Scanning electron microscope biological sample pretreatment device
By combining liquid nitrogen freezing with vacuum removal, the problem of high energy consumption and long time in the drying technology of biological samples for scanning electron microscopy has been solved, realizing rapid and low-energy sample drying while maintaining the integrity of sample morphology.
Patent Information
- Application Number
- CN202423000501.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-06
- Publication Date
- 2025-11-11
- Estimated Expiration
- 2034-12-06
AI Technical Summary
Existing scanning electron microscopy biological sample drying techniques suffer from problems such as complex operation, high energy consumption, long drying time, and potential mechanical damage to the samples. In particular, the refrigeration methods of traditional freeze-drying equipment are not efficient enough, and the refrigerants used are not environmentally friendly.
By employing liquid nitrogen freezing combined with vacuum extraction, and by setting up a refrigeration and vacuum mechanism inside the drying container, the biological samples are frozen with liquid nitrogen and the freezing medium is sublimated under a high vacuum environment, which shortens the drying time and reduces energy consumption.
It enables rapid drying of biological samples, reducing drying time to within 1 hour, lowering energy consumption, minimizing mechanical damage to the samples, and maintaining the integrity of the sample morphology.
Smart Images
Figure CN223538804U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of scanning electron microscopy biological sample drying technology, and in particular to a scanning electron microscopy biological sample pretreatment device. Background Technology
[0002] Biological samples are characterized by high water content and poor conductivity. They must be dehydrated and dried before being observed by scanning electron microscopy. During the process, sample deformation caused by water removal should be minimized.
[0003] Common dehydration and drying methods for biological samples include CO2 critical point drying and freeze-drying. CO2 critical point drying requires meticulous operation; improper handling of even minor steps can lead to drying failure. Furthermore, the numerous steps involved can cause irreversible mechanical damage to the biological sample. Freeze-drying, depending on the freezing medium used, is divided into direct freeze-drying from water and freeze-drying from organic solvents. Compared to water, organic solvents have a higher chance of forming amorphous structures and a lower chance of solid-phase recrystallization during freezing, reducing damage to the biological sample from ice crystals. Additionally, they can sublimate from the solid phase at a faster rate, significantly shortening the drying time. Under freezing and low-vacuum conditions, organic solvents sublimate directly from the solid phase without passing through a liquid stage, thus avoiding damage to the biological sample caused by surface tension between the gas and liquid phases during the drying process.
[0004] Freeze-drying is based on a combination of vacuum and freezing technologies. Its key points are: first, the biological sample is frozen at a temperature below the eutectic point of the sample, and then transferred to a vacuum environment, so that the ice crystals in the biological sample directly sublimate, thereby removing moisture and achieving the purpose of drying.
[0005] Most existing freeze-drying equipment uses either compressor refrigeration or semiconductor refrigeration. Compressor refrigeration uses fluorine-containing refrigerants, which are unfriendly to the environment and laboratory personnel. Compressor refrigeration also suffers from high noise, high energy consumption, and poor cooling effect. Semiconductor refrigeration requires supporting equipment to solve the problem of hot-end heat dissipation, because the cooling efficiency of semiconductor refrigeration is related to the speed of hot-end heat dissipation. Hot-end heat dissipation is mostly achieved through air cooling, heat pipe heat transfer, circulating water, etc., resulting in a large number of components, complex structure, long drying time, and high energy consumption, making it unsuitable for drying biological samples for scanning electron microscopy. Utility Model Content
[0006] The purpose of this invention is to provide a scanning electron microscope (SEM) biological sample pretreatment device to solve the problems existing in the above-mentioned related technologies. It can dry SEM biological samples with short drying time and low energy consumption.
[0007] To achieve the above objectives, this utility model provides the following solution:
[0008] This invention provides a scanning electron microscope biological sample pretreatment device, including a drying container, a refrigeration mechanism, and a vacuum mechanism. The drying container is capable of holding biological samples. The refrigeration mechanism is disposed inside the drying container and is capable of freezing the biological samples inside the drying container with liquid nitrogen. The vacuum mechanism is connected to the drying container and is capable of evacuating the drying container to dry the frozen biological samples inside the drying container.
[0009] Preferably, the drying container includes a sample stage, a base, and a vacuum hood. The sample stage is disposed on the base, the vacuum hood covers the sample stage and is sealed to the base, and the vacuum hood is provided with a pressure relief section.
[0010] Preferably, the pressure relief part is a pressure relief cap, which is threadedly connected to the top of the vacuum shroud.
[0011] Preferably, the drying container further includes an O-ring, which is disposed on the base to seal the connection between the vacuum hood and the base.
[0012] Preferably, the refrigeration mechanism includes a liquid nitrogen storage tank, which is an annular tank structure and can be filled with liquid nitrogen; the liquid nitrogen storage tank is disposed on the sample stage, and the sample stage is positioned within the liquid nitrogen storage tank to accommodate a sample tray containing the biological sample.
[0013] Preferably, the vacuum mechanism includes a connecting block, a vacuum pipeline, and a vacuum pump. The connecting block is disposed at the bottom of the base, and a first gas channel runs through the connecting block. A second gas channel runs through the base. One end of the first gas channel is connected to the drying container through the second gas channel, and the other end is connected to the air inlet of the vacuum pump through the vacuum pipeline.
[0014] Preferably, the vacuum mechanism further includes a vacuum gauge and a valve, the vacuum gauge being connected to the first gas channel to measure the vacuum level inside the drying container; the valve being disposed on the vacuum pipeline.
[0015] Preferably, a temperature detector is also installed inside the drying container.
[0016] Preferably, the scanning electron microscope biological sample pretreatment device further includes a heating mechanism disposed inside the drying container, the heating mechanism being capable of heating the drying container.
[0017] Preferably, the heating mechanism is an electric heating rod.
[0018] This utility model achieves the following technical advantages compared to related technologies:
[0019] The scanning electron microscope biological sample pretreatment device provided by this utility model includes a drying container, a refrigeration mechanism, and a vacuum mechanism. In use, the biological sample with organic solvent as the freezing medium is placed in the drying container. The biological sample is frozen with liquid nitrogen by the refrigeration mechanism to quickly achieve vitrification or crystallization of the freezing medium. The drying container is evacuated by the vacuum mechanism, and the freezing medium is sublimated quickly in a high vacuum environment, thereby achieving the drying of the biological sample. The drying time is short and the energy consumption is low. Attached Figure Description
[0020] To more clearly illustrate the technical solutions in the embodiments of this utility model or related technologies, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0021] Figure 1 A schematic diagram of the scanning electron microscope biological sample pretreatment device provided in an embodiment of this utility model;
[0022] Figure 2 This is a schematic diagram of the drying container and connecting block provided in an embodiment of the present utility model.
[0023] In the diagram: 1-Drying container, 2-Sample stage, 3-Base, 301-Second gas channel, 4-Vacuum hood, 5-Pressure relief cap, 6-O-ring seal, 7-Liquid nitrogen storage tank, 8-Connecting block, 801-First gas channel, 9-Vacuum pipeline, 10-Vacuum pump, 11-Vacuum gauge, 12-Valve, 13-Temperature detector, 14-Electric heating rod. Detailed Implementation
[0024] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.
[0025] The purpose of this invention is to provide a scanning electron microscope (SEM) biological sample pretreatment device to solve the problems existing in related technologies. This device can dry SEM biological samples with short drying time and low energy consumption.
[0026] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0027] like Figures 1-2 As shown, this embodiment provides a scanning electron microscope biological sample pretreatment device, including a drying container 1, a refrigeration mechanism, and a vacuum mechanism. The drying container 1 can contain biological samples; the refrigeration mechanism is disposed inside the drying container 1 and can freeze the biological samples inside the drying container 1 with liquid nitrogen; the vacuum mechanism is connected to the drying container 1 and can evacuate the drying container 1 to dry the frozen biological samples inside the drying container 1.
[0028] In this embodiment, the drying container 1 includes a sample stage 2, a base 3, and a vacuum hood 4. The sample stage 2 is disposed on the base 3, and the vacuum hood 4 can cover the sample stage 2 and is sealed to the base 3. The top of the vacuum hood 4 is threaded with a pressure relief cap 5. Specifically, the sample stage 2 in this embodiment is composed of an aluminum tabletop and a metal support column, wherein the metal support column is covered with a PVC foam layer. The vacuum hood 4 in this embodiment is preferably an acrylic vacuum hood, which facilitates observation of the internal condition of the drying container 1.
[0029] In this embodiment, the drying container 1 also includes an O-ring 6, which is disposed on the base 3 to seal the position where the vacuum cover 4 is connected to the base 3.
[0030] In this embodiment, the cooling mechanism includes a liquid nitrogen storage tank 7, which is an annular tank structure and can be filled with liquid nitrogen. The liquid nitrogen storage tank 7 is set on the sample stage 2, and a sample tray containing biological samples can be accommodated at a position on the sample stage 2 inside the liquid nitrogen storage tank 7. By designing an annular liquid nitrogen storage structure inside the drying container 1, liquid nitrogen is directly used for cooling. As the vacuum level gradually decreases, the liquid nitrogen also forms liquid nitrogen sludge, further ensuring the extremely low temperature environment inside the drying container 1 and ensuring that the organic solvent remains in a solid state or a glassy state.
[0031] In this embodiment, the vacuum mechanism includes a connecting block 8, a vacuum pipeline 9, and a vacuum pump 10. The connecting block 8 is located at the bottom of the base 3, and a first gas channel 801 passes through the connecting block 8. A second gas channel 301 passes through the base 3. One end of the first gas channel 801 is connected to the drying container 1 through the second gas channel 301, and the other end is connected to the air inlet of the vacuum pump 10 through the vacuum pipeline 9. The vacuum pump 10 can evacuate the drying container 1, achieving high vacuum conditions and greatly shortening the drying time.
[0032] In this embodiment, the vacuum mechanism also includes a vacuum gauge 11 and a valve 12. The vacuum gauge 11 is connected to the first gas channel 801 to measure the vacuum level inside the drying container 1; the valve 12 is disposed on the vacuum pipeline 9.
[0033] In this embodiment, a temperature detector 13 is also provided inside the drying container 1 to detect the temperature inside the drying container 1.
[0034] In this embodiment, the scanning electron microscope biological sample pretreatment device also includes a heating mechanism, which is disposed inside the drying container 1 and can heat the drying container 1.
[0035] Furthermore, the heating mechanism is an electric heating rod 14. In this embodiment, the electric heating rod 14 is preferably a 48V miniature electric heating rod. The electric heating rod 14 is embedded in the sample stage 2. After the biological sample is freeze-dried, the electric heating rod 14 can achieve rapid heating, ensuring that the biological sample does not become damp due to low temperature after the vacuum hood 4 is opened to release the pressure.
[0036] The usage process of the scanning electron microscope biological sample pretreatment device provided in this embodiment is as follows:
[0037] Step 1: Fix the biological sample, dehydrate it stepwise with ethanol, replace it with 100% tert-butanol, place it in a sample tray and let it stand.
[0038] Step 2: Slowly inject liquid nitrogen into liquid nitrogen storage tank 7 until the liquid nitrogen no longer emits white gas. The amount of liquid nitrogen is determined according to the amount of biological sample.
[0039] Step 3: Place the sample tray containing the biological sample on sample stage 2.
[0040] Step 4: Cover with vacuum hood 4; open valve 12.
[0041] Step 5: Turn on the power; vacuum pump 10 starts working, temperature detector 13 displays -200 degrees Celsius, and liquid nitrogen forms liquid nitrogen sludge.
[0042] Step six: At this point, the vacuum level inside the drying container 1 drops rapidly. After about 3-5 minutes, the reading of the vacuum gauge 11 is maintained at around 100 Pa.
[0043] Step 7: Solid tert-butanol and solid liquid nitrogen gradually sublimate, and the gas in the drying container 1 is removed by vacuum pump 10. The whole process takes about 0.5-1 hour (the time is relatively longer if there is a large amount of biological sample).
[0044] Step 8: The reading of vacuum gauge 11 drops to below 10 Pa, and the reading remains unchanged, indicating that the biological sample is dried.
[0045] Step 9: Turn on the electric heating rod 14 and gradually heat it to room temperature.
[0046] Step 10: Turn off vacuum pump 10, unscrew pressure relief cap 5, open vacuum hood 4, and remove biological sample. Alternatively, to preserve biological sample, close valve 12 before turning off vacuum pump 10, and then turn off vacuum pump 10 to maintain vacuum for a longer period and prevent moisture absorption.
[0047] In summary, this device enables time-saving and labor-saving sample pretreatment processes that more closely resemble the morphology of the biological organism. This device offers the following advantages:
[0048] First, traditional methods of achieving chamber cooling using circulating water and semiconductor refrigeration suffer from incomplete cooling (cooling temperatures are generally between -20 and -50°C), high energy consumption, and long cooling time. In contrast, this device uses liquid nitrogen refrigeration directly within a vacuum chamber, achieving a cooling temperature of -210°C. This allows for rapid vitrification or crystallization of the freezing medium, resulting in thorough cooling with low energy consumption. Furthermore, the extremely low temperature in a vacuum environment allows the freezing medium to exhibit other previously unreported crystallization patterns, making it more suitable for preserving the morphology of biological samples.
[0049] Secondly, traditional devices are complex in structure, control system and operation in order to maintain low temperature. However, this application designs a ring-shaped liquid nitrogen storage structure and combines it with a high-efficiency vacuum pump 10. By utilizing the special form and sublimation properties of the freezing medium in a high vacuum and extremely low temperature environment, biological sample drying is achieved better. Compared with the drying time of about 6-8 hours of traditional semiconductor refrigeration, the drying time is shortened to less than 1 hour by using this device, which greatly reduces the drying time, and the operation steps are fewer, saving time and effort.
[0050] This utility model uses specific examples to illustrate its principles and implementation methods. The above description of the embodiments is only for the purpose of helping to understand the method and core idea of this utility model. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the idea of this utility model. In summary, the content of this specification should not be construed as a limitation of this utility model.
Claims
1. A scanning electron microscope biological sample pretreatment device, characterized in that: The device includes a drying container, a refrigeration mechanism, and a vacuum mechanism. The drying container is capable of holding biological samples. The refrigeration mechanism is disposed inside the drying container and is capable of freezing the biological samples inside the drying container with liquid nitrogen. The vacuum mechanism is connected to the drying container and is capable of evacuating the drying container to dry the frozen biological samples inside the drying container.
2. The scanning electron microscope biological sample pretreatment device according to claim 1, characterized in that: The drying container includes a sample stage, a base, and a vacuum hood. The sample stage is disposed on the base, and the vacuum hood can cover the sample stage and is sealed to the base. The vacuum hood is provided with a pressure relief section.
3. The scanning electron microscope biological sample pretreatment device according to claim 2, characterized in that: The pressure relief part is a pressure relief cap, which is threadedly connected to the top of the vacuum shroud.
4. The scanning electron microscope biological sample pretreatment device according to claim 2, characterized in that: The drying container also includes an O-ring, which is disposed on the base to seal the connection between the vacuum hood and the base.
5. The scanning electron microscope biological sample pretreatment device according to claim 2, characterized in that: The refrigeration mechanism includes a liquid nitrogen storage tank, which is an annular tank structure and can be filled with liquid nitrogen; the liquid nitrogen storage tank is disposed on the sample stage, and the sample stage is positioned within the liquid nitrogen storage tank to accommodate a sample tray containing the biological sample.
6. The scanning electron microscope biological sample pretreatment device according to claim 2, characterized in that: The vacuum mechanism includes a connecting block, a vacuum pipeline, and a vacuum pump. The connecting block is located at the bottom of the base and has a first gas channel running through it. The base has a second gas channel running through it. One end of the first gas channel is connected to the drying container through the second gas channel, and the other end is connected to the air inlet of the vacuum pump through the vacuum pipeline.
7. The scanning electron microscope biological sample pretreatment device according to claim 6, characterized in that: The vacuum mechanism also includes a vacuum gauge and a valve. The vacuum gauge is connected to the first gas channel to measure the vacuum level inside the drying container; the valve is located on the vacuum pipeline.
8. The scanning electron microscope biological sample pretreatment device according to claim 1, characterized in that: The drying container is also equipped with a temperature detector.
9. The scanning electron microscope biological sample pretreatment device according to claim 1, characterized in that: The scanning electron microscope biological sample pretreatment device also includes a heating mechanism, which is disposed inside the drying container and is capable of heating the drying container.
10. The scanning electron microscope biological sample pretreatment device according to claim 9, characterized in that: The heating mechanism is an electric heating rod.