PIPETTENSPITZE

Description

[0001] The invention relates to a pipette tip.

[0002] Pipette tips are used together with pipettes and other dispensing devices, particularly in medical, biological, biochemical, and chemical laboratories for dispensing liquids. Pipettes and other dispensing devices are referred to collectively as "pipetting devices" below. Pipette tips have an elongated, tubular body with a lower opening at the bottom for the passage of liquid and an upper opening at the top for clamping onto the attachment of a pipetting device. Pipette tips usually have a generally conical shape, with a cross-section that increases from the lower opening to the upper opening. Standardized conical or tapered tips are well known.frustoconical tips (working cone) with a standard geometry that is used uniformly by many manufacturers and that is characterized for each pipette tip size by a specific mean diameter and a specific cone angle of the conical tip.

[0003] Multi-channel pipetting devices are used to simultaneously aspirate liquid from one or more vessels or dispense it into one or more vessels. They are often used for processing microtiter plates, which contain a large number of vessels arranged in a matrix-like arrangement. For this purpose, multi-channel pipetting devices have several conical attachments arranged parallel to one another in one or more parallel rows, onto which pipette tips can be clamped. Adapted to a frequently used format of microtiter plates with 96 (8 × 12) or 384 (16 × 24) vessels (wells) according to the ANSI standard, multi-channel pipettes with 8, 12, 16, or 24 attachments in a row are known. Multi-channel dispensing devices with a dispensing head with 96 or 384 attachments are also known. Corresponding to the distance between adjacent tubes in microtiter plates with 96 or 384 tubes, adjacent tubes are spaced 9 mm or 4.5 mm apart.

[0004] When designed as an air-cushion pipetting device, the pipetting device has at least one air displacement device that is communicatively connected to a through-hole of at least one attachment. An air cushion can be displaced by means of the displacement device to suck liquid into and expel it from a pipette tip clamped onto the attachment. The displacement device is usually designed as a cylinder with a piston that can be moved within it. Displacement devices with a displacement chamber and at least one deformable wall are also known, with deformation of the wall causing the air cushion to be displaced.

[0005] In the design as a positive displacement pipetting device, a small piston is arranged in the pipette tip, which, when the pipette tip is placed on an attachment, is coupled to a coupling element of a piston drive of the pipetting device, which can be displaced in a through-hole of the attachment.

[0006] The liquid is preferably drawn into the pipette tip in a single step or in several small steps. The liquid is released in a single step when pipetting and in several small steps when dispensing.

[0007] Pipetting devices usually have an ejector that acts on the upper edge of the pipette tip to push it away from the tip hub. In multi-channel pipetting devices, the ejector can be pressed against the upper edges of several pipette tips simultaneously. Using the ejector, the user can separate the liquid-contaminated pipette tips from the tip hub without touching them.

[0008] The pipetting device can be a hand-held pipette that the user can hold and operate with just one hand. It can also be a dispensing station ("pipetting station") or an automated dispensing device ("pipetting automated"), in which a dispensing head with one or more attachments can be moved on a robotic arm or other transfer system above a work surface. The pipetting device can also be part of a laboratory automated device ("workstation") that, in addition to dispensing, can perform other treatments of liquids (e.g., mixing, tempering, analysis).

[0009] To avoid incorrect dosing, the pipette tip must be clamped onto the hub sufficiently tightly and tightly. Furthermore, the forces required to attach and remove the pipette tip from the hub must not be excessive. Conventional pipette tips have thick walls and are rigid in the contact area with the conical hub. When attached, the pipette tips are elastically expanded around the circumference by the hub. The spring characteristic curve is steep, requiring high attachment forces. After attachment, a correspondingly high static friction acts between the hub and the pipette tip, which must be overcome during ejection. The user is exposed to the high forces required to attach and remove the pipette tip. This can trigger illnesses known as cumulative trauma disorders (CTDs).If the attachment and removal is carried out by means of motor drives, these must be sufficiently powerful and have a high power consumption.

[0010] US 6,197,259 describes a pipette tip that can be firmly attached to a pipette hub by applying relatively low axial attachment forces of six pounds (26.7 N) and ejected from the hub by applying relatively low ejection forces of three pounds (13.3 N). The pipette tip has a conical upper end with an inner diameter at the upper end that is larger than the diameter of the pipette hub 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 junction between the upper end and the central section. The central section has a side wall with a wall thickness of between 0.2 and 0.5 mm at and adjacent to the sealing area.The annular sealing portion has an inner diameter smaller than a value "x" and is configured to engage the lower end of a sealing zone of the hub and expand radially when the hub is inserted. This creates a fluid-tight seal between the sealing zone of the hub and the sealing portion of the pipette tip. Furthermore, the pipette tip includes lateral stabilizing means on the inside adjacent to the sealing portion that engage the outer surface of the hub to stabilize the pipette tip on the hub. The lateral stabilizing means include at least three circumferentially spaced contacts extending inwardly from the inner surface of the pipette tip.The diametrical distance between the contacts is dimensioned such that they easily engage the lower end of the hub and allow the lower end to slide past without expanding the side walls of the pipette tip on which the contacts are located. When the lower end of the hub's sealing zone engages the sealing area of ​​the pipette tip, the pipette tip is stretched in and immediately adjacent to the sealing area. When the contacts guide the pipette tip onto the hub, the side wall of the pipette tip deforms inward between the contacts and is not expanded, thereby keeping the force required to press the hub in low. The hub can be pressed deeper into the pipette tip with increasing attachment force. Accordingly, high ejection forces are required to detach the pipette tip from the hub.Due to the inward-protruding contacts, the design is only suitable for relatively large pipette tips.

[0011] US 6,568,288 describes a pipette tip having axially spaced annular sealing zones and substantially cylindrical lateral guide zones, the sealing zone being sufficiently thin to form an interference fit and airtight seal between a sealing surface of the sealing zone and the sealing zone upon penetration by a hub of a pipette having axially spaced annular sealing zones and cylindrical lateral guide zones. The wall thickness in the sealing zone is preferably between 0.2 and 0.5 mm. The sealing surface is the outer surface of an annular, radially outwardly projecting projection adjacent to the lower end of the hub. The pipette tip has an annular, upwardly facing and inwardly directed shoulder on the inner circumference to limit engagement with the hub. The engagement force is said to be approximately two pounds (8.9 N) and the ejection force approximately one pound (4.45 N).The depth stop can result in incomplete immersion when simultaneously picking up multiple pipette tips from a tray or rack using a multi-channel pipetting device. If the tray or rack bends slightly downward between its side edges, placing the two outer tips on the shoulders of the two outer pipette tips can result in insufficient immersion of the other tips into the pipette tips arranged between them.

[0012] US 6,967,004 B2 describes a pipette tip having an annular sealing region with an inner sealing surface on a side wall that is sufficiently thin in the sealing region to expand slightly to form an interference fit and an airtight seal between the sealing surface and a sealing zone of a pipette hub inserted into the pipette tip. The pipette tip has an annular, inwardly and upwardly directed shoulder that limits the insertion of the hub. The hub has two cylindrical sections of different diameters. Its annular sealing zone includes a sealing edge at a junction of the lower end of a cylindrical section and the outermost edge of a radially extending transition of the hub. Preferably, the forces for inserting and ejecting the pipette tip are less than two pounds (8.9 N).The depth stop can lead to insufficient immersion of the samples when picking up several pipette tips at the same time using a multi-channel pipetting device.

[0013] EP 2 138 234 A1 describes a pipette tip which, for detachable connection to the hub of a pipetting device, has a flexible, tubular connecting section at the upper end of an elongated tubular section with a wave-shaped contour in cross-section, which increases the extensibility of the seat area. The seat area can be reversibly extensible by more than 20% when attached to the hub. To ensure a tight fit, the wave-shaped contour must be smoothed out on the hub, which means that further extensibility is only minimal. As a result, the pipette tip requires precise manufacturing. Furthermore, a shoulder projecting radially inwards is present between the seat area and the tubular section, which acts as a depth stop for the hub, which can lead to insufficient immersion of the hubs when picking up pipette tips using a multi-channel pipetting device.

[0014] EP 2 606 977 A1 describes a pipette tip in 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, wherein next to the upper opening on the inner circumference there is a seating area which serves for attachment to a standardized conical attachment of a pipetting device. The seating area has a holding area with radially inwardly projecting, axially extending ribs and, below the holding area, a sealing area with an inwardly projecting sealing projection running around the circumference. The seating area is designed such that when attached to the attachment with an attachment force which ensures that the pipette tip is held and sealed on the attachment, the ribs are partially plastically deformed and an elastic deformation occurs outside the ribs in the seating area.Below the sealing area, it has a braking area that widens conically toward the upper opening to limit the insertion. This ensures a secure seal on the tip of a pipetting device and significantly reduces the ejection force required. The design is particularly suitable for relatively large pipette tips with nominal volumes of 2.5, 5.0, and 10 mL. It is less suitable for smaller pipette tips due to the difficulty of manufacturing the delicate ribs.

[0015] EP 3 115 110 A1 describes a pipette tip with a tube-shaped body and a seating area for attachment to a conical hub of a pipetting device. The seating area has a circumferential, inwardly projecting sealing projection on the inner circumference at a distance from the upper opening. A circumferential braking area tapering downwards more sharply than the hub is located below the sealing projection. A circumferential supporting projection is located above the sealing projection and can be clamped sealingly onto the hub by elastic deformation. The braking area rests further down on the hub and the supporting projection rests further up on the hub without prestressing, or is spaced from the hub by a circumferential gap.The pipette tip seals well and securely clamps onto the tip of a pipetting device, can be ejected from the tip with minimal force, and is also well suited for smaller pipette tip sizes. The disadvantage is that the high force required to clamp it onto the tip and remove it from the tip is still high.

[0016] WO 2011 / 091308 A2 describes a pipette tip that has a circular flange at the proximal end of a proximal section and axially directed ribs in the proximal section, spaced apart from each other in the circumferential direction. The flange is intended to increase the rigidity of the pipette tip and facilitate the alignment of the dispenser to the pipette tip. The ribs are intended to limit the axial expandability of the pipette tip in the proximal region. The attachment 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 2000 g (20 N).

[0017] US Pat. No. 7,335,337 B1 discloses an ergonomically optimized pipette tip that can be securely attached to a pipette while reducing the attachment and ejection forces. The pipette tip has elastic expansion elements that reduce the axial attachment and ejection forces. The elastic expansion elements are arranged in an upper section of the pipette tip above a sealing ring running around the inner circumference. They are formed by outwardly curved regions of reduced wall thickness between cylindrical or conical segments of the pipette tip. When a pipette tip is inserted into the upper opening of the pipette tip, the expansion elements are pulled flat and the segmented wall sections expand. Ribs on the inside of the wall segments guide and align the pipette tip on the tip.However, the insertion forces are still high because the pipette tip has a large wall thickness in the area of ​​the circumferential sealing ring and can only expand slightly, and increase sharply when the expansion elements are drawn flat.

[0018] WO 2018 / 213196 A1 describes a pipette tip with a proximal section having alternating, longitudinal grooves and panels designed to facilitate the expansion and compression of the wall when the pipette tip is attached to a correspondingly designed dispensing device and sealingly engaged therewith. These measures reduce the axial force required to clamp a pipette tip onto a dispensing device and to release a pipette tip from a liquid dispensing device. The grooves are stepped, V-shaped, or U-shaped. A plurality of grooves and panels are arranged alternately around the circumference of the proximal section. To form the grooves, narrow areas and the corners at approximately right angles between the grooves and panels must be filled with plasticized plastic during injection molding.This limits the output and reduces the dimensional stability and strength of the pipette tip. There is also a risk that the pipette tip will tear at the bottom of the grooves when clamped onto the hub and will not seal properly. The pronounced structuring of the proximal section of the pipette tip also makes it difficult to label the pipette tip.

[0019] EP 3 575 000 A1 discloses in Fig. 5a-b a pipette tip made of plastic (cf.

[0045] ), wherein in addition to the upper opening on the inner circumference of the tubular body there is a seating area for the attachment.

[0020] Based on this, the object of the invention is to provide a pipette tip which can be clamped sufficiently firmly and sealingly onto the attachment of a pipetting device with reduced attachment and ejection force, has more favorable manufacturing properties with improved dimensional accuracy and strength and is better suited for labeling different pipette tip types.

[0021] The problem is solved by a pipette tip having the features of claim 1. Advantageous embodiments of the pipette tip are specified in subclaims.

[0022] The plastic pipette tip according to the invention comprises an elongated, tubular body with a lower opening at a lower end of the tubular body for the passage of liquid and an upper opening at an upper end of the tubular body for clamping onto an attachment of a pipetting device, wherein a seating area for the attachment is provided next to the upper opening on the inner circumference of the tubular body, characterized in that the tubular body has a plurality of flattened portions extending in the axial direction on the outer circumference next to the upper opening and the tubular body has the contour of an arc polygon in a cross-section through the flattened portions on the outer circumference.

[0023] The pipette tip according to the invention has a thinner wall thickness in the area of ​​the flattened portions than at the two lateral edges of the flattened portions. This improves the deformability of the pipette tip when clamped onto a pipetting device attachment, so that a secure seal of the pipette tip on the attachment can be achieved even with comparatively low attachment forces. The pipette tip can be designed such that it is exclusively elastically deformed when clamped onto a defined attachment of a pipetting device with a specific force. However, it can also be designed such that it is plastically deformed when clamped onto a defined attachment of a pipetting device with a specific force. During elastic deformation, the attachment force increases proportionally to the deformation. The elastic deformation can be completely reversed once the pipette tip is released from the attachment.When the elastic limit is exceeded, plastic deformation occurs. Plastic deformation is irreversible and does not reverse itself once the pipette tip is removed from the hub. During plastic deformation, the attachment force no longer increases, or only increases slightly, with the deformation. Elastic or plastic deformation occurs preferentially in the area of ​​the flattened portions, since the pipette tip has the thinnest wall thickness in the area of ​​the flattened portions, next to the upper opening. This minimizes the force required to clamp the pipette tip tightly onto the hub. In the case of plastic deformation, the attachment force can be limited to a specified limit.

[0024] In the cross-section through the tubular body, the flattened portions, each with their arc-shaped curved profile, define an outer circumference of the tubular body in the form of an arc polygon. In an arc polygon, the sides are formed by arcs that extend between two adjacent vertices. According to a preferred embodiment, the arc polygon is a regular arc polygon, such as the Reuleaux polygon. An arc polygon is based on a polygon whose sides are replaced by circular arcs between two adjacent vertices, the center of which is the opposite vertex. The intersection (the common area) of the circles forms the arc polygon. The underlying polygon must be convex and must not overlap. A regular arc polygon is based on a regular polygon that has both sides and interior angles of equal length.A special case are polygons of equal thickness, whose underlying polygons have an odd number of corners, so that every possible diameter of the body has the same value (constant width).

[0025] A particular advantage is the good ratio between the thick-walled and thin-walled sections of the cross-section. The thin-walled sections reduce the force required to stretch the pipette tip when clamping it onto a nozzle, thus also reducing the insertion force.

[0026] Due to the increased flexibility, the pipette tip can be better used with attachments of different shapes and / or dimensions. The thick-walled areas can also be advantageously used as a support surface for the pipette ejector, allowing the pipette tip to be safely removed from a attachment. Depending on the design of the pipette tip, the thickened areas can also be used to ensure good support in the tray (pipette tip holder), which has holes into which the pipette tips are inserted and on whose upper edge they are supported by the thickened areas. Thus, the ratio of the thick-walled to thin-walled areas of the cross-section, combined with the reduced stretching force, is particularly advantageous. In addition, the outer contour of the tubular body in the form of an arc polygon can reduce the cross-sectional area and thus the weight of the pipette tip and the plastic material required for production.A further advantage is that the special external appearance of the pipette tips with the outer contour in the form of an arc polygon makes it possible to distinguish between pipette tip types.

[0027] A simulation comparison of a pipette tip with the outer contour in the form of an arc polygon with a conventional hollow cylindrical pipette tip has shown that the stretching force applied to the tip when attaching it can be reduced by up to approximately 35%.

[0028] An advantage of injection molding is that the plastic compound can better fill the cavity in the injection mold in the area of ​​the flats due to the lower pressure loss at the flats than in the area of ​​the grooves of conventional pipette tips. This also reduces weld lines and results in more dimensionally stable and stronger pipette tips. The increased strength prevents the pipette tips from tearing at the points of the thinnest wall thickness due to the insertion forces.

[0029] A further advantage is that the flats can be used to label the pipette tips. In particular, information about the pipette tip and / or its manufacturing process can be applied to the flats during injection molding, for example, the pipette tip size, the material or purity of the pipette tip, the manufacturer, the brand, and / or the production tool used for manufacturing. The pipette tip size is the largest volume that can be dispensed with the pipette tip. Pipette tips that differ from one another by at least one of the aforementioned criteria are also referred to in this application as "pipette tips of different pipette tip types." The marking can be created during injection molding in the form of raised or debossed letters, numbers, characters, or symbols, or can be printed later.User-defined marking is also an option, e.g., by printing, writing with a writing utensil, or affixing a label. Furthermore, the flattened portions themselves can be used as an identifying feature to distinguish between different pipette tip types.

[0030] The flats can also serve as anti-roll protection to prevent a pipette tip placed on a work surface or other surface from rolling away.

[0031] According to one embodiment, the invention relates exclusively to pipette tips in which the sides of the arc polygon are curved outwards, such that the flattened portions have an outwardly (convexly) curved profile in a cross-section through the tubular body. According to another embodiment, in addition to the aforementioned pipette tips, the invention relates to pipette tips in which the sides of the arc polygon are curved inwards, such that the flattened portions have an inwardly (concavely) curved profile in a cross-section through the tubular body. According to a further embodiment, the profile of the flattened portions is largely or exclusively curved outwards or largely or exclusively curved inwards. According to one embodiment of the invention, the radius of curvature is constant along the respective profile. According to another embodiment, the radius of curvature varies along the respective profile or a part thereof.According to another embodiment, the profile of the flats is curved in sections with the same or different curvatures. For example, the profile of the flats is curved outwards or straight at the two edges and curved outwards or inwards between them, so that it is approximately V-shaped overall. According to another embodiment, the profile of the flats is curved differently in sections. The different curvatures can be curves with different radii of curvature or outwards and inwards with the same or different radii of curvature.

[0032] The curvature is the inverse of the radius of curvature of the respective profile.

[0033] According to a further embodiment, the tubular body has, in all cross-sections through the flattened portions, exclusively a curved profile with the same radius of curvature in the flattened portions, or a curved profile with a different radii of curvature in different cross-sections, wherein the curvature of the profile preferably changes gradually from cross-section to cross-section. According to a further embodiment, the flattened portions have an outwardly curved profile and an inwardly curved profile in different cross-sections, wherein the curvature of the profile preferably changes gradually from cross-section to cross-section.

[0034] According to a further embodiment, the wall thickness of the tubular body gradually decreases in a cross-section through the tubular body, starting from one of the two edge regions of each flattened portion in the flattened portion toward its central region. This gradual decrease in wall thickness promotes uniform filling of the cavity in the injection mold and prevents excessive stress when clamping the pipette tip onto a nozzle.

[0035] According to a further embodiment, the flattened portions extend upwards to a distance from the upper end of the tubular body. This allows a circumferential upper edge with a uniform wall thickness to be achieved at the upper end of the pipette tip, which is advantageous for ejecting a pipette tip from the attachment by means of an ejection device of the pipetting device. According to a further embodiment, the upper edge of the pipette tip is a circumferential flange. The flange can be used to hold a pipette tip in a hole of a pipette tip holder ( rack ) can be used.

[0036] According to another embodiment, the flats extend to the upper end of the tubular body. Extending the flats to the upper end is advantageous for deforming the pipette tip with reduced force.

[0037] According to a further embodiment, the tubular body has a shoulder on its outer circumference. The shoulder can be used to support the pipette tip in a hole of a pipette tip holder. According to a further embodiment, the flattened portions extend downwards at least to the shoulder or beyond.

[0038] According to a further embodiment, the tubular body has three to ten, preferably three, four, or five, flattened portions around its circumference. The multiple flattened portions further reduce the force required to deform the pipette tips. Furthermore, different pipette tip types can be identified differently by using pipette tips with different numbers and / or dimensions (e.g., with different widths and / or curvatures) of flattened portions.

[0039] According to another design, all flattenings are of equal width and equally curved.

[0040] According to a further embodiment, the flattened portions run parallel to the central axis of the tubular body or helically around the central axis of the tubular body. In a helical configuration, for example, each flattened portion extends only over a fraction of the circumference of the tubular body or once or more than once around the circumference of the tubular body.

[0041] According to another embodiment, the seating area is conical and / or cylindrical.

[0042] According to a further embodiment, the tubular body has, on the inner circumference of the seat region, at least one inwardly projecting sealing structure extending in the circumferential direction and / or at least one inwardly projecting guide structure extending in the circumferential direction or having a plurality of spaced-apart sections and / or at least one inwardly projecting braking structure extending in the circumferential direction or having a plurality of spaced-apart sections. According to a further embodiment, the sealing structure is a sealing bead and / or the guide structure is a guide bead and / or a guide rib and / or knob- or knob-shaped guide projections and / or the braking structure is a brake bead and / or a conical braking region.

[0043] The sealing structure creates a ring-like contact between the pipetting device hub and the pipette tip, thus ensuring a good seal with low frictional forces when the pipette tip is attached to the hub. Instead of an inwardly projecting sealing structure, the seating area can have a surface seal, for example, formed by a conical or cylindrical surface, or a partially conical and partially cylindrical surface.

[0044] The guide structure creates a ring support or several circumferentially spaced, ring-shaped supports and / or several circumferentially spaced, approximately point-shaped supports between the pipetting device hub and the pipette tip, thus providing good guidance with low friction forces when attaching the pipette tip to the hub. The guide structure holds the pipette tip securely to the hub, even when a force is applied from the side to the lower end of the pipette tip during wall dispensing (liquid dispensing against a vessel wall).

[0045] The braking structure creates a ring-shaped, circular-shaped, or ramp-shaped support between the hub and the pipette tip, slowing the insertion movement of the hub into the pipette tip. The braking effect is determined by the geometry of the braking structure and the hub, as well as the material properties (particularly elasticity and roughness) of the pipette tip and hub.

[0046] According to a further embodiment, the guide structure is arranged above the sealing structure and / or the braking structure is arranged below the sealing structure. According to a further embodiment, the guide structure coincides with the sealing structure and / or the sealing structure coincides with the braking structure. For this purpose, a guide bead can also be designed as a sealing bead and / or a sealing bead can also be designed as a friction bead.

[0047] According to a further embodiment, the tubular body has a plurality of sealing structures and / or guide structures and / or friction structures on the inner circumference, which have a wave-shaped contour in a longitudinal section through the tubular body.

[0048] According to a further embodiment, the tubular body has a widened portion at the upper opening and / or an insertion bevel on the inner circumference. The widened portion and / or insertion bevel facilitate the insertion of a pipetting device attachment into the pipette tip.

[0049] According to a further embodiment, the pipette tip consists exclusively of the tubular body. According to a further embodiment, the pipette tip is an air-cushion pipette tip, i.e., it is designed to be used with an air-cushion pipetting device. According to a further embodiment, the air-cushion pipette tip consists exclusively of the tubular body.

[0050] According to another embodiment, the pipette tip consists of the tubular body and another component. The other component is, for example, a small piston that is arranged inside the tubular body and can be moved within it. This is a positive displacement pipette tip, i.e., a pipette tip that can be used with a positive displacement pipetting device.

[0051] According to a further embodiment, the pipette tip is made of at least one thermoplastic, preferably of at least one polyolefin, preferably of at least one polypropylene and / or polyethylene.

[0052] According to a further embodiment, the pipette tip has one or more of the following features: The wall thickness of the tubular body at the corners of the arc polygon ranges from 0.3 to 1 mm. The seat region is conical on the inside with a diameter that decreases downwards, wherein the cone angle of the seat region is selected from the range of 1° to 6°, preferably from 1.5° to 2.5°. The seat region is designed to be attached to a shoulder, wherein the cone angle of the conical shoulder or the conical section of the shoulder is selected from the range of 1.0° to 10°, preferably from the range of 1.3° to 7°, further preferably from the range of 1.5° to 3°. The sealing structure and / or guide structure and / or brake structure are distributed in the longitudinal direction of the tubular body over the seat region. The wall thickness of the tubular body in the area of ​​the flattened portions (outside the sealing structure and / or guide structure and / or brake structure) is a maximum of 0.3 mm at the thinnest points.the wall thickness of the tubular body in the area of ​​the flattened portions (outside the sealing structure and / or guide structure and / or brake structure) is at least 0.1 mm at the thinnest points, the flattened portions extend in the longitudinal direction of the tubular body over a length of at least 4 mm, the flattened portions extend in the longitudinal direction of the tubular body over at least two sealing structures and / or guide structures and / or brake structures.

[0053] Furthermore, the invention relates to a pipette tip system comprising a plurality of pipette tips according to one of claims 1 to 15 or one of the preceding embodiments, wherein pipette tips of different pipette tip types have differently formed flattened portions and / or different markings on the flattened portions.

[0054] Furthermore, the invention relates to a pipetting system having at least one pipette tip according to one of claims 1 to 15 or one of the preceding embodiments and a single-channel pipetting device having a single attachment for attaching a pipette tip and / or a multi-channel pipetting device having several attachments for simultaneously attaching several pipette tips.

[0055] In the present application, the terms "vertical" and "horizontal", "top" and "bottom" and derived terms such as "above" and "below" refer to an arrangement of the pipette tip with a vertically aligned central axis of the tubular body, with the upper opening at the top and the lower opening at the bottom.

[0056] In the present application, each cross-section through the tubular body is a plane oriented perpendicular to the central axis of the tubular body. Each longitudinal section through the tubular body is a plane in which the central axis of the tubular body extends.

[0057] Furthermore, the central region of the flattening refers to a line or a strip-shaped zone which runs between the two lateral edges of the flattening, wherein the line or zone may have the same distances from the two lateral edges of the flattening or may have different distances from the two lateral edges of the flattening.

[0058] The invention is explained in more detail below with reference to the accompanying drawings of exemplary embodiments. The drawings show: Fig. 1a-a pipette tip with a triangular arc polygon contour in a side view ( Fig. 1a ), a side view rotated by 90° ( Fig. 1b ), a section along the line CC of Fig. 1b (Fig.1c ), a subview ( Fig. 1d ), a top view ( Fig 1e ), a perspective view obliquely from below and from the side ( Fig. 1f ) and a perspective view obliquely from above and from the side ( Fig. 1g ); Fig. 2a-a pipette tip with a triangular arc polygon contour with rounded corners in a side view ( Fig. 2a ), a side view rotated by 90° ( Fig. 2b ), a section along the line CC of Fig. 2b (Fig. 2c ), a subview ( Fig. 2d ), a top view ( Fig. 2e ), a perspective view obliquely from below and from the side ( Fig. 2f ) and a perspective view obliquely from above and from the side ( Fig. 2g ); Fig. 3a-a pipette tip with a quadrangular arc polygon contour in a side view ( Fig. 3a ), a side view rotated by 90° ( Fig. 3b ), a section along the line CC of Fig. 3b (Fig. 3c ), a subview ( Fig. 3d ), a top view ( Fig 3e ), a perspective view obliquely from below and from the side ( Fig. 3f ) and a perspective view obliquely from above and from the side ( Fig. 3g ); Fig. 4a-another pipette tip with a triangular arc polygon contour in a side view ( Fig. 4a ), a side view rotated by 90° ( Fig. 4b ), a section along the line CC of Fig. 4b (Fig. 4c ), a subview ( Fig. 4d ), a top view ( Fig 4e ), a perspective view obliquely from below and from the side ( Fig. 4f ) and a perspective view obliquely from above and from the side ( Fig. 4g ); Fig. 5Superimposed cross-sections through the seating area of ​​pipette tips with a circular cross-section, flats with a straight profile, flats with an inwardly curved profile and flats with the contour of a Reuleaux arc polygon; Fig. 6Simulation of the total deformation during a radial displacement at the inner circumference for pipette tips with different geometries.

[0059] In the following explanation of various embodiments, the structures and components designated by the same designations are provided with the same reference numerals.

[0060] According to Fig. 1 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.

[0061] 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 section 7 at the bottom and a head section 8 above it, which is slightly conical in a lower head section part 8.1 and more strongly conical in an upper head section part 8.2 ( Fig. 1a, 1f Adjacent to the conical section 7, a downwardly directed outer shoulder 10 runs around the underside of the head section 8 on the outer circumference 9 of the tubular body 2.

[0062] The head section 8 of the tubular body 2 is triangular in cross-section and has a flattening 12 with an arcuate outwardly curved profile 13 between each two adjacent corners 11 ( Fig. 1d ). Overall, the tubular body 2, in a cross-section through the head section 8, thus has an outer contour 14 in the form of a regular triangular arc polygon 15, which is also referred to as a Reuleaux triangle. Due to the outer contour 14 in the form of an arc polygon 15 and its circular inner contour 16, the head section 8 has the thickest-walled points 17 at the corners 11 of the arc polygon 15 and the thinnest-walled points 18 in the middle between the corners, with its wall thickness gradually decreasing from the thickest-walled points 17 to the thinnest-walled points 18.

[0063] At the top, the tubular body 2 has a circumferential edge 19 with a corresponding progression of the wall thickness ( Fig. 1g ).

[0064] At the upper end 5, the tubular body 2 has an expansion 21 with an insertion bevel 22 on the inner circumference 20. This is particularly Fig. 1c shown.

[0065] In addition to the upper opening 6, the tubular body 2 has a substantially conical seating area 23 on the inner circumference 20 for a conical attachment 24 of a pipetting device 25. The seating area 23 extends into the head section 8 and has a cone angle of, for example, 2° to 6°. The seating area 23 forms a surface seal for a tight fit of the pipette tip 1 on the attachment 24.

[0066] The tubular body 2 has on the inner circumference 20 below the seat area 23 a circumferential annular groove 26 for holding on the core of an injection molding tool during the production of the pipette tips ( Fig. 1c ).

[0067] At the lower end of the head section 8, the inner contour of the tubular body 2 merges smoothly into the downwardly tapering conical section 7 ( Fig. 1c ).

[0068] For clamping onto the attachment 24 of a pipetting device 25, one or more pipette tips 1 can be held ready in holes of a pipette tip holder, with the shoulder 10 resting on the edge of the holes. Fig. 1c the attachment 24 of a pipetting device 25 can be easily inserted into the pipette tip 1 through the widened portion 21 with the insertion bevel 22 at the upper opening 6. When clamped onto the attachment 24, the pipette tip 1 can be elastically and / or plastically deformed in the area of ​​the flattened portions 12, thereby reducing the attachment forces and achieving a securely sealed fit of the attachment 24 in the seating area 22 with relatively lower attachment forces. The thin-walled areas between the corners 11 lead to a reduction in the required expansion force when attaching the pipette tip 1 to an attachment 24 of a pipetting device 25, as well as to a correspondingly reduced attachment force and increased flexibility when using the pipette tip 1 with a pipetting device 25 that has attachments 23 with different geometries.

[0069] After pipetting liquid, the pipette tip 1 can be easily ejected from the hub 24 because the ejection forces required for ejection are also reduced. For ejection, an ejection sleeve of the pipetting device 25, which is guided on the hub 24, is pressed against the circumferential edge 19 at the upper end 5 of the pipette tip 1 and the pipette tip 1 is stripped from the hub 24. The thick-walled areas at the corners 11 enable safe ejection of the pipette tip 1 because they offer a large contact surface on the upper edge 19 for the attachment of an ejector. Since the thick-walled areas are also formed on the shoulder 10 on the underside of the head section 8, they also ensure good contact with the edge areas of holes in a pipette tip holder. In addition, the cross-sectional shape promotes even stress distribution when attaching it to the hub 24, thereby preventing the pipette tip 1 from tearing open in the head section 8.Finally, the cross-sectional shape in the head section 8 is also advantageous for the uniform filling of the injection mold with plasticized plastic mass during injection molding of the pipette tip 1.

[0070] The pipette tip 1 of Fig. 2 differs from the pipette tip of Fig. 1 in that it has three rounded corners 11 in a cross-section through the head section 8, i.e. corners 11 with a radius 27. The radius 27 is smaller than the radius of curvature of the flattened portions 12.

[0071] The pipette tip 1 of Fig. 3 differs from the pipette tip of Fig. 1 in that, in a cross-section through the head section 9, it has four flattened portions 12 with an arcuate, outwardly curved profile 13, wherein the profiles 13 abut each other at four corners 11. The outer contour of this pipette tip 1 has the shape of a regular, quadrangular arc polygon 15 according to Reuleaux.

[0072] The beneficial effects of the pipette tip of Fig. 1 come from the pipette tip of Fig. 3 due to the increased number of corners 11 and flattenings 12.

[0073] The pipette tip 1 of Fig. 4 is preferably for pipetting smaller filling volumes (e.g. 10 µl) than the pipette tips 1 of Fig. 1 bis 3 (e.g. 200 µl). The pipette tip 1 of Fig. 4 differs from those described above in particular in that the elongated, tubular body 2 has a conical middle section 28 above the conical section 7, a conical transition section 29 above this, and above this a conical head section 8 with a circumferential, radially outwardly projecting flange 30 at the upper end 5. The aforementioned sections 7, 28, 29 and the flange 30 are directly adjacent to one another. The outer diameter of the tubular body 2 generally increases gradually from the lower end 3 to the flange 30. In the middle section, it has small diameter jumps 31 that form level markings. The inner diameter of the tubular body 2 generally also increases gradually from the lower end 3 to the upper end 5 of the tubular body 2.

[0074] The tubular body 2 has, on the inner circumference 20 in the seat area 23, sealing structures 32 in the form of two inwardly projecting, closed, circumferential sealing beads 33, which are spaced apart from one another in the axial direction. The lower sealing bead 33 is also a braking structure 34 in the form of a braking bead 34, which has the function of stopping the insertion of a projection 24 of a pipetting device 25. For this purpose, the lower sealing bead 33 has a smaller inner diameter than the upper sealing bead 33. Above the sealing beads 33, the seat area 23 has a guide structure 36 in the form of several (e.g., 3) guide knobs 37 or guide lugs evenly distributed over the same cross-section on the inner circumference. At the upper end 5, the tubular body 2 has an expansion 21 on the inner circumference 20 with an insertion bevel 22 which ends above the guide structure 36.

[0075] The flange 30 has downwardly projecting ribs 38 on the underside, which extend radially outwards from the head section 8.

[0076] This pipette tip 1 also has three rounded corners 11 with radii 27 and three flattened portions 12 with an arcuate, outwardly curved profile 13 between the corners 11. The flattened portions 12 extend from the underside of the flange 30 in the axial direction of the tubular body 2 to the upper edge region of the transition section 29.

[0077] One or more pipette tips 1 according to Fig. 4 can be provided in a pipette tip holder. They are inserted into holes in the holder and supported by the ribs 38 on the underside of the flange 30 on the edge of the holes. According to Fig. 4c the extension 24 is only partially inserted into the guide structure 36 of the pipette tip 1. The extension 24 is advanced to the sealing and braking bead 33, 35 so that the pipette tip 1 is aligned and clamped sealingly onto the extension 24.

[0078] In Fig. 5 In comparison, the cross sections through the seating area 23 of a hollow cylindrical pipette tip 1.1, a pipette tip 1 with flattened portions 12 with an outwardly curved profile 13 between adjacent cylindrical portions 39, a pipette tip 1.3 with flattened portions 12 with a straight profile 40 between adjacent cylindrical portions 39 and a pipette tip 1.4 with the outer contour of a uniform triangular arc polygon 15 are shown.

[0079] All pipette tips 1.1 to 1.4 have the same maximum outer diameter and the same inner diameter.

[0080] The pipette tip 1.2 with outwardly curved flats 12 has a significantly reduced cross-sectional area and a significantly reduced wall thickness at the thinnest-walled points 17 compared to the hollow cylindrical pipette tip 1.1.

[0081] The pipette tip 1.3 with the straight flats 12 has, compared to the pipette tip 1.2 with the outwardly curved flats 12, an even further reduced cross-sectional area and an even further reduced wall thickness at the thinnest-walled points 17.

[0082] The pipette tip 1.4 with the outer contour of an arc polygon 15 has the smallest cross-sectional area and the smallest wall thickness at the thinnest-walled points 17.

[0083] The following table shows the cross-sectional areas and the radial expansion forces required for a 0.1 mm expansion of the inner circumference for pipette tips with different outer contours in a cross-section through the seating area, as simulated. Furthermore, the table shows the relative force reduction for expansion for each cross-sectional shape compared to the pipette tip with a circular cross-section shown in the second row.

[0084] In the Fig. 6 The deformations (equivalent elastic strain) of the cross-sections of the various pipette tips determined by simulation are shown. The extent of the deformation is indicated by different shades of gray.

[0085] The pipette tip shown in row 1 has the smallest cross-sectional area and requires the least extension force for a radial extension of 0.1 mm, thus achieving the greatest relative force savings. However, according to the figure, the greatest deformations occur with this cross-sectional shape (maximum equivalent extension: 0.77 = 77%), so this pipette tip is prone to tearing.

[0086] The pipette tip in row 2 of the table with the thick circular cross-section has the largest cross-sectional area and the highest extension forces. Fig. 6 the deformation is comparatively small (maximum equivalent strain: 0.60).

[0087] According to rows 3 to 5 of the table, the pipette tips with annular cross-section with 1, 3 or 10 grooves have correspondingly reduced cross-sectional areas and required extension forces, so that a certain relative force saving is achieved. Fig. 6 shows that relatively large deformations (maximum equivalent strain: 0.162; 0.160; 0.139) and stresses occur in the grooves, so that the pipette tips tear easily there.

[0088] The pipette tip with straight flats of line 6 achieves a significantly greater reduction in the cross-sectional area as well as the required extension force and a corresponding relative force saving. Fig. 6 shows that the elastic deformations (equivalent elastic strain: 0.105) and stresses are comparatively low, which protects this pipette tip against tearing in the seating area.

[0089] According to rows 7 to 9 of the table, the pipette tips with the outer contour in the form of an arc polygon have even further reduced cross-sectional areas and reduced expansion forces, as well as an even greater relative force reduction. Fig. 6 the deformations (elastic equivalent strain: 0.83) and stresses in the cross-section are further reduced, providing even better protection against tearing. Bezugszeichenliste

[0090] 1 Pipette tip 2 Tubular body 3 Lower end 4 Lower opening 5 Upper end 6 Upper opening 7 Conical section 8 Head section 9 Outer circumference 10 Shoulder 11 Corner 12 Flattening 13 Curved profile 14 Outer contour 15 Arc polygon 16 Inner contour 17 Thickest wall 18 Thinnest wall 19 Circumferential edge 20 Inner circumference 21 Widening 22 Lead-in bevel 23 Seat area 24 Neck 25 Pipetting device 26 Annular groove 27 Radius 28 Middle section 29 Transition section 30 Flange 31 Diameter projection 32 Sealing structure 33 Sealing bead 34 Braking structure 35 Braking bead 36 Guide structure 37 Guide studs 38 Rib

Claims

1. A pipette tip consisting of plastics material having an elongate, tubular body (2) having a lower opening (4) at a lower end (3) for the passage of liquid and an upper opening (6) at an upper end (5) for being clamped onto an attachment (24) of a pipetting device, wherein a seat region (23) is provided for the attachment (24) next to the upper opening (6) on the inner periphery of the tubular body (2), characterized in that the tubular body (2) comprises multiple flattened portions (12) that extend in the axial direction on the outer periphery (9) next to the upper opening (6) and the tubular body (2) has the contour of a curved polygon on the outer periphery in a cross-section through the flattened portions.

2. The pipette tip according to claim 1, wherein the flattened portions (12) extend in the axial direction at least over part of the seat region (23).

3. The pipette tip according to claim 1 or 2, wherein the flattened portions (12) extend upwards up to a distance from the upper end (5) of the tubular body (2).

4. The pipette tip according to any one of claims 1 to 3, wherein the flattened portions (12) extend up to the upper end (5) of the tubular body (2).

5. The pipette tip according to any one of claims 1 to 4, wherein the flattened portions (12) extend downwards down to a shoulder (10) on the outer periphery (11) of the tubular body (9) or therebeyond.

6. The pipette tip according to any one of claims 1 to 5, wherein the tubular body (2) comprises three to ten, preferably three, four or five flattened portions (12) on the periphery.

7. The pipette tip according to any one of claims 1 to 6, wherein the flattened portions (12) have the same width and / or the same curvature in a cross-section through the tubular body.

8. The pipette tip according to any one of claims 1 to 7, wherein the tubular body (2) has the contour of a regular curved polygon (15) in the cross-section through the flattened portions.

9. The pipette tip according to any one of claims 1 to 8, wherein the flattened portions (12) extend in parallel with the center axis of the tubular body (2) or in a helical manner around the center axis of the tubular body (2).

10. The pipette tip according to any one of claims 1 to 9, wherein the tubular body (2) has a circular contour on the inner periphery (20) in the cross-section through the flattened portions (12).

11. The pipette tip according to any one of claims 1 to 10, wherein the tubular body (2), on the inner periphery (20) of the seat region (23), comprises at least one inwardly projecting sealing structure (32) that extends circumferentially in the peripheral direction and / or at least one inwardly projecting guide structure (36) that extends circumferentially or comprises multiple mutually spaced portions in the peripheral direction, and / or at least one inwardly projecting brake structure (34) that extends circumferentially or comprises multiple mutually spaced portions in the peripheral direction.

12. The pipette tip according to claim 11, wherein the tubular body (2) comprises multiple sealing structures (32) and / or guide structures (36) and / or brake structures (34) on the inner periphery (20) which have an undulating contour in a longitudinal section through the tubular body (2).

13. The pipette tip according to any one of claims 1 to 12, wherein the tubular body (2) comprises a widened portion (21) and / or an insertion slope (22) at the upper opening (6).

14. The pipette tip according to any one of claims 1 to 13, which is manufactured from at least one thermoplastic material, preferably at least one polyolefin, preferably at least one polypropylene and / or ethylene.

15. The pipette tip according to any one of claims 1 to 14, having one or more of the following features: • the wall thickness of the tubular body (2) at the corners of the arc polygon (15) falls in the range of from 0.3 to 1 mm, • the seat region (23) is conical on the inside with a downwardly tapering diameter, wherein the cone angle of the seat region is selected from the range of from 1° to 6°, preferably 1.5° to 2.5°, • the seat region (23) is designed to be fitted on an attachment, wherein the cone angle of the conical attachment (24) or of the conical portion of the attachment is selected from the range of from 1.0° to 10°, preferably from the range of from 1.3° to 7°, more preferably from the range of from 1.5° to 3°, • the sealing structure (32) and / or guide structure (36) and / or brake structure (34) are distributed over the seat region (23) in the longitudinal direction of the tubular body (2), • the wall thickness of the tubular body (2) in the region of the flattened portions (12) (outside the sealing structure and / or guide structure and / or brake structure (34)) is at most 0.3 mm at the thinnest points, • the wall thickness of the tubular body (2) in the region of the flattened portions (12) (outside the sealing structure and / or guide structure and / or brake structure) is at least 0.1 mm at the thinnest points, • the flattened portions (12) extend in the longitudinal direction of the tubular body (2) over a length of at least 4 mm, • the flattened portions (12) extend in the longitudinal direction of the tubular body (2) at least over two sealing structures (32) and / or guide structures (36) and / or brake structures (34).

16. A pipette tip system comprising multiple pipette tips (1) according to any one of claims 1 to 15 or any one of the preceding embodiments, wherein pipette tips of a different pipette tip type have differently designed flattened portions (12) and / or different markings on the flattened portions (12).

17. A pipetting system comprising at least one pipette tip according to any one of claims 1 to 15 and a single-channel pipetting device (25) having a single attachment (24) for fitting a pipette tip (1) and / or a multichannel pipetting device having multiple attachments (24) for simultaneously fitting multiple pipette tips (1).