A gas-liquid two-phase in-situ observation sample rod for a transmission electron microscope and an observation cleaning method

Abstract

The application discloses a kind of gas-liquid two-phase in-situ observation sample rod for transmission electron microscope and observation cleaning method, belong to transmission electron microscope in-situ experimental technical field.The sample rod includes front end sample table area, stem and hand grip connected in sequence;The front end sample table area forms rod head vacuum cavity, and there are gas phase and liquid phase observation chip in cavity along sample rod axis direction in series.The internal sample rod is provided with independent vacuum pipeline and fluid transmission pipeline, wherein fluid transmission pipeline is used to transport gas or liquid sample into chip, and vacuum pipeline is used to maintain the vacuum degree of rod head vacuum cavity throughout the process to protect the observation area of chip;At the same time, by injecting inert gas and cleaning agent in fluid transmission pipeline in turn, the observation area is cleaned.The application does not need to repeatedly plug and pull sample rod, has the advantages of fast fluid control response, cleaning without dead angle, preventing cross contamination and high vacuum safety.

Description

Technical Field

[0001] This invention belongs to the field of in-situ experimental technology of transmission electron microscopy, specifically relating to a gas-liquid two-phase in-situ observation sample rod for transmission electron microscopy and an observation and cleaning method. Background Technology

[0002] Transmission electron microscopy (TEM) is an important characterization tool in materials science, chemistry, biology, and physics, possessing high-resolution imaging capabilities at the atomic scale. With the development of in-situ electron microscopy, researchers hope to observe the structural evolution, chemical reactions, and interfacial behavior of materials in real-time in real reaction environments (such as gases or liquids), thereby gaining a deeper understanding of their dynamic processes.

[0003] Currently, various gas-phase and liquid-phase in-situ sample holders have been developed to meet the in-situ experimental requirements of transmission electron microscopy. Gas-phase sample holders typically use a sealed cavity and gas flow structure to control the atmosphere; liquid-phase sample holders are mostly based on microelectromechanical systems (MEMS) chips, using a silicon nitride transparent window on the chip to encapsulate the liquid sample in a microcavity, allowing the electron beam to penetrate and be observed.

[0004] However, existing technologies still have the following prominent problems: (1) Limited functionality and inconvenient switching: Commercial in-situ sample holders typically only support observation of a single phase (gas or liquid). If gas-liquid contrast studies or switching reaction environments are required, it is often necessary to remove the sample holder from the electron microscope, replace the chip, or even replace the entire sample holder. This process not only interrupts the experiment and makes it difficult to find the same observation field, but also repeatedly damages the vacuum of the electron microscope, introducing the risk of contamination.

[0005] (2) Sample replacement relies on insertion and removal: Traditional sample rods need to be pulled out of the electron microscope when changing samples, which is cumbersome and frequent insertion and removal can easily lead to leakage of the vacuum chamber, affecting the stability of the equipment and experimental efficiency.

[0006] (3) Difficult to clean and prone to cross-contamination: Especially in liquid phase or multi-reagent experiments, the microflow path and reaction chamber are prone to residues of the previous sample or reagent. Due to the limitations of the laminar flow effect at the micro-nano scale, conventional rinsing is difficult to completely remove the residues in dead corners, leading to cross-contamination or artifacts in subsequent experiments.

[0007] (4) Vacuum system is susceptible to interference: Some designs couple the vacuum pumping channel with the fluid discharge channel. Liquid evaporation will significantly slow down the vacuum establishment speed, increase the vacuum pumping time, and reduce experimental efficiency.

[0008] (5) Fluid control lag: The control valve is usually placed outside the sample rod handle. The pipeline between the valve chip is long and the "dead volume" is large, which leads to slow fluid replacement and sluggish response, making it difficult to achieve rapid and accurate control of reaction conditions.

[0009] (6) Safety hazards: If the MEMS window breaks, the high-pressure gas or liquid inside the cavity may leak into the electron microscope vacuum chamber instantly, posing a threat to the expensive equipment.

[0010] Therefore, there is an urgent need for a transmission electron microscope sample holder that can integrate gas phase and liquid phase observation functions in the same sample holder, support online sample replacement, have efficient in-situ cleaning capabilities, and ensure vacuum isolation and operational safety, in order to overcome the above-mentioned technical bottlenecks. Summary of the Invention

[0011] The purpose of this invention is to provide a gas-liquid two-phase in-situ observation sample holder and observation cleaning method for transmission electron microscopy, so as to solve the problems of separation of gas phase and liquid phase observation, repeated insertion and removal of sample replacement, low cleaning efficiency, vacuum system being susceptible to liquid interference, slow fluid control response, and insufficient safety in the prior art.

[0012] To achieve the above objectives, the present invention adopts the following technical solution: A sample holder for in-situ observation of gas-liquid two-phase transmission electron microscopy includes a front sample stage, a shaft, and a handle connected in sequence.

[0013] The front-end sample stage area includes an outer casing. Inside the outer casing, two through holes are arranged side-by-side along the axis of the sample rod. A gas phase observation MEMS chip and a liquid phase observation MEMS chip are respectively installed in the two through holes. SiN visualization windows are arranged opposite each other on the top and bottom of each chip for observation by transmission electron beam. Slits are provided on the walls of the two through holes, and the SiN visualization windows are sealed and embedded in the slits by sealing rings. A rod head vacuum cavity is provided around the two through holes to form a vacuum shield around the chip. The sample rod is internally equipped with a fluid delivery system and a vacuum pipeline. The fluid delivery system includes at least one gas phase input / output pipeline and one liquid phase input / output pipeline, which are independent of each other from the vacuum pipeline. The gas phase observation MEMS chip is located on the gas phase input / output pipeline, and the liquid phase observation MEMS chip is located on the liquid phase input / output pipeline. The fluid delivery system is connected to an external pumping system and a recovery device to deliver gas phase samples and / or liquid phase samples, respectively or selectively, into the micro-reaction chambers of the gas phase observation MEMS chip and the liquid phase observation MEMS chip, and to discharge waste liquid and waste gas. The axis of the vacuum pipeline coincides with the axis of the sample rod and connects the external vacuum device to the vacuum chamber at the rod head. It is used to maintain the vacuum level of the vacuum chamber at the rod head and to aspirate leaked samples when the seal between the SiN visualization window and the sealing ring fails, preventing contamination of the electron microscope.

[0014] Preferably, a micro-valve control module is provided inside the rod body at a distance of 10-20 mm from the front end face of the rod body. This module is used to control the inflow rate of gas phase and liquid phase samples, while preventing the backflow of waste gas and waste liquid. The micro-valve control module includes a gas phase feed valve, a liquid phase feed valve, a gas phase waste discharge valve, and a liquid phase waste discharge valve. The gas phase feed valve and the gas phase waste discharge valve are arranged on the gas phase input and output pipelines, and the liquid phase feed valve and the liquid phase waste discharge valve are arranged on the liquid phase input and output pipelines.

[0015] Preferably, the gas phase observation MEMS chip is located near the electron beam incident side, and the liquid phase observation MEMS chip is located behind the gas phase observation MEMS chip. By mechanically shifting the electron beam transmission area through the electron microscope sample stage, gas-liquid comparison studies can be achieved in the same or adjacent fields of view.

[0016] An in-situ observation cleaning method for a gas-liquid two-phase in-situ observation sample rod used in transmission electron microscopy, comprising the following steps: S1. After the sample rod is inserted into the electron microscope sample stage, the vacuum chamber of the rod head is continuously evacuated through the vacuum pipeline via an external pumping system until the preset vacuum level is reached. Then the micro valve control module is turned on. S2. A gaseous sample is injected into the gas phase input pipeline and a liquid phase sample is injected into the liquid phase input pipeline through an external pumping system. Under the regulation of the micro-valve control module, the gaseous sample enters the micro-reaction chamber of the gas phase observation MEMS chip, and the liquid phase sample enters the micro-reaction chamber of the liquid phase observation MEMS chip. The transmission electron microscope is turned on, and the electron beam penetrates from top to bottom through the upper SiN visualization window, the gas phase observation MEMS chip, and the lower SiN visualization window to perform real-time imaging of the dynamic behavior of the gaseous sample. The electron microscope sample stage is moved to perform real-time imaging of the dynamic behavior of the liquid phase sample. S3. Under the pressure difference drive, the observed waste gas is discharged through the gas phase output pipeline, and the waste liquid is discharged through the liquid phase output pipeline and collected into the external recovery device. S4. After the sample observation is completed, close the micro-valve control module and introduce inert gas into the fluid delivery system through an external gas source to purge the gas and liquid samples remaining in the pipeline and chip micro-reaction chamber to the external recovery device. S5. Inject cleaning agent into the fluid delivery system through an external pumping system, filling the micro-reaction chambers of the gas phase observation MEMS chip and the liquid phase observation MEMS chip with cleaning agent; by periodically adjusting the pressure of the external pumping system, the cleaning agent generates pulsating motion in the front sample stage area. The instantaneous shear force and pressure fluctuation generated by the pulsating motion shake off and suspend the stubborn residues, which are then discharged from the sample rod with the cleaning agent; after cleaning, inert gas is introduced into the fluid delivery system again to blow out the cleaning agent, and then the next sample loading is performed.

[0017] Preferably, before loading the next sample after cleaning, an inert gas slug or an immiscible isolation liquid slug is introduced, and the corresponding gas phase waste valve or liquid phase waste valve is opened simultaneously to prevent different reagents from coming into contact and mixing in the pipeline.

[0018] Compared with the prior art, the present invention has the following significant advantages: 1. Gas-liquid dual-phase integration, seamless in-situ switching: By integrating gas-phase and liquid-phase observation MEMS chips in series in the front sample stage area, users can switch the electron beam between the gas and liquid observation windows by mechanically moving the electron microscope sample stage without removing the sample rod. This achieves true in-situ observation and comparative study of gas-liquid dual phases, greatly improving experimental efficiency and data consistency.

[0019] 2. Online sample replacement, convenient and efficient operation: Relying on the cooperation of the internal fluid delivery system and the near-end micro-valve control module, the online loading, switching and cleaning of samples are realized, which completely avoids the interference of frequent insertion and removal of sample rods on the electron microscope vacuum system and shortens the experimental cycle.

[0020] 3. Innovative dynamic cleaning mechanism: By injecting cleaning agent through a fluid delivery system and periodically adjusting the pressure of the external pumping system, "pulsating cleaning" of the observation area of ​​the micro-reaction chamber is achieved. This physical cleaning method effectively breaks the laminar flow limitations at the micro-nano scale, powerfully removes dead-angle residues, and significantly reduces the risk of cross-contamination.

[0021] 4. Vacuum and fluid system isolation, high vacuuming efficiency: The vacuuming pipeline and fluid delivery system are physically isolated inside the rod body, effectively avoiding the direct impact of liquid evaporation on the vacuum system, greatly shortening the time required for vacuuming, and improving the overall experimental efficiency.

[0022] 5. Proximal microvalve control for rapid and precise response: The microvalve control module is integrated into the rod body adjacent to the sample stage area, which greatly shortens the pipeline length from the control valve to the reaction zone, reduces the dead volume of the system, and enables millisecond-level rapid switching and precise flow control of gas / liquid samples.

[0023] 6. Multiple safety protection design: The unique front-end vacuum chamber combined with the optional active vacuum shield (vacuum suction) constitutes a two-stage leakage protection mechanism, which can quickly remove the leaked medium in the event of an accidental window breakage, providing effective protection for expensive transmission electron microscope equipment.

[0024] 7. Compact structure and strong compatibility: The overall structure of the sample rod is compact, and the standard interfaces centrally arranged at the handle facilitate sealed connection with external pumping systems. It is easy to integrate into existing transmission electron microscope platforms and is highly practical. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall structure of a sample rod for in-situ observation of gas-liquid two-phase transmission electron microscopy, provided as an embodiment of this application.

[0026] Figure 2 This is an overall cross-sectional view of the sample rod provided in an embodiment of this application.

[0027] Figure 3 A partial cross-sectional view of the sample stage area at the front end of the sample rod and the micro-valve placement chamber provided in the embodiments of this application.

[0028] Figure 4 A partial cross-sectional view of the rear hand grip provided in an embodiment of this application.

[0029] Figure 5 This is an overall cross-sectional view of the sample stage area at the front end of the sample rod provided in an embodiment of this application.

[0030] In the picture: 1-Front-end sample stage area: 11-Gas phase observation MEMS chip, 12-Front-end gas phase outflow pipe, 13-Liquid phase observation MEMS chip, 14-Front-end liquid phase outflow pipe, 15-Front-end vacuum pipe, 16-Front-end liquid phase inflow pipe, 17-Front-end gas phase inflow pipe, 18-Stick head vacuum chamber, 111-First SiN visualization window, 112-Second SiN visualization window; 2-Microvalve control module: 21-Input control valve group, 22-Output control valve group; 3-Shape body: 31-Fluid outflow pipe, 32-Shape body vacuum pipe, 33-Fluid inflow pipe; 4-Handle: 41-Liquid phase outflow port, 42-Gas phase outflow port, 43-Vacuum port, 44-Liquid phase inflow port, 45-Gas phase inflow port, 46-Positioning pin Detailed Implementation

[0031] The present invention will now be described in further detail with reference to the accompanying drawings.

[0032] like Figure 1 As shown, this embodiment provides a gas-liquid two-phase in-situ observation sample rod for transmission electron microscopy. The sample rod is composed of a front sample stage area 1, a microvalve control module 2, a rod body 3, and a handle 4 connected in sequence. It adopts a modular integrated design to solve the problems of traditional in-situ sample rods, such as single function, slow fluid switching, difficulty in in-situ cleaning, and susceptibility of the vacuum system to interference from liquid evaporation.

[0033] like Figure 4As shown, the handle 4 is located at the end of the sample rod. A standard fluid and vacuum interface is provided on the rear face of the handle 4 for easy connection to external pumping systems (such as syringe pumps, mass spectrometers, vacuum pumps, etc.). Specifically, it includes five independent interfaces: a liquid phase outflow interface 41, a gas phase outflow interface 42, a vacuum interface 43, a liquid phase inflow interface 44, and a gas phase inflow interface 45. The vacuum interface 43 is located at the center of the rear face of the handle 4, with the other interfaces arranged around it. Each interface extends beyond the rear face of the handle 4 by a length ≥15 mm to ensure a reliable sealed connection with the external pumping system. The handle 4 internally contains five independent pipes: a rear liquid phase outflow pipe sealed to the liquid phase outflow interface 41, a rear gas phase outflow pipe sealed to the gas phase outflow interface 42, a rear vacuum pipe sealed to the vacuum interface 43, a rear liquid phase inflow pipe sealed to the liquid phase inflow interface 44, and a rear gas phase inflow pipe sealed to the gas phase inflow interface 45. The five tubes gradually converge towards the front end of the handle 4 from the interface. A positioning sheath 46 is provided on the front end of the handle 4 to assist in positioning during the insertion and removal of the sample rod.

[0034] The shaft 3 internally encapsulates three physically isolated transmission channels, including a fluid outflow pipe 31, a shaft vacuum pipe 32, and a fluid inflow pipe 33, such as... Figure 2 As shown. The fluid discharge pipe 31 collects and discharges waste gas / liquid from the front end. Internally, it has separate gas and liquid phase discharge pipes for the handle, with both sealed connections between the gas and liquid phase discharge pipes. The fluid input pipe 33 collects gas and liquid phase inputs from four points on the handle. Internally, it has separate gas and liquid phase inflow pipes for the handle, with both sealed connections between the gas and liquid phase inflow pipes for the handle and the liquid phase inflow pipe for the handle. The vacuum pipe 32 is located on the handle axis and is sealed to the rear vacuum pipe. The vacuum pipe 32 does not share space or couple with any fluid lines. This physical isolation design effectively avoids interference from trace liquid evaporation on vacuum pumping efficiency, ensuring rapid vacuum system establishment and long-term stability.

[0035] The front-end sample stage 1 is the core component of electron beam transmission observation, consisting of an outer casing, such as... Figure 3 and Figure 5As shown, two through holes are arranged side-by-side along the axis of the sample rod inside the outer casing. A chip holder is located at the bottom of each through hole, and microelectromechanical systems (MEMS) chips are arranged on the chip holder. The MEMS chip 11 for gas phase observation is located near the electron beam incident side, while the MEMS chip 13 for liquid phase observation is located behind it. A first SiN visualization window 111 is integrated above the gas phase observation MEMS chip 11, and a second SiN visualization window 112 is integrated below it. Both the first SiN visualization window 111 and the second SiN visualization window 112 are sealed and embedded in the wall of the through hole by a sealing ring. Similarly, SiN visualization windows are also integrated above and below the liquid phase observation MEMS chip 13. The two windows of each chip are precisely aligned vertically. By mechanically shifting the electron microscope sample stage, the transmission area of ​​the electron beam optical axis can be switched, thereby enabling gas-liquid contrast studies in the same or adjacent fields of view.

[0036] In one specific embodiment of the present invention, the through hole can be a tapered light-transmitting hole to ensure that the electron beam can penetrate the gas phase and liquid phase sample regions without obstruction for high-resolution imaging.

[0037] A vacuum chamber 18 is arranged around the two through holes. To achieve independent gas-liquid two-phase transport, the front sample stage area 1 is equipped with multiple microfluidic pipelines, including a front gas phase outflow pipeline 12, a front liquid phase outflow pipeline 14, a front liquid phase inflow pipeline 16, and a front gas phase inflow pipeline 17. Among them, one end of the front gas phase inflow pipeline 17 is connected to the inlet of the micro-reaction chamber of the gas phase observation MEMS chip 11, and the other end passes through the rear end of the vacuum chamber 18 and is sealed to the gas phase inflow pipeline of the rod body, forming a gas phase input pipeline; one end of the front liquid phase inflow pipeline 16 is connected to the inlet of the micro-reaction chamber of the liquid phase observation MEMS chip 13, and the other end passes through the rear end of the vacuum chamber 18 and is sealed to the liquid phase inflow pipeline of the rod body, forming a liquid phase input pipeline; the gas phase input pipeline and the liquid phase input pipeline are used to input liquid or gas into the chip, respectively. One end of the front gas phase outflow pipe 12 is connected to the outlet of the micro-reaction chamber of the gas phase observation MEMS chip 11, and the other end passes through the rear end of the rod head vacuum chamber 18 and is sealed to the rod body gas phase outflow pipe to form a gas phase output pipe; one end of the front liquid phase outflow pipe 14 is connected to the outlet of the micro-reaction chamber of the liquid phase observation MEMS chip 13, and the other end passes through the rear end of the rod head vacuum chamber 18 and is sealed to the rod body liquid phase outflow pipe to form a liquid phase output pipe; the gas phase output pipe and the liquid phase output pipe are used to discharge the waste gas or waste liquid after the reaction from the chip, respectively.

[0038] A front-end vacuum pipe 15 is connected to the center of the rear end of the probe head vacuum chamber 18. The front-end vacuum pipe 15 is sealed to the probe body vacuum pipe 32 to maintain the vacuum level of the probe head vacuum chamber 18, forming an active vacuum shield around the chip: when there is an unexpected gap or insecure seal between the first SiN visualization window 111 or the second SiN visualization window 112 and the sealing ring, the gas or liquid sample in the micro-reaction chamber of the chip is confined within the probe head vacuum chamber 18 and immediately extracted by the vacuum pipe 32, providing effective protection for the expensive transmission electron microscope equipment.

[0039] Furthermore, after each observation, inert gas and cleaning agent can be injected sequentially into the pipeline to remove residual gaseous or liquid samples from the pipeline, dead corners of the microreactor, and the inner wall of the SiN visualization window, preventing any impact on subsequent observations. Inert gases such as nitrogen and argon can be used, while cleaning agents such as acetone, ethanol, and deionized water can be used. This creates a controllable pulsating flow field within the chip's microreactor. The instantaneous shear force and pressure fluctuations generated by this pulsating flow effectively remove stubborn residues and suspend them in the cleaning agent. Subsequently, inert gas is used to blow out the cleaning agent carrying impurities, completing a high-cleanliness cleaning of the pipeline and the chip's microreactor. This achieves thorough removal of residues from dead corners of the microreactor without removing the sample probe and enables efficient, cross-contamination-free continuous sample switching.

[0040] To significantly reduce the dead volume and fluid response delay in the downstream pipeline, this embodiment includes a microvalve control module 2 located within the rod body 3, immediately adjacent to the front sample stage area 1 (approximately 10-20 mm from the front end face of the rod body). Figure 3 As shown, this module integrates an input control valve group 21 and an output control valve group 22. The input control valve group 21 includes a gas phase feed valve and a liquid phase feed valve, used to precisely regulate the timing and flow rate of gas or liquid entering the chip. The gas phase feed valve is connected in series between the gas phase inflow pipe of the rod body and the front gas phase inflow pipe 17, and the liquid phase feed valve is connected in series between the liquid phase inflow pipe of the rod body and the front liquid phase inflow pipe 16. The output control valve group 22 includes a gas phase exhaust valve and a liquid phase exhaust valve, used to prevent waste gas or waste liquid from flowing back or being transferred upwards. The gas phase exhaust valve is connected in series between the gas phase outflow pipe of the rod body and the front gas phase outflow pipe 12, and the liquid phase exhaust valve is connected in series between the liquid phase outflow pipe of the rod body and the front liquid phase outflow pipe 14. Compared with the traditional design that places the valve outside the handle 4, the near-end valve control scheme of this invention shortens the length of the post-valve pipeline to less than centimeters, significantly reducing the dead volume and fluid response delay in the post-valve pipeline, and can achieve millisecond-level fluid switching response.

[0041] By setting up multiple microfluidic pipelines and microvalve control modules, the sample holder in this embodiment can achieve seamless switching between gas phase and liquid phase observation inside the transmission electron microscope without having to remove the sample holder or replace the chip, thus completely avoiding the interference of frequent insertion and removal of the sample holder on the electron microscope vacuum system.

[0042] Based on the aforementioned sample holder for in-situ gas-liquid two-phase observation in transmission electron microscopy, this embodiment also provides a cleaning method for in-situ gas-liquid two-phase observation in transmission electron microscopy, including the following steps: S1. Sample loading and initial vacuuming After the sample rod is inserted into the electron microscope sample stage, the vacuum pump is connected to the vacuum port 43 via an external vacuum pump. The vacuum pumping pipe 32 on the rod body and the vacuum pumping pipe 15 at the front end continuously evacuate the vacuum chamber 18 at the rod head until the preset vacuum level (usually <10 Pa) is reached. Then the micro valve control module 2 is turned on.

[0043] S2, Gas and Liquid Phase Observation Procedure Gas samples are injected into the gas phase inlet 45 via an external injection pump, and liquid samples are injected into the liquid phase inlet 44. Gas samples reach the front end of the rod 3 via the gas phase inlet pipe, and similarly, liquid samples reach the front end of the rod 3 via the liquid phase inlet pipe. Then, under the precise adjustment of the gas phase feed valve and liquid phase feed valve in the input control valve group 21, gas samples enter the micro-reaction chamber of the gas phase observation MEMS chip 11 via the front gas phase inlet pipe 17, and liquid samples enter the micro-reaction chamber of the liquid phase observation MEMS chip 13 via the front liquid phase inlet pipe 16. When the transmission electron microscope is turned on, the electron beam penetrates from top to bottom through the first SiN visualization window 111, the gas phase observation MEMS chip 11, and the second SiN visualization window 112, providing real-time imaging of the dynamic behavior of the sample material in the gas phase environment. By translating the electron microscope sample stage, the electron beam penetrates the liquid phase observation MEMS chip 13 and its corresponding SiN visualization window, providing real-time imaging of the dynamic behavior of the sample material in the liquid phase environment, enabling gas-liquid comparison studies in the same or adjacent fields of view.

[0044] S3, Waste Discharge Driven by the pressure difference generated by the external pump, the observed waste gas and waste liquid flow out of the chip through the front gas phase outlet pipe 12 and the front liquid phase outlet pipe 14 respectively. After reaching the front end of the stick body 3, the waste gas is discharged to the gas phase outlet port 42 of the handle 4 through the gas phase discharge valve in the output control valve group 22 and the stick body gas phase outlet pipe. The waste liquid is discharged to the liquid phase outlet port 41 of the handle 4 through the liquid phase discharge valve in the control valve group 22 and the stick body liquid phase outlet pipe and collected in the external waste gas / waste liquid collection container.

[0045] S4, Routine replacement cleaning After the sample observation is completed, the input control valve group 21 is closed, and an inert gas (nitrogen or argon in this embodiment) is introduced into the gas phase input pipeline and liquid phase input pipeline through the gas phase outflow interface 42 and the liquid phase outflow interface 41 using an external gas source, thereby purging the gas and liquid samples remaining in the pipeline and chip micro-reaction chamber to the waste gas / waste liquid collection container.

[0046] S5, Pulsating Dynamic Cleaning To thoroughly remove dead corners of the micro-reaction chamber and deposits on the inner wall of the SiN visualization window, a cleaning agent (in this embodiment, a solvent such as acetone, ethanol, or deionized water) is injected into the gas phase input pipeline and the liquid phase input pipeline via an external injection pump, filling the micro-reaction chambers of the gas phase observation MEMS chip 11 and the liquid phase observation MEMS chip 13 with the cleaning agent. Then, by periodically adjusting the pressure of the external pumping system, a controllable pulsating flow field is formed in the micro-reaction chamber of the chip by the cleaning agent. The instantaneous shear force and pressure fluctuation generated by the pulsating flow can effectively peel off stubborn residues and suspend them in the cleaning agent. After the pulsating dynamic cleaning lasts for several seconds to several minutes, inert gas is introduced into the gas phase inlet and liquid phase inlet lines again to blow out the cleaning agent carrying impurities.

[0047] The above process can be repeated 2 to 3 times to achieve high-cleanliness regeneration of the chip surface.

[0048] After cleaning, the next set of samples can be directly introduced. To prevent different reagents from mixing in the common pipeline section, an inert gas slug or an immiscible isolation liquid slug can be introduced between the two liquids. Combined with the precise cutoff and auxiliary suction of the microvalve control module 2, zero-mixing sequential observation can be achieved.

[0049] Throughout the process, the vacuum chamber 18 at the probe tip remains under negative pressure. If any gap exists between the SiN visualization window and the sealing ring, or if the seal is not secure, the leaked gas / liquid sample will be confined within the vacuum chamber 18 and quickly removed by the front-end vacuum pipe 15, preventing it from spreading into the high vacuum environment of the electron microscope tube, thus achieving multi-level safety protection with an active vacuum shield.

[0050] Through the above embodiments, the present invention achieves gas-liquid two-phase compatibility, online sample replacement, pulsed in-situ cleaning, and multi-level vacuum safety protection within a single sample rod, significantly improving the efficiency, safety, and data reliability of in-situ transmission electron microscopy experiments.

[0051] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A gas-liquid two-phase in-situ observation sample holder for transmission electron microscopy, characterized in that, It includes a front sample stage area, a rod body, and a handle connected in sequence; The front-end sample stage area includes an outer casing. Inside the outer casing, two through holes are arranged side-by-side along the axis of the sample rod. A gas phase observation MEMS chip and a liquid phase observation MEMS chip are respectively installed in the two through holes. SiN visualization windows are arranged opposite each other on the top and bottom of each chip for observation by transmission electron beam. Slits are provided on the walls of the two through holes, and the SiN visualization windows are sealed and embedded in the slits by sealing rings. A rod head vacuum cavity is provided around the two through holes to form a vacuum shield around the chip. The sample rod is internally equipped with a fluid delivery system and a vacuum pipeline. The fluid delivery system includes at least one gas phase input / output pipeline and one liquid phase input / output pipeline, which are independent of each other from the vacuum pipeline. The gas phase observation MEMS chip is located on the gas phase input / output pipeline, and the liquid phase observation MEMS chip is located on the liquid phase input / output pipeline. The fluid delivery system is connected to an external pumping system and a recovery device to deliver gas phase samples and / or liquid phase samples, respectively or selectively, into the micro-reaction chambers of the gas phase observation MEMS chip and the liquid phase observation MEMS chip, and to discharge waste liquid and waste gas. The axis of the vacuum pipeline coincides with the axis of the sample rod and connects the external vacuum device to the vacuum chamber at the rod head. It is used to maintain the vacuum level of the vacuum chamber at the rod head and to aspirate leaked samples when the seal between the SiN visualization window and the sealing ring fails, preventing contamination of the electron microscope.

2. The sample rod according to claim 1, characterized in that, A micro-valve control module is installed 10-20 mm from the front end of the rod body to control the inflow rate of gas and liquid samples, while preventing the backflow of waste gas and waste liquid. The micro-valve control module includes a gas feed valve, a liquid feed valve, a gas discharge valve, and a liquid discharge valve. The gas feed valve and the gas discharge valve are arranged on the gas input and output pipelines, and the liquid feed valve and the liquid discharge valve are arranged on the liquid input and output pipelines.

3. The sample rod according to claim 1, characterized in that, The gas phase observation MEMS chip is located near the electron beam incident side, and the liquid phase observation MEMS chip is located behind the gas phase observation MEMS chip. By mechanically shifting the electron beam transmission area through the electron microscope sample stage, gas-liquid comparison studies can be achieved in the same or adjacent fields of view.

4. The sample rod according to claim 1, characterized in that, The rear end face of the handle is provided with a fluid interface and a vacuum interface for sealed connection with an external pumping system and recovery device; the fluid interface includes a gas phase inlet interface, a gas phase outlet interface, a liquid phase inlet interface, and a liquid phase outlet interface, the gas phase inlet interface and the gas phase outlet interface are sealed to the gas phase input and output pipelines, and the liquid phase inlet interface and the liquid phase outlet interface are sealed to the liquid phase input and output pipelines; the vacuum interface is sealed to the vacuum pipeline; each interface extends out of the handle by a length of not less than 15mm.

5. The sample rod according to claim 4, characterized in that, The gas phase input and output pipeline includes a gas phase input pipeline and a gas phase output pipeline. One end of the gas phase input pipeline is sealed to the gas phase inflow interface, and the other end is sealed to the micro-reaction chamber of the gas phase observation MEMS chip. One end of the gas phase output pipeline is sealed to the micro-reaction chamber of the gas phase observation MEMS chip, and the other end is sealed to the gas phase outflow interface.

6. The sample rod according to claim 5, characterized in that, The liquid phase input and output pipeline includes a liquid phase input pipeline and a liquid phase output pipeline. One end of the liquid phase input pipeline is sealed to the liquid phase inflow interface, and the other end is sealed to the micro-reaction chamber of the liquid phase observation MEMS chip. One end of the liquid phase output pipeline is sealed to the micro-reaction chamber of the liquid phase observation MEMS chip, and the other end is sealed to the liquid phase outflow interface.

7. The sample rod according to claim 1, characterized in that, The through-hole is a tapered hole to ensure that the electron beam penetrates the gas and liquid phase sample regions without obstruction.

8. An in-situ observation cleaning method for a gas-liquid two-phase in-situ observation sample rod for transmission electron microscopy as described in claim 2, characterized in that, Includes the following steps: S1. After the sample rod is inserted into the electron microscope sample stage, the vacuum chamber of the rod head is continuously evacuated through the vacuum pipeline via an external pumping system until the preset vacuum level is reached. Then the micro valve control module is turned on. S2. Gas phase sample is injected into the gas phase input pipeline through an external pumping system, and liquid phase sample is injected into the liquid phase input pipeline. Under the regulation of the micro valve control module, the gas phase sample enters the micro reaction chamber of the gas phase observation MEMS chip, and the liquid phase sample enters the micro reaction chamber of the liquid phase observation MEMS chip. When the transmission electron microscope is turned on, the electron beam penetrates from top to bottom through the upper SiN visualization window, the gas phase observation MEMS chip, and the lower SiN visualization window to perform real-time imaging of the dynamic behavior of the gas phase sample; the electron microscope sample stage is moved to perform real-time imaging of the dynamic behavior of the liquid phase sample. S3. Under the pressure difference drive, the observed waste gas is discharged through the gas phase output pipeline, and the waste liquid is discharged through the liquid phase output pipeline and collected into the external recovery device. S4. After the sample observation is completed, close the micro-valve control module and introduce inert gas into the fluid delivery system through an external gas source to purge the gas and liquid samples remaining in the pipeline and chip micro-reaction chamber to the external recovery device. S5. Inject cleaning agent into the fluid delivery system through an external pumping system, filling the micro-reaction chambers of the gas phase observation MEMS chip and the liquid phase observation MEMS chip with cleaning agent; by periodically adjusting the pressure of the external pumping system, the cleaning agent generates pulsating motion in the front sample stage area. The instantaneous shear force and pressure fluctuation generated by the pulsating motion shake off and suspend the stubborn residues, which are then discharged from the sample rod with the cleaning agent; after cleaning, inert gas is introduced into the fluid delivery system again to blow out the cleaning agent, and then the next sample loading is performed.

9. The in-situ observation and cleaning method according to claim 8, characterized in that, Before loading the next sample after cleaning, introduce an inert gas slug or an immiscible isolation liquid slug, and simultaneously open the corresponding gas phase waste discharge valve or liquid phase waste discharge valve to prevent different reagents from coming into contact and mixing in the pipeline.

10. The in-situ observation and cleaning method according to claim 8, characterized in that, The cleaning agent is acetone, ethanol, or deionized water.

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