EP3442709A1

EP3442709A1 - Pipette for withdrawing an extended range of volumes of liquid

Info

Publication number: EP3442709A1
Application number: EP17716876.2A
Authority: EP
Inventors: Bruno DUDEK; Stéphane Guichardon
Original assignee: Gilson SAS
Current assignee: Gilson SAS
Priority date: 2016-04-12
Filing date: 2017-04-11
Publication date: 2019-02-20
Anticipated expiration: 2037-04-11
Also published as: US11084030B2; CA3020272A1; US20190151839A1; JP6914961B2; FR3049877B1; ES2776714T3; CN108883416A; JP2019513550A; WO2017178448A1; FR3049877A1; KR20180129818A; PL3442709T3; EP3442709B1; CN108883416B

Abstract

In order to extend the operating range of a withdrawing pipette, the invention provides: – a fixed pipette body (22); – an operating rod (12) movable in translation relative to the pipette body (22), along a longitudinal axis (9) of the pipette; – a suction chamber (42); – a set of N concentric pistons (24a-24c), N corresponding to an integer greater than or equal to 2, each of the pistons contributing to delimiting the said suction chamber (42); and – a coupling module (50) coupling the operating rod (12) with the set of N concentric pistons (24a-24c), the said module being configured in such a way as to be able to be brought into N distinct configurations in which it respectively couples the operating rod (12) with 1, 2,…, N pistons.

Description

PIPETTE FOR THE COLLECTION OF AN EXTENDED BEACH OF LIQUID VOLUMES

DESCRIPTION

TECHNICAL FIELD The invention relates to the field of sampling pipettes, also called laboratory pipettes or liquid transfer pipettes, intended for sampling and dispensing liquid in containers or the like.

The pipettes concerned by the present invention are manual pipettes and motorized pipettes. These pipettes are intended to be held in hand by an operator, during the operations of sampling and dispensing liquid. For manual pipettes, these operations are performed by setting in motion a pipetting control button, obtained by the application of an actuating pressure on the same button which is transferred mechanically to a control rod. On motorized pipettes, the pressure of the operator on the control button generates a signal that is transmitted to the control unit of the pipette, so that it triggers the setting in motion of the control rod through of a suitable motor embedded in the pipette.

It is noted that in the manual pipettes concerned by the present invention may have an electronic meter and / or display, the pipette then having a "hybrid" character because combining both a mechanical appearance and an electronic aspect.

STATE OF THE PRIOR ART

For many years, the design of sampling pipettes has been the subject of many improvements, aimed essentially at simplifying the design of the pipettes, or to improve their ergonomics.

Usually, to obtain an acceptable accuracy, the range of volumes that can be collected by a pipette is between about 10% of the nominal volume, and 100% of this nominal volume corresponding to the maximum volume that the pipette can collect.

Therefore, when an operator has to pipette different samples spanning a wide range, these operations require the use of multiple pipettes. For example, when a series of operations requires the pipetting of volumes in the range of 3 to 1250 μΙ, the following three pipettes may be required:

- a first pipette with a nominal volume of 30 μΙ, which can be used over a range of volumes ranging from 3 to 30 μΙ;

- a second pipette with a nominal volume of 300 μΙ, which can be used over a range of volumes from 30 to 300 μΙ; and

- A third pipette with a nominal volume of 1250 μΙ, which can be used over a range of volumes from 300 to 1250 μΙ.

In this situation, the plurality of pipettes guarantees precision and accuracy, but it leads to clutter the bench.

STATEMENT OF THE INVENTION

The object of the invention is therefore to at least partially respond to the disadvantage identified above.

To do this, the subject of the invention is a sampling pipette comprising:

- pipette body;

a control rod displaceable in translation relative to the pipette body, along a longitudinal axis of the pipette; and

- a suction chamber.

According to the invention, the pipette also comprises:

a set of N concentric pistons, N corresponding to an integer greater than or equal to two, each of the pistons participating in the delimitation of said suction chamber; and a module for coupling the control rod with the set of N concentric pistons, said module being configured so that it can be fed into N distinct configurations in which it respectively mates the control rod with 1, 2, ..., N pistons.

The invention is thus remarkable in that it makes it possible to extend the range of volumes that can be sampled by implanting several pistons within the pipette as well as a module for coupling the control rod with each of these pistons. . Therefore, during a pipetting operation, the number of pistons in operation is a function of the volume to be sampled.

This solution has the advantage of reducing the number of pipettes required when the pipetting operations require the sampling of various volumes, without affecting the accuracy and accuracy performance of the pipette. This advantageously results in a saving of space on the bench. In addition, by replacing several pipettes with a single pipette, this offers a possibility of traceability of a protocol by recording all the pipetings made with the same pipette.

In addition, the pipette according to the invention has a small footprint, thanks to the concentric arrangement of its pistons.

The invention furthermore exhibits at least one of the following optional features, singly or in combination.

It is provided :

that the coupling module comprises at least one piston attachment finger extending radially relative to the longitudinal axis of the pipette,

that at least N-1 pistons each have a circumferentially oriented and open hooking slot, the slots having different circumferential lengths for each of said at least N-1 pistons,

and that said pipette is configured so that the gripping finger can be moved circumferentially in and out of the radially opposite slots of each other. In other words, the coupling / uncoupling of each piston with the control rod is effected by a connection of the bayonet type, with the finger constituting the lug of this connection. Thanks to the inventive design that has been developed, the number of pistons coupled to the control rod simply depends on the relative angular position between the finger and the slots located radially opposite each other. This angular relative position can be obtained manually by the operator by means of a suitable control member positioned on the pipette, or more preferably, automatically by means of motorized means controlled by a control unit of the pipette. .

Nevertheless, the coupling module can take any other form deemed appropriate, without departing from the scope of the invention. For example, this module can be based on a mechanical grip, magnetic, etc.

The coupling module comprises a rotary coupling member equipped at its lower end with said finger, and rotatably mounted at its upper end on the control rod, along the longitudinal axis of the pipette.

The rotary coupling member is preferably made with two pieces mounted sliding relative to one another, along the longitudinal axis of the pipette, a deployment spring being arranged between these two parts so that to generate an effort to separate them from each other.

The coupling module comprises a control rod extension integral in translation with the control rod, and said two parts of the rotary coupling member are respectively formed by an upper part and a lower part, the latter being mounted movably. in translation along the longitudinal axis, relative to the control rod extension.

The coupling module further comprises a movement transformation body cooperating with the rotary coupling member so that a relative movement of translation between them two along the longitudinal axis simultaneously leads to a relative rotation between them. , also along the longitudinal axis. In other words, the cooperation between the motion transformation body and the rotary coupling member causes a helical movement of the latter. Preferably, the motion transformation body comprises at least a first helical ramp and at least one second helical ramp, and the rotary coupling member is equipped with a follower roller which, when it co-operates with the first ramp makes it possible to cause rotation of the rotary coupling member in a first direction of rotation, and which, when it cooperates with the second ramp, makes it possible to cause rotation of the rotary coupling member in a second direction of rotation. rotation. This design allows the coupling and uncoupling of the pistons in a simple and reliable way.

The sampling pipette is preferably designed so that the rotation of the rotary coupling member according to the first direction of rotation is obtained by a first overtravel downwards of the control rod from an end-of-travel position. purge thereof, and the rotation of the rotary coupling member in the second direction of rotation is achieved by a second upward stroke of the control rod from a high pipetting position of this rod. control. Thus, the pipette is designed to obtain the coupling and uncoupling of the pistons by simple translations of the control rod, in overcurrents respectively going beyond the purge stroke and set back relative to the high pipetting position. One of the advantages of this specificity lies in the design simplicity of the pipette, since it is the same control rod, in a movement with the same degree of freedom of translation, which alternatively allows the pipetting operations and the operations of coupling and uncoupling pistons.

Preferably, the first overtravel occurs against a force generated by a first centering spring tending to push the coupling member upwards relative to the movement transformation body, and the second overtravel occurs against a force generated by a second centering spring tending to push the coupling member downwardly relative to the motion transformation body.

Preferably, the pipette is configured so that the displacement of the control rod is carried out manually or motorized, as indicated previously. In this regard, it is noted that hybrid pipettes also fall within the scope of the invention.

Preferably, the number N of pistons is greater than or equal to three, but a solution with two concentric pistons is also possible, without departing from the scope of the invention.

The sampling pipette is preferably designed so that it can take a volume range from 0.5 to 1250 μΙ, or designed so as to take a range of volumes from 500 to 10,000 μΙ.

The innermost piston is permanently attached to the coupling module. Alternatively, it could also be coupled and uncoupled to the control rod, via the coupling module. According to yet another alternative, it is the outermost piston that could be permanently secured to the coupling module.

The pipette comprises a control device for adjusting the volume to be sampled, such as a knob, knob, or other conventional form.

Finally, it is noted that the sampling pipette may be a single-channel or multichannel pipette.

Other advantages and features of the invention will become apparent from 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 motorized sampling pipette according to a preferred embodiment of the present invention;

- Figure 2 is an axial sectional view of a lower part of the pipette shown in the previous figure;

- Figure 3 is a perspective view of a piston coupling module implemented in the pipette shown in the preceding figures;

- Figure 4 is in axial section of the previous figure; - Figure 5 is in sectional view taken along the line VV of the previous figure;

- Figure 6 is a perspective view of a lower part of the coupling module shown in Figures 3 and 4, cooperating with the pistons of the pipette;

FIGS. 7a to 7c show schematic pipetting operations with the coupling module in first configuration;

FIGS. 8a to 8c show schematic pipetting operations with the coupling module in second configuration;

FIGS. 9a to 9c schematize pipetting operations with the coupling module in third configuration;

FIGS. 10a to 11b schematize the passage from the first to the second configuration of the coupling module;

- Figures 12 to 13b schematically the passage of the second to the third configuration of the coupling module;

FIGS. 14a to 15b schematize the passage from the third to the second configuration of the coupling module; and

- Figures 16a to 17b schematically the passage from the second to the first configuration of the coupling module.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring firstly to FIGS. 1 to 5, there is shown a motorized sampling pipette 1 according to a preferred embodiment of the invention.

Conventionally, this motorized pipette 1 is intended to be held by the hand of an operator, who, with the help of his thumb, is able to actuate a control button of the pipette to generate the dispensation of a liquid that has been previously aspirated.

Specifically, the single channel pipette 1 comprises a handle 6 forming the upper body of the pipette, and above which is the pipetting control button 3, the upper part is intended to undergo the pressure of the thumb of the operator . As an indication, it is noted that an electronic display screen 4 is provided on the handle 6, as well as control members 8 such as knobs or wheels, and in particular a volume control control member to be taken.

The upper part of the pipette is also equipped with an electronic control unit 10 and a motor 11, the latter preferably being DC and controlled by the unit 10.

The output shaft 13 of the motor 11 is mechanically coupled to a device 15 for translating a control rod 12 of the pipette, along a pipette longitudinal axis 9 also corresponding to the longitudinal direction thereof. It is noted that most of the constituent elements of the pipette are of revolutionary forms, and centered on this axis 9.

Under the handle 6, the pipette 1 comprises a removable lower part 14, which ends downwards by a cone holder 16 receiving a consumable 18, also called sampling cone.

A cone ejector 20 opens down from the handle 6. Conventionally, the ejector 20 can be moved relative to the handle 6 and the lower portion 14, both forming a fixed body 22 of the pipette.

One of the peculiarities of the invention lies in the fact that the pipette is equipped with several concentric pistons, here three pistons referenced 24a, 24b, 24c. The number N of pistons could nevertheless be greater or less than 3, without departing from the scope of the invention.

The three pistons are housed in the lower part 14, and centered on the longitudinal axis 9. The first piston 24a, located inside, has a cylindrical section of circular shape. The second piston 24b has an annular cross section, surrounding the first piston 24. The upper end 24b 'of the second piston 24b defines an axial housing 26 open upwards, and whose bottom is equipped with an O-ring 28 traversed by the first piston 24a. However, in the current portion of the second piston 24b, a small radial clearance is provided between the two pistons 24a, 24b, so that the air can enter. It is indicated that throughout the description, the terms "high" and "low" are to be considered in relation to the pipette held in the hand of the operator, with a orientation such as that adopted during pipetting operations, that is to say with the control button 3 facing upwards.

In a similar manner to that described above, the upper end 24c 'of the third piston 24c defines an axial housing 30 open upwards, and whose bottom is equipped with an O-ring 32 traversed by the second piston 24b. However, in the current portion of the third piston 24c, a small radial clearance is provided between the two pistons 24b, 24c, so that the air can enter.

The third piston 24c has a low end equipped with a lip seal 40 conforming to the inner surface of the fixed body 22.

Each of the second and third pistons 24b, 24c has lugs 34 extending radially outward and slidably mounted in vertical inner grooves 36 of the fixed body 22, as can be seen in FIG. 4. This makes it possible to block the rotation pistons relative to the fixed body 22 of the pipette.

The pistons participate with their lower ends in the delimitation of a single suction chamber 42, the lower part of which communicates with a channel 44 through which the cone holder 16 passes.

As an indicative example, the pipette is intended to allow the removal of liquid in a volume range from 0.5 to 1250 μΙ, or in a volume range from 500 to 10,000 μΙ. In the first case, it is for example provided a first piston 24a whose intrinsic sampling capacity is of the order of 50 μΙ, and a second piston 24b which, when associated with the first piston 24a, together have a capacity intrinsic sampling of the order of 350 μΙ, and finally a third piston 24c which, when associated with the first and second pistons 24a, 24b, has an intrinsic sampling capacity is of the order 1250 μΙ.

Depending on the desired volume, set by the operator via the dedicated control member on the pipette, the control control unit 10 is capable of ordering operation:

first piston 24a only;

first and second pistons 24a, 24b;

first, second and third pistons 24a-24c. To do this, the pipette 1 is equipped with a coupling module 50 specific to the invention, for coupling and uncoupling each of the pistons with the control rod 12. More specifically, the module 50 is configured so it can be brought into three distinct configurations in which it mates the control rod 12 with the first piston 24a only, the first and second pistons 24a, 24b, and finally the first, second and third pistons 24a-24c .

More specifically with reference to FIGS. 3 and 4, the coupling module 50 will be described in detail.

First, the module 50 has a control rod extension 52 integral in translation with the control rod 12, and extending downwardly from the same rod. Preferably, the extension 52 is mounted screwed at its upper end to the lower end of the control rod 12.

The lower end of the extension 52, centered on the axis 9, fixedly and permanently carries the first piston 24a, a screwed connection, glued or otherwise, being for example provided between their respective ends.

In addition, the module 50 comprises a rotary coupling member 56, arranged around the control rod extension 52. Preferably, this member 56 is made with two pieces mounted sliding relative to each other. the other, along the axis 9. It is firstly a high piece 56a fixed in translation relative to the rod 12 and its extension 52, but rotatable relative to them, according to the axis 9. It is then a low part 56b rotatably coupled to the upper part 56a, for example by means of a key 60.

A deployment spring 62 is arranged between the two parts 56a, 56b, so as to generate a force tending to separate them from one another. This deployment spring 62 bears against an inner bearing surface of the lower part 56b, and a coupling ring of the upper ends of the upper part 56a and the extension 52.

The lower part 56b is thus mounted to move in translation along the axis 9, relative to the extension 52 and to the control rod 12. It is also equipped with its lower end, at least one piston attachment finger 64, preferably two diametrically opposite fingers as shown in Figure 3.

Each gripping finger 64 extends radially outwardly from the lower part 56b. As will be described below, the angular position of these fingers 64 conditions the number of pistons coupled to the module 50.

To vary the angular position of the fingers 64, the coupling module 50 further comprises a movement transformation body 66, intended to transform a translation movement into a rotational movement along the same axis 9. In fact, this body 66 cooperates with the upper part 56a of the rotary coupling member 56 so that a relative translational movement between them two along the axis 9, leads simultaneously to a relative rotation between them two along the same axis. It is therefore necessary to obtain a helical movement of the rotary coupling member 56, which is made possible by means of ramps provided on the body 66 as well as follower rollers carried by the rotary member 56.

More specifically, the member 56 is equipped with two follower rollers 68 arranged diametrically opposite, and rotatably mounted along the same transverse axis 76 orthogonal to the axis 9. With each follower 68, there is associated a first helical ramp 70a located inside the body 66, and a second helical ramp 70b also located inside the body 66, facing the first ramp. The design is such that when each follower roller 68 cooperates with its associated first ramp 70a, it makes it possible to cause rotation of the rotary member 56 in a first direction of rotation 72a about the axis 9. Conversely, when it cooperates with its associated second ramp 70b, it allows to cause the rotation of the rotary member 56 in a second direction of rotation 72b opposite to the first direction.

It is furthermore noted that each follower 68 is carried by a counter

74 of rotation support centered on the axis 76, this pin opening into a radial opening 78 of the motion transformation body 66.

The axial positioning of the rotational coupling member 56 relative to the body 66 is provided by two compression springs, namely a first centering spring 80a tending to push the member 56 upwards relative to the body 66, and a second centering spring 80b tending to push the coupling member downwardly relative to the motion transformation body 66.

To do this, the first spring 80a is housed inside the body 66 between a low end thereof and a shoulder 82 located at the upper end of the rotary member 66, while the second spring 80b is housed inside the body 66 between an upper end of the latter and the same shoulder 82. It is noted moreover that it is on this shoulder that are preferably mounted the follower rollers 68, via the pins 74.

Referring now to Figure 6, in combination with Figures 3 and 4, it will now be described the cooperation between the coupling module 50 and the first and second pistons 24b, 24c, it being understood that the first piston 24a remains permanently attached to this coupling module 50.

At its upper end 24b ', the second piston 24b has two hook slots 84b diametrically opposite (only one being visible in Figure 6). Each slot 84b is circumferentially oriented, open in the same direction at one of its ends, and has a slot bottom at the opposite end. These slots 84b, intended to cooperate with the fingers 64 in the form of lugs, are thus defined by notches 86b similar to those of a bayonet connection.

Similarly, at its upper end 24c ', the third piston 24c has two hook slots 84c diametrically opposed (only one being visible in Figure 6). Each slot 84c is also circumferentially oriented, open in the same direction at one of its ends, and has a slot bottom at the opposite end. These slots 84c, also intended to cooperate with the fingers 64 in the form of lugs, are defined by notches 86c also comparable to those of a bayonet connection.

Slots 84b, 84c are grouped by pairs. For the same pair of slots 84b, 84c as shown in Figure 6, they are located radially opposite each other. They are in other words considered superimposed in the radial direction, overlapping only partially in the circumferential direction. Indeed, the two slots 84b, 84c of the same couple have different circumferential lengths while having their slit bottoms aligned in the radial direction. Therefore, in the preferred embodiment which is described and shown in the figures, this implies that each notch 86b provided on the second piston 24b and delimiting the slot 84b, is longer than the notch 86c provided on the third piston 24c and defining the slot 84c.

The width of the slots 84b, 84c is preferably identical, and provided so that the gripping fingers 64 can be moved circumferentially in and out of these slots. Preferably, the slit width is slightly greater than the diameter of the fingers.

With this configuration, the number of pistons coupled to the lower part 56b of the module 50 thus depends on the relative angular position between each finger 64 and its pair of associated slots 84b, 84c. Figure 6 schematizes this principle well, since in a first configuration of the module 50 shown with the finger 64 in solid line, the same finger 64 adopts an angular position such that it is outside the two slots 84b, 84c. In this first configuration, the two pistons 24b, 24c are not coupled, only the first piston remaining integral with the module 50. This first configuration is for example adopted by the control unit for pipetting volumes falling within a range. ranging from 0.5 to 30 μΙ.

In a second configuration of the module 50, shown with the dotted finger 64 in the middle of Figure 6, each finger 64 adopts an angular position such that it is in the slot 84b, but outside the slot 84c. The cooperation between the finger 64 and the notch 86b is similar to a bayonet connection. For example, an angular offset of 20 to 25 ° is provided between the position of the finger 64 of the first configuration, and that of the second configuration. In it, the two pistons 24a, 24b are thus coupled to the module 50, but not the third piston 24c. This second configuration is for example adopted by the control unit for pipetting volumes in a range from 30 to 300 μΙ.

In a third configuration of the module 50, shown with the dotted finger 64 on the right of FIG. 6, the finger 64 adopts an angular position such that it is located in the slots 84b, 84c, close to or in contact with the slot bottoms. The cooperation between the finger 64 and the notches 86b, 86c is similar to bayonet links. For example, an angular offset of 20 to 25 ° is provided between the position of the finger 64 of the second configuration, and that of the third configuration. In this, the three pistons 24a-24c are thus coupled to the module 50. This second configuration is for example adopted by the control unit for pipetting volumes in a range from 300 to 1250 μΙ.

Referring now to FIGS. 7a to 7c, the operation of the pipette 1 will be described when its coupling module 50 is in the first configuration, namely with only its first inner piston 24a coupled to this module.

FIG. 7a shows the pipette 1 with its control rod in the high pipetting position, for example at the end of the suction stroke. The piston 24a coupled to the module 50 is thus in its highest position relative to the fixed body 22 of the pipette. As for the other two pistons 24b, 24c, they are in an inactive position in low abutment against the fixed body 22. At this stage, the follower rollers 68 are substantially centered with respect to the motion transformation body 66, also in the high position.

The dispensing of the aspirated liquid is then controlled by the control knob, which induces the actuation of the motor driving the control rod 12 to move downwards. During this dispensing stroke, the movement of the rod 12 downwards causes the module 50 which also slides along the fixed body 22. The pistons 24b, 24c remain stationary, unlike the first piston 24a descending. The state of the pipette at the end of the dispensing stroke is shown in FIG. 7b, while the further descent of the rod 12 leads to the completion of a purge stroke, the final state of which is represented on FIG. Figure 7c.

Referring now to FIGS. 8a to 8c, the operation of the pipette 1 will be described when its coupling module 50 is in the second configuration, namely with only its first and second pistons 24a, 24b coupled to this module. . FIG. 8a shows the pipette 1 with its control rod in the high pipetting position, for example at the end of the suction stroke. The pistons 24a, 24b coupled to the module 50 are in their highest position relative to the fixed body 22 of the pipette. During pipetting, the axial relative position of these two pistons remains unchanged. As for the third piston 24c, it remains in an inactive position in low abutment against the fixed body 22. At this stage, the follower rollers 68 are substantially centered with respect to the motion transformation body 66, also in the high position.

The dispensing of the aspirated liquid is then controlled by the control knob, which induces the actuation of the motor driving the control rod 12 to move downwards. During this dispensing stroke, the movement of the rod 12 downwards causes the module 50 which also slides along the fixed body 22. The piston 24c remains stationary, unlike the pistons 24a, 24b which descend simultaneously. The state of the pipette at the end of the dispensing stroke is shown in FIG. 8b, while the continued descent of the rod 12 leads to the completion of a purge stroke, the final state of which is represented on FIG. Figure 8c.

Referring now to Figures 9a to 9c, the operation of the pipette 1 will be described when its coupling module 50 is in the third configuration, namely with all its pistons 24a-24c, coupled to this module.

FIG. 9a shows the pipette 1 with its control rod in the high pipetting position, for example at the end of the suction stroke. The pistons 24a-24c coupled to the module 50 are in their highest position relative to the fixed body 22 of the pipette. During pipetting, the axial relative position of these three pistons remains unchanged. At this stage, the follower rollers 68 are substantially centered with respect to the motion transformation body 66, also in the high position. All as in the other two configurations, the position of the rollers 68 within the module is not brought to evolve during pipetting.

The dispensing of the aspirated liquid is then controlled by the control knob, which induces the actuation of the motor driving the control rod 12 to move downwards. During this dispensing race, the movement of the rod 12 towards the low causes the module 50 which also slides along the fixed body 22. The three pistons 24a-24c then descend simultaneously, pushed by the rod 12 and the module 50. The state of the pipette end of dispensing stroke is shown in Figure 9b, while the continued descent of the rod 12 leads to the realization of a purge stroke, the final state is shown in Figure 9c.

FIGS. 10a to 10c and FIGS. 11a and 11b schematize an operation to move from the first configuration to the second configuration of the module 50. To do this, a first overtravel is ordered by the control unit, downwards from the purge end position as shown in Figure 7c.

The body 66 firstly abuts on the fixed body 22. As the first overtravel continues, the upper part 56a of the rotary member 56 is rotated due to the support of the follower rollers 68 on their ramps 70a. This helical movement is transmitted to the lower part 56b, and its gripping fingers 64. It is performed against the return force generated by the first centering spring 80a, compressing the latter. During this movement, the fingers 64 of the lower part 56b then come into axial abutment against the upper ends 24b ', 24c' of the pistons 24b, 24c, this state corresponding to that shown in Figures 10a and 11a. Then, the first overtravel continues and the upper part 56a continues to be driven helically, while the lower part 56b undergoes only a rotation along the axis 9 in the first direction 72a, due to its locking in translation. The relative movement of translation between the two parts 56a, 56b is made against the return force generated by the deployment spring 62, compressing the latter.

During this rotation whose angular extent is perfectly controlled because it depends directly on the extent of the axial overtravel of the control rod 12, the gripping fingers 64 penetrate the slots 84b. However, this angular displacement of the fingers 64, for example of the order of 22.5 °, is not sufficient for them to enter the slot 84c. The insertion of the fingers 64 into the slots 84b causes coupling of the second piston 24b with the module 50. This mechanical coupling state is shown in Figures 10b and 11b.

Once the coupling has been made, the control unit of the pipette orders the rod 12 to be raised to the end of purge position, which has the consequence of simultaneously raising the first and second pistons 24a, 24b, as this is shown in Figure 10c. The third piston 24c remains in its fixed position.

Then, pipetting operations can be ordered in a conventional manner, for volumes corresponding to the range associated with the set of two pistons 24a, 24b.

FIGS. 12 to 12c and FIGS. 13a and 13b schematize an operation for moving from the second configuration to the third configuration of the module 50. To do this, another first overtravel of greater amplitude than the previous one is ordered by the unit. control, down from the purge end position as shown in FIG.

The body 66 firstly abuts on the fixed body 22. As the first overtravel continues, the upper part 56a of the rotary member 56 is rotated due to the support of the follower rollers 68 on their ramps 70a. This helical movement is transmitted to the lower part 56b, as well as to its gripping fingers 64. During this movement, the fingers 64 of the lower part 56b then come into axial abutment against the upper end 24c 'of the piston 24c, this state corresponding to that shown in Figures 12a and 13a.

Then, the first overtravel continues and the upper part 56a continues to be helically driven downwards, while the lower part 56b undergoes only a rotation along the axis 9 in the first direction 72a, because of its locking in. translation. During this rotation whose angular extent is perfectly controlled because it depends directly on the extent of the axial overtravel of the control rod 12, the gripping fingers 64 penetrate the slot 84c. This angular displacement of the fingers 64 is for example of the order of 22.5 °, and sufficient to come against or near the bottom of the slots 84b, 84c. The insertion of the fingers 64 in the slots 84c causes the coupling of the third piston 24b with the module 50. This state of mechanical coupling is shown in Figures 12b and 13b.

Once the coupling is achieved, the control unit of the pipette orders the rod 12 to be raised to the end of purge position, which has the consequence of simultaneously raising the three pistons 24a-24c, as shown in Figure 12c. Then, pipetting operations can be ordered in a conventional manner, for volumes corresponding to the range associated with all three pistons 24a-24c.

Of course, it is noted that a direct passage from the first to the third configuration can be ordered by the control unit of the pipette, adapting accordingly the amplitude of the first race downwards.

FIGS. 14a to 14d and FIGS. 15a and 15b schematize an operation for moving from the third configuration to the second configuration of the module 50. To do this, a second overtravel is ordered by the control unit, upwards from a high pipetting position as shown in Figure 14a.

In this state of sampling of nominal volume associated with the third configuration, the body 66 is in high abutment on the fixed body 22. As the second overtravel continues upwards, the upper part 56a of the body rotary 56 is rotated due to the support of the follower rollers 68 on their ramps 70b, as shown schematically in FIG. 15a. This helical movement is transmitted to the lower part 56b, and its gripping fingers 64. It is performed against the return force generated by the second centering spring 80b, compressing the latter. During this movement during which the two pistons 24b, 24c slide while remaining fixed in rotation, the fingers 64 in helical movement progressively escape from the slot 84c. At the end of the second overtravel, the fingers 64 are fully extended from the slots 84c, so that the third piston 24c is uncoupled from the module 50. This state is shown in Figures 14b and 15b.

Then, the control unit of the pipette orders a downward movement of the control rod 12, so that the fingers 64 push the third piston 24c into its lower position, abutting against the fixed body 22. This phase is represented in FIG. 14c. It precedes the final phase of raising of the module 50 and the two pistons 24a, 24b, thanks to an axial displacement upwardly of the control rod 12 as shown diagrammatically in FIG. 14d.

FIGS. 16a and 16b as well as FIGS. 17a and 17b schematize an operation aiming to pass from the second configuration to the first configuration of the module 50. To do this, another second overtravel of greater amplitude than the previous one is ordered by the control unit, upward from a high pipetting position as shown in Figure 16a.

In this state of sampling of nominal volume associated with the second configuration, the body 66 is in high abutment on the fixed body 22. As the second overtravel continues upwards, the upper part 56a of the body rotary 56 is rotated due to the support of the follower rollers 68 on their ramps 70b, as shown schematically in Figure 17a. This helical movement is transmitted to the lower part 56b, and to its gripping fingers 64. During this movement during which the piston 24b slides while remaining fixed in rotation, the fingers 64 in helical movement progressively escape slots 84b. At the end of the second overtravel, the fingers 64 are fully extended from the slots 84b, so that the second piston 24b is uncoupled from the module 50. This state is shown in Figures 16b and 17b.

Then, the control unit of the pipette orders a downward movement of the control rod 12, so that the fingers 64 push the second piston 24b into its lower position, abutting against the fixed body 22 or against the third piston 24c already in the low stop position. This phase, similar to that shown in FIG. 14c, precedes the final phase of raising of the module 50 and the single piston 24a, thanks to an axial displacement upwards of the control rod 12.

Then, pipetting operations can be ordered in a conventional manner, for volumes corresponding to the range associated with the single first piston 24a. Here too, it is noted that a direct passage from the third to the first configuration can be ordered by the pipette control unit, correspondingly adjusting the amplitude of the second upward stroke.

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.

Claims

Sampling pipette (1) comprising:

- Fixed body (22) pipette;

- a control rod (12) displaceable in translation relative to the pipette body (22), along a longitudinal axis (9) of the pipette; and

- a suction chamber (42);

characterized in that it also comprises:

a set of N concentric pistons (24a-24c), N corresponding to an integer greater than or equal to two, each of the pistons participating in the delimitation of said suction chamber (42); and

a module (50) for coupling the control rod (12) with the set of N concentric pistons (24a-24c), said module being configured so that it can be brought into N distinct configurations in which it respectively provides the coupling of the control rod (12) with 1, 2, ..., N pistons.

2. sampling pipette according to claim 1, characterized in that the coupling module (50) comprises at least one piston attachment finger (64) extending radially relatively to the longitudinal axis (9) of the pipette ,

in that at least Nl pistons (24b, 24c) each have a circumferentially oriented and circumferentially open hooking slot (84b, 84c), the slots having different circumferential lengths for each of said at least Nl pistons, and in that said pipette is configured so that the hooking finger (64) can be moved circumferentially in and out of the slots (84b, 84c) radially facing each other.

3. A sampling pipette according to claim 2, characterized in that the coupling module (50) comprises a rotary coupling member (56) equipped at its lower end with said finger (64), and rotatably mounted at its upper end on the control rod (12), along the longitudinal axis (9) of the pipette.

4. sampling pipette according to claim 3, characterized in that the rotary coupling member (56) is produced by means of two parts (56a, 56b) mounted sliding relative to one another, along the longitudinal axis (9) of the pipette, a deployment spring (62) being arranged between these two parts (56a, 56b) so as to generate a force tending to separate them from each other.

5. sampling pipette according to claim 4, characterized in that the coupling module (50) comprises a control rod extension (52) integral in translation with the control rod (12), and in that said two parts of the rotary coupling member are respectively formed by an upper part (56a) and a lower part (56b), the latter being mounted movable in translation along the longitudinal axis (9), relative to the rod extension control (52).

The sampling pipette according to any one of claims 3 to 5, characterized in that the coupling module (50) further comprises a movement transformation body (66) cooperating with the rotary coupling member ( 56) so that a relative displacement of translation between them two along the longitudinal axis (9), leads simultaneously to a relative rotation between them, also along the longitudinal axis (9).

The sampling pipette according to claim 6, characterized in that the motion transformation body (66) comprises at least a first helical ramp (70a) and at least one second helical ramp (70b), and in that the rotary coupling member (56) is equipped with a follower roller (68) which, when it co-operates with the first ramp (70a), makes it possible to cause rotation of the rotary coupling member (56) according to a first direction of rotation (72a), and which, when it cooperates with the second ramp (70b) makes it possible to cause rotation of the rotary coupling member (56) in a second direction of rotation (72b).

8. sampling pipette according to claim 7, characterized in that it is designed so that the rotation of the rotary coupling member (56) in the first direction of rotation (72a) is obtained by a first overtravel to the bottom of the control rod (12) from a purge end position thereof, and in that the rotation of the rotary coupling member (56) in the second direction of rotation (72b) is obtained by a second upward stroke of the control rod (12) from a high pipetting position of this control rod.

9. sampling pipette according to claim 8, characterized in that the first overtravel occurs against a force generated by a first centering spring (80a) tending to push the rotary coupling member (56) towards the top relative to the motion transformation body (66), and in that the second overtravel is effected against a force generated by a second centering spring (80b) tending to urge the rotary coupling member ( 56) downwardly relative to the motion transformation body (66).

10. sampling pipette according to any one of the preceding claims, characterized in that it is a pipette configured so that the displacement of the control rod (12) is effected manually or motorized manner.

11. sampling pipette according to any one of the preceding claims, characterized in that the number N of pistons (24a-24c) is greater than or equal to three.

12. sampling pipette according to any one of the preceding claims, characterized in that it is designed so as to be able to take a volume range from 0.5 to 1250 μΙ, or designed to take a volume range of 500 to 10,000 μΙ.

13. sampling pipette according to any one of the preceding claims, characterized in that it comprises a volume control control member to be sampled (8).

14. sampling pipette according to any one of the preceding claims, characterized in that the piston (24a) the innermost is permanently secured to the coupling module (50).

15. sampling pipette according to any one of the preceding claims, characterized in that it is a pipette single channel or multichannel.