DE7236386U - HAND PIPETTES - Google Patents

Description

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PATENT ADVOCATE DR. HANS-GUNTHER EGGERT ₁ DIPLOMA CHEMIST

3 COLOGNE Si ₁ OBERLÄNDER UFER 90

Cologne, October 3, 1972 Ax / Me

Medical Laboratory Automation, Inc., New York Io55o, USA

Hand pipettes

The invention relates to hand-held pipettes, for / lie disposable bare Tips are used into which a liquid is sucked, in particular an automatic removal device these tips after use.

During the last few years the common mouth pipette has become more and has been displaced by hand pipettes. The mouth pipette is completely satisfactory to use and can even by the trained technician who handles it very well and dispenses liquids from it with great accuracy may, be preferred, however, has it compared to handheld pipettes, especially those that are suitable for use of disposable tips. have several disadvantages. In the first place it is necessary for the oral pipette that there is a certain ease of sucking a measured amount of liquid into the Pipette and for dispensing precise amounts of liquid from the Developed pipette. Second, when used for pipetting liquids from different samples,

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e.g. from different blood plasma samples when carrying out tests to determine the prothrombin time, for each sample a clean pipette can be used. A third disadvantage of oral pipettes is that they can be carelessly used This can result in samples of biological fluids, e.g. plasma or blood cells being sucked into the mouth risk of infection with pathogenic microorganisms contained in the samples.

The advantages of hand held pipettes with disposable tips are obvious. Relatively untrained personnel can Aspirate and dispense exact quantities of a liquid. This only depends on the accuracy of the mechanism of the Pipestocked. Disposable tips are clean when packaged and are thrown away after each use, so At their relatively low price, less effort is required than to clean mouth pipettes again is. Furthermore, since they are discarded after each use, they eliminate the possibility of cross-contamination between different samples that are being pipetted.

The disposable tips used for handheld pipettes are in generally elongated, conical parts made of a suitable plastic that is attached to the conical end of the actual pipette can be clamped. In use, the pipette is inserted into the disposable tip with sufficient force pressed to ensure that the tip is held in place in the friction fit while liquid is in it is sucked in and discharged from it. After this use, the tip can be peeled off and thrown away, by removing it with one hand while holding the pipette with the other hand. It is also possible, Provide parts for removing the tip that slide the disposable tip from the pipette while using the pipette

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is brought into contact with the tip removing part. With another part of the removal of the tip it is possible the disposable tip to guide a bar, whereupon it is removed by pulling the lipette upwards.

The invention relates to a pipette with means for removing the disposable tip from the pipette after use without the need for removal tools the tip and without the need for the operator to touch the disposable tip. The invention further comprises means to limit the force with which the operator can press the pipette into the disposable tip when he is holding it on the Pipette attached.

The pipette according to the invention has a conical end over which a disposable tip is clamped, and a Sleeve provided - the one above the. Pipette body pushed and is pushed away from the conical end of the pipette with spring force. The sleeve attaches to one on the end of the pipette the attached disposable tip so that it presses against the disposable tip and pushes it off the pipette.

The invention and its advantages are illustrated below a preferred embodiment described, which is shown in the figures.

FIG. 1 shows a cross section through the pipette.

FIG. 2 is a longitudinal section through the pipette along the line 2-2 of FIG.

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In the following description of the invention, attention should be paid aimed at the actual pipette first. A relatively elongated tube Io, which is preferably made from is made of stainless steel, ^ .m press fit on a Connection point loa connected to or soldered to a hollow cylindrical member. The peripheral surface of the distal The end of the tube Io can be slightly conical / to make it easier to clamp the plague in a disposable tip 4o » The cylindrical member 11 has a reduced diameter at the opposite end, and this reduced part is provided with a thread on the outside.

A hollow finger grip part 12, which is essentially the one shown Shape is internally threaded at 13 so that the handle portion 12 is screwed onto the hollow cylindrical member can be. But before the two parts are joined together; will be two four-corner cents 14 in the end of the handle part 12 and inserted against the ring 15. When the parts 11 and 12 are screwed together, the square rings 14 are consequently set in a groove which is formed by the end of the hollow cylinder 11 and the ring 15. The ring 15, which is a separate part, exercises a axial Kraft'auf the square rings, creating an inward radial sealing force is exerted on the piston 21. As the picture shows, the square rings serve as airtight seal around the pipette piston. The other end of the handle piece 12 is also internally threaded at 16. A retaining nut 17 with an inwardly curved edge is provided with an external thread which is connected to the threaded part 16 of the handle piece 12 is screwed

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The piston assembly 2o of the pipette has a piston which is knurled at one end and with this end ^ in a press fit is inserted into a finger-operated cap 22. The opposite end of the piston 21 extends to each Time during its back and forth movement for filling and emptying the pipette through the square rings 14. The square rings wrap snugly around the flask so that an airtight seal is maintained. A decorative one Insert 23 can be provided to give the pipette a nice appearance, especially if it is one colored plastic insert. A compression spring 24 presses the piston assembly 2o into a position in which the flange the cap 22 pushes against the edge 19 of the retaining nut 17. When the piston assembly 2o against the action of the spring is moved, the movement is finally brought to a standstill in that the flange 25 is against the shoulder 26, which is formed on the inside of the handle part 12. It is obvious that the capacity of the pipette according to the Invention depends on the distance that the Koibenbaugruppe 2o passes through between the positions of the Shoulder 26 and the edge 19 are determined. It is also evident that the position of the edge 19 as a function how far the nut 17 is screwed into the handle 12 can be changed. As a result, this can The capacity of the pipette can be set very precisely by fine-tuning the position of the nut 17. A locking screw 27 is provided in order to lock the nut 17 in its set position relative to the handle 12.

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The assembly for removing the disposable tip has a sleeve 3o which surrounds the outside of the parts 11 and 12. One end of the sleeve 3o is provided with an internal thread at 31. Furthermore, an inwardly projecting annular flange 32 is provided. A compression spring 33, which is pushed loosely over the tube, rests against the ring 32 and presses the sleeve 3o against the underside of the transverse arms of the handle piece 12. The other The end of the spring 33 is secured by a washer 34 and a C-shaped spring clip 35 - which is attached to the circumference of the Rohres Io formed groove 36 snaps into place, held. A member 37 for pushing off the support is the threaded part of the Sleeve screwed 3o.

The Aufeinanderfo _"3 3 of the measures for assembling the pipette according to the invention is described below as it may seem difficult at first glance to reassemble the pipette through the relatively complicated shapes of its different parts.

The tube Io is first made with a press fit or by soldering connected to the hollow cylinder 11, whereupon the square rings 14 are inserted into the elongated part of the handle 12 and the latter is screwed onto the reduced threaded part of the hollow cylinder 11. The parts assembled in this way are then put into the. Sleeve 3o inserted so far It's going ok. Then the compression spring 33 is pushed over the tube Io and compressed by the washer 34, when the spring clip 35 snaps into the groove 36. The member 37 for pushing off the tip is then over the Tube Io pushed and screwed into the sleeve 3o. Next, the piston assembly is formed by removing the cap 22 is pushed onto the piston 21 in a press fit. the

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The compression spring 24 is pushed over the piston 21, which is guided through the VJffkantringe 14. Now the nut 17 is pushed over the cap 22 and screwed into the handle 12. How far the nut 17 is screwed into the handle 12 depends on the desired capacity of the pipette, which in turn depends on the stroke of the piston. This stroke depends on the distance that the flange 1: 5 covers between the edge 19 of the nut 17, which can be fixed in different positions, and the shoulder 26. When the edge 19 is in the desired position, the locking screw 27 is tightened to lock the nut V in place.

A filler or lining could be adjacent over the piston 21 be pushed against the flange 25 to determine the path that the piston travels when the cap 22 is depressed, To shorten. Such a feed would result in a slight change in the volume of liquid taken up by the pipette enable. Either the piece of chuck could be arranged along the piston 21 and in a desired position, for example, be locked by a locking screw, or chucks of different lengths could be used to-change the stroke length of the piston. When using a filler piece or a lining piece for adjustment the capacity of the pipette, the nut 17 would be used to fine-tune the amount picked up by the pipette To enable liquid volume.

For use, the pipette can be grasped by the operator in the way that is most convenient for him. Either can Pipette is grasped by putting a fist around the sleeve

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is made with either the thumb or the forefinger placed on the insert 23 of the cap 22, or by the Sleeve is held between the index finger and middle finger while the thumb lies comfortably on the cap 22. Naturally the operator can use any grip that proves to be comfortable or expedient. To apply a The pipette is then pressed into the open end of a disposable tip 4o, which is in this way at the end of the Pipette is clamped and sealed. It should be noted that di-, ϊ maximum engaging force that is exerted is the force exerted by the spring 33. When the spring 33 to the point where the sleeve 37 on the Splash of the tip 4o hits, has been compressed, no further force can be used to push the parts into one another be exercised. When the force of postponement is increased, only the sleeve 37 is placed more firmly directly against the tip 4o, but the force of application remains constant and is determined by how far the spring 33 is compressed. If this pressure is a little higher is as necessary to ensure a good fit and a good seal, that is for a good seal and a good finish optimizes the required amount of force while keeping it to the minimum is reduced, which is necessary for the exercise of their function. This eliminates any uncertainty on the part of the operator regarding the proper pressure to be applied to a good seal between the pipette and its disposable tip to achieve. The piston assembly is then depressed until the flange 25 meets the shoulder 26. Through this a volume of air is expelled from the tube Io that the Cross-sectional area of the piston 21 multiplied by the

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Path length of the piston, i.e. the distance between the shoulder 26 and the rim 19 minus the thickness of the flange 25 entsoricht "Die DichtiiinoHTj, nrr ^ 14" 8V? M !! 2rlei3ten ^ cLSSS CLi = all air is expelled from the pipe Io and no air escapes along the piston 21. The disposable tip 4o is then introduced into the liquid to be pipetted and the piston assembly 2o released before the pipette is drawn from the liquid. The compression spring 24 moves the assembly 2o into that shown in the figure Position, whereby a liquid volume, which corresponds essentially to the volume of the previously expelled air, in the disposable tip 4o is sucked. The pipette is then removed from the liquid and the one sucked into the tip 4o Liquid is then emptied into a suitable vessel by depressing the piston assembly 20 until it moves by the meeting of the flange 25 (or a piece of liner if this has been inserted into the pipette is) and the shoulder 26 is brought to a standstill. To remove the disposable tip 4o it is only necessary to hold the sleeve 3o and to exert a force against the knurled underside 41 of the transverse arms of the handle 12. As a result, the spring 33 is pressed together and the tube is drawn into the sleeve 37 until the end of the disposable tip pushes against the sleeve 37 and is pushed from the tube Io. . By releasing the force exerted on the handle 12 The compression spring 33 can move the sleeve 3o and the member 37, which pushes off the tip, into the positions shown in the figure return relative positions.

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Claims (7)

- Io protection claims 1. . Hand pipette with a disposable tip attached to the end with the tip bore tapering and sized to over the end the pipette fits, characterized in that the pipette is provided with an organ (3o / 37) which is displaceable placed on the pipette and between: a normal position at a distance from a disposable tip (4o) and a position in which the tip is pushed off, is movable. 2. Hand pipette according to claim 1, characterized by a elastic limb (33) which presses the limb (3o / 37) into its normal position. 3. Hand pipette according to claim 1 and 2, characterized in that that a sleeve (3o / 37) running concentrically to the pipette serves as an organ for pushing off the pipette. 4. Hand pipette according to claim 1 to 3, characterized by a spring (33) which the sleeve (3o / 37) in its normal Position presses. 5. Hand pipette according to claim 1 to 4, characterized by an elongated tube (lo) on which a disposable tip (4o) is clamped, a finger grip (12) which is connected to the elongated tube (lo), a piston assembly (2o) , which is attached in the finger grip (12) so dasa they are moved between two limit positions, .nn, an adjustable nut (17) for fixing one of these positions, means (24) that the 7236386 December 8th, 77 Press the piston assembly (2o) into the position determined by the adjustable nut (17), using as resilient means that presses the sleeve (3o / 37) into its normal position, one pushed over the tube (lo) Compression spring (33) is present, and further characterized by parts (34/35) which are attached to the tube (lo) and fix one end of the compression spring (33) while its opposite end rests against the sleeve (3o) and push it back to its normal position. 6. Hand pipette according to claim 1 to 5, characterized in that the adjustable nut (17) is adjustable with the Finger grip (12) is connected and a locking member (27), the nut (17) in its set position locked. 7. Hand pipette with a disposable tip attached to the end can be characterized by a permanent point (lo), a sleeve (3o / 37) in which the permanent point (lo) slides and from which the permanent point protrudes and a Fedar (33), -that the permanent point (lo) in pushes its prominent position, whereby when inserting the sleeve (3o / 37) into a disposable tip (4o) the permanent tip in the disposable tip (4o) through a Force, which is determined by the spring (33), is clamped in the throw-away tip (4o). 7236386 December 8th, 77