PIPETTING HEAD, PIPETTING DEVICE COMPRISING A PIPETTING HEAD, AND METHOD FOR PIPETTING USING A PIPETTING HEAD

Abstract

A pipetting head comprises a carrier, at least one attachment held on the carrier and configured to secure at least one pipette tip, and two O-rings retained on the at least one attachment and configured to contact the sealing seat of the at least one pipette tip. The inner diameter of the sealing seat of the at least one pipette tip is smaller than an outer diameter of a respective O-ring where the sealing seat contacts a respective O-ring. The respective O-ring is deformed while the pipette tip is slid onto the at least one attachment to securely clamp the at least one pipette tip. The sealing seat of the at least one pipette tip is dimensioned such that the at least one attachment exerts a force on the pipette tip to deform the at least one pipette tip when it is securely clamped on the at least one attachment.

Claims

1-16. (canceled)

17. A pipetting head with at least one pipette tip for a pipetting device, the pipetting head comprising: a carrier; at least one attachment held on the carrier and configured to receive and secure the at least one pipette tip, wherein the at least one pipette tip comprises a sealing seat defining an inner diameter; and two O-rings retained on the at least one attachment and configured to contact the sealing seat of the at least one pipette tip, wherein the inner diameter of a sealing seat of the at least one pipette tip is smaller than an outer diameter of a respective O-ring where the sealing seat contacts a respective O-ring such that the respective O-ring is deformed while the at least one pipette tip is slid onto the at least one attachment to securely clamp the at least one pipette tip on the at least one attachment, and wherein the sealing seat of the at least one pipette tip is dimensioned such that the at least one attachment exerts a force on the at least one pipette tip when the sealing seat contacts the at least one attachment, and wherein the force is configured to deform the at least one pipette tip when the at least one pipette tip is securely clamped on the at least one attachment.

18. The pipetting head according to claim 17, wherein the two O-rings are comprised of an elastomeric material.

19. The pipetting head according to claim 18, wherein the elastomeric material is one of a soft rubber, silicone, and a thermoplastic elastomer.

20. The pipetting head according to claim 18, wherein the at least one attachment comprises apparatuses configured for axial position securing and to support one of the two O-rings in a top position and another of the two O-rings in a bottom position, and wherein the apparatuses configured for axial position securing enable deformation of the two O-rings in a radial direction.

21. The pipetting head according to claim 20, wherein the apparatuses configured for axial position securing are peripheral annular grooves defined on a perimeter of the at least one attachment and are configured to partially accommodate at least one of the two O-ring.

22. The pipetting head according to claim 20, wherein the apparatuses configured for axial position securing are one or more projections on a perimeter of the at least one attachment configured to at least partially accommodate at least one of the two O-ring between them.

23. The pipetting head according to claim 17, wherein the at least one attachment comprises at least one conical portion and at least one cylindrical portion.

24. The pipetting head according to claim 22 wherein the at least one attachment further comprises: a top cylindrical portion positioned at a top end of the at least one attachment; a bottom cylindrical portion positioned at a bottom end of the at least one attachment; a conical portion position between the top and bottom cylindrical portions; top apparatuses configured for axial position securing positioned between the top cylindrical portion and the conical portion (19); and bottom apparatuses configured for axial position securing between the conical portion and the bottom cylindrical portion.

25. The pipetting head according to claim 24, wherein the conical portion tapers from the top cylindrical portion to the bottom cylindrical portion.

26. The pipetting head according to claim 17, wherein one of the two O-rings comprises at least one of: (1) a larger inner diameter than another of the two O-rings; and (2) a cross-section with a larger diameter than the other of the two O-rings.

27. The pipetting head according to claim 20, wherein a first of the two O-rings is positioned towards a top of the attachment and a second of the two O-rings is positioned towards a bottom of the attachment relative to the first O-ring, wherein at least one of: (1) a diameter of a cross-section of the first O-ring is larger than a depth of a top annular groove; (2) a width of the top annular groove is at least a same size as the diameter of the cross-section of the top O-ring; (3) a diameter of a cross-section of the second O-ring is larger than a height of a bottom annular groove; and (4) a width of the bottom annular groove is at least a same size as the diameter of the cross-section of the bottom O-ring.

28. The pipetting head according to claim 17, wherein the attachments are arranged parallel and adjacent to each other in one or more rows.

29. The pipetting head according to claim 17, wherein the attachments are securely connected to the carrier.

30. A method for using a pipetting head, the method comprising: clamping a plurality of pipette tips onto a plurality of attachments of the pipetting head; shifting the pipetting head until a bottom end of each of the plurality of pipette tips contacts a vessel positioned on a work surface; shifting the pipetting head until the bottom end of each of the plurality of pipette tips is a specific distance away from a floor of the vessel; and drawing liquid from the vessel into each of the plurality of pipette tips.

31. The method according to claim 30, wherein the pipetting head is shifted until the bottom end of each of the plurality of pipette tips contacts the floor of the vessel at a same time, and wherein the pipetting head is then shifted until the bottom end of each of the plurality of pipette tip is a specific distance from the floor of the vessel.

32. The method according to claim 30, wherein the pipetting head is a multichannel pipetting head and the vessel is a microtiter plate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0060] The invention will be further explained below with reference to the accompanying drawings of exemplary embodiments. In the drawings:

[0061] FIG. 1 illustrates a front view of an embodiment of a pipetting head with clamped-on pipette tips;

[0062] FIG. 2 illustrates a rear view of the embodiment of the pipetting head from FIG. 1 without pipette tips;

[0063] FIG. 3 illustrates a sectional view of the embodiment of the pipetting head from FIG. 1;

[0064] FIG. 4 illustrates an enlarged sectional view of an embodiment of an attachment of the pipetting head of FIG. 1:

[0065] FIG. 5 illustrates a diagram of mounting forces as a function of the path of the pipetting head when clamping onto a conventional pipetting head and onto a pipetting head;

[0066] FIG. 6 illustrates a schematic depiction of tolerance chains and sums in a metering system;

[0067] FIG. 7 illustrates a schematic depiction of an embodiment of attachments of a multichannel pipetting head with picked-up pipette tips above the floor of a microtiter plate;

[0068] FIG. 8 illustrates a schematic depiction of an embodiment of the pipetting tool with pipette tips individually adjusted through making contact with the floor region of the microtiter plate; and

[0069] FIG. 9 illustrates a schematic depiction of an embodiment of the pipetting tool with individually adjusted pipette tips retracted to a small distance from the floor region of the microtiter plate.

DETAILED DESCRIPTION OF THE INVENTION

[0070] In this application, the terms “top” and “bottom,” “horizontal” and “vertical” refer to an orientation of the pipetting head with the attachments in a vertical direction, wherein the attachments are arranged at the bottom and the other parts of the pipetting head are arranged above. In the description of different embodiments, the same reference numbers are used for components with the same names.

[0071] According to FIGS. 1 to 2, the pipetting head 1 comprises a housing 2 that is formed from a front and a rear housing shell 3, 4 that are joined in a vertical plane. Eight parallel attachments 5 (pins) for clamping on pipette tips 6 project vertically downward from the underside of the pipetting head 1 (FIGS. 3 and 4). A strip-shaped carrier plate 7 is arranged on the top side of the housing 2. From the carrier plate 7, a fastening pin 8 projects upward.

[0072] According to FIG. 3, eight parallel plunger/cylinder units 9 are arranged next to each other in a row in the pipetting head 1. Each plunger/cylinder unit 9 has one cylinder 10 in which a plunger 11 is movably arranged. Each cylinder 10 has an outer thread 12 with which it is screwed into a corresponding inner thread 13 in a through-hole 14 in a horizontal bottom housing wall 15. Screwing the cylinders 10 into the bottom housing wall 15 is limited by steps 16 on the outer perimeter of the cylinders 10 with which they lie against the top side of the bottom housing wall 15. The bottom part of the cylinders 10 projects outwardly from the underside of the bottom housing wall 15 and forms the attachments 5 there. Housing 2 is thus a carrier for the attachments 5.

[0073] According to FIG. 4, each attachment 5 has a top cylindrical portion 17 at the top, a bottom cylindrical portion 18 at the bottom, and a conical portion 19 tapering from top to bottom between them. On each attachment 5, top apparatuses for axial position securing 20 in the form of a top annular groove 21 are present between the top cylindrical portion 17 and the conical portion 19, and bottom apparatuses for axial position securing 22 in the form of a bottom annular groove 23 are present between the conical portion 19 and the bottom cylindrical portion 18.

[0074] An O-ring 24, 25 made of an elastomer, preferably a soft elastomer, in particular a soft silicone rubber, is inserted into each annular groove 21, 23. Each O-ring 24, 25 is guided on the base of the annular groove 21, 23 and has a cross-section with a diameter that is larger than the depth of the annular groove 21, 23 and that is smaller than the width of the annular groove 21, 23 in which it is arranged. The interior space 26 of each cylinder 10 into which the plunger 11 is plunged from above extends downward to a connecting hole 27 in the bottom face of the attachment 5.

[0075] At the top of each cylinder 10, a liner 28 (FIG. 3) is arranged, through which a plunger 11 is guided into each cylinder 10 in a sealing manner. Referring back to FIG. 3, each plunger 11 is configured as a cylindrical rod which is inserted at the top into a central hole 29 of a cylindrical plunger head 30 and is fastened therein (e.g. adhered or pressed in). Each plunger head 30 has a peripheral plunger head annular groove 31 on the outer perimeter. Below a horizontal top housing wall 32, a strip-shaped plunger plate 33 is arranged parallel thereto. The plunger plate 33 has eight channels 34 on the underside that are open at the bottom and are aligned parallel to each other. Each channel is bordered by two strip-shaped channel walls 35 and by two channel shoulders 36 that project to the inside from the bottom ends of the channel walls. The channel walls 35 on the two outer edges of the plunger plate 33 each border an adjacent channel 34 only on one side. The other channel walls 35 each border two adjacent channels 34 on one side. Between the channel shoulders 36, each channel has one slotted opening 37 on the underside of the plunger plate 33. On the edges of the plunger plate 33 that are aligned parallel to the front side and rear side of the housing 2, the channels 34 have face openings 38. Top portions of the plunger heads 30 are inserted into the channels 34 through the face openings 38 so that the channel shoulders 36 engage the plunger head annular grooves 31 in a form fit. Consequently, the plungers 11 can be shifted together in the cylinders by vertically shifting the plunger plate 33.

[0076] In the center of the fastening pin 8, an axially shiftable threaded nut 39 is arranged, the bottom end of which is securely connected to the plunger plate 33 in order to shift the plunger plate 33 in the axial direction of the cylinders 10. The fastening pin 8 has a cylindrical top pin portion 40 at the top. On the outer perimeter, the top pin portion 40 bears two partially peripheral connecting elements 41 that are offset to each other by 180° and project radially to the outside and with which a bayonet connection can be formed. The connecting elements 41 have a slight thread pitch at the bottom side to be tightened with a fitting connecting element in a pin holder of a bayonet connection.

[0077] Adjacent to the top pin portion 40, the fastening portion 8 has a cylindrical, middle pin portion 42 with a larger outer diameter than the top pin portion 40. Underneath, the fastening pin 8 has a bottom pin portion 43 that expands conically downward. The bottom pin portion 43 is connected securely at its base to the carrier plate 7. A central hole 44 extends in the longitudinal direction of the fastening pin 8. Said hole has two diametrically opposed longitudinal grooves 45.

[0078] The sleeve-like threaded nut 39 is inserted in the central hole 44 and is guided by two radially projecting wings 46 at its top end in the longitudinal grooves 45. Furthermore, a spindle 47 is screwed into the threaded nut 39. Above its thread 48, said spindle has a projecting bearing pin 49 by which it is mounted in a ball bearing 50. The ball bearing 50 is held in a bearing bushing 51 of a bearing carrier 52 that has two tabs that project diametrically from the sides and lie on the top edge of the top pin portion 40 and are fixed thereto by means of screws. On the part of the bearing pin 49 that projects beyond the ball bearing 50, a driver 54 is fixed non-rotatably by means of a radial threaded pin 53 and has a slot 55 extending radially and axially in its top face for introducing a pawl-like drive unit. The spindle 47 is supported on the bottom face of the ball bearing 50. The driver 54 is supported on the top face of the ball bearing 50. The spindle 47 is held hereby in the fastening pin 8 so as to not be axially shiftable. In one wing 46 of the threaded nut 39, a cylinder pin 56 is fixed that is guided through a groove in the bearing carrier 52 oriented parallel to the middle axis of the threaded nut 39 and projects upward out of the fastening pin 8.

[0079] By rotating the driver 54, the spindle 47 that is axially fixed in the fastening pin 8 moves the threaded nut 39 that is non-rotatably guided in the fastening pin 8 in an axial direction. This shifts the plunger plate 33 and the plungers 11 are shifted in the cylinders 10. By rotating the driver 54 in different directions, the plungers 11 can be shifted in different directions in the cylinders 10. By scanning the position of the cylinder pin 56, it is possible to determine the respective position of the plungers 11 in the cylinders 10.

[0080] The fastening pin 8 and the drive integrated therein with the threaded nut 39 and spindle 47 correspond to the embodiments in FIGS. 1 to 4 as well as FIG. 6 according to EP 1 407 861 B1. In this regard, reference is made to the document EP 1 407 861 B1, the content of which is hereby incorporated by reference into this application.

[0081] A laboratory machine is provided with a complementary pin holder of a bayonet connection that is connectable to the fastening pin. Preferably, the complementary connecting part of the laboratory machine corresponds to the tool holder according to FIGS. 7 to 10 of EP 1 407 861 B1. In this regard, reference is made to the document EP 1 407 861 B1, the content of which is hereby incorporated by reference into this application.

[0082] Below the bottom housing wall 15, a stripping plate 57 is arranged that has further through-holes 58 through which the pins 5 project downward. The stripping plate 57 is connected on a longitudinal side to a rod assembly 59 which is guided upward in a convexity 60 of the rear housing shell 4 which has an opening at the top through which the rod assembly 59 protrudes out of the housing 2. A driver 61 (FIG. 2) projects laterally from the top end of the rod assembly 59. By means of a spring apparatus (not shown), the rod assembly 59 is pressed upward in the resting state until the stripping plate 57 lies against the underside of the bottom housing wall 15. The laboratory machine has a drive with a drive element with which the driver 61 (FIG. 2) can be pressed downward, as a result of which the stripping plate 57 is entrained downward to strip the pipette tips 6 from the attachments 5.

[0083] According to FIGS. 3 and 4, pipette tips 6 are clamped onto the attachments 5. The pipette tips 6 are tubes with a tip opening 62 at the bottom end 63 and a mounting opening 64 at the top end 65. The inner diameter and the outer diameter of the pipette tip 6 generally expand from the tip opening 62 to the mounting opening 64. In the example, the pipette tips 6 have several conical regions 64, 65, 66 as well as a cylindrical expansion 67 in the proximity of the top end 65. In the region of the cylindrical expansion 67 and in the region beneath it, the pipette tip has a sealing seat 68 in the interior.

[0084] According to FIGS. 3 and 4, the attachments 5 of the pipetting head 1 are introduced through the mounting openings 64 into the pipette tips 6. The O-rings 24, 25 are arranged at the height of the sealing seat 68. This presses together the O-rings 24, 25 somewhat in the radial direction so that the pipette tips 6 securely clamp on the attachments 5 and are sealed against the attachments 5. Since the O-rings 24, 25 consist of a soft-clastic material and the pipette tips 6 otherwise have no contact with the attachments 5, the mounting forces when mounting the pipette tips 6 on the attachments 5 are relatively small.

[0085] In FIG. 5, the measured mounting forces when mounting pipette tips as a function of the path of the pipetting head are shown next to each other for a pipetting head 1 according to the invention with eight channels and two O-rings 24, 25 on each attachment 5 and a conventional pipetting head with eight channels without O-rings 24, 25 on the attachments. According to the three curves on the left in the diagram, when using a conventional pipetting head, the mounting forces increase sharply until they are sitting on the attachments in a sufficiently secure and sealing manner. This is given at a mounting force of 120 Newton and with a shift of the pipetting head of 2.2 mm. According to the curves plotted on the right in the diagram, a sufficiently secure and sealed connection is established at mounting forces of approx. 30 Newtons and a shift of the pipetting head of 2 mm. In this case, only the O-rings 24, 25 are elastically deformed. Above this value, the mounting forces increase sharply since a deformation of the pipette tips 6 is also required for this. Due to the reduced mounting forces, the forces for ejecting the pipette tips 6 from the attachments 5 are also reduced.

[0086] In the following, the use according to the invention will be explained on the basis of FIGS. 6 to 9. According to FIG. 6, a laboratory machine 70 has a plurality of tolerances which influence the positioning of the tip opening 64 of pipette tips 6 in the vertical direction. These tolerances include the tolerances of the positioning of a multi-axis transferring device 71 (robot arm or other transferring system). Added to these are the tolerances of fixing a pipetting head 1 (pipetting tool) in the tool holder 72 held on the multi-axis transferring device 71. Furthermore, manufacturing tolerances of the pipetting head 1 must also be taken into account. In addition, the attachments 5 for picking up the pipette tips 6 and the pipette tips 6 themselves have tolerances. Microtiter plates 73 and adapters 74 for positioning the microtiter plates 73 on a work surface 75 (deck) of the laboratory machine 70 have additional tolerances. Finally, the work surface 75 itself also has tolerances.

[0087] In particular when using multichannel pipetting heads 1, the exact positioning of the individual pipette tips 6 is not possible since an equal height must be used for all the pipette tips 6. In many target applications, such as for example next-generation sequencing (NGS), this leads to losses in quality due to decreased efficiency of the washing steps and/or decreased yields from test material. In the worst case, contamination is carried over, e.g., if a sample is to be aspirated below another phase (e.g. samples covered with oil) and portions of the overlay are carried over.

[0088] The reduction of tolerance ranges leads to lower process reliability and therefore to an increased risk of sample loss. In addition, it only partially solves the problem, since specific tolerance ranges must not be undershot. Often, the direct need for a very precise calibration of the device in order to minimize individual tolerances also increases.

[0089] “Surface teaching” addresses specific tolerances on the system (e.g., positioning offset and tool tolerance), but it is very work-intensive for the user and requires a large amount of effort. Additionally, a plurality of tolerances are also not covered by surface teaching (e.g., well geometry, microtiter plate seat on adapter, pipette tip geometry, pipette tip seat, tool holder, etc.), since these do not take place during the metering process but in advance of use.

[0090] The use of two O-rings 24, 25 on each attachment 5 enables unknown tolerance chains due to small differences in the seat of the pipette tips to be allowed while keeping the metering quality the same. The method consists of three substeps: (1) Several pipette tips 6 are picked up on a single- or multichannel pipetting head 1 (FIG. 7); (2) After the pipette tips 6 have been picked up on the attachments 5 of the pipetting head 1, all the pipette tips 6 are located at a comparable height and can be slid an additional distance onto the attachments 5 with a small exertion of force; and (3) Through a dedicated movement in the vertical direction under the floor tolerance range of a surface (e.g., the floor of a microtiter plate 73), the pipette tips 6 are pressed onto the respective attachments 5 to different extents. With the same alignment of the attachments 5 in the vertical direction, after this step the individual pipette tips 6 have individual heights, which have been determined by the unknown floor geometry and the tolerance chains. This is shown in FIG. 8.

[0091] After that, a small upward movement of the pipetting head 1 generates a gap x between the bottom ends 63 of the pipette tips 6 and the surface of the vessel (e.g., microtiter plate 73). This gap x is required for aspiration of liquid into the pipette tips 6 to avoid blocking the pipette tips 6. According to this method, due to the individual positioning of the pipette tips 6, the bottom ends of all the pipette tips 6 are the same distance from the surface of the vessel. This is shown in FIG. 9.

[0092] The advantage of this method is that all (known and unknown) tolerances can be completely compensated at each metering step. Furthermore, this process takes place automatically, since it can be executed by the laboratory machine 70 without additional effort for the user. The method is performed during a run of the laboratory machine 70 with the individual combinations of pipette tips 6 and the corresponding individual cavities of single- and multi-cavity vessels used (e.g., microtiter plates 73).

LIST OF REFERENCE SIGNS

[0093] 1 Pipetting head [0094] 2 Housing (carrier) [0095] 3,4 Housing shell [0096] 5 Attachment (pin) [0097] 6 Pipette tip [0098] 7 Fastening plate (carrier plate) [0099] 8 Fastening pin [0100] 9 Plunger/cylinder unit [0101] 10 Cylinder [0102] 11 Plunger [0103] 12 Outer thread [0104] 13 Inner thread [0105] 14 Through-hole [0106] 15 Housing wall [0107] 16 Step [0108] 17 Top cylindrical portion [0109] 18 Bottom cylindrical portion [0110] 19 Conical portion [0111] 20 Top apparatuses for axial position securing [0112] 21 Top annular groove [0113] 22 Bottom apparatuses for axial position securing [0114] 23 Bottom annular groove [0115] 24, 25 O-rings [0116] 26 Interior space [0117] 27 Connecting hole [0118] 28 Liner [0119] 29 Hole [0120] 30 Cylindrical plunger head [0121] 31 Plunger head annular groove [0122] 32 Housing wall [0123] 33 Plunger plate [0124] 34 Channels [0125] 35 Channel wall [0126] 36 Channel shoulder [0127] 37 Slotted opening [0128] 38 Face opening [0129] 39 Threaded nut [0130] 40 Top pin portion [0131] 41 Connecting element [0132] 42 Middle pin portion [0133] 43 Bottom pin portion [0134] 44 Hole [0135] 45 Longitudinal groove [0136] 46 Wing [0137] 47 Spindle [0138] 48 Thread [0139] 49 Bearing pin [0140] 50 Ball bearing [0141] 51 Bearing bushing [0142] 52 Bearing carrier [0143] 53 Threaded pin [0144] 54 Driver [0145] 55 Slot [0146] 56 Cylindrical pin [0147] 57 Stripping plate [0148] 58 Through-hole [0149] 59 Rod assembly [0150] 60 Protrusion [0151] 61 Driver [0152] 62 rip opening [0153] 63 Bottom end [0154] 64 Mounting opening [0155] 65 Top end [0156] 64, 65, 66 Conical regions [0157] 67 Cylindrical expansion [0158] 68 Scaling seat [0159] 70 Laboratory machine [0160] 71 Multi-axis transferring device (robot arm) [0161] 72 Tool holder [0162] 73 Microtiter plate [0163] 74 Adapter [0164] 75 Work surface