FIELD OF THE INVENTION

The present invention relates to a pipette, and in particular a pipette that utilises disposable tips.

BACKGROUND TO THE INVENTION

Pipettes are devices used to transfer volumes of media, especially aliquots of liquid. Micropipettes are used to accurately transfer relatively small volumes of liquids. Conventional micropipettes are hand-held devices that are used with disposable tips. The tips are placed on the end of a shaft and the micropipette draws liquid into and out of the tip by displacement of air via the shaft.

Typically, the disposable tips are held in an array in a tray or box, and the user will push the shaft of the micropipette onto a fresh tip to mount it on the distal end of the shaft. The user then uses a plunger to draw an aliquot into the tip and subsequently dispense the aliquot. After use, the user will activate a mechanism to eject the used tip from the distal end of the shaft. This can be, for example, by manually depressing a button to cause an arm to physically push the used tip off the distal end of the shaft. The user can then move the micropipette back to the tray to manually load the next fresh tip.

This system is not optimal in many ways. For example, it is an inefficient way of working for the user to manually load and eject each individual tip in this way. According to the present invention, there is provided a pipette comprising; a shaft having a distal end, a dispensing mechanism for dispensing a tip from a tip storage device, a mounting mechanism for mounting the dispensed tip onto the distal end of the shaft, and an ejector mechanism for ejecting the mounted tip from the distal end of the shaft.

Preferably, the pipette further comprises a tip storage device.

Conveniently, the tip storage device comprises a tubular magazine, a box magazine, a clip or a belt.

Advantageously, the tip storage device is integral with the pipette.

Preferably, the tip storage device is removable from the pipette.

Conveniently, the dispensing mechanism, the mounting mechanism, and/or the ejector mechanism are actuated manually, electrically, hydraulically or pneumatically.

Advantageously, the dispensing mechanism, the mounting mechanism, and the ejector mechanism are actuated separately. Preferably, the dispensing mechanism, the mounting mechanism, and the ejector mechanism are actuated by separate control rods.

Conveniently, the dispensing mechanism, the mounting mechanism, and the ejector mechanism operate in unison and are powered by the reciprocating motion of a primary control rod that is moved by a source of power external to the device.

Advantageously, the dispensing mechanism is gravity fed.

According to an aspect of the invention, there is provided a method of mounting a tip on a pipette comprising the steps of providing a pipette as defined above, actuating the dispensing mechanism to dispense a tip from a tip storage device, actuating the mounting mechanism to mount the tip on the distal end of the shaft, and actuating the ejector mechanism to eject the tip from the distal end of the shaft.

Preferably, the method further comprises repeating the steps of actuating the dispensing mechanism to dispense a tip from a tip storage device, actuating the mounting mechanism to mount the tip on the distal end of the shaft, and actuating the ejector mechanism to eject the tip from the distal end of the shaft. The present invention will now be described with reference to the accompanying drawings in which;

Figure 1 is a schematic view of a prior art pipette with a disposable tip fitted,

Figure 2 is a schematic view of a prior art pipette with a disposable tip being ejected,

Figure 3 is a schematic view of a pipette according to the invention,

Figure 4 is a schematic view of a pipette according to the invention with a dispensed tip,

Figure 4 is a schematic view of a pipette according to the invention with a dispensed tip, and

Figure 5 is a schematic view of a pipette according to the invention with a tip fitted.

Turning to Figure 1 , a prior art pipette 2 is shown of conventional design. The pipette 2 is designed to be held in the hand of a user to aspirate and dispense aliquots of liquid. The pipette 2 has a body 4 to be grasped in the hand of a user. A shaft 6 extends from the body 4 and is connected to a piston which moves a predetermined amount, controlled by the movement of a plunger 14. The shaft 6 has an open distal end 8 onto which a disposable tip 12 can be fitted. An ejector mechanism 10 is shown in the form of an arm extending to the distal end 8 of the shaft 6. As shown in Figure 2, after being used, the tip 12 can be ejected from the pipette 2 by the manual depression of button 16 which moves the arm 10 downwardly to push against the tip 12, ejecting it from the distal end 8 of the shaft 6.

The user then moves the pipette 2 over to a container of fresh tips and presses the distal end 8 of the shaft 6 into a new tip ready for use to aspirate and dispense another aliquot.

As described herein, this is a cumbersome process with several problems. The present invention seeks to address this prior art pipette and method.

Turning to Figure 3, a pipette 20 of the invention is shown. The pipette 20 has a body 22 having a shaft 24 extending therefrom. The shaft 24 has a distal end 26 into which a disposable tip can be mounted. As before, the movement of a piston within the pipette causes the controlled aspiration and dispensing on an aliquot of medium into and out of the disposable tip by the user moving the plunger 28.

The pipette 32 is also provided with a tip storage device 30. In this embodiment, the tip storage device 30 comprises a generally tubular vessel or magazine 30 into which a plurality of tips can be placed (for example by being dropped into the magazine 30 via an open upper end 32). The tips are held within the magazine 30 by a stop. When the user wishes to place a fresh tip onto the pipette, they can depress a button 34 which actuates a dispensing mechanism to release a tip from the magazine, to exit the magazine by the open lower end The dispensed tip will then be caught by a mounting mechanism ready to be mounted onto the distal end 26 of the shaft 24. As shown in Figure 3, the pipette 30 is provided with a mounting mechanism 38, in the form of an elongate arm with a distal end 40 located near the distal end 26 of the shaft 24, and near the lower end 36 of the magazine 30. When a tip is dispensed from the magazine 30, it is caught by the distal end 40 of the mounting mechanism 38, as will be described below.

The pipette 30 is also provided with an ejector mechanism 44 in the form of an arm which extends to near the distal end 26 of the shaft 24. The ejector mechanism 44 is actuated by a button 48 when the user wishes to eject a tip from the pipette 24.

Turning to Figure 4, the situation is shown after a tip 50 has been dispensed from the magazine 30 by actuation of the dispensing mechanism using button 34. The tip 50 has been caught by the distal end 40 of the mounting mechanism 38. By pulling on plunger 42, the tip 50 is raised into contact with the distal end 26 of the shaft 24, thereby mounting it onto the pipette ready for use. This leads to the situation shown in Figure 5.

The user can then perform aspiration and dispensing of a sample of medium with the tip 50 by moving the plunger 28. After that, the user can depress button 48 to move the ejector arm 44 so that the distal end 46 of the ejector mechanism is brought into contact with the tip 50. This contact will force the tip 50 off the distal end 26 of the shaft 24. The user can then depress button 34 to dispense the next tip from the magazine 30, and pull plunger 42 to mount the dispensed tip 50 onto the shaft 24 ready for use. This avoids any need for the user to move the pipette over to a container of tips and manually mount a new individual tip.

In the above embodiment, the tip storage device has been described as a general tubular magazine, integral with the pipette. This is not essential and the tip storage device can be in other forms and configurations, and can be removable instead of integral. For example, the tip storage device can be a magazine of some form containing a plurality of tips ready to be dispensed. The tip storage device can be provided pre-filled with tips, or can be filled and refilled with tips as desired.

The tip storage device can be generally tubular, with the plurality of tips being generally aligned within the storage device (i.e. end to end or stacked together). Alternatively, the tip storage device can take the form of a box magazine, with the plurality of tips being arranged side by side within the magazine.

The tip storage device can contain the tips in a circular or helical configuration. In addition, the tip storage device can contain a plurality of tips arranged in a belt, so that subsequent tips are dispensed by being moved out of the belt when needed (for example by being pushed perpendicularly out of the belt). Other related systems are contemplated, such as tips being arranged in a clip. The dispensing mechanism, mounting mechanism and ejector mechanism can be manually actuated (for example by the user depressing a button or pulling a plunger). The dispensing mechanism, mounting mechanism and ejector mechanism can be powered. For example, the mechanisms can be actuated electrically, hydraulically and/or pneumatically.

The dispensing mechanism, mounting mechanism and ejector mechanism can be operated separately, for example by using separate actuation mechanisms. Alternatively, the dispensing mechanism, mounting mechanism and ejector mechanism can be operated by the same actuation mechanism. For example, the user can depress a single spring-loaded control plunger which first moves the mounting mechanism 40 away from the distal end of the shaft 24 before pushing the ejector arm 44 so that the distal end 46 of the ejector mechanism is brought into contact with the tip 50. This contact will force the tip 50 off the distal end 26 of the shaft 24. The final depression of the control plunger then actuates the dispense button 34 to dispense the next tip from the magazine 30. As the user releases the control plunger the mounting mechanism moves under the return spring force to mount the dispensed tip 50 onto the shaft 24 ready for use, including the retraction of the ejector mechanism 46. This avoids any need for the user to interact with multiple controls to mount each new individual tip.

The present invention relates to a pipette which simplifies the loading of tips. In particular, the present invention relates to pipettes that allow for the semi-automatic attachment and ejection of disposable tips which are stored prior to use in tip storage device, such as an onboard magazine or feeding tube. The magazine can be removable and/or replaceable. In this specification, reference is made to pipettes and micropipettes. Micropipettes fall within the definition of pipettes and are intended for the transfer of relatively small volumes of media, for example volumes up to 1500 microlitres. As mentioned above, micropipettes are generally used with tips which are, in most cases, provided for single use and are ejected from the pipette after use.

Modern laboratory micropipettes rely on the user to manually press the pipette into a new tip every time a tip is attached. Such tips are typically held in a box or tray holding 96 tips in a 12 x 8 array. To attach a new tip to the end of a pipette the user must open the pipette tip box, align and push the working end of the pipette (the distal end of a shaft) into a tip in this array.

Many pipettes work using air-displacement, which uses a moveable piston within a shaft to displace a volume of air, which in turn draws a corresponding volume of liquid into the tip mounted on the distal end of the shaft (aspiration). The user can then activate the device to move the piston to dispense the withdrawn liquid out of the tip. The user can then eject the used tip from the distal end of the shaft and then attach a new tip ready for further use.

This conventional tip attachment process often requires the use of both hands, produces significant operator muscle strain, takes time and presents a significant risk of contamination to unused tips via the frequent opening and shutting of a tip box in a biological safety cabinet or a chemical laminar flow hood. This practice has remained largely unchanged since the introduction of the adjustable micropipette several decades ago.

The present invention addresses this cumbersome tip attachment process with a simpler operation that combines the ejection of a used tip, the dispensing of a new tip, and the attachment of the new tip to the pipette in a position ready for use.

This simplification of practice enabled by the invention reduces the time needed for liquid handling operations using pipettes. In common use, a significant portion of the total time associated with a pipetting operation is occupied by the pipette user manually locating the pipette at the pipette tip box ready for the attachment of a tip.

The removal of the need to move the pipette to and from a tip box or vice versa during a liquid handling operation reduces user strain and removes the need to repeatedly change the angle of the pipette held in the user’s hand, significantly reducing injuries and pain associated with wrist torsion.

The entire operation of mounting a pipette tip, using it and ejecting the used tip can now be feasibly done single handedly without the use of a secondary hand to open a tip box.

The containment of unused tips within an integral magazine prior to use reduces the change of unused tips being contaminated by material from the substance being pipetted or by the surrounding environment. In most automated pipetting the robotically-controlled pipette moves independently of the supply of pipette tips, necessitating the movement of the robotic arm (or similar) to move back to a tip retrieval position in a manner similar to current manual pipetting practice. This inefficiency is addressed by the position of the feed of tips ready for use next to the working end of the pipette body with a mechanism as described herein.

The invention primarily relates to the application of this technology to a handheld pipette that uses one tip at a time and the mechanism for the attachment and the removal of the pipette tip is actuated by a simple press of a control button or lever by the user in a manner similar to current tip ejection buttons and levers. This does not require electrical or other mechanical power to operate although the invention can be applied in automated pipetting and liquid handling systems that may use a source of mechanical power other than user actuation and may make use of multiple parallel pipetting channels. The use of a small electric motor or similar to actuate the mechanism within a handheld micropipette is also possible.

This action can be achieved by a mechanism that requires the use of four components in turn. First a catchment arm is used to hold a pipette tip against the dispensing portion of the pipette. This arm can move vertically to pull a tip against the dispensing portion of the pipette, it can also move perpendicular to the vertical travel to move out of the way of any ejected tip as it falls off the pipette. This movement is advantageous when an ejector mechanism similar to that in a standard pipette, is used to push off any present tip that has already been used. Preferably, a magazine is also used to hold tips ready for use in a stack along the side of the pipette body. Within or beside this magazine a dispensing mechanism in the form of an arm can be used to push pipette tips out of the magazine and down into the catchment arm where they can be moved up and into contact with the distal end of the shaft of the pipette.

Whilst specific embodiments of the present invention have been described above, it will be appreciated that departures from the described embodiments may still fall within the scope of the present invention.