Patent Application
20050260101
The present invention relates to a closure element or a closure system comprising such an element for containers or vessels with circular openings. The closure element or closure system is very well suited for carrying out chemical, biochemical, biological and/or medical analyses or reactions, in particular in medical diagnostics and chemical or biochemical analysis, but also for operating sequences of production.
The problem often arises that open liquid containers should be closed in working processes between individual working steps. Hence, for example in order to avoid evaporation, impurities due to feed, contamination, condensation precipitates, spilling during transport and others, as well as losses in quality associated therewith. Currently, threaded closures, snap-on lids, films, flexible and fixed cover caps are used for this. Since the handling of these closures is time-consuming, technically difficult and impractical for rapid working processes and large series with many vessel openings (intermediate placing of the cover and danger of contamination), it is often completely dispensed with and a loss in quality accepted.
A typical example of a situation in which material is repeatedly removed from a larger quantity of the same vessels over a longer period of time and is therefore left to stand open, is the analytical investigation laboratory. In a medical-diagnostic laboratory, there are for example patient samples (blood, urine etc.), in which various investigations are carried out. After the first opening of the test tube, during a day material samples are removed again and again for new analyses. In a sample number of 50 to 50,000 daily, they cannot be closed again in between individually using the above-mentioned systems. The expense in terms of time and material for this is too high.
Similar situations arise in laboratories of biotechnology, biochemistry and analytical chemistry, or in the production of chemicals, pharmaceuticals, cosmetics and foodstuffs or luxury foods.
For traditional bottles, sphere closures were described a long time ago, see German Patentschrift No. 633 289 (1936) and French 1 089 145 (1955).
The object of the invention was therefore to provide a possibility of being able to reliably close vessels or containers even in the problematic situations outlined above.
To achieve this object, according to the invention a closure element was provided for closing a container or vessel with circular opening, which adopts the shape of a sphere, a sphere segment, a sphere cutout or a sphere layer and is able to releasably close the circular opening at the sphere surface or spherical surface.
In a further object of the invention, such a closure element together with a selectable container or vessel with circular opening forms constituents of a closure system.
A surprisingly simple, versatile, reliable and cost-effective possibility is provided by the present invention of effectively closing open containers, in particular those containing liquids, even in lengthy working processes or production processes and thus avoiding losses in quality. The concept of closing circular openings according to the invention is easily accessible to automisation, which is of considerable advantage for medical diagnostics and other analysis. Since the closure element of the invention on the one hand closes effectively, but on the other hand can be easily released, it is of considerable benefit as a reversible, temporary closure system even for longer breaks in lengthy working processes or methods. With exclusion of contamination, the closure element of the invention can be re-used or designed as an inexpensive disposable article.
The aspects of the present invention, to which the closure element, the closure system as well as processes and devices using the closure concept belong, and the further advantages and preferred embodiments of the invention are illustrated in more detail below with reference to the attached drawings.
The closure system according to the present invention may be designed in different shapes, assuming that the element, at least in the region with which the circular opening of the container or vessel is to be closed, a sphere surface or spherical surface is provided.
In the preferred case, the closure element has the shape of a (full) sphere, as shown in
The edge on the circular opening of the cylindrical vessel 102a is shown by the reference number 103 in the perspective view (see representation left). In a preferred embodiment, this edge 103 is bevelled, as a result of which the container or the vessel at the circular opening has a surface facing the closure element, which is essentially complementary to the sphere surface of the closure element in the closure region. The closure element rests better on the circular opening in this manner and both the positional stability and the tightness of the closure is improved. However, to simplify production it is not necessary to bevel the edge of the opening, on which the closure sphere sits.
The positional stability of the closure sphere may be positively influenced by further factors. One important factor in this sense is the diameter of the sphere relative to the internal diameter of the round opening. By matching the diameter of the sphere relative to the internal diameter of the opening, the “immersion depth” and hence the stability is determined. This is shown in
A further factor which determines the positional stability of the closure sphere, is the specific weight of the sphere. With increasing specific weight, the sphere thus presses more strongly on the opening with the increasing dead weight per unit surface area and thus increases the positional stability. This factor may be varied and adjusted easily by selecting an appropriate sphere material and the thus predetermined specific weight depending on the requirements.
In addition to the full sphere described, further shapes of the closure element of the invention are possible.
Further designs of the closure element are a sphere cutout (sphere sector), in which, starting from a sphere segment, on its base circle a sphere section is formed, the tip of which coincides with the central point of the base circle and lies for example in the central point of the fictitious sphere, and a sphere layer, in which, starting from a sphere segment, a further, flat section exists parallel to the first sectional plane.
All designs described of the closure element of the invention correspond as regards their function since the closure of the circular opening is effected at the sphere surface or for the modifications of the full sphere on the remaining, spherical surface of the sphere segment, of the sphere cutout or of the sphere layer. In the embodiments deviating from a full sphere, the statements made above in connection with the full sphere should be applied accordingly. Regarding the description for selecting the diameter, an imaginary full sphere, which is the basis of the particular modification, should thus be used.
In a further embodiment of the invention, the closure sphere may be additionally fixed, if required, by suitable locking elements, so that an indeed reversibly releasable, but more firm closure is possible for longer closure times, for example for transport, archiving, in particular low-temperature storage, etc. Such additional fixing can be easily realised. One possible design of locking is shown in
The closure element of the invention may be formed, if required, from one or from more different materials or in the form of a hollow sphere. For example the spherical closure element may be composed of different constituents. Hence, any base material may be coated with a material of certain functionality completely or partly with formation of a surface layer. Hence, the entire closure element or at least the part region of the sphere surface or the spherical surface, which should engage in the circular opening to close the container or vessel, may be made from a material which fulfils at least one of the functions, that the condensation of liquid is inhibited or prevented, that solvent resistance and heat resistance are guaranteed, and that the closure element has high dimensional stability and a low coefficient of expansion. Prevention of liquid condensation is particularly advantageous in analytical processes, since for liquid samples, the concentration of the dissolved materials may be increased by reducing the liquid volume due to condensation on the closure part and thus the analysis results distorted. Also solvent resistance and heat resistance (in particular when the closure element is subjected to recycling cleaning measures, such as washing or autoclaving), high dimensional stability (even in the heat) and a low thermal coefficient of expansion have a favourable effect in the sense of a tight closure and prevention of contamination. Suitable materials for inhibiting or preventing liquid condensation are known, for example fluorinated hydrocarbons, such as polytetrafluoroethylene (PTFE) or fluorine-containing thermoplastics, such as tetrafluoroethylene-hexafluoropropylene copolymer (Teflon@), perfluoroalkoxy copolymer, ethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride, polyvinyl fluoride, polychlorotrifluoroethylene, ethylene-chlorotrifluoroethylene copolymer or the like. Surface treatment of a base material of the closure element is also suitable in order equip the closure element with the required function, for example hydrophobisation by suitable silanes or silicones. Solvent stability is also achieved at the same time using the said materials, but also using polyolefins, such as polyethylene and polypropylene, polyvinyl chloride, polymethylmethacrylate or the like. Dimensionally stable and heat-resistant materials are, for example polypropylene, polycarbonate, polymethylmethacrylate, fluorine-containing plastics, such as polytetrafluoroethylene and polyesters. Materials having relatively low, linear coefficient of thermal expansion are likewise known, for example hard rubber, polycarbonate, polymethylmethacrylate, phenol-formaldehyde resins, urea-formaldehyde resins, unsaturated polyester resins and in particular inorganic materials, such as glass, porcelain and metals, such as aluminium or steel.
Furthermore, it is preferable that the closure system of the invention can be closed to be essentially gas-tight and/or liquid-tight. This may be realised in turn by the use of suitable materials know per se for the functions of gas-tightness or for liquid sealing and which are optionally applied only to the relevant contact point with the circular opening. Further possibilities optionally realised at the same time are produced by suitable constructive measures on the closure system of the invention. The measures already described for observing a relatively high dead weight for the closure element, bevelling on the opening ring to increase the contact surface or the design of a locking device, which may increase the compressive pressure of the closure element on the opening ring, have a positive effect even in this sense.
A further, advancing design according to the invention consists in that the closure element has an identification feature which visible at least externally. This brings advantages with it particularly for series investigations. Suitable identification features are, for example colour features, wherein complete, partial or only surface dyeing are suitable, as well as externally provided inscriptions, engravings, cipher or barcode or the like.
The application of the closure element of the invention is particularly well suited for repeated removal of certain liquid quantities (aliquots) from vessels and containers. Indeed, manual operation is easily possible, particularly for short series runs. However, a particular advantage of the closure system of the invention consists just in that it is easily accessible to mechanisation and automisation, particularly when, as is often the case, large series lengths and long analysis runs occur. In all cases, if required or necessary, a placing support, which has the same or similar circular openings as the containers or vessels to be closed, may serve to place the closure element. When using sphere segments or sphere layers, the closure element may also be placed stably on the base circle surface (see for example reference number 207 in
Mechanisation for automatic handling may be realised by suitable processing devices. Processes, in which the closure can be released, if required, by means of applying a magnetic field or by means of suction, are preferred as particularly advantageous and particularly easily accessible to automisation. These preferred embodiments of the present invention are illustrated in more detail below. In order to be able to release the closure with the circular opening by means of a producible magnetic field, the closure element of the invention preferably has a core which is formed from a magnetic material, in particular a paramagnetic material. Using the example of a full sphere as closure element, this is illustrated in
Reversible opening and closing of the vessel or container openings may be effected by introducing or switching off a magnetic field. This may take place, if required, selectively via a closure element, or at the same time via many closure elements. The strategy of opening can be selected and controlled by the geometry of the magnet used, which is preferably an electromagnet, as shown in
As shown in
The same applies for the alternative use of a sphere cutout (sphere sector) as closure element. In this case, the contact point on the magnetic device has a depression which is complementary to the cone section of the sphere cutout.
In the combination with a sphere section (sphere segment) as closure element, the geometry of the electromagnet used is shown in
In this case, the electromagnets 510 or 520 have a flat surface 511 or 521 facing the closure system, so that a flat boundary surface may be formed at the contact point with the base circle of the sphere segment 501, which is facing away from the opening of the vessel or container. The same applies in the case of a combination (not shown by a figure) with the sphere layer as closure element.
The design of the magnetic device, in particular its geometry and construction as well as its electrotechnical control, are easily possible for the expert taking into account the embodiments shown in
Alternatively, the closure element of the invention may be opened and closed reversibly according to requirement, in that the closure element is drawn in vertical direction by a suction device for opening, whereas for closing, the suction force of the suction device is reduced or removed in a state, in which the closure elements is situated above the container opening, for uncoupling the closure element from the suction device.
Modifications of this embodiment by applying a suction force are easily conceivable, inter alia, taking into account the shape of the closure element, the geometry and the mode of operation of the suction device as well as the possibility of single or multiple opening.
All conceivable or required types, which have circular or essentially circular openings, are suitable as containers or vessels. They may be firstly individual vessels or containers. In medical diagnostics and general analysis and there in particular in series investigations, so-called microcentrifuge tubes are normally used, which are normally formed from plastic resins, such as polypropylene, may accommodate liquid quantities of up to 0.25 ml, 0.4 ml, 0.5 ml, 1.5 ml or more (for example up to 5, 10 or 15 ml) and have circular openings with internal diameters in the range from 0.2 to 5 cm, normally in the range from 0.5 to 1.5 and in particular around 1 cm. These vessels and containers are also well suited to the closure system of the invention. The traditional closure systems likewise occurring in commercially available vessels, such as snap-on lids or threaded closures are however dispensable and may be replaced by the closure element of the invention. The closure system of the invention may thus span the containers, if required, individually, or span several, in combined or combinable form, in appropriate devices, so-called racks.
Alternatively thereto, a plurality of openings may be present in a common container or vessel. Of course, the explanations described above apply to the present invention, which in some cases have been made representative even for those containers or vessels having a plurality of openings, with reference to the simplified individual vessels shown in the attached drawings. In a case, which is typical and preferred for this, the container with the plurality of openings is present as a microtitre plate. Such microtitre plates are conventional for series investigations with assistance of devices for automatic processing. A schematic and exemplary representation for such a vessel is shown in
When using microtitre plates as a vessel, the concept of the invention is particularly useful for reversible, releasable closing by means of application of a magnetic field as described above. To carry out a closing mechanism according to this preferred embodiment, according to the invention a device for automatically carrying out series investigations on samples present in containers or vessels is also provided. Such investigations conventionally include, as for series investigations, pipetting steps for the removal and/or addition of liquid reagents or samples. The device comprises, in addition to conventional devices of pipetting machines known per se, the special magnetic device described above for reversible opening and closing of circular openings of containers or vessels by means of the closure elements of the invention. As already illustrated, the magnetic device is preferably a controllable electromagnet. Furthermore, the vessel is typically designed as a microtitre plate.
Using the closure element or the closure system as well as the previously described, special device according to the present invention, processes for chemical, biochemical, biological and/or medical analysis or reactions may now be carried out considerably more reliably and in a manner not susceptible to disturbance compared to the state of the art. Considerable advantages result particularly for series investigations. By applying a magnetic field or a suction force by appropriately provided magnetic devices or suction devices, the closure of the openings can be easily reversibly released. Hence, the circular openings of the containers or vessels may be closed before, between and/or after individual pipetting steps of the required analyses or reactions. The step of opening and closing can thus be repeated as required. Also, when using a vessel having a plurality of openings, both simultaneous opening or closing of several or all closure elements, or if required, the controlled and selective opening or closing of individual openings, is possible. If it is required to close or open a plurality of openings, optionally all openings of a common vessel at the same time, the closure elements may be present individually as separate elements. Nevertheless, it may be useful in such a case, to provide a plurality of closure elements corresponding to the plurality of openings, which are firmly connected to one another in each case, in order to simplify the construction of the closure system of the invention. In such a design, the plurality of closure elements are preferably designed in the form of sphere sections (sphere segments, such as for example half spheres) or sphere layers, which are firmly connected to one another via a common support on the side facing away from the openings. The closure unit may then be made, for example by shaping the plurality of spherical sections with the common support via usual shaping techniques, conventionally from suitable plastic materials, integrally to form a unit. Connection or attachment to the common support thus takes place via the base circle surfaces of the closure elements on the side facing away from the openings at such distances that the central points of these base circles and those of circular openings lying underneath essentially cover one another, preferably lie precisely plumb.
The closure element of the invention may be used, if required, once in the form of a disposable article, or alternatively it may be recycled by suitable measures after practical use within the framework of a required analysis or reaction. In order to exclude contamination for further analyses or reactions, measures for washing, autoclaving and the like are suitable for recycling depending on requirement profile and the choice of material for the closure element.
The closure element of the invention may be used generally for covering containers between the partial or complete filling or emptying of the containers. The containers are thus filled with liquids between the covering phases conventionally, for example by means of pipetting aids or pipetting machines, or liquids are removed. As becomes clear from the above description, the closure element and the closure system according to the present invention as well as the processes and devices described are particularly beneficial for use in medical diagnostics, in chemical or biochemical analysis or in the production of chemicals, pharmaceuticals, cosmetics, foodstuffs or luxury foods etc.
In the applications mentioned, the advantages of the invention come particularly to fruition, including simple and rapid handling of the reversible closure mechanism in small and large series, easily realisable, high ability for mechanisation and automisation, developing diverse areas of application and useful functions due to variable diameters and materials of the closure elements on the one hand and of the containers or vessels on the other hand, as well as cost-effective operation by recycling of the closure elements. The use of full spheres is particularly simple and cost-effective with considerable reliability and closing stability. However, other shapes of closure elements are also possible as described and may be advantageous for certain applications. The embodiments outlined should therefore only illustrate the invention, but in no way restrict the general inventive concept defined in the attached patent claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 100 50 085.4 | Oct 2000 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP01/09016 | 8/3/2001 | WO | 4/10/2003 |
