Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N1/00—Sampling; Preparing specimens for investigation
  • G01N1/02—Devices for withdrawing samples
  • G01N1/10—Devices for withdrawing samples in the liquid or fluent state
  • G01N1/14—Suction devices, e.g. pumps; Ejector devices
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
  • B01L3/00—Containers or dishes for laboratory use, e.g. laboratory glassware; Droppers
  • B01L3/02—Burettes; Pipettes
  • B01L3/021—Pipettes, i.e. with only one conduit for withdrawing and redistributing liquids
  • B01L3/0217—Pipettes, i.e. with only one conduit for withdrawing and redistributing liquids of the plunger pump type
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
  • B01L3/00—Containers or dishes for laboratory use, e.g. laboratory glassware; Droppers
  • B01L3/02—Burettes; Pipettes
  • B01L3/021—Pipettes, i.e. with only one conduit for withdrawing and redistributing liquids
  • B01L3/0217—Pipettes, i.e. with only one conduit for withdrawing and redistributing liquids of the plunger pump type
  • B01L3/022—Capillary pipettes, i.e. having very small bore
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
  • B01L3/00—Containers or dishes for laboratory use, e.g. laboratory glassware; Droppers
  • B01L3/02—Burettes; Pipettes
  • B01L3/0275—Interchangeable or disposable dispensing tips
  • B01L3/0279—Interchangeable or disposable dispensing tips co-operating with positive ejection means
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
  • B01L2200/00—Solutions for specific problems relating to chemical or physical laboratory apparatus
  • B01L2200/02—Adapting objects or devices to another

Definitions

• the present invention relates to the field of positive displacement sampling pipettes.
• Such pipettes are intended to cooperate with consumables of the capillary-piston type, whose piston is intended to be directly in contact with the sample to be taken, before being ejected or reused.
• Positive-displacement pipettes therefore have a different design from that of more conventional air-displacement pipettes, in which the piston is an integral part of the pipette.
• the invention relates more specifically to the ejection function of the capillary-piston assembly.
• Positive displacement pipettes are usually used for sampling viscous, volatile liquids and / or contaminants. Their combination with "capillary-piston" type consumables makes it possible to avoid contamination of the pipette.
• Such a pipette is for example known from FR 2 446 672.
• a control rod whose low end controls the movement of a gripping device from the upper end of a piston, flush with a capillary assembly. piston for cooperating with the pipette.
• This gripping device is also called "gripper”.
• the pipette is designed to be able to exercise two successive downward strokes with the control rod, via a control button arranged at its high end.
• the first stroke of the control rod corresponds to the dispensing stroke of the sampled sample. It is performed by opposing the restoring force of a first spring, preferably compression.
• the second stroke of the control rod corresponds to the presentation and opening of the piston gripper. It is performed by opposing the restoring force of a second spring, preferably compression, arranged in the same direction as the first spring and having a significantly higher stiffness.
• this second race has the effect of extracting the jaws of the clamp from a sheath that encloses them. Once the jaws released from their sheath, they can easily let the upper end of the piston during the installation of the consumable on the pipette, which also simultaneously sees the fitting of the capillary on the tip of the pipette.
• the first phase of raising of the control rod under the effect of the restoring force of the second spring, has the effect of retracting the jaws in the sheath of the clamp, with the upper end of the piston held by the jaws in the tight position.
• the second phase of raising of the control rod under the effect of the restoring force of the first spring of lower stiffness, leads to the displacement of this rod as well as the gripper enclosing the piston to a high position, relative to the pipette body.
• the consumable When the piston reaches its low point at the end of the first run, the consumable is plunged in the liquid to be taken. To ensure the sampling, the operator then gradually releases the pressure exerted by his thumb on the control button, which allows the control rod and the piston to go up under the effect of the restoring force of the first spring. During this ascent, the liquid in contact with the lower end of the piston is introduced into the capillary.
• the operator For dispensing, the operator carries out the first stroke of the control rod by pressing his thumb on the control button, placing the capillary in the receptacle for receiving the liquid.
• the operator may be accidentally ejected with the capillary, thus generating again a risk of accidental projection of liquid.
• the operator can perform the second stroke of the control rod to cause the desired ejection of the capillary-piston consumable. Nevertheless, this ejection operation is effected with the aid of the operator's only thumb by counteracting the restoring force of the second spring, which is necessarily substantial in order to contrast with the restoring force of the first spring, and thus to be able to perform its function of delivering a sensory signal to the operator at the end of the first race.
• the high stiffness of the second spring thus makes the pipette perfectible from an ergonomic point of view, especially since this disadvantage also occurs when the operation described above opening the clamp, before the introduction of the piston.
• the object of the invention is therefore to remedy at least partially the disadvantages mentioned above, relating to the embodiments of the prior art.
• the subject of the invention is a positive displacement sampling pipette, comprising a control rod whose low end controls the displacement of a gripping device from the upper end of an apartment piston to a set.
• capillary-piston for cooperating with said pipette the latter also comprising an ejection rod of said capillary-piston assembly, mounted movable relative to said control rod so that its lower end can exert an ejection force on the upper end of said piston housed in said gripping device, during a relative movement between the ejector rod and the control rod.
• the invention is remarkable in that it is based on a design dissociating the elements to ensure the control function of the pipette and the ejection function of the capillary-piston consumable.
• the invention provides that the ejection of the consumable is effected by a dedicated rod, separate from the control rod. Therefore, contrary to the achievements of the prior art, the risks of accidental ejection of the consumable by the control rod are advantageously reduced to nothing. Thus, during the manipulation of the pipette according to the invention, the operator can actuate the control rod without worrying about the risks of such a loss, which overall makes it possible to improve the ergonomics, the reproducibility of the samples, and the productivity.
• the ejection technology employed which relies on the thrust of the piston using the lower end of the ejector rod, itself causing in its stroke the capillary, by stop.
• the force to be delivered to ensure the ejection of the consumable can thus be much lower than that previously required to counter the restoring force of the spring with high stiffness, since it is no longer necessary to provide a high differential of spring stiffness. for the purpose of producing a sensory signal for the operator.
• the low support force required to disengage the plunger from the gripper and to dislodge the capillary from the pipette tip has no effect on the risk of accidental loss of the capillary-piston consumable, as has been the case. explained above.
• said gripping device takes the form of a gripper with at least two jaws urged in the tightened position by elastic return means, preferably surrounding these same jaws.
• elastic return means preferably surrounding these same jaws.
• step (a) the fitting of the capillary and the introduction of the piston is preferably carried out successively.
• the pressing operation is carried out in a manner similar to that performed with conventional pipettes with air displacement, without actuating the control rod.
• the introduction of the piston into the clamp is then initiated and performed by simply moving the control rod, thanks to an action requiring only a small effort on the part of the operator, essentially conditioned by the stiffness of the elastic return means surrounding the jaws.
• the above operations are therefore familiar to the operators, which enhances the ergonomics of the pipette and provides gains in terms of productivity.
• step (a) the fitting of the capillary and the introduction of the piston can be carried out simultaneously, without departing from the scope of the invention.
• step (a) the piston is in the lower abutment position in the capillary.
• said control rod is kept in the low position at the end of step (a) until the sample is taken, during which the control rod rises with the piston to create the suction of the liquid.
• said ejector rod is housed inside the hollow control rod, even if it could be otherwise, without departing from the scope of the invention.
• the ejector rod could be housed within the outer pipette body, around the control rod, and have a low end penetrating inside the gripping device to be able to apply the ejection force specific to the present invention, on the upper end of the piston.
• the pipette comprises a control button arranged at the upper end of the control rod, and an ejection button arranged at the upper end of the ejector rod. Said button ejection is then preferably arranged between the control button and a pipette body forming a handle.
• said ejection button is carried by a support member mounted on the ejection rod and passing through an oblong passage made in the control rod, said support member being able to slide in said oblong passage.
• said pipette is equipped with elastic return means reminding said ejection rod in a high position relative to said control rod. It is preferentially a compression spring.
• said elastic return means reminding said ejection rod in a high position relative to said control rod are designed such that when an actuation of said ejection button, a first stroke has the effect of causing said control rod with said ejector rod, via said elastic return means, and a second stroke is initiated when the displacement of the control rod is stopped in translation by abutment at the end of said first stroke, said second stroke producing said relative displacement between the ejector rod and the control rod, causing said ejection force on the upper end of said piston.
• the pipette is designed so that at the end of said first stroke, said control rod in abutment places said gripping device at least partially projecting towards the bottom from a pipette tip on which the capillary of said capillary-piston assembly is intended to be fitted.
• said gripping device at least partially projecting towards the bottom from a pipette tip on which the capillary of said capillary-piston assembly is intended to be fitted.
• the lower stop for said control rod is arranged on a lower part of the pipette integrating the tip, and preferably designed to cooperate with a stop provided on said gripping device interposed between said control rod and the low stop.
• the control rod could be equipped with a stop allowing it to come directly on the abutment of the lower part of the pipette, without departing from the scope of the invention.
• the pipette may be single volume sampling, or include a device for adjusting the sample volume to be taken.
• FIG. 1 represents a longitudinal sectional view of a positive displacement sampling pipette, according to a preferred embodiment of the present invention
• - Figure 2 shows a front view of the control rod fitted to the pipette shown in the previous figure
• Fig. 3 is a perspective view of the piston clamp fitted to the pipette shown in Fig. 1;
• FIG. 1 there is shown a positive displacement sampling pipette 1 according to a preferred embodiment of the present invention.
• the pipette 1 has an outer body whose upper part forms a handle 2 for the operator, and whose lower part 4 is tapered, ending down by a tip 6 on which a capillary is intended to be fitted.
• the lower part 4 is mounted preferably screwed on the handle body 2, so as to facilitate assembly / disassembly.
• the pipette incorporates a control rod 8, slidably housed inside the outer body pipette.
• the rod 8 is hollow, and arranged along the longitudinal axis 10 of the pipette. Its upper end protrudes upwardly from the handle body 2, and carries a control button 12 to be actuated by the thumb of an operator holding the body 2 with one of his hands.
• the rod has a non-circular cross section, here of hexagonal or octagonal shape. It is slidably housed through a volume adjusting screw 14 to be sampled, whose inner hollow portion is of complementary shape to the outer surface of the rod 8, and whose outer surface is threaded, mounted screwed onto the lower end of the body forming a handle 2.
• the rotation of the control rod 8 by its knob 12 makes it possible to move the adjustment screw relative to the pipette outer body in the direction of the axis 10, and thus causes a modification of the volume of the sample to be taken.
• the clamp 20 has a body 24 in contact with the lower end 16 of the control rod, extended downwards by two or more jaws.
• two jaws 26 are provided, one made in one piece with the clamp body 24, and the other mounted on the same clamp body.
• Elastic return means to recall the two jaws in the closed position, in which they are retracted radially inwards.
• the slot 30 separating them then has a small dimension.
• the elastic return means urge the jaws 26 radially inwardly, preferably by surrounding these same jaws. It can then be a spring 32 of annular overall shape, the diameter of which can be increased when it is stressed radially outwards.
• the spring 32 takes the form of a spiral spring enclosing the outer surface of the jaws 26.
• each jaw 26 has a chamfered end 36 to facilitate the insertion of the piston, as will be explained below.
• the clamp body 24 has a first shoulder 38 facing downwards, facing and at a distance from a shoulder 40 formed on the lower part 4, near the endpiece 6.
• a return spring 42 is housed in support between these two shoulders 38, 40, to form a return spring in the upper position of the clamp 20 and the control rod located in abutment, in its extension.
• the restoring force developed by this compression spring 42 effectively causes the control rod 8 to adopt its high position relative to the outer body, a conventional high abutment (no shown) being provided for this purpose on the same outer body.
• the clamp 20 comprises a second shoulder 44, also facing downwards and away from the shoulder 40.
• the second shoulder 44 is located further down and radially inwardly relative to the first shoulder 38. It is thus surrounded by the spring 42.
• it is intended to constitute a lower stop for the clamp 20 and the control rod 8 resting on the same clamp.
• the ends 36 of the clamp jaws are in the tip 6, in a retracted position inside the latter.
• the inner diameter of the nozzle also has a value close to the average diameter of the clamp 20 with its jaws 26 in the tight position.
• an ejection rod 46 slidably mounted inside the hollow control rod 8.
• This ejection rod 46 has an outer surface complementary to the inner surface of the control rod 8. Its high end is arranged between the control knob 12 and the handle body 2, and carries an ejection button 48.
• the button 48 is carried by a support member 50 pin-shaped, which is mounted on the ejector rod 8 and which passes through an oblong passage 52 formed in the control rod, shown in Figure 2. The pin 50 is then able to slide in the oblong passage 52 during the relative displacement between the two rods 8, 46, corresponding to sliding in the direction of the axis 10.
• the lower end 54 of the ejector rod 46 is tapered, cylindrical in shape and circular in section. It penetrates within a bore 58 made in the hollow body, through to the gap 60 defined between the clamps.
• the latter defines a shoulder 66 oriented downwards, opposite and at a distance from a shoulder 68 formed on the clamp 20, in the bore 58.
• a return spring 64 is housed in abutment between these two shoulders 66, 68, so as to constitute a return spring in the up position for the ejection rod 46 with respect to the control rod 8 situated on the outside. .
• the restoring force developed by this compression spring 64 effectively causes the ejector rod 46 to adopt its high position relative to the control rod 8, a high stop being achieved by pressing the ejection button surrounding the rod. 8, on the low end of the control knob 12, as can be seen in FIG. 1.
• Such an abutment could alternatively be constituted by the support of the pin 50 on the upper end of the oblong passage 52 formed transversely on the control rod.
• the operator gripping the pipette by the handle 2 engages the tip 6 in a capillary 80 of a capillary-consumable piston assembly 84, preferably arranged in a housing, also called "rack".
• a capillary 80 of a capillary-consumable piston assembly 84 By exerting a vertical downward pressure on the pipette, it obtains the fitting of the capillary 80 on the tip 6, in the manner of fitting a capillary or a conventional cone on the tip of a nozzle.
• the jaws 26 are biased radially outwardly by the support of the upper end of the piston 86 on the chamfered ends 36 of these jaws. This leads to a separation of jaws authorized by the stressing of the spiral spring 32 surrounding these jaws, and allowed by a sufficient bore diameter in the tip 6. Moreover, during this descent, a lower part of the jaws is intended to be protruding of the tip 6 so as to allow greater deformation of these jaws, radially outwardly.
• the piston is in the lower abutment position in the capillary.
• the control rod 8 is kept in the low position until sample collection, during which the control rod rises with the piston to create the aspiration of the liquid.
• the consumable assembly 84 is ejected by means of the ejection rod 46 actuated by its control knob 48.
• the stiffness of the return spring 64 is such that during a first stroke, this spring does not compress and the displacement rod 46 in displacement carries with it the control rod 8. This phase has been shown schematically in FIG.
• the shape of the end 54 of the ejector rod 46 can be optimized to best fit the upper end 86 of the piston 82, so as to promote contact between the two parts, by centering.
• 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.

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• Health & Medical Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Clinical Laboratory Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Life Sciences & Earth Sciences (AREA)
• Physics & Mathematics (AREA)
• Hydrology & Water Resources (AREA)
• Analytical Chemistry (AREA)
• Biochemistry (AREA)
• General Health & Medical Sciences (AREA)
• General Physics & Mathematics (AREA)
• Immunology (AREA)
• Pathology (AREA)
• Devices For Use In Laboratory Experiments (AREA)
• Sampling And Sample Adjustment (AREA)

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Cited By (3)

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Citations (5)

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• 2011
  • 2011-09-19 FR FR1158309A patent/FR2980123B1/fr not_active Expired - Fee Related
• 2012
  • 2012-09-18 BR BR112014004083A patent/BR112014004083A2/pt not_active Application Discontinuation
  • 2012-09-18 CN CN201280044024.6A patent/CN103874546B/zh active Active
  • 2012-09-18 CA CA2844778A patent/CA2844778C/fr not_active Expired - Fee Related
  • 2012-09-18 US US14/345,294 patent/US9804064B2/en active Active
  • 2012-09-18 PL PL12761970.8T patent/PL2758174T3/pl unknown
  • 2012-09-18 WO PCT/EP2012/068294 patent/WO2013041505A1/fr not_active Ceased
  • 2012-09-18 ES ES12761970.8T patent/ES2576956T3/es active Active
  • 2012-09-18 JP JP2014530265A patent/JP6157474B2/ja active Active
  • 2012-09-18 KR KR1020147007189A patent/KR101956375B1/ko not_active Expired - Fee Related
  • 2012-09-18 EP EP12761970.8A patent/EP2758174B1/fr active Active

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