EP3666379A1 - Pipetting head, pipette device comprising a pipetting head and method for pipetting by means of a pipetting head - Google Patents

Abstract

A pipetting head for a pipetting device comprising: - a carrier, - at least one extension held on the carrier for clamping pipette tips and - two O-rings made of an elastomer, - the two O-rings and the extension being formed, one Clamp the pipette tip on the attachment simply by deforming the two O-rings.

Description

The invention relates to a pipetting head for receiving pipette tips, to a pipetting device comprising a pipetting head and to a method for pipetting liquids by means of a pipetting head.

Pipetting devices with a pipetting head for holding a single or for simultaneously holding a plurality of pipette tips are used in particular in medical, biological, biochemical and chemical laboratories for metering liquids.

Pipetting heads have at least one attachment that can be inserted into a push-on opening at the top of a pipette tip. Through a tip opening at the lower end of the pipette tip, liquid is absorbed into and released from the pipette tip.

After use, the pipette tip can be detached from the attachment and exchanged for a fresh pipette tip. This avoids contamination during subsequent dosing. Plastic pipette tips for single use are available at low cost.

In the embodiment as an air cushion pipetting device, at least one displacement device for air is integrated into the pipetting device and communicatingly connected to a pipette tip clamped thereon in a communicating manner in each attachment. An air cushion can be displaced by means of the displacement device, so that liquid is sucked into the pipette tip and ejected therefrom. The displacement device is usually a cylinder with a piston which is displaceable therein. However, displacement devices are also known with a displacement chamber and at least one deformable wall, wherein a deformation of the wall causes the displacement of the air cushion.

In the design as a direct displacement pipetting device, a small piston is arranged in the pipette tip, which is coupled to a piston drive of the pipetting device when the pipette tip is plugged onto the shoulder.

The liquid is preferably taken up in a single step or in several small steps. The liquid is dispensed in a single step when pipetting and in several small steps when dispensing.

The pipetting devices can be designed as manually or electromotively driven, manageable multi-channel pipettes which are held in the hand by the user during pipetting (“hand pipettes”).

In the case of metering stations (“pipetting stations”) or automatic metering devices (“pipetting machines”), the pipetting head can be displaced on a robot arm or another transmission system for moving the pipetting head above a work surface. Dosing stations or automatic dosing devices can use the pipetting head to take up fresh pipette tips from a holder, take up liquids from vessels with the pipette tips and dispense them into vessels and throw used pipette tips into a waste container. Pipetting heads can be part of laboratory machines ("workstations"), which can perform other liquid treatments in addition to the dosing of liquids. This includes in particular mixing, tempering and other physical treatments, chemical or biochemical conversion and the analysis of samples.

The approaches for holding pipette tips are often designed as a conical, cylindrical or partly conical and partly cylindrical projection with respect to a housing or another carrier of the pipetting device. Pipette tips can be clamped onto a shoulder with a sealing seat next to a push-on opening at their upper end. For this purpose, at least one attachment is pressed into the plug-in opening of at least one pipette tip which is provided in a holder, so that the pipette tip widens somewhat and is stuck on the attachment under pretension. The force to be applied for the clamping increases with the number of pipette tips.

In order to release the clamped pipette tip from the attachment, the pipetting devices have a discharge device with a drive device and a discharge device. By actuating the drive device, the ejector is displaced in such a way that it detaches the pipette tip from the attachment. The drive device is driven either manually or by an electric motor. The ejection force for releasing pinched pipette tips from the base increases with the number of pipette tips.

High forces must be applied to clamp pipette tips onto 8, 12, 16, 24, 96 or 384 tips and to drop the pipette tips from the tips.

The DE 10 2004 003 433 B4 describes a multi-channel pipette in which the force required to clamp the pipette tips on the tips and to detach the pipette tips from the tips is reduced in that the tips are spring-loaded and project in the axial direction beyond a stop formed by the ejector. If the clamping force exceeds a certain value when clamping pipette tips, the tips deflect until the pipette tips are in contact with the ejector. This limits the clamping force to a value in which the pipette tips are held sealingly on the approaches. Accordingly, the ejection force is limited.

The EP 2 735 369 A1 describes a multi-channel pipette in which the ejector serves as a stop element when pushing the pipette tips onto the tips. The ejection forces are further reduced in that the ejector has a plurality of contact elements which meet the pipette tips one after the other in order to push them off the attachments.

The WO 01/56695 A1 describes a pipetting head with 96 channels, the lugs at the lower end have a larger cone angle than above, in order to reduce the force for attaching pipette tips with a collar of greater wall thickness at the upper end and a smaller wall thickness below the collar. The pipetting head comprises a stop plate for ejecting the pipette tips from the attachments. The stop plate is stepped to successively push the pipette tips away from the tips and to reduce the ejection force. Posts with pretensioning devices protrude from the stop plate. A plunger plate, which displaces pistons in cylinders connected to the lugs, strikes the pretensioners when retracted to trigger dropping of the pipette tips from the lugs through the stop plate. The construction with pretensioners for ejecting pipette tips is complex.

The WO 2005/113149 A1 describes a device for receiving and dispensing liquids with a pipetting head, which has 96 approaches for pipette tips. 96 piston-cylinder units are connected to the lugs and can be operated manually using a drive mechanism. The pipetting head can be displaced along a vertical guide, around pipette tips from a pipette tip holder absorb and aspirate and dispense liquid. The pipetting head can be pressed down by means of a transmission lever with increased force in order to apply the force required to hold 96 pipette tips. The lugs are passed through holes in a perforated plate which can be displaced vertically in order to strip the pipette tips from the lugs.

The DE 20 2008 013 533 U1 describes a pipetting device with a base plate and an elastic sealing plate that laterally covers the outside thereof, wherein a multiplicity of pipetting channels arranged in a predetermined grid are passed through the base plate and the sealing plate. A magazine equipped in the same grid with pipette tips, each of which has a collar, is connected to the base plate in a lying manner in a magazine holder indirectly via the collars and the sealing plate. The magazine holder is formed by a magazine frame which can be raised and lowered by a drive motor via an eccentric gear in order to bring the pipette tips into sealing contact with the sealing plate or to detach them from the sealing plate.

Automatic pipetting devices, in which pipette tips are received in a magazine in a magazine holder and pressed onto a sealing plate, are marketed by the company Apricot Designs, Inc., Covina, CA, USA, under the product names "i-Pipette" and "i-Pipette Pro" .

It is disadvantageous that these automatic pipetting machines can only work together with special pipette tips in a special magazine. A further disadvantage is that the magazine holder is loaded by hand.

The EP 0 337 726 A2 describes a device for simultaneously picking up several pipette tips by means of parallel approaches in a straight row, each have an elastomeric O-ring in an annular groove with an adjustable groove width. The extent of the O-rings in the circumferential direction can be changed by adjusting the groove widths in order to tightly clamp the pipette tips onto the attachments and to detach the pipette tips from the attachments. To adjust the groove widths, the grooves are each limited by a threaded sleeve screwed onto the shoulder, which can be rotated on the shoulder by means of a coupled gear mechanism. Each threaded sleeve is firmly connected to a gear. The gears mesh with a single rack that is driven by a rotating handle. In an alternative embodiment, each individual threaded sleeve is individually driven by an electric motor and the electric motors are connected to a common voltage supply for synchronous operation. The drive for clamping the pipette tips on the approaches is structurally complex.

The DE 199 17 375 C2 describes a pipetting unit with a pipette tip and an attachment, which has a pipetting tube with a coupling sleeve at the lower end, an O-ring made of elastically deformable material which is pushed onto the pipetting tube, and a sleeve which is pushed onto the pipetting tube. The sleeve serves to axially pinch the O-ring, so that it deforms radially and engages in a sealing manner in an annular groove on the inner circumference of the pipette tip. The O-ring can be relieved to release the pipette tip. In order to hold the pipette tip on the attachment in a predetermined position, the attachment and the pipette tip have cooperating axial positioning means. The fact that the O-ring engages in an annular groove of the pipette tip prestresses the axial positioning means which are in contact with one another. A movable ejector is provided to eject the pipette tip and is designed as an ejector tube enclosing the sleeve. The ejector can be actuated hydraulically or by an electric motor or by means of a pretensioning spring which is tensioned when the pipette tip is placed on the pipetting unit becomes. The actuating means for clamping and releasing the pipette tip at the base are complex and take up a lot of space. The attachment of the pipette tips in the defined coupling position can easily be prevented by manufacturing tolerances or an inaccurate positioning of the pipette tip on the attachment. The annular groove and the axial positioning means restrict the use of different pipette tips.

The WO 2018/002254 A1 describes a dosing head for a dosing device with a carrier, on which a plurality of parallel approaches for receiving pipette tips is arranged side by side. Each approach has a tube with an at least partially circumferential support projection projecting outward at the lower end from the outer circumference, at least one sleeve which surrounds the tube and is axially displaceable on the tube, and at least one elastomeric O-ring which surrounds the tube and is located next to the lower end of the sleeve. Above the sleeves there is a pressure plate with a plurality of first holes through which the tubes extend, the pressure plate along the tubes between a release position at a first distance from the support projections and a clamping position at a second distance below the first distance the support projections is displaceable, the pressure plate in the clamped position presses against the upper edge of the adjacent sleeves of all the lugs so that the sleeves are pressed with the lower ends onto the adjacent O-rings and the O-rings are widened to expose pipette tips pushed onto the lugs to clamp. A first displacement device is connected to the pressure plate and is designed to shift the pressure plate between the release position and the clamping position.

Simultaneous clamping and loosening of a large number of pipette tips is achieved by evenly pressing the pressure plate against all sleeves and through enables even relieving of all sleeves. The transmission of force from the first adjustment device via the pressure plate to the sleeves favors a relatively simple, compact and lightweight construction. Clamping by widening the O-rings favors the use of pipette tips with different shapes and dimensions.

The DE 10 2006 036 764 writes a pipetting system with a pipetting device with at least one push-on shaft, which has a circumferential locking bead on the outer circumference and underneath it two circumferential annular grooves which are spaced apart from one another and each accommodate a sealing ring. The pipetting system comprises a pipette tip which can be clamped onto the latching bead with a latching groove and has a sealing area beneath it, against which the sealing rings bear in a sealing manner. Due to the latching, a defined fit of the pipette tip on the plug-on shaft is achieved and the sealing rings seal the pipette tip against the plug-on shaft. Relatively high attachment forces are required to lock the locking bead and locking groove.

Proceeding from this, the object of the invention is to provide a pipetting head with at least one approach for receiving at least one pipette tip, which enables a safe picking up and loosening of pipette tips with reduced effort and reduced construction effort.

The object is achieved by a pipetting head with the features of claim 1. Advantageous embodiments of the invention are specified in the subclaims.

• einen Träger,
• mindestens einen an dem Träger gehaltenen Ansatz zum Aufklemmen von Pipettenspitzen, und
• zwei auf dem Ansatz gehaltene O-Ringe aus einem Elastomer,
• wobei die beiden O-Ringe und der Ansatz ausgebildet sind, eine Pipettenspitze allein durch Verformung der beiden O-Ringe auf dem Ansatz festzuklemmen.

The pipetting head according to the invention for a pipetting device comprises:

• a carrier,
• at least one approach held on the carrier for clamping pipette tips, and
• two elastomer O-rings held on the base,
• the two O-rings and the attachment being designed to clamp a pipette tip on the attachment solely by deforming the two O-rings.

Pipette tips are elongated tubes which have a tip opening at their lower end and a sealing seat at their upper end next to a push-on opening, with which they can be clamped onto the attachment. The inside diameter and outside diameter of the pipette tips generally increases from the tip opening to the push-on opening. If a pipette tip is picked up on a neck of a pipetting head that has no O-ring, only one O-ring or a locking bead and two O-rings, high absorption forces arise (push-on forces, clamping forces) because the pipette tip, which is made of polypropylene, polyethylene or another hard elastic plastic, comes into direct contact with the attachment when pushed onto the attachment and deforms in the process. The fact that the two O-rings and the neck are designed in the pipetting head according to the invention in such a way that a pipette tip can be clamped onto the neck solely by deformation of the two O-rings, direct contact of the pipette tip with the neck can be avoided and occurs in If the pipette tips are picked up by the pipetting head, a deformation takes place only on the two O-rings. The inner diameter of the sealing seat of the pipette tip is smaller than the outer diameter of the respective O-ring at the point that contacts an O-ring, so that it is deformed when pushed on and the pipette tip clamps on the shoulder. Since the O-rings are made of an elastomer, they can be deformed more easily than that Pipette tip. This reduces the absorption force required to hold the pipette tips. By reducing the clamping forces on a hand-held pipette, the load on the user during manual pipetting can be reduced. In the case of a pipetting station, an automatic pipetting machine or a laboratory machine, this reduces the requirements for the transmission system, in particular for its strength and the performance of the drives.

In addition, the two O-rings ensure that the pipette tips are precisely aligned with the attachment. This is advantageous for the insertion of pipette tips into the openings of vessels without colliding with the vessels. In this way, in particular a tilting of the pipette tip can be avoided if it contacts the wall of the vessel with the lower end during hand pipetting. This is recommended by the pipette manufacturers so that the liquid flows out of the tip opening under uniform conditions.

Another advantage of the two O-rings on each attachment is that all tips can be pushed onto the attachment in such a way that they can subsequently be pushed up further on the attachment and later pushed up into a position for pipetting. Alternatively, all tips can be pushed up to the ejector or stop on the attachment, so that the clamped pipette tips always have the same height.

According to a preferred embodiment, the pipette tips can be tightly clamped onto the attachment, so that the pipetting head can be used to absorb and dispense liquid by means of at least one clamped-on pipette tip. For this purpose, the pipetting head has at least one displacement device which communicates with one via at least one line Connection hole is connected at the end of the approach to displace an air cushion and to receive liquid through the tip opening in a clamped pipette tip and to dispense from it. Due to the radial deformability of the two O-rings, it is possible to hold pipette tips with different dimensions on the same attachment and to pipette with the different sized pipette tips. As a result, the effort for performing various pipetting tasks can be reduced. For example, the O-rings and the attachment can be designed such that pipette tips with a nominal volume of 10 µl and 50 µl or with a nominal volume of 300 µl and 1,000 µl can be clamped on the same attachment. Commercial pipette tips from different manufacturers can be used for this, since these have matching dimensions in the sealing area.

If the dimensions of the different pipette tips differ more, the pipetting head can, if necessary, be used to transfer pipette tips of different sizes, e.g. from one pipette tip holder to another pipette tip holder, since the pipette tips are not tightly clamped on the tips, but so firmly on the tips Approaches sit that they are transferable by means of the pipetting head. This can be used in particular for the automatic transfer of pipette tips in a laboratory machine. For example, the O-rings and the attachment can be designed in such a way that commercially available pipette tips with a nominal volume of 10, 50, 300 and 1,000 µl can be picked up and transferred using the same attachment. The invention includes pipetting heads that can be used for the transfer of pipette tips, but not for the absorption and dispensing of liquids. Such a pipetting head for transferring pipette tips can without Displacement device are formed and is also referred to below as a transfer head.

According to a further embodiment, the O-rings are made from a soft elastomer. According to a further embodiment, the O-rings are made of rubber, silicone rubber, fluororubber (FEPM - for example Viton® from DuPont Performance Elastomers), hydrogenated nitrile rubber (HNBR), ethylene-propylene-diene rubber (EPDM) or a thermoplastic Made of elastomer. O-rings made of a soft elastomer (silicone rubber) are marketed in particular by C. Otto Gerckens GmbH & Co. KG Dichtungstechnik, Pinneberg, Germany under the name VMQ.

According to a further embodiment, the attachment has devices for the axial securing of position, which are designed to support each of the two O-rings in a certain upper and in a certain lower position and to allow deformation of the two O-rings in the radial direction. As a result, the two O-rings can be held on the shoulder in defined positions or areas. These can be matched to the pipette tips that are to be held on the attachment.

According to a further embodiment, the devices for securing the axial position are annular grooves. Each ring groove can partially accommodate at least one O-ring, the O-ring being guided on the base of the ring groove on the shoulder and prevented by the two flanks of the ring groove from being displaced upwards and downwards. The ring grooves can be dimensioned such that each O-ring is held in the respective ring groove with a precise fit, or with an axial play or in a slightly compressed manner in the axial direction. It is also possible to keep both O-rings in the same ring groove. Here both O-rings are supported in same annular groove from each other and the upper O-ring is supported on the upper flank and the lower O-ring on the lower flank of the annular groove.

According to another embodiment, the devices for the axial securing of position are formed by one or more projections which are arranged on both sides of at least one O-ring on the circumference of the extension. A displacement in the axial direction is prevented or limited by the at least one projection on both sides of at least one O-ring.

According to a preferred embodiment, each approach has only two O-rings. According to another embodiment, each approach has more than two O-rings. For each O-ring there can be a separate ring groove or other devices for axial securing of the position or several O-rings can be arranged together in the same ring groove or held on the shoulder by the same devices for axial securing of the position.

According to a further embodiment, the devices for the axial securing of position are formed in one piece with the attachment. According to another embodiment, the devices for axially securing the position are sleeves and / or rings which are pushed onto the neck and receive the O-rings between them, which are guided on the inside of the neck. The sleeves and / or rings are either fixed on the neck or loosely guided on the neck and prevented from being stripped from the neck by additional means for securing the position axially. These can be formed, for example, at the top by the carrier and at the bottom by a securing ring which is held in an additional annular groove on the circumference of the attachment.

According to a further embodiment, the two O-rings are arranged on the shoulder at a distance from one another. This is particularly advantageous for the precise alignment of the pipette tips on the approach. This also enables a particularly gentle increase in the clamping forces when clamping a pipette tip.

According to a further embodiment, the approach has at least one conical section. This is advantageous for clamping pipette tips onto the attachment with a gradual increase in the clamping forces.

According to a further embodiment, the extension has at least one cylindrical section. The guidance and sealing of a pipette tip at the base can be improved by the cylindrical section.

According to a further embodiment, the projection has an upper cylindrical section at the top, a lower cylindrical section at the bottom, a conical section tapering from top to bottom between them, and between the upper cylindrical section and the conical section, upper devices for securing the axial position and between the conical section and the lower cylindrical section lower devices for axial position securing. In this way, it can be achieved that the clamping forces gradually increase when the pipette tip is clamped onto the attachment and the pipette tip is well guided and aligned on the attachment.

According to a further embodiment, the upper O-ring has a larger inner diameter and / or a cross section with a larger diameter than the lower O-ring. This is advantageous for a gradual increase in the push-on forces when a pipette tip is clamped onto the attachment.

According to a further embodiment, the diameter of the cross section of the upper O-ring is larger than the depth of the upper ring groove and / or the width of the upper ring groove is equal to or larger than the diameter of the cross section of the upper O-ring and / or the diameter of the Cross section of the lower O-ring is greater than the height of the lower ring groove and / or the width of the lower ring groove is equal to or greater than the diameter of the cross section of the lower O-ring. The depth of the respective annular groove ensures that the respective O-ring can be deformed in the radial direction by clamping a pipette tip onto the attachment, and / or the length of the respective annular groove results in a long deformation path with low clamping forces.

According to a further embodiment, the pipetting head has approaches which are arranged next to one another in parallel in one or more rows. As a result, the pipetting head can be used for the simultaneous clamping of a large number of pipette tips, for which it is particularly well suited due to the low clamping forces.

According to a further embodiment, the approaches are firmly connected to the carrier. The clamping forces can be kept low by the two O-rings, so that it is in particular not necessary to support the attachments via springs on the carrier. According to another embodiment of the pipetting head according to the invention, the lugs are supported on the carrier via springs in order to thereby additionally limit the attachment forces.

According to a further embodiment, the carrier is a housing or part of a housing or a chassis or part of a chassis of the pipetting head. For example, the carrier is a lower housing wall of the housing or a lower part of a chassis of the pipetting head. The approach can be held in particular by screwing in a lower housing wall or in a lower part of a chassis. If the extension is held in a lower part of a chassis, the housing in a lower housing wall can have a through hole for each extension or the lower housing wall can be missing.

Furthermore, the invention relates to a pipetting device or a transfer device comprising a pipetting head according to one of claims 1 to 10 or one of the above embodiments. The pipetting device or transfer device can in particular be designed as a manually or electromotively driven, manageable pipetting device or transfer device with one or more channels, which can be held in the hand by the user when pipetting or transferring pipette tips (hand pipette).

Furthermore, the invention relates to a pipetting station or an automatic pipetting device or an automatic laboratory device comprising a pipetting device and / or a transfer device according to claim 11. The pipetting station or the automatic pipetting device or the automatic laboratory device can be used for (automatic) pipetting or transferring pipette tips. The laboratory machine can be used for automatic pipetting, for transferring pipette tips and also for other treatments of liquids, for example for tempering, mixing, carrying out chemical or biochemical reactions and other physical, chemical or biochemical treatments.

In a pipetting station, a pipetting machine or a laboratory machine, the pipetting head can be designed such that it can be attached to and detached from the pipetting station, the pipetting machine or the laboratory machine by means of a quick-change device in order to attach another one Attach pipetting head (e.g. for other pipette tip sizes ), a gripper tool for transporting laboratory items ( labware ) or another tool. This type of design is also referred to as a pipetting tool.

• auf jeden Ansatz des Pipettierkopfs eine Pipettenspitze aufgeklemmt wird,
• der Pipettierkopf verlagert wird, bis jede aufgeklemmte Pipettenspitze mit ihrem unteren Ende Kontakt mit einem Gefäß hat, das auf einer Arbeitsfläche bereitgestellt wird,
• der Pipettierkopf verlagert wird, bis das untere Ende jeder aufgeklemmten Pipettenspitze bis auf einen bestimmten Abstand von einem Boden des Gefäßes entfernt ist und
• Flüssigkeit aus dem Gefäß in jede aufgeklemmte Pipettenspitze aufgenommen wird.

Furthermore, the invention relates to the use of a pipetting head according to one of claims 1 to 10, a pipetting device according to claim 11 or a pipetting station or a pipetting machine or a laboratory machine according to claim 12, in which

• a pipette tip is clamped onto each attachment of the pipetting head,
• the pipetting head is shifted until each clamped pipette tip has with its lower end contact with a vessel which is provided on a work surface,
• the pipetting head is displaced until the lower end of each clamped pipette tip is at a certain distance from a bottom of the vessel and
• Liquid from the vessel is taken up in each clamped pipette tip.

For a variety of applications, it is desirable to take the liquid in a pipette tip in close proximity to the bottom of a vessel. These applications include, for example, efficient washing steps and the optimal recovery of liquids below phase limits. There are a number of tolerances in a pipetting station, an automatic pipetting machine or in a laboratory machine, which influence the final positioning of the tip opening in the vertical direction. In particular when using multi-channel pipetting heads, in particular in the version with a quick-change device (multi-channel pipetting tools), the exact positioning of the individual pipette tips is not possible.

The use of a pipetting head with two O-rings per approach makes it possible to allow unknown tolerance chains due to slight differences in the fit of the pipette tips with the same dosing quality. For this purpose, the pipette tips are first picked up by means of a pipetting head with only one or more channels, until pipette tips are clamped onto all the approaches. Here, the pipette tips are not pushed completely onto the attachments, ie not up to an ejector or a stop, so that they can be pushed even further up onto the attachments. The pipetting head is then moved and the lower ends of all clamped pipette tips are placed on the vessel from which liquid is to be removed or released into the liquid. Known and unknown tolerances are compensated for by placing the lower ends of the pipette tips on the tubes. Here, the pipette tips can be pushed a little further up onto the attachments, to a different extent, depending on whether they touch the vessels with their lower ends sooner or later. Then all clamped pipette tips are immersed in a vessel until they are a short distance from the bottom of the vessel. This creates a small gap for the absorption of liquids between the tip opening and the bottom of the vessel. The process can be carried out fully automatically, so that there is no additional effort for the user. The process can take place during a program run of a laboratory machine. The seat of the clamped pipette tips can be adapted to the individual receptacles (cavities) of the single or multiple receptacles used or other consumables ( disposables ).

According to one embodiment, the pipetting head is shifted until all clamped pipette tips with the lower ends simultaneously come into contact with the Have bottom of a vessel and then the pipetting head is moved until the lower ends of all pipette tips are a certain distance from the bottom of the vessel. As a result, a particularly small gap can be achieved between the lower ends of the pipette tips clamped in each case and the bottom of the vessels. According to another embodiment, the pipetting head is moved until the lower ends of all clamped pipette tips are in contact with a part of the surface of the vessel other than the bottom. In this way, at least an exact alignment of the pipette tips to the vessels is achieved, only tolerances between the position of the contacted surface and the bottom of the vessel not being compensated for.

According to a further embodiment, the pipetting head is a multi-channel pipetting head and the vessel is a multiple vessel, in particular a microtest plate (microtiter plate). The invention is particularly suitable for the simultaneous compensation of a large number of tolerances between clamped pipette tips and a micro test plate. Here, each pipette tip is first brought into contact with a surface of the multiple vessel or with the bottom of a well ( well ) or other cavity of the multiple vessel and then at a short distance from the bottom of the cavity.

If it is not possible to move the pipetting head so that each clamped pipette tip has its lower end in contact with a vessel that is provided on a work surface, for example because the vessel is filled with a liquid that is not in contact with the pipette tip the pipetting head can also be used in such a way that all pipette tips are pushed up to an ejector or stop on the shoulder, so that all clamped pipette tips have the same height. This reduces the errors due to tolerances, although not in the same extent as when moving the pipetting head so that the clamped pipette tips are in contact with the vessel at their lower end.

Fig. 1

einen Pipettierkopf mit aufgeklemmten Pipettenspitzen in der Vorderansicht;

Fig. 2

denselben Pipettierkopf ohne Pipettenspitzen in der Rückansicht;

Fig. 3

denselben Pipettierkopf mit aufgeklemmten Pipettenspitzen in einem Vertikalschnitt;

Fig. 4

einen Ansatz desselben Pipettierkopfs mit einer aufgeklemmten Pipettenspitze in einem vergrößerten vertikalen Teilschnitt;

Fig. 5

Aufsteckkräfte in Abhängigkeit vom Weg des Pipettierkopfes beim Aufklemmen auf einen herkömmlichen und auf einen erfindungsgemäßen Pipettierkopf in einem Diagramm;

Fig. 6

Toleranzketten und -Summen in einem Dosiersystem in einer grob schematischen Ansicht;

Fig. 7

Ansätze eines Mehrkanal-Pipettierkopfs mit aufgenommenen Pipettenspitzen oberhalb des Bodens einer Mikrotiterplatte in einer grob schematischen Ansicht;

Fig. 8

das Pipettierwerkzeug mit durch Aufsetzen auf den Bodenbereich der Mikrotiterplatte individuell eingestellten Pipettenspitzen in einer grob schematischen Ansicht;

Fig. 9

das Pipettierwerkzeug mit individuell eingestellten Pipettenspitzen zurückgezogen bis auf einen kleinen Abstand vom Bodenbereich der Mikrotiterplatte in einer grob schematischen Ansicht.

The invention is explained in more detail below with reference to the attached drawings of exemplary embodiments. The drawings show:

Fig. 1

a pipetting head with clamped pipette tips in the front view;

Fig. 2

the same pipetting head without pipette tips in the rear view;

Fig. 3

the same pipetting head with clamped pipette tips in a vertical section;

Fig. 4

an approach of the same pipetting head with a clamped pipette tip in an enlarged vertical partial section;

Fig. 5

Push-on forces depending on the path of the pipetting head when clamped onto a conventional pipetting head and onto a pipetting head according to the invention in a diagram;

Fig. 6

Tolerance chains and sums in a dosing system in a roughly schematic view;

Fig. 7

Approaches of a multi-channel pipetting head with picked up pipette tips above the bottom of a microtiter plate in a roughly schematic view;

Fig. 8

the pipetting tool with pipette tips individually adjusted by placing them on the bottom area of the microtiter plate in a roughly schematic view;

Fig. 9

the pipetting tool with individually adjusted pipette tips withdrawn to a small distance from the bottom area of the microtiter plate in a roughly schematic view.

In this application, the information “above” and “below”, “horizontally” and “vertically” relates to an alignment of the pipetting head with the lugs in the vertical direction, the lugs being arranged below and the remaining parts of the pipetting head above.

In the description of various embodiments, the same reference numerals are used for components with identical designations.

According to Fig. 1 and 2nd the pipetting head 1 has a housing 2 which is formed from a front and a rear housing shell 3, 4 which are joined together in a vertical plane.

From the underside of the pipetting head 1, eight parallel lugs 5 (pins) for clamping pipette tips 6 project vertically downwards ( Fig. 3 and 4th ).

A strip-shaped carrier plate 7 is arranged on the top of the housing 2. A mounting pin 8 projects upward from the carrier plate 7.

According to Fig. 3 eight parallel piston-cylinder units 9 are arranged in a row next to one another in the pipetting head 1. Each piston-cylinder unit 9 has a cylinder 10 in which a piston 11 is slidably arranged.

Each cylinder 10 has an external thread 12 with which it is screwed into a corresponding internal thread 13 in a through hole 14 in a horizontal lower housing wall 15. The screwing in of the cylinders 10 into the lower housing wall 15 is limited by shoulders 16 on the outer circumference of the cylinders 10, with which they rest on the upper side of the lower housing wall 15.

The lower part of the cylinders 10 projects outwards from the underside of the lower housing wall 15 and forms the lugs 5 there. Housing 2 is thus a carrier for the lugs 5.

According to Fig. 4 each projection 5 has an upper cylindrical section 17 at the top, a lower cylindrical section 18 at the bottom and a conical section 19 tapering from top to bottom therebetween. On each lug 5 are between the upper cylindrical section 17 and the conical section 19 upper devices for axial position securing 20 in the form of an upper annular groove 21 and between the conical section 19 and the lower cylindrical section 18 lower devices for axial position securing 22 in the form of a lower Ring groove 23 available.

An O-ring 24, 25 made of an elastomer, preferably made of a soft elastomer, in particular made of a soft silicone rubber, is inserted into each annular groove 21, 23. Each O-ring 24, 25 is guided at the bottom of the annular groove 21, 23 and has a cross section with a diameter which is greater than the depth of the annular groove 21, 23 and which is smaller than the width of the annular groove 21, 23 in which he is arranged.

The interior 26 of each cylinder 10, into which the piston 11 dips from above, extends down to a connecting hole 27 in the lower end face of the extension 5.

At the top of each cylinder 10 there is a bushing 28, through which a piston 11 is sealingly inserted into the cylinder 10.

Each piston 11 is designed as a cylindrical rod which is inserted at the top into a central bore 29 of a cylindrical piston head 30 and fastened therein (e.g. glued or pressed in). Each piston head 30 has a circumferential annular ring groove 31 on the outer circumference.

A strip-shaped piston plate 33 parallel to this is arranged below a horizontal upper housing wall 32. The piston plate 33 has eight downwardly open channels 34, which are aligned parallel to one another. Each channel is delimited by two strip-shaped channel walls 35 and by two channel shoulders 36 projecting inwards from the lower ends of the channel walls. The channel walls 35 on the two outer edges of the piston plate 33 each delimit an adjacent channel 34 on only one side. The remaining channel walls 35 each delimit two adjacent channels 34 on one side. Between the channel shoulders 36, each channel has a slot opening 37 on the underside of the piston plate 33.

At the edges of the piston plate 33, which are aligned parallel to the front and rear of the housing 2, the channels 34 have end openings 38. Through the end openings 38, the piston heads 30 are inserted with upper sections into the channels 34, so that the channel shoulders 36 form-fit engage the piston head ring grooves 31. As a result, the pistons 11 can be moved together in the cylinders by vertically displacing the piston plate 33.

An axially displaceable threaded nut 39 is arranged centrally in the fastening pin 8, the lower end of which is firmly connected to the piston plate 33 in order to displace the piston plate 33 in the axial direction of the cylinder 10.

The fastening pin 8 has a cylindrical upper pin section 40 at the top. The upper pin section 40 carries on the outer circumference two connecting elements 41 which are offset by 180 ° and project radially outwards, in each case partially circumferentially, with which a bayonet connection can be formed. The connecting elements 41 have a slight thread pitch on the underside for bracing with a matching connecting element in a pin receptacle of a bayonet connection.

Adjacent to the upper pin section 40, the fastening section 8 has a cylindrical central pin section 42 with a larger outer diameter than the upper pin section 40.

Underneath, the fastening pin 8 has a lower pin section 43 that widens conically downward. The lower pin section 43 is firmly connected at its base to the carrier plate 7.

A central bore 44 extends in the longitudinal direction of the fastening pin 8. This has two diametrically opposed longitudinal grooves 45.

In the central bore 44, the sleeve-shaped threaded nut 39 is inserted, which is guided with two radially projecting wings 46 at its upper end in the longitudinal grooves 45.

Furthermore, a spindle 47 is screwed into the threaded nut 39. This has a protruding bearing pin 49 above its thread 48, on which it is mounted in a ball bearing 50. The ball bearing 50 is held in a bearing bush 51 of a bearing bracket 52 which protrudes two diametrically from the sides Has tabs that rest on the upper edge of the upper pin section 40 and are fixed there by means of screws.

On the part of the bearing pin 49 projecting beyond the ball bearing 50, a driver 54 is fixed in a rotationally fixed manner by means of a radial threaded pin 53 and has a radially and axially extending slot 55 on its upper end face for inserting a pawl-shaped drive element.

The spindle 47 is supported on the lower end face of the ball bearing 50. The driver 54 is supported on the upper end face of the ball bearing 50. As a result, the spindle 47 is not axially displaceably held in the fastening pin 8.

In a wing 46 of the threaded nut 39, a cylindrical pin 56 is fixed, which, parallel to the central axis of the threaded nut 39, is guided through a groove of the bearing bracket 52 and protrudes from the fastening pin 8 at the top.

By turning the driver 54, the spindle 47, which is held axially in the fastening pin 8, moves the threaded nut 39, which is non-rotatably guided in the fastening pin 8, in the axial direction. As a result, the piston plate 33 is displaced and the pistons 11 are displaced in the cylinders 10. By rotating the driver 54 in different directions, the pistons 11 can be displaced in the cylinders 10 in different directions. By scanning the position of the cylinder pin 56, it is possible to determine the respective position of the pistons 11 in the cylinders 10.

The fastening pin 8 and the drive integrated therein with a threaded nut 39 and a spindle 47 correspond to the designs from 1 to 4 and 6 according to EP 1 407 861 B1 . In this regard, reference is made to the EP 1 407 861 B1 , the content of which is hereby incorporated into this application.

A laboratory machine is provided with a complementary pin receptacle of a bayonet connection, which can be connected to the fastening pin. The complementary connecting part of the laboratory machine preferably corresponds to the tool holder 7 to 10 the EP 1 407 861 B1 . In this regard, reference is made to the EP 1 407 861 B1 , the content of which is hereby incorporated into this application.

A stripper plate 57 is arranged below the lower housing wall 15 and has further through holes 58 through which the pins 5 project downwards. The stripping plate 57 is connected on one long side to a linkage 59 which is guided upwards in a bulge 60 of the rear housing shell 4, which has an opening at the top through which the linkage 59 protrudes from the housing 2. A driver 61 projects laterally from the upper end of the linkage 59. In the idle state, the linkage 59 is pressed upwards by means of a spring device, not shown, until the stripping plate 57 rests on the underside of the lower housing wall 15. The automatic laboratory machine has a drive with a drive element with which the driver 61 can be pressed down, as a result of which the stripping plate 57 is carried downwards in order to strip pipette tips 6 from the projections 5.

According to Fig. 3 and 4th are pipette tips 6 clamped on the approaches 5. The pipette tips 6 are tubes with a tip opening 62 at the lower end 63 and a push-on opening 64 at the upper end 65. The inner diameter and the outer diameter of the pipette tip 6 generally increase from the tip opening 62 to the push-on opening 64. In the example they have Pipette tips 6 have a plurality of conical regions 64, 65, 66 and a cylindrical extension 67 in the vicinity of the upper end 65. In the region of the cylindrical extension 67 and in the region below, the pipette tip has a sealing seat 68 on the inside.

According to Fig. 3 and 4th the shoulders 5 of the pipetting head 1 are inserted into the pipette tips 6 through the plug-on openings 64. The O-rings 24, 25 are arranged at the level of the sealing seat 68. As a result, the O-rings 24, 25 are compressed somewhat in the radial direction, so that the pipette tips 6 clamp on the shoulders 5 and are sealed off from the shoulders 5. Since the O-rings 24, 25 consist of soft elastic material and the pipette tips 6 are otherwise not in contact with the projections 5, the push-on forces for attaching the pipette tips 6 to the projections 5 are relatively small.

In Fig. 5 are the measured attachment forces when attaching pipette tips as a function of the path of the pipetting head for an inventive pipetting head 1 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 Approaches shown side by side. According to the three curves on the left in the diagram, when using a conventional pipetting head, the push-on forces increase sharply until they are seated on the attachments with sufficient firmness and sealing. This is the case with an attachment force of 120 Newtons and a displacement of the pipetting head of 2.2 mm. According to the curves on the right in the diagram, an adequately firm and sealing connection is established even with attachment forces of approx. 30 Newton and a displacement of the pipetting head of 2 mm. Here, only the O-rings 24, 25 are elastically deformed. Above this value, the push-on forces rise steeply, since this also requires the pipette tips 6 to be deformed.

The reduced plug-on forces also reduce the forces for throwing off the pipette tips 6 from the projections 5.

The following is based on the 6 to 9 the use of the invention explained. According to Fig. 6 an automatic laboratory machine 70 has a large number 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 transmitter 71 (robot arm or other transmission system). In addition, there are the tolerances of the fixation of a pipetting head 1 (pipetting tool) in the tool holder 72 held on the multi-axis transmitter 71. Furthermore, manufacturing tolerances of the pipetting head 1 must be taken into account. In addition, the approaches 5 for receiving 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 automat 70 have further tolerances. Finally, the work surface 75 itself also has tolerances.

In particular when using multi-channel pipetting heads 1, the exact positioning of the individual pipette tips 6 is not possible, since the same height must be used for all pipette tips 6.

For many target applications, such as next-generation sequencing (NGS), this leads to quality losses due to reduced efficiency of the washing steps and / or reduced yields of sample material. In the worst case, contaminations are carried over, for example if a sample is to be aspirated under another phase (e.g. oil-covered samples) and parts of the overlay are carried over.

The reduction in tolerance ranges leads to lower process reliability and thus to an increased risk of sample loss. In addition, it only partially solves the problem, since certain tolerance ranges are not to be undercut. Often the immediate need for a very precise adjustment of the device increases in order to minimize individual tolerances.

The "surface teaching" addresses certain tolerances on the system (e.g. positioning offset and tool tolerance), but is very labor intensive for the user and requires a lot of effort. Furthermore, a large number of tolerances are not covered by surface teaching (e.g. well (well) geometry, microtiter plate seat on adapter, pipette tip geometry, pipette tip seat, tool holder etc.), as this does not take place during the dosing process, but in advance of the application.

The use of two O-rings 24, 25 on each attachment 5 makes it possible to allow unknown tolerance chains due to slight differences in the fit of the pipette tips with the same dosing quality. The process consists of three steps:
According to Fig. 7 Several pipette tips 6 are received on a single or multi-channel pipetting head 1. After the pipette tips 6 have been picked up on the attachments 5 of the pipetting head 1, all pipette tips 6 are at a comparable height and can be pushed onto the attachments 5 a further distance with little effort.

By a dedicated movement in the vertical direction below the soil tolerance range of a surface (e.g. the bottom of a microtiter plate 73) the pipette tips 6 are pressed onto the respective approaches 5 to different extents. With the same orientation of the lugs 5 in the vertical direction, the individual pipette tips 6 have individual heights after this step, which heights were determined by the unknown base geometry and the tolerance chains. This is in Fig. 8 shown.

Then a small movement of the pipetting head 1 upwards creates a gap x between the lower ends 63 of the pipette tips 6 and the surface of the vessel (eg microtiter plate 73). This gap x is required for aspiration of liquid into the pipette tips 6 in order to prevent the pipette tips 6 from blocking. Due to the individual positioning of the pipette tips 6, the lower ends of all pipette tips 6 have the same distance from the surface of the vessel according to this method. This is in Fig. 9 shown.

The advantage of this method is that all (known and unknown) tolerances are completely compensated for in each metering step. Furthermore, this process takes place automatically since it can be carried out by the laboratory automat 70 without additional effort for the user. The method is carried out during a run of the laboratory automat 70 with the individual combinations of pipette tips 6 and the corresponding individual cavities single or multiple vessels (eg microtiter plates 73).

Reference symbol list

1

Pipetting head

2nd

Housing (carrier)

3, 4

Housing shell

5

Neck

6

Pipette tip

7

Mounting plate (carrier plate)

8th

Mounting pin

9

Piston-cylinder unit

10th

cylinder

11

piston

12

External thread

13

inner thread

14

Through hole

15

Housing wall

16

paragraph

17th

upper cylindrical section

18th

lower cylindrical section

19th

conical section

20th

upper devices for axial position securing

21st

upper ring groove

22

lower devices for axial securing of position

23

lower ring groove

24, 25

O-rings

26

inner space

27th

Connection hole

28

Liner

29

drilling

30th

cylindrical piston head

31

Piston head ring groove

32

Housing wall

33

Piston plate

34

channels

35

Canal wall

36

Canal shoulder

37

Slot opening

38

Forehead opening

39

Threaded nut

40

upper pin section

41

Fastener

42

middle pin section

43

lower pin section

44

drilling

45

Longitudinal groove

46

wing

47

spindle

48

thread

49

Bearing journal

50

ball-bearing

51

Bearing bush

52

Bearing bracket

53

Grub screw

54

Carrier

55

slot

56

Dowel pin

57

Scraper plate

58

Through hole

59

Linkage

60

bulge

61

Carrier

62

Tip opening

63

lower end

64

Push-on opening

65

top end

64, 65, 66

conical areas

67

cylindrical extension

68

Sealing seat

70

Laboratory machine

71

Multi-axis transformer (robot arm)

72

Tool holder

73

Microtiter plate

74

adapter

75

Work surface

Claims (15)

A pipetting head for a pipetting device comprising: - a carrier (2), - At least one on the carrier (2) held approach (5) for clamping pipette tips (6) and two O-rings (24, 25) made of an elastomer held on the shoulder (5), - The two O-rings (24, 25) and the shoulder (5) are designed to clamp a pipette tip (6) solely by deforming the two O-rings (24, 25) on the shoulder (5). A pipetting head according to claim 1, wherein the O-rings (24, 25) are made of a soft rubber, silicone or thermoplastic elastomer. Pipetting head according to Claim 1 or 2, in which the extension (5) has devices for axially securing the position (20, 22) which are designed to position each of the two O-rings (24, 25) in a specific upper and in a specific lower position supported and allow deformation of the two O-rings (24, 25) in the radial direction. Pipetting head according to Claim 3, in which the devices for the axial securing of position (20, 22) on the circumference of the attachment are circumferential annular grooves (21, 23) which partially accommodate at least one O-ring (24, 25), or are one or more projections on the circumference of the approach, which receive at least one O-ring (24, 25) between them. Pipetting head according to one of claims 1-4, in which the extension (5) has at least one conical section (19) and / or in which the extension (5) has at least one cylindrical section (17, 18). Pipetting head according to Claims 4 and 5, in which the extension (5) has an upper cylindrical section (17) at the top, a lower cylindrical section (18) at the bottom, a conical section (19) tapering from top to bottom and between the upper cylindrical section Section (17) and the conical section (19) has upper devices for axial position securing (20) and between the conical section (19) and the lower cylindrical section (18) lower devices for axial position securing (22). Pipetting head according to one of claims 1-6, wherein the upper O-ring (24) has a larger inner diameter and / or a cross section with a larger diameter than the lower O-ring (25). Pipetting head according to one of claims 1-7, wherein the diameter of the cross section of the upper O-ring (24) is greater than the depth of the upper annular groove (21) and / or the width of the upper annular groove (21) is equal to or greater than the diameter of the cross section of the upper O-ring (24) and / or the diameter of the cross section of the lower O-ring (25) is greater than the height of the lower ring groove (23) and / or the width of the lower ring groove (23 ) is equal to or larger than the diameter of the cross section of the lower O-ring (25). Pipetting head according to one of Claims 1-8, which has lugs (5) arranged next to one another in parallel in one or more rows. Pipetting head according to one of claims 1-9, in which the lugs (5) are fixedly connected to the carrier (2). Pipetting device or transfer device comprising a pipetting head (1) according to one of Claims 1-10. Pipetting station or automatic pipetting device or automatic laboratory device (70) comprising a pipetting device and / or a transfer device according to claim 11. Use of a pipetting head (1) according to one of claims 1-10, a pipetting device or transfer device according to claim 11 or a pipetting station, an automatic pipetting device or a laboratory machine (70) according to claim 12, in which - A pipette tip (6) is clamped onto each attachment (5) of the pipetting head (1), the pipetting head (1) is displaced until each clamped pipette tip (6) has with its lower end (63) contact with a vessel (73) which is provided on a work surface (75), - The pipetting head (1) is displaced until the lower end (63) of each clamped pipette tip (6) is at a certain distance (x) from a bottom of the vessel (73) and - Liquid from the vessel (73) is taken up in each clamped pipette tip (6). Use according to claim 13, in which the pipetting head (1) is displaced until all the clamped-on pipette tips (6) with the lower ends (63) are simultaneously in contact with the bottom of the vessel (73) and the pipetting head (1) is then displaced, until the lower ends (63) of all pipette tips (6) are at a certain distance from the bottom of the vessel (73). Use according to claim 13 or 14, wherein the pipetting head (1) is a multi-channel pipetting head and the vessel is a microtiter plate (73).

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