The invention relates to a temperature-control device for receiving of laboratory vessels in order to keep the content of the laboratory vessels at a prescribed temperature over a prolonged period.
International Patent Application Publication WO92/12071A1 and corresponding U.S. Pat. No. 5,181,394 disclose a storage and transport device for thermally sensitive products. The device described is intended to store particularly biologically active substances within a defined temperature range in a state that is cooled but not frozen. To that end, a container carrier of the device has depressions for glass ampoules with the substances that are comprised therein and are to be protected. The container carrier is produced from thermoplastic material and forms a self-contained space around the depressions and around a hollow peripheral edge region extending beyond the depressions. Within the self-contained space extending to the level of the depressions there is a temperature-control medium which has a high enthalpy of fusion and which changes its physical state. Water or gel materials can be used as temperature-control medium for this purpose. The hollow edge region serves for the expansion of the temperature-control medium as it undergoes phase change.
The above device has the disadvantage that, during the thermal conditioning of the device, the phase change of the temperature-control medium begins at the external side of the hollow space, and the greatest volume expansion occurs in the region where the phase change is most delayed. Because the hollow air-filled space encompasses only the edge region, deformation occurs in the center of the container carrier, whereupon the depressions are no longer located at identical height in relation to the base of the container carrier. The correct geometry is not regained until the opposite phase change takes place.
In the absence of permanent correct geometry, it is not possible to use the above type of container carrier in automated laboratory equipment for the handling of the substances in the glass ampoules or in other vessels. Deformation of the container carrier can also give rise to errors during the manual handling of a plurality of substances in adjacent depressions.
Another disadvantage with this type of container carrier is that the opposite phase change does not proceed in a uniform manner: it begins in the edge region of the hollow space and ends in the center of the container carrier. It is not possible to maintain a prescribed temperature over a required period in every depression. Furthermore, during the phase change the enthalpy of fusion is not utilized consistently and distributed across all the depressions.
European Patent Application Publication EP2428273A1 and corresponding U.S. Patent Application Publication 2012/0085181A1 disclose a temperature-control device for sample vessels in a non-autonomous design. This temperature-control device has two temperature zones which are insulated from one another for sectional heating and cooling of the sample vessels. The desired temperature is set by means of a heating element in the first temperature-control zone and by using through-flow of a heat-transfer medium in the second temperature-control zone. The temperature-control device therefore requires connections to electrical and thermal energy and is complex in relation to construction and to the number of functional elements.
The invention is based on the object of providing a temperature-control device which is intended for receiving of laboratory vessels of the type mentioned in the introduction and which keeps the content of the laboratory vessels at a prescribed temperature across, as far as possible, the entire receiving area for a prolonged period without introduction or withdrawal of thermal energy, and which is also functionally improved by virtue of its good thermal dimensional stability that can be produced at relatively low cost.
The object is achieved via a temperature-control device of the type and a temperature-control process for laboratory vessels as disclosed herein below.
In the invention, a temperature-control device for receiving of laboratory vessels has a hollow housing comprising an internal region and comprising a temperature-control medium. The temperature-control device is thermally conditioned before use thereof in the absence of laboratory vessels. During use thereof, in a finite time period, the temperature-control device either absorbs the conditioned thermal energy, i.e., heat, from the laboratory vessels or transfers said energy to the laboratory vessels. To this end, the lower part of the housing has a base, and its upper part, opposite to the base, has a receiving region which delimits the hollow internal region of the housing in upward direction. On the upper side of the receiving region, depressions directed inward serve as receivers for the laboratory vessels to be temperature-controlled.
It is preferable that the hollow housing has, alongside the internal region that accepts the temperature-control medium, a separate air space. In an alternative format, the internal region can have a partition that divides the internal region into compartments, in particular a first internal region and a second internal region. The ultimately decisive factor is that the structural design of the housing separates the air space from the temperature-control medium, i.e. that at least substantially no mixing of air space and temperature-control medium takes place. This can in particular be achieved via an appropriate component, for example, a partition. The invention moreover also allows a design in which the internal space of the housing comprises only the temperature-control medium and air, wherein the air present ultimately forms the air space for the purposes of the invention. In particular, here, a boundary is configured between the temperature-control medium and the air space.
Arranged in the internal region of the hollow housing is an absorber element which extends horizontally in the internal region and around which, and/or through which, the temperature-control medium flows. The absorber element is connected in thermally conductive manner to the receiving region. The laboratory vessels inserted into the depressions are thus kept at a constant temperature over a prolonged period by the temperature-control medium. The absorber element is in particular configured as plate.
For the purposes of the present invention, a material or a component is regarded as “thermally conductive” if its thermal conductivity is on average at least 5 W/(m·K).
The enthalpy of fusion of the temperature-control medium is absorbed by the absorber element and transported uniformly to the receiving region. The absorber element extending horizontally in the temperature-control medium permits full utilization of the thermal energy of the material of the temperature-control medium. During the thermal conditioning of the temperature-control device, the absorber element also accelerates transport of heat from the environment by way of the receiving region into the temperature-control medium. The conditioning time is shorter. “Horizontal” extension here is based on the orientation of the temperature-control device during use, and means that the absorber element extends at least substantially perpendicularly to the action of gravity. An arrangement also included here is an embodiment in which the absorber element is not parallel to the base.
In a preferred construction, the internal region of the housing is partitioned parallel to the base. The air space can advantageously be arranged opposite to the receiving region, while that part of the internal region that is adjacent to the receiving region accepts, or comprises, the temperature-control medium. Direct contact and heat exchange between the temperature-control medium and the absorber element and the receiving region is thus permitted.
In another preferred construction, there is a partition arranged between the internal regions of the housing. The partition seals the two internal regions from one another, and is flexible. The partition permits change of volume of the temperature-control medium in the dimensionally stable housing. The flexibility of the partition is achieved via the use of an elastic material, for example, silicone. The elasticity of the partition improves direct contact of the temperature-control medium with the absorber element and with the receiving region.
For the purposes of the invention, a material or component is “flexible” if it has sufficient elasticity to revert to its original shape after deformation by the forces acting on the material or component as a consequence of a change of volume of the temperature-control media during phase change. The spring rate of a material or component that is in particular suitable, for example, a partition, can be below 5 N/mm per mm2. The area used in the calculation here is that area of the component onto which a corresponding pressure is exerted.
In one embodiment, the temperature-control device can be utilized for cooling or for maintaining a temperature above ambient temperature. To this end, the housing with the temperature-control medium is heated or cooled, while preferably the temperature-control medium changes its physical state and the energy relating to the phase change is utilized.
A low-cost method uses, as temperature-control medium, water or an aqueous solution which freezes on cooling.
In an advantageous embodiment, the temperature-control medium has a lower or higher density in solid phase than in its liquid phase. During phase, proceeding from the outside, the temperature-control medium that is still solid can float or sink in the temperature-control medium that has already to some extent resumed its liquid state. By virtue of the different densities here, the solid temperature-control medium moves forcibly toward the absorber element. The thermal energy of the receiving region, with the inserted laboratory vessels, is in particular altered via the contact of the solid temperature-control medium with the absorber element, the thermally conductive linkage of this element to the receiving region, and the transfer of heat. If the heat is transferred from the absorber element to the receiving region, the thermal energy of the receiving region is then increased and the laboratory vessels are heated. If the heat is transferred from the receiving region to the absorber element, the thermal energy of the receiving regions is then reduced, and the laboratory vessels are cooled.
The heat that transfers from or to the receiving region is uniform and sufficient. The constant temperature of the temperature-control medium during phase change can be utilized over a prolonged period, and the laboratory vessels can be kept at a certain temperature defined by the intrinsic physical nature of the temperature-control medium. During the preceding conditioning, the phase change from liquid to solid takes place simultaneously on almost the entire surface of the absorber element located in the temperature-control medium, rather than merely at individual locations in the center of receiving region.
A preferred design has the absorber element arranged with spatial separation from the receiving region. It is possible here that the absorber element is designed as a plate and that the absorber element is connected to the receiving region by means of one or more thermally conductive spacer elements. In advantageous design, the plate and spacer elements, and the receiving region, is made of a material with a thermal conductivity of at least 10 W/(m·K), i.e., 10 watts per meter-Kelvin. With this minimum value it is possible to ensure complete absorption of heat by the absorber element or the plate and control of the laboratory vessels to a uniform temperature with simultaneous heat transfer to the temperature-control medium.
In another preferred design, the receiving region of the housing is designed as separate part. This permits reduced heat transfer from the housing and, respectively, advantageously permits design of the receiving region from a material with a relatively high thermal conductivity of at least 100 W/(m·K). In this context, aluminum is a cost-efficient and dimensionally stable material that has excellent machining properties. The other parts of the hollow housing here can be made of a material with a substantially lower thermal conductivity of at most 1 W/(m·K).
Specifically, when a temperature-control medium is used whose density and/or volume can change during phase change of its physical state, the air space over the temperature-control medium serves for volume composition and restricts the increase of pressure on the housing and on the receiving region. In the temperature-control device of the invention, the absorber element, the underside of which is directed toward the base, and/or which takes the form of plate, extends into the temperature-control medium. The absorber element in the invention can be deformed flexibly or elastically in the direction of the receiving region. It is preferable that the absorber element has an area-based spring rate below 1 N/mm per mm2 of area of the underside of the absorber element, or is retained in a manner that provides a spring rate below 1 N/mm per mm2 of area of the underside of the absorber element.
The absorber element is designed either as a plate or, in an alternative design, as a structured, elastic molding, the plate or else the molding being preferably additionally retained in resilient manner on the receiving region by spacer elements. Both variants of a temperature-control device are not adversely affected during the phase change and also permit a volume change of the temperature-control medium in the solid state without loss of their function or deformation of the housing.
Other preferred embodiments of the temperature-control device of the invention will be apparent from the description below in conjunction with the accompanying drawings.
The temperature-control device 1 shown in
Configured on the receiving region 3.1 are depressions 5 which are directed from above in the direction of the base 3.2 and inward, and which serve as receivers for the laboratory vessels 2 that are to be temperature-controlled. The base 3.2 can be dimensioned in SBS (Society of Biomolecular Screening) format, and the number of depressions 5 can be arranged in the SBS standard array: 12×8, 24×16, etc.
The temperature-control device 1 can, while standing on the base 3.2 or lying on the depressions 5, in each case before use of said device with laboratory vessels 2, be thermally conditioned, i.e., heated or cooled, in order to assume a certain temperature differing from the usage environment.
In an advantageous design, arranged between the hollow internal regions or the base 3.2 and the housing 3 is a partition 3.3 which seals the two internal regions from one another and is flexible. The partition 3.3 can also be arranged within other parts of the housing 3. The design in
In the design in
The temperature-control device 1 in
The absorber element 7 can have one or more apertures 7.1 which permit through-flow of air bubbles and, with appropriate size of the aperture 7.1 and appropriate viscosity of the temperature-control medium 4, at least partial flow of the temperature-control medium 4 through the absorber element 7.
The absorber element 7 is connected to the receiving region 3.1 in a manner that provides good thermal conductivity for the transfer of thermal energy, and thus transfers the temperature of the temperature-control medium 4 to the laboratory vessels 2.
The temperature-control device 1 of the invention is exposed, before use thereof, to the desired temperature for a sufficient time. The housing with the temperature-control medium 4 of the temperature-control device 1 is heated or cooled, in accordance with the temperature range required by the substances in the laboratory vessels 2.
The temperature-control medium 4 used in the housing 3 changes its physical state during heating or cooling. During cooling, the temperature-control medium 4 freezes, and during heating it melts. The energy of the phase change (by way of example, in the case of water: 333.4 kJ/kg at 0° C.) is effectively utilized here.
Low-cost temperature-control medium 4 preferably used for the cooling of the laboratory vessels 2 is water, an aqueous solution, a glycol/water mixture and/or a gel material, in particular an aqueous carboxymethylcellulose gel. Alternatively, before the heating of laboratory vessels 2 or for keeping these at a temperature above ambient temperature, a mixture of cyclodextrin and 4-methylpyridine is used as temperature-control medium 4. It is also possible to use a polymer solution made of a plurality of soluble substances with different phase temperatures and with a concentration-dependent miscibility gap, for example, a phenol/water mixture.
The temperature-control device 1 in
The temperature-control device 1 shown in
In the design in
The effectiveness of the design of the invention in
Improvements provided by the design in
In the case of the particularly preferred embodiment shown in
The increase in volume of the solid or frozen temperature-control medium 4 is permitted by the expansion of the pretensioned partition 3.3 into the air space 6. The solid temperature-control medium 4 here is forced toward the absorber element 7. The applied pressure increases the transfer of heat during use of the temperature-control device 1, and the temperature profile “B” is kept under the temperature limit for an even longer time. This effect lasts even longer if the partition 3.3 also has low thermal conductivity.
Another decisive factor in the design of the invention in
A preferred design has the receiving region 3.1 of the housing 3 formed as a separate part. The receiving region 3.1 is not coherently connected to the housing 3, and consists of a material with a thermal conductivity of at least 100 W/(m·K). In particular, aluminum is used as suitable material. The other parts of the hollow housing 3 can consist of plastic or can comprise a plastic, and preferably have a thermal conductivity of at most 1 W/(m·K), and thus a more thermally insulating effect.
The structure of the housing 3 here can have even more discrete elements. In
In another preferred design of the temperature-control device 1, the absorber element 7 with its absorber underside directed toward the base 3.2 is configured to be flexible in the direction of the receiving region 3.1. The absorber element 7 tolerates the change in volume of the temperature-control medium 4. In preferred design, the absorber element 7 is a structured elastic molding 7′, as shown in
The molding 7′ shown in
In the design of a plate with spacer elements 8, the spacer elements 8 hold the plate in flexible manner, with a springing effect, in relation to the receiving region 3.1. As shown in
It is moreover preferable that connection of the absorber element 7 on the receiving region 3.1 is releasable or non-releasable. In
Incisions, not shown, provide freedom to the spacer element 8′ and permit undulant bending as shown in
Number | Date | Country | Kind |
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10 2018 005 582.6 | Jul 2018 | DE | national |
10 2018 008 152.5 | Oct 2018 | DE | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2019/069105 | 7/16/2019 | WO |
Publishing Document | Publishing Date | Country | Kind |
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WO2020/016219 | 1/23/2020 | WO | A |
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Number | Date | Country | |
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20220212195 A1 | Jul 2022 | US |