A liquid nitrogen gradient cooling instrument

Abstract

The application provides a liquid nitrogen gradient cooling instrument, and relates to the technical field of cell freezing. The liquid nitrogen gradient cooling instrument comprises a tank body and a liquid nitrogen conveying assembly in communication with the bottom of the tank body. The liquid nitrogen conveying assembly comprises a liquid nitrogen tank and a pipeline in communication with the liquid nitrogen tank and the tank body. A control switch is arranged on the pipeline. A bearing table and a linear driver for driving the bearing table to move vertically are arranged in the tank body. A pressure sensor is also arranged in the tank body. The liquid nitrogen gradient cooling instrument further comprises a controller arranged on the tank body. The controller is electrically connected with the linear driver, the control switch, the pressure sensor and a temperature measuring element respectively. The controller is used for controlling the operation of the linear driver according to a temperature signal and controlling the opening and closing of the control switch according to a pressure signal of the pressure sensor. The liquid nitrogen gradient cooling instrument can improve the cold survival of cells and increase the success rate of recovery of frozen human umbilical cord blood hematopoietic stem cells.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cell freezing, in particular to a liquid nitrogen gradient cooling instrument. BACKGROUND

[0002] Human umbilical cord blood is the blood in the umbilical cord and the blood vessels near the fetus side of the placenta at the time of birth of a newborn, which contains human umbilical cord blood stem cells. The human umbilical cord blood stem cells are often used for transplantation treatment of various blood system diseases and immune system diseases, including blood system malignancies, bone marrow hematopoietic failure, congenital metabolic diseases, congenital immunodeficiency, autoimmune diseases, certain solid tumors, respiratory diseases, cardiovascular diseases, endocrine diseases, digestive diseases, etc. Therefore, the umbilical cord blood has become an important source of hematopoietic stem cells. The quantity of human umbilical cord blood hematopoietic stem cells is a direct influencing factor of the transplantation efficiency. Since the human umbilical cord blood hematopoietic stem cells cannot be massively expanded in vitro like other stem cells (such as mesenchymal stem cells), the human umbilical cord blood hematopoietic stem cells are particularly valuable. The umbilical cord blood hematopoietic stem cells are generally collected and processed, then sent to an umbilical cord blood bank for cryopreservation and waiting for reuse. The quantity of the umbilical cord blood hematopoietic stem cells after cryopreservation and recovery can directly affect the clinical transplantation efficiency in the later stage, so the cryopreservation and recovery process of the umbilical cord blood hematopoietic stem cells has higher requirements than other types of stem cells.

[0003] In the prior art, hematopoietic stem cells are directly cryopreserved in liquid nitrogen at-196℃. During the process of reducing the hematopoietic stem cells from normal temperature to-196℃, if the temperature is not reduced at a certain rate at different time points, the activity of the hematopoietic stem cells will be seriously reduced, and even the cells will die. Even if such hematopoietic stem cells are cryopreserved, the quantity of living cells after recovery will be greatly reduced, and the proliferation and differentiation ability will also be reduced. SUMMARY

[0004] The present application provides a liquid nitrogen gradient cooling instrument, which aims to solve the problems of cell death caused by sudden temperature drop, short cell preservation time, and low success rate of recovery of cryopreserved human umbilical cord blood hematopoietic stem cells in the prior art, and improve the cold survival of cells.

[0005] The embodiments of the present application are implemented as follows:

[0006] In one aspect of the embodiment of the present application, a liquid nitrogen gradient cooling instrument is provided, which comprises a tank body and a liquid nitrogen delivery assembly in communication with the bottom of the tank body. The liquid nitrogen delivery assembly comprises a liquid nitrogen tank and a pipeline in communication with the tank body. A control switch is arranged on the pipeline. A bearing table and a linear actuator for driving the bearing table to move vertically are arranged in the tank body. A pressure sensor is also arranged in the tank body. The liquid nitrogen gradient cooling instrument further comprises a controller arranged on the tank body and electrically connected with the linear actuator, the control switch, the pressure sensor and a temperature measuring element, for controlling the operation of the linear actuator according to the temperature signal and controlling the opening and closing of the control switch according to the pressure signal of the pressure sensor.

[0007] Optionally, the pressure sensor is arranged at the bottom of the tank body, and the pressure value detected by the pressure sensor is positively correlated with the volume of the liquid nitrogen in the tank body.

[0008] Optionally, the pipeline of the liquid nitrogen delivery assembly is in communication with the tank body at the bottom of the tank body.

[0009] Optionally, a lifting shaft is vertically arranged at the center of the tank body, and the bearing table is horizontally arranged on the lifting shaft and moves on the lifting shaft through the linear actuator.

[0010] Optionally, the liquid nitrogen gradient cooling instrument further comprises a conveyor belt connecting the linear actuator and the bearing table, and the linear actuator drives the bearing table to lift through the conveyor belt.

[0011] Optionally, a liquid discharge port is arranged at the bottom of the tank body, and an emergency liquid discharge valve is connected to the liquid discharge port.

[0012] Optionally, a heat preservation layer is arranged on the inner wall of the tank body.

[0013] Optionally, a support seat is arranged at the bottom of the tank body.

[0014] Optionally, an opening is arranged at the top of the tank body, and a cover is rotatably arranged on the tank body and can be covered on the opening.

[0015] Optionally, a display panel is further arranged on the tank body and electrically connected with the controller.

[0016] The beneficial effects of the embodiments of the present application include: the liquid nitrogen gradient cooling instrument provided by the embodiments of the present application comprises a tank body and a liquid nitrogen conveying assembly in communication with the bottom of the tank body, the liquid nitrogen conveying assembly comprises a liquid nitrogen tank and a pipeline in communication with the liquid nitrogen tank and the tank body, and a control switch is arranged on the pipeline, so that the liquid nitrogen is more convenient to control to enter or discharge the tank body; a bearing table and a linear driver for driving the bearing table to move in the vertical direction are arranged in the tank body, the bearing table is arranged to be more convenient to place the to-be-preserved piece, and the linear driver is arranged to effectively control the movement of the bearing table in the vertical direction, so that the to-be-preserved piece can smoothly reach the preset temperature within the preset time; a pressure sensor is further arranged in the tank body, and the pressure value detected by the pressure sensor is convenient to know the volume of the liquid nitrogen in the tank body; the liquid nitrogen gradient cooling instrument further comprises a controller arranged on the tank body, the controller is electrically connected with the linear driver, the control switch, the pressure sensor and a temperature measuring element respectively, and is used for controlling the operation of the linear driver according to the temperature signal and controlling the opening and closing of the control switch according to the pressure signal of the pressure sensor. When the liquid nitrogen gradient cooling instrument is actually operated, the operator can first preset the temperature and time through the device, can directly observe the real-time temperature of the environment in which the to-be-preserved piece is located, can transmit the temperature signal to the controller, can control the linear driver to drive the bearing table to move in the vertical direction according to the preset temperature, and can further control the to-be-preserved piece to smoothly reach the preset temperature within the preset time, so as to improve the cold survival of cells and increase the success rate of recovery of frozen human umbilical cord blood hematopoietic stem cells. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0018] Figure 1 The structural schematic diagram of the liquid nitrogen gradient cooling instrument provided by the embodiments of the present application.

[0019] Figure: 100-liquid nitrogen gradient cooling instrument; 110-tank body; 111-bearing table; 1111-temperature measuring element; 112-pressure sensor; 113-lifting shaft; 114-conveying belt; 115-drainage port; 1151-emergency drainage valve; 116-heat preservation layer; 117-supporting seat; 118-cover; 120-liquid nitrogen conveying assembly; 121-liquid nitrogen tank; 122-pipeline; 1221-control switch; 130-controller; 131-linear driver. DETAILED DESCRIPTION

[0020] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will be combined with the accompanying drawings to make a clear and complete description of the technical solutions in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. The components of the embodiments of the present application described and shown in the accompanying drawings can be arranged and designed in various different configurations.

[0021] In the description of the present application, it should be understood that the terms indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0022] It should be noted that: similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0023] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above-mentioned terms in the present application can be understood according to the specific circumstances.

[0024] Please refer to Figure 1 The liquid nitrogen gradient cooling instrument 100 provided by the embodiments of the present application comprises a tank body 110 and a liquid nitrogen conveying assembly 120 in communication with the bottom of the tank body 110. The liquid nitrogen conveying assembly 120 comprises a liquid nitrogen tank 121 and a pipeline 122 in communication with the liquid nitrogen tank 121 and the tank body 110. A control switch 1221 is further arranged on the pipeline 122. A bearing table 111 and a linear driver 131 for driving the bearing table 111 to move vertically are arranged in the tank body 110. A pressure sensor 112 is further arranged in the tank body 110. The liquid nitrogen gradient cooling instrument 100 further comprises a controller 130 arranged on the tank body 110. The controller 130 is electrically connected with the linear driver 131, the control switch 1221, the pressure sensor 112 and a temperature measuring element 1111 respectively, for controlling the working of the linear driver 131 according to the temperature signal, and controlling the opening and closing of the control switch 1221 according to the pressure signal of the pressure sensor 112.

[0025] Specifically, the tank body 110 is connected with the liquid nitrogen tank 121 through the pipeline 122, and the control switch 1221 is arranged on the pipeline 122. When the control switch 1221 is opened, the pipeline 122 between the tank body 110 and the liquid nitrogen tank 121 is opened, so that the liquid nitrogen can be input into the tank body 110. When the control switch 1221 is closed, the pipeline 122 between the tank body 110 and the liquid nitrogen tank 121 is blocked, so that the liquid nitrogen cannot enter the tank body 110, thereby more conveniently controlling the liquid nitrogen to enter or discharge the tank body 110. The bearing table 111 and the linear driver 131 for driving the bearing table 111 to move in the vertical direction are arranged in the tank body 110. The bearing table 111 and the linear driver 131 are in a vertical structure in the same plane, and the linear driver 131 can drive the bearing table 111 to move up and down in the vertical direction. The pressure sensor 112 is also arranged in the tank body 110. The liquid nitrogen gradient cooling instrument 100 further comprises the controller 130 arranged on the tank body 110. The controller 130 is electrically connected with the linear driver 131, the control switch 1221, the pressure sensor 112 and the temperature measuring element 1111 respectively, for controlling the working of the linear driver 131 according to the temperature signal, and controlling the opening and closing of the control switch 1221 according to the pressure signal of the pressure sensor 112.

[0026] It should be noted that first, in the embodiment of the present application, the tank body 110 is connected with the liquid nitrogen tank 121 through the pipeline 122, and the control switch 1221 is arranged on the pipeline 122. Such a connection mode can fully guide the liquid nitrogen in the liquid nitrogen tank 121 into the tank body 110, and the control switch 1221 is more convenient for controlling the volume of the input liquid nitrogen according to the real-time temperature and the required temperature, so that the freezing effect reaches the best.

[0027] Second, in the embodiment of the present application, the bearing table 111 and the linear driver 131 for driving the bearing table 111 to move in the vertical direction are arranged in the tank body 110. Such a setting can effectively control the position movement of the bearing table 111, and move the bearing table 111 to the space where the preset temperature is located, so that the freezing effect reaches the best.

[0028] The linear driver 131 has the function of driving the bearing table 111 to move up and down in the vertical direction, and provides the driving force for driving the bearing table 111 to move up and down in the vertical direction. In the embodiment of the present application, the specific type of the linear driver 131 is not specifically limited. For example, the linear driver 131 can be a lifting motor, a rotary motor, a cylinder, a hydraulic cylinder, a linear motor, etc. The lifting motor is described as an example of realizing the linear driver 131 in the specification, and should not be understood as a specific limitation of the linear driver 131. As long as the linear driver 131 can drive the bearing table 111 to move up and down in the vertical direction.

[0029] Third, in the embodiments of the present application, the pressure sensor 112 is further arranged in the tank body 110, and the liquid nitrogen gradient cooling instrument 100 further comprises a controller 130 arranged on the tank body 110, and the controller 130 is electrically connected with the linear driver 131, the control switch 1221, the pressure sensor 112 and the temperature measuring element 1111 respectively. Such arrangement can enable the operator to artificially set the temperature that the specimen needs to reach at a predetermined time, and can also master the temperature of the environment where the carrying table 111 is located in the tank body 110 in real time through various sensors and detectors, and then transmit the temperature signal to the controller 130, and control the linear driver 131 to drive the carrying table 111 to move in the vertical direction according to the preset temperature.

[0030] Fourth, in the embodiments of the present application, the temperature measuring element 1111 is arranged on the surface of the carrying table 111, and before gradient cooling, the temperature measuring element 1111 is inserted into the frozen bag (standard bag), so as to accurately simulate the bag temperature of the specimen to be preserved placed on the carrying table 111. The temperature measuring element 1111 detects the temperature in the standard bag and transmits the temperature signal to the controller 130, and the controller 130 adjusts the position of the carrying table 111 in the vertical direction according to the preset temperature, so as to change the cooling speed of the specimen to be preserved. The temperature measuring element 1111 is electrically connected with the controller 130, and when the carrying table 111 moves in the vertical direction with the linear driver 131, the environmental temperature of the specimen to be preserved also changes in gradient.

[0031] Through the arrangement of the temperature measuring element 1111, the bag temperature in the specimen to be preserved can be simulated by detecting the temperature in the standard bag through the method of setting a reference, so as to protect the cells in the specimen to be preserved to the greatest extent, and the real-time temperature of the environment where the carrying table 111 is located is intuitively detected, and then the specimen to be preserved can smoothly reach the preset temperature within the preset time, so that the freezing effect is optimal.

[0032] The liquid nitrogen gradient cooling instrument 100 provided by the embodiment of the present application comprises a tank body 110 and a liquid nitrogen conveying assembly 120 in communication with the bottom of the tank body 110. The liquid nitrogen conveying assembly 120 comprises a liquid nitrogen tank 121 and a pipeline 122 in communication with the liquid nitrogen tank 121 and the tank body 110. A control switch 1221 is arranged on the pipeline 122, so that the liquid nitrogen can be more conveniently controlled to enter or discharge the tank body 110. The tank body 110 is internally provided with a bearing table 111 and a linear driver 131 for driving the bearing table 111 to move in the vertical direction. The bearing table 111 is arranged to be more convenient for placing the to-be-preserved piece. The linear driver 131 is arranged to effectively control the movement of the bearing table 111 in the vertical direction, so as to control the to-be-preserved piece to smoothly reach the preset temperature within the preset time. The tank body 110 is further provided with a pressure sensor 112. The pressure value detected by the pressure sensor 112 is convenient for knowing the volume of the liquid nitrogen in the tank body 110. The liquid nitrogen gradient cooling instrument 100 further comprises a controller 130 arranged on the tank body 110. The controller 130 is electrically connected with the linear driver 131, the control switch 1221 and the pressure sensor 112, respectively, for controlling the working of the linear driver 131 according to the temperature signal and controlling the opening and closing of the control switch 1221 according to the pressure signal of the pressure sensor 112. When the liquid nitrogen gradient cooling instrument 100 is actually operated, the operator can first preset the temperature and time by the device, can directly observe the real-time temperature of the environment in which the to-be-preserved piece is located, can transmit the temperature signal to the controller 130, can control the linear driver 131 to drive the bearing table 111 to move in the vertical direction according to the preset temperature, and can further control the to-be-preserved piece to smoothly reach the preset temperature within the preset time, so as to improve the cold survival of the cells and increase the success rate of the recovery of the frozen human umbilical cord blood hematopoietic stem cells.

[0033] In an implementable embodiment of the present application, as shown in Figure 1 The pressure sensor 112 is arranged at the bottom of the tank body 110. The pressure value detected by the pressure sensor 112 is positively correlated with the volume of the liquid nitrogen in the tank body 110.

[0034] Specifically, the pressure sensor 112 is electrically connected with the bottom of the tank body 110. When the volume of the liquid nitrogen in the tank body 110 increases, the pressure value detected by the pressure sensor 112 is greater. When the volume of the liquid nitrogen in the tank body 110 decreases, the pressure value detected by the pressure sensor 112 is smaller.

[0035] Through the arrangement of the pressure sensor 112, the pressure value can be directly detected, so as to know the volume of the liquid nitrogen in the tank body 110, to control the working of the linear driver 131 and to control the opening and closing of the control switch 1221 according to the pressure signal of the pressure sensor 112.

[0036] In an implementable embodiment of the present application, as shown inFigure 1 As shown, the liquid nitrogen conveying assembly 120 pipe 122 is communicated with the tank body 110 at the bottom of the tank body 110.

[0037] Specifically, one end of the liquid nitrogen input assembly pipe 122 is connected to the tank body 110 at the bottom of the tank body 110, and the other end of the liquid nitrogen input assembly pipe 122 is communicated with the liquid nitrogen tank 121. When the liquid nitrogen in the liquid nitrogen tank 121 enters the tank body 110 through the liquid nitrogen input assembly pipe 122, the liquid nitrogen will first gather at the bottom of the tank body 110 and gradually spread to the upper part of the tank body 110.

[0038] By connecting the liquid nitrogen input assembly pipe 122 with the bottom of the tank body 110, the liquid nitrogen in the liquid nitrogen tank 121 can be introduced into the tank body 110, and the low-temperature liquid nitrogen will gather at the bottom of the tank body 110 and gradually spread to the upper part of the tank body 110, gradually forming a temperature gradient from bottom to top, facilitating changing the vertical position of the support platform 111 according to the temperature requirement.

[0039] As shown in the example, Figure 1 As shown, the tank body 110 is vertically provided with a lifting shaft 113 in the center, and the support platform 111 is horizontally arranged on the lifting shaft 113, and the support platform 111 moves on the lifting shaft 113 through a linear driver 131.

[0040] Specifically, the center of the tank body 110 is vertically provided with a lifting shaft 113, and the support platform 111 is horizontally arranged on the lifting shaft 113, and the support platform 111 and the lifting shaft 113 are vertically arranged in the same plane, and the linear driver 131 is electrically connected with the lifting shaft 113, and under the driving of the linear driver 131, the lifting shaft 113 and the support platform 111 move up and down in the vertical direction of the lifting shaft 113.

[0041] By horizontally arranging the support platform 111 and the lifting shaft 113, the movement of the lifting platform in the vertical direction can be driven by the linear driver 131, and then the real-time temperature of the environment and the preset temperature can be matched to make the refrigeration effect optimal.

[0042] As shown in the example, Figure 1 As shown, the liquid nitrogen gradient cooling instrument 100 further comprises a conveyor belt 114 connecting the linear driver 131 and the support platform 111, and the linear driver 131 drives the support platform 111 to lift through the conveyor belt 114.

[0043] Specifically, one end of the conveyor belt 114 is connected to the linear driver 131, and the other end is connected to the support platform 111, and when the linear driver 131 operates, the conveyor belt 114 drives the support platform 111 to lift.

[0044] It should be noted that the function of the conveyor belt 114 is to connect the bearing table 111 and the linear driver 131, so that the bearing table 111 is driven by the linear driver 131 through the connection effect of the conveyor belt 114. In the embodiment of the present application, the form of the conveying device is not limited, and in addition to using the conveyor belt 114, a conveying chain or other device can also be used, as long as the conveying device can drive the bearing table 111 to move up and down in the vertical direction.

[0045] By building the conveyor belt 114 between the top of the tank body 110 and the bearing table 111, the up and down movement of the bearing table 111 driven by the conveyor belt under the driving of the linear driver 131 can be facilitated, so that the temperature of the to-be-preserved member can be controlled to reach the preset temperature smoothly within the preset time, thereby improving the success rate of the recovery of the cryopreserved human umbilical cord blood hematopoietic stem cells.

[0046] In an implementable embodiment of the present application, as shown in Figure 1 The bottom of the tank body 110 is also provided with a liquid discharge port 115, and the liquid discharge port 115 is connected with an emergency liquid discharge valve 1151.

[0047] Specifically, the bottom of the tank body 110 is provided with a liquid discharge port 115, so that the liquid nitrogen in the tank can flow out; the liquid discharge port 115 is connected with an emergency liquid discharge valve 1151, when the valve is opened, the liquid nitrogen can flow out from the liquid discharge port 115, and when the valve is closed, the liquid nitrogen is blocked and cannot flow out from the liquid discharge port 115.

[0048] By setting the emergency liquid discharge valve 1151, the problem that the amount of liquid nitrogen cannot be controlled due to equipment failure in the tank and other factors is avoided, and safety protection is provided for the to-be-preserved member.

[0049] As shown in Figure 1 The inner wall of the tank body 110 is provided with a heat preservation layer 116.

[0050] Specifically, the tank wall of the tank body 110 is double-layered, and the inner wall of the tank body 110 is provided with a heat preservation layer 116, which isolates the liquid nitrogen from the outer wall of the tank body 110.

[0051] By setting the heat preservation layer 116 on the inner wall of the tank body 110, the liquid nitrogen is isolated from the outer wall of the tank body 110, so that the temperature in the tank is stable and is not easily affected by the external temperature, thereby improving the success rate of the recovery of the cryopreserved human umbilical cord blood hematopoietic stem cells.

[0052] In an implementable embodiment of the present application, as shown in Figure 1 The bottom of the tank body 110 is provided with a support seat 117.

[0053] Specifically, the bottom of the tank body 110 is provided with two support seats 117, which are welded with the bottom of the tank body 110. The welding method has better connection stability, and the welding difficulty is not high, which is easy to process on a large base structure. The structure stability and stress bearing capacity of the two structures welded in multiple directions are better, so that the overall structure of the liquid nitrogen gradient cooling instrument 100 connected in this way is more stable and firm. The bottom of the support seat 117 is rectangular, which increases the contact area with the ground and makes the stability of the entire liquid nitrogen gradient cooling instrument 100 higher.

[0054] Through the setting of the support seat 117 at the bottom of the tank body 110, the overall structure of the liquid nitrogen gradient cooling instrument 100 is more stable and firm, the stability of the entire liquid nitrogen gradient cooling instrument 100 is higher, and the safety of the preserved parts during the freezing process is improved.

[0055] In an implementable embodiment of the present application, as shown in Figure 1 The top of the tank body 110 is also provided with an opening, and a cover 118 is rotatably arranged on the tank body 110, which can be covered on the opening by rotation.

[0056] Specifically, the top of the tank body 110 has an opening, which is used in cooperation with the cover 118, and the cover 118 covers the opening by rotating.

[0057] Through the setting of the opening and the cover 118, the inside of the tank body 110 is communicated with the outside, which is convenient for the preserved parts to enter or take out the inside of the tank body 110.

[0058] In an implementable embodiment of the present application, the tank body 110 is also provided with a display panel (not shown in the figure), which is electrically connected with the controller 130.

[0059] Specifically, the display panel is arranged on the outer surface of the tank body 110 and is electrically connected with the controller 130, so as to directly display the related data of the current tank environment.

[0060] Through the setting of the display panel, the user can directly know the related data of the current tank environment, such as the pressure value and the real-time temperature at the height of the bearing table 111, so as to make further adjustment according to the specific situation.

[0061] The above is only an embodiment of the present application and is not used to limit the protection scope of the present application. For those skilled in the art, the present application can have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A liquid nitrogen gradient cooling device, characterized in that, The device includes a tank and a liquid nitrogen delivery assembly connected to the bottom of the tank. The liquid nitrogen delivery assembly includes a liquid nitrogen tank and a pipe connecting the liquid nitrogen tank and the tank. A control switch is also provided on the pipe. A support platform and a linear actuator for driving the support platform to move vertically are provided inside the tank. A pressure sensor is also provided inside the tank. The liquid nitrogen gradient cooling device also includes a controller provided on the tank. The controller is electrically connected to the linear actuator, the control switch, the pressure sensor, and the temperature measuring element, respectively, and is used to control the operation of the linear actuator according to the temperature signal, and to control the opening and closing of the control switch according to the pressure signal from the pressure sensor. The temperature sensing element is installed on the surface of the support platform. Before gradient cooling, the temperature sensing element is inserted into a freezing bag to simulate the temperature inside the bag of the item to be preserved placed on the support platform. The temperature sensing element detects the temperature inside the standard bag and transmits the temperature signal to the controller. The linear actuator drives the support platform to move vertically, thereby controlling the item to be preserved to reach the preset temperature smoothly within a preset time, thus matching the real-time temperature of the environment with the preset temperature. The pressure sensor is installed at the bottom of the tank, and the pressure value detected by the pressure sensor is positively correlated with the volume of liquid nitrogen inside the tank. The liquid nitrogen delivery assembly pipeline is connected to the tank body at the bottom of the tank body; The bottom of the tank is also provided with a drain port, and an emergency drain valve is connected to the drain port; The inner wall of the tank is provided with a heat insulation layer; The top of the tank is also provided with an opening, and a cover is rotatably provided on the tank, which can be rotated to close the opening.

2. The liquid nitrogen gradient cooling device according to claim 1, characterized in that, A lifting shaft is vertically arranged at the center of the tank, and the support platform is horizontally arranged on the lifting shaft. The support platform moves on the lifting shaft through the linear drive.

3. The liquid nitrogen gradient cooling device according to claim 2, characterized in that, It also includes a conveyor belt connecting the linear drive and the carrier platform, wherein the linear drive drives the carrier platform to move up and down via the conveyor belt.

4. The liquid nitrogen gradient cooling device according to claim 1, characterized in that, A support base is provided at the bottom of the tank.

5. The liquid nitrogen gradient cooling device according to claim 1, characterized in that, The tank is also equipped with a display panel, which is electrically connected to the controller.

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