A dosing tool for aspiration and dispensing of a liquid

Abstract

Disclosed is a dosing tool for aspiration and dispensing of a liquid in a removable pipette tip. The dosing tool comprises an ejection element which decouples the pipette tip from the dosing tool when activated. The dosing tool further comprises a variable volume defined by a cylinder, a piston arranged in the cylinder and a distal end of the cylinder. A dosing motor is coupled to the piston, such that the dosing motor drives the piston along an axis A – A within the cylinder, such that the piston is driven in either an aspiration direction away from the distal end of the cylinder whereby the variable volume is increased, or in a dispensing direction toward the distal end of the cylinder whereby the variable volume is decreased. The ejection element is activated when the piston is moved in the aspiration direction to an activation position.

Description

[0001] A dosing tool for aspiration and dispensing of a liquid

[0002] The present disclosure relates to dosing tools, liquid handling devices comprising dosing tools dosing systems and dosing methods for aspirating or dispensing a sample. In particular, the present disclosure relates to the miniaturization of dosing tools by using the same dosing motor for aspiration and dispensing of a liquid in a removable pipette tip and for decoupling the pipette tip from the dosing tool after use. Furthermore, the present disclosure relates to reducing the dead volume of a dosing tool.

[0003] Background

[0004] Automated liquid handling systems are also commonly known as dosing workstations which can perform transfer of sample volumes between various source and destination vessels and containers. In relation to the present disclosure such transfers of sample volumes are done by pipetting where aspiration and dispensing of a sample of a liquid in a removable pipette tip is done by manipulating an air cushion in a dosing tool.

[0005] Such air cushion pipettes have an integrated displacement apparatus for air and at least one seat for a pipette tip. The displacement apparatus is generally formed by a barrel with a movable plunger, such as a piston, guided therein. The piston will typically also act as a seal and / or a sleeve bearing. If the pipette tip is held on the seat, it is connected in a communicating manner with the displacement apparatus. By means of the displacement apparatus, an air cushion can be moved so that the liquid can be sucked into, aspirated, and ejected out of, dispensed, the pipette tip through a tip opening. After use, the pipette tip can be decoupled from the seat and exchanged for a fresh pipette tip.

[0006] Various industries require automated liquid handling systems for the general movement of samples between source and destination vessels and containers and a more precise pipetting system for aspirating and dispensing sample. For example, for pharmaceutical research and clinical diagnostics, there are several types of liquid handling systems used to move samples from one container to another.

[0007] Different types of sample containers, in particular multiple containers are known or may be defined to be used with the automated liquid handling devices. Preferably a sample container holder is set up to hold at least one sample container element. Such container elements are typically compact and thus require machinery that is capable of operating in confined spaced. Concrete examples of sample container element types are Cryo containers, Falcon containers (1 .5 ml and 50 ml), glass containers and glass beakers, slides or multiple containers like microtiter plates (MTP), Deep Well Plates (DWP), cell culture plates, and PCR plates. Multiple containers may have a plurality (from 2 to 10) of individual containers. They can also have a variety (greater than 10), typically 12, 16, 24, 32, 48, 64, 96, 384, 1536 of individual containers. Compared to "normal" microtiter plates, DWP show greater plate and container heights and have more mass. According to American National Standards Institute (ANSI) standard and to recommendations by the Society of Biomolecular Screening (SBS) the dimensions (length x width x height) of microtiter plates are 127.76 mm x 85.48 mm x 14.35 mm. Relevant standards for these standardized dimensions are e.g. ANSI / SBS 1 -2004, ANSI / SBS 2-2004, ANSI / SBS 3-2004 and ANSI / SBS 4-2004. A sample container element defined by any of these standards or another standard is presently referred to as "standard-". Such a type or a standard type may refer to sample container elements having the same structure or may refer to groups of sample container elements which are identical in at least one typical characteristic.

[0008] The maximum sample volume that can be held by a pipetting container or sample container is typically between 0.01 ml and 100 ml, in particular 10-100 micro I, 100-500 micro I, 0.5 5 ml, 5-25 ml, 25-50 ml, 50-100 ml, depending on the type of pipetting container or sample container selected.

[0009] The pipetting can be performed by means of dosing tools or dosing systems with a single pipetting channel. In some applications dosing tools and dosing systems with 8, 12 or up to 96 or more pipetting channels were used and are still in use, for example to address samples in a rectangular grid arrangement.

[0010] This sets a requirement, or limitation, to the size and compactness of the dosing tool. Thus, being able to miniaturize components in the dosing tool is one way of achieving such requirements.

[0011] As will be understood herein another or additional way is to have one part perform several functions. This saves the cost of having multiple parts in the system. Furthermore, if a part, such as a dosing motor, is bulky and generates heat it is preferred to have as few of such part as possible in order to reduce the heat generation. Even further, as discussed the pipetting is done by manipulating an air cushion. The air cushion is for example present in order to prevent that the sample comes in contact with the dosing tool, thus avoiding contamination. However, since air can be compressed and expanded, and the volume of air may significantly change when the temperature changes it is preferred to have an as small air cushion as possible. Typically, the part of the air cushion which is larger than actually needed for dosing is referred to as the dead volume and is generally undesired.

[0012] As will be discussed herein there is a need to provide a dosing tool where the number of bulky and heat generating components are reduced while at the same providing a low dead volume.

[0013] Summary

[0014] In a first aspect there is disclosed a dosing tool for aspiration and dispensing of a liquid in a removable pipette tip. The dosing tool comprises an ejection element which decouples the pipette tip from the dosing tool when the ejection element is activated.

[0015] The dosing tool comprises a variable volume, which is defined by a cylinder, a piston arranged in the cylinder and a distal end of the cylinder. E.g. the cylinder defines a cylinder channel wherein the piston is slidably arranged opposite the distal end of the cylinder. Thus, when the piston is moved in the channel the variable volume will change.

[0016] The dosing tool further comprises a dosing motor coupled to the piston. The dosing motor drives the piston along an axis A - A within the cylinder, such that the piston is driven in either an aspiration direction dA away from the distal end of the cylinder whereby the variable volume is increased, or in a dispensing direction dD toward the distal end of the cylinder whereby the variable volume is decreased. As will be understood herein the dosing motor is not necessarily directly coupled to the piston, but may be indirectly coupled. For example, via a drivetrain.

[0017] Furthermore, as will be further discussed herein, the dosing tool according to the first aspect thus provides that the ejection element is activated when the piston is moved in the aspiration direction to an activation position.

[0018] This provides a dosing tool where only one dosing motor is needed for performing both the dosing action, i.e. aspiration and dispensing, and the ejection of the pipette tip after use of the pipette tip. In particular dosing is performed by driving the piston back and forth along the aspiration direction and the dispensing direction as needed.

[0019] When dosing has been performed and the pipette tip is ready to be disposed the piston is moved in the aspiration direction to the activation position. By providing the activation position in the aspiration direction, e.g. such that the piston is moved opposite the distal end of the cylinder, the dead volume can be reduced.

[0020] In one embodiment according to the current aspect the dosing tool comprises a housing connected or connectable to a carrier arm in a liquid handling device and wherein the cylinder and the dosing motor are fixed to the housing. This provides a frame of reference and structural support for the different elements in the dosing tool.

[0021] In another aspect there is provided a dosing tool for aspiration and dispensing of a liquid in a removable pipette tip, wherein the dosing tool comprises an ejection element which decouples the pipette tip from the dosing tool when activated.

[0022] The dosing tool comprises, a housing connected or connectable to a carrier arm in a liquid handling device. A dosing motor is fixed to the housing and a slide is slidably arranged along an axis A - A relative to the housing between a activation position and a reference position. A drivetrain is arranged in the dosing tool which connects the dosing motor to the slide. The drivetrain may drive the slide in an aspiration direction along the axis A - A towards the activation position or in a dispensing direction in the opposite direction along the axis A - A toward the reference position.

[0023] Even further, the dosing tool comprises a cylinder fixed to the housing. The cylinder defines a channel extending between a proximal end of the cylinder and a distal end of the cylinder.

[0024] A piston is arranged in the channel of the cylinder. The piston is driven by the slide in the aspiration direction toward the proximal end of the cylinder or in the dispensing direction toward the distal end of the cylinder.

[0025] A coupling arrangement is provided for detachably coupling a pipette tip to the dosing tool, where the coupling arrangement is provided at the distal end of the cylinder. The ejection element is arranged at the coupling arrangement and moveable into an activation position for decoupling the pipette tip. In order to direct the motion in the aspiration direction toward the ejection element a motion deflection device is provided for transferring motion from the slide in the aspiration direction to a motion in the dispensing direction for moving the ejection element into the activation position.

[0026] An ejection push rod for transferring the motion from the motion deflection device to the ejection element may in one embodiment be provided between the motion deflection device and the ejection element. The ejection push rod can be a separate element or integrated into the ejection element or the motion deflection device.

[0027] This provides a specific embodiment of a dosing tool as discussed herein providing the same advantages as the dosing tool of the first aspect.

[0028] In particular, only one dosing motor is needed for performing both the dosing action, i.e. aspiration and dispensing, and the ejection of the pipette tip after use of the pipette tip. In particular, dosing is performed by driving the piston back and forth along the aspiration direction and the dispensing direction as needed.

[0029] Similarly, when dosing has been performed and the pipette tip is ready to be disposed the piston is moved in the aspiration direction to the activation position. By providing the activation position in the aspiration direction, e.g. such that the piston is moved opposite the distal end of the cylinder, the dead volume can be reduced.

[0030] As will be discussed herein the dosing tool may be arranged in different configurations and the elements of the dosing tool will be arranged in respective position referring to each of the configurations.

[0031] In one configuration the dosing tool is in a reference configuration, wherein the elements and parts of the dosing tool are in their corresponding reference positions. In the reference configuration the dosing tool will typically have a pipette tip arranged thereon and be the initial configuration for initiating aspiration of a sample into the pipette tip.

[0032] In another configuration the dosing tool is in a maximum stroke configuration, wherein the elements and parts of the dosing tool are in their corresponding maximum stroke positions. The maximum stroke configuration of the dosing tool is the configuration where the largest amount of a sample can be aspirated into the pipette tip. In a further configuration the dosing tool is in an activation configuration, wherein the elements and parts of the dosing tool are in their corresponding activation positions. The activation configuration of the dosing tool is the configuration of the dosing tool where the elements and parts are in a position such that the pipette tip is ejected or decoupled from the dosing tool.

[0033] Description of the drawings

[0034] Fig. 1a, shows a first embodiment of a dosing tool as disclosed herein,

[0035] Fig. 1b, shows a pipette tip for use in a dosing tool as disclosed herein,

[0036] Fig. 2, shows the first embodiment of a dosing tool in a reference configuration, wherein the elements of the dosing tool are in their respective reference positions,

[0037] Fig. 3, shows the first embodiment of a dosing tool in a maximum stroke configuration, wherein the elements of the dosing tool are in their respective maximum stroke positions,

[0038] Fig. 4, shows the first embodiment of a dosing tool in an activation configuration, wherein the elements of the dosing tool are in their respective activation positions, and

[0039] Fig. 5a and 5b, shows a second embodiment of a motion deflection device in a dosing tool as disclosed herein.

[0040] Detailed description

[0041] In one embodiment the dosing motor is coupled to the piston via a drivetrain, wherein the drivetrain comprises a slide coupled to the piston, wherein the dosing motor drives the slide in either the aspiration direction or in the dispensing direction. The purpose of the drivetrain is to transfer force from the motor to the slide and this to the piston coupled thereto.

[0042] The slide may in one embodiment be arranged in the housing such that the slide is moveable relative to the housing.

[0043] For example, in a further or additional embodiment, the drivetrain further comprises a spindle driven by the dosing motor, a spindle nut for converting rotational movement into a translational movement along the piston axis A - A, wherein the spindle nut is connected to the slide, and a piston rod is coupled to the slide and where the piston rod extends along the axis A - A from the slide to the piston arranged in the cylinder. This effectively converts the rotational motion of the motor to a linear motion of the slide and thus also the piston rod.

[0044] As will be understood herein a large number of components will be described with their position relative to the axis A - A. In this context it should be understood that they are not necessarily arranged on that axis, e.g. co-axially, unless specifically stated so. For example, if an element extends or moves along the axis A - A it may for example be parallel to the axis A - A.

[0045] The distal end of the piston rod may in one embodiment provide the piston. The piston may be a separate element, or formed of several separate element such as a piston body and a piston seal. The piston may also form part of the piston rod itself and thus the two elements are integrally formed.

[0046] The slide may also in one embodiment extend transversely to the axis A - A between the spindle and the piston rod.

[0047] For example, in a further embodiment, a first torque control engagement provided to prevent the slide to move transversely to the axis A - A. Providing such torque control engagements in the slide ensures that the piston is moved along the axis A - A and avoids deformation or any undesired movement which may result in an incorrect aspiration or dispensing action.

[0048] In one embodiment the first torque control engagement, or an additional torque control engagement, may comprise a through-going opening extending through the slide along an axis C - C and the housing comprises a slide cylinder extending along the axis C - C where the slide cylinder extends through the through-going opening.

[0049] In one embodiment a motion deflection device is provided to activate the ejection element when the piston is moved in the aspiration direction to the activation position by deflecting the motion in the aspiration direction toward the ejection element in an ejection direction.

[0050] As discussed herein, the purpose of the motion deflection device may further be considered to be to transfer motion in a first direction to a second direction opposite the first direction. E.g. changing the motion of the system in the aspiration direction to motion in the ejection direction. For example, motion may occur in the first direction along the axis A - A whereby the motion deflection device may transfer the motion to a second direction along an axis C - C. The axis A - A and the axis C - C may for example be parallel and the first and the second motion directed opposite to each other as described.

[0051] For example, in one embodiment the ejection direction can be parallel to the dispensing direction, e.g. along the axis A - A as discussed herein.

[0052] For example, in one embodiment the motion deflection device may comprise an activation push rod which is moveable between a neutral position and an activation position, for example along the axis A - A. The activation push rod is moved from the neutral position to the activation position in the aspiration direction when the piston is moved in the aspiration direction to the activation position.

[0053] In a further, or additional, embodiment the motion deflection device can comprise an ejection push rod engaging the ejection element and where the ejection push rod is moveable between a neutral position and an activation position, for example along the axis C - C. The ejection push rod is moved from the neutral position to the activation position in the dispensing direction when the piston is moved in the aspiration direction to the activation position.

[0054] The ejection push rod can in one embodiment be arranged slidably along axis C - C within the slide cylinder. This also enables an even more compact device to be provided.

[0055] In one embodiment the motion deflection device may for example comprise an activation push rod which is moveable between a neutral position and an activation position, for example along the axis A - A, wherein the activation push rod is moved from the neutral position to the activation position in the aspiration direction when the piston is moved in the aspiration direction to the activation position. The motion deflection device may additionally comprise an ejection push rod engaging the ejection element and where the ejection push rod is moveable between a neutral position and an activation position, for example along the axis C - C, wherein the ejection push rod is moved from the neutral position to the activation position in the dispensing direction when the piston is moved in the aspiration direction to the activation position. A gear assembly may be provided for transferring and redirecting motion in the aspiration direction from the activation push rod to motion in the dispensing direction in the ejection push rod.

[0056] Such a gear assembly can for example be provided by a gear wheel arranged between the activation push rod and the ejection push rod, an activation gear rack arranged on the activation push rod, e.g. extending along the axis A - A, and an ejection gear rack arranged on the ejection push rod, e.g. extending along the axis C - C.

[0057] As the activation gear rack and the ejection gear rack engages the gear wheel the direction of the motion of the activation gear rack is redirected through the gear wheel to the ejection gear rack. This provides and embodiment of a motion deflection device as discussed herein. The gear rack and gear wheel setup described herein is similar to a rack and pinion gear as generally known in mechanics.

[0058] In another embodiment a lever assembly may be provided for transferring and redirecting motion in the aspiration direction from the activation push rod to motion in the dispensing direction in the ejection push rod.

[0059] The lever assembly may in one embodiment comprise a lever comprising a first flange and a second flange, wherein the lever is arranged rotatably on a hinge axis extending transversely to the axis A - A and between the activation push rod and the ejection push rod, wherein the first flange extends from the hinge axis toward the activation push rod and the second flange extends from the hinge axis towards the ejection push rod. Thus, when the activation push rod engages the first flange as the activations push rod is moved from the neutral position to the activation position and the second flange moves in the opposite direction of the first flange, the second flange engages the ejection push rod and moves the ejection push rod from the neutral position to the activation position in the dispensing direction.

[0060] In one embodiment the ejection element comprises a sleeve part surrounding at least the distal end of the cylinder and wherein the sleeve part is slidable relative to the cylinder along the axis A - A.

[0061] Detailed description of the drawings

[0062] In the following, detailed embodiments will be discussed in more detail relative to the drawing. The reference numbers are indicated in a XYY format, where X indicates the embodiment, and YY indicates the element in the embodiment. Thus, similar elements or features are indicated by similar YY annotation. E.g. as discussed below the dosing tool of the first embodiment is referenced as 100, whereas the dosing tool of the second embodiment is referenced as 200.

[0063] Moreover, where relevant, reference to a proximal or distal end of an element will be used to indicate orientation and extent. A distal end of an element in the dosing tool will be the end of the element closest to the pipette tip when the tip is arranged on the dosing tool, where the proximal end thus will be the opposite end furthest away from the pipette tip. When referred to the drawings a proximal end will use the reference number of the part followed by one apostrophe, i.e. XYY'. A distal end will use the reference number of the part followed by double apostrophes, i.e. XYY". In operation, the proximal end of an element will typically be the part of the element facing upwards, where the distal end will be the part of the element facing downwards.

[0064] A first embodiment of a dosing tool 100 is shown in Fig. 1 a, 2, 3 and 4, and a pipette tip 111 for use with the dosing tool is shown in Fig. 1 b. The dosing tool comprises a housing 101 on which the components and elements of the dosing tool are arranged in a fixed manner or slidable or movable relative thereto. The housing is shown as one piece, but will typically consist of many pieces that are fixed together via fastening element such as screws. Although the housing preferable is formed of one piece or as few pieces as possible, manufacturing and assembly considerations may require multiple parts to be provided separately and subsequently assembled in order to provide the housing 101. However, common for the part or parts forming the housing is that they form the support frame or structure for the different components of the dosing tool as discussed in the following.

[0065] A dosing motor 102 is fixedly arranged on the housing at a proximal end 10T of the housing opposite a cylinder 103 which is fixedly arranged on the housing at a distal end of the housing.

[0066] The cylinder is fixed to the distal end 101 ” of the housing at a proximal end 103’ of the cylinder. The cylinder extends along a dosing axis A - A between the proximal end 103’ to a distal end 103” of the cylinder. The cylinder is hollow and defines a channel 104 extending along the axis A - A between said proximal and distal ends 103’, 103” of the cylinder 103. A piston 105 is arranged in the channel 104 of the cylinder and is slidable along axis A

[0067] - A in an aspiration direction dA towards the proximal end 103’ of the cylinder or in a dispensing direction dD towards the distal end 103” of the cylinder.

[0068] The dosing motor 102 may rotate in a first and a second direction, such as a clockwise direction and an anti-clockwise direction or vice versa. The dosing motor 102 is coupled to the piston 105 via a piston drivetrain such that when the dosing motor rotates in the first direction the piston slides in the aspiration direction dA and when the dosing motor rotates in the second direction the piston slides in the dispensing direction dD.

[0069] The piston drivetrain is formed of multiple components which engage with each other in order to transfer the rotational force of the dosing motor to a linear motion of the piston along the axis A - A.

[0070] The piston drivetrain comprises a spindle 106 extending along a spindle axis B - B which is driven by the dosing motor 102 such that the spindle rotates around the spindle axis B - B. The spindle axis B - B is parallel to the axis A - A.

[0071] The piston drivetrain further comprises a slide 107. The slide extends transversely to the dosing axis A - A and the spindle axis B - B and intersects both axes.

[0072] A spindle nut 108 is arranged in the slide coaxially with the spindle axis B - B such that the spindle extends through the spindle nut and the slide. The spindle 106 comprises an outer threaded surface 150 which engages with an inner threaded 151 surface of the spindle nut 108. Thus, when the dosing motor rotates the spindle the outer threaded surface of the spindle engages the inner threaded surface of the spindle nut which transforms the rotational motion of the dosing motor to a linear motion of the spindle nut 108 along the spindle axis B - B, and thus also along the dosing axis A - A. Since the spindle nut is arranged and fixed to the slide 107 the slide will also move along the axes A - A and B - B.

[0073] The piston drivetrain further comprises a piston rod 109 attached to the slide 107. The piston rod extends coaxially along the dosing axis A - A to the piston 105. The piston and the piston rod are in the current embodiment different elements, but could be formed as an integral element. A sealing O-ring 110 is arranged around the piston and engages the side of the channel 104 of the cylinder 103, such that an air-tight seal is provided.

[0074] Thus, it is understood that the piston drivetrain comprises the spindle 106, the spindle nut 108, the slide 107 and the piston rod 109 which all engages with each other in order to transfer the rotational motion of the dosing motor 102 to a linear motion of the piston 105.

[0075] Accordingly, during liquid handling, aspiration and dispensing of a sample is done by a pipette tip 111 , which is coupled to the dosing tool. The pipette tip is coupled to the dosing tool via a coupling tip 112. The coupling tip engages the inside of the pipette tip in a secure and sealing manner. The piston drivetrain may then move the piston to a reference position as shown in Fig. 2 such that the dosing tool is in a reference configuration. In its reference position the piston is moved as far toward the distal end 103” of the cylinder 103 as possible. Since the piston can be moved all the way toward the distal end of the cylinder 103 it practically means that any dead volume in the cylinder is removed. The reference position of the piston will typically be the position in which aspiration of a liquid sample into the pipette tip is initiated.

[0076] During aspiration the piston drivetrain may move the piston toward the proximal end 103’ of the cylinder 103. It may move the piston all the way to a maximum stroke position which is shown in Fig. 3 such that the dosing tool is in a maximum stroke configuration. The maximum stroke position is the position the piston will be in when the maximum volume possible for the dosing tool to aspirate is received in the pipette tip. Accordingly, during aspiration and dispensing the piston may be positioned anywhere between the reference position in Fig. 2 and the maximum stroke position in Fig. 3 depending on the amount of liquid which needs to be aspirated and the amount of liquid that should be dispensed.

[0077] When the liquid handling has been performed and the sample has been dispensed from the pipette tip, the pipette tip is ready to be removed from the dosing tool. In the current embodiment this is done by an ejection element in the shape of an ejection sleeve 113 which is arranged coaxially around the cylinder 103 along the axis A - A. The ejection sleeve has an inner circumference at the distal end 113” of the ejection sleeve, which is smaller than the outer circumference of the proximal end 11 T of the pipette tip. Thus, when the ejection sleeve is moved in an ejection direction dE towards the pipette tip, as shown in Fig. 4, the ejection sleeve will engage the pipette tip and disengage the pipette tip from the coupling tip 112 by applying sufficient force to overcome the coupling between the coupling tip and the pipette tip. As can be understood in the present embodiment the ejection direction dE is parallel to the axis A - A and moves in the same direction as the dispensing direction dD.

[0078] In order to move the ejection sleeve the dosing motor 102 is coupled to the ejection sleeve 113 via an ejection drivetrain such that when the dosing motor rotates in the first direction the ejection sleeve moves in the ejection direction dE and when the dosing motor rotates in the second direction the ejection element moves in the opposite direction of the ejection direction.

[0079] The ejection drivetrain is formed of multiple components which engage with each other in order to transfer the rotational force of the dosing motor 102 to a linear motion of the ejection sleeve 113 along the axis A - A.

[0080] The ejection drivetrain shares some of the components of the piston drivetrain. In particular, the spindle 106, the spindle nut 108 and the slide 107 are also used in the ejection drivetrain.

[0081] The ejection drivetrain further comprises an activation push rod 115 which is slidably arranged along axis A - A in the aspiration direction dA between a neutral position as shown in Figs. 1 a, 2, and 3 to an activation position as shown in Fig. 4. A distal end 115” is engaged by the slide 107, whereby the activation push rod 115 is moved to the activation position by slide 107, by moving the slide from the maximum stroke position of the slide and piston in the aspiration direction dA to the activation position.

[0082] As the activation push rod 115 is moved to the activation position a motion deflection device 116 is activated which changes the direction of the motion in the aspiration direction dA to a motion in the ejection direction dE. An ejection push rod 117 extends along an ejection axis C - C, which is parallel to the axis A - A and B - B. A proximal end 117’ of the ejection push rod is coupled to the motion deflection device and a distal end 117” of the ejection push rod is coupled to the ejection sleeve 113. Thus, as the activation push rod is moved to the activation position in the aspiration direction dA the motion deflection device redirects the motion in the ejection direction dE via the ejection push rod to the ejection sleeve which then decouples the pipette tip from the dosing tool as described above. Thus, it is understood that the ejection drivetrain comprises the spindle 106, the spindle nut 108, the slide 107, the activation push rod 115, the motion deflection device 116 and the ejection push rod 117, which all engages with each other in order to transfer the rotational motion of the dosing motor to a linear motion of the ejection sleeve 113.

[0083] As the ejection sleeve engage the pipette tip a force will build up before the tip is ejected. This force build-up will result in an increase of the current required to drive the dosing motor. As the pipette tip decouples the opposite directed force on the ejection sleeve will disappear and the current needed to drive the dosing motor will drop. Thus, by monitoring the current driving the dosing motor it can be determined when the tip has been ejected and the dosing tool can be moved back to the maximum stroke position shown in Fig. 3.

[0084] The motion deflection device 116 shown in the embodiment of Figs. 1 - 4, comprises a gear and rack assembly. A first rack gear 120 is arranged at the proximal end 115’ of the activation push rod 115. A second rack gear 121 is arranged on the proximal end 117’ of the ejection push rod 117. The teeth of the first rack gear and the second rack gear faces towards each other. The first rack gear and the second rack gear engage a gear wheel 122 arranged between the first and second rack gear. The gear wheel 122 is arranged on and rotatably around a gear shaft 123. The gear shaft extends transverse to the axis A - A and perpendicular to a plane containing the axis A - A and the axis C - C.

[0085] Thus, as the first rack gear 121 is moved in the aspiration direction as the activation push rod is moved to the activation position the gear wheel 122 will rotate and engage the second rack gear which will move the ejection push rod 117 in the ejection direction dE as discussed.

[0086] After the ejection action has been performed, i.e. the pipette tip has been decoupled from the dosing tool, the slide and piston are moved in the dispensing direction dD away from the activation position. A first compression spring 125 is arranged around the activation push rod and a second compression spring 126 is arranged around the ejection push rod. As the slide 107 moves away from the activation position in the dispensing direction the first and second compression spring will move the ejection sleeve 113 opposite the ejection direction dE. This allows for a new pipette tip to be arranged on the dosing tool 100. As the slide 107 is moved up and down by the rotation of the spindle 106 an undesired torque may be exerted on the slide such that the slide may have some lateral movement, transverse on the axis A - A instead of a purely linear movement along the axis A - A. Such lateral movement may twist the piston rod and slightly move the piston up or down in the cylinder thereby creating an undesired effect on the dosing action.

[0087] Thus, in order to reduce or even eliminate the effect of the torque on the slide a torque control engagement may be provided. One such torque control engagement may be provided by a slide cylinder in the shape of a hollow shaft 130 fixed to the housing and extending through the slide along the axis C - C. The slide will be able to slide along the hollow shaft along the axis C - C but the hollow shaft will prevent the slide from moving transversely to the axis C - C and thus also the axis A - A.

[0088] Even further, in order to make the design of the dosing tool even more compact the hollow shaft comprises a channel wherein the ejection push rod 117 may extend through from the motion deflection device 116 to the ejection sleeve 113. Thus, the hollow shaft 130 and the ejection push rod 117 extend co-axially along the axis C - C.

[0089] In order to control the dosing tool during liquid handling an electronic circuit 140 is provided.

[0090] The electronic circuit comprises a dosing motor controller 141 which communicates with the dosing motor 102 and controls the operation thereof.

[0091] The electronic circuit further comprises a pressure sensor 142 which monitors the pressure of the air cushion of the variable volume in the cylinder channel 104. A pressure duct 143 connects the cylinder channel and the pressure sensor.

[0092] Furthermore, the electronic circuit comprises a communication module 144 which allows the dosing tool to communicate with a liquid handling system (not shown). The communication module may be a wired connection which provides a fixed communication or it may be a wireless communication.

[0093] Furthermore, the dosing tool 100 comprises a limit switch provided by a magnet 131 extending from the slide 107 and a magnetic field sensor 133. Thus, when the slide 107 is moved close to the magnetic field sensor 133 the sensor will detect the magnet 131 and it can be determined when the slide and the dosing tool is in the reference configuration as shown in Fig. 2.

[0094] The electronic circuit comprises a power control board (PCB) 145 which ensures the electronic control of the different parts, e.g. the dosing motor controller 141 , the pressure sensor 142, the communication module 144 and the magnetic field sensor 133.

[0095] A second embodiment of a dosing tool 200 is shown in part in Fig. 5a in a maximum stroke configuration of the dosing tool, and 5a in an activation configuration of the dosing tool, where a second embodiment of a motion deflection device 216 is provided.

[0096] An activation push rod 215 and an ejection push rod 217 are provided as described in relation to the first embodiment. A lever 250 is rotatably arranged around a lever shaft 251 . A first flange 252 of the lever extends from the lever shaft and engages the proximal end 215’ of the activation push rod 215. A second flange 253 extends from the lever shaft in the opposite direction of the first flange. The second flange engages the proximal end 217’ of the ejection push rod 217.

[0097] Thus, as the activation push rod is moved in the aspiration direction dA (by the slide 207) to the activation position the lever 250 will rotate around the lever shaft and push the ejection push rod in the ejection direction dE whereby the ejection sleeve (not shown) ejects the pipette tip.

[0098] A compression spring 225 is arranged around the activation push rod. This will move the activation push rod away from activation position as the slide 207 is moved in the dispensing direction dD to the maximum stroke position.

[0099] Reference numbers dosing tool 100; 200 pipette tip 1 11 housing 101 dosing motor 102 cylinder 103 channel 104 piston 105 spindle 106 slide 107; 207 spindle nut 108 outer threaded surface 150 inner threaded 151 piston rod 109; 209 sealing O-ring 110 coupling tip 1 12 ejection sleeve 113 activation push rod 1 15; 215 motion deflection device 116; 216 ejection push rod 117; 217 first rack gear 120 second rack gear 121 gear wheel 122 gear shaft 123 first compression spring 125; 225 second compression spring 126 hollow shaft 130; 230 electronic circuit 140 dosing motor controller 141 pressure sensor 142 pressure duct 143 communication module 144 magnet 131 magnetic field sensor 133 power control board (PCB) 145 lever 250 lever shaft 251

Claims

Claims1 . A dosing tool (100; 200) for aspiration and dispensing of a liquid in a removable pipette tip (111 ), wherein the dosing tool (100) comprises an ejection element (113) which decouples the pipette tip (111) from the dosing tool (100; 200) when activated, wherein the dosing tool (100; 200) comprises,- a variable volume defined by a cylinder (103), a piston (105) arranged in the cylinder (103) and a distal end of the cylinder (103”),- a dosing motor (102) coupled to the piston (105), such that the dosing motor (102) drives the piston (105) along an axis A - A within the cylinder (103), such that the piston (105) is driven in either an aspiration direction dA away from the distal end of the cylinder (103”) whereby the variable volume is increased, or in a dispensing direction dD toward the distal end of the cylinder (103”) whereby the variable volume is decreased, and wherein the ejection element (113) is activated when the piston (105) is moved in the aspiration direction to an activation position.

2. A dosing tool (100; 200) according to claim 1 , wherein the dosing tool (100) comprises a housing (101) connected or connectable to a carrier arm in a liquid handling device and wherein the cylinder (103) and the dosing motor (102) are fixed to the housing (101).

3. A dosing tool (100; 200) according to claim 1 or 2, wherein the dosing motor (102) is coupled to the piston (105) via a drivetrain, wherein the drivetrain comprises a slide (107; 207) coupled to the piston (105), wherein the dosing motor (102) drives the slide (107; 207) in either the aspiration direction or in the dispensing direction.

4. A dosing tool (100; 200) according to claim 2 and 3, wherein the slide (107; 207) is arranged in the housing (101) such that the slide (107; 207) is moveable relative to the housing (101 ).

5. A dosing tool (100; 200) according to claim 3 or 4, wherein the drivetrain further comprises a spindle (106) driven by the dosing motor (102), a spindle nut (108) for converting rotational movement into a translational movement along the piston axis A - A, wherein the spindle nut (108) is connected to the slide (107; 207), and a piston rod(109) is coupled to the slide (107; 207) and where the piston rod (109) extend along the axis A - A from the slide (107; 207) to the piston (105) arranged in the cylinder (103).

6. A dosing tool (100; 200) according to claim 5, wherein the distal end of the piston rod (109) provides the piston (105).

7. A dosing tool (100; 200) according to claim 5 or 6, wherein the slide (107; 207) extends transversely to the axis A - A between the spindle (106) and the piston rod (109).

8. A dosing tool (100; 200) according to any one of the claims 3 - 7, wherein at least a first torque control engagement is provided to prevent the slide (107; 207) to move transversely to the axis A - A.

9. A dosing tool (100; 200) according to claim 8, wherein the dosing tool (100; 200) comprises a housing (101) connected or connectable to a carrier arm in a liquid handling device where the slide (107; 207) is arranged in the housing (101 ) such that the slide (107; 207) is moveable relative to the housing (101 ), and wherein the dosing tool (100) further comprises that the first torque control engagement, or an additional torque control engagement, comprises a through-going opening extending through the slide (107; 207) along an axis C - C and the housing (101 ) comprises a slide cylinder (130; 230) extending along the axis C - C where the slide cylinder (130; 230) extend through the through-going opening of the slide (107; 207).

10. A dosing tool (100; 200) according to any one of the preceding claims, wherein a motion deflection device (116; 216) is provided to activate the ejection element (113) when the piston (105) is moved in the aspiration direction to the activation position by deflecting the motion in the aspiration direction toward the ejection element (113) in an ejection direction.11 . A dosing tool (100; 200) according to claim 10, wherein the ejection direction is parallel to the dispensing direction.

12. A dosing tool (100; 200) according to claim 10 or 11 , wherein the motion deflection device (116; 216) comprises a activation push rod (115; 215) which is moveable between a neutral position and an activation position, wherein the activation push rod (115; 215) is moved from the neutral position to the activation position in the aspirationdirection when the piston (105) is moved in the aspiration direction to the activation position.

13. A dosing tool (100; 200) according to claim 10, 11 or 12, wherein the motion deflection device (1 16; 216) comprises an ejection push rod (1 17; 217) engaging the ejection element (113) and where the ejection push rod (117; 217) is moveable between a neutral position and an activation position, wherein the ejection push rod (1 17; 217) is moved from the neutral position to the activation position in the dispensing direction when the piston (105) is moved in the aspiration direction to the activation position.

14. A dosing tool (100; 200) according to claim 9 in combination with claim 13, wherein the ejection push rod (1 17; 217) is arranged slidably along the axis C - C within the slide cylinder (130; 230).

15. A dosing tool (100) according to claim 10 or 11 , wherein the motion deflection device (1 16) comprises,- an activation push rod (115) which is moveable between a neutral position and an activation position, wherein the activation push rod (115) is moved from the neutral position to the activation position in the aspiration direction when the piston (105) is moved in the aspiration direction to the activation position,- an ejection push rod (117) engaging the ejection element (1 13) and where the ejection push rod (117) is moveable between a neutral position and an activation position, wherein the ejection push rod (1 17) is moved from the neutral position to the activation position in the dispensing direction when the piston (105) is moved in the aspiration direction to the activation position, and- a gear assembly for transferring and redirecting motion in the aspiration direction from the activation push (1 15) rod to motion in the dispensing direction in the ejection push rod (1 17).

16. A dosing tool (100) according to claim 15, wherein the gear assembly comprises,- a gear wheel (122) arranged between the activation push rod (1 15) and the ejection push rod (1 17),- an activation gear rack (120) arranged on the activation push rod (115),- an ejection gear rack (121) arranged on the ejection push rod (121 ), and wherein the activation gear rack (120) and the ejection gear rack (121) engage the gear wheel (122).

17. A dosing tool (200) according to claim 10 or 11 , wherein the motion deflection device (216) comprises,- an activation push rod (215) which is moveable between a neutral position and an activation position, wherein the activation push rod (215) is moved from the neutral position to the activation position in the aspiration direction when the piston is moved in the aspiration direction to the activation position,- an ejection push rod (217) engaging the ejection element and where the ejection push rod (217) is moveable between a neutral position and an activation position, wherein the ejection push rod (217) is moved from the neutral position to the activation position in the dispensing direction when the piston is moved in the aspiration direction to the activation position, and- a lever assembly for transferring and redirecting motion in the aspiration direction from the activation push rod (215) to motion in the dispensing direction in the ejection push rod (217).

18. A dosing tool (200) according to claim 17, the lever assembly comprises a lever (250) comprising a first flange (252) and a second flange (253), wherein the lever (250) is arranged rotatably on a hinge axis (251) extending transversely to the axis A - A and between the activation push rod (215) and the ejection push rod (217), wherein the first flange (252) extends from the hinge axis (251 ) toward the activation push rod (215) and the second flange (253) extends from the hinge axis (251) towards the ejection push rod (217), wherein the activation push rod (215) engages the first flange (252) when the activations push rod (215) is moved from the neutral position to the activation position in the aspiration direction and the second flange (253) moves in the opposite direction of the first flange (252), the second flange (253) engages the ejection push rod (217) and moves the ejection push rod (217) from the neutral position to the activation position in the dispensing direction.

19. A dosing tool (100; 200) according to any one of the preceding claims, wherein the ejection element (113) comprises a sleeve part surrounding at least the distal end ofthe cylinder (103) and wherein the sleeve part is slidable relative to the cylinder along the axis A - A.

20. A dosing tool (100; 200) for aspiration and dispensing of a liquid in a removable pipette tip (111 ), wherein the dosing tool (100; 200) comprises an ejection element (1 13) which decouples the pipette tip (1 11 ) from the dosing tool (100; 200) when activated, wherein the dosing tool (100; 200) comprises,- a housing (101 ) connected or connectable to a carrier arm in a liquid handling device,- a dosing motor (102) fixed to the housing,- a slide (107; 207) slidably arranged along an axis A - A relative to the housing (101 ) between an activation position and a reference position,- a drivetrain connecting the dosing motor (102) to the slide (107; 207) for driving the slide (107; 207) in an aspiration direction along the axis A - A towards the activation position or in a dispensing direction in the opposite direction along the axis A - A toward the reference position,- a cylinder (103) fixed to the housing (101 ), the cylinder (103) defines a channel (104) extending between a proximal end of the cylinder (103’) and a distal end of the cylinder (103”),- a piston (105) arranged in the channel (104) of the cylinder, wherein the piston (105) is driven by the slide (107: 207) in the aspiration direction toward the proximal end of the cylinder (103’) or in the dispensing direction toward the distal end of the cylinder (103”),- a coupling arrangement (1 12) for detachably coupling a pipette tip (11 1 ) to the dosing tool (100; 200), where the coupling arrangement (112) is provided at the distal end of the cylinder (103”),- the ejection element (113) arranged at the coupling arrangement (1 12) and moveable into an activation position for decoupling the pipette tip (11 1 ),- a motion deflection device (116; 216) for transferring motion from the slide (107; 207) in the aspiration direction to a motion in the dispensing direction for moving the ejection element (103) into the activation position, and- an ejection push rod (117; 217) for transferring the motion from the motion deflection device (116; 216) to the ejection element (103).

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