Optical microscopy system for observing droplet phase separation

Abstract

The invention belongs to the technical field of optical microscopy, and particularly discloses an optical microscopy system for observing liquid drop phase separation, which comprises an optical microscope with an objective table, a humidity adjusting unit, a gas tank, a liquid drop phase separation unit, a liquid drop phase separation unit and a liquid drop phase separation unit, an outlet of the gas tank is communicated with an inlet of the first mass flow controller and an inlet of the second mass flow controller, ultrapure water is contained in the gas washing bottle, the heating assembly is arranged on the gas washing bottle, and an outlet of the second mass flow controller is communicated with the gas washing bottle. An outlet of the first mass flow controller and an outlet of the gas washing bottle are communicated with an inlet of the environment cavity, an outlet of the environment cavity is communicated with the atmosphere, and the temperature and humidity detection assembly is arranged in the environment cavity; the control unit is electrically connected with the first mass flow controller, the second mass flow controller and the temperature and humidity detection assembly. According to the invention, the relative humidity in the environment cavity can be continuously changed at a constant rate, so that the phase separation process of sample liquid drops can be observed.

Description

Technical Field

[0001] The invention belongs to the technical field of optical microscopy and relates to an optical microscopy system for observing phase separation of liquid droplets. Background Art

[0002] In the atmospheric environment, changes in relative humidity (RH) can trigger various types of phase transitions in multicomponent particles. The number and composition of phases in the particles will affect atmospheric multiphase and heterogeneous processes. Phase separation and phase mixing are a pair of opposing phase transition processes. Liquid-liquid phase separation refers to the transition from a well-mixed liquid phase to two separate liquid phases, and its threshold is called the separation relative humidity (SRH). Typically, liquid-liquid phase separation results in the formation of particles with a core-shell structure or a partially encapsulated structure. Phase mixing refers to the transition from two separate liquid phases to a well-mixed liquid phase, and its threshold is called the mixing relative humidity (SRH).

[0003] Existing research primarily investigates the phase separation process of atmospheric particulate matter in the field using cryogenic / cryogenic transmission electron microscopy, or Cryo-TEM. Cryo-TEM studies the phase separation process in aerosol samples by placing them in an environmental chamber at fixed humidity levels (e.g., 75% RH, 86% RH, and 95% RH) for 10 minutes. The aerosol samples are then quickly transferred to a container filled with liquid ethane and liquid nitrogen and cooled at approximately 104K to stabilize their morphology.

[0004] However, since the above-mentioned technology requires transferring aerosol samples back and forth, it may ignore certain details of the changes in the existence form or composition of particulate matter during humidity changes. In addition, extremely low temperature conditions may also affect the morphology and composition distribution of aerosol samples, making the research results on the phase separation process of aerosol samples less accurate. Summary of the Invention

[0005] The objective of the present invention is to provide an optical microscope system for observing droplet phase separation, which can achieve continuous changes in the relative humidity in the environmental chamber at a constant rate under stable temperature conditions, thereby enabling detailed observation of the phase separation process of aerosol samples. At the same time, it prevents unstable temperature conditions during the back-and-forth transfer of aerosol samples from affecting the morphology and composition distribution of the aerosol samples, making the research results on the phase separation process of aerosol samples more accurate and reliable.

[0006] To achieve the above objectives, the specific technical solutions provided by the present invention are as follows: An optical microscope system for observing droplet phase separation includes an optical microscope with a stage, an environmental chamber is provided on the stage, and the environmental chamber is used to carry an aerosol sample, and further includes: A humidity control unit, comprising a gas tank, a first mass flow controller, a second mass flow controller, a gas wash bottle, and a heating assembly, wherein the gas tank is used to hold nitrogen gas, the outlet of the gas tank being connected to the inlet of the first mass flow controller and the inlet of the second mass flow controller, respectively; the gas wash bottle is filled with ultrapure water; the heating assembly is disposed on the gas wash bottle and is used to heat the ultrapure water to generate water vapor; the outlet of the second mass flow controller is connected to the gas wash bottle, the outlet of the first mass flow controller and the outlet of the gas wash bottle are respectively connected to the inlet of the environmental chamber, and the outlet of the environmental chamber is connected to the atmosphere; A temperature and humidity detection component is provided inside the environmental cavity and is used to detect temperature and humidity information in the environmental cavity; A control unit is electrically connected to the first mass flow controller, the second mass flow controller and the temperature and humidity detection component, respectively, and is used to adjust the flow rate through the first mass flow controller and the flow rate through the second mass flow controller according to the humidity information in the environmental chamber, so that the relative humidity in the environmental chamber changes at a constant rate.

[0007] Furthermore, the heating assembly includes a heating belt, which is wrapped around the outside of the gas washing bottle and is electrically connected to the control unit.

[0008] Furthermore, the heating component includes a first chiller electrically connected to the control unit. The first chiller has a circulating medium, and the gas washing bottle is placed in the circulating medium to achieve water bath heating.

[0009] Furthermore, the temperature and humidity detection component includes a temperature and humidity sensor, which is arranged at the outlet of the environmental cavity and is used to detect the temperature and humidity in the environmental cavity. The temperature and humidity sensor is electrically connected to the control unit.

[0010] Furthermore, the outlet of the gas tank is detachably connected to the inlet of the splitter, the outlet of the splitter is respectively connected to the inlet of the first mass flow controller and the inlet of the second mass flow controller, the outlet of the first mass flow controller and the outlet of the gas washing bottle are respectively connected to the inlet of the combiner, and the outlet of the combiner is connected to the inlet of the environmental chamber.

[0011] Furthermore, it also includes a first particulate matter filter and a second particulate matter filter for removing particulate matter in the airflow, the inlet of the first particulate matter filter is connected to the outlet of the first mass flow controller, the outlet of the first particulate matter filter is connected to the inlet of the combiner, the inlet of the second particulate matter filter is connected to the outlet of the second mass flow controller, and the outlet of the second particulate matter filter is connected to the inlet of the gas wash bottle.

[0012] Furthermore, the environmental chamber includes a shell and a sample stage arranged in the shell, and a temperature adjustment unit is provided on the sample stage for adjusting the temperature of the environmental chamber according to a preset target temperature. The sample stage includes a first metal plate, an interlayer and a second metal plate arranged in sequence from top to bottom, wherein the first metal plate is used to carry the sample, and the second metal plate is fixed to the shell.

[0013] Furthermore, the temperature regulating unit includes a Peltier semiconductor chip, which is arranged in the interlayer, and the Peltier semiconductor chip and the temperature and humidity detection component are electrically connected to the control unit respectively.

[0014] Furthermore, a circulating medium for liquid cooling is provided in the interlayer, and the interlayer is respectively connected to a water inlet pipe and a water outlet pipe of a second chiller, and the second chiller is used to realize the flow of the circulating medium.

[0015] Compared with the prior art, the optical microscope system for observing droplet phase separation of the present invention uses an environmental chamber to carry aerosol samples, and is simultaneously equipped with a humidity adjustment unit and a temperature and humidity detection component. The humidity adjustment unit can be controlled based on the monitoring information of the temperature and humidity detection component, and the relative humidity in the environmental chamber can be continuously changed at a constant rate under stable temperature conditions, thereby enabling detailed observation of the phase separation process of the aerosol sample. At the same time, it prevents the unstable temperature conditions during the back-and-forth transfer of the aerosol sample from affecting the morphology and composition distribution of the aerosol sample, making the research results on the phase separation process of the aerosol sample more accurate and reliable, highly practical, and worthy of promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0017] Figure 2 Schematic diagram of the environmental chamber of the present invention.

[0018] Reference numerals: 1. Gas tank, 2. Splitter, 3. First mass flow controller, 4. Second mass flow controller, 5. First particulate filter, 6. Second particulate filter, 7. Gas washing bottle, 8. Combiner, 9. Second chiller, 10. CCD camera, 11. Eyepiece, 12. Environmental chamber, 13. Temperature and humidity sensor, 14. Stage, 15. Light source. DETAILED DESCRIPTION

[0019] The main research method for the phase separation process of atmospheric particles in the actual field is low-temperature / cryo-transmission electron microscopy. The research on the phase separation process of aerosol samples is carried out by placing the aerosol samples in an environmental chamber under certain fixed humidity conditions to absorb moisture for 10 minutes. For example, the aerosol samples are placed in environmental chambers with 75% RH, 86% RH, and 95% RH. The aerosol samples are then quickly transferred to a container filled with liquid ethane and liquid nitrogen, and cooled at a temperature of about 104K to fix their shape.

[0020] However, since the above-mentioned technology requires transferring aerosol samples back and forth, it may ignore certain details of the changes in the existence form or composition of particulate matter during humidity changes. In addition, extremely low temperature conditions may also affect the morphology and composition distribution of aerosol samples, making the research results on the phase separation process of aerosol samples less accurate.

[0021] In order to solve the above technical problems, the present application provides an optical microscope system for observing droplet phase separation.

[0022] In order to enable those skilled in the art to better understand the technical solution of the present invention and implement it, Figure 1 and Figure 2 , clearly and comprehensively describe the technical solutions in the present invention.

[0023] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0024] In addition, it should be further explained that in the description of the embodiments of the present invention, unless otherwise specified, " / " means or, for example, A / B can mean A or B: "and / or" in the text is merely a way to describe the association relationship of associated objects, indicating that three relationships can exist, for example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone.

[0025] The terms "first," "second," "third," and "fourth" below are used for descriptive purposes only and should not be understood to imply or suggest relative importance or implicitly indicate the number of the technical features indicated. Thus, features qualified as "first," "second," "third," and "fourth" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0026] Example 1 In order to realize the observation of the phase separation process of the aerosol sample and the accurate measurement of the separation relative humidity SRH, the present invention independently builds an optical microscope system for observing the phase separation of droplets coupled to an environmental chamber 12 with temperature and humidity control functions.

[0027] The present invention uses an optical method to measure the liquid-liquid phase separation of droplets, and the measurement principle is as follows: During phase transitions, particle morphology and species distribution change, and different species exhibit distinct light absorption and reflection properties. When phase separation occurs, the boundary between organic and inorganic compounds in optical images can be used to identify the onset of phase separation. Therefore, optical microscopy can be used to determine the relative humidity of separation and the specific mechanism of liquid-liquid phase separation.

[0028] The schematic diagram of the present invention and the schematic diagram of the local structure are respectively as follows Figure 1 and Figure 2 The specific instructions are as follows: 1. Humidity Control Unit like Figure 1 As shown, the humidity control unit primarily consists of a gas tank 1, a first mass flow controller 3, a second mass flow controller 4, a first particulate filter 5, a second particulate filter 6, and a porous glass gas wash bottle 7 filled with ultrapure water. The gas tank 1 holds high-purity nitrogen. Gas wash bottle 7 is equipped with a heating assembly that heats the ultrapure water to produce water vapor. When dry nitrogen passes through gas wash bottle 7, it mixes with the generated water vapor, producing humidified gas.

[0029] Specifically, the heating assembly includes a heating belt, which is wound around the outside of the gas washing bottle 7 and is electrically connected to the control unit. The heating belt heats the ultrapure water in the gas washing bottle 7 to generate water vapor.

[0030] As an alternative to the above-mentioned scheme, the heating component includes a first chiller electrically connected to the control unit, the first chiller has a circulating medium, the gas washing bottle 7 is placed in the circulating medium of the first chiller, and the temperature of the circulating medium in the first chiller is adjusted. The circulating medium can be water, antifreeze or ethanol, and the ultrapure water in the gas washing bottle 7 is heated in a water bath to generate water vapor.

[0031] Specifically, the mass flow controller is referred to as MFC, and the first mass flow controller 3 and the second mass flow controller 4 are 0-2 SLPM from Alicat Company of the United States.

[0032] Specifically, the particulate filter is referred to as HEPA, and the first particulate filter 5 and the second particulate filter 6 are 02FA06A from Parker Company of the United States.

[0033] During operation, the humidity control unit is connected to a gas tank 1, which contains 40L of high-purity nitrogen N2 from North Vancouver Gas Company. The purity of the nitrogen N2 is 99.999%. After entering the system, the high-purity nitrogen N2 is divided into two paths by a splitter 2. One path is a dry gas path that passes only through a first mass flow controller 3 and a first particulate filter 5, while the other path passes through a second mass flow controller 4, a second particulate filter 6, and a gas wash bottle 7 filled with ultrapure water to produce humidified gas. The two gas paths are then combined through a combiner 8 and passed into the environmental chamber 12 from the air inlet on the left side of the environmental chamber 12 through a perfluoroalkoxy resin (PFA) tube. The first and second mass flow controllers 3 and 4 can also be controlled by a Labview program. Through PID feedback regulation, the ratio of the dry and wet gas flows is adjusted to ensure that the mixed gas reaches the target relative humidity. After adjustment in the above manner, the environmental chamber 12 of the present invention can achieve a relative humidity range of 0 to 96%.

[0034] 2. Optical Microscope The optical microscope system mainly includes a CCD camera 10 , an eyepiece 11 , a stage 14 , and an LED light source 15 located below the stage 14 .

[0035] The CCD camera 10 is used to display and record images, and its model is DMK33G274 produced by German ImagingSource Company.

[0036] The optional magnifications of the eyepiece 11 are 10 times, 20 times and 50 times.

[0037] 3. Environmental Chamber 12 The schematic diagram of the environmental chamber 12 with temperature and relative humidity control function is shown in FIG. Figure 2 As shown. Inside the environmental chamber 12, there is a temperature and humidity detection component for detecting the temperature and humidity information in the environmental chamber 12. Here, the temperature and humidity detection component adopts a temperature and humidity sensor 13, which is arranged at the exit of the environmental chamber 12 and is used to detect the temperature and humidity in the environmental chamber 12. The temperature and humidity sensor 13 is electrically connected to the control unit.

[0038] The target humidity airflow generated by the humidity control unit enters the environment chamber 12 through the left inlet of the environment chamber 12 and fills the environment chamber 12. The remaining gas flows out from the right outlet of the environment chamber 12 and is measured by the temperature and humidity sensor 13 placed at the outlet.

[0039] Specifically, the model of the temperature and humidity sensor 13 is SHT45-AD1B produced by Sensirion of Switzerland, and the temperature and relative humidity uncertainties of the sensor are ±0.1° C. and ±1.0% respectively.

[0040] The temperature control principle within environmental chamber 12 is based on the Peltier effect. Specifically, environmental chamber 12 includes a housing and a sample stage disposed within the housing. The sample stage is a multi-layer structure comprising, from top to bottom, a first metal plate, a spacer, and a second metal plate. The first metal plate is used to support the sample and transfer heat, while the second metal plate is fixed to the housing.

[0041] The Peltier semiconductor chip is housed within the interlayer and electrically connected to an external control unit. When temperature control is required, an electrical signal is supplied to the chip via the external control unit. Due to the Peltier effect, when current flows through a loop composed of different conductors, in addition to generating irreversible Joule heating, heat absorption and release occur at the junctions of the different conductors, depending on the direction of the current flow. This, in turn, controls the temperature of the Peltier semiconductor chip.

[0042] A circulating medium is also provided in the interlayer, and the interlayer is connected to the water inlet pipe and the water outlet pipe of the second chiller 9 respectively. When the Peltier semiconductor chip is working, the second chiller 9 works synchronously. The liquid in the second chiller 9 is generally antifreeze or ethanol, and its built-in pump drives the liquid to circulate under the Peltier semiconductor chip. The liquid medium circulates to take away heat, achieving a cooling effect, so that the temperature of the environmental chamber 12 reaches a wide temperature range from room temperature to -40°C.

[0043] All the above-mentioned electronic control components are electrically connected to the control unit, and the control unit can realize automatic control by combining software and hardware. Among them, the control of the hardware part can be realized by PID method.

[0044] 4. Labview control program Software control is achieved using a customized Labview control program. The total airflow rate can be controlled within the range of 0-2 SLPM, and relative humidity can be controlled and temperature and humidity data can be recorded in three modes.

[0045] The first mode is the Manual Set Mode, where any relative humidity value between 0 and 100% RH can be set. Subsequently, the first and second mass flow controllers 3 and 4 use PID feedback to adjust the dry and wet gas ratios, quickly achieving the set target relative humidity and achieving precise control of the relative humidity within the environmental chamber 12.

[0046] The second mode is Auto Fall Mode. In this mode, you can set an initial relative humidity value and a fixed relative humidity change rate. Once the set target initial relative humidity value is reached, the relative humidity continues to decrease from the initial setting value to near 0% RH at this constant rate.

[0047] The third mode is Auto Rise Mode. In this mode, you can set an initial relative humidity value and a fixed relative humidity change rate. Once the set initial relative humidity is reached, the relative humidity gradually increases from the initial set value to nearly 100% RH at this constant rate.

[0048] In general, the technical solution of the present invention has the following beneficial effects compared with the prior art: The optical microscope system for observing droplet phase separation provided by the present invention utilizes an environmental chamber to carry aerosol samples, and is simultaneously provided with a humidity adjustment unit and a temperature and humidity detection component. The humidity adjustment unit can be controlled based on the monitoring information of the temperature and humidity detection component, and the relative humidity in the environmental chamber can be continuously changed at a constant rate under stable temperature conditions, thereby enabling detailed observation of the phase separation process of the aerosol sample. At the same time, the possible influence of unstable temperature conditions on the morphology and composition distribution of the aerosol sample during the back-and-forth transfer of the aerosol sample is prevented, thereby making the research results on the phase separation process of the aerosol sample more accurate and reliable, highly practical, and worthy of promotion.

[0049] It will be understood that the present invention is described through some embodiments, and those skilled in the art will appreciate that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention.

[0050] Furthermore, these features and embodiments may be modified to suit specific circumstances and materials under the teachings of the present invention without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of the present invention are intended to be protected by the present invention.

Claims

1. An optical microscope system for observing phase separation of droplets, characterized in that: The invention comprises an optical microscope having a stage (14), wherein an environmental cavity (12) is provided on the stage (14), and the environmental cavity (12) is used to carry an aerosol sample, and further comprises: A humidity regulating unit comprises a gas tank (1), a first mass flow controller (3), a second mass flow controller (4), a gas washing bottle (7) and a heating component, wherein the gas tank (1) is used to contain nitrogen gas, the outlet of the gas tank (1) is respectively connected to the inlet of the first mass flow controller (3) and the inlet of the second mass flow controller (4), the gas washing bottle (7) contains ultrapure water, the heating component is arranged on the gas washing bottle (7) and is used to heat the ultrapure water to generate water vapor, the outlet of the second mass flow controller (4) is connected to the gas washing bottle (7), the outlet of the first mass flow controller (3) and the outlet of the gas washing bottle (7) are respectively connected to the inlet of the environmental chamber (12), and the outlet of the environmental chamber (12) is connected to the atmosphere; A temperature and humidity detection component, arranged inside the environmental cavity (12), and used to detect temperature and humidity information inside the environmental cavity (12); A control unit is electrically connected to the first mass flow controller (3), the second mass flow controller (4) and the temperature and humidity detection component, respectively, and is used to adjust the flow rate through the first mass flow controller (3) and the flow rate through the second mass flow controller (4) according to the humidity information in the environmental chamber (12), so as to achieve a change in the relative humidity in the environmental chamber (12) at a constant rate.

2. The optical microscope system for observing droplet phase separation according to claim 1, characterized in that: The heating assembly comprises a heating belt, the heating belt is wound around the outside of the gas washing bottle (7), and the heating belt is electrically connected to a control unit.

3. The optical microscope system for observing droplet phase separation according to claim 1, characterized in that: The heating component comprises a first water chiller electrically connected to the control unit, wherein the first water chiller has a circulating medium, and the gas washing bottle (7) is placed in the circulating medium for achieving water bath heating.

4. The optical microscope system for observing droplet phase separation according to any one of claims 2 or 3, characterized in that: The temperature and humidity detection component comprises a temperature and humidity sensor (13), which is arranged at the outlet of the environmental cavity (12) and is used to detect the temperature and humidity in the environmental cavity (12); the temperature and humidity sensor (13) is electrically connected to a control unit.

5. The optical microscope system for observing droplet phase separation according to claim 4, characterized in that: The outlet of the gas tank (1) is detachably connected to the inlet of the splitter (2), the outlet of the splitter (2) is respectively connected to the inlet of the first mass flow controller (3) and the inlet of the second mass flow controller (4), the outlet of the first mass flow controller (3) and the outlet of the gas washing bottle (7) are respectively connected to the inlet of the combiner (8), and the outlet of the combiner (8) is connected to the inlet of the environmental chamber (12).

6. The optical microscope system for observing droplet phase separation according to claim 5, characterized in that: The system further comprises a first particulate filter (5) and a second particulate filter (6) for removing particulate matter, wherein the inlet of the first particulate filter (5) is connected to the outlet of the first mass flow controller (3), the outlet of the first particulate filter (5) is communicated with the inlet of the combiner (8), the inlet of the second particulate filter (6) is connected to the outlet of the second mass flow controller (4), and the outlet of the second particulate filter (6) is communicated with the inlet of the gas wash bottle (7).

7. The optical microscope system for observing droplet phase separation according to claim 4, characterized in that: The environmental chamber (12) comprises a shell and a sample stage arranged in the shell, wherein a temperature regulating unit is arranged on the sample stage for regulating the temperature of the environmental chamber (12) according to a preset target temperature, and wherein the sample stage comprises a first metal plate, a partition layer, and a second metal plate arranged in sequence from top to bottom, wherein the first metal plate is used to carry the sample, and the second metal plate is fixed to the shell.

8. The optical microscope system for observing droplet phase separation according to claim 7, characterized in that: The temperature regulating unit includes a Peltier semiconductor chip, which is arranged in the interlayer. The Peltier semiconductor chip and the temperature and humidity detection component are electrically connected to the control unit respectively.

9. The optical microscope system for observing droplet phase separation according to claim 8, characterized in that: A circulating medium for achieving liquid cooling is provided in the interlayer, and the interlayer is respectively connected to the water inlet pipe and the water outlet pipe of the second chiller (9), and the second chiller (9) is used to achieve the flow of the circulating medium.

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