Liquid handling device, and use of hollow plunger

Abstract

To provide a convenient liquid handling device and method having different dosing volume ranges available for aspiration and dispensation.SOLUTION: According to an example aspect of the present invention, there is provided a liquid handling device based on air displacement principle, comprising: a cavity comprising a first chamber and a second chamber; and a plunger movable inside the cavity to apply a vacuum or pressure to the inside of the cavity. The first chamber is configured to provide a first dosing volume range. The second chamber together with the first chamber is configured to provide a second dosing volume range, which is larger than the first dosing volume range. The first chamber and the second chamber are connected by a closable fluid connection. The fluid connection is provided through the plunger.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a liquid handling device which operates according to the air displacement principle. [Background technology]

[0002] Air displacement pipettes generally comprise a cylindrical cavity and a plunger adapted to move within the cavity. The plunger can be actuated manually by a user or automatically by an electric motor. As the plunger moves upwards within the cylinder, liquid is aspirated into a tip attached to the bottom or open end of the cylinder. As the plunger moves downwards, liquid is expelled from the tip.

[0003] In conventional air displacement pipettes, the range of injection volumes available for aspiration and dispensing is determined by the dimensions of the pipette's cylinder and plunger, in particular the diameter and length of the cylinder and plunger, as well as the stroke length of the plunger. Conventionally, only a single volume range is available and cannot be modified, such as to increase or decrease. Within this volume range, it is possible to select the desired injection volume for a particular pipetting operation by adjusting the plunger stroke length, i.e., the travel distance of the plunger. Setting the stroke length to the shortest value makes the smallest volume available within the volume range. Conversely, setting the stroke length to the longest value makes the largest volume available within the volume range.

[0004] Generally, the accuracy of a large volume pipette is limited when using volumes at the lower end of its volume range, therefore a minimum injection volume is always specified.

[0005] Fixed volume air displacement pipettes also exist that do not allow for adjustable plunger stroke length, and instead provide a fixed injection volume rather than an arbitrary volume range.

[0006] The present invention is intended to solve at least some of the problems existing with known air displacement pipettes. Summary of the Invention

[0007] The invention is defined by the features of the independent claims. Some particular embodiments are defined in the dependent claims.

[0008] According to a first aspect of the invention there is provided a liquid handling device based on the air displacement principle, comprising: a cavity including a first chamber and a second chamber; a plunger movable within the cavity to apply a vacuum or pressure within the cavity; Equipped with the first chamber is configured to provide a first injection volume range; the second chamber is configured with the first chamber to provide a second injection volume range greater than the first injection volume range; the first chamber and the second chamber are connected by a closable fluid connection; A liquid handling device is provided, wherein the fluid connection is provided through the plunger.

[0009] According to a second aspect of the present invention there is provided a liquid handling device comprising: a cavity including a first chamber and a second chamber, the first chamber having a first volume and the second chamber having a second volume greater than the first volume; a plunger configured to move within the cavity to apply a vacuum or pressure within the cavity, thereby aspirating or dispensing liquid to / from a tip attached to an open lower end of the cavity; A liquid handling device is provided, wherein the first chamber and the second chamber are connected by a closeable fluid connection.

[0010] According to a third aspect of the present invention, 1. Use of a hollow plunger in an air displacement liquid handling device, the hollow plunger acting as a fluid connection between two portions of a cavity within which the plunger is configured to move, comprising: A use is provided, wherein the fluid connection is configured to be closable to reduce a volume range of the liquid handling device.

[0011] Various embodiments of the first or second or third aspect may include one or more features of the following bulleted list: The first injection volume range or the first injection volume is configured to be available when the fluid connection is closed. The second injection volume range or the second injection volume is configured to be available when the fluid connection is open. The cavity is composed of the first chamber and the second chamber. The cavity has an open lower end configured to hold a tip, such as a disposable tip, for receiving liquid, e.g., a plastic disposable tip. The first chamber is substantially cylindrical. The second chamber is substantially cylindrical. The second chamber has a larger diameter than the first chamber. The plunger is sealed against the inner surface of the cavity, typically the inner surfaces of both chambers. The plunger is sealed against the inner surface of the second chamber by a flange on the outer periphery of the plunger. The plunger is hollow at least partially along its length. The plunger is hollow over its entire length. The hollow portion or the hollow plunger provides the closable fluid connection, or at least a part of the closable fluid connection, between the first chamber and the second chamber. At least a portion of the length of the plunger, preferably the entire length above the lower end of the plunger, is hollow. The fluid connection comprises a channel extending into the interior of the plunger from a lower end of the plunger to an opening in a side wall of the plunger, so that preferably the plunger is hollow over at least part of its length. The liquid handling device comprises a closure mechanism configured to open and close the closeable fluid connection, in particular to open and close the opening in the side wall of the plunger. The closure mechanism includes a rod or bar within a hollow portion of the plunger. The rod is movable, usually vertically, within the hollow portion in order to open and close the fluid connection, in particular to open and close the opening. The rod is movable within the hollow about its vertical axis in order to open and close the fluid connection, in particular to open and close the opening. The closing mechanism is actuated by an electric motor, such as a solenoid motor. The liquid handling device is an air displacement pipette. The liquid handling device is an air displacement pipette with a fixed plunger stroke length. The liquid handling device is an air displacement pipette with an adjustable plunger stroke length. The liquid handling device is a handheld pipette, preferably a handheld air displacement pipette. The liquid handling device is an automated liquid handling station. The liquid handling device is a single channel or a multi-channel liquid handling device. The fluid connection is provided through the plunger. Effect of the Invention

[0012] The present invention can provide a convenient way to have two alternative, typically different, volume ranges with one pipette.

[0013] The present invention may be particularly beneficial in manual hand-held pipettes because of the space-saving implementation: two volume ranges can be provided without affecting the overall dimensions of the pipette.

[0014] Furthermore, the present invention allows several pipetting steps to be performed with substantially different dispensing volumes, since the pipette provides the user with two volume ranges, avoiding changing from using one pipette to another pipette with a different volume range in the middle of a dispensing sequence. [Brief description of the drawings]

[0015] [Figure 1] 1 illustrates a liquid aspirating and dispensing head or pipette according to one embodiment of the present invention. [Diagram 2] 1 illustrates a liquid aspirating and dispensing head or pipette according to one embodiment of the present invention. [Diagram 3] 1 illustrates a liquid aspirating and dispensing head or pipette according to one embodiment of the present invention. [Figure 4] 1 illustrates a liquid aspirating and dispensing head or pipette according to one embodiment of the present invention. [Diagram 5] 1 illustrates a plunger and rod according to one embodiment of the present invention. [Figure 6] 1 illustrates a plunger and rod according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] (definition) In the present context, the term "liquid handling device" generally includes devices configured to aspirate and dispense liquids, usually in volumes of less than 20 ml.

[0017] In the present context, the term "pipette" typically refers to a handheld liquid dispensing device, such as a mechanical or electronic pipette, and may also refer to the pipetting head in an automated liquid handling robot or station.

[0018] In this context, the term "fluid" normally refers to air.

[0019] In the present context, the term "plunger" is synonymous with the term "piston."

[0020] In the present context, the term "plunger stroke length" is synonymous with the terms "plunger travel length" and "plunger travel distance."

[0021] In the present context, the expression "connected by a fluid connection" typically refers to being connected by a channel for passing a fluid (such as air). The term "fluid connection" typically refers to an air connection or a pressure channel.

[0022] The present invention preferably relates to an air displacement pipette or dispensing device in which a plunger can be moved within a cavity to apply vacuum or pressure within the cavity and thereby aspirate or dispense liquid to / from a tip attached to the open lower end of the cavity.

[0023] As used herein, the term "volume range" typically refers to the injection volume range of a pipette, i.e., the range of liquid volumes that a pipette is configured to aspirate and dispense by moving the plunger within a cavity over an adjustable plunger travel distance.

[0024] Some embodiments of the present invention are applicable to air displacement pipettes with adjustable plunger stroke length, said adjustment making it possible to have a range of available injection volumes.

[0025] Some embodiments of the present invention are applicable to air displacement pipettes having a fixed plunger stroke length.

[0026] For pipettes with adjustable plunger stroke length, it has been observed that the novel chamber structure of the present invention can provide a range of alternative injection volumes in a single pipette or liquid handling device.

[0027] It has also been observed that for pipettes with fixed plunger stroke lengths, the novel chamber structure of the present invention allows an alternative constant injection volume to be provided in a single pipette or liquid handling device.

[0028] In one embodiment, a liquid handling device based on an air displacement principle is provided, comprising a cavity including or consisting of a first chamber and a second chamber, and a plunger movable within the cavity to apply a vacuum or pressure within the cavity. Movement of the plunger typically displaces air within the cavity and aspirates and dispenses liquid from and to a tip attached to an end of the cavity, the end being an open lower end of the cavity.

[0029] The cavity typically consists of or includes two separate parts, each having its own capacity or volume for holding air, the parts being connectable to form a single combined volume.

[0030] The first chamber is configured to provide a first injection volume range, such as when used alone, without an air connection to the second chamber.

[0031] The second chamber is typically not used alone, but only in combination or with the first chamber, such that their individual volumes form a single, integrated volume that provides a second injection volume range that is greater than the first injection volume range.

[0032] Within each volume range, a user can conventionally set a desired injection volume for a particular pipetting operation by adjusting the plunger stroke length.

[0033] The first and second chambers are usually connected by a closable fluid connection. Preferably, the fluid connection can be opened and closed as required when performing a pipetting operation with the pipette, in order to change from a smaller volume range to a larger volume range or vice versa, respectively. As a result, it may be appropriate to change the tip to a larger volume tip or to a smaller volume tip.

[0034] In some embodiments, the fluid connection is provided through the plunger, for example a closable channel through at least a portion of the length of the plunger may function as the closable fluid connection.

[0035] In some embodiments, the fluid connection comprises a closeable hose or tube.

[0036] In one embodiment, the first injection volume range is configured to be available when the fluid connection is in a closed state.

[0037] A channel is provided for air to be discharged from the top of the second chamber above the flange when the fluid connection between the first chamber and the second chamber is closed, and when the fluid connection is open and the second chamber is in use, the channel for air to be discharged from the top of the second chamber above the flange is closed.

[0038] In one embodiment, the second injection volume range is configured to be available when the fluid connection is open.

[0039] In one embodiment, the cavity includes an open lower end configured to hold a tip for receiving liquid, such as a disposable plastic tip.

[0040] Preferably, the first and second chambers are cylindrical, they may also have any other suitable shape to fit the outer dimensions of the liquid handling device, for example the shape of the body of the liquid handling device.

[0041] In some embodiments, the second chamber has a larger diameter than the first chamber. The second chamber may have a smaller height than the first chamber.

[0042] Preferably, the height of said first chamber is equal to or greater than the plunger stroke length.

[0043] Preferably, the height of said second chamber is equal to or greater than the plunger stroke length.

[0044] The plunger is typically sealed against the inner surface of the cavity at a predetermined location along the height of the cavity.

[0045] The plunger may be sealed against the inner surface of the second chamber by a flange provided on the periphery of the plunger, for example by providing a seal between the outer edge of the flange and the inner surface of the second chamber.

[0046] In one embodiment, the plunger is hollow at least partially along its length, the hollow portion typically providing the, or at least a portion of, the closable fluid connection between the first and second chambers.

[0047] At least 10% of the plunger's length upward from its lower end may be hollow, such as at least 20%, for example at least 30%, such as at least 40%, for example at least 80%.

[0048] The entire plunger may be hollow.

[0049] In one embodiment, the fluid connection comprises a channel extending into the interior of the plunger from a lower end of the plunger to an opening in a side wall of the plunger, such that the plunger is hollow along at least a portion of its length.

[0050] The liquid handling device may comprise a closure mechanism configured to open and close the closeable fluid connection, in particular to open and close the opening in the side wall of the plunger.

[0051] For example, the closure mechanism may include a rod or bar within a hollow portion of the plunger, the rod being movable within the hollow portion to open and close the fluid connection.

[0052] The closing mechanism is preferably actuated by an electric motor, such as a solenoid motor. The closing mechanism can also be actuated manually by moving the rods up and down respectively.

[0053] The liquid handling device may be a handheld pipette, preferably a handheld air displacement pipette.

[0054] The liquid handling device may be an automated liquid handling robot or station.

[0055] The liquid handling device may be a single channel device or a multi-channel device.

[0056] In some embodiments, the present invention provides for the use of a hollow plunger in an air displacement liquid handling device, the hollow plunger acting as a fluid connection between two portions of a cavity in which the plunger is configured to move, typically the fluid connection being configured to be closable to reduce the injection volume range of the liquid handling device.

[0057] In one embodiment, at least two volume ranges are provided, such as at least three volume ranges. In one preferred embodiment, exactly two volume ranges are provided.

[0058] The volume ranges may or may not overlap.

[0059] In the following, an embodiment having just two volume ranges, such as a first volume range and a second volume range, is described.

[0060] Typically the maximum value of both volume ranges is less than 10000 μl.

[0061] In one embodiment the two volume ranges have a maximum of 1000μl and 5000μl, or such as 100μl and 1000μl, or such as 30μl and 300μl, or such as 20μl and 200μl, or such as 10μl and 200μl, or such as 10μl and 100μl.

[0062] In one embodiment, the volume ranges may have the same or substantially the same minimum volume, for example the volume ranges provided may be 1-100 μm and 1-1000 μm.

[0063] In one embodiment, the volume ranges may have the same or substantially the same maximum volume, for example the volume ranges provided may be 10-1000 μm and 1-1000 μm.

[0064] Figures 1-4 show a liquid aspirating and dispensing head or pipette according to an embodiment of the present invention. Two alternative liquid injection volume ranges are provided. Similar parts are included in Figures 1-4 and are labeled with the same reference numbers.

[0065] The pipette comprises a plunger 11 movable within a cavity. When the plunger moves upwards, liquid is aspirated into a tip attached to the open lower end 12 of the pipette. The tip is not shown. When the plunger moves downwards, liquid is expelled from the tip. The pipette works on the principle of air displacement. There is therefore no direct contact between the plunger and the liquid.

[0066] In Figures 1 and 2, the plunger 11 is in its lowest position, while in Figures 3 and 4, the plunger 11 is in a raised position.

[0067] A smaller volume range is used in Figures 1 and 3. A larger volume range is used in Figures 2 and 4.

[0068] Two alternative volume ranges are provided in a pipette by having a two-part cavity containing two chambers which can be connected by the fluid connection. Typically, the chambers can be separated from each other by closing the fluid connection.

[0069] A first chamber 13, which is a chamber carrying a smaller volume area, is formed in the lower part of the cavity. The lower part has a cylindrical shape. The first chamber is defined by the inner wall of the lower part of the cavity and by the plunger.

[0070] A second chamber 14, which is used in conjunction with the first chamber to provide a larger volume range, is formed in the upper part of the cavity. The upper part also has a cylindrical shape, but has a larger diameter than the lower part of the cavity. The lower and upper parts of the cavity may be referred to as the lower and upper cylinders, where the terms "upper" and "lower" refer to the positions in which the pipette is normally used, such as during aspirating and dispensing operations.

[0071] The plunger 11 is sealed against the inner walls of the cavity, in particular against the inner walls of both the lower and upper cylinders.

[0072] The seal 15 between the plunger 11 and the inner surface of the lower cylinder 13 is shown in the figure.

[0073] Furthermore, the plunger has a flange 16 on its outer periphery. A seal 17 is provided between the flange 16 and the inner wall of the upper cylinder 14. The second chamber is defined by the inner wall of the upper cavity and the flange.

[0074] In this embodiment, the plunger 11 is hollow, resulting in a channel 18 between the two chambers. The hollow part of the plunger is in fluid (pneumatic) connection with the interior of the upper cylinder by an opening 19 in the side wall of the plunger.

[0075] In this embodiment, the plunger is hollow throughout its entire length, located within the lower and upper cylinders.

[0076] The closure mechanism comprises a rod 20 located at the top of the hollow interior of the plunger and movable up and down within the hollow plunger. The lower end 21 of the rod is sealed against the inner wall of the plunger. The rod is configured to open and close the opening 19 and simultaneously the channel 18 when a larger and smaller volume range is desired, respectively. Moving the rod downwards within the plunger, through the opening and below the opening closes the connection between the chambers. Moving the rod upwards within the plunger, through the opening and above the opening restores or opens the fluid connection between the chambers via the hollow plunger and the opening.

[0077] Thus, in this embodiment, the smaller chamber works according to the plunger principle and the larger chamber works according to the cylinder principle.

[0078] "Plunger principle" refers to an arrangement in which the volume of air displaced is defined by the volume of a plunger within a chamber.

[0079] "Cylinder principle" refers to an arrangement in which the volume of air displaced is defined by the volume of the cylinder itself.

[0080] Thus, in these two configurations, the dispensing accuracy is determined by the dimensional accuracy of the plunger and by the dimensional accuracy of the cylinder, respectively.

[0081] Alternatively, the closing mechanism may comprise a rod 20 movably mounted within the hollow plunger 11 around its vertical axis. In other words, the rod 20 may rotate within the hollow plunger 11 around its vertical axis. The rod 20 has a circular cross section with a first cut or chamfer extending from the lower end 21 of the rod towards the upper end 22 of the rod and a second cut or chamfer extending from the upper end 22 of the rod towards the lower end 21 of the rod. The first cut or chamfer may be on the opposite side of the rod cross section to the second cut or chamfer. When the rod 20 is inside the plunger 11, the first cut or chamfer and the second cut or chamfer form a first plunger chamber 23 and a second plunger chamber 24, respectively, between the rod 20 and the plunger 11. The volume of the second plunger chamber 24 may be greater than the volume of the first plunger chamber 23, or vice versa. When the rod 20 is moved about its vertical axis inside the plunger 11, the first plunger chamber 23 or the second plunger chamber 24 may be rotated while in communication with the opening 19. The rod 20 is thus configured to open and close the opening 19.

[0082] 5 and 6 show a plunger 11 and a rod 20 movable within said plunger 11 about its vertical axis.

[0083] Figure 5 shows the rod 20 in a position when the first plunger chamber 23 is in fluid communication with the opening 19 and the channel opens towards the lower end of the rod 21. A larger volume range is now utilized.

[0084] Figure 6 shows the rod in a position when the second plunger chamber 24 is in fluid communication with the opening 19 and the channel opens towards the upper end of the rod 22, with a smaller volume range being utilized.

[0085] It is understood that the disclosed embodiments of the invention are not limited to the particular structures, process steps, or materials disclosed herein, but are intended to extend to equivalents thereof as recognized by those skilled in the relevant art. It is also understood that the terminology used herein is used for the purpose of describing particular embodiments only, and is not intended to be limiting.

[0086] References throughout this specification to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment.

[0087] As used herein, a plurality of items, structural elements, components, and / or materials may be presented in a common list for convenience; however, these lists should be construed as if each member of the list were individually identified as a separate and unique member. Thus, any individual member of such a list should not be construed as a de facto equivalent of any other member of the same list based on their presentation in a common group, unless otherwise indicated. Moreover, various embodiments and examples of the invention may be referenced herein along with alternatives for the various components thereof. Such embodiments, examples, and alternatives should not be construed as de facto equivalents of each other, but rather as separate and autonomous representations of the invention.

[0088] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided, such as examples of lengths, widths, shapes, etc., to provide a thorough understanding of embodiments of the invention. However, one of ordinary skill in the art will recognize that the invention may be practiced without one or more of the specific details, or with other methods, materials of construction, etc. In other instances, well-known structures, materials, or operations have not been shown or described in detail to avoid obscuring aspects of the invention.

[0089] While the above examples serve to illustrate the principles of the invention in one or more specific applications, it will be apparent to those skilled in the art that numerous changes in the form, use and details of implementation may be made without the exercise of inventive faculty and without departing from the principles and concepts of the invention. Accordingly, it is not intended that the invention be limited, except as by the claims set forth below.

[0090] The verbs "comprise" and "include" are used in this document as open limitations that do not exclude or require the presence of unrecited features. Features recited in the dependent claims are freely combinable with one another, unless otherwise noted. Furthermore, the word "a" or "an", i.e. the singular form "a", "an", "the ... [Industrial Applicability]

[0091] The present invention is industrially applicable at least in mechanical or electronic handheld pipettes and automated liquid dispensing robots. [Explanation of symbols]

[0092] 11 Plunger 12 Open lower end of pipette 13 First Chamber 14 Second Chamber 15 Seal 16 Flange 17 Seal 18 Channels 19 Opening 20 Rod 21 Lower end of rod 22 Rod upper end 23 First plunger chamber 24 Second Plunger Chamber

Claims

1. A liquid handling device based on the principle of air displacement, A cavity including the first chamber and the second chamber, The cavity is equipped with a plunger that is movable within the cavity for applying vacuum or pressure to the cavity, Here, the first chamber is configured to provide a first injection volume range or a first injection volume. The second chamber is configured, together with the first chamber, to provide a second injection volume range or second injection volume that is larger than the first injection volume range or the first injection volume. The first chamber and the second chamber are connected by a closable fluid connection, A liquid handling device in which the fluid connection portion is provided through the plunger.

2. The liquid handling apparatus according to claim 1, wherein the first injection volume range or the first injection volume is configured to be available when the fluid connection is closed.

3. The liquid handling apparatus according to claim 1 or 2, wherein the second injection volume range or the second injection volume is configured to be available when the fluid connection is open.

4. The liquid handling apparatus according to claim 1, wherein the first chamber and the second chamber are cylindrical.

5. The liquid handling apparatus according to claim 1, wherein the second chamber has a larger diameter than the first chamber.

6. The liquid handling apparatus according to claim 1, wherein the plunger is sealed to the inner surface of the cavity, typically to the inner surfaces of both chambers.

7. The liquid handling apparatus according to claim 1, wherein the plunger is sealed to the inner surface of the second chamber by a flange provided on the outer circumference of the plunger.

8. The liquid handling apparatus according to claim 1, wherein the plunger is hollow in at least a portion of its length, and the hollow portion provides the closable fluid connection between the first chamber and the second chamber, or at least a portion of the closable fluid connection.

9. The liquid handling apparatus according to claim 1, wherein at least a portion of the length of the plunger is hollow.

10. The liquid handling apparatus according to claim 1, wherein the fluid connection portion has a channel extending into the plunger from the lower end of the plunger to an opening in the side wall of the plunger, and as a result, the plunger is hollow in at least one part along its length.

11. A closing mechanism configured to open and close the aforementioned closable fluid connection portion, A liquid handling apparatus according to claim 1, comprising:

12. The liquid handling apparatus according to claim 1, wherein the closing mechanism has a rod in the hollow portion of the plunger, wherein the rod is movable up and down within the hollow portion to open and close the fluid connection portion.

13. The liquid handling apparatus according to claim 1, wherein the closing mechanism is operated by an electric motor.

14. The liquid handling device according to claim 1, wherein the liquid handling device is a handheld pipette.

15. The liquid handling apparatus according to claim 1, wherein the liquid handling apparatus is an automatic liquid handling station.

16. The liquid handling apparatus according to claim 1, wherein the liquid handling apparatus is a single-channel or multi-channel liquid handling apparatus.

17. The use of a hollow plunger in an air-displaced liquid handling apparatus, wherein the hollow plunger functions as a fluid connection between two parts of a cavity in which the plunger is configured to move, The fluid connection is configured to be closable in order to reduce the injection capacity range or injection capacity of the liquid handling device.

18. A liquid handling device, A cavity comprising a first chamber and a second chamber, wherein the first chamber has a first volume and the second chamber has a second volume greater than the first volume, A plunger configured to move within the cavity to apply vacuum or pressure to the cavity, thereby drawing or dispensing liquid to / from a tip attached to the lower end of the cavity's opening, A liquid handling device comprising the first chamber and the second chamber connected by a closable fluid connection.

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