CN112361705B

CN112361705B - A biological sample freezing rack capable of zoned temperature control and a program temperature control device

Info

Publication number: CN112361705B
Application number: CN202011144819.7A
Authority: CN
Inventors: 赵嘉峰; 魏才怿; 谢斌平
Original assignee: Fermi Instruments Shanghai Co ltd; Feimian Instrument Technology Nanjing Co ltd
Current assignee: Fermi Instruments Shanghai Co ltd; Feimian Instrument Technology Nanjing Co ltd
Priority date: 2020-10-23
Filing date: 2020-10-23
Publication date: 2025-02-07
Anticipated expiration: 2040-10-23
Also published as: CN112361705A

Abstract

The invention provides a biological sample freezing frame capable of controlling temperature in a partitioned manner and program temperature control equipment, which are characterized by comprising a heat sink cold plate, a cooling unit and a control module, wherein the upper surface of the heat sink cold plate is connected with a plurality of independent cooling units, the control module is connected with and controls the cooling units, the lower surface of the heat sink cold plate is connected with a refrigeration source, and the cooling units comprise sample grooves, heating elements, temperature sensors and heat insulation covers. The device has the beneficial effects that by designing the independent cooling unit and the heat sink, the device can independently operate samples collected at different times in batches in multiple channels, and the control module receives the data of the temperature sensor of the independent cooling unit, so that the working power of the heating element is regulated, the frozen samples are cooled at the optimal cooling rate, and the optimal freezing effect is achieved.

Description

Biological sample cryopreserving frame capable of controlling temperature in partitioned mode and program temperature control equipment

Technical Field

The invention relates to the field of biological low-temperature storage, in particular to a biological sample freezing and storing frame capable of controlling temperature in a partitioning way and program temperature control equipment.

Background

In performing preservation of cells or biological samples, freezing the sample to ultra-low temperatures (below-80 degrees celsius) using suitable methods and maintaining the temperature for a long period of time is a key element of biological freezing technology. A common preservation method is to suspend the sample in a solution with cryoprotectant and store it for a long period of time after cooling to ultra low temperature at a certain freezing rate. The mode capable of meeting the requirement of precisely controlling the cooling rate is to adopt a program cooling instrument, and the temperature is reduced according to a preset curve by software aiming at a specific biological sample.

The existing mainstream technology adopts a liquid nitrogen refrigeration type program cooling instrument, and the sample freezing cabin is cooled according to a preset cooling curve by controlling the liquid nitrogen injection flow. More importantly, the liquid nitrogen consumption is high due to the long time for single operation, and the batch operation of collecting a certain number of biological samples is more used. In the use environment of a hospital or a scientific laboratory, a small amount of precious samples, such as various experimental cell samples, oocytes, patient stem cells and the like, need to be frozen at a controlled rate as soon as possible while being collected, so as to obtain higher activity when being thawed, and then the next experiment/treatment can be ensured to be effective. Therefore, in order to meet the demand of rapidly developed biomedicine for cryopreserving biological samples, in order to accurately control the cooling process of the samples and realize taking along with storage, the invention provides a biological sample cryopreservation rack capable of controlling temperature in a partitioning way and program cooling equipment.

Disclosure of Invention

In order to solve the technical problems, the invention discloses a biological sample freezing and storing rack capable of controlling temperature in a partitioning way and program temperature control equipment, and the technical scheme of the invention is implemented as follows:

The biological sample freezing and storing frame capable of controlling temperature in a partitioned mode comprises a heat sink cold plate, a cooling unit and a control module, wherein the upper surface of the heat sink cold plate is connected with a plurality of independent cooling units, the control module is connected with and controls the cooling units, each cooling unit comprises a sample groove, a heating element, a temperature sensor and a heat insulation cover, the heating element and the temperature sensor are located on the side wall of the sample groove, and the heat insulation cover is located on the upper portion of the sample groove.

Preferably, the heat sink cold plate comprises a reference hole, the upper surface of the heat sink cold plate is provided with a concave-convex structure, the cooling unit comprises a sample support and a connecting column, the connecting column is positioned at the bottom of the sample support, the connecting column is matched and fixed with the reference hole, a multi-circuit channel is arranged in the heat sink cold plate, and the upper surface of the heat sink cold plate is covered with a heat insulating material.

Preferably, the aperture size of the sample groove is 1-100mm, the depth of the sample groove is 1-200mm, and the number of sample holes in the sample groove is 1 or more.

Preferably, the cooling unit further comprises a thermal connecting piece, and the cooling unit is fixedly connected with the heat sink cold plate through the thermal connecting piece.

Preferably, the thermal connector is made of sapphire, and the thickness of the thermal connector is 0.1-20mm.

Preferably, the thermal connector comprises a micro-expansion low temperature thermal switch.

A program cooling device comprises a biological sample freezing frame capable of controlling temperature in a partitioning mode, a sample freezing frame shell and a refrigerating unit, wherein the refrigerating unit comprises a refrigerating source, the refrigerating source is located in the refrigerating unit, and the refrigerating source is in contact with the lower surface of a heat sink cold plate.

Preferably, the refrigerating source is a refrigerator, and the refrigerator comprises a cold head which is connected with the lower surface of the heat sink cold plate.

Preferably, the refrigeration source is a refrigerant, the refrigeration unit comprises a Dewar vessel, the refrigerant is loaded in the Dewar vessel, and an opening of the Dewar vessel is coupled with the lower surface of the heat sink cold plate.

By means of the technical scheme, the technical effects that multiple groups of samples can be operated in batches on the premise that the samples are not removed, the sample freezing frame is in butt joint with various refrigeration equipment, the program cooling function can be achieved, and the technical effect of the biological sample short-term low-temperature storage function is achieved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are only one embodiment of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.

Wherein like parts are designated by like reference numerals. It should be noted that the words "front", "back", "left", "right", "upper" and "lower" used in the following description refer to directions in the drawings, and the words "bottom" and "top", "inner" and "outer" refer to directions toward or away from, respectively, the geometric center of a particular component.

FIG. 1 is a schematic block diagram of a biological sample cryopreservation frame capable of controlling temperature in a partitioning manner;

FIG. 2 is a schematic structural view of a biological sample freezing rack capable of controlling temperature in a partitioning manner;

fig. 3 is a schematic structural view of embodiment 2;

FIG. 4 is a schematic diagram of a connection structure of a thermal connector and a heatsink cold plate;

Fig. 5 is a schematic structural diagram of embodiment 4.

In the above drawings, each reference numeral indicates:

1 heat sink cold plate

1-1, Reference hole

2, Cooling unit

2-1, Sample tank

2-2 Heating element

2-3, Temperature sensor

2-4, Heat insulation cover

2-5, Sample holder

2-6, Connecting column

3, Control module

4, Thermal connector

5, Sample cryopreservation frame shell

6, Cooling unit

6-1, Cold header

6-2, Du Waqi dishes

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

Example 1

In a specific embodiment 1, as shown in fig. 1 and 2, a biological sample freezing and storing rack capable of controlling temperature in a partitioning manner comprises a heat sink cold plate 1, a cooling unit 2 and a control module 3, wherein the upper surface of the heat sink cold plate 1 is connected with a plurality of independent cooling units 2, the control module 3 is connected with and controls the cooling units 2, the cooling units 2 comprise a sample groove 2-1, a heating element 2-2, a temperature sensor 2-3 and a heat insulation cover 2-4, the heating element 2-2 and the temperature sensor 2-3 are positioned on the side wall of the sample groove 2-1, and the heat insulation cover 2-4 is positioned on the upper part of the sample groove 2-1.

In this embodiment, the heat sink cooling plate 1 is made of a metal material with high heat conductivity, such as aluminum, copper, alloy, etc., and the upper end of the heat sink cooling plate 1 is provided with a plurality of independent cooling units 2, and each cooling unit 2 comprises a sample tank 2-1, a heating element 2-2, a temperature sensor 2-3, and a heat insulation cover 2-4. The single sample tank 2-1 is made of metal materials with high heat conductivity, such as aluminum, copper, alloy and the like, and can be used for loading the sample tube, and the heat insulation cover 2-4 at the upper part of the sample tank 2-1 can cover the exposed part of the sample tube to isolate the sample tube from the influence of the heat energy change of the surrounding environment. The side wall of the single sample tank 2-1 is fixedly provided with a heating element 2-2 and a temperature sensor 2-3, the temperature sensor 2-3 collects the temperature of the sample tank 2-1 (namely, represents the current sample temperature) and feeds the temperature back to the control module 3, and the control module 3 controls the power of the heating element 2-2 according to the fed-back temperature. The control module 3 may be a single chip microcomputer including a processor, a POC, a PC system, etc. The temperature sensor 2-3 may be a thermocouple thermometer and a thermal resistance thermometer of various types, the heating element 2-2 may be a heater of various types such as a ceramic heater, a semiconductor heater, a thin film heater, etc., the power of the heating element 2-2 may be 1W to 200W, and in use, the lower surface of the heat sink cold plate 1 may be in direct contact with a refrigeration source, which may be liquid nitrogen, liquid helium, liquid hydrogen, liquid fluorine, liquid oxygen, liquid methane, and various stirling refrigerators, GM refrigerators, J-T refrigerators, pulse tube refrigerators, etc. Because the cooling capacity provided by the refrigeration source is sufficient, the temperature of the heat sink cold plate 1 is not influenced by the change of the heat energy of the upper end cooling units 2, and the heating elements 2-2 and the temperature sensors 2-3 of the plurality of cooling units 2 are independent of each other, so that the operation such as program cooling, freezing preservation and rapid re-warming can be independently performed on the single cooling unit 2, the time-sharing partition cooling, storage and re-warming of the plurality of cooling units 2 are realized, and the temperature can be simultaneously reduced at different optimal rates according to biological samples with different characteristics, so that the optimal freezing preservation effect is achieved.

Taking two samples A and B to be frozen as an example, in actual use, after the heat sink cold plate 1 is abutted against a refrigeration source such as a refrigerant or a refrigerator, the temperature of the heat sink cold plate 1 will be rapidly reduced to ultralow temperature, and meanwhile, the heat sink cold plate 1 will be continuously in a low temperature state, and at the moment, the temperature of the cooling units 2A and 2B of the heating elements 2-2A and 2-2B is also reduced to ultralow temperature. Since the initial temperatures of the samples A and B to be frozen are generally close to the room temperature or the cold storage temperature, the heating elements 2-2A, 2-2B need to be activated to maintain the initial temperatures of the sample tanks 2-1A, 2-1B at 4℃to 20℃before the samples are put into the sample tanks 2-1A, 2-1B for controlled cooling. After the temperatures of the sample tanks 2-1A and 2-1B reach the initial set values, the sample A can be put in, the cooling rate vA (v, t) of the sample tank 2-1A is preset through the control module 3, and the program cooling process is started. The sample B can be placed at any time, the cooling rate vB (v, t) of the sample tank 2-1B is preset by the control module 3, and the program cooling process is started. In the process of program cooling, the temperature sensors 2-3A, B respectively read the temperature of the current sample tank 2-1A, B and feed back the temperature to the control module 3, and the control module 3 adjusts the power of the heating elements 2-2A and 2-2B according to the temperature, so that the temperatures of the sample tanks 2-1A and 2-1B respectively change according to a preset cooling curve, and the purpose of accurate cooling is achieved. After the temperature of the sample cell 2-1A, 2-1B has fallen to the set point, the control module 3 will maintain the heating element 2-2A, 2-2B operating at the current power level and continuously monitor the temperature of the sample cell 2-1A, 2-1B to maintain it stable. If necessary, the control module 3 can also control the heating elements 2-2A and 2-2B to heat the sample tanks 2-1A and 2-1B in a low temperature state so as to quickly rewet the frozen sample.

The embodiment is provided with a plurality of independent cooling areas, multiple groups of samples can be operated in batches on the premise of not moving out the samples, the waiting time from the collection to the freezing of the samples is shortened along with the storage and the taking, the sample recovery effect is improved, and the samples can be cooled at different optimal cooling rates to achieve the optimal freezing preservation effect. The program cooling equipment adopting the refrigerator as the refrigeration source has a small structure, and the configuration of the mobile power supply is applicable to the long-distance transportation of biological samples, the collection of wild and multi-place biological samples and other use scenes. The method adopts the refrigerant as the program cooling equipment of the refrigeration source, has less refrigerant consumption and high refrigeration efficiency, can realize batch operation of a large number of samples, and is suitable for large-scale GMP cell production centers and the storage requirement of a biological sample library on a large number of biological samples.

Example 2

In a preferred embodiment 2, as shown in fig. 1,2 and 3, a heat sink cold plate 1 includes a reference hole 1-1, an uneven structure is provided on an upper surface of the heat sink cold plate 1, a cooling unit 2 includes a sample holder 2-5 and a connection column 2-6, the connection column 2-6 is located at a bottom of the sample holder 2-5, the connection column 2-6 is matched and fixed with the reference hole 1-1, a multi-circuit channel is provided inside the heat sink cold plate 1, and an insulating material is covered on the upper surface of the heat sink cold plate 1.

In this embodiment, the upper surface of the heat sink cooling plate 1 is designed into a concave-convex structure, the cooling unit 2 is fixed on the concave-convex structure corresponding to the heat sink cooling plate 1 in a pluggable manner through the sample support 2-5, the sample support 2-5 can be a multi-pin pluggable sample support commonly used for sample measurement at low temperature, the bottom of the sample support 2-5 is provided with a connecting column 2-6, such as 10pin or 12pin, and the like, a reference hole 1-1 is arranged in a protruding part of the heat sink cooling plate 1, and the aperture can just accommodate the connecting column 2-6. The cooling unit 2 is fixed on the sample support 2-5, the control circuit of the heating element 2-2 and the temperature sensor 2-3 in the cooling unit 2 is connected with the reference hole 1-1 on the heat sink cold plate 1 through the connecting column 2-6 of the sample support 2-5, and then is connected to the control module 3 through the multi-channel circuit inside the heat sink cold plate 1, so that excessive exposure of wires can be avoided, the cooling unit 2 is convenient to plug and pull, maintenance and replacement are convenient, and the main body of the sample support 2-5 can be made of metal materials with good heat conductivity. Meanwhile, the surface of the heat sink cold plate 1 is covered with heat insulation materials, so that the groove gaps and the gaps of the plurality of cooling units 2 are filled with the heat insulation materials, the heat insulation materials and the heat insulation covers 2-4 are used for preventing the cooling units 2 from being influenced by heat radiation of the surrounding environment, and meanwhile, the single independent cooling unit 2 only conducts heat in contact with the heat sink cold plate 1.

In a preferred embodiment, the sample cell 2-1 has a pore size of 1 to 100mm, the sample cell 2-1 has a depth of 1 to 200mm, and the number of sample pores in the sample cell 2-1 is 1 or more.

Because the sample tank 2-1 is used for loading the sample tube, in the actual biological low-temperature preservation, the sample tube has different specifications, such as a freezing tube, a straw, a vaccine, a medicine, a blood bag and the like, the size and the depth of the inner aperture of the sample tank 2-1 are matched with the sample tubes with different specifications, the depth of the sample tank 2-1 is such that part of the tube body and the tube cap of the sample tube are exposed, the sample tank 2-1 is convenient to access and operate, and a single sample tank 2-1 can accommodate at least one frozen sample, can also be designed to be matched with the specifications of various porous plates and SBS standard porous plates, accommodates a plurality of samples, and is convenient to be used in combination with a cell production line. When the sample tube to be treated is a straw, the upper surface of the sample tank 2-1 is designed as a transverse groove to accommodate the straw in an elongated shape, and when the sample to be treated is a blood bag, the upper surface of the sample tank 2-1 is designed as a plane.

Example 3

In a preferred embodiment 3, as shown in fig. 1, 2 and 4, the cooling unit 2 further includes a thermal connector 4, and is connected and fixed to the heat sink cold plate 1 through the thermal connector 4.

In the case where the amount of refrigeration provided by the refrigerant and refrigerator is very large and the temperature of the heat sink cold plate 1 is very low (e.g., less than-120C), if the sample cell 2-1 is in direct contact with the heat sink cold plate 1, the power of the heating element 2-2 may not be sufficient to maintain the initial temperature of the sample cell stable within the temperature interval of 4C to 20C. Therefore, by adopting the thermal connector 4, when the heating element 2-2 is started to raise the temperature of the sample tank 2-1, the thermal connector 4 is influenced by the temperature change of the sample tank 2-1, and the temperature of the thermal connector 4 is raised and the thermal conductivity is reduced, so that the heat transfer from the sample tank 2-1 to the heat sink cold plate 1 is reduced, the temperature of the sample tank 2-1 is further raised, and the initial temperature of the sample tank can be kept stable within a temperature range of 4-20 ℃ when the heating element 2-2 works at lower power. After the cooling procedure is started, the heat conductivity of the thermal connector 4 is increased along with the reduction of the temperature of the sample tank 2-1, so that the heat is promoted to be transmitted from the sample tank 2-1 to the heat sink cold plate 1, the adjustable cooling rate range is larger, and the cooling requirement of more biological samples can be met.

In a preferred embodiment, the thermal connector 4 is made of sapphire, and the thickness of the thermal connector 4 is 0.1-20mm.

Since, for example, sapphire increases in thermal conductivity with decreasing temperature in a temperature range of 30K or more, decreases with increasing temperature, weak thermal conductivity at high temperature and good thermal conductivity at low temperature can be exhibited. The heating element 2-2 can be used for effectively meeting the requirement of controlling the temperature rise and the temperature drop of the sample tank 2-1.

In a preferred embodiment, the thermal connector 4 comprises a micro-expansion low temperature thermal switch.

In this embodiment, the thermal connector 4 directly adopts a micro-expansion low-temperature thermal switch, and uses the difference of expansion and contraction rates of two different materials to realize the effect that the thermal connector 4 is opened at high temperature and closed at low temperature for conducting heat, so that the requirement of controlling the temperature rise and the temperature drop of the sample tank 2-1 by using the heating element 2-2 can be met.

Example 4

In a specific embodiment 4, as shown in fig. 1, 2 and 5, a program cooling device includes a biological sample freezing rack capable of controlling temperature in a partitioning manner, a sample freezing rack housing 5 and a refrigeration unit 6 according to any embodiment of the present disclosure, wherein the refrigeration unit 6 includes a refrigeration source, the refrigeration source is located in the refrigeration unit 6, and the refrigeration source is in contact with the lower surface of the heat sink cold plate 1.

In this embodiment, a program cooling device of a biological sample freezing rack capable of controlling temperature in a partitioning manner is disclosed, in order to isolate the influence of external environment heat, the sample freezing rack housing 5 can be designed as a double-layer vacuum dewar bottle, a vacuum insulation panel, a polyurethane foaming composite material and other heat insulation devices, and the refrigeration source of the refrigeration unit 6 can adopt various types of refrigeration devices or refrigerants, such as liquid nitrogen, liquid helium, liquid hydrogen, liquid fluorine, liquid oxygen, liquid methane, various Stirling refrigerators, GM refrigerators, J-T refrigerators, pulse tube refrigerators and the like.

In a preferred embodiment, the refrigeration source is a refrigerator, and the refrigerator comprises a cold head 6-1, wherein the cold head 6-1 is connected with the lower surface of the heat sink cold plate 1.

When the refrigerating source adopts a refrigerator, the cold head 6-1 of the refrigerator is in direct contact with the lower surface of the heat sink cold plate 1, and the heat of the sample freezing and storing frame is removed in a contact type heat conduction mode. A damping device is arranged between the refrigerator and the sample freezing and storing frame so as to reduce potential damage to biological samples caused by vibration. The program cooling equipment adopting the single refrigerator has a small structure, and the configuration mobile power supply is applicable to long-distance transportation of biological samples, collection of wild and multi-place biological samples and use scenes of taking along with storage.

In a preferred embodiment, the refrigeration source is a refrigerant, the refrigeration unit 6 comprises Du Waqi dishes 6-2, the refrigerant is loaded in Du Waqi dishes 6-2, and the opening of Du Waqi dishes 6-2 is coupled with the lower surface of the heat sink cold plate 1.

When the refrigeration source of the refrigeration unit 6 adopts various types of refrigerants, the refrigerants can be loaded in the Du Waqi dish 6-2, the opening of the Du Waqi dish 6-2 is coupled with the heat sink cold plate 1, and the heat of the sample freezing frame is removed in a contact type heat conduction mode.

In the present invention:

The sample freezing frame can independently cool samples collected at different times in batches in multiple channels, shortens waiting time of samples from collection to freezing, improves sample recovery effect, and can cool a plurality of samples at different optimal cooling rates to achieve optimal freezing preservation effect.

The sample freezing frame is coupled with the refrigerant refrigeration source, so that the program cooling process can be realized with lower refrigerant consumption.

The sample freezing frame is coupled with a refrigerating mechanism refrigerating source to realize liquid nitrogen-free refrigeration, so that the biological sample is prevented from being polluted by liquid nitrogen, and the operation is safe and consumable-free.

The cooling units 2 of the sample freezing and storing rack are mutually independent, samples which are cooled do not need to be taken out in a short time, are not influenced by cooling operation of other samples, and can have a short-term low-temperature storage function.

The independent cooling unit 2 can be used for designing corresponding aperture sizes for the freezing storage pipes with different specifications and can be detached and replaced. The independent cooling unit 2 can be designed to be matched with various porous plates and SBS standard porous plate specifications, and is convenient to be used in combination with intelligent robot technology and high-throughput screening.

The temperature of each cooling unit 2 is regulated by the heating element 2-2 and the temperature sensor 2-3, and besides the cooling is controlled, the rapid re-heating of the sample can be controlled.

The temperature can be regulated and controlled to be +/-0.1 ℃.

It should be noted that the above-mentioned embodiments are only preferred embodiments of the present invention, and are not intended to limit the present invention, and any modifications, equivalent substitutions, improvements, etc. within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The biological sample freezing and storing frame capable of controlling temperature in a partitioned mode is characterized by comprising a heat sink cold plate, a cooling unit and a control module, wherein the heat sink cold plate is used for being in butt joint with a refrigeration source, the upper surface of the heat sink cold plate is connected with a plurality of independent cooling units, the control module is connected with and controls the cooling units, each cooling unit comprises a sample groove, a heating element, a temperature sensor and a heat insulation cover, the heating element and the temperature sensor are located on the side wall of the sample groove, and the heat insulation cover is located on the upper portion of the sample groove.

2. The biological sample cryopreserving frame capable of controlling temperature in a partitioning manner according to claim 1, wherein the heat sink cold plate comprises a reference hole, a concave-convex structure is arranged on the upper surface of the heat sink cold plate, the cooling unit comprises a sample support and a connecting column, the connecting column is positioned at the bottom of the sample support, the connecting column is matched and fixed with the reference hole, a multi-circuit channel is arranged in the heat sink cold plate, and the upper surface of the heat sink cold plate is covered with a heat insulation material.

3. The biological sample freezing and storing rack capable of controlling temperature in a partitioning manner according to claim 1, wherein the aperture of the sample groove is 1-100mm, the depth of the sample groove is 1-200mm, and the number of sample holes in the sample groove is 1 or more.

4. The biological sample cryopreservation frame capable of controlling temperature in a partitioning manner according to claim 1, further comprising a thermal connecting piece, wherein the cooling unit is fixedly connected with the heat sink cold plate through the thermal connecting piece.

5. The biological sample cryopreservation frame capable of controlling temperature in a partitioning manner according to claim 4, wherein the thermal connecting piece is made of sapphire, and the thickness of the thermal connecting piece is 0.1-20mm.

6. The biological sample cryopreservation frame capable of controlling temperature in a partitioning manner according to claim 4, wherein the thermal connector comprises a micro-expansion type low-temperature thermal switch.

7. A program cooling device is characterized by comprising a biological sample freezing frame capable of controlling temperature in a partitioning manner, a sample freezing frame shell and a refrigerating unit, wherein the refrigerating unit comprises a refrigerating source, and the refrigerating source is positioned in the refrigerating unit.

8. The program cooling device of claim 7, wherein the cooling source is a refrigerator, and the refrigerator comprises a cold head connected to the lower surface of the heat sink cold plate.

9. A program cooling device as set forth in claim 7 wherein the source of refrigerant is a refrigerant and the refrigeration unit comprises a Dewar vessel in which the refrigerant is loaded, the opening of the Dewar vessel being coupled to the lower surface of the heatsink cold plate.