EP3471882A1 - Pipetting system tip having double conicity - Google Patents

Abstract

In order to increase the compatibility of a pipetting system tip with the various types of cones, the invention provides that this tip (6) comprises: -a first group of first cone retention elements (24-1a) defining a larger external diameter (Dmax1); -a second group of second cone retention elements (24-2a) defining a larger external diameter (Dmax2); -a third group of third cone retention elements (24-3a) defining a larger external diameter (Dmax3). The diameter (Dmax1) and the diameter (Dmax2) being different so as to together define a first tip portion (6a) having a first conicity (Con1), and the diameter (Dmax2) and the diameter (Dmax3) being different so as to together define a second tip portion (6b) having a second conicity (Con2) smaller than the first.

Description

 PIPETTING SYSTEM TIP

 PRESENTING A DOUBLE CONICITY

DESCRIPTION TECHNICAL FIELD

The present invention relates to the field of multichannel pipetting systems such as automated pipetting systems called robots, and single-channel or multichannel sampling pipettes, also known as laboratory pipettes, or air displacement liquid transfer pipettes. for calibrated sampling and introduction of liquid into containers. Such pipettes, whether manual, motorized or hybrid, are intended to be held in hand by an operator during the operations of sampling and dispensing liquid.

 The invention relates more particularly to the design of the tips of these pipetting systems, the tips being intended to carry the sampling cones forming consumable elements.

STATE OF THE PRIOR ART

From the prior art, it is known multichannel sampling pipettes having a design of the type incorporating a body forming a handle, and a lower part having at its end several tips cone sampling, whose known function is to wear sampling cones, also called consumables.

On conventional pipettes, each tip comprises two annular cone holding portions each protruding on the outer surface of the tip, and spaced apart from each other in an axial direction of the tip. The upper, bead-shaped holding portion essentially fulfills the function of frictionally holding the cone and limits the introduction of the latter into the mouthpiece. The lower portion, although also involved in maintaining the cone, fulfills the sealing function between the sampling cone and the nozzle. Together, the two holding portions ensure the centering of the tip and the cone.

 This design is the one encountered for decades on pipettes.

 Nevertheless, it has recently been proposed a new design to enhance the ergonomics of the operation of fitting cones. This design is described in document FR 3,026,658. It provides a lip seal on the tip to seal with the sampling cone, as well as two cone holding portions disposed on either side of the seal. . As a result, the contact force between the cone and the tip at the two holding portions may be small, since these portions are no longer used to obtain the seal. The cone fitting force is advantageously reduced, and little impacted by the cooperation between the cone and the lip seal, because of the intrinsic flexibility of the latter. As an indication, with such a design, an axial fitting force of the order of 5N per tip is sufficient to obtain a seal and proper maintenance of each cone of the multichannel pipette. For example, satisfactory results are obtained with an axial fitting force of the order of 40N, on a multichannel pipette with eight tips.

 The operation of fitting cones is thus more ergonomic, limiting the risk of musculoskeletal disorders (MSD) to operators.

 Thus, this design has the particularity of dissociating the means of the nozzle dedicated to the mechanical maintenance of the cone by friction, and those dedicated to obtaining the seal, formed by a lip seal, whose bending force of the lip is substantially less than the compression force of a conventional O-ring.

In addition, by axially shifting the two holding portions, they provide a long centering which also ensures a perfect lateral retention of the sampling cone, able to withstand the radial stresses likely to be encountered during the manipulation of the pipette , during pipetting operations. Finally, the fact of inserting the joint between these two protruding holding portions, that is to say forming a relief on the outer surface of the tip, provides an optimization of the axial length of the tip.

 In view of the above, it is noted that the solution of the document FR 3

026 658 provides an answer to the need of reduction of the fitting force / ejection force, while guaranteeing the tightness and the mechanical resistance of the cones, even when they are stressed. Such mechanical stressing occurs for example during a "licking" movement performed by the operator, during which the ends of the cones scrape the inner surface of a well in order to transfer the last drop of liquid likely to be retained by capillarity at the end of the consumable. In this case, it is important to maintain the mechanical strength of each cone, in particular to ensure that they remain parallel to each other during scraping on successive wells.

 It is furthermore noted that in order to promote the radial deformation of the flange of the sampling cone without increasing the fitting force, the annular holding portions may be made using spaced apart point elements, such as this is also mentioned in the document FR

3 026 658. This is a technique that can strengthen the mechanical strength of the cone, without increasing the fitting force.

 More generally, the solution of document FR 3,026,658 is based on the presence of a seal arranged between two holding / mechanical retaining zones of the sampling cone, which can be applied to a single-channel pipette, even if it is of particular interest for multichannel pipettes.

In any case, there remains a need for optimizing pipette tips, aiming to benefit from the advantages mentioned above while widening the compatibility of the tip with the different types of consumables, in particular with the different flange conicities. encountered on the sampling cones available on the market. In addition, this need exists in a similar way for robots, also intended to work with consumables of different shapes. STATEMENT OF THE INVENTION

To at least partially meet this need, the invention firstly relates to a taper cone holder for the lower part of the pipetting system, the tip having a longitudinal axis forming a first fictitious plane.

 According to the invention, the tip comprises successively from bottom to top along its longitudinal axis, projecting radially outwardly from an outer surface of the tip:

 a first group of first withdrawal cone holding members spaced apart from one another along a first annular zone of the endpiece, two of said first retaining elements being arranged in a second fictitious plane orthogonal to the first imaginary plane, and defining an outer diameter of larger size, said first maximum outer diameter;

 a second group of second sampling cone holding members spaced apart from one another along a second annular zone of the nozzle, two of said second retaining elements being arranged in said second dummy plane and defining an outer diameter of larger dimension, said second maximum outer diameter;

 a third group of third sampling cone holding members spaced apart from each other along a third annular zone of the nozzle, two of said third retaining elements being arranged in said second dummy plane and defining an outer diameter of larger dimension, said third maximum outer diameter.

 In addition, the tip also carries a seal arranged between the first and the third annular zone of the tip.

Finally, firstly the first maximum outer diameter and the second maximum outer diameter are different so as to jointly define a first tip portion having a first taper, and secondly the second maximum outer diameter as well as the third maximum outside diameter are different so as to jointly define a second tip portion having a second taper less than the first taper.

 The invention is remarkable in that it makes it possible to define two portions of nozzle which succeed one another axially and which therefore have different conicities, which can adapt to a wide variety of sampling cones. Depending on its geometry, the cone will be retained by friction by the first and second groups of retaining elements, or by the second and third groups of retaining elements, while cooperating with the seal to seal . In all cases, the double mechanical retention of the cone, by friction, ensures a satisfactory maintenance of the latter, in particular during a movement of "licking" on well made by the operator.

 Thanks to the invention, the range of use of such endpieces is widely extended, without compromising on the maintenance, alignment and sealing of the sampling cones, nor on the intensity of the fitting force to be produced. when coupling between the tip and the cone.

 The invention also relates to a lower portion of a pipetting system comprising at least one such taper cone holder.

 This lower part may be intended for a single-channel pipetting system, and then comprise a single sampling cone tip.

 Alternatively and preferentially, the lower part of the pipette is intended for a multichannel pipetting system, and comprises a plurality of sampling tip-cone tips having longitudinal axes forming part of said first fictitious plane.

 The invention has at least one of the following optional features, taken alone or in combination.

The first retaining elements of the first group, with the exception of said first two retaining elements defining the first maximum outer diameter, are located radially inwardly and at a distance from a first imaginary circle defined by said first maximum outer diameter. This non-axisymmetrical design makes it possible to deform the flange of a cone in a non-circular manner by means of the first two retaining elements defining the first maximum outside diameter. It advantageously results an even greater extension of the range of use of the tip.

 In this case, it is for example made that in addition to said two first retaining elements defining the first maximum outer diameter, one or more pairs of first retaining elements defining one or more diameters smaller than the first outer diameter. maximum, including at least a first lower diameter located in said first fictitious plane. This allows a substantially elliptical deformation of the flange of a cone, for an increase in the range of use of the tip which is then able to adapt to various conic flanges.

 Similarly, the third retaining elements of the third group, with the exception of said two third retaining elements defining the third maximum outer diameter, are located radially inwards and away from a third imaginary circle defined by said third maximum outside diameter. Here again, it is preferentially provided that the third group comprises, in addition to said two third retaining elements defining the third maximum outer diameter, one or more pairs of third retaining elements defining one or third diameters smaller than the third maximum outer diameter, among which at least a third lower diameter located in said first fictitious plane.

 Preferably, the second retaining elements of the second group are located on a second imaginary circle defined by said second maximum outside diameter. Nevertheless, a non-axisymmetric solution such as that described above for the first and third groups could be adopted for the second group, without departing from the scope of the invention.

Nevertheless, in the axisymmetric solution, it is preferably made so that the second group comprises, in addition to said two second retaining elements defining the second maximum outside diameter, one or more pairs of second retaining elements defining one or more other second diameters. outermost ones, including at least one second maximum outside diameter located in said first fictitious plane. Preferably, the first conicity is between 3 and 4.5 °, and in that the second conicity is between 2 and 3.4 °.

 Preferably, for a multichannel pipetting system, the number of tips is between 2 and 16, and even more preferably between 8 and 12.

 To limit the fitting force, the seal is preferably a lip seal. However, it could be an O-ring, without departing from the scope of the invention.

 The invention also relates to a pipetting system comprising a lower part as described above, said pipetting system being a manual, motorized, or hybrid sampling pipette, or this system being an automated pipetting system, said robot.

 Finally, the invention relates to an assembly comprising such a pipetting system, and at least one sampling cone mounted on the tip and retained thereon by friction with the first and second retaining elements, or with the second and third retainers.

 Other advantages and features of the invention will become apparent in the detailed non-limiting description below.

BRIEF DESCRIPTION OF THE DRAWINGS This description will be made with reference to the appended drawings among which;

 FIG. 1 represents a front view of a multichannel sampling pipette with air displacement, according to the invention;

 - Figure 2 shows a partial view and enlarged in longitudinal section of one of the tips of the pipette shown in the previous figure, before the fitting of a sampling cone;

FIGS. 3a to 3c show cross-sectional views taken along lines 11a-11a to 11c-11c of FIG. 2; - Figure 4 is a view similar to that of Figure 2, wherein the cone-tip assembly has been shown in an operating position and with a cone having a first conicity;

 FIGS. 5a and 5b show cross-sectional views taken along the lines Va-Va and Vb-Vb of FIG. 4;

 - Figure 6 is a view similar to that of Figure 2, wherein the cone-tip assembly has been shown in an operating position and with a cone having a second cone;

 FIGS. 7b and 7c show cross-sectional views taken along the lines VII b-VI b and Vllc-VIIc of FIG. 6; and

 - Figure 8 shows a perspective view of a single-channel sampling pipette, according to the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring first to Figure 1, there is shown a multichannel sampling pipette 1, according to a preferred embodiment of the present invention. Nevertheless, the invention is not limited to multichannel pipettes, but applies analogously to "single channel" pipettes, such as the pipette shown in FIG.

 The pipette 1 with air displacement, manual or motorized, comprises in the upper part a handle body 2, as well as a lower part 4 also object of the present invention, incorporating at its lower end cone bearing tips pipette 6, on which cones or consumables 8 are to be fitted. Each cone 8 and its associated end 6 form an assembly also suitable for the present invention.

The sample cone-holder tips 6 are spaced from one another in a lateral direction of the pipetting system, or the pipette lateral direction, represented by the arrow 10. Each nozzle 6 has a longitudinal axis 7, also called a central axis, orthogonal to the direction 10. All the longitudinal axes 7 are parallel and inscribed in a first fictional plane PI parallel to the direction 10. In in addition, a second dummy plane P2 has been represented in FIG. 1, this second plane P2 being orthogonal to the first plane PI and parallel to a central pipette longitudinal axis 14.

 Subsequently, it will be considered that each tip 6 is associated with a first fictional plane PI and a second fictional plane P2 interspersed at the longitudinal axis 7 of the tip concerned. In the plane P2, there is also a direction 15 of movement of the pipette by the operator during a movement called "licking", during which the pipette is moved step by step over successive lines of wells. a plate, to dispense the liquid previously taken from the pipette. In this regard, it is noted that the number of tips 6 is preferably between 8 and 12, and that the plate used has as many rows of wells, and a number of lines adapted for example to reach 384 wells.

 Each nozzle 6 has a through orifice 12 communicating at its upper end with a suction chamber (not visible in Figure 1), and at its lower end with a sampling cone 8. The through hole 12 is centered on its tip 6 associated, that is to say, it is centered on the longitudinal axis 7 of the tip on which is centered the grip cone 8.

 As is known to those skilled in the art, the lower part 4 is preferably mounted in a screwed manner on the body 2 forming a handle. In known manner, the lower part 4 comprises a fixed body 16 covered by an outer removable cover 17, and at its lower end, the end pieces 6. The movable inner parts of this lower part 4 are conventional, and will not be further described . They concern in particular a plurality of pistons parallel to the axis 14 and each associated with a tip 6.

 One of the particularities of the invention resides in the design of the lower part 4, and in particular of its end pieces 6, one of which will now be detailed with reference to FIGS. 2 to 3c representing a preferred embodiment. The other tips 6 of the pipette have an identical or similar design, being reminded that all the tips are parallel and inscribed in the first fictitious plane Pl.

The tip 6, at its lower end, has an outer surface 20 of cylindrical or frustoconical overall shape, narrowing downwardly. In general, the tip is equipped with four zones of cooperation with the cones that it is likely to receive, these zones being spaced apart from one another along the longitudinal axis 7.

 First, there are three groups of friction retaining elements of the sampling cones. The lowest group is the first group, having first retainers arranged projecting radially outwardly from a first area 20-1 of the surface 20, and circumferentially spaced from each other. It is here four first retaining elements, among which two first retaining elements 24-la arranged in the second dummy plane P2, and defining an outer diameter of larger dimension, said first maximum outside diameter Dmaxl. This diameter Dmax1 defines a first imaginary circle C1 centered on the axis 7 and inside which are circumscribed two other first retaining elements 24-lb, radially away from this same circle. The two elements 24-lb together form a pair which defines a first smaller diameter Dinfl of smaller dimension than that of the diameter Dmaxl. This diameter Dinfl is orthogonal to the diameter Dmaxl, and located in the first imaginary plane Pl.

 It is indicated that in the figures, the retaining elements have voluntarily been enlarged for the sake of clarity. In reality, these are simple reliefs having a small height h of the order of 0.2 to 0.7 mm, this height h corresponding to the distance projecting from the outer surface 20.

Then, there is provided a second group comprising second retaining members arranged projecting radially outwardly from a second zone 20-2 of the surface 20, and spaced circumferentially from each other. It is here four second retaining elements, among which two second retaining elements 24-2a arranged in the second dummy plane P2, and defining an outer diameter of larger dimension, said second maximum outside diameter Dmax2. This diameter Dmax2 defines a second imaginary circle C2 centered on the axis 7 and on which there are also two other second retaining elements 24-2a. These two other elements together form a pair which defines another second maximum outside diameter Dmax2, located in the fictitious first plane Pl. Thus, the two maximum outside diameters Dmax2 are of the same size, and, more generally, all the second retaining elements 24-2a are inscribed on the same second imaginary circle C2.

 The highest group on the tip is the third group, having third retainers arranged projecting radially outwardly from a third zone 20-3 of the surface 20, and spaced circumferentially from each other . These are four third retaining elements, including two third retaining elements 24-3a arranged in the second dummy plane P2, and defining an outer diameter of larger dimension, said third maximum outside diameter Dmax3. This diameter Dmax3 defines a third imaginary circle C3 centered on the axis 7 and inside which are circumscribed two other third retaining elements 24- 3b, at a distance radially from this same circle. The two elements 24-3b together form a pair which defines a third lower diameter Dinf3 of smaller dimension than that of the diameter Dmax3. This diameter Dinf3 is orthogonal to the diameter Dmax3, and located in the first imaginary plane Pl.

 Furthermore, the fourth zone of cooperation with the cone is constituted by an annular seal 26, housed in a groove 28 of the outer surface 20 of the tip. It is preferably a lip seal 26 to reduce the fitting force, this seal being located between the first group and the second group. Alternatively, the seal 26 could be arranged between the second group and the third group, without departing from the scope of the invention.

 The lip seal 26 has one or more lips, preferably one. The lip is frustoconical in shape, flaring upwardly from an annular base of the joint. The annular base and the lip are preferably made in one piece, made of EPDM elastomer material, having a Shore A hardness of 40 to 100.

 In the unconstrained state, the lip seal 26 has an outer diameter, for example of the order of 4 mm.

The first maximum outside diameter Dmax1 is smaller than the second maximum outside diameter Dmax2. Together they define, thanks to their difference in size, a first longitudinal portion of tip 6a centered on the axis 7 and having a first taper schematized by the line referenced Conl in Figure 2. Similarly, the second outer maximum diameter Dmax2 is smaller than the third outer diameter Dmax3 maximum. Together they define, thanks to their difference in size, a second longitudinal portion of tip 6b adjacent to the first portion 6a, and also centered on the axis 7. The second portion 6b has a second conicity schematized by the line referenced Con2 in Figure 2, this second taper being lower than the first.

 By way of example, the first conicity Con1 is between 3 and 4.5 °, while the second Con2 conicity is between 2 and 3.4 °.

 Thus, depending on the conicity of the flange 8a of the cone to be fitted, the latter will see its inner surface held by friction either by the first and the second group of retaining elements, or by the second and third groups of elements. detention. In all cases, the frictional retention will be well achieved using two groups spaced axially from each other, for a satisfactory mechanical maintenance and for the conservation of the centering and parallelism between the cones present on different multichannel pipette tips.

 The seal represents a function filled separately by the dedicated seal 26.

 Now with reference to Figures 4 to 5a ', it is shown different examples of cooperation between the tip 6 and cones 8 having conicities adapted to the first conicity Conl defined by the first and second retaining elements. In FIG. 4, the arrows carried on the cone show the forces to which it is subjected during scraping of its end on and then 42 of a plate 40, during a licking movement 15.

Figure 4 thus shows the contact between firstly the first elements 24-la and the frustoconical inner surface of the flange of the cone, and secondly between the second elements 24-2a and the same inner surface. In this first example, the size of the cone is such that its retention at the first group is exclusively achieved by the first two elements 24-la, since there is no contact with the other two first elements 24-lb . This example is shown on Figures 4 and 5a. In addition, because of its axisymmetric character, the second group makes contact between each of its retaining elements 24-2a and the inner surface of the collar, as shown in Figure 5b.

 In another example shown in FIG. 5a ', the cone 8 having a larger dimension is deformed by the support of the first elements 24-la during a deeper penetration of the tip 6 into the cone, this deformation exhibiting a substantially elliptical character leading to contact with the other first elements 24-lb with the inner surface of the cone.

 Referring now to FIGS. 6 to 7c, various examples of cooperation between the nozzle 6 and cones 8 having conicities adapted to the second conicity Con2 defined by the second and third retaining elements are shown.

 Figure 6 shows the contact between firstly the second elements 24-2a and the frustoconical inner surface of the flange of the cone, and secondly between the third elements 24-3a and the same inner surface. In this example, the dimension of the cone is such that its retention at the third group is exclusively achieved by the two third elements 24-3a, since there is no contact with the other two third elements 24-3b. This example is shown in Figures 6 and 7c. In addition, because of its axisymmetric character, the second group here also establishes a contact between each of its retaining elements 24-2a and the inner surface of the collar, as shown in Figure 7b.

 In another example shown in Figure 7c ', the cone 8 having a larger dimension is deformed by the support of the third elements 24-3a during a deeper penetration of the tip 6 in the cone, this deformation having a substantially elliptical character leading to contact with the other third elements 24-3b with the inner surface of the cone.

 Of course, various modifications may be made by those skilled in the art to the invention which has just been described, solely by way of non-limiting examples. In particular, the invention applies identically or similarly to an automated pipetting system tip, also called robot.

Claims

1. Tip (6) sampling cone holder for the lower part of the pipetting system, the tip having a longitudinal axis (7) fitting into a first fictitious plane (PI), characterized in that it comprises successively from bottom to top along its longitudinal axis (7), projecting radially outwards from an external surface (20) of the end piece: - a first group of first elements (24-la, 24-lb) for retaining the sampling cone spaced from each other along a first annular zone (20-1) of the tip, two of said first elements of retainer (24-la) being arranged in a second fictitious plane (P2) orthogonal to the first fictitious plane (PI), and defining an exterior diameter of largest dimension, called the first maximum exterior diameter (Dmaxl); - a second group of second sampling cone retaining elements (24-2a) spaced from each other along a second annular zone (20-2) of the tip, two of said second retaining elements being arranged in said second fictitious plane (P2) and defining an external diameter of largest dimension, called second maximum external diameter (Dmax2); - a third group of third elements (24-3a, 24-3b) for retaining the sampling cone spaced from each other along a third annular zone (20-3) of the tip, two of said third elements of retained (24-3a) being arranged in said second fictitious plane (P2) and defining an external diameter of largest dimension, called third maximum external diameter (Dmax3); in that the tip also carries a seal (26) arranged between the first and the third annular zone (20-1, 20-3) of the tip, and in that on the one hand the first maximum external diameter (Dmaxl) as well as the second maximum external diameter (Dmax2) are different so as to jointly define a first tip portion (6a) having a first conicity (Conl), and on the other hand the second maximum external diameter (Dmax2) as well as the third maximum external diameter (Dmax3) are different so as to jointly define a second tip portion (6b) having a second conicity (Con2) less than the first conicity. 2. Lower part (4) of a pipetting system comprising at least one tip (6) sampling cone holder according to any one of the preceding claims. 3. Lower part according to claim 2, intended for a single-channel pipetting system and comprising a single tip (6) carrying a sampling cone. 4. Lower part according to claim 2, intended for a multichannel pipetting system and comprising a plurality of tips (6) sampling cone holders having longitudinal axes (7) fitting into said first fictitious plane (PI). 5. Lower part according to any one of claims 2 to 4, characterized in that the first retaining elements (24-lb) of the first group, with the exception of said two first retaining elements (24-la) defining the first maximum external diameter (Dmaxl), are located radially inwards and at a distance from a first fictitious circle (Cl) defined by said first maximum external diameter (Dmaxl). 6. Lower part according to claim 5, characterized in that the first group comprises, in addition to said two first retaining elements (24-la) defining the first maximum external diameter, one or more pairs of first retaining elements (24- lb) defining one or more first diameters (Dinfl) less than the first maximum external diameter, among which at least one first lower diameter (Dinfl) located in said first fictitious plane (PI). 7. Lower part according to any one of claims 2 to 6, characterized in that the third retaining elements (24-3b) of the third group, with the exception of said two third retaining elements (24-3a) defining the third maximum external diameter (Dmax3), are located radially inwards and at a distance from a third fictitious circle (C3) defined by said third maximum external diameter (Dmax3). 8. Lower part according to claim 7, characterized in that the third group comprises, in addition to said two third retaining elements (24-3a) defining the third maximum external diameter (Dmax3), one or more pairs of third retaining elements (24-3b) defining one or more third diameters (Dinf3) less than the third maximum external diameter, among which at least one third lower diameter (Dinf3) located in said first fictitious plane (PI). 9. Lower part according to any one of claims 2 to 8, characterized in that the second retaining elements (24-2a) of the second group are located on a second fictitious circle (C2) defined by said second maximum external diameter ( Dmax2). 10. Lower part according to claim 9, characterized in that the second group comprises, in addition to said two second retaining elements (24-2a) defining the second maximum external diameter (Dmax2), one or more pairs of second retaining elements (24-2a) defining one or more other second maximum external diameters (Dmax2), among which at least one second maximum external diameter (Dmax2) located in said first fictitious plane (PI). 11. Lower part according to any one of claims 2 to 10, characterized in that the first conicity (Conl) is between 3 and 4.5°, and in that the second conicity (Con2) is between 2 and 3.4°. 12. Lower part according to any one of claims 2 to 11, characterized in that the number of ends (6) is between 2 and 16. 13. Lower part according to any one of claims 2 to 12, characterized in that the seal (26) is a lip seal. 14. Pipetting system (1) comprising a lower part (4) according to any one of claims 2 to 13, said pipetting system being a sampling pipette or an automated pipetting system. 15. Assembly comprising a pipetting system (1) according to the preceding claim, as well as at least one sampling cone (8) mounted on the tip (6) and retained thereon by friction with the first and second elements retainer, or with the second and third retainer elements.