Device system and method for observing liquid bridge morphology and liquid bridge force among viscous particles

Abstract

The invention provides a device system and method for observing liquid bridge morphology and liquid bridge force among viscous particles. The device system comprises a first XYZ three-axis displacement table, a high-speed microscopic shooting device, a liquid bridge forming device, a precise force monitoring assembly, a second XYZ three-axis displacement table, an XYZ three-axis nanometer positioning platform, a Z-axis displacement table, a light source and a windproof device. According to the invention, the precise force monitoring assembly is adopted to realize accurate measurement of liquid bridge force among viscous particles in static and dynamic researches; a high-speed microscopic shooting device is used for recording the formation and fracture process of liquid bridges among the viscous particles; and the liquid bridge force among the viscous particles is researched from multiple directions by using a three-axis displacement table. The method disclosed by the invention is simple to operate, can be used for researching the liquid bridge morphology and the liquid bridge force change rule under the conditions of different liquid volumes, different particle distances, different particle size ratios and different separation speeds, and provides a theoretical basis for the utilization of viscous particles in the industrial process.

Description

Technical Field

[0001] The present invention relates to the technical field of micro-force measurement, and particularly to a device system and method for observing the morphology and liquid bridge force of liquid bridges between viscous particles. Background Art

[0002] Viscous particles widely exist in natural and artificial environments. Due to the presence of liquid, viscous particulate matter often exhibits different characteristics from dry particles. The liquid forms liquid bridges between the particles, and the liquid bridge force can significantly affect the macroscopic flow characteristics of the particles. In order to better describe the interaction and flow behavior of the viscous particle system from a macroscopic perspective, it is necessary to study the interaction between the liquid and the particles from a microscopic perspective, describe the formation of the liquid bridge between the particles in multiple aspects, obtain the variation law of the liquid bridge force between the particles under the influence of relevant parameters, and then establish a liquid bridge force model to describe the interaction between the viscous particles.

[0003] The liquid bridge force between particles is tiny and has a relatively small acting range. Previous studies usually used atomic force microscopy (AFM), surface force apparatus (SFA), and centrifugation techniques for measurement. However, these methods have some challenges. On the one hand, the required instruments are highly demanding and inconvenient to operate. On the other hand, the measurement of the liquid bridge force is more at the static and quasi-static levels, making it difficult to quantify the influence of the distance and relative velocity between the particles on the liquid bridge force. The AFM measurement method has strict requirements for the particles matching the probe because the probe itself has a great influence on the measurement results. It is usually applicable to particles in the nano-micron scale, and the acting range is small. Generally, it can only measure the force in a local tiny area and cannot obtain the force in the entire liquid bridge area. When the probe is extremely close to the sample, the influence of electrostatic force, electric double layer force, and chemical forces (such as hydrogen bonds) becomes very obvious, making the analysis and interpretation of the obtained data complex. It is very difficult to separately determine the liquid bridge force interaction between the particles and requires professional knowledge and experience. The surface force apparatus is limited to substances such as mica and gold that can be coated on highly curved crossed cylinders, which limits the measurement of the liquid bridge force between soft materials. Although the centrifugation method can perform viscous measurement experiments on a large number of samples in a relatively short time, it cannot quantitatively characterize the influence of the distance between the particle surfaces.

[0004] In addition, most of the studies on the liquid bridge force between particles have a relatively small number of samples, resulting in insufficient universality and representativeness of the obtained results. Moreover, the particle materials, liquid types, etc. used in the studies are also relatively limited and difficult to comprehensively cover the actual application situations. On the other hand, the existing liquid bridge force measurement methods have problems such as difficult operation, insufficient accuracy, narrow application range, and high price. Therefore, there is an urgent need to develop new experimental technical means to directly measure the liquid bridge force between various types of viscous particles and achieve accurate, convenient, and real-time data acquisition of the liquid bridge morphology and the magnitude of the liquid bridge force.

[0005] There are various available formulas for the geometric description of the liquid bridge morphology between particles. The most important one is the Young-Laplace equation, which indicates that the mean curvature of the liquid bridge surface is constant, and the breaking distance and liquid bridge force of the liquid bridge can be obtained by solving the Young-Laplace equation. A large number of experiments have verified the accuracy and reliability of the Young-Laplace equation in describing the liquid bridge. However, most studies are carried out under various ideal assumptions, usually assuming that a symmetric concave liquid bridge is formed between particles. In reality, due to limitations in distance and liquid volume, the liquid bridge between particles is not always symmetrically concave, and the ideal assumptions may not accurately describe the liquid bridge morphology and liquid bridge force under real conditions.

[0006] The liquid bridge morphology has a significant impact on the liquid bridge force. The characteristics of the liquid bridge morphology formed between actual particles are determined by various factors, including liquid volume, interfacial tension, solid surface wettability, particle properties, and particle spacing. In most studies, the contact angle between particles is usually regarded as a fixed value. However, in an actual system, due to external forces, as well as differences in particle surface properties, liquid volume, and particle spacing, the apparent contact angle of the interaction between the liquid and the particle surface often changes. The change in the apparent contact angle will cause the three-phase contact line to move, thereby changing the liquid bridge morphology and ultimately affecting the liquid bridge force. Therefore, it is very necessary to accurately measure the liquid bridge morphology and the magnitude of the liquid bridge force between particles for establishing an accurate model of the liquid bridge force.

[0007] CN116295605A discloses a device and method for analyzing the liquid bridge suction and breaking distance between irregular particles. The device includes an upper mounting rod, a lower mounting rod, a micrometer, a microbalance, and a photographing device. This device is used to analyze the liquid bridge suction and breaking distance between irregular particles, and can accurately measure the particle morphology, the solid-liquid-gas three-phase contact angle, the liquid bridge volume, and their effects on the liquid bridge suction and breaking distance of irregular particles.

[0008] CN113252515A discloses a test method for a wet particle liquid bridge tensile-compressive mechanical property tester, including the initial setting of the tester, the liquid bridge test for controlling the liquid bridge volume, the liquid bridge test for controlling the matrix suction, and setting the liquid bridge test type through the control system, namely the liquid bridge tensile test, the liquid bridge compressive test, and the liquid bridge tensile-compressive cyclic test. This method can not only carry out liquid bridge tensile, compressive, and cyclic tests within a set range under the condition of automatically and accurately controlling the liquid bridge volume or matrix suction, but also combine an industrial electron microscope with corresponding image processing methods to monitor the change law of the key geometric parameters of the meniscus throughout the process.

[0009] However, the above device for analyzing and testing the liquid bridge force between particles still has problems such as insufficient test accuracy and inability to study the interaction between particles comprehensively and from multiple angles. Summary of the Invention

[0010] In view of the problems existing in the prior art, the present invention provides a device system and method for observing the liquid bridge morphology and liquid bridge force between viscous particles. A precision force monitoring component is arranged below the liquid bridge forming device to accurately measure the change of the liquid bridge force between viscous particles; moreover, a first XYZ three-axis displacement stage, a second XYZ three-axis displacement stage, an XYZ three-axis nano-positioning platform, and a high-speed microscopic imaging device are provided to realize the research on the liquid bridge force and liquid bridge morphology between viscous particles from multiple directions and angles.

[0011] To achieve this purpose, the present invention adopts the following technical solutions:

[0012] In a first aspect, the present invention provides a device system for observing the liquid bridge morphology and liquid bridge force between viscous particles. The device system includes a first XYZ three-axis displacement stage, a high-speed microscopic imaging device, a liquid bridge forming device, a precision force monitoring component, a second XYZ three-axis displacement stage, an XYZ three-axis nano-positioning platform, a Z-axis displacement stage, a light source, and a windproof device;

[0013] The high-speed microscopic imaging device is arranged on the first XYZ three-axis displacement stage;

[0014] The liquid bridge forming device and the precision force monitoring component are sequentially arranged on the second XYZ three-axis displacement stage;

[0015] The light source is arranged on one side of the liquid bridge forming device away from the high-speed microscopic imaging device; the light source is arranged on the second XYZ three-axis displacement stage;

[0016] The liquid bridge forming device, the XYZ three-axis nano-positioning platform, and the Z-axis displacement stage are sequentially connected;

[0017] The liquid bridge forming device, the precision force monitoring component, the second XYZ three-axis displacement stage, and the light source are all arranged inside the windproof device.

[0018] The device system for observing the liquid bridge morphology and liquid bridge force between viscous particles according to the present invention is simple to operate. The precision force monitoring component can read the change of the liquid bridge force in the liquid bridge forming device in real time; the high-speed microscopic imaging device can accurately record the change of the liquid bridge morphology; the device system can be applied to study the influence laws of liquid volume, particle spacing, particle size, and particle separation speed on the liquid bridge morphology and liquid bridge force.

[0019] The windproof device according to the present invention can be a glass windproof cover, which can prevent the interference of the external environment.

[0020] Preferably, the device system further includes a data and image analysis and processing device.

[0021] The data and image analysis and processing device according to the present invention can be a computer.

[0022] Preferably, the data and image analysis and processing device is electrically connected to a high-speed microscopic imaging device, a precision force monitoring component, a light source, a second XYZ three-axis displacement stage, and an XYZ three-axis nano-positioning platform respectively.

[0023] Preferably, the liquid bridge forming device includes an upper particle fixing platform, an upper particle, a lower particle, and a lower particle fixing platform, which are arranged in sequence from top to bottom.

[0024] Preferably, the upper particle fixing platform is connected to the XYZ three-axis nano-positioning platform.

[0025] Preferably, the lower particle fixing platform is connected to the precision force monitoring component.

[0026] In the present invention, the upper particle fixing device is first connected to the XYZ three-axis nano-positioning platform by screws. In order not to affect the experimental operation, the XYZ three-axis nano-positioning platform is extended outward, and grooves are made on the platform for better fixing of the upper particle. The lower particle is bonded to the lower particle fixing platform with glue, and then the lower particle fixing platform is connected to the precision force monitoring component with screws. After fixing the upper and lower particles under study on the platform, it is necessary to ensure that their initial positions are not offset to avoid affecting the experimental process.

[0027] Preferably, the device system further includes a micro liquid syringe for injecting liquid between the upper particle and the lower particle to form a liquid bridge.

[0028] Preferably, the high-speed microscopic imaging device is further connected to a horizontal calibrator for calibrating the position of the imaging device to avoid errors caused by the deviation of the installation position of the high-speed microscopic imaging device.

[0029] Preferably, the number of the high-speed microscopic imaging devices is two, which are respectively arranged in front of and on the left side of the liquid bridge formed by the upper particle and the lower particle, for capturing the morphology of the liquid bridge formed between the two particles from the front and the side, facilitating subsequent processing of the photos to extract the liquid bridge contour information, and avoiding errors caused by the positions not being in the same vertical direction.

[0030] In the present invention, both of the two high-speed microscopic imaging devices are connected to the first XYZ three-axis displacement stage for regulating the initial positions of the particles. At the same time, a transfer gasket is used at the connection between the high-speed microscopic imaging device and the first XYZ three-axis displacement stage, so that the high-speed microscopic imaging device can rotate along a 360° direction and can approach and move away from the particles according to the magnification for better imaging. The high-speed microscopic imaging device can select a high-resolution imaging device with a resolution of 2048×1536, and the optical magnification of the imaging device is 0.7 - 7 times. The data acquisition can be manually recorded or continuous photos can be taken at a frequency of 20 frames per second, mainly for recording the static and dynamic liquid bridge morphologies.

[0031] Preferably, the light source includes an LED light source because the precision force monitoring component has high environmental requirements and uses a cold light source to avoid affecting the liquid bridge measurement process.

[0032] Preferably, the device system further includes a first support platform, a second support platform, and an optical platform.

[0033] Preferably, the first XYZ three-axis displacement stage is arranged on the first support platform.

[0034] Preferably, the second XYZ three-axis displacement stage is arranged on the second support platform.

[0035] Preferably, both the first support platform and the second support platform are arranged on the optical platform.

[0036] In a second aspect, the present invention also provides a method for observing the liquid bridge morphology and liquid bridge force between viscous particles. The method is carried out by using the device system for observing the liquid bridge morphology and liquid bridge force between viscous particles described in the first aspect. The method includes a static observation method and a dynamic observation method;

[0037] The static observation method includes a method for observing the liquid bridge morphology and liquid bridge force under conditions of different liquid volumes, different particle spacings, and different particle size ratios;

[0038] The dynamic observation method includes a method for observing the liquid bridge morphology and liquid bridge force at different separation speeds.

[0039] The method for observing the liquid bridge morphology and liquid bridge force between viscous particles according to the present invention studies the liquid bridge morphology and liquid bridge force between viscous particles from both static and dynamic aspects. By performing gray processing and edge extraction on the liquid bridge images captured by the high-speed microscopic imaging device, the apparent contact angles under different working conditions (different liquid volumes, different particle spacings, different particle size ratios, and different separation speeds) can be obtained, and the intrinsic contact angle can be corrected to make the theoretical value more consistent with the experimental value.

[0040] The method according to the present invention can study different experimental particles, such as equal-diameter particles, unequal-diameter particles, smooth particles, rough particles, spherical particles, or non-spherical particles, etc. The selection range of the liquid between the particles is also relatively wide, and existing liquids with poor volatility can be used to avoid experimental errors caused by liquid volatilization during the experiment.

[0041] Preferably, the method for observing the liquid bridge morphology and liquid bridge force under conditions of different liquid volumes, different particle spacings, and different particle size ratios includes the following steps:

[0042] (1) After turning on the light source, use the Z-axis displacement stage, the second XYZ three-axis displacement stage, and the XYZ three-axis nano-positioning platform to preliminarily determine the positions of the precision force monitoring component and the upper and lower particles in the liquid bridge forming device; use the first XYZ three-axis displacement stage and the high-speed microscopic imaging device to align the central axes of the upper and lower particles in the same vertical direction but without contact.

[0043] (2) Use a micro liquid syringe to inject liquid onto the center of the upper surface of the lower particle. After the reading of the precision force monitoring component stabilizes, record the data as F 1 , and then, after adjusting the upper particle to contact the lower particle through the Z-axis in the XYZ three-axis nano-positioning platform and adjusting the upper particle to the set position, record the data as F 2 after the reading of the precision force monitoring component stabilizes. Obtain the magnitude of the static liquid bridge force F = F 2 - F 1 at the set particle spacing according to the data recorded by the precision force monitoring component before and after the formation of the liquid bridge; simultaneously, capture the liquid bridge image through the high-speed microscopic imaging device to determine the morphology of the liquid bridge formed between the two particles.

[0044] (3) Set different spacings between the upper and lower particles, and repeat step (2) to obtain the liquid bridge force and liquid bridge morphology under different particle spacing conditions with the same liquid bridge volume and the same particle size.

[0045] (4) Use a micro liquid syringe to inject liquids of different volumes onto the center of the upper surface of the lower particle. While keeping the spacing between the upper and lower particles the same and the particle sizes of the two particles the same, repeat step (2) to obtain the liquid bridge force and liquid bridge morphology under different liquid volume conditions with the same particle spacing and the same particle size.

[0046] (5) Replace the upper and lower particles with different particle sizes, and repeat step (2) to obtain the liquid bridge force and liquid bridge morphology under different particle size ratio conditions with the same liquid bridge volume and the same particle spacing.

[0047] Preferably, the method for observing the liquid bridge morphology and liquid bridge force at different separation speeds includes the following steps:

[0048] (1) After turning on the light source, use the Z-axis displacement stage, the second XYZ three-axis displacement stage, and the XYZ three-axis nano-positioning platform to preliminarily determine the positions of the precision force monitoring component and the upper and lower particles in the liquid bridge forming device; use the first XYZ three-axis displacement stage and the high-speed microscopic imaging device to align the central axes of the upper and lower particles in the same vertical direction but without contact.

[0049] (2) Use a micro liquid syringe to inject liquid onto the center of the upper surface of the lower particle. After the reading of the precision force monitoring component stabilizes, record the data as F 3, and then, after adjusting the upper and lower particles to contact each other through the Z-axis of the XYZ three-axis nano-positioning platform, set the Z-axis moving speed of the XYZ three-axis nano-positioning platform to make the upper particle move away from the lower particle at a certain speed; at the same time, use a high-speed microscopic imaging device and a precision force monitoring component to record the data of the changing liquid bridge morphology and force F during this process 4 in real time until the liquid bridge breaks, and calculate the magnitude of the dynamic liquid bridge force F' = F at the set separation speed 4 -F 3 .

[0050] Before conducting the observation experiment of the method of the present invention, use glue to fix the upper particle on the upper particle fixing platform and the lower particle on the lower particle fixing platform respectively; preheat the precision force monitoring component before use.

[0051] The judgment criterion for the stable indication of the precision force monitoring component described in the present invention is that the indication change of the precision force monitoring component does not exceed 2 μN within 30 s. After the indication of the precision force monitoring component is stable, zero its indication. After the liquid is dropped and the indication of the precision force monitoring component is stable, record the data of the precision force monitoring component within 10 s and take its average value.

[0052] Preferably, the particle size is 50 μm to 10 mm, for example, it can be 50 μm, 80 μm, 100 μm, 500 μm, 700 μm, 900 μm, 1 mm or 10 mm, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0053] Preferably, the material of the particle includes any one of glass, plastic or metal.

[0054] Preferably, the parameters characterizing the liquid bridge morphology include the neck width, the semi-filling angle and the contact angle.

[0055] Preferably, the data information of the high-speed microscopic imaging device, the precision force monitoring component, the light source, the second XYZ three-axis displacement stage and the XYZ three-axis nano-positioning platform is transmitted to the data and image analysis and processing device for recording and processing.

[0056] The method of the present invention further includes performing binarization processing on the liquid bridge contour photo taken by the high-speed microscopic imaging device using ImageView software, and then performing contour extraction using MATLAB to obtain the liquid bridge information between the particles. During the contour extraction process, it is necessary to ensure that the pixels of each photo are the same under the same working conditions to achieve the unity of the data extraction process. MATLAB is mainly used to extract the pixel points in the photo, so it is necessary to determine the center position and radius. Since the taken photo has a certain magnification, it is necessary to scale the corresponding pixel point coordinates with the actual size.

[0057] For the determination of the contact angle, the CAD-assisted tangent method is adopted. A line is drawn from the center of the circle to the solid-liquid contact point and its tangent is made. Another line starts from the contact point along the liquid bridge interface. The included angle between the two lines is the contact angle to be determined.

[0058] As a preferred technical solution of the present invention, the method for observing the liquid bridge morphology and liquid bridge force under different liquid volumes, different particle spacings and different particle size ratios includes the following steps:

[0059] (1) After turning on the light source, use the Z-axis displacement stage, the second XYZ three-axis displacement stage and the XYZ three-axis nano-positioning platform to preliminarily determine the positions of the precision force monitoring component and the upper and lower particles in the liquid bridge forming device; use the first XYZ three-axis displacement stage and the high-speed microscopic imaging device to make the central axes of the upper and lower particles in the same vertical direction but not in contact.

[0060] (2) Use a micro liquid syringe to inject liquid into the center of the upper surface of the lower particle. After the indication of the precision force monitoring component is stable, record the data as F 1 , and then adjust the upper particle to contact the lower particle through the Z-axis in the XYZ three-axis nano-positioning platform, and then adjust the upper particle to the set position. After the indication of the precision force monitoring component is stable, record the data as F 2 . According to the data recorded by the precision force monitoring component before and after the formation of the liquid bridge, obtain the magnitude of the static liquid bridge force F = F 2 -F 1 ; at the same time, take a liquid bridge image through the high-speed microscopic imaging device to determine the liquid bridge morphology formed between the two particles.

[0061] (3) Set different spacings between the upper and lower particles, and repeat step (2) to obtain the liquid bridge force and liquid bridge morphology under different particle spacing conditions with the same liquid bridge volume and the same particle size.

[0062] (4) Use a micro liquid syringe to inject different volumes of liquid into the center of the upper surface of the lower particle. Keep the spacing between the upper and lower particles the same and the particle sizes of the two particles the same, and repeat step (2) to obtain the liquid bridge force and liquid bridge morphology under different liquid volume conditions with the same particle spacing and the same particle size.

[0063] (5) Replace the upper and lower particles with different particle sizes, and repeat step (2) to obtain the liquid bridge force and liquid bridge morphology under different particle size ratio conditions with the same liquid bridge volume and the same particle spacing.

[0064] The method for observing the liquid bridge morphology and liquid bridge force at different separation speeds includes the following steps:

[0065] (1) After turning on the light source, use the Z-axis displacement stage, the second XYZ three-axis displacement stage, and the XYZ three-axis nano-positioning platform to preliminarily determine the positions of the precision force monitoring component and the upper and lower particles in the liquid bridge forming device; use the first XYZ three-axis displacement stage and the high-speed microscopic imaging device to align the central axes of the upper and lower particles in the same vertical direction but without contact.

[0066] (2) Use a micro liquid syringe to inject liquid onto the center of the upper surface of the lower particle. After the reading of the precision force monitoring component stabilizes, record the data as F 3 . Then, after adjusting the upper particle to contact the lower particle through the Z-axis of the XYZ three-axis nano-positioning platform, set the Z-axis movement speed of the XYZ three-axis nano-positioning platform to make the upper particle move away from the lower particle at a certain speed; simultaneously, use the high-speed microscopic imaging device and the precision force monitoring component to record the changing liquid bridge morphology and the force data F 4 in real time during this process until the liquid bridge breaks, and calculate the magnitude of the dynamic liquid bridge force F' = F 4 - F 3 ;

[0067] The particle size is 50 μm to 10 mm; the material of the particle includes any one of glass, plastic, or metal; the parameters characterizing the liquid bridge morphology include the neck width, the semi-filling angle, and the contact angle; the data information of the high-speed microscopic imaging device, the precision force monitoring component, the light source, the second XYZ three-axis displacement stage, and the XYZ three-axis nano-positioning platform is transmitted to the data and image analysis and processing device for recording; the liquid bridge contour photos taken by the high-speed microscopic imaging device are binarized using ImageView software, and then the contour is extracted using MATLAB to obtain the liquid bridge information between the particles.

[0068] Compared with the prior art, the present invention has at least the following beneficial effects:

[0069] (1) The device system for observing the liquid bridge morphology and liquid bridge force between viscous particles provided by the present invention has a simple structure and a reasonable design, and can accurately measure the changes in the liquid bridge morphology and liquid bridge force between viscous particles under different working conditions, providing a theoretical basis for the utilization of viscous particles in industrial processes.

[0070] (2) The method for observing the liquid bridge morphology and liquid bridge force between viscous particles provided by the present invention obtains a three-dimensional imaging diagram of the liquid bridge through two high-speed microscopic imaging devices, and uses image processing technology to perform gray-scale processing and edge extraction on the liquid bridge image to obtain a more accurate apparent contact angle. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Figure 1 is a schematic diagram of a device system for observing the liquid bridge morphology and liquid bridge force between viscous particles provided in the specific embodiment of the present invention.

[0072] Figure 2 It is an observation and magnification view of the liquid bridge forming device provided in the specific implementation manner of the present invention.

[0073] Figure 3 It is a method flow chart for observing the liquid bridge morphology and liquid bridge force under conditions of different liquid volumes, different particle spacings, and different particle size ratios in the specific implementation manner of the present invention.

[0074] Figure 4 It is a schematic diagram of the formation of a liquid bridge between the upper particle and the lower particle in the specific implementation manner of the present invention.

[0075] Figure 5 It is a schematic diagram of contour extraction of the liquid bridge formed between the upper particle and the lower particle in the specific implementation manner of the present invention.

[0076] Figure 6 It is a graph of the experimental results of the liquid bridge force under different particle spacing conditions in the specific implementation manner of the present invention.

[0077] Figure 7 It is a graph of the experimental results of the liquid bridge force under different liquid volume conditions in the specific implementation manner of the present invention.

[0078] Figure 8 It is a graph of the experimental results of the liquid bridge force under different particle size ratio conditions in the specific implementation manner of the present invention.

[0079] Figure 9 It is a graph of the experimental results of the dynamic liquid bridge force under different separation speeds in the specific implementation manner of the present invention.

[0080] In the figure: 1 - computer; 2 - first XYZ three-axis displacement stage; 3 - high-speed microscope camera; 4 - horizontal calibrator; 5 - first support platform; 6 - micro liquid syringe; 7 - upper particle fixing platform; 8 - upper particle; 9 - liquid bridge; 10 - lower particle fixing platform; 11 - precision force sensor; 12 - second XYZ three-axis displacement stage; 13 - second support platform; 14 - LED light source; 15 - glass wind shield; 16 - XYZ three-axis nano-positioning platform; 17 - Z-axis displacement stage; 18 - optical platform. Specific implementation manner

[0081] The technical solution of the present invention will be further described below in conjunction with the accompanying drawings and through specific implementation manners.

[0082] The present invention will be further described in detail below. However, the following examples are only simple examples of the present invention and do not represent or limit the scope of the protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0083] It should be understood that in the description of the present invention, the orientation or positional relationship indicated by terms such as "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is 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 operated in a specific orientation, and thus cannot be construed as a limitation on the present invention. In addition, terms such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0084] It should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "arranged", "connected", "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific situations.

[0085] As a specific embodiment of the present invention, a device system for observing the morphology and liquid bridge force between viscous particles is provided, and its schematic diagram is as Figure 1 shown.

[0086] The device system includes a first XYZ three-axis displacement stage 2, a high-speed microscope camera 3, a liquid bridge forming device, a precision force sensor 11, a second XYZ three-axis displacement stage 12, an XYZ three-axis nano-positioning platform 16, a Z-axis displacement stage 17, an LED light source 14, and a glass wind shield 15;

[0087] The high-speed microscope camera 3 is arranged on the first XYZ three-axis displacement stage 2; the liquid bridge forming device and the precision force sensor 11 are sequentially arranged on the second XYZ three-axis displacement stage 12; the LED light source 14 is arranged on one side of the liquid bridge forming device away from the high-speed microscope camera 3; the LED light source 14 is arranged on the second XYZ three-axis displacement stage 12; the liquid bridge forming device, the XYZ three-axis nano-positioning platform 16, and the Z-axis displacement stage 17 are sequentially connected; the liquid bridge forming device, the precision force sensor 11, the second XYZ three-axis displacement stage 12, and the LED light source 14 are all arranged inside the glass wind shield 15.

[0088] The device system further includes a computer 1;

[0089] The computer 1 is electrically connected to the high-speed microscope camera 3, the precision force sensor 11, the LED light source 14, the second XYZ three-axis displacement stage 12, and the XYZ three-axis nano-positioning platform 16 respectively.

[0090] An enlarged view of the observation of the liquid bridge formation device is as Figure 2 shown.

[0091] The liquid bridge formation device includes an upper particle fixing platform 7, an upper particle 8, a lower particle, and a lower particle fixing platform 10 arranged in sequence from top to bottom;

[0092] The upper particle fixing platform 7 is connected to the XYZ three-axis nano-positioning platform 16;

[0093] The lower particle fixing platform 10 is connected to the precision force sensor 11.

[0094] The device system further includes a micro liquid syringe 6 for injecting liquid between the upper particle 8 and the lower particle to form a liquid bridge 9.

[0095] The high-speed microscope camera 3 is also connected to the horizontal calibrator 4;

[0096] The number of the high-speed microscope cameras 3 is two, which are respectively arranged in the front and left of the liquid bridge 9 formed by the upper particle 8 and the lower particle.

[0097] The device system further includes a first support platform 5, a second support platform 13, and an optical platform 18.

[0098] The first XYZ three-axis displacement stage 2 is arranged on the first support platform 5.

[0099] The second XYZ three-axis displacement stage 12 is arranged on the second support platform 13.

[0100] Both the first support platform 5 and the second support platform 13 are arranged on the optical platform 18.

[0101] In this specific embodiment, the accuracy of the precision force sensor 11 is 0.01 μN, the minimum accuracy of the XYZ three-axis nano-positioning platform 16 is 10 nm, and the minimum moving speed of the Z-axis displacement stage 17 is 100 nm / s.

[0102] As a specific embodiment of the present invention, a method for observing the morphology and force of the liquid bridge between viscous particles is further provided. The method is carried out by using the above device system for observing the morphology and force of the liquid bridge between viscous particles; the method includes a static observation method and a dynamic observation method.

[0103] In this specific embodiment, the materials of the upper particle 8 and the lower particle used are both glass; the parameters characterizing the morphology of the liquid bridge 9 include the neck width, the semi-filling angle, and the contact angle.

[0104] Before each observation experiment starts, the glass particles to be used are ultrasonically cleaned in an ultrasonic cleaner for 3 hours, and then cleaned with anhydrous ethanol with a concentration of 99% to avoid the influence of impurities on the particle surface on the experimental process. The cleaned glass particles are placed in a beaker sealed with a film and dried in an oven at 60°C for 1 hour to remove the moisture and anhydrous ethanol on the particle surface and prevent them from mixing with the experimental liquid.

[0105] The static observation method includes the method of observing the liquid bridge morphology and liquid bridge force under different liquid volumes, different particle spacings, and different particle size ratios. The flowchart is as Figure 3 shown. It includes the following steps:

[0106] (1) After turning on the LED light source 14, use the Z-axis displacement stage 17, the second XYZ three-axis displacement stage 12, and the XYZ three-axis nano-positioning platform 16 to preliminarily determine the positions of the precision force sensor 11 and the upper particle 8 and the lower particle in the liquid bridge forming device; use the first XYZ three-axis displacement stage 2 and the high-speed microscope camera 3 to make the central axes of the upper particle 8 and the lower particle in the same vertical direction but not in contact.

[0107] (2) Use a micro liquid syringe 6 to inject liquid onto the center of the upper surface of the lower particle. After the reading of the precision force sensor 11 is stable, record the data as F 1 , and then after adjusting the upper particle 8 to contact the lower particle through the Z-axis in the XYZ three-axis nano-positioning platform 16, adjust the upper particle 8 to the set position. After the reading of the precision force sensor 11 is stable, record the data as F 2 . According to the data recorded by the precision force sensor 11 before and after the formation of the liquid bridge 9, obtain the magnitude of the static liquid bridge force F = F 2 -F 1 ; at the same time, take an image of the liquid bridge 9 through the high-speed microscope camera 3 to determine the morphology of the liquid bridge 9 formed between the two particles. The schematic diagram of the liquid bridge is as Figure 4 shown. Figure 4 where R 1 , R 2 are the particle radii, R out is the outer curvature radius, R in is the inner curvature radius, r is the liquid bridge width, S is the particle spacing, β 1 , β 2 is the semi-filling angle, θ 1 , θ 2 is the solid-liquid contact angle. The schematic diagram of the liquid bridge contour extraction is as Figure 5 shown.

[0108] (3) Set the dimensionless spacing S between the upper particle 8 and the lower particle *They are 0.075, 0.15, 0.25, 0.30, 0.35, 0.45, 0.50, 0.60, and 0.70 respectively. Repeat step (2) to obtain the liquid bridge force and liquid bridge morphology under different particle spacing conditions when the liquid bridge volume is 0.2 μL, the upper particle 8 and the lower particle have the same particle size of 3 mm and 5 mm respectively; the experimental results of the liquid bridge force are as Figure 6 shown. (The dimensionless spacing S * is the ratio of the particle spacing to the radius of the upper particle 8)

[0109] It can be seen from the figure that as the particle spacing increases, the liquid bridge force between the upper particle 8 and the lower particle gradually decreases; among the test groups with larger particle sizes, the liquid bridge force between the particles is greater than that of the test groups with smaller particle sizes.

[0110] (4) The micro liquid syringe 6 injects different volumes of liquid, namely 0.6 μL, 0.8 μL, 1.0 μL, 1.4 μL, 1.8 μL, 2.0 μL, 2.5 μL, 3.0 μL, 3.5 μL, and 4.0 μL respectively, into the center of the upper surface of the lower particle, and keeps the dimensionless spacing S * between the upper particle 8 and the lower particle the same, S Figure 7 = 0.4. When the upper particle 8 and the lower particle have the same particle size of 3 mm and 5 mm respectively, repeat step (2) to obtain the liquid bridge force and liquid bridge morphology under different liquid volume conditions with the same particle spacing and the same particle size; the experimental results of the liquid bridge force are as

[0111] shown. It can be seen from the figure that as the liquid volume between the particles increases, the liquid bridge force between the upper particle 8 and the lower particle gradually increases. When the liquid volume is small, the difference in the liquid bridge force between the particles in the test group with smaller particle sizes and the test group with larger particle sizes is not significant; as the liquid volume increases, the liquid bridge force between the particles in the test group with larger particle sizes is greater.

[0112] (5) Replace the upper particle 8 and the lower particle with different particle sizes. The particle size of the upper particle 8 is 3 mm, the particle size of the lower particle is 5 mm, and the particle size of the upper particle 8 is 4 mm, the particle size of the lower particle is 5 mm. Set the dimensionless spacing S * between the upper particle and the lower particle to be 0.075, 0.15, 0.25, 0.30, 0.375, 0.45, 0.50, 0.60, and 0.70 respectively. Repeat step (2) to obtain the liquid bridge force and liquid bridge morphology under different particle size ratio conditions with the same liquid bridge volume of 0.2 μL; the experimental results of the liquid bridge force are as Figure 8 shown.

[0113] It can be seen from the figure that the particle size ratio also has an obvious influence on the liquid bridge force between the particles. As the particle size ratio increases, the liquid bridge force between the particles increases, and as the particle spacing increases, the influence of the particle size ratio gradually decreases.

[0114] The data information of the high-speed microscopic camera 3, the precision force sensor 11, the LED light source 14, the second XYZ three-axis displacement stage 12, and the XYZ three-axis nano-positioning platform 16 is transmitted to the computer 1 for recording; the liquid bridge contour photos taken by the high-speed microscopic camera 3 are binarized using ImageView software, and then the contour is extracted using MATLAB to obtain the liquid bridge information between particles.

[0115] The dynamic observation method includes observing the liquid bridge morphology and liquid bridge force at different separation speeds, and includes the following steps:

[0116] (1) After turning on the LED light source 14, use the Z-axis displacement stage 17, the second XYZ three-axis displacement stage 12, and the XYZ three-axis nano-positioning platform 16 to preliminarily determine the positions of the precision force sensor 11 and the upper particle 8 and the lower particle in the liquid bridge forming device; use the first XYZ three-axis displacement stage 2 and the high-speed microscopic camera 3 to make the central axes of the upper particle 8 and the lower particle in the same vertical direction but not in contact.

[0117] (2) Use a micro liquid syringe 6 to inject liquid into the center of the upper surface of the lower particle. After the reading of the precision force sensor 11 is stable, record the data as F 3 , and then after the upper particle 8 contacts the lower particle through the Z-axis adjustment of the XYZ three-axis nano-positioning platform 16, set the Z-axis movement speed of the XYZ three-axis nano-positioning platform 16 to make the upper particle 8 move away from the lower particle at speeds of 50 μm / s, 100 μm / s, 200 μm / s, 300 μm / s, 400 μm / s, and 500 μm / s; at the same time, use the high-speed microscopic camera 3 and the precision force sensor 11 to record the data F 4 of the changing liquid bridge morphology and force in this process in real time until the liquid bridge breaks, and calculate the magnitude of the dynamic liquid bridge force F' = F 4 - F 3 , and the experimental results of the dynamic liquid bridge force are as Figure 9 shown.

[0118] It can be seen from the figure that the separation speed has an obvious influence on the dynamic liquid bridge between particles and the fracture distance between particles. As the particle separation speed increases, the maximum dynamic liquid bridge force first increases and then decreases, while the fracture distance between particles always increases.

[0119] The data information of the high-speed microscopic camera 3, the precision force sensor 11, the LED light source 14, the second XYZ three-axis displacement stage 12, and the XYZ three-axis nano-positioning platform 16 is transmitted to the computer 1 for recording; the liquid bridge contour photos taken by the high-speed microscopic camera 3 are binarized using ImageView software, and then the contour is extracted using MATLAB to obtain the liquid bridge information between particles.

[0120] In summary, the device system for observing the liquid bridge morphology and liquid bridge force between viscous particles provided by the present invention has a simple structure and reasonable design, and can accurately measure the changes in the liquid bridge morphology and liquid bridge force between viscous particles under different working conditions; and by using two high-speed microscopes to obtain a three-dimensional imaging diagram of the liquid bridge, and using image processing technology to perform gray processing and edge extraction on the liquid bridge image, a more accurate apparent contact angle can be obtained, providing a more accurate theoretical basis for the utilization of viscous particles in industrial processes.

[0121] The applicant declares that the present invention uses the above embodiments to illustrate the detailed structural features of the present invention, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent replacement of the components selected by the present invention, the addition of auxiliary components, and the selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0122] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

Claims

1. A device system for observing the morphology and force of liquid bridges between viscous particles, characterized in that: The device system includes a first XYZ three-axis translation stage, a high-speed microscopic photography device, a liquid bridge forming device, a precision force monitoring component, a second XYZ three-axis translation stage, an XYZ three-axis nanopositioning platform, a Z-axis translation stage, a light source and a windproof device; The high-speed microscopic shooting device is arranged on the first XYZ three-axis translation stage; The liquid bridge forming device and the precision force monitoring component are sequentially arranged on the second XYZ three-axis translation platform; The light source is arranged on a side of the liquid bridge forming device away from the high-speed microscopic photographing device; the light source is arranged on the second XYZ three-axis displacement stage; The liquid bridge forming device, the XYZ three-axis nanopositioning platform and the Z-axis translation stage are connected in sequence; The liquid bridge forming device, the precision force monitoring component, the second XYZ three-axis translation stage and the light source are all arranged in the windproof device.

2. The device system according to claim 1, characterized in that: The device system also includes a data and image analysis and processing device; Preferably, the data and image analysis and processing device is electrically connected to the high-speed microscopic photography device, the precision force monitoring component, the light source, the second XYZ three-axis translation stage and the XYZ three-axis nanopositioning platform respectively.

3. The device system according to claim 1 or 2, characterized in that: The liquid bridge forming device comprises an upper particle fixing platform, upper particles, lower particles and a lower particle fixing platform which are arranged in sequence from top to bottom; Preferably, the upper particle fixing platform is connected to an XYZ three-axis nanopositioning platform; Preferably, the lower particle fixing platform is connected to a precision force monitoring assembly.

4. The device system according to any one of claims 1 to 3, characterized in that: The device system also includes a micro liquid syringe for injecting liquid between the upper particles and the lower particles to form a liquid bridge.

5. The device system according to any one of claims 1 to 4, characterized in that: The high-speed microscopic shooting device is also connected to the horizontal calibration instrument; Preferably, the number of the high-speed microscopic photography devices is two, which are respectively arranged in front of and on the left side of the liquid bridge formed by the upper particles and the lower particles; Preferably, the light source comprises an LED light source.

6. A method for observing the morphology and force of liquid bridges between viscous particles, characterized in that: The method is carried out using the device system for observing the morphology and force of liquid bridges between sticky particles as described in any one of claims 1 to 5; the method includes a static observation method and a dynamic observation method; The static observation method includes a method for observing the liquid bridge morphology and liquid bridge force under conditions of different liquid volumes, different particle spacings and different particle size ratios; The dynamic observation method includes a method for observing the liquid bridge morphology and liquid bridge force at different separation speeds.

7. The method according to claim 6, characterized in that The method for observing the liquid bridge morphology and liquid bridge force under conditions of different liquid volumes, different particle spacings and different particle size ratios comprises the following steps: (1) After turning on the light source, the Z-axis translation stage, the second XYZ three-axis translation stage, and the XYZ three-axis nanopositioning platform are used to preliminarily determine the positions of the precision force monitoring component and the upper particle and the lower particle in the liquid bridge forming device; the first XYZ three-axis translation stage and the high-speed microscopic photography device are used to make the central axes of the upper particle and the lower particle be located in the same vertical direction but not in contact; (2) Use a micro-liquid syringe to inject liquid into the center of the upper surface of the lower particle, and record the data as F1 after the precision force monitoring component reading stabilizes. Then, adjust the upper particle to the set position after the Z-axis of the XYZ three-axis nanopositioning platform adjusts the contact between the upper particle and the lower particle, and record the data as F2 after the precision force monitoring component reading stabilizes. According to the data recorded by the precision force monitoring component before and after the liquid bridge is formed, the static liquid bridge force F=F2-F1 under the set particle spacing is obtained; at the same time, a high-speed microscopic shooting device is used to shoot an image of the liquid bridge to determine the morphology of the liquid bridge formed between the two particles; (3) setting different distances between the upper particles and the lower particles, repeating step (2), and obtaining the liquid bridge force and liquid bridge morphology under different particle spacing conditions with the same liquid bridge volume and the same particle size; (4) Using a micro-liquid syringe, different volumes of liquid are injected into the center of the upper surface of the lower particle, and the spacing between the upper particle and the lower particle is kept the same. When the particle sizes of the two particles are the same, step (2) is repeated to obtain the liquid bridge force and liquid bridge morphology under different liquid volume conditions with the same particle spacing and the same particle size; (5) Replace the upper particles and lower particles of different particle sizes and repeat step (2) to obtain the liquid bridge force and liquid bridge morphology under different particle size ratios with the same liquid bridge volume and the same particle spacing.

8. The method according to claim 6, characterized in that The method for observing the liquid bridge morphology and liquid bridge force at different separation speeds comprises the following steps: (1) After turning on the light source, the Z-axis translation stage, the second XYZ three-axis translation stage, and the XYZ three-axis nanopositioning platform are used to preliminarily determine the positions of the precision force monitoring component and the upper particle and the lower particle in the liquid bridge forming device; the first XYZ three-axis translation stage and the high-speed microscopic photography device are used to make the central axes of the upper particle and the lower particle be located in the same vertical direction but not in contact; (2) Use a micro-liquid syringe to inject liquid into the center of the upper surface of the lower particle. After the indication of the precision force monitoring component stabilizes, the data is recorded as F3. After that, the Z-axis movement speed of the XYZ three-axis nanopositioning platform is adjusted to make the upper particle contact with the lower particle, and the Z-axis movement speed of the XYZ three-axis nanopositioning platform is set to make the upper particle move away from the lower particle at a certain speed. At the same time, the liquid bridge morphology and force data F4 that change during this process are recorded in real time through a high-speed microscope and a precision force monitoring component until the liquid bridge breaks, and the dynamic liquid bridge force F'=F4-F3 at the set separation speed is calculated.

9. The method according to any one of claims 6 to 8, characterized in that: The particle size of the particles is 50 μm to 10 mm; Preferably, the material of the particles includes any one of glass, plastic or metal; Preferably, the parameters characterizing the liquid bridge morphology include neck width, half-filling angle and contact angle.

10. The method according to any one of claims 6 to 9, characterized in that: The data information of the high-speed microscopic shooting device, the precision force monitoring component, the light source, the second XYZ three-axis translation stage and the XYZ three-axis nanopositioning platform are transmitted to the data and image analysis and processing device for recording and processing.

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