Micro / nano bubble monitoring system and method based on electric signals

Abstract

The invention discloses a micro / nano bubble monitoring system based on an electric signal. The micro / nano bubble monitoring system comprises a detection table, a base plate, a collecting lens, a current detection device and a computer, a micro-channel is arranged on the base plate, and a photothermal conversion layer is arranged on the surface of the micro-channel; the main body of the detection table is a liquid storage tank for storing working fluid, the base plate is obliquely fixed in the liquid storage tank, and the working fluid enters the micro-channel from the bottom end of the micro-channel; the collecting lens is arranged obliquely above the substrate plate and used for collecting external light into a light beam to irradiate the light beam on the photothermal conversion layer of the micro-channel, and the external light is light capable of exciting a photothermal conversion layer material to convert light energy into heat energy; a first electrode is arranged at the top end of the microchannel, a second electrode is arranged at the bottom end of the microchannel, and the first electrode and the second electrode are connected with the current detection device through wires respectively; the current detection device is connected with the computer through a data line.

Description

Technical Field

[0001] The present invention relates to the technical field of micro / nano bubble monitoring, and in particular to a micro / nano bubble monitoring system and method based on electrical signals. Background Art

[0002] Interfacial evaporation uses photothermal materials to convert light energy into heat energy, and confines the heat energy to the evaporation interface to produce steam, which is then condensed to obtain clean water, providing a simple way to treat and produce clean water in remote areas off the grid. Using photothermal conversion technology to increase the evaporation rate of working fluids is currently a hot topic in the research of solar interfacial evaporation. During the photothermal conversion process, when the light intensity irradiating the evaporation surface is large enough, we can observe the generation of larger bubbles. However, when the concentrated solar intensity is low, although the photothermal material will provide nucleation sites for the generation of micro / nano bubbles, the fluid has not reached the boiling point, and the generation of micro / nano bubbles is almost impossible. Under such conditions, the possible reason for the formation of micro / nano bubbles is that the uneven distribution of temperature and solar radiation leads to local boiling in the overheated area, that is, microscale boiling. Current research has shown that the evaporation rate of interfacial evaporation will exceed its theoretical value of 1.47kg / m -2 h -1 Therefore, we need to clarify the reasons for the abnormal increase in evaporation rate so as to regulate the size of the evaporation rate. The abnormal increase in evaporation rate may be related to microscale boiling. Furthermore, we need to observe the bubble nucleation and growth evolution process on the nano-surface of the photothermal material and measure the contribution of the microscale boiling process to the evaporation rate. During the microscale boiling process, as heat accumulates, micro / nano bubbles gradually increase and gather into larger bubbles. At this time, the generation of larger bubbles can be observed; however, there is currently no more effective method to monitor the initial stage of bubble generation, that is, when the bubble size is still at the micro / nano level.

[0003] Existing micro / nano bubble monitoring technologies typically include bubble visualization and optical signal bubble monitoring. For example, Chinese invention patent application publication number CN 119712037A discloses an experimental device and method for simulating CO2 micro / nano bubble recovery and monitoring storage. This device utilizes high-intensity X-ray computed tomography (X-CT) technology to monitor the storage effect of CO2 micro / nano bubbles in reservoirs in real time. The specific principle is as follows: the generated CO2 micro / nano bubble dispersed phase flows through a six-way valve into a micro / nano bubble phase visualization device. An image capture camera is activated to record the phase changes of the micro / nano bubbles. Next, the flow control valve is closed, and the CO2 micro / nano bubble dispersed phase is injected into a core holder for oil displacement. A high-intensity X-ray computed tomography (X-CT) scanner records and analyzes the process of CO2 micro / nano bubble displacement of the oil sample. The high-intensity X-ray computed tomography (X-CT) scanner scans and images the core, and a master control system monitors the changes and diffusion of the CO2 micro / nano bubbles trapped within the core, generating real-time images.

[0004] Among existing technologies, "visualization" of the behavior of micro / nanobubbles is a relatively common method. However, visualization equipment is usually complex and has high maintenance costs. On the other hand, the current generation of micro / nanobubbles is achieved by heating the fluid with an external heat source, which consumes a lot of energy and has an unstable energy supply. In other words, for the monitoring process of micro / nanobubbles, there are currently some real-time monitoring methods and detailed guidance. Most of them use relatively bulky and complex instruments or systems, such as scanning electron microscopes and atomic force microscopes, and most of them work on the principle of converting optical signals or other non-electrical signals into electrical signals. A monitoring system with a simple structure, low cost, and accurate and reliable detection results is needed. Summary of the Invention

[0005] The purpose of the present invention is to address the above problems and provide a micro / nano bubble monitoring system and method based on electrical signals.

[0006] In order to achieve its purpose, the present invention adopts the following technical solutions:

[0007] A first aspect of the present invention provides a micro / nano bubble monitoring system based on electrical signals, comprising a detection platform (1), a base plate (2), a condenser lens (3), a current detection device (4) and a computer (5);

[0008] A microchannel (21) is provided on the base plate (2), and a light-to-heat conversion layer (21a) is provided on the surface of the microchannel (21), so that external light can pass through the microchannel (21) and reach the light-to-heat conversion layer (21a);

[0009] The main body of the detection platform (1) is a liquid reservoir (11) for storing a working fluid, the base plate (2) is fixed in the liquid reservoir (11) at an angle, the bottom of the base plate (2) is immersed in the working fluid in the liquid reservoir (11), the working fluid enters the microchannel (21) from the bottom end of the microchannel (21), and the top end of the microchannel (21) is connected to the atmosphere to discharge bubbles;

[0010] The condenser (3) is arranged obliquely above the base plate (2) and collects external light into a light beam that irradiates the light-heat conversion layer (21a) of the microchannel (21), wherein the external light is light that can excite the material of the light-heat conversion layer (21a) to convert light energy into heat energy;

[0011] A first electrode (41) is provided at the top end of the microchannel (21), and a second electrode (42) is provided at the bottom end of the microchannel (21). The first electrode (41) and the second electrode (42) are respectively connected to a current detection device (4) via a wire (43); and the current detection device (4) is connected to the computer (5) via a data line.

[0012] Preferably, the electrical signal-based micro / nano bubble monitoring system of the present invention further comprises a light source generator (6) for providing a light source, wherein the light source generator (6) is preferably a sunlight simulation device, and the sunlight simulation device is preferably a xenon lamp.

[0013] Preferably, the micro / nano bubble monitoring system based on electrical signals of the present invention further comprises a bubble visualization observation device (7), and the bubble visualization observation device (7) is a scanning electron microscope, an atomic force microscope or a high-speed camera.

[0014] Preferably, the top and bottom ends of the microchannel (21) are provided with electrode mounting holes for mounting electrodes;

[0015] The angle between the base plate (2) and the bottom plate of the detection platform (1) is 30° to 90°, preferably 40° to 60°; the angle between the light beam of external illumination focused by the condenser (3) and the base plate (2) is 45° to 90°.

[0016] The microchannel (21) of the base plate (2) can be realized in either of the following two ways:

[0017] The first type is characterized in that a groove (22) is provided on the upper surface of the base plate (2), and a light-heat conversion layer (21a) is provided on the surface of the groove (22); a transparent cover plate (23) is provided on the base plate (2), which is used to cover the upper surface of the base plate (2) to form the microchannel (21) between the groove (22) and the transparent cover plate (23); the bottom end of the microchannel (21) is in contact with the working fluid in the liquid reservoir (11), and the top end is connected to the atmosphere; the material of the base plate (2) is a non-conductive material that is resistant to heat emitted by the light source, preferably polydimethylsiloxane (PDMS) or quartz glass.

[0018] Preferably, the transparent cover sheet (23) is a glass cover sheet; the groove (22) has a width of 50 to 500 μm, a depth of 70 to 700 μm, and a length of 10 to 60 mm.

[0019] The second type is that the base plate (2) is made of a transparent material and has the microchannel (21) opened inside. Both ends of the microchannel (21) reach the edge of the base plate (2). The base plate (2) is made of a light-transmitting material that is non-conductive and resistant to heat from a light source, preferably quartz glass. The width of the microchannel (21) is 50 to 500 μm, the depth is 70 to 700 μm, and the length is 10 to 60 mm.

[0020] Preferably, the condenser (3) is a convex lens;

[0021] The light-to-heat conversion layer (21a) is a nanosilver particle layer, a polypyrrole or a carbon nanotube coating;

[0022] The current detection device (4) is an electrochemical workstation or a current acquisition card; the first electrode (41) and the second electrode (42) are both copper electrodes; and the working fluid in the microchannel (21) is a low-boiling-point fluid, preferably water or seawater.

[0023] Preferably, the micro / nano bubble monitoring system based on electrical signals of the present invention further comprises an anti-vibration platform (8), wherein the detection platform (1) is arranged on the anti-vibration platform (8) to reduce or eliminate the influence of device shaking on the detection results; and a light shielding plate (24) is further arranged on the base plate (2), wherein the light shielding plate (24) covers the portion of the upper part of the microchannel (21) that is not focused by the light spot.

[0024] A second aspect of the present invention provides a method for monitoring micro / nano bubbles, which is performed using any of the monitoring systems described above, comprising the following steps:

[0025] A working fluid is added to a liquid reservoir (11), external light is directed toward a condenser lens (3), a current detection device (4) and a computer (5) are turned on, and changes in the current in the microchannel (21) are recorded, thereby monitoring the generation of micro / nano bubbles in the microchannel (21).

[0026] The beneficial effects of the present invention are: it cleverly combines the solar interface evaporation system, microchannels, and electrical signal detection together to achieve the innovative use of electrical signals to monitor the growth process of micro / nano bubbles. The present invention introduces a solar interface evaporation system, uses photothermal materials to generate bubbles, collects electrical signals in the microchannel, and judges the growth process of micro / nano bubbles in the microchannel by analyzing the electrical signals; uses electrical signal changes to indirectly monitor micro / nano bubbles, with low equipment cost and simple operation; at the same time, combined with solar interface evaporation, light energy is converted into heat energy, continuously providing energy for the generation of micro / nano bubbles. Compared with other monitoring systems in the prior art that require large or expensive instruments, the system of the present invention has a simple structure, low cost, convenient and quick operation, and good monitoring stability. Experimental verification shows that the system of the present invention monitors the generation and growth of micro / nano bubbles through current changes, and the results are accurate and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural diagram of the monitoring system of the present invention.

[0028] Figure 2 yes Figure 1 Schematic diagram of the structure of the base plate.

[0029] Figure 3 This is a top view of the base plate in 1.

[0030] Figure 4 This is a physical picture of the monitoring system of the present invention constructed in Example 3.

[0031] Figure 5 This is the change of microchannel current over time during the illumination period of 4740s-4790s in Example 3.

[0032] Figure 6 This is the comparison inside the microchannel before and after illumination of the microchannel.

[0033] Figure 7 It is the current change trend within 0-5000s of illumination.

[0034] Among them, Figure 1-3 The elements or structures indicated by the symbols are:

[0035] Detection platform 1, liquid reservoir 11, base plate 2, microchannel 21, photothermal conversion layer 21a, groove 22, transparent cover 23, shading plate 24, condenser 3, current detection device 4, first electrode 41, second electrode 42, wire 43, computer 5, light source generator 6, bubble visualization observation device 7, anti-vibration platform 8. DETAILED DESCRIPTION

[0036] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention, but the present invention is not limited thereby. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0037] The experimental methods in the following examples are conventional methods unless otherwise specified.

[0038] like Figure 1-3The present invention is a micro / nano bubble monitoring system based on electrical signals, which is mainly composed of a detection platform 1, a base plate 2, a condenser 3, a current detection device 4 and a computer 5; a microchannel 21 is provided on the base plate 2, and a light-heat conversion layer 21a is provided on the surface of the microchannel 21, and external light can pass through the microchannel 21 to reach the light-heat conversion layer 21a; the main body of the detection platform 1 is a liquid reservoir 11 for storing a working fluid, the base plate 2 is fixed at an angle in the liquid reservoir 11, and the bottom of the base plate 2 is immersed in the working fluid in the liquid reservoir 11, and the working fluid enters from the bottom end of the microchannel 21. The microchannel 21 is provided with a first electrode 41 at the top and a second electrode 42 at the bottom, and the first electrode 41 and the second electrode 42 are connected to the current detection device 4 through a wire 43 respectively; the current detection device 4 is connected to the computer 5 through a data line.

[0039] In some embodiments, the electrical signal-based micro / nanobubble monitoring system of the present invention further includes a light source generator 6 for providing a light source. Light source generator 6 is preferably a sunlight simulator, preferably a xenon lamp. The monitoring system of the present invention can be used for experiments outdoors under natural sunlight or indoors. Indoor experiments require the use of light source generator 6 to generate simulated sunlight to illuminate concentrator 3.

[0040] In some embodiments, the electrical signal-based micro / nano bubble monitoring system of the present invention further includes a bubble visualization device 7, which can be a scanning electron microscope, an atomic force microscope, or a high-speed camera. Experiments have confirmed that the current signal changes in the monitoring system of the present invention accurately reflect the generation of micro / nano bubbles. Using the bubble visualization device 7, the correlation between current changes and the actual generation of micro / nano bubbles can be further verified.

[0041] In some embodiments, electrode mounting holes for mounting electrodes are provided at the top and bottom ends of the microchannel 21. Since both ends of the microchannel are at the micron level, the holes at both ends can be enlarged to have enough space to accommodate the electrodes, and microelectrodes can also be used.

[0042] In some embodiments, the angle between the base plate 2 and the bottom plate of the detection platform 1 is 30° to 90°, preferably 40° to 60°, and more preferably 45°; the angle between the light beam after the external light is focused by the condenser 3 and the base plate 2 is 45° to 90°, and the light beam is preferably irradiated vertically onto the microchannel 21 on the base plate 2 to improve the efficiency of light energy utilization.

[0043] There are two ways to implement the microchannel 21, either of which can be used. One is as follows:

[0044] The upper surface of the base plate 2 is provided with a groove 22, on which a light-to-heat conversion layer 21a is disposed. A transparent cover sheet 23 is provided on the base plate 2, covering the upper surface of the base plate 2 to form a microchannel 21 between the groove 22 and the transparent cover sheet 23. The bottom end of the microchannel 21 contacts the working fluid in the liquid reservoir 11, and the top end is connected to the atmosphere. The base plate 2 is made of a non-conductive material that is resistant to heat from the light source, preferably polydimethylsiloxane (PDMS) or quartz glass. Preferably, the transparent cover sheet 23 is a glass cover sheet. The groove 22 has a width of 50-500 μm, a depth of 70-700 μm, and a length of 10-60 mm.

[0045] Another implementation of the microchannel 21 is:

[0046] The base plate 2 is made of a transparent material and has a microchannel 21 formed therein. Both ends of the microchannel 21 reach the edges of the base plate 2. The base plate 2 is made of a light-transmitting material that is non-conductive and resistant to heat from the light source, preferably quartz glass. The microchannel 21 has a width of 50 to 500 μm, a depth of 70 to 700 μm, and a length of 10 to 60 mm.

[0047] In some embodiments, the focusing mirror 3 is a convex lens; the photothermal conversion layer 21a is a nanosilver particle layer, a polypyrrole or a carbon nanotube coating; the current detection device 4 is an electrochemical workstation or a current acquisition card, and the first electrode 41 and the second electrode 42 are both copper electrodes; the working fluid in the microchannel 21 is a low-boiling-point fluid, preferably water or seawater.

[0048] In some embodiments, the electrical signal-based micro / nano bubble monitoring system of the present invention further includes an anti-vibration platform 8 , and the detection platform 1 is disposed on the anti-vibration platform 8 to reduce or eliminate the influence of device shaking on the detection results.

[0049] In some embodiments, a light shielding plate 24 is further provided on the base plate 2, and the light shielding plate 24 covers the upper portion of the microchannel 21 that is not focused by the light spot; since the change in the position of the light source will cause the position of the light spot to change, the light intensity received by the area outside the light spot focus area is different from that of the light spot focus area. In order to accurately study the generation of micro / nano bubbles by photothermal conversion, a light shielding plate 24 can be provided to avoid the influence of the light intensity received by other areas being different from that of the light spot focus area on the accuracy of the results.

[0050] The working principle of the monitoring system of the present invention is as follows:

[0051] (1) The monitoring system of the present invention is constructed by combining photothermal conversion technology and Ohm's law. A working fluid is introduced into a microchannel with photothermal material deposited on the surface. When conducting experiments indoors, a light source simulating sunlight of a certain intensity is set up above the base plate, and a light spot of a certain size is formed by focusing through a concentrator to irradiate the photothermal material in the microchannel. When the photothermal material is exposed to light, a photothermal conversion process occurs, and the energy is absorbed to increase the temperature inside the microchannel. Because the photothermal material provides many nucleation sites, during the temperature rise process, some local hot spots appear on the surface of the microchannel where tiny bubbles first grow, and gradually grow with continued light exposure. Since electrodes are connected to both ends of the microchannel, when the microchannel is filled with working fluid, a loop is formed with the current detection device, and the electrical signal data is collected by the current detection device and uploaded to the computer, and the subtle changes in the current in the loop are displayed in real time.

[0052] (2) According to Ohm's law, due to the fixed applied voltage in the microchannel, the resistance increases, resulting in a decrease in the current in the channel. When the bubbles in the microchannel are large enough, a large enough cavity is formed in the microchannel, which blocks the microchannel current path, thereby increasing the resistance of the entire microchannel and changing the path current. In this process, there is a certain relationship between the size of the cavity caused by the bubble and the microchannel resistance. The resulting change in current can represent the growth process of micro / nano bubbles. The top of the microchannel is connected to the atmosphere, and the bubbles will eventually be discharged.

[0053] (3) During the entire process, in order to eliminate the resistance change that may be caused by the decrease in the liquid level due to evaporation, a liquid reservoir is connected outside the microchannel to maintain the liquid level. The liquid reservoir contains the working fluid, and the principle of liquid replenishment is to draw the working fluid from the reservoir into the microchannel through the capillary force inside the microchannel.

[0054] Example 2

[0055] A method for monitoring micro / nano bubbles of the present invention is performed using the monitoring system of Example 1. The operating steps are as follows: adding a working fluid to a liquid reservoir 11, aligning external light with a condenser 3, turning on a current detection device 4 and a computer 5, recording changes in the current in a microchannel 21, and thereby monitoring the generation of micro / nano bubbles in the microchannel 21.

[0056] Example 3

[0057] Build the monitoring system of Example 1 (the physical object is as follows Figure 4As shown), the photothermal conversion layer on the surface of the microchannel is obtained by nanosilver deposition, the sunlight simulation device uses a xenon lamp, and the current detection device uses an electrochemical workstation (Shanghai Chenhua CHIE760). The wire is peeled off, the copper wire is cut out, and the top and bottom ends of the microchannel are fixed with photocuring glue as the first electrode and the second electrode respectively. The first electrode and the second electrode are connected with a wire with an alligator clip. The alligator clip clamps the first electrode and the second electrode, and the plug is inserted into the positive and negative poles of the electrochemical workstation. When the microchannel is filled with working fluid, a circuit is formed. The microchannel 21 on the substrate 2 is realized by opening a groove 22 on the surface of the substrate 2. The width of the groove 22 is 100μm, the depth is 170μm, and the length is 20mm. The substrate 2 is fixed to the bottom plate of the liquid reservoir 11 by photocuring glue, and the angle between the substrate 2 and the bottom plate of the liquid reservoir 11 is 45°. The position of the xenon lamp is adjusted so that the light is vertically irradiated to the middle position of the microchannel 21 on the substrate 2. A microscope is placed above the base plate 2 to observe the generation of bubbles in the microchannel 21. The working fluid in the reservoir 11 is deionized water.

[0058] After the monitoring system is set up, the electrochemical workstation is turned on, the xenon lamp is turned on, and a constant voltage of 1V is applied to the microchannel 21. The current data is collected every 0.02s, that is, 50 samples are collected per second, and uploaded to the computer in real time. A plot is drawn with time (s) as the horizontal axis and current (10-10A) as the vertical axis to describe the effect of the change of bubble behavior in the microchannel over time on the microchannel current. Take one section of the bubble growth process (4740s-4790s of illumination) as an example. Figure 5 As shown, the xenon lamp current is 1.508A and the power density is 2.42×106W / m 2 After 4740 seconds of illumination, the silver nanoparticles deposited in the grooves provided nucleation sites, generating numerous tiny bubbles. These tiny bubbles can be considered insulators, and their presence reduced the amount of electrical conductors within the microchannel, causing a drop in current. During the initial illumination period (0-50 seconds), the photothermal material's low photothermal conversion energy made it difficult to provide energy for bubble growth. Consequently, fewer tiny bubbles formed within the microchannel, resulting in a higher corresponding current.

[0059] Figure 5As can be seen in the figure, compared to the initial illumination (0-50s), the current value corresponding to 4740s of illumination is smaller. This is because after a long period of light-to-heat conversion, the photothermal material accumulates heat in the microchannel, providing the energy required for bubble growth. At this time, the microchannel is already filled with many tiny bubbles. In the illumination interval of 4760s-4762s, the microchannel current rises sharply. The reason is that the tiny bubbles gather to form large bubbles and are discharged through the end of the microchannel connected to the atmosphere. As the large bubbles gradually leave, the current in the microchannel rises accordingly. After the large bubbles completely leave the microchannel, the microchannel automatically replenishes the fluid and the current reaches a peak. Immediately afterwards, new tiny bubbles will continue to form at the nucleation sites, followed by a decrease in current, gradually returning to a state where the microchannel is filled with tiny bubbles. When the photothermal material nanosilver particles are continuously exposed to light, the current in the microchannel will undergo periodic changes as described above. Figure 6 Shows the comparison before and after illumination of the microchannel: Figure 6 The left picture shows the microchannel without light illumination, with no bubbles generated; the right picture shows bubbles generated in the microchannel under light illumination.

[0060] Figure 7 The current variation trend from 0 to 5000 seconds of illumination is shown. It can be seen that as bubbles are expelled, the current repeats a cycle of increasing, then decreasing, and then stabilizing. The peak current gradually decreases with the illumination time. This is because as the energy from photothermal conversion accumulates, the generation rate of bubbles in the microchannel accelerates. Although bubbles are constantly expelled, more bubbles remain in the microchannel compared to the previous cycle. Therefore, the peak current achieved during each bubble expulsion cycle also decreases. The slope of the smooth curve formed by connecting the current peaks shows an overall decreasing trend.

Claims

1. A micro / nano bubble monitoring system based on electrical signals, characterized by: It includes a detection platform (1), a base plate (2), a condenser (3), a current detection device (4) and a computer (5); A microchannel (21) is provided on the base plate (2), and a light-to-heat conversion layer (21a) is provided on the surface of the microchannel (21), so that external light can pass through the microchannel (21) and reach the light-to-heat conversion layer (21a); The main body of the detection platform (1) is a liquid reservoir (11) for storing a working fluid, the base plate (2) is fixed in the liquid reservoir (11) at an angle, the bottom of the base plate (2) is immersed in the working fluid in the liquid reservoir (11), the working fluid enters the microchannel (21) from the bottom end of the microchannel (21), and the top end of the microchannel (21) is connected to the atmosphere to discharge bubbles; The condenser (3) is arranged obliquely above the base plate (2) and collects external light into a light beam that irradiates the light-heat conversion layer (21a) of the microchannel (21), wherein the external light is light that can excite the material of the light-heat conversion layer (21a) to convert light energy into heat energy; A first electrode (41) is provided at the top end of the microchannel (21), and a second electrode (42) is provided at the bottom end of the microchannel (21). The first electrode (41) and the second electrode (42) are respectively connected to a current detection device (4) via a wire (43); and the current detection device (4) is connected to the computer (5) via a data line.

2. The micro / nano bubble monitoring system based on electrical signals according to claim 1, characterized in that: It also includes a light source generator (6) for providing a light source, wherein the light source generator (6) is preferably a sunlight simulation device, and the sunlight simulation device is preferably a xenon lamp.

3. The micro / nano bubble monitoring system based on electrical signals according to claim 1, characterized in that: It also includes a bubble visualization observation device (7), which is a scanning electron microscope, an atomic force microscope or a high-speed camera.

4. The micro / nano bubble monitoring system based on electrical signals according to claim 1, characterized in that: The top and bottom ends of the microchannel (21) are both provided with electrode mounting holes for mounting electrodes; The angle between the base plate (2) and the bottom plate of the detection platform (1) is 30° to 90°, preferably 40° to 60°; the angle between the light beam of external illumination focused by the condenser (3) and the base plate (2) is 45° to 90°.

5. The micro / nano bubble monitoring system based on electrical signals according to claim 1, characterized in that: A groove (22) is provided on the upper surface of the base plate (2), and a light-to-heat conversion layer (21a) is provided on the surface of the groove (22); a transparent cover sheet (23) is provided on the base plate (2), which is used to cover the upper surface of the base plate (2) to form the microchannel (21) between the groove (22) and the transparent cover sheet (23); the bottom end of the microchannel (21) is in contact with the working fluid in the liquid reservoir (11), and the top end is connected to the atmosphere; the material of the base plate (2) is a non-conductive material that is resistant to heat emitted by the light source, preferably polydimethylsiloxane (PDMS) or quartz glass.

6. The micro / nano bubble monitoring system based on electrical signals according to claim 5, characterized in that: The transparent cover (23) is a glass cover; The groove (22) has a width of 50 to 500 μm, a depth of 70 to 700 μm, and a length of 10 to 60 mm.

7. The micro / nano bubble monitoring system based on electrical signals according to claim 1, characterized in that: The base plate (2) is made of a transparent material and has the microchannel (21) formed therein. Both ends of the microchannel (21) reach the edge of the base plate (2). The base plate (2) is made of a light-transmitting material that is non-conductive and resistant to heat from a light source, preferably quartz glass. The microchannel (21) has a width of 50 to 500 μm, a depth of 70 to 700 μm, and a length of 10 to 60 mm.

8. The micro / nano bubble monitoring system based on electrical signals according to claim 1, characterized in that: The condenser (3) is a convex lens; The light-to-heat conversion layer (21a) is a nanosilver particle layer, a polypyrrole or a carbon nanotube coating; The current detection device (4) is an electrochemical workstation or a current acquisition card, and the first electrode (41) and the second electrode (42) are both copper electrodes; The working fluid in the microchannel (21) is a low-boiling-point fluid, preferably water or seawater.

9. The micro / nano bubble monitoring system based on electrical signals according to claim 1, characterized in that: It also includes an anti-vibration platform (8), and the detection platform (1) is arranged on the anti-vibration platform (8) to reduce or eliminate the influence of device shaking on the detection results; A light shielding plate (24) is also provided on the base plate (2), and the light shielding plate (24) covers the upper portion of the microchannel (21) that is not focused by the light spot.

10. A method for monitoring micro / nano bubbles, characterized in that: Monitoring using the monitoring system according to any one of claims 1 to 9 comprises the following steps: A working fluid is added to a liquid reservoir (11), external light is directed toward a condenser lens (3), a current detection device (4) and a computer (5) are turned on, and changes in the current in the microchannel (21) are recorded, thereby monitoring the generation of micro / nano bubbles in the microchannel (21).

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