WO2002016036A2 - Pipetting head for a robot comprising a number of pipette tips - Google Patents

Abstract

The invention relates to a pipetting head (1) for a robot. Said pipetting head (1) is provided with a number of pipette tips (22) and comprises a connecting part (6), which can be rigidly fastened to a robot arm. The pipetting head also comprises a pipette part (3) to which a number of pipetting tips (22) can be fastened. The pipette part (3) and the connection part (6) are coupled to one another with play in such a manner the pipette part (3) can be actuated in the range of play by means of a separate actuating device (29). The play enables the pipette part to be pressed into several pipette tips (22) by the actuating device (29), whereby the pressing-in process is mechanically decoupled from the robot arm.

Description

 Pipetting head for a robot with several pipette tips

The present invention relates to a pipetting head for a robot, the pipetting head being provided with a plurality of pipette tips.

A robot for carrying out chemical and / or biological reactions is known from WO 99/26070. This robot has a work surface over which a vertically aligned robot arm can be moved in all three dimensions. The robot arm can pick up a disposable pipette tip and wipe it off using a wiper device.

WO 99/26723 describes a pipetting head which can hold several pipette tips. A stripping device is integrated in the pipetting head. The stripping device is driven by a motor via screws, so that it is designed to be movable relative to the remaining area of the pipetting head. The screws form a rigid mechanical connection between the stripping device and the rest of the pipetting head.

DE 31 01 696 A1 discloses a device with a sampling cannula that can be moved in a vertical plane. This sampling cannula can be moved horizontally and vertically within a vertical plane. DE 198 35 833 A1 describes a rigid dosing station with pipettes and pipette tips built into a dosing head. The individual pipettes are spring-loaded so that when pipette tips are picked up, they can act on the pipettes against a spring force.

EP 0 514 948 A1 describes a device in which a pipette holder can be moved in a vertical plane by means of a displacement device. Pipette tips are attached to these by feeding them from below to the holder. The pipette tips can be stripped off by means of a stripping device. The force used to attach or strip off the pipette tip is absorbed by a separate device, the clip-on or wiper device. This push-on or stripping device acts on the adapters for receiving the detachable pipette tips.

US Pat. No. 5,273,717 describes a checking device with which it is determined whether a pipette tip is correctly picked up by a pipette tip receiver. This checking device is provided on a pipette holder, which is provided with an integrated drive device for moving a housing for receiving and stripping pipette tips.

US 4,478,094 and US 5,497,670 each describe a system for handling liquid samples, these systems being provided with strippable pipette tips.

DD 282 082 A5 describes a device for distributing sample liquids. This device has strippable pipette tips that can be stripped by means of a stripping comb.

The invention has for its object to provide a pipette head with which several pipette tips can be picked up, whereby the accuracy and reliability of the robot should not be adversely affected. To achieve this object, the invention has the features specified in claim 1. Advantageous refinements of this are specified in the further claims.

According to the invention, a pipetting head for a robot is provided. The pipetting head is provided with a plurality of pipette tips and it has a connecting part which can be rigidly attached to a robot arm and a pipette part to which a plurality of pipette tips can be attached. The pipette part and the connecting part are coupled to one another with a movement play in such a way that the pipette part can be actuated in the region of the movement play by means of a separate actuating device.

The pipette head according to the invention permits the simultaneous handling of several pipette tips without the robotic arm being loaded excessively. Excessive stress on the robot arm would result in inaccurate movement of the robot arm, which can cause the entire robot to malfunction. Such a load is avoided in that the insertion of the pipette tips is mechanically decoupled from the robot arm by the movement play between the connecting part and the pipette part.

The invention is explained below with reference to the embodiment shown in the drawings. These show in:

1 is a perspective view of a pipetting head and a combined actuating and stripping device, the pipetting head being arranged in the region of the actuating device,

2 shows a section through the actuating device from FIG. 1 looking towards the pipetting head,

3 shows the pipetting head from FIGS. 1 and 2 without pipette tips in section, 4 shows the pipetting head from FIG. 1 and the combined actuating and stripping device from FIG. 1 in a perspective view, the pipetting head being arranged in the region of the stripping device, and

5 shows the arrangement from FIG. 4 with a view of the stripping device.

The pipetting head 1 according to the invention is intended for use in a robot for carrying out chemical and / or biological reactions. The pipetting head 1 has a connecting part 2 and a pipette part 3 (FIGS. 1 to 3).

The connecting part 2 is a somewhat elongated approximately cuboid metal body which is arranged horizontally in the robot with its longitudinal extension. A groove 4 is made on the underside of the connecting part, the depth of which corresponds to approximately half the height of the connecting part 2. Approximately in the longitudinal center of the connecting part 2, two bores 5 are formed for receiving connecting pins 6 (FIG. 3). Threaded bores 7 are introduced transversely to these bores 5 in order to receive clamping screws for fixing the connecting pins 6 (FIG. 2). The connecting pins 6 are part of a vertically aligned robot arm which is designed to be movable in all three dimensions (X, Y and Z directions) in a manner known per se.

The connecting part 2 thus serves to rigidly attach the pipetting head 1 to a robot arm.

At the end regions of the connecting part 2, a bore 8 is made in each case, which extend from the top of the connecting part 2 to the bottom of the groove 4. Countersunk bores 9, 10 are formed coaxially to the bores 8 on the upper side of the connecting part 2 as well as on the bottom of the groove 4.

These bores 8 serve to hold the pipette part 3. The pipette part 3 is designed as a rectangular frame, which is composed of an inverted U-shaped support 11 and two connecting struts 13, 14 extending between the free ends 12 of the U-shaped support 11 is. The two struts 13, 14 run parallel to each other with a distance of approx. 1 to 2 cm. The lower strut 14 is attached to the end faces of the free ends of the U-shaped carrier and extends laterally a little beyond the U-shaped carrier, whereby two projections 15 are formed, which serve as engagement elements, as will be explained in more detail below.

Guide bores 16, 17 are respectively made in the two struts 13, 14. The guide holes 17 of the lower strut 14 are provided on the top of the strut 14 with countersunk holes 18.

A pipette adapter 19 extends through one of the guide bores 17 of the lower strut 14 and one of the guide bores 16 of the upper strut 13. The pipette adapters 19 have a vertical through-bore 20 and have an annular web 21 approximately in the longitudinal center, which goes into the counterbore 18 of the lower Brace 14 fits so that the pipette adapters 19 are secured against falling out of the guide bores 16, 17. The region of the pipette adapter 19 which extends downward from the ring web 21 is tapered in a stepped manner in order to accommodate pipette tips 22. In this area, the pipette adapters 19 are provided with a narrow, ring-shaped groove 23 for receiving a sealing element. The area of the pipette adapter 19 which extends upward from the ring web 21 is essentially cylindrical, the circumference of the cylinder corresponding to the diameter of the bores 16 of the upper struts 13. At the upper end area, the pipette adapters 19 have a tubular extension 24, to which a hose is attached, which is not shown in the drawings for the sake of simplicity. The tubes of the individual pipette adapters 19 lead to one or more pump devices with which pipetting can be carried out automatically.

The individual pipette adapters 19 are vertically displaceably mounted in the struts 13, 14, a coil spring 25 being arranged in each case between the upper strut 13 and the ring webs 21. The pipette adapter 19 can thus be moved a little upwards against the action of the coil spring 25. To connect the frame-shaped pipette part 3 to the connecting part 2, two blind holes 26 are formed on the upper side of the U-shaped carrier 11, which are aligned with the holes 8 of the connecting part 2. The lower region of the blind hole 26 is designed as a threaded section and a countersunk hole is introduced above this threaded section. The pipette part 3 is fastened by means of two screws 27 which extend through the bores 8 of the connecting part and are screwed into the threaded section of the blind bores 26. The length of the screws is dimensioned such that a distance d of approximately 1 to 2 cm is formed between the pipette part 3 and the connecting part 2 in the case of screw heads lying in the counterbores 9. In the intermediate area between the bottom of the groove 4 and the top of the pipette part 3, coil springs 28 are arranged around the screws 27. The coil springs 28 are found with their end regions in countersunk holes.

The distance d between the connecting part 2 and the pipette part 3 forms a play of movement, since the pipette part 3 can be displaced into the groove 4 against the action of the coil springs 28, the screw heads of the screws 27 lifting off from the counterbores 9. This movement play serves to mechanically decouple the movement of the pipette part 3 from the connecting part 2.

The pipetting head 1 explained above is used on a robot in combination with an actuating device 29 and a stripping device 30. In the exemplary embodiment discussed below, the actuating device 29 and the stripping device 30 are designed as a combined actuating and stripping device 29, 30 (FIG. 1, FIG. 4).

The actuating device 29 has a base plate 31 which can be fastened to the working surface of a robot. Two vertical end walls 32, 33 are attached to the base plate 31. A receiving device 34 for receiving a plurality of pipette tips 22 is arranged on the base plate 31 in the region between the end walls 32, 33. The receiving device 34 has bores arranged in a grid, in which the pipette tips 22 can be inserted with their tapering and pointed ends pointing downward. The end walls 32, 33 extend upwards into an area above the receiving device 34, in particular into an area above the upper ends of the pipette tips 22 inserted into the receiving device 34. Two pivoting elements 35 extend between the end walls 32, 33. These pivoting elements 35 are each composed of a bearing rod 36 and an operating rod 37. The bearing rods 36 are rotatably mounted in corresponding openings in the end walls 32, 33, the openings being located at the corner regions of the end walls 32, 33 which are remote from the base plate 31. The bearing rod 36 and the actuating rod 37 are each connected by two cam-shaped pivot levers 38 such that the actuating rod 37 arranged parallel to the bearing rod 36 can be pivoted about the bearing rod 36. The distance between the bearing rod 36 and the actuating rod 37 is approximately 1 to 2 cm. The swivel range of the swivel elements 35 is each limited by a vertical stop 39 and a horizontal stop 40. The vertical stop 39 is arranged outside the pivot elements 35 with respect to the receiving device 34 in such a way that the actuating rod 37 strikes the vertical stop 39 when it is located directly above the bearing rod 36 (FIGS. 1, 2). The horizontal stop 40 is arranged in the area under the pivot levers 38, so that the pivot levers 38 strike during a pivoting movement from the vertical position into a pivoting movement directed downwards and inwards towards the receiving device 34 when the actuating rod 37 is located a little below the bearing rod 36 is arranged.

A gear 41 is each concentrically attached to the two bearing rods 36, each of which is wrapped by a toothed belt 42, which is driven by an electric motor 43. The electric motors are simple direct current motors which are controlled by a control device (not shown) in such a way that the pivoting elements 35 are pivoted back and forth between the two end positions (vertical position and position pivoted horizontally inwards). The end positions are determined by the detection of the drive current of the electric motors, the further energy supply being terminated when an end position is reached. The end wall 32 has at its upper edge two recesses 44 through which the actuating rods 37 extend, the recesses 44 being shaped such that the actuating rods 37 can be pivoted freely in the pivoting range explained above. The actuating rods each have a ball or roller bearing 45 on their portions projecting from the end walls 32.

These ball bearings 45 engage in fork-shaped recesses 46 of a scraper comb 47. The scraper comb 47 is a plate-shaped body, on which the fork-shaped recesses 46 project laterally, and which extends across the width of the end wall 32. It has several scraper teeth 48, which are arranged in a horizontal row. The distance between two adjacent scraper teeth 48 is slightly larger than the diameter of the pipette adapter 19 and a bit smaller than the maximum diameter of the pipette tips 22. The scraper comb 47 is arranged with its scraper teeth 48 away from the end wall 32. On the side opposite the scraper 48, the scraper comb 47 has a vertically running guide rail 49 with roller bearings 49a. The guide rail engages in a corresponding groove 50 in the end wall 32. This guide rail 49 ensures that the scraper comb 47 cannot be rotated out of its horizontal position. This also ensures that the two fork-shaped recesses 44 are always at the same height, as a result of which the actuating rods 37 engaging in the fork-shaped recesses 44 are always arranged at the same height. This means that by guiding the scraper comb 47 by means of the guide rails 49 and the grooves 50, the two pivot elements 35 are synchronized. In the area below the recesses 44, L-shaped brackets 51 are attached to the end wall 32 pointing upward, the scraper comb 47 with its recess 44 being guided in the area between the L-shaped brackets 51 and the end wall 32. The upward-facing end faces of the L-shaped brackets 51 each form a support 52, the function of which is explained in more detail below.

A plate 53 with eight passages 54 is fastened to the outside of the second end wall 33. The passages 54 are at the same distance as the pipette tenadapter 19 of the pipetting head 1 is formed. A light barrier is provided below each of the passages 54, with which it can be checked whether a pipette tip 22 is attached to a pipette adapter 19.

The mode of operation of the device according to the invention is explained below.

In order to receive pipette tips 22, the pipetting head 1 is lowered above the actuating device 29 in such a way that the pipette adapters 19 are inserted into pipette tips located in the receiving area 34. Here, the pivot elements 35 are in their position pivoted against the vertical stop 39, which is referred to below as the open position.

Since the pipette tips 22 are individually spring-mounted by means of the helical springs 25, they can compensate for tolerances of the pipette tips 22 or deviations in the arrangement of the pipette tips 22 in the receiving area 34. The helical springs 25 surrounding the pipette adapters are made harder than the helical springs 28 between the connecting part 2 and the pipette part 3. As a result, the pipette part 3 is first inserted into the groove 4 of the connecting part 2 against the action of the helical springs 28. Only after the coil springs 28 have been compressed by a predetermined distance can the individual pipette adapters 19 be moved upward in the guide bores 16, 17.

The force exerted by the springs 28 on the individual pipette adapters 19 by inserting the pipetting head 1 by means of the robot arm into the actuating device is too low that the pipette adapters 19 are securely inserted into the pipette tips 22 for the further pipetting processes. These forces are so low that the robot arm is not subjected to excessive loads. Excessive stress on the robot arm would lead to inaccuracies in its movements.

The pipetting head 1 introduced into the actuating device 29 in this way is located with its engaging elements 15 approximately at the height between the bearing rod 36 and the actuating rod 37. The pivoting of the pivoting elements 35 presses the actuating rod 37 against the engaging elements 15. This will Pipette part 3 with pipette adapters 19 pressed down into pipette tips 22. Here, the springs 25 are compressed, whereby tolerances and deviations in the arrangement of the pipette tips 22 are compensated for. This contact pressure is so great that the pipette adapters 19 are sufficiently firmly inserted in the pipette tips 22. During this swiveling movement, the swiveling elements 35 generally do not strike the horizontal stops 40, but the current detection determines when a certain force is exerted and the further power supply is then switched off. This ensures that the pipette adapters 19 are pressed into the pipette tips 22 with a predetermined force.

In this pressing process exerted by the actuating device 29, the connecting part 2 is not moved. Only the pipette part 3 is moved in the area of the movement play explained above. As a result, the pressing process is mechanically decoupled from the robot arm. The range of motion is greater than the distance that the pipette adapter 19 needs to penetrate into the pipette tips 22.

After the pipette adapters 19 are firmly inserted into the pipette tips, the pivoting elements 35 are pivoted back into their open position and the pipetting head 1 is lifted off the actuating device with the robot arm.

To check whether a pipette tip 22 has been placed on all pipette adapters 19, the pipette head 1 with the pipette adapters 19 is lowered through the openings 54 in the plate 53. If no pipette tip 22 is attached to a pipette adapter 19, this is detected by one of the light barriers. If, on the other hand, it is found that 19 pipette tips 22 are seated on all pipette adapters, the pipetting head is released for pipetting.

If the absence of one or more pipette tips is detected by means of the light barriers, the attached pipette tips 22 are withdrawn by means of the stripping device 30 (explained in more detail below) and the pipetting head 1 with its pipette adapters 19 is inserted into a further row of pipette tips 22 of the receiving device 34, to record this. The pipetting head according to the invention is intended for use with disposable pipette tips. These pipette tips 22 must be removed from the pipette adapters 19 after each use.

For this purpose, the stripping device 30 with the stripping comb 47 is used. If the stripping comb 47 is in its upper position, which is the case with the pivot elements 35 in the open position (FIGS. 4, 5), the pipetting head 1 is attached to the stripping comb 47 with a horizontal movement such that the engaging elements 15 of the pipetting head 1 lie on the supports 52 and that in each case a pair of scraper teeth 48 encompass a pipette adapter 19 above the pipette tips 22.

The scraper comb 47 is pushed downward by pivoting the swivel elements 35, the scraper teeth 48 pulling off the pipette tips 22 from the pipette adapters 19. Due to the engagement of the engagement elements 15 or the lower strut 14 on the supports 52, the pipette adapters 19 anchored with their ring webs 21 in the countersunk bores 18 are fixed in position so that the pipette tips can be removed. This also ensures that no forces are transferred to the robot arm by pulling off the pipette tips 22. Thus, when the pipette tips 22 are stripped off, the pipetting head 1 is mechanically decoupled from the robot arm.

Afterwards, new pipette tips can be used to carry out a new pipetting process.

The invention has been described above using an exemplary embodiment. However, the invention is not limited to the specific embodiment. In the context of the invention, for example, the pipetting head can be designed with 16 or 32 pipette adapters. It is essential for the invention that the movement of the robot arm is mechanically decoupled from the pressing of the pipette adapter into the pipette tips, so that the robot arm is not subjected to excessive loads. LIST OF REFERENCE NUMBERS

pipetting

connecting part

pipette part

groove

drilling

connecting part

threaded holes

drilling

countersink

countersink

Beam free end upper strut lower strut

projections

guide bore

guide bore

countersink

pipette adapter

Through Hole

ring land

pipette tips

Groove tubular approach

coil spring

Blind holes

screw

coil springs

actuator stripping

baseplate

end wall

end wall

recording device

pivoting element

bearing rod

actuating rod

Swing lever vertical stop horizontal stop

gear

toothed belt

electric motor

recess

camp

recess

Abstreifkamm

Abstreifzacken

guide rail

roller bearing

groove

L-shaped bracket

In stock

plate

passage

Claims

claims 1. pipetting head for a robot which is provided with a plurality of pipette tips (22), which has a connecting part (2) which can be rigidly attached to a robot arm, and which has a pipette part (3) to which a plurality of pipette tips (22) can be attached characterized in that the pipette part (3) and the connecting part (2) are coupled to one another in such a way that they can move freely so that the pipette part (3) can be actuated in the region of the play by means of a separate actuating device (29). 2. Pipetting head according to claim 1, characterized in that the pipetting head (1) is provided with a plurality of pipette adapters (19) for receiving pipette tips (22). 3. Pipetting head according to claim 1 or 2; characterized in that the pipette adapters (19) are individually spring-mounted. 4. Pipetting head according to one of claims 1 to 3, characterized in that the pipette part (3) has engaging elements (15) on which the actuating device (29) for actuating the pipette part (3) can act. 5. Pipetting head according to one of claims 1 to 4, characterized in that the pipette part (3) is designed as a rectangular frame which consists of an inverted U-shaped carrier (11) and two between the free ends of the U-shaped carrier ( 11) extending struts (13, 14), which run parallel to one another, one of the two struts (14) being arranged a bit below the other strut (13) and the struts (13, 14) each having a plurality of guide bores (16 , 17) are provided. 6. Pipetting head according to claim 5, characterized in that the guide bores (17) of the lower strut (14) are each penetrated by a pipette adapter (19) having a collar (21) with a larger diameter than the guide bore (17) of the lower strut has, so that it is secured against falling out. 7. Pipetting head according to claim 6 or 7, characterized in that the lower strut (14) projects on both sides at the free ends (12) of the U-shaped carrier (11) to form the engaging elements. 8. Pipetting device with a pipetting head according to one of claims 1-7, characterized in that the device is provided with an actuating device (29) which is independent of the robot arm and which has a pressure mechanism which is attached to the engagement elements (15) of the pipetting head (1). to press the pipette adapter (19) into the pipette tips (22). 9. The pipetting device according to claim 8, characterized in that the pressure mechanism has two pivoting elements (35) which can be moved between a position in which the pipetting head (1) between the two pivoting elements (35) and a position in which the pivot elements (35) engage on the engagement elements (15), can be pivoted back and forth. 10. The pipetting device according to claim 9, characterized in that the pivoting elements (35) are elongate bodies which are arranged parallel to one another and are each designed to be pivotable about a pivot axis running parallel to the respective longitudinal extent. 11. Pipetting device according to claim 9 or 10, characterized in that the pivoting elements (35) are each controlled by an electric motor (43), the pivoting elements (35) being pivotable in each case between two end positions which are fixed by stops (39, 40) are, the end positions are detected by a current detection. 12. Pipetting device according to claim 11, characterized in that the pivoting elements (35) are mechanically synchronized. 13. Pipetting device with a pipetting head according to one of claims 1-7 and a stripping device for stripping pipette tips from the pipetting head, characterized in that the stripping device has two supports (52) for resting the pipetting head (1), the supports (52) are arranged in such a way that the pipetting head (1) with its pipette adapters (19) can be arranged in the area between the two supports, the scraper device has a scraper comb (47) which is arranged in the area between the supports (52) in this way and with scraper teeth (48 ) is designed such that a pipetting head (1) resting on the supports (52) can be arranged with the pipette adapters (19) between the stripping teeth (48), the distance between two adjacent stripping teeth (48) being less than is the maximum diameter of the pipette tips (22), and the stripping comb (47) can be moved along the pipette adapters (19) by means of a drive device for stripping the pipette tips (22). 14. Pipetting device according to claim 13 and one of claims 8 - 12, characterized in that the stripping device is designed combined with the actuating device, wherein the stripping comb (47) is coupled to the pivoting elements (35) of the actuating device (29), so that by the pivoting of the pivoting elements (35) of the scraper comb (47) is moved. 15. The pipetting device according to claim 14, characterized in that the stripping comb (47) is guided by means of a guide rail (49), so that the guided movement of the stripping comb (47) also guides the pivoting elements (35) coupled to it and thus synchronizes them.