EP2848307B1 - Pipette device with a coupling formation for coupling a specially formed pipette tip and with a locking body that can be formed by a magnetic field for locking and unlocking the pipette tip on the coupling formation - Google Patents

Description

The present invention relates to a pipetting device for aspiration and dispensing of liquids, having a coupling formation for coupling a pipetting tip formed separately from the pipetting device thereon, the coupling formation being penetrated by a pipetting channel which extends through the coupling formation along a channel path, in particular a rectilinear channel axis , wherein the coupling formation cooperates with a deformable locking body which is disposed around the pipetting channel and radially between the coupling formation and the pipetting tip in the coupling state in which a pipetting tip is coupled to the coupling formation, the pipetting device further comprising a locking body actuating device is designed and activated to cause a deformation of the locking body, wherein the locking body depends on different Aktivieru Sgszuständen the locking body actuating device relative to the channel track has different radial extension states.

A generic pipetting device is from the WO-A-0062933 known. In the generic pipetting device, a portion of the coupling formation for coupling a pipetting tip is inserted axially into a counter-coupling formation of the pipetting tip. In the coupling state, the negative feedback formation surrounds an axial section of the coupling formation radially outward. At an opposite end of the insertion direction facing the inserted portion of the coupling formation, which end face on the inserted portion in the insertion direction Trailing longitudinal end is formed, lies on an O-ring made of elastomer. This is deformable by a relative to the inserted portion of the coupling formation axially movable squeezing in the axial direction and thus indirectly in the radial direction.

From the generic document also known pipetting tips, which cooperate with the coupling formation of the known pipetting, have on an inner peripheral surface of its negative feedback portion a circumferential radial recess into which the O-ring as the locking body of the coupling formation of the known pipetting device spatially engages when in axial Direction is squeezed by the squeezing.

Due to the axial compression of the O-ring as the known locking body a radial expansion of the same is effected so that it has a larger radial extent in the axially crimped and thus deformed state than in the relaxed, undeformed state.

In the deformed state, the O-ring can engage in the circumferential radial recess on the inner peripheral surface of the negative feedback portion of the pipette tip and thus lock the pipetting tip positively to the coupling formation. By relaxing the O-ring, it comes out of engagement with the recess on the inner peripheral surface of the negative feedback portion of the pipette tip, so that it can be stripped from the coupling formation.

In the known pipetting device, the O-ring must be deformed as a locking body for the entire duration of coupling a pipette tip to the coupling formation, ie during the entire coupling period, the squeezing device must hold the O-ring deformed as the known locking body actuator and energized accordingly become.

Next, a relatively large amount of space-demanding drive of the squeezing device is necessary for axial crushing of the O-ring, such as an electric motor. This must be taken at the pipetting usually away from the coupling formation. DE 197 08 151 A1 shows a pipetting device for releasably attachable pipette tips with a moving device in which a magnet assembly, latch arrangement or spring arrangement releasably holds the decoupling elements in the connecting position.

It is an object of the present invention to develop the generic pipetting further to the effect that the pipette tip compared to the prior art with less energy consumption can be coupled coupled to the coupling formation and that the locking body actuator is structurally less expensive. This object is achieved according to the present invention by a pipetting device of the type mentioned above having the features of the characterizing part of claim 1.

According to the basic idea of the present invention, the locking body can thus be changed in shape by changing a magnetic field acting on it, so that a pipetting tip can be held by means of the locking body on the coupling formation, depending on the strength and / or polarity of the magnetic field acting on the locking body be released from it for release from the coupling formation.

According to the invention, the material which can be changed in shape by changing a magnetic field comprises a polymer which can be brought into a desired shape in a particularly simple manner and which, in addition to its locking function, can also seal an annular gap existing in the coupling state between the coupling formation and the pipetting tip.

In principle, it may further be sufficient if the locking body comprises a material which is form-changeable by magnetic field to a sufficient extent and has further materials next to it. For reasons of ease of manufacture and assembly, however, it is preferred to form the locking body from such a material.

Then, when the locking body comprises a material changeable by changing a magnetic field passing through it, it is sufficient if the locking body actuating device is designed to change a magnetic field passing through the locking body. Since the squeezing device of the generic pipetting device of the prior art has an electromotive drive, which due to the system must have a magnetic field source and further device parts, such as gears and the like, the locking body actuating device of the present invention over the known from the prior art simplified , In the prior art, therefore, the locking body is mechanically deformed with an electromagnet in the electric motor as a power source, in the present invention, however, magnetic.

According to the invention, the material that can be changed in shape by magnetic field is a polymer filled with permanently magnetizable or / and permanently magnetized particles. In the case of such a filled polymer, owing to the polymer matrix it is possible on the one hand to ensure sufficient deformability and, due to the filling with permanently magnetizable or / and permanently magnetized particles, a sufficient shape change response of the material to an external magnetic field. Preferably, the permanent magnetizable and / or permanent magnetized particles are iron carbonyl particles, which are also available in small particle size in the micron range at a reasonable cost. The polymer is polyvinyl acetate or silicone proved to be suitable for filling with permanent magnetizable and / or permanent magnetized particles.

In order to obtain the most homogeneous possible mixture of silicone and permanently magnetizable or / and permanently magnetized particles, it is advantageous if the average particle diameters are small, for example less than 100 μm. The rule here is that a polymer filled with permanently magnetizable or / and permanently magnetized particles can be the more homogeneous the smaller the average particle diameter is. It is therefore preferred that the permanent magnetizable and / or permanent magnetized particles have an average particle diameter in the range from 1 to 30 .mu.m, preferably 1 to 20 .mu.m, particularly preferably 1 to 10 microns. The mean particle diameter can be determined by screening with appropriate mesh sizes.

If the degree of filling of the polymer with permanently magnetizable or / and permanently magnetized particles is too low, the shape change response of the filled polymer may be too low on the change of a magnetic field acting from outside, so that the change in shape achievable by changing the magnetic field of the locking body is insufficient optionally hold a pipetting tip at the coupling formation and release it for release.

On the other hand, if the degree of filling of the polymer is too high, the particles may interfere with each other in mobility, so that a locking body formed of such a material may be too rigid to cause a sufficient strain response under the influence of a change of an external magnetic field.

Tests have shown that useful locking bodies can be obtained if the polymer filled with permanent-magnetizable or / and permanently magnetized particles in the hardened, ready-to-use state is 80 to 60% by weight of permanently magnetizable or / and permanently magnetized Particles and 20 to 40 wt .-% polymer composition. The proportion by weight of permanently magnetizable or / and permanently magnetized particles in the total weight of the material which can be changed by changing the magnetic field is preferably from 67 to 73% by weight, particularly preferably from 70% by weight.

The locking body may be formed in one piece or several pieces, so it may consist of a single or several separate components.

Advantageously, the locking body is a closed ring which, at least in the coupling state, preferably in each state, revolves around the channel path. The locking body as a closed ring or at least a closed ring is a prerequisite that the locking body can not only keep a pipette tip locked to the coupling formation, but also can seal an existing between coupling formation and pipetting tip annular gap.

The locking body can then be sufficiently deformed with a particularly low expenditure of energy if it has a fixing portion designed for its attachment to a structure supporting it and a locking portion extending axially and / or radially from it. In this case, the locking portion is formed by deformation relative to the fixing portion for locking a pipette tip to the coupling formation and for unlocking the same. In the said preferred case, the fixing portion can be made relatively massive and with a large volume of material as compared with the locking portion, so that the fixing portion can be securely received on a structure supporting it. The locking portion projecting from the fixing portion may be formed with thinner cross-sectional dimensions as compared with the fixing portion, so that the deformation thereof requires less causing force than the deformation of the locking portion more massive festiegeabschnitts. For example, the locking portion may be in the form of a lip, in particular a lip which completely surrounds the channel path. Also, the fixing portion may be formed to exercise substantially equal forces along the circumferential direction around the channel path as around the channel track circumferential ring. Particularly preferably, the locking body for this purpose be rotationally symmetrical, in particular with the channel path as the rotational symmetry axis, be formed.

Due to the preferred filling of a polymer matrix with permanently magnetized or / and permanently magnetisable particles, it may happen that particles are exposed at the outer surface of the locking body, in particular the locking section, which is exposed to the atmosphere. Here, on the one hand, there is the risk that these edge particles will be released from the polymer matrix over time by the magnetic field acting on the locking body and the associated changing deformation, leaving a recess in the locking body. As a result, on the one hand, the deformability of the locking body can be reduced by a given magnetic field and, on the other hand, its suitability for sealing an annular gap existing in the coupling state between the coupling formation and the pipetting tip can be reduced. It is therefore preferred that at least one outer surface exposed to the atmosphere, particularly preferably the outer surface, of the locking body has a closed polymer skin. A condition in which a pipetting tip to be coupled is completely detached from the coupling formation and in which the locking body has a shape in which it is possible to attach the pipetting tip to the coupling formation and to strip it from the latter is decisive for the assessment of an exposure to the atmosphere is. This means that the locking body protrudes in this state radially less far from the structure carrying it before in the coupling state.

Since the lock body actuator for changing an on The locking body actuating device preferably comprises a magnet, said magnetic field acting on or passing through the locking body. This is preferably rotationally symmetrical with respect to the channel path to always be able to generate a substantially rotationally symmetrical magnetic field and thus a substantially rotationally symmetrical force along a circumferential direction around the channel path as the axis of rotational symmetry.

The magnet is for changing a locking body passing through, d. H. formed on this acting, magnetic field to realize different activation states of the locking body actuator. The training for changing the magnetic field, for example, in a permanent magnet by its displaceability to the locking body out and away from it, so that said magnet may be a relative to the channel path, preferably along the same, displaceable magnet. However, since a movement drive for the magnet is needed here, this realization of the lock body actuator is less preferred. On the other hand, it is more preferable to use an electromagnet than the above-mentioned magnet, which can generate a changing magnetic field by different energization and therefore can be provided non-storable.

To change the activation state of the locking body actuating device, the pipetting device may further comprise a control device which cooperates with the locking body actuating device for changing the locking body passing through, ie acting on it, magnetic field and thus just to change the activation state of the locking body actuator. In the above-mentioned preferred case of using an electromagnet, the control device may be configured to change the current intensity of the current flowing through the electromagnet.

A simple, compact coupling formation, which does not differ in its dimensions from the existing coupling formations of the prior art, can be obtained by providing a conductor coil of the electromagnet in the coupling formation surrounding the pipetting channel. The pipetting channel is thus not disturbed by the conductor coil of the electromagnet. The coupling formation, which usually has at least one cylindrical and / or conical section, is excellently suited, due to its shape, to receive a conductor coil of an electromagnet. Preferably, a virtual winding axis of the conductor coil or / and a cylinder axis or cone axis of the cylindrical or / and conical section coincides with the channel track, in particular the channel axis.

The outgoing from the conductor coil of the electromagnet magnetic field can be guided and amplified that the conductor coil of the electromagnet - with respect to the channel path - at least one axial axial ends of a ferromagnetic yoke leg is axially opposite. This effect is even greater when the conductor coil axially opposite at each axial longitudinal ends of a ferromagnetic yoke leg so that the conductor coil is located axially between the two yoke legs.

Further guidance and amplification of the magnetic field emanating from the conductor coil of the electromagnet can be achieved by radially opposing a yoke base in radial direction to a conductor coil of the electromagnet, preferably radially nearer to the channel path. In this case, the yoke base can be used as a winding support of the conductor coil, which facilitates the mounting of the electromagnet and the yoke base on the pipetting device.

Likewise, a radial end of the yoke base facing away from the conductor coil can form a wall radially delimiting the pipetting channel in the coupling formation. In a particularly preferred case, thus, the yoke base both serve as a winding carrier, such as with a coil wound radially outward on her, as well as define a yoke passing through the pipetting channel.

To reduce the installation effort and to avoid air gaps between the yoke base and yoke legs can be provided that the yoke base and the yoke leg, preferably the yoke base and both yoke legs, are integrally formed.

At least one yoke limb, preferably both yoke limbs, and / or the yoke base can be rotationally symmetrical in order to provide a magnetic field which is as rotationally symmetrical as possible. In this case, the channel path is preferably the rotational symmetry axis.

In order to allow the magnetic field guided and amplified by one or more yoke legs to act on the locking body as effectively as possible, it can be provided that a radial end face of a yoke leg pointing radially outwards extends over an axial extension area, the locking body extending in this axial extent area End face, but located radially outside of it. For the best possible enforcement of the locking body with the magnetic field emanating from the end face, it is preferred that the material of the locking body, which is changeable by changing the magnetic field, adjoins the end face radially directly, particularly preferably without any air gaps.

When, as stated above, at least two yoke legs are provided axially spaced from each other, each having a radially outwardly facing radial end surface extending over an axial extension region, the locking force achievable by the locking body can be increased by locking the locking body a plurality of partial locking bodies, each of which partial locking body in the axial extension region of another radial End surface of the plurality of radial end surfaces, but located radially outside thereof. Preferably, the locking body comprises as many part-locking body as radial end surfaces of axially spaced yoke legs are provided. For the reasons mentioned above, it is again preferred that the magnetically deformable material of each partial locking body adjoins the end face radially directly, particularly preferably free of air gaps, in the axial extent of which the partial locking body is located.

Preferably, each partial locking body, or in the case of only one locking body, is just that, only in the axial extension region exactly one radial end surface of a yoke leg. It should not be ruled out that the locking body or the partial locking body, axially has a smaller or larger extent than the respectively associated radially outwardly facing radial end surface of a yoke leg. However, preferably only one such end face is associated with a partial latch body, i. H. the radial extension region of the partial locking body overlaps or overlaps only with the radial extension region of an end surface of a yoke leg.

In order for the locking body when it is provided on the coupling formation to be able to provide a retreat, in which this radially inward, ie towards the channel path back, so as to unlock a coupling tip coupled to the coupling formation and release for releasing , Preferably, the yoke leg is formed radially shorter than the coupling formation in which the yoke leg is received. In the event that a plurality of yoke legs are provided, at least one leg, but are preferably all yoke legs, radially formed shorter than the coupling formation receiving them.

A particularly effective deformation of the locking body, in particular if this as described above with a fixing section and a protruding therefrom locking portion can be achieved, that a conductor coil of the electromagnet radially inward, opposite to both axial sides and radially outwardly a ferromagnetic yoke, wherein the ferromagnetic yoke in the electromagnet radially outside and / or axially opposite region having the yoke interrupting gap, in which the locking body is arranged. The locking body can be accommodated in the gap in such a way that it closes the gap at a certain energizing state of the electromagnet, ie supplements the ferromagnetic yoke to a yoke completely surrounding the electromagnet orthogonal to its winding direction and does not bridge the gap interrupting the yoke to a predetermined other energizing state , that is not enough from one column end to the other column end of the yoke. Likewise, the locking body may be provided in the predetermined other Bestromungszustand with an air gap to both the yoke gap bounding surfaces. For reasons of the most effective utilization of the magnetic field occurring at the yoke gap, however, it is preferred if the locking body is provided free of air gap on one of the gap delimiting yoke portions and is provided in a predetermined Bestromungszustand to form a gap at a distance from the other of the other gap limiting yoke portion ,

In this case, the enforcement of the locking body is secured with the prevailing in the yoke gap depending on Bestromungszustand of the electromagnet magnetic field. For this constructive embodiment is provided in particular that the locking body in a predetermined further Bestromungszustand at both the yoke gap bounding yoke portions is free of air gap.

The coupling formation usually has an insertion end, which is the axial longitudinal end of the coupling formation, which, when a pipetting tip is coupled to the coupling formation in a plug-in direction, is inserted first into a counter coupling formation of the pipetting tip becomes. Accordingly, when the pipetting tip is released from the coupling formation, the insertion end of the coupling formation leaves the counter-coupling formation of the pipetting tip last.

Then, the coupling formation may be formed such that an insertion end of the coupling formation closer portion of a yoke portion which is opposite to the electromagnet radially outwardly formed radially thicker than the insertion end remote from the yoke portion. The radially thicker yoke portion thus forms a larger diameter portion, behind which the locking body can be radially deformed back depending on the activation state of the locking body actuator to unlock the pipetting tip for release from the coupling formation. Likewise, the locking body may be deformed radially beyond the thicker yoke portion to lock the pipetting tip to the coupling formation.

Again, the two regions of the yoke portion of different radial thickness may be separated by a gap. It may be the gap already described above. Preferably, the locking body is arranged in the gap. In order to enable unlocking of the pipette tip, ie a radial deformation of the locking body behind the radially thicker yoke portion, preferably an outer surface portion of the insertion end of the coupling formation further lying radially thinner yoke portion is formed as a contact surface portion for temporarily abutment of a portion of the locking body. Preferably, the region of the locking body reaching into the abutment surface section in a temporary abutment is the abovementioned locking section protruding from the securing section. The temporary application of a region of the locking body on the abutment surface portion takes place in dependence on the activation states of the locking body actuating device, in particular of the energization states of the electromagnet.

Preferably, the lock body in the de-energized state of the electromagnet on the form which it assumes or assumes in the coupling state.

In order to be able to enforce the locking body as safely and effectively as possible with the magnetic field that can be generated in the yoke gap, the locking body can be provided on an outer surface area of the radially thicker yoke portion independently of the activation state of the locking body actuating device. Since the radially thicker yoke section is formed on the region of a yoke section closer to the insertion end, the yoke gap on the side of the radially thicker yoke section is generally delimited by a free strin surface pointing in the axial direction, which is a particularly advantageous possibility of the air gap-free arrangement of the locking body offers to her.

A desired shape that the lock body or a portion thereof occupies in a predetermined activation state of the lock body operating device may be modeled by a support body to which the lock body is supported to varying degrees depending on activation states of the lock body operation device. In this case, a support by surface abutment of the locking body or a portion thereof on the support body is preferred because this reduces the force exerted in the support state of the support body on the locking body load area. Preferably, the support body is a support ring, which rotates closed around the channel path in the same way as the preferably designed as a closed ring locking body. Thus, according to a development of the present invention, a support body, preferably in the form of a support ring, is provided radially between the coupling formation and a portion of the locking body. The radial dimension of the support body, in particular of the support ring, can change in the axial direction to a desired to the designed for temporary abutment against the support body portion of the locking body during its abutment against the support body Shape up the shape. Preferably, the radial dimension of the support body with progression in the axial direction increases from an end of the support body which is closer to the insertion end of the coupling formation to a end which is farther toward this end.

The magnet may comprise as electromagnet a plurality of conductor coils, in particular exactly two conductor coils. These conductor coils can be provided at an axial distance from each other, wherein the locking body can be arranged axially between two axially spaced apart conductor coils. The locking body is preferably arranged between two directly axially adjacent conductor coils. In this case, the interlocking body can be surely penetrated by the magnetic field emanating from two or more conductor coils, which increases the strain work achievable on the interlocking body, so that the same interlocking body deforms more, and in particular changes its radial dimension more in response to the said magnetic field than if only a conductor coil would be present.

In order to be able to couple any commercially available pipetting tips to the further developed pipetting device discussed here, it is preferred if the locking body is provided on the coupling formation, preferably in a radial groove of the same. The radial groove preferably circumferentially revolves around the channel path to provide an annular latch body receiving space. Since the locking body on the coupling formation is generally intended to frictionally engage the coupling formation in the coupling state in the coupling state of a pipetting tip, the radial groove is preferably formed on a radially outer jacket surface of the coupling formation.

1. a.) einen zur Kanalbahn hin vorstehenden Radialvorsprung der Pipettierspitze hintergreifen oder
2. b.) sich in eine Radialausnehmung der Pipettierspitze hinein erstrecken, welche von der Kanalachse radial weg verläuft.

For particularly secure coupling of a pipette tip to the pipetting device, this can be designed accordingly. For this purpose, the pipetting device may comprise a pipetting tip and the locking body in the coupling state

1. a.) engage behind a groove projecting towards the channel path radial projection of the pipette tip or
2. b.) extend into a radial recess of the pipette tip, which extends radially away from the channel axis.

In these cases, in addition to the frictional force always acting between it and the pipetting tip in the event of a contact with the pipetting tip, the locking body can also bring about a positive engagement with the pipetting tip.

Furthermore, it should not be ruled out that the locking body is provided on the pipette tip. For this purpose, the pipetting device may comprise a pipetting tip, with which the locking body is firmly connected. Since, in the coupling state, at least one axial section of the coupling formation is surrounded by a negative feedback formation of the pipetting tip radially outward, the arrangement of the locking element on the negative feedback formation of the pipetting tip is preferred. Here, in turn, the locking body is preferably arranged on an inner surface of the negative feedback formation facing radially inward in the coupling state towards the coupling formation.

In the present application, the penetration of the locking body with a magnetic field is used synonymous with an action of the magnetic field on the locking body.

In the case of pipetting devices, said pipetting channel usually extends from the coupling formation into the pipetting device. For the present application, however, only the portion of the pipetting channel located in the coupling formation should be of interest. This generally follows a channel path, which may have any shape, but for manufacturing reasons, preferably be designed as a straight line channel axis. The coupling formation, which is usually a has cylindrical or / and frusto-conical shape, preferably has the characteristic in their rectilinear shape as the channel axis channel path as a cylinder or cone axis.

Fig. 1a

eine erste Ausführungsform einer erfindungsgemäßen Pipettiervorrichtung mit an ihrer Kopplungsformation angekoppelter und verriegelter Pipettierspitze,

Fig. 1b

die Pipettiervorrichtung von Fig. 1a mit entriegelter Pipettierspitze,

Fig. 2a

eine zweite Ausführungsform einer erfindungsgemäßen Pipettiervorrichtung mit an ihrer Kopplungsformation angekoppelter und verriegelter Pipettierspitze, und

Fig. 2b

die zweite Ausführungsform von Fig. 2a mit entriegelter Pipettierspitze,

Fig. 3a

eine dritte Ausführungsform einer erfindungsgemäßen Pipettiervorrichtung mit an ihrer Kopplungsformation angekoppelter und verriegelter Pipettierspitze,

Fig. 3b

die dritte Ausführungsform von Fig. 3a mit entriegelter Pipettierspitze,

Fig. 4a

eine vierte Ausführungsform einer erfindungsgemäßen Pipettiervorrichtung mit an ihrer Kopplungsformation angekoppelter und verriegelter Pipettierspitze,

Fig. 4b

die vierte Ausführungsform von Fig. 4a mit entriegelter Pipettierspitze,

Fig. 5a

eine fünfte Ausführungsform einer erfindungsgemäßen Pipettiervorrichtung mit an ihrer Kopplungsformation verriegelter Pipettierspitze und

Fig. 5b

die fünfte Ausführungsform von Fig. 4a mit entriegelter Pipettierspitze während ihres Lösens von der Kopplungsformation.

The present invention will be explained in more detail with reference to the accompanying drawings. It shows:

Fig. 1a

A first embodiment of a pipetting device according to the invention with coupled to its coupling formation and locked pipette tip,

Fig. 1b

the pipetting device of Fig. 1a with unlocked pipette tip,

Fig. 2a

a second embodiment of a pipetting device according to the invention with coupled to its coupling formation and locked pipette tip, and

Fig. 2b

the second embodiment of Fig. 2a with unlocked pipette tip,

Fig. 3a

A third embodiment of a pipetting device according to the invention with coupled to its coupling formation and locked pipette tip,

Fig. 3b

the third embodiment of Fig. 3a with unlocked pipette tip,

Fig. 4a

A fourth embodiment of a pipetting device according to the invention with coupled to its coupling formation and locked pipette tip,

Fig. 4b

the fourth embodiment of Fig. 4a with unlocked pipette tip,

Fig. 5a

a fifth embodiment of a pipetting device according to the invention with at its coupling formation locked pipette tip and

Fig. 5b

the fifth embodiment of Fig. 4a with unlocked pipette tip during its release from the coupling formation.

In Fig. 1a a first embodiment of a pipetting device according to the invention in the relevant section of the coupling engagement of a coupling formation of the pipetting device is shown with a negative feedback formation of a pipette tip.

The first embodiment of the pipetting device according to the invention is shown in FIG Fig. 1a generally designated 10. The pipetting device 10 comprises at its coupling-side longitudinal end a coupling formation 12, which is penetrated by a pipetting channel 14. The pipetting channel 14 generally extends along a channel path 16 through the coupling formation 12. This can basically have any, even curved course, but is preferably made for obvious reasons simple production and assembly as a rectilinear channel axis 16.

Unless otherwise stated in this application in an individual case, the channel axis or channel path should in principle define an axial direction and orthogonal starting from it, a radial direction for the description of the present application. As far as a circumferential direction is referred to in the present application, this refers to a circumferential direction around the channel axis.

The free axial longitudinal end 12a of the coupling formation 12, which is in the in Fig. 1a is shown plugged into a pipetting tip 18 is referred to in the present application as "insertion end". The axially opposite longitudinal end 12b is referred to as "device side Longitudinal end ".

The pipetting channel 14 continues axially beyond the device-side longitudinal end 12b of the coupling formation 12, for example into a cylinder 20 of the pipetting device 10. At these a pressure change device 22 is connected in a manner not of further interest here. This may be a piston-cylinder arrangement in the cylinder 20 or a rotating pump. The pressure change device 22 can be controlled via a control device 24. By means of the pressure-changing device 22, the pressure of a working fluid in the pipetting channel 14 can be increased or decreased with respect to the ambient pressure, whereby aspiration or dispensing of liquid into or out of the pipette tip 18 can take place in a manner known per se.

From the pipette tip 18 is in Fig. 1a essentially a negative feedback formation 26 is shown, which in the in Fig. 1a Coupling state shown surrounding an axial portion of the coupling formation 12 radially outward.

The coupling formation 12 may have, in the region of its device-side longitudinal end 12b, a radial projection 12c against which the coupling-side longitudinal end 18a of the pipette tip 18 abuts in the coupling state in order to define the axial position of the pipetting tip 18 relative to the coupling formation 12.

The coupling formation 12 has an immersion section 12d, which is immersed axially in the coupling state in the pipetting tip 18 and is surrounded by the negative feedback formation 26 of the pipetting tip 18 radially outward. In the example illustrated, the immersion section 12d extends axially from the contact surface of the radial projection 12c facing the pipette tip 18 to the insertion end 12a. The immersion portion has a cylindrical or / and conical lateral surface, for example a cylindrical or steep-conical lateral surface portion 12d1 and a flat conical Lateral surface portion 12d2, which also serves as an insertion aid cone for inserting the insertion end 12a into the receiving space of the pipetting tip 18 surrounded by the negative feedback formation 26.

The cylindrical or steep-conical lateral surface portion 12d1 lies flat in the coupling state to an inner surface 18b of the counter-coupling formation 26 of the pipette tip 18 which points in the coupling state to the channel path 16. A steep-conical formation of the lateral surface portion 12d1 of the coupling formation 12 and a corresponding negative-conical configuration of the inner wall 18b of the pipette tip 18 are preferred because this conical coupling and counter-coupling formation facilitates detachment of the pipette tip 18 from the coupling formation 12 in the axial direction.

At the immersion portion 12d of the coupling formation 12, a magnet 28 is accommodated, which in the example shown has two guide coils 28a and 28b arranged axially spaced from one another. The conductor coils, which may also be more than two conductor coils, can be surrounded on their sides by a securing on three sides, ie radially inward and on both axial sides of the material of the coupling formation 12. Radially outside, the conductor coils 28a and 28b can be exposed, thus forming part of the lateral surface portion 12d1.

The conductor coils 28a and 28b each extend around the channel track 16, the winding plane of which runs approximately orthogonally to the channel track or channel axis 16.

The conductor coils 28a and 28b are connected to the control device 24 via a power supply line, so that the conductor coils 28a and 28b can be energized by control with the control device 24. The energization state of the conductor coils 28a and 28b is consequently variable by the control device 24. Thus, the magnetic field emanating from the conductor coils 28a and 28b is in the case of a corresponding current supply changeable and even switched off by switching off an energization of the conductor coils 28a and 28b.

Axially between the conductor coils 28a and 28b, a preferably annularly formed locking body 30 is arranged. This is preferably received in a circumferentially around the channel track 16 circumferential radial groove 32 in the coupling formation.

Locking body 30 is formed from a polymer filled with iron carbonyl particles which is filled with the iron carbonyl particles having a fill level of about 70% by weight of iron carbonyl particles and 30% by weight of polymer mass (when viewed in the cured state) by the conductor coils 28a and 28b outgoing magnetic field is changeable form.

Preferably, the locking body is designed according to an advantageous development of the present invention such that it locks the pipetting tip on the coupling formation without the influence of an external magnetic field, be it by positive locking and / or by frictional engagement, and that it is deformed under the influence of an external magnetic field such in that it releases the pipette tip for release from the coupling formation.

This has the advantage that the magnet 28 only needs to be energized for the short period of time of loosening of the pipetting tip 18 from or for an attachment of the pipetting tip to the coupling formation 12 and can otherwise be left de-energized. The magnet 28 thus constitutes a locking body actuating device in the sense of the present application.

Consequently, the locking body 30 is in Fig. 1a in its shape unaffected by an external magnetic field. The conductor coils 28a and 28b are thus not energized and they do not emit a magnetic field from them.

In this position or operating situation, a radially outer portion 30a of the locking body 30 engage in a circumferential annular groove 34 in the inner surface 18b, so that the pipetting tip 18 is positively held by the locking body 30 to the coupling formation 12.

In Fig. 1a the provided in the pipette tip 18 annular groove 34 is shown with V-shaped cross-sectional profile in positive engagement with the locking body 30.

Notwithstanding this, the circumferential annular groove 34 of the pipette tip 18 may have a contour in which only the flank of the groove 34 located closer to the longitudinal end 18a in the in Fig. 1a illustrated manner is inclined while the axially opposite, the in Fig. 1a Not shown pipetting nearer edge oriented orthogonal to the channel path 16 and / or axially so far away from the beveled edge that the locking body 30 does not come into contact with this. In this case, the radially outer portion 30a of the locking body 30 can come into contact contact exclusively with the inclined surface of the annular groove 34, so that in addition to the positive engagement, the pipette tip 18 can be biased by the locking body 30 against the radial projection 12c of the coupling formation 12, which is a unique axial position the pipette tip 18 is ensured relative to the coupling formation 12 and thus relative to the pipetting device 10.

Instead of a beveled flank, the flank of the annular groove 34 closer to the longitudinal end 18a can also be curved convexly or concavely or can be polygonal in cross-section, as long as only the contact with the locking body 30 causes an axial force to the radial projection 12c of the coupling formation 12.

In Fig. 1b in which the cylinder 20, the pressure change device 22 and the control device 24 are not shown, is the coupling formation 12 of Fig. 1a shown with attached pipette tip 18, now the magnet 28, so the two conductor coils 28a and 28b, are energized and the magnetic field emanating from them acts on the locking body 30, so this enforced.

Under the action of the magnetic field emanating from the magnet 28, the locking body 30 is compared with that in FIG Fig. 1a shown radially contracted shape and axially expanded.

In Fig. 1b the pipetting tip 18 is still attached to the coupling formation 12, so that the negative feedback formation 26 of the pipetting tip 18 still surrounds the immersion section 12b radially outward.

However, due to the energization of the magnet 28 and the resulting magnetic field acting on the locking body 30, the radially outer portion 30a of the locking body is retracted radially into the open radial groove 32 of the coupling formation 12 so that there is no positive engagement between the locking body 30 and the pipetting tip 18 longer exists. An alternatively or additionally existing in the coupling state Reibschlusseingriff is reduced or canceled. In this state, the pipette tip 18 is unlocked and can be stripped axially from the coupling formation 12 or falls axially with a corresponding inclination of the lateral surface portion 12 d1 due to their gravity from the coupling formation 12.

For reasons of a safe release of the pipette tip 18 of the coupling formation 12, the pipetting device 10, however, a known per se and in the Fig. 1a and 1b Scraper device not shown for axially stripping the pipette tip 18 of the coupling formation 12 have.

As soon as the energization of the magnet 28 in Fig. 1b ends, the locking body 30 takes back in Fig. 1a shown position and shape. Instead of switching off and turning on the energization of the magnet 28 different activation states of the magnet can also be achieved by reversing the same or / and by changing the current of the current flowing through it, but due to the associated higher cost (the magnet must then also in the operating state the Fig. 1a energized) is less preferred.

In the Fig. 2a and 2 B A second embodiment of the present invention is shown, which will be described below only insofar as it differs from the first embodiment described above.

Same and functionally identical components and component sections as in the first embodiment of Fig. 1a and 1b are in the Fig. 2a and 2 B denoted by the same reference numerals but increased by the number 100. If the Fig. 2a and 2 B are not expressly described, is to explain their explicit reference to the description of Fig. 1a and 1b directed.

The second embodiment of the Fig. 2a and 2 B has an electromagnet 128 with only a single conductor coil, which as in Fig. 1a shown with one in the Fig. 2a and 2 B not shown in detail is coupled energy transfer moderately.

The electromagnet 128 is surrounded at its two axial sides and radially inwardly by a ferromagnetic yoke 140. The yoke 140 is preferably formed integrally from ferromagnetic material and comprises the yoke legs 140a and 140b and the yoke legs 140a and 140b axially connecting yoke base 140c. The yoke 140 is preferably rotationally symmetrical with respect to the channel axis 116 as an axis of symmetry and simultaneously serves as a winding body for the conductor coil of the electromagnet 128. A radially inner wall of the Yoke 140b forms a wall of pipetting channel 114. However, this need not be so. Instead, the pipetting channel 114 may be completely defined by material of the coupling device 112 which can axially penetrate the yoke 140.

Preferably, the electromagnet 128 is surrounded radially on the outside by a ferromagnetic yoke ring 140d, so that the electromagnet 128 is surrounded on all sides by ferromagnetic yoke material.

However, the yoke 140 has between the yoke ring 140d and each of the two yoke legs 140a and 140b about the channel axis 116 encircling yoke gaps 132 ₁ and 132 ₂ , in which the locking body is arranged as a partial locking body 130 ₁ and 130 ₂ .

More specifically, the insertion latching end 112a of the coupling formation 112 closer partial locking body 130 _{1 is located} in the insertion end 112a closer yoke gap 132 ₁ . Accordingly, the spigot 112 a further preferred partial locking body is located 1302 in the spigot 112a also located further yoke gap 132. ₂

More precisely, each partial locking body 130 ₁ and 1302 preferably closes air gap free to a radially outwardly facing radial end surface 140a1 or 140a2 of the respective yoke gap 132 ₁ and 132 ₂ radially inwardly limiting yoke leg 140a for the best possible coupling to the magnetic field generated by the electromagnet 128 or 140b.

Again shows Fig. 2a In this state, the partial locking bodies 130 ₁ and 1302 protrude radially beyond the lateral surface portion 112d1 of the immersion portion 112d of the coupling formation 112 and form-fit into negative feedback formation 126 of the pipetting apparatus 118 by penetrating the grooves 134a and 134b for sure.

In the in Fig. 2b shown energized state of the electromagnet 128 are the part-locking body 130 ₁ and 130 ₂ with respect to the state of Fig. 2a radially compressed and axially expanded. In this state, the yoke gaps 132 ₁ and 132 _{2 are} preferably completely or at least largely filled by the respective associated partial locking bodies 130 ₁ and 130 ₂ .

Preferably, in the in Fig. 2b shown activation state of energization of the electromagnet 128, the partial locking bodies 130 ₁ and 130 ₂ radially withdrawn behind the outer diameter of the immersion portion 112 d of the coupling formation 112, so that the pipette tip 118 is unlocked for release from the coupling formation 112 and can be axially stripped off this or even can fall off axially.

In the Fig. 3a and 3b A third embodiment of the present invention is shown. This embodiment is described below only insofar as it differs from the first two, to the description of which otherwise expressly referred.

The same and identical components and component sections as in the first embodiment are provided in the third embodiment with the same reference numerals, but increased by the number 200. The same applies to the reference numerals of the second embodiment. These are only increased by the number 100 in the third embodiment.

The third embodiment, like the first, has only one locking body 230. This is arranged in a yoke gap 232 of the yoke 240. The yoke gap 232 again runs around the channel axis 216.

The yoke 240 is formed in two parts as in the second embodiment, wherein the separation of the different yoke components is different than in the second embodiment.

The radially inner yoke base 240c and the yoke leg 240b further away from the insertion end 212a form a common yoke component. Likewise, the yoke leg 240a closer to the insertion end 212a and a yoke portion 240d1 surrounding the electromagnet 228 radially outside form an integral further yoke component.

At the radially outer end of the yoke leg 240b, another yoke portion 240d2 surrounding the electromagnet 228 radially outwardly may be formed. The parting plane between the yoke sections or yoke legs can also be different than in the Fig. 3a and 3b shown. For example, there may be a separation gap between each yoke leg and a yoke portion adjacent thereto, such as the yoke base.

The radially outer yoke portion 240d1 closer to the insertion end 212a is formed radially thicker than the radially outer yoke portion 240d2 farther from the insertion end 212a, preferably with the yoke portion 240d1 forming the largest diameter of the coupling formation 212 such that the negative coupling portion 226 of the pipetting tip 218 in the in-dash the Fig. 3a and 3b shown coupling state preferably in contact only with the lateral surface 212d1 of the yoke portion 240d1 stands.

The locking portion 230 has in the third embodiment, a fixing portion 231, with which it is preferably arranged on an axially facing end face 241 of the radially thicker, the insertion end 212a closer yoke portion 240d1 free of air gap.

From this fixing portion 231 of the locking body 230 projects from a locking portion 233, which is deformable by the magnetic field generated by the electromagnet 228.

In Fig. 3a an activation state of the electromagnet 228 is shown, in which this is preferably energized. The locking body 230 is with its locking portion 233 in form-locking engagement with the annular groove 234 on the inner wall 218 b of the negative feedback portion 226 of the pipette tip 218th

The locking body 230 is dimensioned for reasons of ease of deformability so that it is arranged in the yoke gap 232 that at least in the in Fig. 3a shown de-energized activation state of the electromagnet 228 is a gap 242 between the locking body 230 and the axial direction of the insertion end 212a facing end face of the radially thinner yoke portion 240d2.

In the in Fig. 3b shown activation state of energization of the electromagnet 228 is the locking portion 233, which was previously in positive engagement with the annular groove 234 of the pipette tip 218, on the radially outer lateral surface portion 244 of the yoke 240d2. By this arrangement, the locking body 230, more precisely locking portion 233, is completely retracted from the annular groove 234, so that the pipetting tip 218, as in FIG Fig. 3b is shown, is axially strippable from the coupling formation 212 or even gravity driven from this can fall off axially.

Due to the radial differences in thickness of the yoke sections 240d1 and 240d2, sufficient deformation path is provided for the locking body to completely release the groove 234 of the pipetting tip 218.

In the Fig. 4a and 4b A fourth embodiment of the present invention is shown, which will be described below only insofar as it differs from the preceding embodiments, the description of which is otherwise also referred to the explanation of the fourth embodiment.

The same and functionally identical components and component sections of the first, second and third embodiments are in the fourth embodiment with provided with the same reference numerals, but increased by the number 300, 200 and 100, respectively.

The fourth embodiment is essentially a modification of the third embodiment.

The fourth embodiment substantially corresponds to the third embodiment, wherein the yoke 340 is shown in one piece, for example as a forged part.

The lock body 330 has a different shape than the lock body 230 of the third embodiment. Again, this has a fixing portion 331, which is preferably free of air gaps connected to an axially facing away from the insertion end 312a end face of the radially thicker yoke portion 340d1. From this fixing portion 331, the locking portion 333 protrudes.

Again in is Fig. 4a a state of the pipetting device 310 is shown with the energized activation state of the electromagnet 328, while in Fig. 4b an energization state of energizing the electromagnet 328 is shown.

The essential difference between the fourth embodiment and the third embodiment presented before is a support body in the form of a circumferential about the Pipettierkanalachse 316 support ring 346, which is on a portion of the locking body 330 in abutment. The surface of the support ring 346 contacting the latch body 330 may be fixedly connected to the latch body 330, such as by gluing. However, this does not have to be the case. The support ring may be made of non-magnetizable, permanently magnetisable or even permanently magnetized material. However, since it has only shape modeling function, it can also be inexpensively formed from advantageously non-magnetizable plastic.

In the in the Fig. 4a and 4b In the fourth embodiment shown, the support ring has a radial thickness increasing away from the insertion end 312a. The support ring 346 is designed in such a way that it projects radially increasingly from the pipetting channel axis 316 with increasing distance from the insertion end 312a.

By energizing the electromagnet 328, the locking portion 333 of the locking body 330 is attracted to the radially outer surface 344 of the yoke portion 340d2, so that the locking portion 333 is completely deformed out of the circumferential annular groove 334 of the pipetting tip 318 and the pipetting tip 318 for axially stripping off or falling off the coupling formation 312 is enabled. In the in Fig. 4b shown activation state of energization of the electromagnet 328 surrounds the locking body 330 partially the support ring 346 in the axial and radial directions.

As in the third embodiment, also in the fourth embodiment, in the fourth embodiment, in the activated state of energization of the electromagnet 328, the lock body 330 bridges the yoke gap 332 in which it is disposed completely, that is, in the fourth embodiment. H. the locking body 230 or 330 then extends from the yoke gap 232 or 332 bounding yoke portion 240d1 and 340d1 to the other yoke gap 232 and 332 delimiting yoke portion 240d2 and 340d2.

In the Fig. 5a and 5b a fifth embodiment is shown in which the locking body is provided on the pipetting tip and fixedly connected thereto.

The fifth embodiment will be described below only insofar as it differs from the preceding embodiments 1 to 4, whose description is otherwise expressly referenced. Same and functionally identical components and component sections as in the embodiments 1 to 4 are provided in the fifth embodiment with the same reference numerals, but increased by the number 400, 300, 200 and 100, respectively.

The fifth embodiment has, like the second embodiment, two partial locking bodies 430 ₁ and 430 ₂ . These are essentially identical. Each of the sub-locking bodies 430 ₁ and 4302 has a fixing portion 431 ₁ and 431 ₂ fixedly connected to the pipetting tip 418, from which a locking portion 433 ₁ and 433 ₂ projects. In the in Fig. 5a shown activation state of a de-energized electromagnet 428, the locking portions 433 ₁ and 433 ₂ radially inward and in the axial direction of the insertion end 412a away from the fixing portion 431 ₁ and 431 ₂ from.

In contrast to the previously described embodiments, the electromagnet 428 surrounds the pipetting tip 418 coupled to the coupling formation 412 radially outward. However, this does not have to be the case. The electromagnet 428 may also be provided in the section of the coupling formation 412 projecting into the pipette tip 418, as is the case in the previously described embodiments 1 to 4.

In Fig. 5a the pipetting tip 418 is held by friction engagement of the respective locking sections 433 ₁ and 4332 with the lateral surface of the part of the coupling formation 412 protruding into the pipette tip 418 on the pipetting device exclusively by frictional engagement. This is just an example. The locking sections 433 ₁ and 433 ₂ may also alternatively or additionally engage in circumferential radial grooves on the portion of the coupling formation 412 projecting into the pipette tip 418.

In Fig. 5b an activation state of a current supply of the electromagnet 428 is shown. Due to the magnetic field emanating from the electromagnet 428, the locking portions 433 ₁ and 433 ₂ in the radial direction are deformed away from the protruding into the pipette tip 418 portion of the coupling formation 412, so that the in Fig. 5a recognizable frictional lock is eliminated. The pipetting tip 418 is thus unlocked and can be stripped in the axial direction of the coupling formation 412 or can fall from this axially due to gravity. To assist in deforming the locking portions 433 ₁ and 4332, the pipetting tip 418 may be lined with a ferromagnetic shell 450. This leads and amplifies in its extension range from the electromagnet 428 when it is energized outgoing magnetic field. The latching sections 433 ₁ and 433 ₂ can then come into contact with portions of the ferromagnetic shell 450 when the electromagnet 428 is energized, as shown in FIG Fig. 5b is shown. This provides a sufficient annular gap between the pipette tip 418 and the section of the coupling formation 412 protruding into it in order to be able to remove the pipetting tip 418 axially from the pipetting device 410 with little force.

In all the embodiments shown, the locking body is preferably at least in its exposed to the atmosphere and possibly applied to the pipette tip outer surface area formed by an uninterrupted polymer skin so that it can lock not only the pipette tip on the coupling formation, but also one between the pipette tip and the coupling formation can seal existing annular gap.

In the fifth embodiment, the portions of the locking body which are exposed to the atmosphere and are optionally exposed to the portion of the coupling formation projecting into the pipetting tip are preferably formed by a continuous polymer skin.

Claims (26)

1. A pipetting apparatus for aspirating and dispensing liquid, having a coupling configuration (12; 112; 212; 312; 412) for coupling a pipetting tip (18; 118; 218; 318; 418), embodied separately from the pipetting apparatus, thereonto, the coupling configuration (12; 112; 212; 312; 412) being passed through by a pipetting channel (14; 114; 214; 314; 414) that extends through the coupling configuration (12; 112; 212; 312; 412) along a channel path (16; 116; 216; 316; 416), such that a deformable locking body (30; 130; 230; 330; 430) that, in the coupled-on state in which a pipetting tip (18; 118; 218; 318; 418) is coupled onto the coupling configuration (12; 112; 212; 312; 412), is arranged around the pipetting channel (14; 114; 214; 314; 414) and radially between the coupling configuration (12; 112; 212; 312; 412) and pipetting tip (18; 118; 218; 318; 418) interacts with the coupling configuration; the pipetting apparatus further comprising a locking-body actuation apparatus (28; 128; 228; 328; 428) that is embodied and activatable to bring about a deformation of the locking body (30; 130; 230; 330; 430), the locking body (30; 130; 230; 330; 430) having different radial extent states with reference to the channel path (16; 116; 216; 316; 416) depending on different activation states of the locking-body actuation apparatus (28; 128; 228; 328; 428),
   wherein the locking body (30; 130; 230; 330; 430) encompasses a material modifiable in shape by modification of a magnetic field passing through the locking body (30; 130; 230; 330; 430); and the locking-body actuation apparatus (28; 128; 228; 328; 428) is embodied to modify a magnetic field passing through the locking body (30; 130; 230; 330; 430), the material modifiable in shape by way of a magnetic field being a polymer filled with permanently magnetizable and/or permanently magnetized particles.
2. The pipetting apparatus according to Claim 1, wherein the material modifiable in shape by way of a magnetic field is a polymer, in particular PVA or silicone, filled with permanently magnetizable and/or permanently magnetized iron carbonyl particles.
3. The pipetting apparatus according to Claim 1 or 2, wherein the permanently magnetizable and/or permanently magnetized particles have an average particle diameter in the range from 1 to 30 µm, preferably 1 to 20 µm, particularly preferably 1 to 10 µm.
4. The pipetting apparatus according to one of the preceding claims, wherein the polymer filled with permanently magnetizable and/or permanently magnetized particles encompasses, in the cured, operationally ready state, 80 to 60 wt% permanently magnetizable and/or permanently magnetized particles and 20 to 40 wt% polymer compound.
5. The pipetting apparatus according to one of the preceding claims, wherein the locking body (30; 230; 330; 430) encompasses a continuous ring, in particular is a continuous ring.
6. The pipetting apparatus according to one of the preceding claims, wherein the locking body (230; 330; 430) comprises: a fastening portion (231; 331; 431) embodied for fastening it onto a structure carrying it; and an, in particular lip-shaped, locking portion (233; 333; 433) that protrudes axially and/or radially from it and, by deformation relative to the fastening portion (231; 331; 431), is embodied for locking a pipetting tip (218; 318; 418) on the coupling configuration (212; 312; 412) and for unlocking it.
7. The pipetting apparatus according to one of the preceding claims, wherein at least one outer surface, exposed to the atmosphere, of the locking body (30; 130; 230; 330; 430) comprises a continuous polymer skin.
8. The pipetting apparatus according to one of the preceding claims, wherein the locking-body actuation apparatus (28; 128; 228; 328; 428) encompasses a magnet (28; 128; 228; 328; 428), preferably a magnet (28; 128; 228; 328; 428) rotationally symmetrical with respect to the channel path (16; 116; 216; 316; 416), which is embodied to modify a magnetic field passing through the locking body (30; 130; 230; 330; 430) in order to implement different activation states of the locking-body actuation apparatus (28; 128; 228; 328; 428), the pipetting apparatus further comprising a control apparatus (24) that interacts with the locking-body actuation apparatus (28; 128; 228; 328; 428) in order to modify the magnetic field passing through the locking body (30; 130; 230; 330; 430) and thereby to modify the activation state of the locking-body actuation apparatus (28; 128; 228; 328; 428).
9. The pipetting apparatus according to Claim 8, wherein the magnet (28; 128; 228; 328; 428) is an electromagnet (28; 128; 228; 328; 428), and the control apparatus (24) is embodied to modify the current intensity of the current flowing through the electromagnet (28; 128; 228; 328; 428).
10. The pipetting apparatus according to Claim 9, wherein a conductor coil of the electromagnet (28; 128; 228; 328; 428) is provided in the coupling configuration (12; 112; 212; 312; 412) surrounding the pipetting channel (14; 114; 214; 314; 414).
11. The pipetting apparatus according to Claim 9 or 10, wherein a ferromagnetic yoke limb (140a, 140b; 240a, 240b; 340a, 340b) is located axially oppositely from the conductor coil of the electromagnet (28; 128; 228; 328; 428), with reference to the channel path (16; 116; 216; 316; 416), at at least one of its axial longitudinal ends, preferably a respective ferromagnetic yoke limb (140a, 140b; 240a, 240b; 340a, 340b) is located axially oppositely at both of its axial longitudinal ends in such a way that the conductor coil is located axially between the two yoke limbs (140a, 140b; 240a, 240b; 340a, 340b).
12. The pipetting apparatus according to one of Claims 9 to 11, wherein a yoke base (140c; 240c; 340c) is located radially oppositely from a conductor coil of the electromagnet (28; 128; 228; 328; 428), with reference to the channel path (16; 116; 216; 316; 416), preferably on the side located radially closer to the channel path (16; 116; 216; 316; 416), the yoke base (140c; 240; 340c) particularly preferably being a winding carrier of the conductor coil.
13. The pipetting apparatus according to Claim 11 and 12, wherein the yoke base (140c; 240c; 340c) and the yoke limb (140a, 140b; 240a, 240b; 340a, 340b), preferably the yoke base (140c; 240c; 340c) and both yoke limbs (140a, 140b; 240a, 240b; 340a, 340b), are embodied in one piece.
14. The pipetting apparatus according to one of Claims 11 to 13, wherein a radially outward-facing radial end surface (140a1, 140b1) of a yoke limb (140a, 140b) extends over an axial region of extent, the locking body (130) being located in that axial region of extent of the end surface (140a1, 140b1) but radially outside it, in particular directly radially adjoins the end surface (140a1, 140b1), a plurality of yoke limbs (140a, 140b), in particular two yoke limbs (140a, 140b), preferably being provided with an axial spacing from one another, each of which has a radially outward-facing radial end surface (140a1, 140b1) that extends over an axial region of extent, the locking body (130) encompassing a plurality of partial locking bodies (130₁, 130₂), in particular two partial locking bodies (130₁, 130₂), each of which partial locking bodies (130₁, 130₂) is located in the axial region of extent of another radial end surface (140a1, 140b1) of the plurality of radial end surfaces (140a1, 140b1) but radially outside it.
15. The pipetting apparatus according to one of Claims 11 to 14, wherein the yoke limb (140a, 140b; 240a, 240b; 340a, 340b) or, in the case of several yoke limbs (140a, 140b; 240a, 240b; 340a, 340b), at least one yoke limb (140a, 140b; 240a, 240b; 340a, 340b), preferably all yoke limbs (140a, 140b; 240a, 240b; 340a, 340b), is/are embodied to be radially shorter than the coupling configuration (112; 212; 312; 412) in which the yoke limb or limbs (140a, 140b; 240a, 240b; 340a, 340b) is/are received.
16. The pipetting apparatus according to one of Claims 9 to 15, wherein a ferromagnetic yoke (140; 240; 340) is located radially inwardly, on both axial sides, and radially outwardly oppositely from a conductor coil of the electromagnet (128; 228; 328), the ferromagnetic yoke (140; 240; 340) comprising, in a region located radially externally and/or axially oppositely from the electromagnet (128; 228; 328), a gap (132; 232; 332) which interrupts the yoke (140; 240; 340) and in which the locking body (130; 230; 330) is arranged.
17. The pipetting apparatus according to Claim 16, wherein the locking body (130; 230; 330) is arranged, in the gap (132; 232; 332) that interrupts the yoke (140; 240; 340), in such a way that in a predetermined activation state of the locking-body actuation apparatus (128; 228; 328), in particular in a predetermined energization state of the electromagnet (28; 128; 228; 328; 428), it is provided, accompanied by formation of an interstice (242; 342), at a distance from at least one of the yoke portions (140a, 140b, 140d; 240d1, 240d2; 340d1, 340d2) delimiting the gap (132; 232; 332).
18. The pipetting apparatus according to Claim 16 or 17, wherein a region (240d1, 340d1), located closer to an insertion end (212a; 312a) of the coupling configuration (212; 312), of a yoke portion (240d; 340d), which is located radially externally oppositely from the electromagnet (228; 328), is embodied to be radially thicker than a region (240d2, 340d2), located farther from the insertion end (212a; 312a), of the yoke portion (240d; 340d), the two regions (240d1, 240d2; 340d1, 340d2) of the yoke portion (240d; 340d) preferably being separated by the gap (232; 332).
19. The pipetting apparatus according to Claim 18, wherein the two regions (240d1, 240d2; 340d1, 340d2) of the yoke portion (240d; 340d) having different radial thicknesses are separated by the gap (232; 332), an outer surface portion (244; 344) of the radially thinner yoke portion (240d2, 340d2), located farther from the insertion end (212a; 312a) of the coupling configuration (212; 312), being embodied as an abutment surface portion (244; 344) for temporary abutment thereon of a region of the locking body (230; 330), the temporary abutment occurring depending on the activation states of the locking-body actuation apparatus (228; 328).
20. The pipetting apparatus according to one of Claims 18 or 19, wherein the locking body (230; 330) is provided, independently of the activation state of the locking-body actuation apparatus (228; 328), on an outer surface region (241; 341) of the radially thicker yoke portion (240d1; 340d1), preferably on an exposed end surface (241; 341) thereof facing in an axial direction.
21. The pipetting apparatus according to one of the preceding claims, wherein there is provided, radially between the coupling configuration (212) and a portion of the locking body (330), a support ring (346) against which the locking body (330) braces, preferably abuttingly braces, depending on activation states of the locking-body actuation apparatus (328).
22. The pipetting apparatus according to Claim 21, wherein the radial dimension of the support ring (346) changes in an axial direction, preferably increases proceeding in an axial direction from an end closer to the insertion end (312a) of the coupling configuration (212) toward an end farther therefrom.
23. The pipetting apparatus according to one of Claims 9 to 22, wherein the magnet (28) encompasses a plurality of conductor coils (28a, 28b), in particular two conductor coils (28a, 28b), that are provided with an axial spacing from one another, the locking body (30) being arranged axially between two conductor coils (28a, 28b) provided with an axial spacing from one another, preferably between two directly axially adjacent conductor coils (28a, 28b).
24. The pipetting apparatus according to one of the preceding claims, wherein the locking body (30; 130) is provided on the coupling configuration (12; 112), preferably in a radial groove (32; 132) thereof.
25. The pipetting apparatus according to one of the preceding claims, wherein it encompasses a pipetting tip (18; 118; 218; 318; 418), and the locking body (30; 130; 230; 330; 430), in the coupled-on state,

    a) engages behind a radial projection, protruding toward the channel path (14; 114; 214; 314; 414), of the pipetting tip (18; 18; 218; 318; 418); or

    b) extends into a radial recess (34; 134a, 134b; 234; 334) of the pipetting tip (18; 118; 218; 318; 418) which proceeds radially away from the channel axis (16; 116; 216; 316; 416).
26. The pipetting apparatus according to one of Claims 1 to 24, wherein it encompasses a pipetting tip (418), and the locking body (430) is provided on the pipetting tip (418) and is fixedly connected thereto, the locking body (430) preferably being provided on a counterpart coupling configuration (426) that, with the pipetting tip (418) in the coupled-on state, radially externally surrounds the coupling configuration (412) of the pipetting apparatus.

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