EP3831485A1 - Pipette tips - Google Patents

Abstract

Pipette tip made of plastic with an elongated tubular body with a lower opening at the lower end for the passage of liquid and an upper opening at the upper end for clamping onto a neck of a pipetting device, with a seating area for the neck next to the upper opening on the inner circumference and on the outer circumference there is at least one groove extending in the axial direction and the tubular body is designed in such a way that, when the pipette tip is put on with a push-on force of the pipette tip with a push-on force less than or equal to a certain limit value, the seat area touches an attachment inside the groove The circumferential direction is plastically stretched, the limit value of the slip-on force having one of the following values

Description

The invention relates to a pipette tip.

Pipette tips are used together with pipettes and other dosing devices in particular in medical, biological, biochemical and chemical laboratories for dosing liquids. In the following, pipettes and other metering devices are collectively referred to as "pipetting devices". Pipette tips have an elongated, tubular body which at the lower end has a lower opening for the passage of liquid and at the upper end an upper opening for clamping onto the neck of a pipetting device. Pipette tips usually have a generally conical shape, the cross section of which increases from the lower opening to the upper opening. Standardized conical or frustoconical attachments (working cone) with a standard geometry which is used uniformly by many manufacturers and which is characterized for each pipette tip size by a specific mean diameter and by a specific cone angle of the conical attachment are known.

Multi-channel pipetting devices are used to simultaneously take up liquid from one or more vessels or to dispense it into one or more vessels. They are often used for processing microtiter plates that have a large number of vessels in a matrix-like arrangement. For this purpose, multichannel pipetting devices have a plurality of conical attachments which are arranged in parallel next to one another in one or more parallel rows and onto which the pipette tips can be clamped. In adaptation to a frequently used format of microtiter plates with 96 (8x12) or 384 (16 x 24) vessels (wells) according to the ANSI standard, multichannel pipettes with 8, 12, 16 or 24 attachments in a row are known. Also known are multi-channel metering devices with a metering head that has 96 or 384 attachments. According to the distance between neighboring vessels of Microtiter plates with 96 or 384 vessels have adjacent attachments at a distance of 9 mm or 4.5 mm from one another.

When designed as an air-cushion pipetting device, the pipetting device has at least one displacement device for air, which is connected in a communicating manner to a through hole of at least one attachment. An air cushion can be displaced by means of the displacement device in order to suck liquid into a pipette tip clamped onto the attachment and to expel it therefrom. The displacement device is usually designed as a cylinder with a piston that can be displaced therein. However, displacement devices with a displacement chamber and at least one deformable wall are also known, a deformation of the wall causing the displacement of the air cushion.

When designed as a positive displacement pipetting device, a small piston is arranged in the pipette tip, which is coupled to a coupling element of a piston drive of the pipetting device when the pipette tip is plugged onto an attachment, which can be displaced in a through hole of the attachment.

The liquid is absorbed into the pipette tip preferably 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.

Pipetting devices usually have an ejector that acts on the upper edge of the pipette tip in order to push it away from the attachment. In the case of multi-channel pipetting devices, the ejector can be pressed against the upper edges of several pipette tips at the same time. By means of the ejector, the user can separate the liquid-contaminated pipette tips from the attachment without touching them.

The pipetting device can be a hand-held pipette which the user can hold and operate with only one hand. It can also be a dosing station ("pipetting station") or an automatic dosing device ("automatic pipetting device") in which a dosing head with one or more attachments on a robot arm or on another transmission system can be displaced above a work surface. The pipetting device can also be part of a laboratory machine ("workstation") which, in addition to dosing, can carry out other treatments of liquids (e.g. mixing, temperature control, analysis).

To avoid incorrect dosing, the pipette tip must be clamped tightly or sealingly onto the attachment. In addition, the forces for attaching and ejecting the pipette tip from the attachment must not be too high. Conventional pipette tips are thick-walled and rigid in the contact area with the conical attachment. When plugging on, the pipette tips are elastically widened at the circumference by the attachment. The spring characteristic is steep, so that high slip-on forces have to be applied. After attaching, there is a correspondingly high static friction between the attachment and the pipette tip, which must be overcome when it is ejected. The user is stressed by the high forces involved in attaching and ejecting the pipette tip. This can trigger diseases that are summarized under the term "cumulative trauma disorders" (CTD). As far as the attachment and ejection takes place by means of motorized drives, these must be correspondingly powerful and have a high power consumption.

The U.S. 6,197,295 describes a pipette tip that can be securely attached to a neck of a pipette by applying relatively low axial push-on forces of six pounds (26.7 N) and by using relatively low ejection forces of three pounds (13.3 N) is thrown from this. The pipette tip has a conical upper end with an inner diameter at the upper end which is larger than the diameter of the attachment of the pipette onto which the pipette tip is to be attached. Furthermore, the pipette tip has a hollow central section and an annular sealing area at the connection between the upper end and the central section. The middle section has a side wall with a wall thickness between 0.2 and 0.5 mm on and next to the sealing area. The annular sealing area has an inner diameter that is smaller than a value "x" and is designed so that it engages the lower end of a sealing zone of the attachment to be expanded radially when the attachment is inserted. This creates a liquid-tight seal between the sealing zone of the attachment and the sealing area of the pipette tip. Furthermore, the pipette tip has lateral stabilizing means on the inside, next to the sealing area, which come into engagement with the outer surface of the attachment in order to stabilize the pipette tip on the attachment. The lateral stabilizing means have at least three contacts spaced from one another in the circumferential direction and extending inward from the inner surface of the pipette tip. The diametrical spacing of the contacts is such that they easily engage the lower end of the hub and allow the lower end to slide past without widening the sidewalls of the pipette tip on which the contacts are arranged. When the lower end of the sealing zone of the attachment comes into engagement with the sealing area of the pipette tip, the pipette tip is stretched in the sealing area and immediately next to it. When the contacts guide the pipette tip on the attachment, the side wall of the pipette tip is deformed inward between the contacts and is not expanded, as a result of which the force that has to be applied to push in the attachment is kept low. The attachment can be pressed deeper into the pipette tip as the push-on force increases. Correspondingly high Ejection forces must be applied to loosen the pipette tip from the attachment. Due to the inward protruding contacts, the construction is only suitable for relatively large pipette tips.

The U.S. 6,568,288 describes a pipette tip that has axially spaced apart annular sealing and essentially cylindrical lateral guide areas, the sealing area being sufficiently thin to provide a press fit and airtight seal when a pipette attachment with axially spaced apart annular sealing and cylindrical lateral guide zones penetrates to form a sealing surface of the sealing zone and the sealing area. The wall thickness in the sealing area is preferably between 0.2 and 0.5 mm. The sealing surface is the outer surface of an annular, radially outwardly projecting projection next to the lower end of the extension. The pipette tip has a circular, upward-facing and inward-facing shoulder on the inner circumference in order to limit the attachment to the attachment. The pushing force should be about two pounds (8.9 N) and about one pound (4.45 N) to throw off. The depth stop can result in incomplete immersion when several pipette tips are picked up from a tray or rack at the same time using a multi-channel pipetting device. If the tray or rack bends slightly downwards between the side edges, placing the two outer attachments on the shoulders of the two outer pipette tips can lead to insufficient immersion of the other attachments in the pipette tips arranged between them.

The US 6,967,004 B2 describes a pipette tip which has an annular sealing area with an inner sealing surface on a side wall which is sufficiently thin in the sealing area to expand slightly and a To form a press fit and an airtight seal between the sealing surface and a sealing zone of a neck of the pipette inserted into the pipette tip. The pipette tip has a circular, inwardly and upwardly directed shoulder that limits the insertion of the attachment. The approach has two cylinder sections with different diameters. Its annular sealing zone includes a sealing edge at a connection between the lower end of a cylinder section and the outermost edge of a radially extending transition of the extension. Preferably, the forces to insert and eject the pipette tip are less than two pounds (8.9 N). If several pipette tips are picked up at the same time by means of a multi-channel pipetting device, the depth stop can lead to insufficient immersion of approaches.

The EP 2 138 234 A1 describes a pipette tip which, for releasable connection with the attachment of a pipetting device, has a flexible, tubular connecting section with a contour that is wave-shaped in cross section at the upper end of an elongated tubular section, which increases the expandability of the seat area. The seating area is reversibly expandable by more than 20% when it is attached to the attachment. For a tight fit, the wave-shaped contour must be drawn smooth on the approach, so that the further elasticity is only low. As a result, the pipette tip requires precise manufacture. Furthermore, there is an inwardly radially projecting shoulder between the seat area and the tubular area, which causes a depth stop for the attachment, which can lead to insufficient immersion of attachments when pipette tips are picked up by means of a multi-channel pipetting device.

The EP 2 606 977 A1 describes a pipette tip with the shape of an elongated tube with a lower opening at the lower end for the passage of liquid and an upper opening at the upper end, being adjacent to the upper Opening on the inner circumference there is a seat area which is used to attach to a standardized conical attachment of a pipetting device. The seat area has a holding area with radially inwardly protruding, axially extending ribs and below the holding area a sealing area with a circumferential, inwardly protruding sealing projection. The seat area is designed in such a way that the ribs are partially plastically deformed when plugged onto the attachment with a push-on force that ensures that the pipette tip is held and sealed on the attachment and an elastic deformation occurs outside the ribs in the seat area. Below the sealing area, it has a braking area that widens conically towards the upper opening to limit attachment. This ensures a secure seal on the attachment of a pipetting device and significantly reduces the ejection force to be applied for ejection. The design is particularly suitable for relatively large pipette tips with a nominal volume of 2.5, 5.0 and 10 mL. It is less suitable for smaller pipette tips due to the difficult production of the filigree ribs.

The EP 3 115 110 A1 describes a pipette tip with a tubular body and a seat area for attaching to a conical attachment of a pipetting device, which has a circumferential, inwardly protruding sealing projection on the inner circumference at a distance from the upper opening, below the sealing projection a circumferential, downwardly stronger than the Approach tapering braking area and above the sealing projection has a circumferential, inwardly protruding support projection. The sealing projection can be clamped onto the projection in a sealing manner with elastic deformation, the braking area resting further down on the projection and the supporting projection resting above the projection without bias or being spaced from the projection by a circumferential gap. The pipette tip seals well and can be securely clamped onto the attachment of a pipetting device, and can be ejected from the attachment with reduced expenditure of force and also works well for smaller pipette tip sizes. The disadvantage is the still high expenditure of force when clamping onto the approach and when stripping from the approach.

The WO 2011/091308 A2 describes a pipette tip which has an annular flange at the proximal end of a proximal section and axially directed ribs in the proximal section which are spaced apart from one another in the circumferential direction. The flange is intended to increase the rigidity of the pipette tip and to make it easier to align the dispenser with the pipette tip. The ribs are intended to limit the axial expandability of the pipette tip in the proximal area. The push-on forces of the pipette tips with 200 µl and 1000 µl filling volumes on five different pipettes are over 1000 g (10 N) and reach up to 2,000 g (20N).

From the US 7 335 337 B1 an ergonomically optimized pipette tip is known which can be reliably fixed on a pipette in which the push-on forces and ejected forces are reduced. The pipette tip has elastic expansion elements by means of which the axial push-on force and ejection force are reduced.

Taking this as a starting point, the invention is based on the object of providing a pipette tip which can be clamped onto an attachment of a pipetting device with reduced push-on force, so that it is held sufficiently firmly or sealingly, and which can be detached from the attachment with reduced ejection force. The pipette tip should be suitable both for use with a multi-channel pipetting device and with a single-channel pipetting device.

The object is achieved by a pipette tip with the features of claim 1. Advantageous embodiments of the pipette tip are specified in the subclaims.

The plastic pipette tip according to the invention comprises an elongated tubular body with a lower opening at the lower end for the passage of liquid and an upper opening at the upper end for clamping onto a neck of a pipetting device, wherein in addition to the upper opening on the inner circumference a seating area for the attachment and on the outer circumference there is at least one axially extending groove and the tubular body is designed in such a way that it is plastically stretched in the circumferential direction with an attachment force less than or equal to a certain limit value with the seat area on an attachment within the groove when the pipette tip is attached where the limit value of the fitting force has one of the following values Pipette tip size (in microliters) Limit value of the attachment force (in N) up to and including 300 5 over 300 up to and including 1,250 10 over 1,250 up to and including 10 ml 25th

The pipette tip size describes the largest volume that can be dosed with the pipette tip. The tubular body in the seat area is weakened by the groove in such a way that it can be plastically expanded in the circumferential direction by being clamped onto the attachment of a pipetting device within the groove. The attachment is designed in such a way that the pipette tip with the seat area can be clamped onto the attachment. For this purpose, the attachment is oversized with respect to at least part of the seat area, so that it forms an oversize fit (press fit) with at least part of the seat area when the pipette tip is clamped on the approach. The plastic deformation within the groove is based on the fact that, when it is pushed onto the shoulder in the wall section of the tubular body inside the groove, the stresses that occur are so high that the elastic limit is exceeded and the plastic deformation occurs. The plastic deformation is an irreversible deformation, ie a deformation that does not recede by itself after the pipette tip is detached from the attachment. In the circumferential direction next to the groove, the tubular body has a greater wall thickness than within the groove. As a result, it is not plastically deformed adjacent to the groove when the plastic deformation occurs inside the groove. In this way, the push-on force can be kept low. The plastic deformation within the groove permanently increases the inner diameter of the tubular body. When the pipette tip is clamped onto the attachment so that it is plastically stretched within the groove in the circumferential direction, the pipette tip is held tightly on the attachment in a sealing manner. The plastic deformation limits the push-on force to values at which the pipette tip is seated sufficiently firmly or sealingly on the attachment. As a result, the push-on force to be applied to the attachment to clamp the pipette tip in a sealing manner and the ejection force required to eject the pipette tip from the attachment are kept low.

In the case of the pipette tip according to the invention, the push-on forces for pushing a pipette tip onto a base can be limited to a certain limit value of. The limit of the insertion force depends on the size of the pipette tip. The pipette tip size is the largest volume that can be dosed with the pipette tip. For pipette tip sizes that fall in the range up to and including 300 µl, the limit value of the insertion force is 5 Newtons. For pipette tip sizes that fall in the range from 300 µl up to and including 1,250 µl, the limit is the Attachment force 10 Newtons. For pipette tip sizes that fall in the range of over 1,250 µl up to and including 10 ml, the limit value of the push-on force is 25 Newtons. It goes without saying that the pipette tip according to the invention can also be attached with an attachment force that exceeds the limit value. The maximum possible push-on force is characterized by the fact that the groove tears. According to one embodiment of the invention, for pipette tip sizes that fall in the range of over 120 μl up to and including 300 μl, the limit value of the push-on force is 5 N. According to a further embodiment, the limit value of the push-on force for pipette tip sizes that fall in the range of over 300 μl up to and including 1,250 μl fall in the range from over 5 N up to and including 10 N, in particular from over 5 N up to and including 7.5 N. According to a further embodiment, the limit value of the push-on force for pipette tip sizes falls in the range of over 1,250 μl up to and including 10 ml fall in the range from over 5N up to and including 25N, preferably from over 5N up to and including 15N, particularly preferably from over 5N up to and including 10N.

The push-on force is applied vertically into the pipette tip. A certain push-on force (of e.g. 5 N, 10 N or 25 N) can be introduced into the pipette tip by pressing it vertically onto a likewise vertically aligned attachment which is supported by a spring on an abutment, the spring so is dimensioned so that it compresses when the specific attachment force is reached. The compression indicates that the attachment force has been reached. Because the pipette tip can do without a depth stop, a multichannel pipette device can be used to pick up several pipette tips in such a way that the attachments in all pipette tips dip deep enough for a secure and tight fit without the push-on forces increasing significantly. According to a preferred embodiment, the pipette tip has no braking area or a braking area that acts as a "gentle" depth stop Approach gradually slows down when dipping into the pipette tip. The pipette tip is particularly suitable for use with a multi-channel pipetting device with 8, 12, 16, 24, 96, 384 or a different number of channels. The pipette tip is particularly suitable for making several available on a tray or rack with a distance between adjacent pipette tips of 4.5 mm or 9 mm for simultaneous reception by means of a multi-channel pipetting device. The pipette tip is therefore particularly suitable for taking up and dispensing liquids from or into a microtiter plate with 384 vessels.

The holding force with which the pipette tip is held on the attachment is identical to or almost the same as the push-on force. A deviation of the holding force from the push-on force can result in particular from the fact that, with the plastic expansion, the tension effective in the circumferential direction in the tubular body decreases somewhat. The ejection force required to eject the pipette tip from the attachment is higher than the holding force because of the resistance to be overcome in the ejection mechanism, in particular the spring force of a return spring. By reducing the holding force, the ejection force is also reduced.

The plastic expansion in the circumferential direction can take place anywhere within the groove or it can be restricted to a section within the groove. The plastic expansion in the circumferential direction within the groove is determined by the shape and dimensions of the tubular body, the shape and dimensions of the groove and the plastic of the pipette tip. The plastic strain can be determined in particular by marking the ends of a section running in the circumferential direction within the groove and measuring the section before and after the pipette tip is attached to the specified attachment with the specified maximum force.

The ends of the line can in particular be marked by the side edges of a line which is applied in the axial direction within the groove by means of an ink pen or fine pen (fineliner) with a defined line thickness. Furthermore, it is possible to determine the plastic deformation by comparing the dimensions of the groove or the base of the groove in the circumferential direction before and after it is attached to the attachment. The dimensions can in particular be measured with the aid of a microscope.

According to one embodiment of the invention, the tubular body is designed in such a way that it can be clamped with the seat area onto a conical attachment or onto a conical section of the attachment. According to a further embodiment, the smallest diameter of the conical extension or of the conical section of the extension is selected from the range from 2 mm to 15 mm, preferably from the range from 2.5 mm to 8 mm, further preferably from the range of 3 mm to 5 mm. According to a further embodiment, the smallest diameter of the conical extension or of the conical section of the extension is 3.34 mm. According to a further embodiment, the cone angle of the conical attachment or of the conical section of the attachment is selected from the range from 1.0 ° to 10 °, preferably from the range from 1.3 ° to 7 °, further preferably from the range of 1, 5 ° to 3 °. According to a further embodiment, the cone angle is 2.17 ° or 2.0 °. According to another embodiment, the tubular body is designed to be plugged with the seat area onto a circular cylindrical extension so that it is plastically stretched in the circumferential direction within the groove.

According to a preferred embodiment, the tubular body is designed in such a way that it fits onto a conical extension or a conical section of the extension can be clamped, the smallest diameter of the conical extension or of the conical section being 3.34 mm and its cone angle being 2.17 ° or 2.0 °.

According to a further embodiment, the tubular body is designed so that it can be clamped with the seat area on a conical extension or on a conical section of the extension which has a mean diameter and a mean cone angle according to one of the following combinations: Pipette size (in µL) Medium diameter approach Approach medium cone angle Pipette tip size (in µL) 10,000 14.3 mm 3.7 ° 10,000 5,000 12.7 mm 2.5 ° 5,000 2,500 9.2 mm 1.8 ° 2,500 1,250 7.2 mm 1.9 ° 1,250 1,000 7.2 mm 1.9 ° 1,000 200 and 300 5.0 mm 7 ° 200 and 300 20 and 100 4.3 mm 5.5 ° 200 10 and 20 3.1 mm 5.5 ° 10 and 20 2.5 2.9 mm 5.5 ° 10

In the table above, under the heading Pipette size, the largest volume that can be dispensed with the pipette is given. If two different pipette sizes are specified in the same line, these are different pipettes whose attachments have the same mean diameter and mean cone angle. The largest volume that can be dosed with the pipette tip is given under the heading Pipette tip size. If two different pipette tip sizes are given in one line, then these are different pipette tips that can be used with the pipettes whose Pipette size is indicated on the same line and corresponds to the pipette tip size. A pipette tip, the tubular body of which is designed for a neck with one of the above combinations of mean diameter and cone angle, has the pipette tip size indicated in the same line as the combination.

According to a preferred embodiment, the approach consists of stainless steel or a hard plastic. According to a further embodiment, the surface of the attachment made of stainless steel or an injection molding tool for injection molding the attachment is polished on the shaping surfaces and has a mean roughness Ra of a maximum of 1 μm, preferably a maximum of 0.5 μm. According to a further embodiment, the ambient temperature when the pipette tip is attached to the attachment is 15 ° C to 30 ° C, preferably 20 ° C.

According to a further embodiment, the groove is designed so that it is plastically stretched in an axially extending strip-shaped section with a width of at most 0.2 mm, preferably at most 0.05 mm, preferably 0.025 to 0.005 mm, preferably 0.011 mm. In this embodiment, the plastic expansion can be checked by measuring the width of a line applied to the strip-shaped section by means of an ink pen or fine pen before and after it is attached to the attachment.

According to a further embodiment, the groove is designed in such a way that when the pipette tip is placed on the attachment it is elastically and plastically stretched in one section by a total of at least 8% with an attachment force that does not exceed the limit value. According to a further embodiment, the groove is designed in such a way that when the pipette tip is pushed onto the attachment is plastically stretched by at least 0.5% in a section with an insertion force that does not exceed the limit value.

According to a further embodiment, the tubular body at the base of the groove has a wall thickness of at most 0.3 mm, preferably at most 0.2 mm and / or in the circumferential direction next to the groove by at least 0.05 mm, preferably at least 0.1 mm, particularly preferably at least 0.15 mm thicker wall thickness than at the groove base. According to a further embodiment, the tubular body has a wall thickness of at least 0.1 mm, preferably of at least 0.25 mm, particularly preferably of at least 0.35 mm, in the circumferential direction next to the groove. The bottom of the groove is that point or that section of the groove at which the groove has the greatest depth in a horizontal cross-sectional plane through the tubular body. According to a preferred embodiment, the tubular body has a wall thickness of a maximum of 0.3 mm, preferably a maximum of 0.2 mm, everywhere at the base of the groove. Preferably pipette tips made of at least one polyolefin, preferably made of at least one polypropylene (PP) and / or polyethylene (PE), which comply with these wall thicknesses, can be plastically stretched in the circumferential direction with the defined maximum force on the defined attachment within the groove, without next to the groove to be plastically stretched.

According to a further embodiment, the tubular body has a wall thickness of at least 0.1 mm at the bottom of the groove. This is advantageous for a sufficiently tight fit of the pipette tip on the attachment. According to a further embodiment, the tubular body has a wall thickness of at least 0.1 mm everywhere at the base of the groove.

According to a further embodiment, the tubular body does not have an annular flange or other radially outwardly protruding and wholly or partially circumferential projection at its upper end.

According to a further embodiment, the tubular body is circular-cylindrical or conical on the outside at the upper section in which the groove is arranged. According to a further embodiment, the conical upper section tapers downwards on the outside of the tubular body. According to a further embodiment, it has a cone angle of a maximum of 8 °, preferably a maximum of 2 °.

The cone angle is defined as the angle between a circular cylindrical guide area on the inner surface of the tubular body and a sealing area on the inner surface of the tubular body.

According to a further embodiment, the groove extends downwards from the upper end of the tubular body. In this way, the plastic deformation of the groove can be facilitated when it is attached to a neck and a sealing clamping of the pipette tip with low push-on forces can be promoted 0.25 mm, particularly preferably at least 0.35 mm. According to a further embodiment, the wall thickness of the tubular body in the circumferential direction next to the groove is everywhere at least 0.05 mm, preferably at least 0.1 mm, particularly preferably at least 0.15 mm thicker than at the groove base. In this embodiment, the tubular body has a wall thickness of at least 0.25 mm everywhere in any horizontal cross-sectional planes through the groove outside the groove.

According to a further embodiment, the tubular body has an inwardly projecting, encircling sealing bead on the inner circumference of the seat area. The sealing bead is advantageous for the firm and sealing seat of the pipette tip on a neck. The insertion and ejection forces are reduced by the sealing bead. In this embodiment, the pipette tip is clamped onto an attachment which is oversized in relation to the sealing bead.

According to a further embodiment, the tubular body has a wall thickness of a maximum of 0.4 mm and / or of at least 0.12 mm in a horizontal cross-sectional plane through the sealing bead at the base of the groove. This is advantageous for limiting the push-on and ejection forces through plastic deformation within the groove and for a sufficiently tight fit of the pipette tip on the attachment.

According to a further embodiment, the groove has a first radius in a horizontal cross-sectional plane through the tubular body with the base of the groove at the deepest point. According to a further embodiment, the flanks of the groove are directly connected to the first radius. According to a further embodiment, the flanks of the groove are each connected to the outer circumference of the tubular body via a second radius.

According to a further embodiment, the first radius is a maximum of 1 mm and / or at least 0.1 mm, preferably 0.25 mm.

According to a further embodiment, the groove has a width of at most 2.5 mm and / or at least 0.25 mm, preferably 0.8 mm, in the circumferential direction. According to a further embodiment, the groove has a length of 2 mm to 40 mm in the longitudinal direction, that is to say essentially parallel to a longitudinal axis of the tubular body which connects the lower opening to the upper opening. This ensures that, on the one hand, there is a sufficient length of the groove to significantly reduce the ejection forces after a plastic expansion at the groove base, and on the other hand it can be ensured that the groove does not lead to leakage problems and / or impermissibly weakens the tubular body, so that there is an increased risk of damage to the tubular body when the tubular body is slipped onto an attachment.

According to a preferred embodiment, the grooves run straight in the longitudinal direction and at least substantially parallel to the longitudinal axis of the tubular body. Alternatively, the grooves can also be designed obliquely or spirally.

According to a further embodiment, the wall thickness of the tubular body in the circumferential direction next to the groove is at least 0.3 mm and / or at most 0.6 mm. This saves material and yet an advantageous rigidity of the pipette tip is achieved.

According to a further embodiment, the sealing bead is arranged at a distance from the upper opening. This makes it easier to introduce the attachment into the pipette tip. To further facilitate insertion, the pipette tip has an insertion bevel at the upper opening on the inner circumference. This has a conical contour that tapers towards the sealing bead.

According to a further embodiment, the distance between the sealing bead and the upper opening is at least 0.1 mm and / or at most 10 mm, for example 0.8 mm. According to a further embodiment, the lead-in bevel has a cone angle in the range from 5 to 25 °, for example 16 °.

The invention relates to pipette tips which have only a single groove extending in the axial direction on the outer circumference.

According to a further embodiment, the tubular body has a plurality of grooves extending in the axial direction on the outer circumference. In this way, a uniform expansion and limitation of the insertion and ejection forces can be achieved. According to a further embodiment, the grooves are evenly distributed over the outer circumference of the tubular body. According to a further embodiment, there are exactly three grooves on the outer circumference of the tubular body.

According to a further embodiment, the at least one groove extends in the circumferential direction of the tubular body over an angular range of up to 120 °, preferably over an angular range of 2 ° to 120 °, further preferably from 3 ° to 25 °, particularly preferably from 5 ° to 15 °. If the pipette tip has only a single groove, the extension in the circumferential direction denotes the extension of the single groove in the circumferential direction. If the pipette tip has several grooves, the extension in the circumferential direction denotes the sum of the extensions of all the grooves in the circumferential direction. The extent of each groove in the circumferential direction is measured between the two lateral edges of the groove base, from which the two groove flanks extend to the outer circumference of the tubular body. The extension of the groove in the circumferential direction limits the push-on force to be applied to the attachment for the sealing clamping of the pipette tip and the elastic expandability of the tubular body set so that when the pipette tip is attached to the attachment, the operator feels an increase in the attachment force until the attachment force required for plastic deformation is reached and receives tactile feedback for the tight clamping of the pipette tip on the attachment. The upper limit of the angular range limits the expandability and avoids the user having to apply the push-on force over a longer distance.

According to a further embodiment, the tubular body has no groove or a groove diametrically opposite an injection point, the upper end of which is arranged below a sealing bead running around the inner circumference of the seat area. This embodiment is based on the knowledge that when the pipette tip is injection molded from plastic, irregularities can occur to a greater extent if the entry point for the plastic into the cavity of the tool for producing the tubular body is arranged diametrically opposite the groove to be formed therein. Then namely the flow fronts starting from the entry point and flowing around the core of the injection molding tool on both sides meet exactly in the area of the weakened wall thickness of the tubular body to be produced. The out-of-roundness can lead to leaks. This is avoided according to the invention in that the tubular body is produced diametrically opposite the point of entry of the plastic into the cavity without a groove or with a groove whose upper end is arranged lower than the point of entry. This can be recognized on the finished pipette tip from the fact that it has no groove diametrically opposite the injection point or a groove whose upper end is arranged lower than the injection point. The injection point is the visually perceptible (eg raised or recessed) point on the outside of the pipette tip where the plastic has entered the cavity. The groove is preferably arranged at least 1 mm, further preferably at least 2 mm, below the injection point.

If the pipette tip has several injection points which are arranged distributed over the circumference of the tubular body, care must be taken accordingly that the flow fronts within the sealing bead do not meet radially inward from a groove. Therefore, according to a further embodiment, the tubular body has no groove extending in the axial direction or a groove extending in the axial direction, the upper end of which is arranged below a sealing bead running around the inner circumference of the seat area, where flow fronts of the plastic compound coming from at least one injection point meet during injection molding .

According to a further embodiment, the tubular body in the seat area is conical on the inside with a diameter that decreases downwards. This is advantageous for clamping onto a conical neck. According to a further embodiment, the seat area has a cone angle of 1.0 to 2.5 °, preferably 1.5 ° to 2 °. The cone angle is defined as the angle between the seat area and a cylindrical guide area on the inside of the tubular body. The flat cone angle is advantageous for the low-friction clamping of the pipette tip onto a neck. The extension preferably has a cone angle which exceeds the cone angle of the seat area, preferably from 1.5 ° to 3 °, further preferably from 2 °.

According to a further embodiment, the tubular body on the inner circumference of the seat area below or above the sealing bead has an inwardly projecting, closed or circumferential guide structure in sections. The term “guide structure” denotes a structure that protrudes on the inner circumference of the seat area, is closed or encircles in sections and serves to support the pipette tip laterally on a projection introduced therein. According to a further embodiment, the guide structure is a guide bead or has a plurality of guide cams distributed in the circumferential direction. The guide structure supports the pipette tip on the side of the attachment so that the pipette tip does not tilt on the attachment, for example when liquid is dispensed when the lower end of the pipette tip comes into contact with a wall of the vessel ("wall dispensing"). The guide structure is preferably dimensioned in such a way that it rests on the attachment without pretension or is spaced from the attachment by a circumferential gap when the pipette tip is clamped onto the attachment. This keeps the forces for attaching the pipette tip onto the attachment low.

According to a further embodiment, the guide structure has a distance from the sealing bead which corresponds at least to the inner diameter of the sealing bead. This is advantageous for guiding the pipette tip by the attachment.

According to a further embodiment, the sealing bead has an inner diameter of a maximum of 3.6 mm, preferably of 3.5 mm, and / or the guide structure has an inner diameter of a maximum of 3.5 mm, preferably 3.4 mm.

According to a further embodiment, the tubular body has a downwardly tapering, conical braking area on the inner circumference of the seat area below the sealing bead, preferably below the guide structure. The "braking area" denotes a downwardly tapering, conical area on the inner circumference of the seat area and below the sealing bead, which serves to gradually brake the attachment of a pipette when it penetrates the pipette tip. The braking area gradually slows down the approach as it penetrates the pipette tip. According to a preferred embodiment, the Brake area available in addition to a management structure. Alternatively, the braking area replaces the guide structure so that it guides the pipette tip at the attachment. According to a further embodiment, the braking area has a cone angle of at least 5 ° and / or of a maximum of 60 °, for example 40 °.

The groove extends in the axial direction at least over part of the height of the seat area. According to a further embodiment, the groove extends in the axial direction over the entire height of the seat area. According to a further embodiment, the groove does not extend in the axial direction beyond the seat area. According to another embodiment, the groove extends in the axial direction beyond the seat area. According to a further embodiment, the groove extends in the axial direction upwards and / or downwards beyond the seat area. According to a further embodiment, the groove extends in the axial direction over the sealing bead. According to a further embodiment, the lower end of the groove is arranged between the sealing bead and the guide structure. According to a further embodiment, the groove extends in the axial direction over the guide structure. According to a further embodiment, the lower end of the groove is arranged at the level of the guide structure. According to a further embodiment, the lower end of the groove is arranged between the guide structure and the braking area. According to a further embodiment, the groove ends at the level of the braking area. According to a further embodiment, the groove extends in the axial direction over the braking area.

According to a further embodiment, the pipette tip has a conical starting section, above it a conical middle section with a smaller cone angle than the starting section and above it a cylindrical or conical head section, optionally between the starting section and the Middle section is a transition section with a larger cone angle than the initial section.

According to a further embodiment, the at least one groove is arranged on the outer circumference of the head section and / or the seat area is arranged on the inner circumference of the head section. According to a further embodiment, the groove extends in the axial direction over the entire height of the head section. According to a further embodiment, the groove ends at the lower end of the head section.

According to a further embodiment, the pipette tip has one of the following pipette tip sizes: 10 µl, 20 µl, 100 µl, 120 µl, 200 µl, 300 µl, 1,000 µl, 1,250 µl, 5 ml, 10 ml. The pipette tip size is the largest volume which can be dosed with the respective pipette tip.

According to a further embodiment, the pipette tip has a pipette tip size (nominal volume) of 2.5 µl to 10 ml, preferably from 10 µl to 1250 µl, particularly preferably from 10 µl, 20 µl or 100 µl.

The pipette tip is preferably made from a single plastic or from several different plastics.

According to a further embodiment, the pipette tip is made from at least one thermoplastic, preferably from at least one polyolefin, preferably from at least one polypropylene (PP) and / or polyethylene (PE).

The pipette tip is preferably manufactured from at least one plastic by injection molding.

According to a further solution to the problem, the pipette tip according to the invention made of plastic comprises an elongated tubular body with a lower opening at the lower end for the passage of liquid and an upper opening at the upper end for clamping onto a neck of a pipetting device, in addition to the upper opening on the inner circumference there is a seating area for the attachment and on the outer circumference there is at least one axially extending groove and the tubular body at the base of the groove has a wall thickness of at most 0.2 mm and in the circumferential direction next to the groove a wall thickness of at least 0.25 mm having.

According to one embodiment, the above pipette tip additionally has the features of one of claims 1 to 17 or one of the further embodiments of this pipette tip described above.

The invention further relates to a pipetting system comprising at least one pipette tip according to the invention according to one of claims 1-17 or one of the above further embodiments and a single-channel pipetting device with a single attachment for attaching a pipette tip and / or a multi-channel pipetting device with several attachments for simultaneous attachment several pipette tips, the multi-channel pipetting device preferably having a dosing head with 8, 12, 16, 24, 96 or 384 attachments.

According to a further embodiment, the at least one extension has at least one conical section, the smallest diameter of this section being selected from the range from 2.0 to 15 mm, preferably 2.5 to 8 mm, further preferably 3 to 5 mm preferably 3.34 mm, and its cone angle is selected from the range from 1.0 ° to 10 °, preferably from is in the range from 1.3 ° to 7 °, further preferably in the range from 1.5 to 3 °, preferably 2.17 °.

According to a further embodiment, the at least one extension is conical or has at least one conical section which has a mean diameter and a mean cone angle according to one of the following combinations: Pipette size (in µL) Medium diameter approach Approach medium cone angle Pipette tip size (in µL) 10,000 14.3 mm 3.7 ° 10,000 5,000 12.7 mm 2.5 ° 5,000 2,500 9.2 mm 1.8 ° 2,500 1,250 7.2 mm 1.9 ° 1,250 1,000 7.2 mm 1.9 ° 1,000 200 and 300 5.0 mm 7 ° 200 and 300 20 and 100 4.3 mm 5.5 ° 200 10 and 20 3.1 mm 5.5 ° 10 and 20 2.5 2.9 mm 5.5 ° 10

In the table above, under the heading Pipette size, the largest volume that can be dispensed with the pipette is given. If two different pipette sizes are specified in the same line, these are different pipettes whose attachments have the same mean diameter and mean cone angle. The largest volume that can be dosed with the pipette tip is given under the heading Pipette tip size. If two different pipette tip sizes are shown in one line, it is are different pipette tips that can be used with the pipettes whose pipette size is specified in the same line and which corresponds to the pipette tip size. A pipette tip, the tubular body of which is designed for a neck with one of the above combinations of mean diameter and cone angle, has the pipette tip size indicated in the same line as the combination.

Fig. 1a-d

eine Pipettenspitze mit 20 µl Nennvolumen in Seitenansicht (Fig. 1a), in einem Längsschnitt (Fig. 1b), in einer vergrößerten Draufsicht (Fig. 1c) und in einer Perspektivansicht von der Seite (Fig. 1d);

Fig. 2a-d

eine Pipettenspitze mit 100 µl Nennvolumen in einer Seitenansicht (Fig. 2a), in einem Längsschnitt (Fig. 2b), in einer Draufsicht (Fig. 2c) und in einer Perspektivansicht von der Seite (Fig. 2d);

Fig. 3

einen Ansatz zum Aufstecken der Pipettenspitze in einer Seitenansicht;

Fig. 4a-d

die Pipettenspitze mit einem Nennvolumen von 20 µl aufgesteckt auf den Ansatz in einem teilweisen Längsschnitt (Fig. 4a), in einem vergrößerten Detail b (Fig. 4b), in einem vergrößerten Teil c (Fig. 4c) und in einem Horizontalschnitt durch den Dichtbereich (Fig. 4 d);

Fig. 5a +

b eine Pipettenspitze vor dem Aufstecken auf den Ansatz (Fig. 5a) und nach plastischer Verformung innerhalb einer Nut (Fig. 5b), jeweils in einem Horizontalschnitt;

Fig. 6a-c

die Pipettenspitze mit einem Nennvolumen von 20 µl auf einer Prüfvorrichtung zum Überprüfen der plastischen Verformung in einer Seitenansicht (Fig. 6a), in ein Vertikalschnitt (Fig. 6b) und in einer Perspektivansicht schräg von der Seite (Fig. 6c);

Fig. 7a + b

Visualisierung der Ergebnisse einer FEM-Verformungsberechnung einer erfindungsgemäßen Pipettenspitze mit Nuten am Außenumfang (Fig. 7a) und einer herkömmlichen Pipettenspitze ohne Nuten am Außenumfang (Fig. 7b), jeweils in einer Perspektivansicht schräg von oben und auf die Seite der Pipettenspitze;

Fig. 8a-d

eine Pipettenspitze mit 20 µl Nennvolumen mit verkürzter Nut gegenüber dem Anspritzpunkt in Seitenansicht (Fig. 8a), in einem Längsschnitt (Fig. 8b), in einem Schnitt entlang der Linie c-c (Fig. 8c) und in einem Schnitt entlang der Linie d-d (Fig. 8d);

Fig. 9a-d

eine Pipettenspitze mit 100 µl Nennvolumen mit einer verkürzten Nut gegenüber dem Anspritzpunkt in einer Seitenansicht (Fig. 9a), in einem Längsschnitt (Fig. 9b), in einem Schnitt entlang der Linie c-c (Fig. 9c) und in einem Schnitt entlang der Linie d-d (Fig. 9d).

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

Fig. 1a-d

a pipette tip with a nominal volume of 20 µl in side view ( Fig. 1a ), in a longitudinal section ( Figure 1b ), in an enlarged plan view ( Figure 1c ) and in a perspective view from the side ( Fig. 1d );

Figures 2a-d

a pipette tip with a nominal volume of 100 µl in a side view ( Fig. 2a ), in a longitudinal section ( Figure 2b ), in a plan view ( Figure 2c ) and in a perspective view from the side ( Fig. 2d );

Fig. 3

an approach for attaching the pipette tip in a side view;

Figures 4a-d

the pipette tip with a nominal volume of 20 µl attached to the attachment in a partial longitudinal section ( Figure 4a ), in an enlarged detail b ( Figure 4b ), in an enlarged part c ( Figure 4c ) and in a horizontal section through the sealing area ( Fig. 4 d) ;

Fig. 5a +

b a pipette tip before attaching it to the attachment ( Figure 5a ) and after plastic deformation within a groove ( Figure 5b ), each in a horizontal section;

Figures 6a-c

the pipette tip with a nominal volume of 20 µl on a test device for checking the plastic deformation in a Side view ( Figure 6a ), in a vertical section ( Figure 6b ) and in a perspective view diagonally from the side ( Figure 6c );

Figures 7a + b

Visualization of the results of an FEM deformation calculation of a pipette tip according to the invention with grooves on the outer circumference ( Figure 7a ) and a conventional pipette tip without grooves on the outer circumference ( Figure 7b ), each in a perspective view obliquely from above and onto the side of the pipette tip;

Figures 8a-d

a pipette tip with a nominal volume of 20 µl with a shortened groove opposite the injection point in side view ( Figure 8a ), in a longitudinal section ( Figure 8b ), in a section along the line cc ( Figure 8c ) and in a section along the line dd ( Figure 8d );

Figures 9a-d

a pipette tip with a nominal volume of 100 µl with a shortened groove opposite the injection point in a side view ( Figure 9a ), in a longitudinal section ( Figure 9b ), in a section along the line cc ( Figure 9c ) and in a section along the line dd ( Figure 9d ).

In the present application, the terms "vertical" and "horizontal", "top" and "bottom" as well as terms derived therefrom such as "above" and "below" relate to an arrangement of the pipette tip with a vertically aligned central axis of the tubular body, where the top opening is at the top and the bottom opening is at the bottom.

According to Fig. 1-2 a pipette tip 1 has an elongated, tubular body 2 which has a lower opening 4 at the lower end 3 and an upper opening 6 at the upper end 5. The lower opening 4 is smaller than the upper opening 6.

In general, the inner and outer diameter of the tubular body 2 increases from the lower opening 4 to the upper opening 6. The tubular body 2 has a conical starting section 7 below, above a middle section 8 with a smaller cone angle than the starting section 7 and above a cylindrical head section 9 with larger outer dimensions than the middle section 8. Adjacent to the middle section 8, a downwardly directed one runs on the underside of the head section 9 on the outside outer shoulder around.

According to Fig. 1 In the case of the pipette tip 1, the conical starting section 7 is connected to the central section 8 via a more conical transition section 10. According to Fig. 2 In the case of the pipette tip 1, the relatively short conical starting section 7 is connected directly to the relatively long central section 8. The wall thickness of the initial section 7 and - only for the pipette tip from Fig. 1 - The transition section 10 increases slightly from bottom to top.

Grooves 11 extending in the axial direction are provided on the outer circumference of the head section. The grooves 11 extend over the entire length of the head section 9, i.e. from the upper end to the lower end of the head section 9. They are aligned parallel to the central axis of the tubular body 2. Each pipette tip 1 has three grooves 11 which are evenly distributed over the outer circumference of the head section 9.

Each groove 11 has a rounded profile in cross section. At the bottom, the groove 11 has a first radius 12 with the center outside the tubular body 2. The first radius 12 merges smoothly on both sides into a second radius 13, 14 with the center within the tubular body 2. Every second radius 13, 14 merges smoothly into the cylindrical outer contour of the head section 9 on the outside.

In addition to the upper opening 6, the tubular body 2 has a seat area 15 for a conical attachment of a pipetting device. The seat area 15 extends into the head section 9 and is conical with a cone angle of 2 °. The tubular body 2 has an inwardly projecting, encircling sealing bead 16 on the inner circumference of the seat area 15. The sealing bead 16 forms the upper end of the seat area 15. An insertion bevel 17 with a conical contour extends from the upper opening 6 to the sealing bead 16. The cone angle of the insertion bevel 17 is 16 °.

The distance between the sealing bead 16 and the upper opening is 0.8 mm. The sealing bead 16 projects 0.05 mm from the seat area 15.

At a further distance from the upper opening 6, the tubular body has an inwardly projecting, closed circumferential guide structure 18 in the form of a guide bead. The guide structure 18 is at a distance of 5.3 mm from the upper opening 6. The guide bead 18 projects 0.03 mm from the seat area 15. Alternatively, instead of the circumferential guide structure 18, point or section-wise circumferential guide structures are provided, for example three guide cams evenly distributed over the inner circumference of the seat area 15.

A conical braking area 19 is provided below the guide structure 18 on the inner circumference of the head section 9. The cone angle of the braking area 19 is 40 °.

A cylindrical cavity 20 is located in the head section 9 below the braking area 19. The cavity 20 can in principle remain free. When executing As a filter pipette tip, one or more filter disks are pressed into the cavity 20 or held in some other way.

At the lower end of the cylindrical cavity 20 there is an inwardly projecting, upwardly directed and circumferential inner shoulder 21. The inner shoulder 21 merges into the central section 8 via a rounded contour.

At the bottom of the grooves 11, the tubular body has a wall thickness of at most 0.2 mm in a horizontal plane through the sealing bead 16 and in the same plane next to the grooves 11 has a greater wall thickness of at least 0.25 mm. In the example, the wall thickness is 0.2 mm at the base of the grooves and 0.4 mm next to the grooves.

The pipette tips 1 are preferably made of polypropylene.

According to Fig. 3 an extension 22 has a rounded insertion section 23 with a circumferential radius 24 of 0.8 mm and a maximum diameter of 3.34 mm, adjoining it a guide section 25 with a small cone angle of 2 ° and a maximum diameter of 3.4 mm, adjoining this is a clamping section 26 with the same cone angle and a maximum diameter of 3.68 mm and adjoining it a cylindrical support section 27. The approach is preferably made of stainless steel or high-strength and rigid plastic, for example from a thermoset.

The extension 22 is through the upper opening 6 in the pipette tip 1 to the in Fig. 4 position shown insertable. In this position, the insertion section 23 is pushed against the braking area 19, the guide bead 18 rests against the guide section 25 and the sealing bead 16 rests against the clamping section 26. This is the inside diameter widened in the seating area 15. The expansion is based on a plastic deformation of the wall of the pipette tip 1 within at least one groove 11. An additional elastic deformation is possible.

According to Fig. 5 an originally 0.011 mm wide strip at the base of the groove 11 is plastically expanded to a width of 0.013 mm by the plastic deformation. The groove 11 is plastically widened from 0.389 mm to 0.402 mm between the turning points of the groove profile on the groove flanks.

It has been observed that the plastic deformation is generally limited to one of the three grooves 11. Obviously, this is based on the fact that during the injection molding of the pipette tip 1, the core of the injection molding tool is displaced somewhat from the center of the cavity, so that the wall thickness in the area of the grooves 11 is slightly different. The shift out of the center is apparently based on the dynamic pressure of the plastic mass flowing into the cavity from the side.

As a result of the plastic deformation when the pipette tip 1 is clamped onto the attachment 22, the clamping force is limited to a value which is sufficient for the sealing and firm seating of the pipette tip 1 on the attachment 22.

The abutment of the guide bead 18 on the guide section 25 prevents a lateral deflection of the pipette tip 1 and thus loosening of its seat on the attachment 22, in particular when dispensing from the wall.

The braking area 19 gently brakes the sliding of the pipette tip 1 onto the attachment 22, which means that when several pipette tips are picked up simultaneously from a tray or rack by means of a multichannel pipetting device, a sufficient amount firm and sealing fit of all pipette tips on all approaches is favored.

According to Fig. 6 For checking the plastic deformation, the pipette tip 1 made of PP is pressed with a defined clamping force onto an attachment 22 made of stainless steel with a polished surface. The push-on force is limited by a helical spring 28, by means of which the extension 22 is supported on an abutment 29. To apply the push-on force, a stopper 30, which receives the lower end of the pipette tip 1 and closes the lower opening in an airtight manner, can be pressed downwards in the direction of the extension 22. The extension 22 is held in a receiving plate 31 which is supported on the upper side of the helical spring 28. The helical spring 28 is set in such a way that it compresses with an attachment force of 3N. Reaching the push-on force of 3 N can be recognized by the compression of the extension 22 or the mounting plate 31. In addition, the abutment 29 can be firmly connected to a stop plate 32 which is arranged above the receiving plate 31 and on which the upper end of the pipette tip rests when an attachment force of 3 Newtons is reached. This limits the push-on force to 3 Newtons. As a result of this push-on force, the pipette tip 1 is clamped onto the attachment 22 in a sealing manner. The pipette tip 1 has plastically deformed at the base of a groove 11. This can be determined by marking a strip at the bottom of the groove and measuring the width of the strip before and after the pipette tip is attached to the attachment 22.

In addition, the tightness can be checked in this arrangement. For this purpose, the pipette tip 1 is hermetically sealed at its lower opening 4 and a vacuum (eg 200 mbar) is applied to its upper opening 6. The tightness is given if, after switching off the vacuum generator, the pressure drop in the pipette tip does not decrease over a certain period of time (e.g. 3.5 seconds) exceeds a certain minimum value (e.g. 1 mbar). The test is carried out at a temperature in the test room of 15 ° to 30 ° C, preferably at 20 ° C.

Figure 7a and b show the deformations of a pipette tip 1 according to the invention and a conventional pipette tip 1 with a wall thickness that is constant in the circumferential direction when a defined radial force is introduced into the seat area 15 according to FEM calculations. The height of the deformation is indicated by colors, whereby the values of the deformation are assigned to the colors in the legend. The contours of the deformed pipette tips 1 are graphically overdrawn and entered in color. Additional lines indicate the contours of the undeformed pipette tips 1.

The greatest deformations caused by the push-on forces acting radially on the seat areas 15 occur in the vicinity of the upper openings 6 of the pipette tips 1. In the pipette tip 1 according to the invention, they are concentrated on the grooves 11. Since this is a calculation, all grooves 11 are equally affected. In the pipette tip 1 according to the invention, the deformations at the grooves are 6.5 times as high as in the conventional pipette tip 1. The deformations within the grooves 11 have plastic and elastic components. Otherwise, the deformations are elastic.

The pipette tip 1 of Fig. 8 differs from the pipette tip of Fig. 1 and the pipette tip 1 of Fig. 9 differs from the pipette tip of Fig. 2 in each case in that only two grooves 11 extend over the entire length of the head section 9 and the groove 11.1 only extends over part of the length of the head section 9. The upper end of the groove 11.1 is namely arranged at a distance from the upper end of the pipette tip 1. With this pipette tip the injection point 33 is arranged exactly in a vertical sectional plane through the central axis of the pipette tip 1, in which the groove 11.1 also runs. Because the groove 11.1 is at a distance from the upper edge of the pipette tip 1, the wall of the head section 9 is diametrically opposite the injection point 33 and is not weakened in the same horizontal plane. As a result, the dimensional accuracy or roundness of the sealing bead 16, which is located near the cross-sectional plane of the injection point, is not significantly impaired by the injection molding.

List of reference symbols:

1

Pipette tip

2

tubular body

3

lower end

4th

lower opening

5

top end

6th

upper opening

7th

Initial section

8th

Middle section

9

Head section

10

Transition section

11

Groove

12th

first radius

13, 14

second radius

15th

sitting area

16

Sealing bead

17th

Lead-in bevel

18th

Management structure

19th

conical braking area

20th

cylindrical cavity

21

inner shoulder

22nd

approach

23

Lead-in section

24

circumferential radius

25th

Guide section

26th

Clamping section

27

cylindrical support area

28

Coil spring

29

Abutment

30th

Plug

31

Mounting plate

32

Stop plate

33

Injection point

Claims (18)

Pipette tip made of plastic with an elongated tubular body (2) with a lower opening (4) at the lower end (3) for the passage of liquid and an upper opening (6) at the upper end (5) for clamping onto a neck ( 22) of a pipetting device, in addition to the upper opening (6) on the inner circumference a seat area (15) for the extension (22) and on the outer circumference at least one groove (11) extending in the axial direction and the tubular body (2) so is designed so that when the pipette tip is plugged in, it is plastically stretched in the circumferential direction with the seat area (15) on an attachment within the groove (11) with a plug-on force less than or equal to a certain limit value, the plug-on force limit value having one of the following values Pipette tip size (in microliters) Limit value of the attachment force (in N) up to 300 5 over 300 to 1,250 10 over 1,250 to 10 ml 25th Pipette tip according to Claim 1, in which the at least one groove (11) extends downwards from the upper end of the tubular body (2). Pipette tip according to Claim 1 or 2, in which the tubular body (2) at the base of the groove (11) has a wall thickness of at most 0.2 mm and / or of at least 0.15 mm and / or in which the tubular body (2) in the circumferential direction next to the groove (11) has a wall thickness of at least 0.25 mm. Pipette tip according to one of Claims 1 to 3, in which the tubular body (2) has an inwardly projecting, encircling sealing bead (16) on the inner circumference of the seat area (15). Pipette tip according to Claim 4, in which the sealing bead (16) is arranged at a distance from the upper opening (6). Pipette tip according to one of Claims 1 to 5, in which the tubular body (2) has an insertion bevel (17) at the upper opening (6) on the inner circumference. Pipette tip according to one of Claims 1 to 6, in which the tubular body (2) has several, preferably three, grooves (11) on the outer circumference. Pipette tip according to Claim 7, in which the grooves (11) are distributed uniformly over the outer circumference of the tubular body (2). Pipette tip according to one of Claims 1 to 8, in which the tubular body (2) has no groove (11) extending in the axial direction there or a groove (11) extending in the axial direction, the upper end of which is below one on the inner circumference of the seat area (15) circumferential sealing bead (16) is arranged, where flow fronts of the plastic compound coming from at least one injection point (33) meet during injection molding. Pipette tip according to Claim 9, in which the tubular body (2) has no groove (11) or a groove (11) diametrically opposite an injection point (33), the upper end of which is arranged below a sealing bead (16) running around the inner circumference of the seat area (15). Pipette tip according to one of Claims 3 to 10, which has an inwardly projecting, closed or circumferential guide structure (18) below the sealing bead (16). Pipette tip according to Claim 11, in which the guide structure (18) is at a distance from the sealing bead (16) which corresponds at least to the inner diameter of the sealing bead (16). Pipette tip according to one of Claims 1 to 12, in which the tubular body (2) on the inner circumference of the seat area (15) below the sealing bead (16), preferably below the guide structure (18), has a downwardly tapering, conical braking area (19). Pipette tip according to one of claims 1 to 13, which has a conical starting section (7), above it a conical middle section (8) with a smaller cone angle than the starting section (7) and above it a cylindrical or conical head section (9), optionally between the Starting section (7) and the middle section (8) a transition section (10) with a larger cone angle than the starting section (7) is present. Pipette tip according to Claim 14, in which the at least one groove (11) is arranged on the outer circumference of the head section (9) and in which the seat area (15) is arranged on the inner circumference of the head section (9). Pipette tip according to one of Claims 1 to 15, which is made from at least one thermoplastic, preferably from at least one polyolefin, preferably from at least one polypropylene and / or polyethylene. Pipette tip according to one of Claims 1 to 16, having one or more of the following features: • the base of the groove (11) has a first radius and the flanks of the groove (11) are directly connected to the first radius, • the first radius is a maximum of 1 mm and / or at least 0.1 mm, preferably 0.25 mm, • the groove (11) has a maximum width of 2.5 mm and / or at least 0.25 mm, preferably 0.8 mm, in the circumferential direction, • the wall thickness of the tubular body (2) in the circumferential direction next to the groove (11) is at least 0.3 mm and / or a maximum of 0.6 mm, • the distance between the sealing bead (16) and the upper opening (6) is at least 0.1 and / or a maximum of 4.0 mm, • the lead-in bevel (17) has a cone angle in the range from 5 to 25 °, • the seat area (15) is conical on the inside with a downwardly decreasing diameter, the cone angle preferably being 1.5 to 2.5 °, preferably 2 °, • the sealing bead (16) has an inner diameter of a maximum of 3.54 mm, preferably of 3.52 mm, and / or the guide structure (18) has an inner diameter of a maximum of 3.42 mm, preferably 3.4 mm. Pipetting system comprising at least one pipette tip according to one of Claims 1 to 17 and a single-channel pipetting device with a single attachment for attaching a pipette tip and / or a multi-channel pipetting device with several attachments for the simultaneous attachment of several pipette tips.

Images