Patent Description:
Cryopreservation is a technique used for the preservation of biological samples that involves cooling samples to, and maintaining them for prolonged periods at, very low temperatures, for example -<NUM> to -<NUM>. By cooling a biological sample to a low temperature, the kinetics of chemical or enzymatic reactions that would otherwise degrade the sample are slowed to such an extent that the sample no longer degrades or only degrades at a very slow rate. As a result, biological samples can be stored over prolonged periods and then brought back to ambient temperature as required for use and/or analysis. See, for example, <CIT>, which discloses a container comprising: an insulated housing comprising a cavity for containing one or more cryopreserved biological samples; a sealed space that surrounds the cavity and comprises liquid nitrogen; and a heat transfer engine.

Cryopreserved samples can be transported if their temperature is maintained at a sufficiently low temperature during transit. If the sample is allowed to warm above a certain temperature, for example above the glass transition point of the sample, the integrity of the sample can be compromised. This is because the cryoprotective agents used in the cryopreservation process have a degree of toxicity towards the sample and more diffusion and therefore more chemical reactions can occur which can affect the viability of the stored cells. Prolonged exposure to the cryoprotective agents and chemical reactions at higher temperatures and their cumulative effects causes damage to the cryopreserved material. Below the glass transition temperature the viscosity of the system means that cumulative effects are very small. During cryopreservation cooling from the cell's ambient temperature needs to be done in a controlled way to minimise damage and optimise cell viability post thaw. It is therefore evident that to ensure sample integrity in shipping the cryopreserved sample must be kept cold enough for the cumulative damaging effects not to be significant in the anticipated period of transportation and storage.

In addition to the need to maintain an adequately low temperature during transit the shipping container and its contents must be compatible with the environments it passes through before, during and after transit. Thus, in the case of airfreight it is unacceptable on safety grounds for a phase transition coolant such as liquid nitrogen to be used if there is a risk of spillage of the liquid nitrogen. To circumvent this problem, dry shippers, Dewar vessels with porous materials such as molecular sieves or zeolites, have been developed to ensure that low temperature shipping can be achieved without the risk of liquid nitrogen spillage. In such Dewars liquid nitrogen is absorbed into the porous material and is retained therein until it boils off as gaseous nitrogen.

A problem associated with these dry shippers is that the porous materials are easily contaminated, for example with particulate biological material from the liquid nitrogen that remains in the dry shipper must be sterilised between each use and this makes their use in sterile environments such as operating theatres and clean room highly undesirable Additionally, the Dewar vessel is a vacuum jacketed vessel and to ensure equal pressure distribution on the vessel walls the shape of the vessel must be approximately cylindrical or spherical as avoiding catastrophic failure requires thicker materials and therefore poorer performing Dewars. A combination of these factors means that the dry shippers are generally in the form of a cylindrical or spherical Dewar with a relatively narrow aperture at one end through which charging with liquid nitrogen and sample occurs. A typical dry shipper has a bore that projects radially from the central axis of the Dewar's mouth. The porous material in which the liquid nitrogen is absorbed is provided in the ring between the outer wall of the bore and the innermost wall of the Dewar and this dictates that the porous material (i.e. the molecular sieve element) cannot be removed and replaced easily and in any case not without first extracting the sample.

Simpler shipping containers containing a phase transition cooling material such as solid carbon dioxide as the coolant (cryogen) can also be used for shipping cryopreserved samples and consist of an insulated vessel, for example a Dewar or an insulated box, containing the sample on or immersed in a bed of solid carbon dioxide. The problem with such containers is that they are only capable of maintaining the sample at a low temperature for a relatively modest period of time and are unsuitable for shipping or storage over large time scale without frequent recharging of the phase transition cooling material. Solid carbon dioxide has a temperature of approximately - <NUM> which is above the glass transition temperature of many cryoprotective agents and this temperature may not be low enough to prevent damage to the sample before, during, or after transport over longer timescales (days).

Developments in medicine mean that there is a growing need to ship and maintain cryopreserved samples in environments where cryogenic materials (liquid nitrogen, solid carbon dioxide etc.) and storage facilities are not available and/or practical. For example, the field of immunotherapy is rapidly developing and has significant potential for therapy, for example in the treatment of cancers such as leukaemia and melanoma. In one approach T-cells are harvested from a patient's blood and then genetically engineered to introduce chimeric antigen receptors (CARs) on their surface. The resultant chimeric antigen receptor T-cells (CAR T-cells) are then grown up in the lab to provide a sufficient number for therapy and are in turn transfused into the original patient. The CAR T-cells can then recognise the relevant protein antigen on the tumour cell's surface and in turn recruit the patient's immune system to kill those cells. This process requires the transfer of the blood and/or tissue samples to a laboratory capable of performing the genetic engineering thereon and then growing the requisite number of CAR T-cells. In addition, the CAR T-cells must then be shipped back to the patient's own clinic and stored until the patient is ready for treatment. This typically requires storage of the cryopreserved CAR T-cell sample(s) at the clinic for a period of several weeks or more and this demands either construction of a local cryopreservation facility or provision of a shipping container that can also serve as a storage unit on arrival. It is an object of the present invention to provide such a shipping container.

The techniques are diagrammatically illustrated, by way of example, in the accompanying drawings, in which:.

Many types of biological materials are cryopreserved for subsequent application in medicine, biotechnology and veterinary sciences. To ensure long term viability it is considered essential to maintain the samples at temperatures below <NUM>. A convenient way to achieve such low temperatures is by the use of liquid nitrogen (which has a boiling point of <NUM>). Following the addition of cryoprotective additives and controlled rate freezing, samples in specialist cryo-containers are either immersed in liquid nitrogen or in the vapour phase above liquid nitrogen, which is usually contained in a Dewar vessel. The liquid nitrogen evaporates and is replenished with fresh liquid nitrogen, which may be carried out manually or by automated top up systems from large Dewars or storage tanks. As an alternative to liquid nitrogen, mechanical freezers which operate at <NUM> have been developed.

However, a number of problems exist with current cryogenic storage methods. For example, liquid nitrogen is expensive and may be difficult to obtain in some geographical locations. Health and safety issues may arise in relation to the storage and handling of large volumes of liquid nitrogen. Furthermore, following manufacture, liquid nitrogen may contain very low levels of contaminants, and during transport and storage, further contamination may occur. Accordingly, liquid nitrogen must always be considered to be contaminated with viable micro-organisms. Contamination of liquid nitrogen by ice, inanimate debris and viable micro-organisms is documented and a number of reports have demonstrated the transfer of contaminants from liquid nitrogen to its vapour. In principle it is possible to filter liquid nitrogen, however this may require specialist equipment and the filtering procedure may need to be validated to prove that contaminants are removed each time the filtering procedure is performed. If validation is not possible, liquid nitrogen cannot be used in a clean room without compromising the air quality. Further still, to achieve cryogenic temperatures, mechanical freezers conventionally employ cascade compressors, which tend to be large, noisy and expensive.

Broadly speaking, the present techniques relate to containers for cryopreserved biological samples, which comprise a supply of liquified gas for keeping the cryopreserved biological samples at the required temperatures while the samples are being stored and/or shipped. The container described herein comprises a sealed reservoir containing at least a liquified gas, which is used to keep cryopreserved biological samples at the required temperatures but without the liquified gas directly contacting the samples. Evaporation of the liquified gas within the sealed reservoir may be mitigated by providing a means within the container to condense evaporated liquified gas, such that the liquified gas within the sealed reservoir is maintained at a volume required to keep the samples within the container at the required temperature.

Embodiments of the container may advantageously remove or substantially reduce the possibility of the biological samples being contaminated by the liquified gas or by evaporated liquified gas. Furthermore, by providing a sealed reservoir containing a liquified gas within the container, it may be possible to use the same supply of liquified gas for a substantially long time, which solves the problem of not being able to obtain liquified gas in some geographical locations. Further still, as the same supply can be used and reused once it is provided within the sealed reservoir, the health and safety concerns may be reduced, as a user of the container may not need to come into contact with the liquified gas, particularly when placing samples into the container or removing them from the container.

<FIG> shows a schematic diagram of a container <NUM> for storing and/or shipping cryopreserved samples <NUM>, such that the cryopreserved samples within the container <NUM> are maintained at a required temperature for an extended period of time to ensure sample integrity. The cryopreserved samples <NUM> may be cryopreserved biological samples, or any type of samples that require cryogenic storage without the use of conventional cryogenic materials such as liquid nitrogen or solid carbon dioxide.

The container <NUM> comprises an insulated housing comprising a cavity <NUM> for containing at least one cryopreserved biological sample <NUM>, and a sealed reservoir <NUM> at least partly surrounding the cavity <NUM> of the housing. In embodiments, the sealed reservoir <NUM> may comprise liquified gas <NUM>, which is provided in the sealed reservoir from at least one external source (not shown). The liquified gas <NUM> may be any one or more of liquified helium, liquified nitrogen, liquified air, and liquified oxygen, though it will be understood that this is a non-exhaustive and non-limiting list of suitable materials. Additionally or alternatively, the sealed reservoir <NUM> may comprise liquified gas that has been adsorbed into a suitable material.

The sealed reservoir <NUM> comprises at least one valve <NUM>. The at least one valve <NUM> may be a relief valve, pressure relief valve, or safety valve for controlling or limiting the pressure within the sealed reservoir <NUM>. The relief valve may be designed to automatically open when a predetermined pressure is reached within the sealed reservoir <NUM>. The relief valve may be provided in case of failure of mechanism within the container to condense / re-liquify evaporated liquified gas (which may result in gas build-up within the sealed reservoir <NUM>), interruption of power to this mechanism, or failure of the insulation of the container <NUM>.

In embodiments, the at least one valve <NUM> may be, or may comprise, a flow sensor. The flow sensor may be used to determine if gas is entering or leaving the sealed reservoir <NUM>. For example, if gas is determined to leave the sealed reservoir <NUM>, this may indicate a leak either pressure relief is taking place or that there is a leak that is enabling gas to escape the sealed reservoir <NUM> (which may mean that the supply of liquified gas <NUM> needs to be topped-up more frequently). The flow sensor (not shown in <FIG>) may be coupled to a controller, such that if the flow sensor indicates that gas is escaping from the sealed reservoir, the controller can take action to remedy the situation. For example, the controller may cause a cryocooler to switch-on to cool/condense the gas, and thereby reduce or stop the flow of gas out of the sealed reservoir <NUM>. This is described in more detail below.

The at least one valve <NUM> may be an inlet valve for filling the sealed reservoir <NUM> with gas (that will be condensed within the reservoir to provide liquified gas) or with liquified gas <NUM>. Thus, the inlet valve may be couplable to an external source of gas/liquified gas <NUM>, such that the gas/liquified gas can flow into the sealed reservoir <NUM>. In embodiments, the inlet valve may be coupled to at least one sensor <NUM> within the sealed reservoir <NUM>. The at least one sensor <NUM> may be a sensor for sensing a volume of liquified gas <NUM> within the sealed reservoir <NUM>. The inlet valve <NUM> may be configured to automatically close when the at least one sensor <NUM> indicates that the required volume of liquified gas <NUM> has been obtained in the sealed reservoir <NUM>. In embodiments, there may be at least two 'fill sensors' <NUM> in the sealed reservoir <NUM> - one may be used to determine if a minimum required volume of liquified gas <NUM> is present in the sealed reservoir <NUM>, and another may be used to determine if a maximum volume of liquified gas <NUM> is present in the sealed reservoir <NUM>. In such embodiments, the inlet valve <NUM> may remain open until the sensors indicate that a maximum volume of liquified gas <NUM> has been reached.

In embodiments, liquified air may be used in the sealed reservoir <NUM> to keep the samples <NUM> in cavity <NUM> at the required cool temperatures. Liquified air is air that has been cooled to very low temperatures such that it has condensed and become a liquid. Air from the external environment may be pumped into the sealed reservoir <NUM> of container <NUM>, where it is cooled to form liquified air. Air, and liquified air, typically comprises nitrogen, oxygen, argon and other inert gases. Using air or liquified air as the means to provide cooling to the samples <NUM> may be advantageous because a separate, dedicated supply of gas/liquid does not need to be provided to the container <NUM> (e.g. a canister of liquid nitrogen). Instead, air from the environment surrounding the container <NUM> may be input into the container and cooled (condensed) to a cryogenic temperature. This may lower operation costs of the container <NUM>.

However, problems may occur when the liquified air begins to warm-up and evaporate. The boiling point of liquid air is between the boiling points of liquid nitrogen and liquid oxygen. As a result, as the liquid air boils and evaporates (because the mechanism to cool/condense the air has been switched-off, for example), the nitrogen component evaporates more rapidly than the oxygen component of the liquid air. This may result in a liquid air mixture that contains up to approximately <NUM>% concentration of oxygen. Liquid oxygen contains <NUM> times more oxygen by volume than normal air, and materials that are usually considered non-combustible (such as carbon, stainless steel, aluminium in powdered form, etc.) may burn in the presence of liquid oxygen. Accordingly, it may be desirable to reduce, minimise or eliminate the build-up of liquid oxygen within the container.

Thus, in embodiments, the at least one valve <NUM> may be coupled to an airflow mechanism for reducing or eliminating the build-up of liquid oxygen and frost within the container <NUM>. An example airflow mechanism is shown in <FIG>. The airflow mechanism may enable gas to flow into the sealed reservoir <NUM> of the container <NUM>, and may enable gas (e.g. evaporated - and therefore, warm - liquified gas) to flow out of the sealed reservoir <NUM>. The airflow mechanism may comprise a pipe <NUM> which is coupleable to valve <NUM>. Pipe <NUM> may be bifurcated or shaped into a first branch and a second branch, as shown in <FIG>. An inlet is provided on the first branch of pipe <NUM>, to enable gas (e.g. air from the external environment) to flow into the sealed reservoir <NUM> of container <NUM>. A one-way valve <NUM> is provided along the first branch, which may prevent evaporated air from within the sealed reservoir to flow along the first branch and impact the functionality of the inlet. An outlet is provided on the second branch of pipe <NUM>, to enable gas (including evaporated liquified gas) to flow out of the sealed reservoir <NUM>. A one-way valve <NUM> is provided along the second branch of pipe <NUM>, which may prevent gas from outside of the container <NUM> from flowing through the second branch and into the sealed reservoir.

In embodiments, to reduce build-up of liquid oxygen within the sealed reservoir <NUM>, the airflow mechanism may comprise a chamber <NUM> located between the inlet and the one-way valve <NUM> on the first branch of pipe <NUM>. The chamber <NUM> may contain an oxygen scavenger. An oxygen scavenger, or oxygen absorber, is a material that helps to remove or decrease the level of oxygen. The oxygen scavenger may be an iron-based oxygen scavenger, or may be a non-ferrous oxygen scavenger. Thus, oxygen from the gas (e.g. air) that flows into the inlet of pipe <NUM> may be at least partly removed, which reduces the potential build-up of liquid oxygen when the gas is condensed within the sealed reservoir <NUM>. In embodiments, chamber <NUM> may be removably provided on the first branch of pipe <NUM>. This may enable the entire chamber <NUM> to be removed to enable the oxygen scavenger to be disposed of and replaced with fresh oxygen scavenging material. In embodiments, the entire chamber <NUM> may be disposed of, and replaced with a new chamber <NUM> containing fresh oxygen scavenging material. Additionally or alternatively, the chamber <NUM> may be openable in situ to enable the oxygen scavenger to be removed and replaced with fresh material.

In embodiments, to reduce build-up of frost within the sealed reservoir <NUM> (which may reduce the cooling potential of the condensed gas), the airflow mechanism may comprise a chamber <NUM> located on the first branch of pipe <NUM>. If no chamber <NUM> is provided, the chamber <NUM> is located between the inlet and the one-way valve <NUM> on the first branch of pipe <NUM>. If chamber <NUM> is also present, chamber <NUM> is located between chamber <NUM> and the one-way valve <NUM> on the first branch of the pipe <NUM>, i.e. after the chamber containing the oxygen scavenging material. Chamber <NUM> contains a desiccant or other suitable material for absorbing moisture/water from the input gas. Removing moisture/water from the input air reduces the potential for frost or ice to form within the container <NUM>, and particularly in the sealed reservoir <NUM>. Frost or ice may reduce the efficiency of the cooling provided by the condensed gas, by inhibiting thermal energy transfer between the sealed reservoir <NUM> and the cavity <NUM>. The chamber <NUM> may be removably provided on the first branch of pipe <NUM>. This may enable the entire chamber <NUM> to be removed to enable the desiccant to be disposed of and replaced with fresh desiccant. In embodiments, the entire chamber <NUM> may be disposed of, and replaced with a new chamber <NUM> containing fresh desiccant. Additionally or alternatively, the chamber <NUM> may be openable in situ to enable the desiccant to be removed and replaced with fresh material.

In embodiments, a single valve <NUM> may be able to function as both a pressure relief valve and an inlet valve.

Thus, in embodiments, the at least one valve <NUM> is an inlet valve for filling the sealed reservoir with gas or liquified gas. The inlet valve may be coupleable to an airflow mechanism to enable gas to flow into the sealed reservoir (where it can be condensed to provide liquified gas), and to enable evaporated gas to flow out of the sealed reservoir. The airflow mechanism may comprise at least one chamber located between a gas inlet and the inlet valve. The at least one chamber may contain an oxygen scavenger or a desiccant. In embodiments, a flow sensor may be provided within the inlet valve to detect fluid flow in and/or out of the sealed reservoir, and in particular to detect the flow of evaporated liquified gas out of the reservoir.

The container <NUM> may comprise a heat engine <NUM> for condensing gas in the sealer reservoir <NUM> to provide liquified gas, and/or for cooling the liquified gas <NUM> in the sealed reservoir <NUM>. The heat engine may be a cryocooler, Kleemenco cycle cryocooler, pulse tube cryocooler, "acoustic Stirling" cryocooler, Joule Thompson cryocooler, Stirling cryocooler (also known as a Stirling engine), or any other suitable means of refrigeration. In embodiments, the heat engine may be a Stirling cryocooler having at least 20W cooling capacity at <NUM>. The heat engine <NUM> may be used to condense / re-liquify evaporated liquified gas within the sealed reservoir <NUM>, to maintain the level of/volume of cryogen within the container <NUM>.

The container <NUM> may comprise a heat exchanger <NUM> coupled to the heat engine <NUM>. The heat exchanger <NUM> may extend into the sealed reservoir <NUM> to provide cooling to the liquified gas <NUM>, as shown in <FIG>. Accordingly, the heat exchanger <NUM> may be able to extract heat from the top of the sealed reservoir <NUM>, in order to cool the liquified gas <NUM> and to condense any evaporated liquified gas <NUM> which may rise to the top of the sealed reservoir <NUM>. Arrows <NUM> show the direction of flow of condensate formed when the heat engine <NUM> and heat exchanger <NUM> are switched on.

When liquified gas in the sealed reservoir <NUM> evaporates, the evaporated liquified gas rises to the top of the sealed reservoir <NUM>, where it may be in proximity to the heat exchanger <NUM>, which is coupled to the heat engine <NUM>. The heat engine <NUM> may be operating at a temperature below the saturation temperature at the pressure of the liquified gas in the sealed reservoir <NUM> (e.g. <NUM> for liquefaction at <NUM> bar for liquid nitrogen), to achieve liquefaction/condensation of the evaporated liquified gas. When not being employed to liquefy a gas, the heat engine <NUM> may be used to reduce the temperature of the liquified gas within the sealed reservoir <NUM>, and thereby reduce evaporation.

As mentioned above, the container <NUM> may comprise at least one sensor <NUM> in the sealed reservoir <NUM> for sensing a volume or level of liquified gas <NUM> within the sealed reservoir <NUM>. It will be understood that the position of the sensor <NUM> in <FIG> is illustrative and non-limiting.

The container <NUM> may comprise at least one controller (not shown in <FIG>) coupled to the at least one sensor <NUM>. The controller <NUM> may be configured to: determine whether the at least one sensor <NUM> indicates that the volume of liquified gas <NUM> is below a required volume; and send a control signal to the heat engine <NUM> to switch on the heat engine, to thereby condense any evaporated liquified gas in the sealed reservoir <NUM>.

As mentioned above, the at least one valve <NUM> may be, or may comprise, a flow sensor, which may detect gas flow into and/or out of the sealed reservoir <NUM>. The flow sensor may be coupled to the controller, such that if the flow sensor indicates that gas is escaping from the sealed reservoir, the controller can take action to remedy the situation. For example, the controller may send a signal to heat engine <NUM> to switch-on to cool/condense the gas, and thereby reduce or stop the flow of gas out of the sealed reservoir <NUM>. The controller may send a signal to heat engine <NUM> to switch-off when the flow sensor indicates that the gas flow out of the sealed reservoir <NUM> has reduced significantly or stopped, as this may be indicative of the re-condensation of evaporated liquified gas in the sealed reservoir <NUM>. The flow sensor may enable the controller to provide a faster response than a level/volume sensor <NUM>.

In embodiments, the controller may be further configured to: determine whether, after a specified time, the at least one sensor <NUM> indicates that the volume of liquified gas <NUM> is below a required volume; send a control signal to the heat engine <NUM> to switch off the heat engine; and output a message, responsive to the determining, indicating that liquified gas needs to be added to the sealed reservoir <NUM>. The specified time may be a time after which it is expected that the required volume will be reached. This may be determined from experiments/calibration of the container <NUM>. In embodiments, the controller may be able to determine from the data from the at least one sensor <NUM> how much of a volume deficit there is within the sealed reservoir <NUM> (i.e. the difference between the required volume and the sensed volume), how long the heat engine <NUM> must be switched-on for in order to reach the required volume. This may determine the specified time after which the sensor(s) may be polled again.

In embodiments, container <NUM> may comprise a power meter (not shown in <FIG>) for measuring power consumption of the heat engine <NUM> when switched on/being used to cool the sealed reservoir <NUM>.

The above-mentioned controller, or a further controller, may be coupled to the power meter. The controller may be configured to: determine whether the measured power consumption of the heat engine <NUM> exceeds an expected power consumption; and output a report, responsive to the determining, on the integrity of the container <NUM> if the measured power consumption exceeds an expected power consumption. In this way, the integrity of the container <NUM> may be determined. For example, if the heat engine <NUM> is determined to be using more power than expected, then the container <NUM> may not be well-insulated or there may be a leak in the sealed reservoir which is causing liquified gas to evaporate or leak out of the container <NUM>.

The container <NUM> may comprise a communication module (not shown in <FIG>) for communicating information to any one or more of: a user of the container; a remote server; a manufacturer or supplier of the container; an electronic display; an electronic device. For example, the reports on the integrity of the container and/or the message regarding topping-up the reservoir with more liquified gas, may be communicated to a user or to a device/server external to the container <NUM> so that the relevant action can be taken.

The container <NUM> may comprise vacuum insulation/ a vacuum insulation layer <NUM>. The vacuum insulation <NUM> may be provided by one or more vacuum insulated panels. As shown in <FIG>, the vacuum insulation surrounds the sealed reservoir <NUM> and the cavity <NUM>, to prevent both the liquified gas in the sealed reservoir <NUM> and the samples <NUM> in the cavity <NUM> from heating-up. In contrast, the sealed reservoir <NUM> at least partly surrounds the cavity <NUM> such that the cold liquified gas is able to keep the cavity <NUM> and samples <NUM> at the required temperature.

The container <NUM> may comprise a removable insulated lid or cover <NUM>, wherein the housing and the cavity <NUM> are sealable by the removable lid <NUM>.

The container <NUM> described herein may be for storing cryopreserved biological samples and/or for shipping cryopreserved biological samples.

<FIG> is a flow diagram of example steps to monitor the volume of liquified gas within the container of <FIG>. At step S200, the at least one sensor <NUM> is used to sense/measure the volume of liquefied gas in the sealed reservoir <NUM>. A controller or processor (or similar component(s)) determine, using the sensor data, whether the sensed volume of liquified gas is below the required volume (step S202). The required volume is a volume needed to ensure the cavity <NUM> of the container <NUM>, and therefore the samples <NUM>, are at a required temperature for ensuring sample integrity. If the sensed volume is equal to or greater than the required volume, the process returns to step S200. If the sensed volume is below the required volume, the controller sends a control signal to switch on the heat engine <NUM>, to thereby condense any evaporated liquified gas in the sealed reservoir <NUM> and to reduce the temperature in the reservoir (step S204).

After a specified time T, the controller may send a control signal to switch off the heat engine <NUM> (step S206). Data from the at least one sensor <NUM> may be read again to determine the current volume of liquified gas in the sealed reservoir <NUM> (step S208). The specified time may be a time after which it is expected that the required volume will be reached. This may be determined from experiments/calibration of the container <NUM>. In embodiments, the controller may be able to determine from the data from the at least one sensor <NUM> how much of a volume deficit there is within the sealed reservoir <NUM> (i.e. the difference between the required volume and the sensed volume), how long the heat engine <NUM> must be switched-on for in order to reach the required volume. This may determine the specified time after which the sensor(s) may be polled again. (As mentioned above, the flow sensor in valve <NUM> may be used in addition to or instead of the level/volume sensor <NUM> to determine when the heat engine <NUM> may need to be switched-on to counteract evaporation of the liquified gas in the sealed reservoir <NUM>. The flow sensor may give a better and faster response than a level/volume sensor <NUM>).

At step S210, the controller determines whether the sensed volume is still below the required volume. If the sensed volume is at least equal to the required volume, the process returns to step S200. If the sensed volume is still below the required volume, the controller may be configured to output a message or control signal indicating that liquified gas needs to be added to the sealed reservoir <NUM> (i.e. that the sealed reservoir <NUM> needs to be topped-up with more liquified gas from an external source) (step S212). As mentioned above, this may be achieved by using the communication module to communicate with a user of the container or with external devices/servers. In embodiments, at step S212, the controller may cause a warning light or similar to be displayed or for an alarm to be sounded if liquified gas needs to be added to the container. After the reservoir has been topped-up (either with gas that is condensed to provided liquified gas, or with liquified gas) such that the required volume of liquified gas is achieved, the process returns to step S200.

<FIG> is a flow diagram of example steps to monitor fluid flow out of the container of <FIG>, and in particular the flow of evaporated liquified gas out of the sealed reservoir <NUM> of container <NUM>. At step S300, the flow sensor in valve <NUM> is used to detect/sense flow of evaporated liquified gas out of the sealed reservoir <NUM>. A controller or processor (or similar component(s)) instructs, responsive to the flow sensor data, the cryocooler/heat engine <NUM> to switch-on to cool the liquified gas in the sealed reservoir and condense any evaporated liquified gas in the sealed reservoir, to thereby stop or substantially reduce the flow of evaporated liquified gas out of the sealed reservoir <NUM> (step S302).

The controller continues to either receive data from the flow sensor, or to regularly poll the flow sensor, in order to determine if gas flow out of the sealed reservoir <NUM> has significantly reduced or stopped (step S304). If the flow sensor data indicates that gas flow out of the sealed reservoir <NUM> (through valve <NUM>) has significantly reduced or stopped, the controller instructs the heat engine <NUM> to switch-off (step S306), and the process returns to step S300. However, if the flow sensor data indicates that gas continues to flow out of the sealed reservoir <NUM> at an unacceptable rate, then the controller determines if a specified time T has lapsed since the heat engine <NUM> was switched-on (step S308). Time T may be a time which is determined from experiments/calibration of the container <NUM> and is the time it takes for condensation of evaporated liquified gas to be substantially completed. Alternatively, time T may be a maximum time for which the heat engine <NUM> may be run, for the purpose of power efficiency of the container, for example.

If at step S308, time T has not yet been reached, the controller allows the heat engine <NUM> to keep running (step S310). However, if at step S308, time T has been reached but gas is still flowing out of the sealed reservoir <NUM>, then the controller may first instruct the heat engine <NUM> to switch off (step S312) and then may be configured to output a message or control signal indicating that liquified gas needs to be added to the sealed reservoir <NUM> (i.e. that the sealed reservoir <NUM> needs to be topped-up with more liquified gas from an external source) (step S314). As mentioned above, this may be achieved by using the communication module to communicate with a user of the container or with external devices/servers. In embodiments, at step S314, the controller may cause a warning light or similar to be displayed or for an alarm to be sounded if liquified gas needs to be added to the container. After the reservoir has been topped-up (either with gas that is condensed to provided liquified gas, or with liquified gas) such that the required volume of liquified gas is achieved, the process returns to step S300.

In embodiments, the methods shown in <FIG> and <FIG> may be combined.

Thus, in embodiments, there is provided a method of monitoring the volume of liquified gas within the container, the method comprising: determining whether at least one sensor indicates that the volume of liquified gas is below a required volume and/or that evaporated liquified gas is flowing out of the sealed reservoir; and sending a control signal to switch on the heat engine, to condense any evaporated liquified gas in the sealed reservoir of the container.

The method may further comprise: determining whether, after a specified time, the at least one sensor indicates that the volume of liquified gas is still below a required volume; sending a control signal to switch off the heat engine; and outputting a message, responsive to the determining, indicating that liquified gas needs to be added to the sealed reservoir.

The method may further comprise: determining whether, after a specified time, the at least one sensor indicates that evaporated liquified gas is still flowing out of the sealed reservoir; sending a control signal to switch off the heat engine; and outputting a message, responsive to the determining, indicating that liquified gas needs to be added to the sealed reservoir.

<FIG> is a flow diagram of example steps to monitor the integrity of the container of <FIG>. As mentioned above, a controller may be coupled to a power meter, where the power meter measures power consumption of the heat engine <NUM> during operation. Thus, as step S400, the process involves measuring the power input into, or power consumed by, the heat engine <NUM>. The controller may be configured to determine whether the measured power consumption of the heat engine <NUM> exceeds an expected power consumption (step S402). If the measured power consumption is equal to or below an expected power consumption, then the process may return to step S400. If the measured power consumption exceeds an expected power consumption, then the controller may output a report on the integrity of the container <NUM> (step S404). In this way, the integrity of the container <NUM> may be determined. For example, if the heat engine <NUM> is determined to be using more power than expected, then the container <NUM> may not be well-insulated or there may be a leak in the sealed reservoir which is causing liquified gas to evaporate or leak out of the container <NUM>.

Thus, in embodiments, there is provided a method of monitoring integrity of the container, the method comprising: determining whether a measured power consumption of the heat engine of the container exceeds an expected power consumption; and outputting a report, responsive to the determining, on the integrity of the container if the measured power consumption exceeds an expected power consumption.

Embodiments of the present techniques also provide a non-transitory data carrier carrying code which, when implemented on a processor, causes the processor to carry out the methods described herein.

The techniques further provide processor control code to implement the above-described methods, for example on a general purpose computer system or on a digital signal processor (DSP). The techniques also provide a carrier carrying processor control code to, when running, implement any of the above methods, in particular on a non-transitory data carrier or on a non-transitory computer-readable medium such as a disk, microprocessor, CD- or DVD-ROM, programmed memory such as read-only memory (firmware), or on a data carrier such as an optical or electrical signal carrier. The code may be provided on a (non-transitory) carrier such as a disk, a microprocessor, CD- or DVD-ROM, programmed memory such as non-volatile memory (e.g. Flash) or read-only memory (firmware). Code (and/or data) to implement embodiments of the techniques may comprise source, object or executable code in a conventional programming language (interpreted or compiled) such as C, or assembly code, code for setting up or controlling an ASIC (Application Specific Integrated Circuit) or FPGA (Field Programmable Gate Array), or code for a hardware description language such as Verilog™ or VHDL (Very high speed integrated circuit Hardware Description Language). As the skilled person will appreciate, such code and/or data may be distributed between a plurality of coupled components in communication with one another. The techniques may comprise a controller which includes a microprocessor, working memory and program memory coupled to one or more of the components of the system.

Computer program code for carrying out operations for the above-described techniques may be written in any combination of one or more programming languages, including object oriented programming languages and conventional procedural programming languages. Code components may be embodied as procedures, methods or the like, and may comprise sub-components which may take the form of instructions or sequences of instructions at any of the levels of abstraction, from the direct machine instructions of a native instruction set to high-level compiled or interpreted language constructs.

It will also be clear to one of skill in the art that all or part of a logical method according to the preferred embodiments of the present techniques may suitably be embodied in a logic apparatus comprising logic elements to perform the steps of the above-described methods, and that such logic elements may comprise components such as logic gates in, for example a programmable logic array or application-specific integrated circuit.

In an embodiment, the present techniques may be realised in the form of a data carrier having functional data thereon, said functional data comprising functional computer data structures to, when loaded into a computer system or network and operated upon thereby, enable said computer system to perform all the steps of the above-described method.

Claim 1:
A container (<NUM>) for cryopreserved biological samples, the container (<NUM>) comprising:
an insulated housing comprising a cavity (<NUM>) for containing at least one cryopreserved biological sample (<NUM>); and
a sealed reservoir (<NUM>) at least partly surrounding the cavity (<NUM>) of the housing, the sealed reservoir (<NUM>) comprising liquified gas (<NUM>), the sealed reservoir (<NUM>) further comprising an inlet valve (<NUM>) for filling the sealed reservoir (<NUM>) with gas or liquified gas,
the container (<NUM>) further comprising a heat transfer engine (<NUM>) for condensing gas in the sealed reservoir (<NUM>) to provide liquified gas, or cooling the liquified gas (<NUM>) in the sealed reservoir (<NUM>); and
an airflow mechanism, wherein the valve (<NUM>) is couplable to the airflow mechanism to enable gas to flow into the sealed reservoir (<NUM>) and to enable evaporated gas to flow out of the sealed reservoir (<NUM>) and wherein the airflow mechanism comprises a chamber (<NUM>) containing an oxygen scavenger and/or a chamber (<NUM>) containing a desiccant, the chamber(s) (<NUM>, <NUM>) being located between a gas inlet and the inlet valve (<NUM>).