Method for measuring flow properties of liquid and device used for droplet observation

Abstract

A method for measuring the flow properties of a liquid and a device used for droplet observation. The method comprises: controlling a droplet to drop from a preset height to a substrate; obtaining a density, a maximum tip radius, a real-time tip height, and an initial tip height of the droplet on the substrate and a test duration from the droplet hitting the substrate to the end of measurement; determining the ratio of a tip height change value to the test duration as a first calculation coefficient, the tip height change value being the difference between the initial tip height and the real-time tip height; and, on the basis of the first calculation coefficient, the droplet density, the maximum tip radius, and the initial tip height, determining a calculated viscosity of the droplet. The present application can measure the calculated viscosity of droplets on the basis of changes in the tip height of the droplets over time, is distinctly different from the existing titration method, rotation method, vibration method and pipe method, and can obtain dynamic changes in the flow properties of droplets.

Description

Method for measuring liquid flow properties and device for observing liquid drops

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is based on the Chinese patent application with application number 202311235916.0 and application date September 22, 2023, and claims the priority of the Chinese patent application. The entire content of the Chinese patent application is hereby introduced into this application as a reference. Technical Field

[0003] The present disclosure relates to the technical field of flow performance measurement, and in particular to a method for measuring the flow performance of liquid and a device for observing liquid droplets. Background Art

[0004] Reactive liquids, such as resins, adhesives, and certain chemicals, undergo a chemical reaction to cure under specific conditions. The physical and chemical properties of these reactive liquids, particularly viscosity and surface tension, can change significantly over time during the curing process. Surface tension and viscosity are important physical and chemical properties of liquids. Viscosity is a measure of the friction between molecules within a liquid, while surface tension is a measure of the interaction between a liquid and its adjacent interfaces. Understanding and accurately measuring the changes in these parameters is crucial for many industrial applications, such as coatings, adhesives, encapsulation, and composites.

[0005] Conventional methods for measuring viscosity and surface tension often rely on discrete measurements of fluid samples at fixed time points. These methods have limitations, such as potentially missing parameter changes at critical moments, requiring large amounts of liquid sample and experimental time, and difficulty capturing the continuity of dynamic changes in the reaction fluid.

[0006] Summary of the Invention

[0007] The present disclosure aims to address at least one of the technical problems existing in the related art. To this end, the present disclosure provides a method for measuring the flow properties of a liquid to address the drawback of the prior art in that it is difficult to continuously and accurately measure the changes in viscosity and surface tension of a liquid throughout its solidification process.

[0008] The present disclosure also provides a device for observing liquid droplets.

[0009] The method for measuring the flow properties of a liquid according to the first embodiment of the present disclosure includes:

[0010] Control the droplets to drip onto the substrate from a preset height;

[0011] Obtaining the droplet density on the substrate, the maximum radius of the tip, the real-time height of the tip, the initial height of the tip, and the test time from the beginning of the droplet landing on the substrate to the end of the measurement;

[0012] Determine that the influencing factors of the tip of the droplet include inertial force and viscous force, and the inertial force is equal to the viscous force, and calculate the calculated viscosity of the droplet. The calculated viscosity of the droplet is related to the first calculation coefficient, the droplet density, the maximum radius of the tip and the initial height of the tip. The first calculation coefficient is equal to the ratio of the tip height change value to the test duration, wherein the tip height change value is the difference between the initial height of the tip and the real-time height of the tip.

[0013] According to one embodiment of the present disclosure, before the step of calculating the viscosity of the droplet,

[0014] Controlling the Weber number of the droplet to be greater than or equal to a set threshold;

[0015] Based on the Weber number being greater than or equal to a set threshold, it is determined that factors affecting the tip of the droplet include inertial force and viscous force, and the inertial force is equal to the viscous force.

[0016] According to one embodiment of the present disclosure, the calculated viscosity of the droplet is determined based on the inertial force being equal to the viscous force, and the calculation formula used is:

[0017] Where ρ is the droplet density;

[0018] η is the calculated viscosity;

[0019] R n is the maximum radius of the tip;

[0020] t is the test time from the droplet starting to fall on the substrate to the end of the test;

[0021] H max is the real-time height of the tip, which changes with the test duration t;

[0022] Solving formula (1) yields:

[0023] From formula (2), we can get:

[0024] Where ΔH max is the tip height change, ΔH max =H0-H max ;

[0025] H0 is the initial height of the tip when the droplet lands on the substrate;

[0026] C1 is the first calculation coefficient, where

[0027] According to one embodiment of the present disclosure, the preset height is greater than or equal to 11.8 cm, and the maximum radius of the tip is between 0.5 mm and 1 mm.

[0028] According to one embodiment of the present disclosure, the method for measuring liquid flow properties further includes:

[0029] controlling the Weber number of the droplet to be less than a set threshold;

[0030] determining, based on the Weber number being less than a set threshold, that factors affecting the tip include viscous force and surface tension, and that the viscous force is equal to the surface tension;

[0031] After the step of calculating the viscosity of the droplet,

[0032] Based on the fact that the viscous force is equal to the surface tension, the ratio of the cube of the tip height change value to the test duration is determined as the second calculation coefficient.

[0033] The surface tension coefficient of the surface tension is calculated using the calculated viscosity, the second calculation coefficient, and the maximum radius of the tip.

[0034] According to one embodiment of the present disclosure, the surface tension coefficient of the surface tension is calculated based on the viscous force being equal to the surface tension, using the calculated viscosity, the second calculation coefficient, and the maximum radius of the tip, and the calculation formula is:

[0035] Where ΔH max is the tip height change, ΔH max =H0-H max ; H0 is the initial height of the tip when the droplet lands on the substrate; H max is the real-time height of the tip, which changes with the test duration t;

[0036] Rn is the maximum radius of the tip;

[0037] η is the calculated viscosity;

[0038] t is the test time from the droplet starting to fall on the substrate to the end of the test;

[0039] Surface tension is F = γR n ;

[0040] γ is the surface tension coefficient, which represents the surface tension per unit length of a straight line segment on the liquid surface;

[0041] Solving formula (3) yields:

[0042] From formula (4), we can get:

[0043] Among them, C2 is the second calculation coefficient, where,

[0044] According to one embodiment of the present disclosure, the preset height is less than 8 cm, and the maximum radius of the droplet tip is between 0.5 mm and 1 mm.

[0045] According to one embodiment of the present disclosure, the calculation formula of the Weber number is:

[0046] Among them, W e is the Weber number;

[0047] ρ is the droplet density;

[0048] v0 is the dripping velocity of the droplet when it just lands on the substrate;

[0049] V0 is the droplet volume;

[0050] γ is the surface tension coefficient, which represents the surface tension per unit length of a straight line segment on the liquid surface;

[0051] The dripping velocity v0 and the droplet volume V0 are obtained when the droplet just lands on the substrate, and the numerical range of the Weber number is adjusted by controlling the dripping velocity v0 and the droplet volume V0.

[0052] According to one embodiment of the present disclosure, the step of controlling the droplets to drip onto the substrate from a preset height further includes:

[0053] Obtaining a flow time of the droplet in a container; wherein the container is used to contain a liquid, and the liquid forms the droplet at an opening of the container;

[0054] Obtaining the dripping time from the start of the droplet dripping to the droplet landing on the substrate;

[0055] The sum of the flow time, the dripping time and the test time is determined to be the total time, and the test time is much shorter than the total time.

[0056] According to one embodiment of the present disclosure, the ratio of the tip height change value to the test duration is determined as the first calculation coefficient.

[0057] The initial height of the tip and multiple real-time heights of the tip within the test duration are obtained, and a linear relationship among the first calculation coefficient, the test duration and the tip height change value is obtained by fitting.

[0058] According to a second aspect of the present disclosure, an apparatus for observing droplets is provided, comprising:

[0059] A droplet injection component, configured to generate droplets, the droplet injection component comprising a first light source emitter, wherein the dripping direction of the droplets is the same as the emitting direction of the first light emitted by the first light source emitter;

[0060] a supporting component, one end of which is connected to the droplet injection component, and the other end of which is connected to a stage, wherein the stage is used to support the light spot sensor;

[0061] A collection component, used for acquiring an image of the liquid droplet falling on the light spot sensor, wherein the collection component is in communication with the light spot sensor;

[0062] Based on the position signal of the first light received by the light spot sensor, the collecting component is controlled to move to a collecting position matching the position signal.

[0063] According to one embodiment of the present disclosure, the droplet injection component includes a droplet nozzle and a liquid adding component, the outlet of the liquid adding component is toward the liquid inlet at one end of the droplet nozzle, and the other end of the droplet nozzle is provided with a spray port, and the first light source emitter is connected to the droplet nozzle and is coaxially arranged with the spray port so that the first light is emitted from the spray port.

[0064] According to one embodiment of the present disclosure, the droplet spray head includes:

[0065] a liquid inlet portion, forming a liquid inlet channel, wherein one end of the liquid inlet channel is provided with the liquid inlet port;

[0066] an injection portion, forming an injection channel, the injection portion being connected to the liquid inlet portion, the injection channel being connected to the other end of the liquid inlet channel, and an injection port being provided at one end of the injection channel away from the liquid inlet channel;

[0067] A stirring rod is inserted into the injection channel, the stirring rod is coaxially arranged with the injection channel, the stirring rod is connected to the first light source emitter, the end of the stirring rod faces the injection port, and the stirring rod includes a rod body with a light-transmitting structure.

[0068] According to one embodiment of the present disclosure, the liquid adding assembly is provided with a plurality of liquid adding chambers, the droplet nozzle is provided with a plurality of liquid inlets, the liquid adding chambers and the liquid inlets correspond one to one, the outer wall of the stirring rod is provided with a guide groove, and the guide groove is wound around the stirring rod multiple times.

[0069] According to an embodiment of the present disclosure, the device further includes: a blocking component connected to the supporting component, wherein the liquid receiving pan of the blocking component moves between an initial position for avoiding the first light and a blocking position for blocking the first light.

[0070] According to one embodiment of the present disclosure, a trigger component is further included, and the blocking component is communicatively connected to the trigger component. Based on the trigger component receiving the trigger signal of the liquid droplet passing through reaching a set number of times, the liquid receiving tray is controlled to switch from the initial position to the blocking position.

[0071] According to one embodiment of the present disclosure, the trigger component includes a second light source emitter and a light intensity sensor, the light intensity sensor is used to receive the light signal of the second light emitted by the second light source emitter, the second light source emitter and the light intensity sensor are respectively arranged on both sides of the first light, and the light emission direction of the second light source emitter intersects with the light emission direction of the first light source emitter.

[0072] According to one embodiment of the present disclosure, the blocking component also includes a rotating console, and a driving device is provided in the shell of the rotating console. The output shaft of the driving device is connected to the liquid receiving pan through a cantilever, and the output shaft rotates to drive the liquid receiving pan to rotate between the initial position and the blocking position.

[0073] According to one embodiment of the present disclosure, the acquisition component includes a high-speed camera and a third light source emitter that provides a background light source for the high-speed camera. The high-speed camera and the third light source emitter are respectively arranged on both sides of the stage. The bottom of the high-speed camera is connected to a three-axis translation stage, and the three-axis translation stage is communicatively connected to the light spot sensor. The three-axis translation stage adjusts the position of the high-speed camera in the horizontal, horizontal longitudinal and vertical directions so that the high-speed camera is aligned with the acquisition position.

[0074] According to an embodiment of the present disclosure, the bottom of the light spot sensor is rotatably connected to a plurality of adjustment columns, and the plurality of adjustment columns are used to adjust the angle between the light spot sensor and the surface of the stage.

[0075] The above one or more technical solutions in the embodiments of the present disclosure have at least one of the following technical effects:

[0076] (1) The method for measuring the flow properties of a liquid provided by the present disclosure determines the calculated viscosity of the droplet based on a first calculation coefficient, the droplet density, the maximum radius of the tip, and the initial height of the tip. The first calculation coefficient is the ratio of the tip height change value to the test duration. The droplet tip height changes with the test duration. The present disclosure can measure the calculated viscosity of the droplet based on the change in the droplet tip height over time. This method is significantly different from existing titration methods, rotation methods, vibration methods, and pipeline methods. The present disclosure can monitor the changes in the droplet in real time, thereby capturing the dynamic changes in the droplet flow properties.

[0077] (2) The droplet observation device provided by the embodiment of the present disclosure has a droplet injection component for generating droplets. The droplet injection component is provided with a first light source emitter. The luminous direction of the first light emitted by the first light source emitter is the direction of the droplet falling, which can accurately locate the droplet falling path and the predetermined position of the droplet falling on the light spot sensor, ensuring that the droplet can accurately fall on the predetermined position. At the same time, the light spot sensor is connected to the collection component for communication. The first light is irradiated on the light spot sensor. The light spot sensor receives the position signal from the first light. The collection component moves to the collection position that matches the position signal. The collection position is the predetermined position of the droplet falling, so that the collection component can accurately locate the collection position and collect images of the entire process of the droplet falling on the light spot sensor.

[0078] In addition to the technical problems solved by the present disclosure, the technical features of the technical solutions constituted, and the advantages brought about by the technical solutions with these technical features described above, other technical features of the present disclosure and the advantages brought about by these technical features will be further explained in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0079] In order to more clearly illustrate the technical solutions in the present disclosure or the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0080] FIG1 is a schematic flow chart of a method for measuring liquid flow properties provided by an embodiment of the present disclosure;

[0081] FIG2 is a schematic diagram of a process for determining the viscosity of a droplet based on a Weber number being greater than or equal to a set threshold according to an embodiment of the present disclosure;

[0082] FIG3 is a schematic diagram of a process for determining a total duration T according to an embodiment of the present disclosure;

[0083] FIG4 is a schematic diagram of a process for determining a droplet surface tension coefficient based on a Weber number being greater than or equal to a set threshold according to an embodiment of the present disclosure;

[0084] FIG5 is a schematic diagram of a structure of a liquid droplet just dropped on a substrate according to an embodiment of the present disclosure;

[0085] FIG6 is a schematic structural diagram of liquid dripping from a needle outlet onto a substrate according to an embodiment of the present disclosure;

[0086] FIG7 is a schematic diagram of the structure of a liquid droplet from the moment it lands on a substrate to the moment it forms a spherical crown, provided by an embodiment of the present disclosure;

[0087] FIG8 is a schematic diagram of obtaining a first calculation coefficient by linearly fitting experimental data according to an embodiment of the present disclosure;

[0088] FIG9 is a schematic diagram of obtaining a second calculation coefficient by linearly fitting experimental data according to an embodiment of the present disclosure.

[0089] FIG10 is a schematic diagram of a structure for observing droplets provided by an embodiment of the present disclosure;

[0090] FIG11 is a schematic structural diagram of a liquid droplet injection component provided in an embodiment of the present disclosure.

[0091] Reference numerals: 100, droplet injection component; 110, first light source emitter; 120, droplet nozzle; 121, liquid inlet; 1211, liquid inlet channel; 1212, liquid inlet; 122, ejection component; 1221, ejection channel; 1222, ejection port; 130, liquid adding assembly; 131, outlet; 132, liquid adding chamber; 140, stirring rod; 141, guide groove; 151, syringe pump; 152, syringe pump controller; 160, bolt; 170, push rod; 200, support component; 210, stage; 220, spot sensor; 221, adjustment column; 300, acquisition component; 310, high-speed camera; 311, zoom lens; 320, third light source emitter; 330, three-axis translation stage; 400, blocking component; 410, liquid receiving pan; 420, rotating control console; 430, output shaft; 440, cantilever; 500, triggering component; 510, second light source emitter; 520, light intensity sensor; 600, moving platform; 700, box. DETAILED DESCRIPTION

[0092] To make the objectives, technical solutions, and advantages of this disclosure more clear, the technical solutions of this disclosure will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of this disclosure, not all of them. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments of this disclosure without creative effort shall fall within the scope of protection of this disclosure.

[0093] In the description of the embodiments of the present disclosure, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as limiting the embodiments of the present disclosure. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance.

[0094] In the description of the embodiments of the present disclosure, it should be noted that, unless otherwise expressly specified or limited, the terms "connected" and "connection" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections; and direct connections or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of the present disclosure.

[0095] In the embodiments of the present disclosure, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, a first feature being "above," "above," and "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is at a higher level than the second feature. A first feature being "below," "below," and "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0096] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiments of the present disclosure. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification and features of different embodiments or examples, unless they are contradictory.

[0097] The method for measuring the flow properties of liquid according to an embodiment of the present disclosure will be described below with reference to FIG. 1 to FIG. 9 .

[0098] As shown in FIG1 , an embodiment of the present disclosure provides a method for measuring the flow properties of a liquid, including steps 110 to 130 .

[0099] Step 110: Control the liquid droplets to drip onto the substrate from a preset height.

[0100] When a droplet falls freely from a predetermined height under the influence of gravity and surface tension, it drags a tip, as shown in Figure 5. When the droplet strikes the substrate, that is, after impact, the tip gradually retracts over time until the droplet assumes a spherical crown shape (see Figure 7). During this process, the tip's retraction is influenced by four forces: inertia, viscosity, surface tension, and gravity.

[0101] The ratio of the gravity on the droplet tip to the surface tension can be expressed by the Bond number (Bo), that is, where ρ is the droplet density, g is the acceleration due to gravity, and R n is the maximum radius of the droplet tip, and γ is the surface tension of the droplet. In the embodiment of the present disclosure, ρ is approximately 1000 kg / m 3 , g is roughly 10m / s 2 , R n Roughly 10 -4 m,γ is roughly 10 -2 N / m, so Bo is approximately 0.01, which means that the effect of gravity on the tip is much smaller than the surface tension. It should be noted that "approximately" means approximately or roughly equal, which can be equal or close.

[0102] Therefore, in the embodiment of the present disclosure, there is no need to consider the effect of gravity on the retraction of the tip.

[0103] Step 120: Obtain the droplet density ρ and the maximum tip radius R on the substrate. n , real-time height of the tip H max , the initial height of the tip H0 and the test time t from the beginning of the droplet landing on the substrate to the end of the measurement.

[0104] Step 130: Determine that the factors affecting the tip of the droplet include inertial force and viscous force, and the inertial force is equal to the viscous force, and calculate the calculated viscosity η of the droplet. The calculated viscosity η of the droplet is related to the first calculation coefficient C1, the droplet density ρ, and the maximum radius of the tip R. n And the initial height H0 of the tip is related to the first calculation coefficient C1, which is equal to the tip height change value ΔH max The ratio of the tip height change ΔH to the test time t; max The initial height H0 of the tip and the real-time height H of the tip max The difference.

[0105] The viscosity is calculated as In this embodiment, the first calculation coefficient C1 is introduced. The present disclosure obtains C1 by measuring the change in droplet tip height over time after the droplet hits the substrate. The time for a single measurement can be less than 0.5s, which can quickly measure the change in droplet viscosity over time and then calculate the calculated viscosity η.

[0106] The method for measuring liquid flow properties provided by the present disclosure determines the calculated viscosity of a droplet based on a first calculation coefficient, droplet density, maximum tip radius, and initial tip height. The first calculation coefficient is the ratio of the tip height change to the test duration. The droplet tip height varies with the test duration. The present disclosure can measure the calculated viscosity of a droplet based on the change in droplet tip height over time. This method, significantly different from existing titration, rotational, vibration, and pipeline methods, can monitor changes in droplets in real time, thereby capturing dynamic changes in droplet flow properties.

[0107] It can be understood that, in conjunction with FIG. 2 , before step 130 , that is, before the step of calculating the viscosity η of the droplet, steps 210 and 220 are also included.

[0108] Step 210: Control the Weber number We of the droplet to be greater than or equal to a set threshold.

[0109] The Weber number is used to compare the effects of inertial force and surface tension. The calculation formula for the Weber number is:

[0110] Among them, W e is the Weber number;

[0111] ρ is the droplet density;

[0112] v0 is the dripping velocity of the droplet when it just lands on the substrate;

[0113] V0 is the droplet volume with the maximum radius of the tip;

[0114] γ is the surface tension coefficient, which represents the surface tension per unit length of a straight line segment on the liquid surface;

[0115] The droplet velocity v0 and droplet volume V0 are obtained when the droplet first lands on the substrate. By controlling the droplet velocity v0 and droplet volume V0, the numerical range of the Weber number is adjusted. The Weber number can be adjusted between 1 and 500.

[0116] Step 220: Based on the Weber number We being greater than or equal to a set threshold, determine that the factors affecting the tip of the droplet include inertial force and viscous force, and the inertial force is equal to the viscous force.

[0117] In the embodiment of the present disclosure, let the threshold be set to 100. When the Weber number is greater than or equal to 100, the tip of the droplet is dominated by both inertial force and viscous force, and the two are balanced, that is, the inertial force is equal to the viscous force:

[0118] Where ρ is the droplet density;

[0119] η is the calculated viscosity;

[0120] R n is the maximum radius of the tip;

[0121] t is the test time from the beginning of the droplet falling on the substrate to the end of the test. When t = 0, the droplet has just dripped onto the substrate, that is, the droplet hits the substrate;

[0122] H max is the real-time height of the tip, which changes with the test duration t;

[0123] It should be noted that: Indicates H max The second-order partial derivative operation with respect to t is: Indicates H max Computes the first-order partial derivative with respect to t.

[0124] Solving formula (1) yields:

[0125] From formula (2), we can get:

[0126] Where ΔH max is the tip height change, ΔH max =H0-H max ;

[0127] H0 is the initial height of the tip when the droplet lands on the substrate;

[0128] C1 is the first calculation coefficient, where

[0129] Regarding the Weber number being greater than or equal to 100, it should be noted that: in some embodiments, the preset height is greater than or equal to 11.8 cm, and the maximum radius of the tip R n The preset height can affect the droplet's dripping speed v0 when it just lands on the substrate, that is, the preset height can affect the speed of the droplet when it hits the substrate. In this embodiment, by making the preset height greater than or equal to 11.8 cm, the maximum radius R of the tip is nBetween 0.5mm and 1mm, the requirement of We>100 can be guaranteed, and the factors affecting the force on the tip of the droplet include inertial force and viscous force, thereby avoiding the influence of surface tension when measuring the viscosity of the droplet.

[0130] It should be noted that, in conjunction with FIG. 3 , step 110 , ie, the step of controlling the droplet to drip onto the substrate from a preset height, further includes steps 310 to 330 .

[0131] Step 310: Obtain the flow time T1 of the droplet flowing in the container; wherein the container is used to contain liquid, and the liquid forms droplets at the opening of the container.

[0132] The container can be a needle tube, and the liquid can enter the needle tube from the inlet and flow in the needle tube. The liquid flows to the outlet of the needle tube, and when the droplets are affected by gravity and surface tension, they will drip from the outlet. It can be understood that the time it takes for the liquid to flow from the inlet of the needle tube to the outlet is the flow time T1. In conjunction with Figure 6, the maximum radius R of the tip at this time is n The radius of the tip is equal to the radius of the needle outlet, that is, the maximum radius R n Depends on the radius of the needle outlet. Of course, the container is not limited to the needle tube, it can also be a test tube or other customized container. By adjusting the radius of the container outlet, the maximum radius R of the tip can be adjusted. n .

[0133] In related technologies, taking the rotation method for measuring the flow properties of droplets as an example, it is necessary to place the measured droplets on the measuring device and rotate them until the droplets solidify. The solidification of the droplets may make it difficult to clean the solidified droplets, thereby causing the measuring device to fail.

[0134] In the disclosed embodiments, it is understood that the droplets are not completely solidified while the liquid is in the container, while the droplets are dripping, and while the droplets are being measured. In other words, the droplets are not completely solidified during the entire measurement process. Droplets can transition from a flowing state to a completely solidified state. In this embodiment, the droplets remain in a partially solidified state throughout the measurement process, thereby avoiding measurement device failure due to droplet solidification.

[0135] Step 320: Obtain the dripping time T2 from the start of the droplet dripping to the droplet landing on the substrate.

[0136] In the embodiments of the present disclosure, the dripping duration T2 can be controlled by controlling the preset height. That is, the reaction time (dripping duration T2) of the liquid droplet when it reaches the substrate can be controlled by controlling the falling height of the liquid droplet. It can be understood that taking a syringe containing liquid and the liquid being synthesized from multiple substances as an example, such as: the liquid is a binder, and the binder needs various additives to meet the requirements of different applications. Multiple substances can be mixed in the syringe to synthesize the liquid, then it can be understood that the liquid synthesis is achieved in the syringe. Compared with the related art where the synthesized liquid needs to be statically placed, pumped, and finally measured in sequence, this embodiment can achieve the integration of liquid synthesis, transportation, and measurement. It can not only effectively save time. After synthesis, there is no need to wait for static placement or pumping. By controlling the falling height of the liquid droplet, the next step (transportation) can be achieved, and then measurement can be achieved, thereby improving the experimental efficiency. Among them, the process from when the liquid droplet starts to drip to when it lands on the substrate is transportation.

[0137] Step 330: Determine that the sum of the flowing duration T1, the dripping duration T2, and the testing duration t is the total duration T, and the testing duration t is much smaller than the total duration T.

[0138] In the embodiments of the present disclosure, the total duration T = T1 + T2 + t. Among them, the testing duration t can be understood as the time after the liquid droplet impacts the substrate, and the total duration T can be understood as the reaction time of the liquid droplet. Regarding the reaction time, it should be noted that taking the liquid droplet as resin or binder as an example, resin and binder are usually liquid or semi-solid materials and require a certain amount of time to harden, cure, or bond. The reaction time of the liquid droplet can be understood as the time required for the liquid droplet to cure or harden.

[0139] Among them, the viscosity of the liquid on the substrate is a function of T, that is, η = f(T). In this embodiment, when the testing duration t is much smaller than the total duration T, that is, t << T, for example: t = 0.01 s, T = 0.5 s; t = 0.02 s, T = 0.4 s. In the embodiments of the present disclosure, since t << T, the viscosity change of the liquid droplet within the time t can be ignored. Because t is small enough, the viscosity change of the liquid droplet itself when dripping affected by the blockage of the substrate during the measurement process can be ignored. Thus, the viscosity of the liquid droplet after the total duration T can be characterized by the change value ΔH of the tip height of the liquid droplet on the substrate max and the testing duration t, that is:

[0140] Thus, the method for measuring liquid flow properties in this embodiment can measure changes in the flow properties (e.g., viscosity and surface tension) of a droplet after different reaction times by controlling the total reaction time (reaction time) T. Since the test time t is much shorter than the total reaction time T, the effect of changes in the droplet viscosity during the test time t can be avoided and the changes in the droplet viscosity during the test time t can be ignored. The droplet flow properties for the total reaction time T can be calculated based on the test time. Furthermore, since the test time is sufficiently short, the measurement time can be effectively reduced, enabling rapid detection of droplet flow properties.

[0141] The above describes how to determine the viscosity of a liquid droplet. The following describes how to determine the surface tension coefficient of a liquid droplet.

[0142] 4 , in this embodiment, the method for measuring the flow properties of a liquid further includes steps 410 to 440 .

[0143] Step 410: Control the Weber number W of the droplet e Less than the set threshold.

[0144] Step 420: Based on the Weber number W e When the tip is smaller than the set threshold, the factors affecting the tip include viscous force and surface tension, and the viscous force is equal to the surface tension.

[0145] After calculating the droplet viscosity η in step 430, the tip height change ΔH is determined based on the fact that the viscous force is equal to the surface tension. max The ratio of the cube of to the test duration t is the second calculation coefficient C2.

[0146] Step 440: Calculate the viscosity η, the second calculation coefficient C2 and the maximum radius R of the tip. n Calculate the surface tension coefficient γ of the surface tension.

[0147] In the embodiment of the present disclosure, let the threshold be set to 100. When the Weber number is less than 100, the tip of the droplet is dominated by both surface tension and viscous force, and the two are balanced, that is, the surface tension is equal to the viscous force:

[0148] Where ΔH max is the tip height change, ΔH max =H0-H max ; H0 is the initial height of the tip when the droplet lands on the substrate; H max is the real-time height of the tip, which changes with the test duration t;

[0149] Rn is the maximum radius of the tip;

[0150] η is the calculated viscosity;

[0151] t is the test duration from the beginning of landing on the base to the end of the test;

[0152] Surface tension is F = γR n ;

[0153] γ is the surface tension coefficient, which represents the surface tension per unit length of a straight line segment on the liquid surface;

[0154] Solving formula (3) yields:

[0155] From formula (4), we can get:

[0156] Among them, C2 is the second calculation coefficient, where,

[0157] In this embodiment, the second calculation coefficient C2 is introduced. In this embodiment, based on W e >100, at this time, the force acting on the droplet tip is dominated by inertial force and viscous force, so under the condition of avoiding the influence of surface tension on the droplet tip, the change of the droplet tip height over time after the droplet hits the substrate is measured to obtain C1, and then the viscosity η is calculated; further, W is controlled e <100, at this time, the force acting on the droplet tip is dominated by viscous force and surface tension. By measuring the change of the droplet tip height over time after the droplet hits the substrate, C2 is obtained. Finally, the calculated viscosity η is substituted into formula (5) to obtain the surface tension coefficient γ.

[0158] The method for measuring the flow properties of a liquid provided in the embodiment of the present disclosure measures and determines the first calculation coefficient C1 and the second calculation coefficient C2 based on the change in the droplet tip height over time, and then determines the calculated viscosity η and the surface tension coefficient γ. It can not only monitor the changes in the droplet in real time and capture the dynamic changes in the droplet flow properties, but also accurately measure the changes in the viscosity and surface tension of the droplet during the entire solidification process.

[0159] At the same time, this embodiment can use the same set of equipment to measure the viscosity and surface tension of the droplet over time, making data calculation and analysis more convenient. There is no need to use different equipment to measure different parameters, which can save time and resources and ensure the consistency of the experiment.

[0160] It should be noted that the calculated viscosity η can be substituted into formula (5) to obtain the surface tension coefficient γ. Assuming that the total time for measuring the calculated viscosity η is Tη and the total time for measuring the surface tension coefficient γ is Tγ, it is necessary to ensure that Tη=Tγ before the calculated viscosity η can be substituted into formula (5) to obtain the surface tension coefficient γ.

[0161] The first calculation coefficient C1 will be described with reference to FIG8 .

[0162] In step 130, the tip height change value ΔH is determined. max The ratio of the tip height H0 to the test time t is the first calculation coefficient C1, and the tip initial height H0 and multiple tip real-time heights H within the test time t are obtained. max , the first calculation coefficient C1, the test time t and the tip height difference ΔH are obtained by fitting max linear relationship.

[0163] After the droplet hits the substrate, the tip height H max It will change with the test time, through multiple tip height change values ​​ΔH max The experimental data and the corresponding test time t are linearly fitted to obtain the slope C1, which is the first calculation coefficient. This quantifies the experimental data and provides a numerical parameter (slope C1) to provide a reliable basis for the subsequent calculation of the viscosity η.

[0164] Similarly, in conjunction with Figure 9, when determining the tip height change value ΔH max In the step where the ratio of the cube of the tip to the test time t is the second calculation coefficient C2, the tip initial height H0 and multiple tip real-time heights H within the test time t are obtained. max , the second calculation coefficient C2, the test time t and the tip height difference ΔH are obtained by fitting max By linearly fitting the experimental data and obtaining the slope C2, which is the second calculation coefficient, the experimental data is quantified and a numerical parameter (slope C2) is provided to provide a reliable basis for the subsequent calculation of the surface tension coefficient γ.

[0165] Next, the outflow measurement of the method for measuring the flow properties of liquid provided by the embodiment of the present disclosure is described.

[0166] (1) To obtain the calculated viscosity η of the liquid after a period of time T, it is necessary to calculate the time the droplet flows in the needle (flowing time) T1 and the time the droplet falls in the air (dripping time) T2, and ensure that the droplet velocity at impact (drop velocity v0 when the droplet just lands on the substrate) and the droplet volume (drop volume V0) meet the requirement of We>100. In this method, the recommended drop height should be greater than 11.8 cm, and the needle radius (maximum tip radius R n ) is between 0.5mm and 1mm.

[0167] (2) Combined with Figure 8, the change in the droplet tip height over time was recorded after the droplet hit the substrate, and the experimental data were linearly fitted to obtain the slope C1.

[0168] (3) Using the formula Calculate the calculated viscosity η.

[0169] (4) To determine the surface tension of the liquid after a time T, it is necessary to calculate the time the droplet flows in the needle, T1, and the time the droplet falls in the air, T2, and ensure that the velocity of the droplet at impact and the radius of the needle meet the requirement of We < 100. In this method, the recommended drop height should be less than 8 cm and the needle radius should be between 0.5 mm and 1 mm.

[0170] (5) Combined with Figure 9, the change in the droplet tip height over time after the droplet hits the substrate is recorded, and ΔH is plotted. max 3 The curve of vs. t was linearly fitted to the experimental data and the slope C2 was obtained.

[0171] (6) Using the formula To calculate the surface tension coefficient γ.

[0172] Next, the device for observing droplets according to the second embodiment of the present disclosure will be described with reference to FIG10 and FIG11 .

[0173] As shown in Figure 10, the device for observing droplets provided by the embodiment of the present disclosure includes: a droplet injection component 100, a support component 200, and a collection component 300. The droplet injection component 100 is used to generate droplets. The droplet injection component 100 includes a first light source emitter 110. The dripping direction of the droplet is the same as the emitting direction of the first light emitted by the first light source emitter 110; one end of the support component 200 is connected to the droplet injection component 100, and the other end of the support component 200 is connected to the stage 210, and the stage 210 is used to support the spot sensor 220; the collection component 300 is used to obtain an image of the droplet falling on the spot sensor 220, and the collection component 300 is communicatively connected to the spot sensor 220; based on the position signal of the first light received by the spot sensor 220, the collection component 300 is controlled to move to the collection position matching the position signal.

[0174] The present embodiment provides a device for observing droplets. The droplet injection component 100 is used to generate droplets. The droplet injection component is provided with a first light source emitter 110. The direction of the first light emitted by the first light source emitter 110 is the direction of the droplet's landing. It can accurately locate the droplet's landing path and the predetermined position of the droplet on the light spot sensor 220, ensuring that the droplet can accurately land at the predetermined position. At the same time, the light spot sensor 220 is in communication with the collection component 300. The first light is irradiated on the light spot sensor 220. The light spot sensor 220 receives the position signal from the first light. The collection component 300 moves to the collection position that matches the position signal. The collection position is the predetermined position where the droplet falls, so that the collection component 300 can accurately locate the collection position and collect images of the entire process of the droplet landing on the light spot sensor 220.

[0175] In some other embodiments, the device for observing droplets also includes a moving platform 600, and the droplet injection component 100 is connected to the support component 200 through the moving platform 600. The mobile platform 600 can move along the height direction of the support component 200 to adjust the distance between the droplet injection component 100 and the light spot sensor 220, thereby adjusting the height of the droplet falling to meet experiments with different requirements for the droplet falling height.

[0176] The droplet injection component 100 includes a droplet nozzle 120 and a liquid adding component 130. The outlet 131 of the liquid adding component 130 is directed toward the liquid inlet 1212 at one end of the droplet nozzle 120. A jet outlet 1222 is provided at the other end of the droplet nozzle 120. The first light source emitter 110 is connected to the droplet nozzle 120 and is coaxially arranged with the jet outlet 1222 so that the first light is emitted from the jet outlet 1222. It can be understood that droplets will be sprayed out and dripped from the injection port 1222. The light emitting direction of the first light source emitter 110 passes through the injection port 1222 and is emitted from the injection port 1222 to form a light path. The droplet dripping direction is the same as the light emitting direction of the first light emitted by the first light source emitter 110, that is, the droplet will move along the light path of the first light source, and the light emitting direction of the first light source emitter 110 is used to indicate the landing point of the droplet. Not only can the landing point of the droplet injection be observed in real time, but the landing position of the droplet can also be accurately located, so as to timely monitor and adjust the path and landing point of the droplet injection.

[0177] Among them, the coaxial setting ensures the accurate alignment between the position of the first light and the injection port 1222, avoids the inner wall of the droplet nozzle 120 from blocking the first light, helps to accurately control the emission direction of the first light through the injection port 1222, and ensures that the first light is irradiated along the desired path.

[0178] In some embodiments, the light spot sensor 220 is connected to a protective layer, which is connected above the light spot sensor 220. The protective layer is a layer with a light-transmitting structure. The protective layer can not only protect the light spot sensor 220 and prevent the reaction droplets from contaminating the light spot sensor 220, but also allow the first light to pass through and illuminate the light spot sensor 220, thereby ensuring the normal use of the light spot sensor 220.

[0179] The protective layer can be glass, quartz, or a light-transmitting film structure, and the protective layer can be selected according to actual needs.

[0180] The structure of the droplet spray head 120 will be described below with reference to FIG. 11 .

[0181] As shown in Reference Figure 11, the droplet nozzle 120 includes: a liquid inlet portion 121, an ejection portion 122 and a stirring rod 140, the liquid inlet portion 121 forms a liquid inlet channel 1211, and a liquid inlet port 1212 is set at one end of the liquid inlet channel 1211; the ejection portion 122 forms an ejection channel 1221, the ejection portion 122 is connected to the liquid inlet portion 121, the ejection channel 1221 is connected to the other end of the liquid inlet channel 1211, and an ejection port 1222 is set at an end of the ejection channel 1221 away from the liquid inlet channel 1211; the stirring rod 140 is inserted into the ejection channel 1221, the stirring rod 140 is coaxially arranged with the ejection channel 1221, the stirring rod 140 is connected to the first light source emitter 110, the end of the stirring rod 140 faces the ejection port 1222, and the stirring rod 140 includes a rod body with a light-transmitting structure.

[0182] In the embodiment of the present disclosure, a stirring rod 140 is provided in the droplet nozzle 120. The stirring rod 140 is inserted into the injection channel 1221 and can stir the liquid in the droplet nozzle 120. When the liquid is a high viscosity, non-Newtonian fluid or a reactive liquid, the stirring of the stirring rod 140 can improve its fluidity, stabilize the liquid flow, ensure the stability of the droplets dripping from the injection port 1222, and avoid blockage of the droplet nozzle 120.

[0183] It should be noted that the reaction liquid (which can also be understood as reaction droplets) can be understood as a liquid (droplet) that can undergo a chemical reaction itself or react chemically with the surrounding environment, such as epoxy resin, 502 glue, etc.

[0184] 10 , the first light source emitter 110 is disposed at one end of the stirring rod 140. Furthermore, the first light source emitter 110 is disposed outside the ejection portion 122, thereby preventing liquid from entering the first light source emitter 110 and affecting the first light source emitter 110. The stirring rod 140 includes a light-transmitting rod body, which ensures that light from the first light source emitter 110 passes through the transmission shaft, reducing light obstruction by the stirring rod 140 and thereby improving positioning accuracy.

[0185] Of course, the first light source emitter 110 can also be disposed within the stirring rod 140. In this case, the stirring rod 140 is a light-transmitting structure, and a cavity for mounting the first light source emitter 110 is formed within the stirring rod 140. This eliminates the need for additional mounting space for the first light source emitter 110, resulting in a compact structure and reduced volume. The first light source emitter 110 can also be disposed at the bottom of the stirring rod 140, with the first light source emitter 110 being sealedly connected to the stirring rod 140 via a connector to prevent interference caused by liquid entering the first light source emitter 110. The arrangement of the first light source emitter 110 can be configured according to actual needs and is not limited here. The connection of the first light source emitter 110 to the stirring rod 140 can reduce interference with light from external environmental factors, thereby improving the stability and repeatability of the experiment. At the same time, the emission direction of the first light from the first light source emitter 110 passes through the stirring rod 140. That is, this embodiment integrates the optical path into the stirring rod 140, which can reduce the complexity of the optical path of the first light source, reduce light loss, improve the transmission efficiency of the first light source, and improve the positioning effect of the droplet.

[0186] The liquid adding assembly 130 is provided with multiple liquid adding chambers 132, and the droplet spray head 120 is provided with multiple liquid inlets 1212, with each liquid adding chamber 132 corresponding to the liquid inlet 1212. The droplet spray head 120 is provided with multiple liquid inlets 1212, that is, multiple liquid inlet channels 1211 are provided, and the multiple liquid inlet channels 1211 are connected to the injection channel 1221. When the liquid components in the multiple liquid inlet channels 1211 are different, that is, the liquid in the injection channel 1221 is a synthetic liquid formed by mixing multiple liquids of different components, the stirring paddle inserted in the injection channel 1221 can fully mix the liquids of different components, thereby improving the quality of the synthetic liquid in the injection channel 1221. For example, some special resins or synthetic solvents can place liquids of different components (such as resins, hardeners, diluents, etc.) in multiple liquid inlet channels 1211. After the liquids of multiple components are fully stirred and mixed by the stirring rod 140, they enter the injection channel 1221. During the mixing process, the liquids of multiple components undergo chemical reactions to form special resins or synthetic solvents.

[0187] The one-to-one correspondence between the liquid adding cavity 132 and the liquid inlet 1212 can effectively prevent cross contamination between liquids of different components and maintain the purity of the sample and the accuracy of the experiment.

[0188] It should be noted that when the liquid nozzle includes multiple liquid inlet channels 1211, the liquid components in the multiple liquid inlet channels 1211 can be different, the same, or some can be the same and some different. The liquid components in the multiple liquid inlet channels 1211 can be selected according to actual needs.

[0189] In conjunction with Figure 10, the outer wall of the stirring rod 140 is provided with a guide groove 141, and the guide groove 141 is wound around the stirring rod 140 for multiple turns. When the liquid flows from the liquid inlet channel 1211 to the injection channel 1221, the droplets flow along the guide groove 141, so that the stirring rod 140 can achieve the stirring of the liquid. A plurality of liquid inlet channels 1211 are provided in the droplet nozzle 120. When the components of the liquid in the plurality of liquid inlet channels 1211 are different, the liquids with different components are mixed while flowing along the guide groove 141, thereby achieving the generation of the synthetic liquid in the injection channel 1221. At the same time, the guide groove 141 is wound around the stirring rod 140 for multiple turns, so that the stirring and mixing are more uniform, which helps to ensure the uniformity of the reaction or mixing process. The synthesis of the reaction liquid can be achieved while the liquid flows to the injection port 1222, without having to wait for the liquid to be synthesized before entering the droplet nozzle 120, saving experimental time and improving experimental efficiency.

[0190] The droplet nozzle 120 is provided with multiple liquid inlets 1212, that is, multiple liquid inlet channels 1211 are provided, and multiple liquid inlet channels 1211 are connected to the injection channel 1221. The liquid components in the multiple liquid inlet channels 1211 can be different, or the same, or some can be the same and some different. The liquid components in the multiple liquid inlet channels 1211 can be selected according to actual needs.

[0191] The stirring rod 140 may be a threaded rod, and the guide groove 141 may be a threaded rod. The stirring rod 140 has a simple structure and can effectively stir and mix the liquid. By adjusting the size, spacing, and number of turns of the threads, that is, by adjusting the size, spacing, and number of turns of the guide groove 141, the speed and degree of liquid stirring and mixing can be adjusted. The guide groove 141 can be set according to actual needs.

[0192] In some other embodiments, a baffle is provided in the liquid inlet channel 1211, with one end of the baffle connected to the liquid inlet portion 121 and the other end of the baffle tilted downward to effectively prevent liquid backflow. The other end of the baffle forms a liquid inlet with the inner wall of the liquid inlet portion 121. The baffle not only prevents liquid backflow but also ensures that liquid can enter through the liquid inlet, effectively ensuring liquid input and thus ensuring the stability of liquid flow.

[0193] The device for observing droplets also includes a blocking member 400, which is connected to the support member 200. The liquid receiving pan 410 of the blocking member 400 can move between an initial position that avoids the first light and a blocking position that blocks the first light. When the liquid receiving pan 410 is in the initial position, the liquid receiving pan 410 avoids the first light. At this time, the liquid receiving pan 410 avoids the droplets, and the droplets drip onto the spot sensor 220 unimpeded along the emission direction of the first light. When the liquid receiving pan 410 is in the blocking position, it can be understood that the liquid receiving pan 410 is located between the first light source emitter 110 and the spot sensor 220, and the liquid receiving pan 410 blocks the first light. At this time, the first light is irradiated on the liquid receiving pan 410, and the first light is not irradiated on the spot sensor 220. The droplets will drip onto the liquid receiving pan 410, thereby preventing subsequent droplets from dripping onto the spot sensor 220 and affecting the collision experiment of the previous droplets on the spot sensor 220.

[0194] The device for observing droplets also includes a trigger component 500. The blocking component 400 is communicatively connected to the trigger component 500. Upon receiving a predetermined number of trigger signals indicating a droplet has passed through, the trigger component 500 controls the liquid receiving tray 410 to switch from its initial position to a blocking position. It is understood that each time a droplet falls, the trigger component 500 triggers a trigger signal, and each trigger signal from the trigger component 500 indicates that the droplet has fallen once. When the predetermined number of droplets has fallen, the liquid receiving tray 410 is controlled to switch from its initial position to a blocking position to prevent subsequent droplets from affecting previous droplets.

[0195] Taking the setting number of times as one as an example, when a droplet falls once (assuming that the droplet falling at this time is droplet A), the trigger component 500 is triggered once, and the trigger component 500 generates a trigger signal, which controls the liquid receiving plate 410 to switch from the initial position to the blocking position. At this time, droplet A has passed the blocking position of the liquid receiving plate 410, and droplet A will continue to move downward until it drops on the light spot sensor 220. At the same time, the liquid receiving plate 410 moves to the blocking position, which can prevent subsequent droplets from dripping on the light spot sensor 220 and affecting droplet A.

[0196] Of course, the set number of times is not limited to one, and can also be two, that is, the droplet passes through the trigger component 500 twice before controlling the liquid receiving tray 410 to switch from the initial position to the shielding position. The set number of times can also be three, four, etc., and the set number of times can be selected according to actual needs.

[0197] The trigger component 500 includes a second light source emitter 510 and a light intensity sensor 520. The light intensity sensor 520 is used to receive the optical signal of the second light emitted by the second light source emitter 510. The second light source emitter 510 and the light intensity sensor 520 are respectively arranged on both sides of the first light, and the light emission direction of the second light source emitter 510 intersects with the light emission direction of the first light source emitter 110. Among them, the light intensity sensor 520 is used to receive the optical signal of the second light emitted by the second light source emitter 510 and output a trigger signal when the optical signal changes. When a droplet falls through the second light, the area of ​​the droplet blocking the second light will change from small to large and then to small. Correspondingly, the light intensity on the surface of the light intensity sensor 520 (i.e., the optical signal of the second light) changes from strong to weak and then to strong. At this time, the light intensity sensor 520 sends a trigger signal. The light intensity sensor 520 receives a weak light signal once and then sends a trigger signal. It can be understood that the dripping direction of the droplet is the same as the light-emitting direction of the first light source emitter 110, and the light-emitting direction of the second light source emitter 510 intersects with the light-emitting direction of the first light source emitter 110. The positioning of the droplet and the trigger component 500 is simple, and the moving path of the droplet can be accurately located before starting the experiment, ensuring that the droplet passes through the second light, thereby ensuring that the trigger component 500 can accurately detect the number of times the droplet passes, thereby ensuring the experimental effect.

[0198] The blocking component 400 also includes a rotating console 420. A drive device is disposed within the housing of the rotating console 420. The output shaft 430 of the drive device is connected to the liquid receiving pan 410 via a cantilever 440. The output shaft 430 rotates to drive the liquid receiving pan 410 between an initial position and a blocked position. It is understood that the trigger component 500 is in communication with the rotating console 420. After a set number of droplets have passed through, the trigger component 500 sends a trigger signal to the rotating console 420. Upon receiving the trigger signal, the rotating console 420 controls the output shaft 430 of the drive device to rotate, thereby driving the cantilever 440 connected to the output shaft 430 to rotate. The cantilever 440 is connected to the liquid receiving pan 410, thereby driving the liquid receiving pan 410 to rotate from the initial position to the blocked position. Of course, when a droplet experiment is required, the rotating console 420 controls the output shaft 430 to rotate, thereby driving the cantilever 440 to rotate, thereby driving the liquid receiving pan 410 from the blocked position to the initial position. The blocking component 400 has a simple structure, and the rotating console 420 precisely controls the position of the liquid receiving pan 410, enabling accurate rotation between its initial position and its blocking position, thereby ensuring both the avoidance and blocking of the first light beam. Furthermore, locating the drive device within the housing of the rotating console 420 not only saves additional space for the drive device, but also creates a compact blocking assembly and protects the drive device from external environmental factors.

[0199] In some embodiments, the device for observing droplets also includes a moving platform 600, and the blocking component 400 is connected to the supporting component 200 through the moving platform 600. When the moving platform 600 moves along the height direction of the supporting component 200, it can drive the blocking component 400 to move, thereby adjusting the height position of the blocking component 400.

[0200] When the device for observing droplets also includes a moving platform 600, the droplet injection component 100 and the blocking component 400 can also be connected to the support component 200 through the moving platform 600, and the moving platform 600 moves along the height direction of the support component 200 to make the droplet injection component 100 and the blocking component 400 move synchronously.

[0201] The acquisition component 300 includes a high-speed camera 310 and a third light source emitter 320 that provides background light for the high-speed camera 310. The high-speed camera 310 and the third light source emitter 320 are respectively arranged on either side of the stage 210. A three-axis translation stage 330 is connected to the bottom of the high-speed camera 310. The three-axis translation stage 330 is in communication with the spot sensor 220 and adjusts the position of the high-speed camera 310 in the horizontal, vertical, and vertical directions to align the high-speed camera 310 with the acquisition position. The three-axis translation stage 330 is in communication with the spot sensor 220. When the spot sensor 220 receives the light signal from the first light, it locates the light spot position of the first light (i.e., the predetermined location where the droplet landed) and transmits this position signal to the three-axis translation stage 330. The three-axis translation stage 330 controls the high-speed camera 310 to make fine adjustments in the horizontal, vertical, and vertical directions, thereby enabling the high-speed camera 310 to move to the acquisition position aligned with the light spot position. Specifically, the three-axis translation stage 330 can adjust the position of the high-speed camera 310 in the forward, backward, upward, and left-right directions. High-speed camera 310 can make real-time adjustments based on the droplet's landing position, effectively improving experimental flexibility and efficiency. It can also precisely align the light spot position, enhancing the accuracy of droplet image capture.

[0202] The third light source emitter 320 provides a background light source for the high-speed camera 310 . The background light source can reduce shadows and improve the visibility of droplets, effectively improve the quality and clarity of liquid images, and help to better capture images.

[0203] The bottom of the spot sensor 220 is rotatably connected to a plurality of adjustment posts 221, which are used to adjust the angle between the spot sensor 220 and the surface of the stage 210. It is understood that the stage 210 is used to place the spot sensor 220. For example, if the surface of the stage 210 is a horizontal plane, the plurality of adjustment posts 221 are used to support the spot sensor 220. The angle between the spot sensor 220 and the surface of the stage 210, that is, the angle with the horizontal plane, can be adjusted. This allows different experiments to meet the angle requirements of droplets hitting the spot sensor 220 at different angles, thus satisfying experimental needs under different conditions without having to replace or reinstall the spot sensor 220.

[0204] Of course, the angle can be 0 degrees, in which case the surface of the spot sensor 220 is a horizontal plane; or it can be greater than 0 degrees and less than 90 degrees. The angle can be selected according to actual needs.

[0205] Next, the device for observing droplets provided by an embodiment of the present disclosure will be described with reference to FIG10 .

[0206] As shown in FIG10 , a test platform (device for observing droplets) is constructed. The device for observing droplets mainly includes four parts: a droplet injection component 100 , a blocking component 400 , a collection component 300 and a support component 200 .

[0207] The droplet injection assembly 100 comprises a single-channel syringe pump 151, a syringe pump controller 152, a syringe barrel (liquid addition assembly 130), a needle (droplet ejector 120), and a z-axis motorized translation stage (mobile platform 600). The syringe pump 151 is secured to the mobile platform 600 via bolts 160, and a syringe must be mounted on the syringe pump 151.

[0208] The specific structure of the syringe is shown in Figure 11. The syringe includes a needle with a light-transmitting screw (stirring rod 140), a light source device (first light source emitter 110) above the screw, a double-chamber (the chamber is the liquid adding chamber 132) syringe and a push rod 170.

[0209] One end of the light-transmitting screw in contact with the light source device is flat, and the other end is spherical, so that the light emitted by the light source device can pass through the light-transmitting screw and be converged by the spherical cap before being emitted from the tip of the needle to form a light spot on the light spot sensor 220.

[0210] When two different liquids are needed to synthesize droplets, chambers A and B of the syringe are each filled with a different liquid. If the droplets are single-component, the same liquid is held in chambers A and B. Syringe pump 151 squeezes plunger 170, pushing the liquids in the chambers into the needle tip, where they are mixed by the light-transmitting screw.

[0211] The specific design of the blocking component 400 is shown in FIG10 , and its components include a laser (second light source emitter 510 ), a light intensity sensor 520 , a rotating console 420 , a cantilever 440 , and a liquid receiving pan 410 .

[0212] The blocking component 400 and the syringe pump 151 are fixed on the mobile platform 600, and the liquid receiving tray 410 is located below the needle tip. The laser emitted by the laser falls on the light intensity sensor 520, and the laser light path intersects with the light emitted from the needle tip.

[0213] Light intensity sensor 520 acts as a trigger, connected to rotating console 420. It outputs an excitation signal when the light intensity on its surface changes dramatically. Initially, when the laser strikes light intensity sensor 520, there is no change in light intensity. The liquid pan 410 is positioned at a distance from the needle tip (at this point, the liquid pan 410 is in its initial position, out of the direction of the first light beam). This means that the liquid pan 410 does not affect the light emitted from the needle tip and does not affect the light spot sensor 220.

[0214] As a droplet forms and falls from the needle tip, the light intensity on the surface of light intensity sensor 520 decreases from strong to weak and then to strong again, triggering a trigger signal. Once triggered, rotation console 420 controls the drive shaft to rotate a certain angle, driving liquid tray 410 via cantilever 440. This allows the tray to rotate directly below the needle tip, effectively positioning the vertical projection of the needle tip within the tray. This prevents subsequent droplets from reaching light spot sensor 220.

[0215] The other end of support member 200 is connected to stage 210, which supports a light spot sensor 220 covered by a light-transmitting material (e.g., glass). Light spot sensor 220 can determine the position of the light spot of the first light beam falling on the surface (light spot sensor 220 receives a position signal of the first light beam) and send a signal to the three-axis translation stage 330.

[0216] The high-speed imaging mechanism (collection component 300) consists of a high-speed camera 310, a zoom lens 311, a three-axis translation stage 330, and a strong light source (third light source emitter 320). The high-speed camera 310 begins recording images upon receiving a signal from the light intensity sensor 520. The three-axis translation stage 330 begins operating upon receiving a signal from the light spot sensor 220, moving the camera's focal plane to the location of the light spot (that is, controlling the collection component 300 to move to a collection position that matches the position signal).

[0217] The droplet injection component 100 (excluding the injection pump controller 152), the blocking component 400, the stage 210 and the spot sensor 220 are all placed in the transparent box 700 to prevent the air flow from interfering with the observation process.

[0218] Next, the measurement process of the device for observing droplets according to an embodiment of the present disclosure is described.

[0219] (1) The test liquid is loaded into the syringe, and the first light source emitter 110 on the droplet nozzle 120 is turned on, so that the first light emitted by the first light source emitter 110 is irradiated on the light spot sensor;

[0220] (2) Turn on the second light source emitter 510, and the second light emitted by the second light source emitter 510 is projected onto the light intensity sensor 520. At this time, the position of the liquid receiving tray 410 is in the initial position;

[0221] (3) Adjusting the movable platform 600 so that the distance between the ejection port 1222 of the droplet ejection head 120 and the light spot sensor 220 reaches a specified height; wherein, the light spot sensor 220 is covered with a light-transmitting layer, which may be glass. Alternatively, the movable platform 600 is adjusted so that the distance between the ejection port 1222 of the droplet ejection head 120 and the glass substrate (glass light-transmitting layer) reaches a specified height;

[0222] (4) Starting the light spot sensor 220, the third light source emitter 320, the high-speed camera 310, and the three-axis translation stage 330, and moving the high-speed camera 310 to the acquisition position and completing the focusing according to the light spot position on the light spot sensor 220;

[0223] (5) Start the syringe pump 151, which squeezes the syringe push rod 170 to push the liquid in the liquid adding chamber 132 out. The liquid enters the droplet nozzle 120 from the liquid inlet 1212, and finally generates droplets at the injection port 1222 of the droplet nozzle 120 and drips from the needle tip (i.e., the injection port 1222).

[0224] (6) The droplet passes through the second light, triggering the light intensity sensor 520, causing the liquid receiving tray 410 to rotate from the initial position to the shielding position, and the high-speed camera 310 begins to collect images.

[0225] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than to limit them. Although the present disclosure has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present disclosure.

Claims

1. A method for measuring the flow properties of a liquid, comprising: Control the droplets to drip onto the substrate from a preset height; Acquire the droplet density on the substrate, the maximum radius of the tip, the real-time height of the tip, the initial height of the tip, and the test time from when the droplet starts to fall on the substrate to when the measurement ends; Determine that the influencing factors of the tip of the droplet include inertial force and viscous force, and the inertial force is equal to the viscous force, and calculate the calculated viscosity of the droplet. The calculated viscosity of the droplet is related to the first calculation coefficient, the droplet density, the maximum radius of the tip and the initial height of the tip. The first calculation coefficient is equal to the ratio of the tip height change value to the test duration, wherein the tip height change value is the difference between the initial height of the tip and the real-time height of the tip.

2. The method for measuring liquid flow properties according to claim 1, wherein: Before the step of calculating the viscosity of the droplet, Controlling the Weber number of the droplet to be greater than or equal to a set threshold; Based on the Weber number being greater than or equal to a set threshold, it is determined that factors affecting the tip of the droplet include inertial force and viscous force, and the inertial force is equal to the viscous force.

3. The method for measuring liquid flow properties according to claim 2, wherein: Based on the inertial force being equal to the viscous force, the calculated viscosity of the droplet is determined according to the following calculation formula: Where ρ is the droplet density; η is the calculated viscosity; R n is the maximum radius of the tip; t is the test time from the droplet starting to fall on the substrate to the end of the test; H max is the real-time height of the tip, which changes with the test duration t; Solving formula (1) yields: From formula (2), we can get: Where ΔH max is the tip height change, ΔH max =H0-H max ; H0 is the initial height of the tip when the droplet lands on the substrate; C1 is the first calculation coefficient, where 4. The method for measuring liquid flow properties according to claim 2, wherein: The preset height is greater than or equal to 11.8 cm, and the maximum radius of the tip is between 0.5 mm and 1 mm.

5. The method for measuring liquid flow properties according to claim 1, further comprising: Controlling the Weber number of the droplet to be less than a set threshold; Based on the Weber number being less than a set threshold, determining that factors affecting the tip include viscous force and surface tension, and the viscous force is equal to the surface tension; After the step of calculating the viscosity of the droplet, Based on the fact that the viscous force is equal to the surface tension, the ratio of the cube of the tip height change value to the test duration is determined as the second calculation coefficient. The surface tension coefficient of the surface tension is calculated by the calculated viscosity, the second calculation coefficient and the maximum radius of the tip.

6. The method for measuring liquid flow properties according to claim 5, wherein: The surface tension coefficient of the surface tension is calculated based on the viscous force being equal to the surface tension by using the calculated viscosity, the second calculation coefficient and the maximum radius of the tip, and the calculation formula is: Where ΔH max is the tip height change, ΔH max =H0-H max ; H0 is the initial height of the tip when the droplet lands on the substrate; H max is the real-time height of the tip, which changes with the test duration t; R n is the maximum radius of the tip; η is the calculated viscosity; t is the test time from the droplet starting to fall on the substrate to the end of the test; Surface tension is F = γR n ; γ is the surface tension coefficient, which represents the surface tension per unit length of a straight line segment on the surface of the liquid; Solving formula (3) yields: From formula (4), we can get: Among them, C2 is the second calculation coefficient, where, 7. The method for measuring liquid flow properties according to claim 5, wherein: The preset height is less than 8 cm, and the maximum radius of the tip is between 0.5 mm and 1 mm.

8. The method for measuring the flow properties of a liquid according to any one of claims 2 to 7, wherein: The calculation formula of the Weber number is: Among them, W e is the Weber number; ρ is the droplet density; v0 is the droplet velocity when it just lands on the substrate; V0 is the droplet volume; γ is the surface tension coefficient, which represents the surface tension per unit length of a straight line segment on the surface of the liquid; The dripping speed v0 and the droplet volume V0 are obtained when the droplet just lands on the substrate, and the numerical range of the Weber number is adjusted by controlling the dripping speed v0 and the droplet volume V0.

9. The method for measuring the flow properties of a liquid according to any one of claims 1 to 7, wherein: In the step of controlling the droplets to drip onto the substrate from a preset height, the step further includes: Obtaining the flow time of the droplet in the container; wherein the container is used to contain a liquid, and the liquid forms the droplet at the opening of the container; Obtaining the dripping time from the start of the droplet dripping to the droplet landing on the substrate; The sum of the flow time, the dripping time and the test time is determined to be the total time, and the test time is much shorter than the total time.

10. The method for measuring the flow properties of a liquid according to any one of claims 1 to 7, wherein: Determine the ratio of the tip height change value to the test duration as the first calculation coefficient, The initial height of the tip and a plurality of real-time heights of the tip within the test duration are acquired, and a linear relationship among the first calculation coefficient, the test duration and the change value of the tip height is obtained by fitting.

11. A device for observing liquid droplets, used to perform the method for measuring liquid flow properties according to any one of claims 1 to 10, comprising: A droplet injection component, used for generating droplets, the droplet injection component comprises a first light source emitter, and the dripping direction of the droplets is the same as the emitting direction of the first light emitted by the first light source emitter; A supporting component, one end of which is connected to the droplet injection component, and the other end of which is connected to a stage, and the stage is used to support the light spot sensor; A collection component, used for acquiring an image of the liquid drop falling on the light spot sensor, wherein the collection component is in communication connection with the light spot sensor; Based on the position signal of the first light beam received by the light spot sensor, the collecting component is controlled to move to a collecting position matching the position signal.

12. The device for observing droplets according to claim 11, wherein: The droplet injection component includes a droplet nozzle and a liquid adding component, the outlet of the liquid adding component is toward the liquid inlet at one end of the droplet nozzle, and the other end of the droplet nozzle is provided with a spray port, and the first light source emitter is connected to the droplet nozzle and is coaxially arranged with the spray port so that the first light is emitted from the spray port.

13. The device for observing droplets according to claim 12, wherein: The droplet nozzle comprises: A liquid inlet portion, forming a liquid inlet channel, one end of which is provided with the liquid inlet port; An injection portion, forming an injection channel, the injection portion is connected to the liquid inlet portion, the injection channel is connected to the other end of the liquid inlet channel, and an injection port is arranged at one end of the injection channel away from the liquid inlet channel; A stirring rod is inserted into the injection channel, the stirring rod is coaxially arranged with the injection channel, the stirring rod is connected to the first light source emitter, the end of the stirring rod faces the injection port, and the stirring rod includes a rod body with a light-transmitting structure.

14. The device for observing droplets according to claim 12 or 13, wherein: The liquid adding component is provided with a plurality of liquid adding cavities, the liquid drop nozzle is provided with a plurality of liquid inlets, the liquid adding cavities correspond to the liquid inlets one by one, the outer wall of the stirring rod is provided with a guide groove, and the guide groove is wound around the stirring rod for multiple turns.

15. The device for observing droplets according to any one of claims 11 to 14, further comprising: A blocking component is connected to the supporting component, and a liquid receiving pan of the blocking component moves between an initial position for avoiding the first light and a blocking position for blocking the first light.

16. The device for observing droplets according to any one of claims 11 to 15, further comprising: The blocking component is communicatively connected to the trigger component, and controls the liquid receiving tray to switch from the initial position to the blocking position based on the trigger component receiving the trigger signal of the liquid droplet passing through reaching a set number of times.

17. The device for observing droplets according to claim 16, wherein: The trigger component includes a second light source emitter and a light intensity sensor, the light intensity sensor is used to receive the light signal of the second light emitted by the second light source emitter, the second light source emitter and the light intensity sensor are respectively arranged on both sides of the first light, and the light emission direction of the second light source emitter intersects with the light emission direction of the first light source emitter.

18. The device for observing droplets according to claim 15, wherein: The blocking component also includes a rotating console; a driving device is arranged in the shell of the rotating console, and the output shaft of the driving device is connected to the liquid receiving pan through a cantilever, and the output shaft rotates to drive the liquid receiving pan to rotate between the initial position and the shielding position.

19. The device for observing droplets according to any one of claims 11 to 18, wherein: The acquisition component includes a high-speed camera and a third light source emitter providing a background light source for the high-speed camera; The high-speed camera and the third light source emitter are respectively arranged on both sides of the stage; A three-axis translation stage is connected to the bottom of the high-speed camera. The three-axis translation stage is in communication with the light spot sensor and is configured to adjust the position of the high-speed camera in horizontal, longitudinal and vertical directions so that the high-speed camera is aligned with the acquisition position.

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