Patent Application
20090097948
The present invention relates to a device for moving liquid containers, which comprises a support unit implemented to receive liquid containers; a base unit, in relation to which the support unit is mounted as essentially horizontally freely oscillating using connection elements; and movement means for moving the support unit in relation to the base unit.
Industrial branches which are concerned with biochemical technologies in pharmaceutical research and/or in clinical diagnostics, for example, require facilities for processing liquid volumes and liquid samples. Automated facilities typically comprise an individual pipetting device or multiple pipetting devices, which are used on liquid containers, which are often located on the work table of a workstation. Such workstations are often capable of executing greatly varying work on these liquid samples, such as optical measurements, pipetting, washing, centrifuging, incubation, and filtration. One or more robots, which operate according to Cartesian or polar coordinates, may be used for sample processing on such a workstation. Such robots may support and reposition liquid containers, such as sample tubes or microplates. Such robots may also be used as so-called “robotic sample processors” (RSP), for example, as a pipetting device for aspirating and dispensing, or as a dispenser for distributing liquid samples. Such facilities are preferably monitored and controlled by a computer. A decisive advantage of such facilities is that large numbers of liquid samples may be processed automatically over long periods of time of hours and days, without a human operator having to engage in the processing process.
Stirring devices (“stirrers”), which have been known for some time, use a moving body immersed in the liquid of a liquid container retained fixed in place to mix the materials present in this liquid. This stirring body is externally driven mechanically directly (as in a kitchen mixer) or using magnetic coupling (cf., for example, U.S. Pat. No. 4,199,265 or EP 1 188 474).
In contrast, shakers, which are also known in practically all laboratories which are concerned with mixing materials with liquid, move the liquid container itself. Such shakers which move the liquid containers in a thermostatically controlled bath are known, for example, from U.S. Pat. No. 3,601,372: the support device of this shaking apparatus is not freely oscillating, but rather fixed, however, it is connected via three crankshafts to a stationary intermediate floor so it is movable and may execute a circular movement corresponding to the deflection of the crankshaft. Permanent magnets directed downward are attached to one of these crankshafts, which produce a magnetic coupling to a permanent magnet situated outside the water bath and driven via a fixed motor. The motor drive and the support surface are at least mechanically decoupled from one another by this configuration. Other shakers execute a rapid circular movement using a rubber hollow spherical cap, in which a test tube or a sample tube is retained by hand. Shakers which move a platform linearly or circularly in a horizontal plane are also known; baths for staining polyacrylamide gels are laid on these platforms, for example. Rocking platforms are also known.
Further shakers equipped with solenoid drives, however, are known from U.S. Pat. No. 5,259,672, GB 2 254 423, FR 934 278, and EP 1 201 297. All of these devices share the feature that they comprise exciter coils and pole cores, the exciter coils being fastened to a support device and the pole cores to a base plate and/or a housing (or vice versa). The disadvantage results from this configuration of the two main components of the solenoids and the at least magnetic coupling between the support device and the housing connected thereto that shocks of the surroundings are transmitted to the support device and vibrations of the support device are transmitted to the surroundings.
In connection with the present invention, whenever a device for moving liquid containers is referred to, it is thus a shaker which moves the liquid containers to mix, shake, or stir material mixtures. Such material mixtures may comprise suspensions, solutions, and emulsions.
U.S. Pat. No. 5,409,312 discloses a device, using which a magnetic stirrer may be converted into a magnet-driven orbital shaker. This device comprises a horizontally situated, rectangular base plate and a support plate, also rectangular, situated parallel thereto. Four ball bearings are situated in the corners and opposite one another, which allow the support plate for receiving a liquid vessel to execute a free or circular orbital movement. The support plate has a circular magnet in the center on its bottom side, and is thus magnetically coupled to the rotatable magnet of the magnetic stirrer. Such magnetic stirrers are known, however, for discharging strong vibrations to their surroundings, in particular onto the table on which they stand.
U.S. Pat. No. 6,508,582 discloses an electromagnetically driven linear shaker for microplates, which causes a support plate connected via leaf springs to a base plate to vibrate up to frequencies of 120 Hz (7200 reciprocal movements per minute). The microplates, whether a single standard plate, a single “deep-well microplate”, or entire stacks thereof, are fixed on the support plate using clamping devices. On one hand, these clamping devices are not suitable for automated or robotic charging of the support plate with such microplates. On the other hand, the discharge of strong vibrations to the substrate is also a concern here, because the direct movement of the support plate and all liquid containers situated thereon requires a correspondingly strong electromagnet.
Published patent application US 2003/0081499 A1 discloses an electromagnetically or mechanically driven multi-directional shaker for microplates or sample tubes. A first support plate is suspended on leaf springs in relation to a base plate, so that it may oscillate essentially horizontally and freely in a specific first direction. A second support plate is suspended on this first support plate on leaf springs in such a way that it may oscillate essentially horizontally and freely in a second direction perpendicular to the first direction. The oscillations are generated by two electromagnets oriented in the particular oscillation directions, in that a core fixed on the particular support plate is provided for each support plate, which is partially inserted into each of the electromagnets. Alternatively, the support plates are oscillated by two electric motors oriented perpendicular to the particular oscillation direction using eccentric drive wheels directly impinging the edge of the particular support plate; in this case, springs counteract the eccentric drive wheels. The discharge of strong vibrations to the substrate is also a concern here, because the direct movement of the support plate and all liquid containers situated thereon requires a correspondingly strong electromagnet or a correspondingly strong electric motor.
The present invention is based on the object of suggesting an alternative device for moving liquid containers, which remedies or at least minimizes the disadvantages from the prior art.
This object is achieved according to a first aspect in that a device as disclosed herein is suggested. Such a device according to the present invention for moving liquid containers comprises:
The device according to the present invention is characterized in that the support unit comprises at least one support element, on which at least one movement mass is fastened so it is movable. This at least one movement mass interacts with movement means—fastened to the same support element—and is movable by these movement means. The movements of this at least one movement mass set the same supporting support element and the liquid containers received using the support unit into corresponding counter movements.
This object is achieved according to a second aspect in that a method as disclosed herein is suggested. In such a method according to the present invention for moving liquid containers, in particular using a device as just cited, liquid containers are received using a support unit—which is mounted using connection elements so it is essentially horizontally freely oscillating in relation to a base unit—and this support unit is moved in relation to the base unit using movement means. The method according to the present invention is characterized in that at least one support element of the support unit, on which at least one movement mass is fastened so it is movable, is moved using movement means—fastened to the same support element—which interact with this at least one movement mass, in such a way that the movements of this at least one movement mass set the same supporting support element and the liquid containers received using the support unit into corresponding counter movements.
Additional, preferred, and inventive features result from disclosure of this application and the attached drawings.
The device and the method according to the present invention are explained in greater detail on the basis of schematic drawings of exemplary embodiments, which do not restrict the scope of the present invention.
The electromagnetic coil 6 is mounted fixed on the support unit 3. The oscillator 9 or “moving magnet” is mounted on the support unit 3 so it is movable. This mounting comprises two sliding rods 12, which are each mounted to slide in a pair of sockets 13. Two stop plates 14 delimit the horizontal mobility of the oscillator 9 and of the movement mass 8. In order that the transverse flanges 15 of the oscillator 9 do not hit the stop plates 14, strong permanent magnets 17 homopolar to one another are situated on the transverse flanges 15 and also on the stop faces 16 of the stop plates 14 directed toward them. By the repelling effect of the like poles of these strong permanent magnets 17 opposite one another, the transverse flanges 15 are additionally accelerated in the opposite direction after braking, so that these permanent magnets 17 also act as a drive—at least in direct proximity to the stop plates 13. Depending on the strength and number of the permanent magnets 17, these stop springs or this drive effect may be strengthened or attenuated. If the movement mass 8 that is movably situated on the support unit 3 is moved by these movement means 6, the movement of this movement mass 8 sets the support unit 3 and the liquid containers 2 received thereby (cf.
It is clear that it is sufficient for a linear movement of the support unit 3 if only one movement mass 8 is fastened thereon. If the support unit 3 is to execute a more complex movement, a rotating movement mass 8 may be fastened thereon. However, the linear mounting shown having two sliding rods 12 must be replaced by another mounting, which allows the support unit 3 a rotational movement opposite to the rotating movement mass 8. For this purpose, the support unit 3 may be suspended on limp, flexible elements 18 such as cords, narrow coiled springs, and the like. Alternatively thereto, the support unit 3 may also be supported on springy, stiff elements 19 such as wires, wide coiled springs, and the like. The support unit 3 comprising a single support element 20 may thus execute a rotating reciprocating movement which is opposite to the rotational movement of a rotary movement mass 8. This alternative, orbiting movement of the movement mass 8 may be caused by an electric motor, on whose driveshaft the movement mass 8 is eccentrically fastened (not shown).
If the support unit 3 is to execute a rotational movement without rotating electric motors and eccentrically situated movement masses 8 being used, the support unit 3 preferably comprises two support elements 20,21.
An especially preferred first embodiment of the device according to the present invention for moving liquid containers having first and second support elements 20,21 is shown in
The leaf springs 22 or connection elements 7 fastened to the bent-up support parts 23 of the base unit 4 are clamped hanging here and support bent-up hanging parts 24 of the first support element 20. This first support element 20 comprises bent-up support parts 25, on which connection elements 7, also implemented as leaf springs 22, are again clamped hanging. These leaf springs 22 are also fastened clamped on the bent-down support element 21. Three leaf springs are also preferably provided here, which connect the first and second support elements 20,21 to one another.
The horizontal section 27 of the bent-up part 26 of the second support element 21 forms the effective support surface 28 of the support unit 3, which comprises the first and second support elements 20,21. Preferably, each of the support elements 20,21 is equipped with one movement mass 8 and one movement means 6 corresponding to the illustrations in
In general, two support elements 20,21 must be used to utilize essentially torsion-resistant leaf springs made of steel. For example, the support element 20 executes essentially horizontal reciprocating movements exclusively in the X direction, for example, and the support element 21 executes essentially horizontal reciprocating movements exclusively in the Y direction perpendicular thereto, for example. This configuration successfully prevents or minimizes undesired and uncontrollable increasing oscillation of the support surface 28, which supports a liquid container, of the support element 3 in a reciprocating movement about a Z axis.
Such increasing oscillation may particularly occur with support surfaces 28 suspended on cords or wires, which support a microplate having asymmetrical partially filled and partially empty wells. The embodiment of a device for moving liquid containers shown in
In particular for incubators or fermenters used in biotechnology, bumpless shaking and/or mixing of cell cultures is made possible by the device according to the present invention. A vortex effect is even achievable in the liquid containers by the freely oscillating movement of the support surface 28, without the device discharging vibrations to the immediate surroundings. No radial forces arise on the device due to the freely oscillating suspension of all support elements 20,21 and by the movement means 6 and movement masses 8 inherent in these freely oscillating support elements, so that the device does not “travel”. The preferred suspension of the support elements 20,21 on leaf springs does not cause any appearances of fatigue in the fastening or any uncontrolled loosening of screws by vibrations.
The actual movement of the support plate and thus also the liquid containers 2 is preferably ascertained for each movement direction in the X and Y axes using one Hall sensor each. This actual movement detection is used as a manipulated variable in the activation of the movement means 6 and movement masses 8. Activation of the movement means 6 using 2 frequencies and 2 deflections is especially preferred. The deflection of the support surface 28 may be tailored to the height and the diameter of the liquid containers 2, in particular the wells of a microplate. The smaller the deflection, the higher may be the selected frequency. The preferred deflection is approximately ⅓ to ½ the well diameter, which corresponds to a preferred deflection of approximately 3 mm for deep-well microplates. The frequency of an individually activated device according to the present invention is preferably 0.1 to over 4000 Hz.
In addition to linear reciprocating movements in any arbitrary direction in the essentially horizontal plane of the support plate, arbitrary, preferably cyclic movement patterns may be generated using the freely oscillating suspension of the two support elements 20,21 in
It is preferable to pipette samples directly out of or into a liquid container 2 on the support surface 28. The analysis of the samples using optical analysis, detection of their pH or temperature, but also the robotic use of tweezers for removing sample parts are fundamentally desirable. Therefore, a device 1 according to the present invention preferably comprises a blocking apparatus, using which the support unit 3 and liquid containers 2 received thereon may be fixed in a predetermined position. Depending on the selected spring constant and/or number of the leaf springs, the support surface 28 is held so calmly that such a blocking apparatus may even be dispensed with.
Devices 1 which comprise a housing 31, which has an opening 33 on its top side 32, through which a liquid container 2, in particular a microplate, may be laid on the support unit 3, are also especially preferred, the support unit 3 comprising a fixing mechanism 4 for fixing the liquid container 2. In order that this laying may be performed robotically and/or automatically, the fixing mechanism 4 for fixing the liquid container 2 on the support unit 3 is preferably implemented so it may be loosened by a microplate handling robot.
As is obvious from
Furthermore, such devices 1 are preferably implemented as incubators, in that they comprise a temperature-controlled hot plate and thermal insulation situated on floor 34 and cover 35 as well as on all sides 36, which also closes all openings 33,38. Alternative, preferred devices 1 are implemented as a cooling chamber, in that they comprise a temperature-controlled cooling plate and thermal insulation situated on floor 34 and cover 35 as well as on all sides 36, which also closes all openings 38. Peltier elements or so-called “heat pipes” are preferably used for the incubators or cooling chambers.
Devices for moving liquid containers deviating from the devices shown or described are part of the present invention, if one or more movement means 6 and one or more movement masses 8 are movably situated on their support unit, which are movable by these movement means and which set the support unit and the liquid containers thus received into corresponding counter movements by their movements.
The part of the support unit 3 identified as the support surface 28 may also be implemented as a coherent support frame or as a separate multiplex surface. Notwithstanding the embodiments shown or described up to this point, each rotating movement mass 8 may be magnetically connected to a rotating part of movement means 6. The movement means 6 are preferably then an electric motor, which is attached to the base unit 5 and on whose drive axis a permanent magnet is eccentrically fastened. The corresponding movement masses 8 are connected via a rotation axis to the support elements 20,21 or to the support unit 3 respectively. The rotation axis of the movement means 6 is essentially situated in the geometric axis of the corresponding movement mass 8. In addition, the movement masses 8 also have eccentrically fastened permanent magnets, which represent the opposite pole to the permanent magnets of the corresponding movement means 6. Because the two heteropolar permanent magnets of movement means 6 and corresponding movement mass 8 rotate around the shared geometric axis, in relation to which they are fastened on their individual rotational axes eccentrically offset by essentially the same amount, a rotating, magnetic coupling results between each movement means 6 and a movement mass 8 assigned thereto.
This configuration is particularly suitable for automated multiple configurations of fermenters or incubators in biotechnology, which have rotatable movement masses 8 each having at least one permanent magnet on one of their external walls or on their cover or floor. These fermenters are preferably equipped with stirring devices which are operationally linked to the movement masses 8. This operational link may be of a mechanical or magnetic nature. If these fermenters are conveyed from one stirring station to the next (preferably remote-controlled), the identically or differently situated movement means 6 of the next stirring station interact with one or more of the movement masses 8 of the fermenters, so that a movement tailored to the stirring station may be provided in the liquid located in the fermenters. The stirring stations may also differ in temperature and in other physical or chemical parameters. Alternatively, the entire fermenter may also be suspended freely oscillating and be brought into corresponding counter movements by the movement masses 8.
Although this embodiment was only discussed on the basis of fermenters, it is also suitable for other containers, in which liquids are to be stirred or otherwise moved especially carefully.
Identical reference numerals identify corresponding parts in figures, even if they are not cited in the description.
According to an especially preferred second embodiment (cf.
Notwithstanding this illustration, two movement masses 8, which move linearly back and forth either in the X direction or in the Y direction, e.g., in the direction of the axes of symmetry 11′ or 11″ (cf.
All of the movements described here and above may be identified as the actual reciprocating movements of the support surface 28 about a mass center of gravity, this mass center of gravity being essentially determined in connection with the second preferred embodiment shown in
In connection with the suspension of the support surfaces 28 and/or the support elements 20,21 on flexible, limp elements, the problem of possible undesired rising oscillation has already been discussed. If this problem occurs when flexible, limp elements are used or in the second embodiment (cf.
One skilled in the art will optimize the parameters just listed in such a way that rising oscillation is successfully prevented. An eddy current brake of this type having a permanent magnet 45 has the advantage, inter alia, that it represents a completely passive system which does not require any type of controller. Such an individual eddy current brake is preferably provided for each of the support elements 20,21. A system having leaf spring suspensions may also be improved further by the use of such eddy current brakes.
| Number | Date | Country | Kind |
|---|---|---|---|
| 787/05 | May 2005 | CH | national |
This patent application claims priority of the Swiss patent application No. 0787/05 filed on May 4, 2005 and of the international application PCT/CH2006/000243 filed on May 4, 2006, the whole disclosures of these applications being incorporated by reference herein for all purposes.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/CH2006/000243 | 5/4/2006 | WO | 00 | 10/30/2008 |
