45 that comprises a locking sleeve 46 and a strip-shaped or flat control rod 47 parallel thereto. The upper end of the locking sleeve 46 and the lower end of the control rod 47 are connected to each other by a second connecting rod part 48 that is angled obliquely to the locking sleeve 46 and to the control rod 47. A second sensing element 49 in the form of a second guide pin 49.1 extends from the inside of the control rod 47.

(28) According to FIGS. 1 and 7, the second guide pin 49.1 is guided in the second groove 38. According to FIGS. 1 and 4, the locking sleeve 46 is inserted from above into the shaft 3 and lies against the inner side of the nipple 4. The stroke rod 17 and the ejection rod 39 are inserted from above into the locking sleeve 46.

(29) With the first curved slot 22, the operating element 18 is shoved onto the sector 32 of the rotating sleeve 28 on which the first groove 36 extends. According to FIGS. 1, 6 and 7, the rotating sleeve 28 is connected at the top to a support ring 50 that bridges the two sectors 32, 33 and stabilizes the rotating sleeve 28. On the outer edge, the support ring 50 has a downwardly projecting surface 51 that laterally surrounds the outer edges of the two sectors 32, 33. Furthermore, it has a second curved slot 52 that accommodates the upper edge of the sector 33 which is not provided with a groove 36, 38. On the diametrically opposite side, there is a rectangular second edge cutout 52.1 in the surface 51 that is open at the bottom and is configured to accommodate the bar 20 between operating lever 19 and support plate 21.

(30) The support ring 50 is for example connected to the rotating sleeve 28 by adhesion.

(31) The rotating sleeve 28 and the locking sleeve 46 as well as the operating element 18 are for example made of one or more rigid plastics and/or metal. The rotating sleeve 28, the support ring 50, the operating element 18 and/or the locking sleeve 46 are preferably each configured as a single part. An operating button of the operating element 18 can also be produced from an elastic or soft elastic plastic or rubber.

(32) So that it can be operated from the outside, the operating lever 19 extends out of the pipette housing 2 through a first housing slot running transverse to the longitudinal axis of the pipette housing 2 and extending over a part of the circumference of the pipette housing 2. The first housing slot is connected in the middle to a second housing slot running in the longitudinal direction of the pipette housing 2.

(33) Opposite the effect of a spring apparatus, the operating lever 19 can be displaced downward, starting from the support ring 50, along the second housing slot, wherein it slides with the first curved slot 22 on the sector 32 of the rotating sleeve 28. After being relieved, the spring apparatus independently displaces the operating lever 19 back upward.

(34) A sleeve-shaped third sensing element 53 is guided on the outside of the shaft 3. A spring apparatus in the form of a helical spring 54 guided on the shaft abuts the bottom side of the pipette housing 2 and the top side of the third sensing element 53. By means of the helical spring 54, the sensing element 53 is pressed from above against a stop element on the shaft 3 or the nipple 4.

(35) An adjusting knob 55 for adjusting a metering volume is arranged on the top side of the pipette housing 2. The metering volume can be adjusted by turning the adjusting knob 55. A counter 56 arranged thereunder in the pipette housing 2 indicates the adjusted metering volume in each case. The adjusting knob 55 and/or the counter 56 is coupled to the transmission mechanism 15. The transmission mechanism 15 is configured to change the stroke of the stroke rod 17 corresponding to the particular adjusted metering volume, which stroke is executed by the downward displacement of the operating element 18.

(36) According to FIGS. 1 and 4, a pipette tip 57 is mounted on the nipple 4. The pipette tip 57 comprises a tubular body 58 that has a tip opening 59 in the bottom end, a collar 61 having a mounting opening 60 on the top end, and a seat region 62 on the inner circumference of the collar 61 for clamping onto the nipple 4. The seat region 62 has a contour complementary to the nipple 4 that has a conical, lower seat section 63 at the bottom for accommodating the conical lower nipple section 7, above which is a peripheral bead 64 for engaging in the annular groove 8 of the nipple 4, and above which is a cylindrical upper seat section 65 for accommodating the cylindrical upper nipple section 6. The lower seat section 63, the bead 64, and the upper seat section 65 form second means for the form-fit connection 66 of the pipette tip 57 with the pipette 1.

(37) Below the seat region, 62, the tubular body 58 has a cylindrical plunger travel region 67. Thereunder, the tubular body 58 has a downwardly tapering tip section 68 with the shape of a conical frustum. The tip section 68 is shown in FIG. 4 and is omitted in the other drawings for reasons of simplification. A tip plunger 69 is inserted into the tubular body 58. This comprises a plunger 70 that is guided in the plunger travel region 67. A plunger rod 71 projects upward from the plunger 70 and has a smaller diameter than the plunger 70. At the upper end, the plunger rod 71 has a plunger head 72. According to FIG. 4, the plunger head 72 is pressed downward into the seat 25 of the stroke plunger 17.

(38) According to FIGS. 1 and 8, a pipette tip 57 is held on the pipette 1 in a starting state. The seat region 62 is in particular connected to the nipple 4 in a form-fit by the bead 64 engaging in the annular groove 8. The actuating element 18 is located in the starting position at the upper end of the second housing slot and can be screwed into the first housing slot in both directions. The maximum angle of rotation is limited by the extent of the first and second grooves 36, 38 in the circumferential direction, or the first housing slot depending on which extent is smaller.

(39) The locking sleeve 46 is arranged in the lowest position according to FIG. 4 so that it prevents the pipette tip 57 from unintentionally releasing from the nipple 4. For the form-fit connection to be released, a radial constriction of the nipple 4 would in fact be necessary that the locking sleeve 46 does not permit in this position. In deviation from FIG. 4, the tip plunger 69 in the starting position does not yet press into the seat 25 of the stroke rod 17 with the plunger head 72.

(40) To connect the tip plunger 69 to the stroke rod 17, the operating element 18 is pressed downward. The movement is transmitted by the transmission mechanism 15 to the stroke rod 17 so that it is pressed with the seat 25 onto the plunger head 72. This is shown in FIG. 4.

(41) After being released, the operating element 18 is displaced back into its starting position by a spring apparatus according to FIG. 8. The stroke rod 17 and the tip plunger 69 maintain the positions according to FIG. 4.

(42) To draw liquid, the pipette 1 is immersed in a liquid by the lower end of the pipette tip 57 held thereon. Then the operating element 18 is again pressed downward. This movement is converted by the transmission apparatus 15 into a stroke movement of the stroke rod 17. As a result, the tip plunger 69 is displaced upward. In so doing, the plunger head 72 entrains the ejection rod 39 so that the first guide pin 44 slides upward in the vertical part 37 of the Y-shaped first groove 36. During this, the locking sleeve 46 retains its position. This is shown in FIG. 9.

(43) Once the operating element 18 has executed the set stroke, the pipette tip 57 is filled with a certain quantity of liquid. Then the operating element 18 is relieved and is displaced back upwards by the spring apparatus up to the stop on the support ring 50. To discharge this amount of liquid, the pipette tip 57 of the pipette 1 can be oriented over another vessel. By again pressing the operating element 18 downward, the stroke rod 17 is displaced downward, and the quantity of liquid is discharged. In so doing, the first guide pin 44 slides downward to the node point of the first groove 36.

(44) The stroke executed by the operating element 18 while drawing and discharging liquid depends on the set amount of liquid. Drawing and discharging liquid can occur several times.

(45) To eject the pipette tip 57, the operating lever 18 in the starting position is swung to the right or to the left. This rotates the rotating sleeve 28 so that the second groove 38 displaces the second guide pin 49.1, and therefore the locking sleeve 46, upward until the locking sleeve 46 has released the pin 4 until it can be deformed radially inward. To accomplish this, preferably the locking sleeve 46 is pulled out of the through-bore 5. Furthermore, by rotating the rotating sleeve 28, the first guide pin 44 is displaced downward in one of the two lateral sections of the bottom part of the first groove 36 so that the ejection rod 39 presses against the tip plunger 69 that abuts the tip section 68 at the bottom. In so doing, the bead 64 exerts a radial force on the nipple to constrict it, and the form-fit connection between pipette tip 57 and nipple 4 is released. This releases the pipette tip 57 from the nipple 4. This is shown in FIG. 10. The scraping of the pipette tip 57 off the nipple 4 can be assisted by the sensing element 53 that is pressed by the pretensioned helical spring 54 against the top edge of the pipette tip 57.

(46) Once the used pipette tip 57 is released from the nipple 4, a new pipette tip 57 can be connected to the nipple 4. To accomplish this, the pipette 1 can be inserted with the nipple 4 into the seat opening 68 of a pipette tip 57 provided in a support. In so doing, the sensing element 53 is displaced upward and pretensions the helical spring 54. Furthermore, the plunger head 72 presses against the bottom side of the ejection rod 39 so that the first guide pin 44 slides up to the first branching point of the first groove 36. In so doing, the rotating sleeve 28 is rotated in the pipette housing 2 until the operating element 18 is located in the starting position. At the same time, the second guide pin 49.1 slides in the second groove 38 to the low point. This displaces the locking sleeve 46 into the locked position in FIG. 4 in which it prevents the pipette tip 57 from releasing from the nipple 4. Connecting the tip plunger 69 to the stroke rod 17 and pipetting can be carried out in the above-described manner.

(47) The exemplary embodiment in FIG. 1 differs from that described above in that the locking sleeve 46 is shoved in the locked position beyond the outer circumference of the collar 61 of the pipette tip 57. With this positive displacement pipette, pipette tips 57 are used that have at least one longitudinal slot proceeding from the upper end. The longitudinal slot enables a radial expansion of the pipette tip 57 in order to establish the form-fit connection of the pipette tip 57 with the nipple 4. The form-fit connection is prevented from releasing when the locking sleeve 57 is located in the locked position as shown in FIG. 11. To release the pipette tip 57 from the nipple 4, the locking sleeve 46 is displaced upward by means of the rotating sleeve 28 as in the above-described exemplary embodiment, and then the pipette tip 57 is released from the nipple 4 by pressing against the top side of the tip plunger 69.

REFERENCE SIGN LIST

(48) 1. Pipette 2. Pipette housing 3. Shaft 4. Nipple 5. Through-bore 6. Upper nipple section 7. Lower nipple section 8. Annular groove 9. First means for a form-fit connection 10. Slot 11. Slot 12. Drive apparatus 13. Transmission element 14. Transmission rod 15. Transmission mechanism 16. Drive element 17. Stroke rod 18. Operating element 19. Operating lever 20. Bar 21. Support plate 22. First curved slot 23. First edge cutout 24. Longitudinal slot 25. Seat 26. Ejection apparatus 27. Curved support 28. Rotating sleeve 29. Cutout 30. Cutout 31. Base 32. Sector 33. Sector 34. First curve 35. Second curve 36. First groove 37. Vertical part 38. Second groove 39. Ejection rod 40. Upper ejection rod part 41. Lower ejection rod part 42. Connecting rod part 43. First sensing element 44. Guide pin 45. Locking apparatus 46. Locking sleeve 47. Control rod 48. Second connecting rod part 49. Second sensing element 49.1 Second guide pin 50. Support ring 51. Surface 52. Second curved slot 52.1 Second edge cutout 53. Third sensing element 54. Helical spring 55. Adjusting knob 56. Counter 57. Pipette tip 58. Body 59. Tip opening 60. Mounting opening 61. Collar 62. Seat region 63. Lower seat section 64. Bead 65. Upper seat section 66. Second means for a form-fit connection 67. Plunger travel region 68. Tip section 69. Tip plunger 70. Plunger 71. Plunger rod 72. Plunger head