EP2748545A2

EP2748545A2 - An apparatus for freezing and storage of organic material and a door module for such an apparatus

Info

Publication number: EP2748545A2
Application number: EP12756081.1A
Authority: EP
Inventors: Hans-Christoph Paul
Original assignee: HCP Innovation APS
Current assignee: HCP INNOVATION APS
Priority date: 2011-09-06
Filing date: 2012-08-30
Publication date: 2014-07-02
Anticipated expiration: 2032-08-30
Also published as: WO2013034156A3; DK177376B1; EP2748545C0; EP2748545B8; EP2748545B1; WO2013034156A9; WO2013034156A2

Abstract

An apparatus for freezing and storage of organic material according to the invention comprises an internal conveyor system for transporting stored portions of material inside the apparatus, an insulated shell, a primary door facing the exterior and a secondary door facing the interior. The doors, which may be provided in a separate door module, opens to a limited number of the stored portions, and are arranged so that portions of material can be deposited into or removed from the apparatus only when they are both open at the same time. The primary and secondary doors are coupled such that the when the primary door is opened or closed, the secondary door is also opened or closed in a substantially synchronous manner. The doors may be top-hung swing doors and the primary door preferably opens inwards.

Description

An apparatus for freezing and storage of organic material and a door module for such an apparatus

The present invention relates to an apparatus for freezing and storage of organic material, said apparatus comprising an internal conveyor system for transporting stored portions of material inside the apparatus, an insulated shell, a primary door in the shell facing the exterior of the apparatus and a secondary door in the shell facing the interior of the apparatus, where the secondary door opens to a limited number of the stored portions, and where the primary door and the secondary door are arranged so that portions of material can be deposited into or removed from the apparatus only when the primary door and the secondary door are open at the same time. The invention also relates to a door module for such an apparatus and to the use thereof.

In order to successfully preserve biomolecules, cells and biological tissue for extended periods of time, storage below -80 degrees Cel- cius (C°) is generally required. However, both shelf life and the ability to recover living cells are dramatically improved at even lower temperatures down to about -196C°, which is the boiling point of liquid nitrogen. Therefore, liquid nitrogen is often used as a cooling agent for preservation of organic material, even though it is a very expensive substance.

Freezers operating at such low temperatures are generally known as cryogenic freezers, and the material stored therein is said to be cryo- preserved. There are different opinions on the upper tempera- ture limit below which the term "cryogenic" should be applied to temperatures. The American National Institute of Standards and Technology has suggested an upper limit of -150C°, while some scientists regard the boiling point of oxygen (-183C⁰) as the upper limit. However, it is generally agreed, that a freezer refers to a storage device that operates from about -5C° to -20C°, an ultra low freezer operates from about - 50C° to -90C°, and a cryogenic freezer operates from about -140C° to - 196C°. Whenever the term "freezer" is used in the following it is to be understood that reference is made to an apparatus capable of operating as a cryogenic freezer. Hospitals, laboratories and research institutes all over the world experience an ever increasing need to be able to cryo- preserve, store and handle different types of organic material, and many hospitals have storage systems for frozen and cryo- preserved material spread around in many different departments. Such use of a number of relatively small storage systems is not very efficient, neither when it comes to the space occupied by the many systems, nor when regarding the energy consumed to keep the stored material at sufficiently low temperatures.

Many storage systems are arranged as ordinary laboratory freezers, where conta iners a re stored in front of and on top of each other in order to maximize the use of the available space within the apparatus. Here, the apparatus door often has to be kept open for an extended period of time while the desired sample container is found and the interior temperature of the apparatus increases temporarily. Not only is it energy consuming to bring back the interior temperature to a desired level, the samples of material stored near the door may also degrade due to repeated warming and refreezing.

An example of a cryogenic freezer, where the use of liquid nitrogen and the warming of stored material, have been minimized, is known from WO2008/083685. In this apparatus, a series of boxes for housing stored material is arranged in a paternoster system, and the insulating shell is provided with double doors, which open to only one or a few boxes at a time. When having to deposit or remove material from the freezer the paternoster is simple turned until the relevant box is op- posite the doors and the doors are then opened only for as long as it takes to handle the relevant portions of material. This works very well in terms of achieving good insulating properties when the doors are closed, but there is still a considerable thermal loss when the doors are opened and the system can only be operated by a human operator.

It is therefore the object of the present invention to provide an apparatus, where the temperature inside can be kept even more constant and which can be operated by automated storage and retrieval systems.

This object is achieved with an apparatus, where the primary door and the secondary door are coupled such that the when the primary door is opened or closed, the secondary door is also opened or closed in a substantially synchronous manner. The synchronous movement of the doors minimizes the time, where an opening is present in the insulating shell, since the primary door does no longer has to be left open, while the secondary door is being opened or closed. In addition, the coupling of the doors allows them to be operated by an automated system or robot, which, on average, works faster and more focused than a human operator. Still another advantage is that the risk of forgetting to close one of the doors is minimized since one will always follow the other. All of these factors contribute to a reduced thermal loss and hence to the temperature inside the apparatus being less affected. This not only means that the material inside deteriorates more slowly; it also means a reduction of the energy needed for running the apparatus.

It is noted that the term "synchronous" is intended to mean a substantially simultaneous movement of the two doors, where their respective patterns of the movement may or may not be identical. An example of identical but mirror- inverted patterns of movement will be given below. Moreover, the movement of one door may be slightly de- layed in relation to the other, for example to prevent the doors from colliding, as long as the main part of their opening and closing intervals overlap.

In a preferred embodiment, the insulated shell comprises an outer wall and an inner wall, where the primary door is arranged in the outer wall and the secondary door is arranged in the inner wall, and where each door has insulating properties corresponding substantially to those of the wall in which it is arranged. Doors arranged in door modules are preferably embodied in the same way, the doors being arranged in walls of the door module corresponding to the inner and outer walls of the insulated shell. In this way the insulating properties of the insulated shell is substantially continuous in the closed state of the doors, which minimizes the risk of the formation of thermal bridges and other unde- sired thermal gradients.

As the inner and outer walls may advantageously be of similar design, this may result in the primary and secondary doors also being very similar with regards to insulating properties, and as the doors are designed to work synchronously, it may also be advantageous to make them with substantially the same dimensions. The result may therefore be doors that are substantially identical and even though an aesthetically pleasing design and wear-proof surface layer is normally only needed on the outer side of the primary door, it is imaginable to use the same design for the secondary door. This will reduce production costs and the number of parts to be kept on stock.

In a preferred embodiment, both doors are swing doors, where at least one of the doors is preferably top-hung to pivot about a substantially horizontal axis during opening and closing. This allows easy opening by external force, either manual, automated or robotic, particularly when the primary door opens inwards, since access to the interior of the freezer can then be gained by simply pushing on the primary door. Bottom-hung or side-hung doors may, however, also be employed.

The secondary door preferably opens outwards, i.e. away from the interior of the apparatus and into the lumen of the insulating shell or door module. This means that it does not take valuable room inside the freezer compartment and that the risk of the mechanism blocking due to the low temperature is minimised.

As in WO2008/083685, the content of which is hereby incorporated by reference, cassettes may be used for housing portions of material, in order to enable the users of the system to organize and arrange different stored portions of material that are related to each other in an orderly manner. Also, the use of cassettes enables storage of portions of different sizes and dimensions and the requirement for packaging of the individual portions can be loosened.

If using such cassettes, the size and shape of the doors of the apparatus should preferably be adapted to fit the size and shape of the cassettes, the primary and secondary doors having substantially the same width as the width of one or a multiple of cassettes. A certain over-size will, however, be required to allow handling of the cassettes, manual handling usually requiring a larger over-size than automated or robotic handling. Over-sizes of between 2 mm and 80 mm, preferably between 5 mm and 50 mm and still more preferred about 25 mm for manual handling may be employed.

The skilled person will be able to device several ways of achiev- ing the actual synchronous operation of the doors, including the use of electronically controlled activators. At present it is, however, preferred that the primary and secondary doors are interconnected by a mechanical system, which transmits a force applied to the primary door to the secondary door in the form of a push or pull thereon. Such a system, an embodiment of which will be described below, is relatively insensitive to the low temperatures encountered in the apparatus according to the invention and may be easily maintained and repaired when needed.

Preferably a series of primary doors and a series of secondary doors extend in two respective parallel rows across the width of the ap- paratus to give easy access to all areas of the interior of the apparatus. It is of course also possible to provide a system for lateral movement of portions of material and/or cassettes inside the apparatus, possibly even in a space between the primary and secondary doors. At present such a system is, however, less preferred as the running of complex moving systems at cryogenic temperatures is a difficult task.

When having two or more doors arranged in series, it is of course possible to provide for the possibility of opening two or more neighbouring doors at the same time so that they form one larger opening, and/or to provide doors of different sizes.

It is noted that the term "door" is also intended to include doors comprising two or more parts that open together as is known for example from elevator doors.

As in WO2008/083685 the apparatus may include boxes arranged in a paternoster system to receive and house the portions or cassettes during storage, but, as mentioned above, this system should be relatively simple to avoid down-time.

As the apparatus according to the invention will often be made in relatively large sizes it may advantageously be constructed and manufactured in two or more modules adapted to be combined with each other to form the complete apparatus on the use-site. If possible, each of these modules should be made with dimensions small enough for it to pass through standard door openings or fit into a standard truck or cargo-container.

As will be understood from the above, the present invention is concerned with the improvement of the doors of the apparatus, whereas the rest of the apparatus may in principle be embodied as described in WO2008/083685. Accordingly, a new door module may be used for transforming a prior art apparatus into one according to the invention. Such a door module is therefore also considered as part of the invention.

Any suitable material, such as a plastic material may be used for the wall(s) of the insulated shell. It is, however, preferred that they comprise at least one layer of vacuum panels enclosed by at least one layer of fibrous material, such as fibreglass. A space between the walls may advantageously contain insulating foam, such as polyurethane or polystyrene foam, and/or the air pressure in a space between the walls can be kept higher than the air pressure outside said insulated shell to avoid thermal loss by the ingress of warmer air from outside. For similar reasons, the air pressure in the interior of the apparatus, i.e. on the in- side of the inner wall, is preferably higher than the air pressure outside said insulated shell. An even better prevention of the an air exchange is, however, achieved by providing at least one gas inlet for establishing a gas flow between the primary door and the secondary door in a direction substantially in parallel to the doors when in a closed state. Such a gas flow, which may be led in the right direction by providing an outlet with active suction, functions as an air curtain between the doors and the gas should preferably be cold and dry.

The apparatus according to the invention may in principle be used at any temperature below the freezing point, but it is preferred that it is arranged for operating at or below about -170 degrees Celcius. This temperature may be reached if the apparatus is cooled by vaporization of liquid nitrogen, having its boiling point at -196C°.

Examples of organic material that may be stored in the apparatus according to the invention could be tissue samples, such as biopsies or scraps of skin stored for later analysis, or half-litre portions of human blood stored for use in connection with a surgical operation or the like. The apparatus may, however, be used for freezing and storage of any portions of blood or tissue of human or animal origin as well as any other material, which is to be cryo- preserved.

In the following preferred embodiments of the invention will be described with reference to the drawing, where

Fig. 1 is a perspective view of an apparatus according to the invention,

Fig. 2 is a perspective view of a door module,

Fig. 3 is a cross-sectional view of another door module with doors in a closed and in a semi-open position, and

Fig. 4 corresponds to Fig. 3 but with the doors in a closed and in a fully open position.

An apparatus 1 for freezing and storage of portions of organic material is shown in Fig. 1. It comprises an insulated shell 2 in which a primary door 3 is positioned for providing access to the interior of the apparatus 1.

The apparatus may contain a plurality of boxes connected to- gether to form an endless chain or paternoster and being part of an internal conveyor system, just as in the apparatus known from WO2008/083685. The conveyor system is preferably driven by an external motor (not shown) via a drive axle entering the apparatus through the insulated shell 2. In this way any heat generated by the motor will not have to be compensated for within the apparatus, but some thermal loss is unavoidable since the axle lead-in will necessitate an interruption of the insulated shell and the axle itself potentially forms a thermal bridge.

A cooling tank (not shown) containing a cooling agent, prefera- bly liquid nitrogen, is preferably placed in the centre of the apparatus 1 to keep it cool and save energy. The tank is preferably enclosed by the endless chain formed by the conveyor system, so that it does not take up space that could otherwise have been used for storage of portions of organic material. The apparatus is meant to be installed in laboratories, hospitals etc., preferably with a minimum of special installations. It is therefore preferably made to work with standard line voltage and frequency, typically 220 V and 50 Hz in Europe, and made primarily from lightweight materials in order to minimize the load on the supporting structure of the building. Moreover, all interior parts of the apparatus 1 should preferably be made from materials that are stable at cryogenic temperatures at least down to about -170C°. This is for example achieved by using self-lubricating materials for moving parts, which also reduces the need for cleaning and maintenance.

The insulated shell preferably comprises an inner wall and an outer wall with a shell space between them (not shown), insulating foam, preferably polyurethane, preferably being provided in the shell space. The walls may each comprise one or more layers of fibreglass and one or more layers of vacuum panels and both walls may be divided in an upper part and a bottom part (not shown), which are bolted together. In this way each wall may be formed from two bowl-shaped shells and if the apparatus needs to be disassembled, for example for maintenance purposes, the two upper shells may be simply lifted off.

As may be seen, the apparatus 1 shown in Fig. 1 is assembled from two modules, namely a door module 4 and a freezer compartment module 5, but it is to be understood that a division into smaller modules is also possible. This, however, requires extra care during assembly to make sure that thermal bridges are not formed at the joints between modules. The division into modules not only allows easy transportation and assembly; it also provides for the opportunity of replacing only a single module for maintenance or repair while leaving the rest in place.

An embodiment of a door module 40 is shown in Fig. 2. As may be seen, this module comprises a series of eight primary doors 41 and a corresponding num ber of secondary doors 42 are found on the other side of the module, only a few of these being visible from the inner side in Fig. 2. As for the insulated shell, the door module too comprises an outer wall 401 and an inner wall 402 with a space 403 between them, and even though shown empty in Fig. 2, this space too may be filled with an insulating material such as polyurethane foam, expanded polystyrene or mineral wool.

Each primary door is interconnect to a secondary door via a linkage mechanism 43 as will be explained in detail later, so that they open together, but the primary doors are independent of each other. If making the door module without posts between the individual door openings, it is, however, possible that two or more primary doors may be opened at the same time, thus forming one larger door opening.

Horizontal plates 44, 45 are provided just below and above the door openings spanning the width and length of the door module, so that a compartment is formed between the primary and secondary doors. This provides stiffness and stability to the door module and allows the air flow at the doors to be controlled as will be explained below. In addition, the lowermost plate 44 may serve as a support surface for objects being inserted into the apparatus and/or prevent them from being dropped into the space below. The plates may be in the form of grids or like materials/structures with openings.

At the top and bottom the width Wi of the door module corresponds substantially to the thickness of the insulated shell and at the centre section the width W₂ is approximately doubled. This increased width has two purposes.

Firstly, as may be seen from Figs. 3 and 4, which show a slightly different embodiment than Fig. 2, it allows the primary 141 and secondary 142 doors to be swung upwards and into the module 140 without colliding, and, secondly, is contributes to minimizing the thermal loss occurring during opening and closing of the doors.

Turning first to Fig. 3 the doors are shown with one set 141, 142 in a semi-open position and another 141', 142' in a closed position, further sets potentially being hidden behind these. As may be seen, the linkage mechanism 143 interconnecting the two doors 141, 142 comprises two elongate brackets 431, 432 each having a longitudinal slit. A bolt 433 penetrating through both slits interconnects the two brackets, but allows them to move in relation to each other. When the primary door 141 is opened, the arm 434 swings as indicated by the double ar- row P and the elongate bracket 431 is forced inwards and upwards. This causes the elongate bracket 432 on the secondary door 142 to also be forced upwards and since this too is provided with an arm 435, which swings as indicated by the double arrow S, the secondary door is caused to open.

In Fig. 4 the doors 141,142 are shown in the fully open position and it may be seen that the height of the doors are such that they meet at the middle in the fully open position. This need not be the case, but has the advantage that the door module and hence the distance which has to be covered to insert an object into the apparatus is kept at a minimum. It would of course also be possible to let the two doors overlap in the open position, but that would necessitate a different opening mechanism. More complex mechanisms, including hydraulic or pneumatic solutions, for opening and closing the doors are of course imagin- able, but the more complex the bigger the risk of failure, e.g. because of the mechanism freezing.

The primary and secondary doors are preferably made with substantially the same insulating properties as the outer and inner walls of the door module, respectively, possibly even from the same material, and in the embodiment of Figs. 3 and 4 they are entirely identical.

In the embodiment shown in Figs. 3 and 4 the doors are arranged as part of an opening module 146, which is connected to the rest of the door module 140 by means of bolts 147. As may be seen, the top 145 of the opening module is here slightly inclined in order to make it easier to insert it into the door module. This not only eases the initial assembly, but also facilitates a replacement in case of malfunction.

The door module in Figs. 3 and 4 further comprises a gas inlet pipe 149 and a gas outlet pipe 150 for supplying gas, preferably air, to the system and extracting it as indicated by the arrows A in Fig. 3. It is to be understood that the pipes are T-shaped with a horizontal part

491.501 running along the length of the door module and the openings

492.502 being either a longitudinal slit or a series of openings in the length direction. Blowers or suction means (not shown) may be used for forcing the gas through the system. This gas or air flow A creates what may be described as an air curtain in the door module, which to a large degree prevents an air flow in the horizontal direction and hence an exchange of air between the interior of the apparatus and the exterior. In other words, the curtain keeps the cold air inside and the warm ambient air outside. The air curtain is most important when the doors are open, but a permanent flow of cold air may compensate for the lack of insulating material between the doors.

When the doors are open as shown in Fig. 4 they will of course obstruct the air flow, but as neighbouring doors will usually be in the closed non-obstructing state, this will simply result in the air flow bypassing the open doors on the sides thereof.

Any type of air or gas may in principle be used for this purpose, but it should preferably be cold and dry, and air conditioning equipment (not shown) may be provided for this purpose. It may also be advantageous to utilise the cooling capacity of the nitrogen on its way out of the system.

It is also preferred to keep the air pressures in the shell space 403 and in the interior of the apparatus 1 higher than the pressure out- side the shell 2. This assures that the gaseous nitrogen 42 flows in the right direction and significantly reduces the amount of air at ambient temperature that enters the inner space 41 of the apparatus 1. Preferably, the pressure in the interior of the apparatus is higher than in the shell space.

The apparatus may be connected to a computer used for registration of portions of material to be stored within the apparatus and automating storage, search of and/or access to individual portions of material stored within the apparatus. For this purpose the individual portions and/or cassettes may be provided with barcodes, RFID tags or the like and corresponding scanners be arranged at or integrated in the apparatus or door module according to the invention.

The same or a separate computer may also be used for controlling the operation of the apparatus, such as the movement of the internal conveyor system and the regulation of temperature. The embodiments of invention described above comprise a number of features, which may be combined in different ways without departing from the scope of the invention as defined in the claims. As an example, the door opening mechanism in Figs. 2, 3 and 4 may also be used on an apparatus having only a single door as in Fig. 1 and/or the ventilation pipes of Figs. 3 and 4 might be used on the apparatuses in Figs. 1 and 2.

Claims

P A T E N T C L A I M S

1. An apparatus for freezing and storage of organic material, said apparatus comprising an internal conveyor system for transporting stored portions of material inside the apparatus, an insulated shell, a primary door in the shell facing the exterior of the apparatus and a secondary door in the shell facing the interior of the apparatus, where the secondary door opens to a limited number of the stored portions, and where the primary door and the secondary door are arranged so that portions of material can be deposited into or removed from the appara- tus only when the primary door and the secondary door are open at the same time, c h a r a c t e r i z e d in that the primary door and the secondary door are coupled such that the when the primary door is opened or closed, the secondary door is also opened or closed in a substantially synchronous manner.

2. An apparatus according to claim 1, where the insulated shell comprises an outer wall and an inner wall, where the primary door is arranged in the outer wall and the secondary door is arranged in the inner wall, and where each door has insulating properties corresponding substantially to those of the wall in which it is arranged.

3. An apparatus according to claim 1 or 2, where the primary and secondary doors are substantially identical.

4. An apparatus according to any of the preceding claims, where both doors are swing doors, at least one of the doors preferably being top-hung to pivot about a substantially horizontal axis during opening and closing.

5. An apparatus according to any of the preceding claims, where the primary door opens inwards.

6. An apparatus according to any of the preceding claims, where the primary and secondary doors are interconnected by a mechanical system, which transmits a force applied to the primary door to the secondary door in the form of a push or pull thereon.

7. An apparatus according to any of the preceding claims, where a series of primary doors and a series of secondary doors extend in two respective parallel rows across the width of the apparatus.

8. An apparatus according to any of the preceding claims, where at least one gas inlet is provided for establishing a gas flow between the primary door and the secondary door in a direction substantially in parallel to the doors when in a closed state.

9. Apparatus according to any of the preceding claims being constructed and manufactured in two or more modules adapted to be combined with each other to form the complete apparatus on the use- site, each module preferably having dimensions small enough for it to pass through standard door openings.

10. A door module for use in an apparatus according to any of claims 1-9, said door module comprising a primary door intended to face the exterior of the apparatus and a secondary door intended to face the interior of the apparatus, where the primary door and the secondary door are coupled such that the when the primary door is opened or closed, the secondary door is also opened or closed in a substantially synchronous manner, and further comprising means for interconnection to the insulated shell of the apparatus.