Adhesive force measuring device and method based on lever balance method

Abstract

The invention relates to the technical field of micro force value measurement, and discloses an adhesion force measuring device and method based on a lever balance method, the measuring device comprises a lever system, an electrostatic comb tooth system, a liquid drop adhesion measuring system and a measurement and control system; an experiment system comprising a lever, a pivot, a balancing weight, an electrostatic comb tooth body, an electric displacement table, a nanometer micropositioner, a super-hydrophobic surface, a laser interferometer, a plane mirror, a tilt angle sensor and a voltage loading device is built. The method comprises the steps that the experiment system is built; initial voltage is applied to the two ends of the electrostatic comb tooth body, electrostatic force is generated, the nanometer micropositioner is controlled to move downwards at the fixed feeding amount, and the super-hydrophobic surface is made to make slow contact with experimental liquid drops. The electrostatic force generated by the comb teeth serves as a force value transmission medium, the balance state of the lever is monitored in real time in combination with the laser interferometer, high-precision measurement of the adhesive force between the liquid drop and the super-hydrophobic surface is achieved, and the problem that a traditional cantilever beam is insufficient in load capacity is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of tiny force value measurement, and in particular to an adhesion force measurement device and method based on a lever balance method. Background Art

[0002] Wettability characterization has a wide range of applications and importance in the fields of materials science, surface engineering, biomedicine, and microfluidics. Wettability refers to the ability of a liquid to spread on a solid surface, a property that directly affects the flow, coating, and penetration of liquids. Accurately characterizing wettability is of great significance for optimizing material surface properties, developing new functional coatings, improving the sensitivity of biosensors, and designing efficient microfluidic devices.

[0003] Existing wettability is mainly characterized by contact angle measurement. Although this method is simple and widely used, it has limitations on super-hydrophobic or irregular surfaces and faces the problem of reduced accuracy. The force-based measurement method generally provides a more intuitive and quantitative analysis method by directly measuring the vertical adhesion, friction or oscillation force between the experimental droplet and the surface. It mainly includes a balance method, an atomic force microscope method, a laser interferometer method, etc. The balance method is simple to operate and is applicable to a variety of liquids and surfaces, but the measurement sensitivity is relatively low and the dynamic response is extremely poor, which is difficult to meet the needs of high-precision measurement. The atomic force microscope has extremely high force measurement resolution and spatial resolution, and can achieve accurate measurement at the nanometer level, but the evaporation problem is difficult to control, the cantilever frame is easy to break, the measurement range is limited and the cost is high, which limits its wide application. The laser interferometer has a large range, good repeatability, and a high force measurement resolution, but its cost is high and it is easily disturbed by the environment, and the experimental conditions are relatively demanding. Therefore, the present invention provides an adhesion measurement device and method based on a lever balance method to solve the shortcomings in the prior art. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides an adhesion force measurement device and method based on the lever balance method, which solves the limitations of the prior art on super-hydrophobic or irregular surfaces, faces reduced accuracy, is difficult to meet the needs of high-precision measurement, and the evaporation problem is difficult to control, the cantilever frame is easy to break, the measurement range is limited and the cost is high, which limits its wide application.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: an adhesion force measurement device based on a lever balance method, comprising a lever system, an electrostatic comb system, a droplet adhesion measurement system and a measurement and control system;

[0006] The lever system comprises a pivot, a lever and a counterweight, wherein the lever is mounted outside two pivots, and a counterweight is disposed at one end of the lever;

[0007] The electrostatic comb system comprises an electrostatic comb body, the top of which is mounted on the bottom of a lever, and the bottom of which is fixedly connected to an electric displacement platform;

[0008] The droplet adhesion measurement system comprises a super-hydrophobic surface and a nano-micromotion stage, wherein the super-hydrophobic surface is arranged just above one end of a lever, and the super-hydrophobic surface is used to accurately control the contact position with the experimental droplet through the nano-micromotion stage, and the experimental droplet is arranged between the lever and the super-hydrophobic surface;

[0009] The measurement and control system includes a plane reflector, a laser interferometer and an inclination sensor. The plane reflector is arranged on the top of the lever, the laser interferometer is arranged directly above the plane reflector in a horizontal state, and the inclination sensor is installed on the top of the lever to monitor the inclination angle of the lever.

[0010] Preferably, a circular paper piece is provided at the top groove of one end of the lever close to the electrostatic comb body, and the size of the circular paper piece matches the experimental droplet.

[0011] A method for measuring adhesion force based on a lever balance method is also provided, comprising the following steps:

[0012] Build an experimental system including a lever, a pivot, a counterweight, an electrostatic comb body, an electric translation stage, a nano-micromotion stage, a super-hydrophobic surface, a laser interferometer, a plane mirror, a tilt sensor, and a voltage loading device, add experimental droplets, and adjust the position of the counterweight to put the lever in an initial balanced state;

[0013] Apply an initial voltage to both ends of the electrostatic comb body to generate an electrostatic force, adjust the counterweight to rebalance the lever, and record the initial electrostatic force;

[0014] The nano-motion stage is controlled to move downward with a fixed feed amount, so that the super-hydrophobic surface slowly contacts the experimental droplet, during which the position of the counterweight block remains unchanged, and the voltage of the electrostatic comb body is adjusted to keep the lever balanced at all times;

[0015] After the experimental droplet contacts the surface, the nano-micromotion stage is controlled to move upward in the reverse direction, so that the experimental droplet gradually leaves the super-hydrophobic surface. The voltage of the electrostatic comb body is continuously adjusted to maintain the balance of the lever, and the change of the electrostatic force is recorded in real time.

[0016] Based on the calibration data of the electrostatic comb body, the change of the electrostatic force is calculated, and the measured value of the experimental droplet adhesion force is obtained through the relationship between voltage and electrostatic force.

[0017] Preferably, the steps of building the experimental system include:

[0018] Fix the lever on the pivot, connect the electrostatic comb body at one end of the lever, connect the counterweight at the other end, and adjust the counterweight to preliminarily balance the lever;

[0019] An inclination sensor is installed at one end of the lever close to the electrostatic comb body to detect the initial balance state, and a laser interferometer is used to vertically project light onto the plane reflector on the lever to monitor the balance state of the lever in real time;

[0020] The position of the electrostatic comb body is adjusted by an electric translation stage so that it is aligned with the comb teeth under the lever and at an appropriate meshing distance. At the same time, the super-hydrophobic surface is adjusted to be directly above the experimental droplet using a nano-micromotion stage, and the counterweight is adjusted to ensure that the lever is in a balanced state again.

[0021] Preferably, a circular paper piece matching the size of the experimental droplet is placed in the groove on the upper side of the lever at one end of the electrostatic comb body, and a superhydrophobic material is sprayed around it. After drying, the paper piece is removed, the experimental droplet is dripped into the groove, and the lever is restored to balance by adjusting the counterweight.

[0022] Preferably, the initial voltage of the electrostatic force is adjusted in real time by a voltage loading device according to a calibration curve of the experimental system, and the voltage loading device includes a voltage regulator and a micro-current detection device for accurately controlling the application of the electrostatic force.

[0023] Preferably, the displacement feed amount of the nano-fine motion stage is 0.01 to 10 μm / s, and the feed amount is finely adjusted through a precise step control system to ensure precise control of the contact process between the super-hydrophobic surface and the experimental droplet.

[0024] Preferably, the change in electrostatic force is calculated by the voltage change at both ends of the electrostatic comb body, and the calculation includes obtaining an accurate adhesion force value through voltage change based on the linear relationship between voltage and electrostatic force, thereby ensuring high accuracy and fast feedback of data.

[0025] Preferably, the calculation formula between the voltage and the electrostatic force is:

[0026] F e =α·U(t) 2 ;

[0027] Among them, F e is the change in electrostatic force, α is the proportional constant between voltage and electrostatic force, which usually needs to be obtained through experimental calibration, U(t) is the voltage across the electrostatic comb body, and t is the time variable, which represents a certain moment in the experiment.

[0028] Preferably, the laser interferometer is used to monitor the change in the tilt angle of the lever in real time, and combined with the data from the inclination sensor, the angle deviation of the lever is calculated through a microprocessor, and this is used as a feedback signal to dynamically adjust the voltage of the electrostatic comb body to ensure that the lever remains balanced throughout the entire measurement process, thereby improving measurement accuracy.

[0029] The present invention provides an adhesion force measurement device and method based on a lever balance method, which has the following beneficial effects:

[0030] 1. The present invention adopts an electrostatic force control method based on the lever balance method. By adjusting the voltage of the electrostatic comb body in real time, it ensures that the lever system is always in a balanced state during the experiment, thereby accurately measuring the adhesion force of the experimental droplet. The technical effect of high-precision and real-time monitoring is achieved. Compared with the solution in the prior art that relies on direct contact force sensors for measurement, the present invention avoids additional mechanical contact interference and solves the problem of limited measurement accuracy and susceptibility to external vibration.

[0031] 2. The present invention uses an electrostatic comb system to control the force application process, and combines a laser interferometer to measure the micro-displacement of the lever to ensure that the separation process of the experimental droplet and the super-hydrophobic surface is controllable and the data collection is more accurate. The technical effect of non-contact force measurement and high-sensitivity detection is achieved. Compared with the traditional solution of measuring tiny forces using elastic material deformation, the present invention reduces the measurement deviation caused by material aging and elastic recovery errors, and solves the problem of unstable data after long-term use.

[0032] 3. The present invention adds a nano-micro-motion stage to the experimental system, and uses high-precision step control to gradually make the experimental droplets contact or detach from the super-hydrophobic surface, thereby ensuring the repeatability of the experimental process and reducing the impact of environmental disturbances on the experimental data. The technical effect of adjustable measurement accuracy and minimized experimental errors is achieved. Compared with the method of manually controlling the experimental droplet separation process in the prior art, the present invention avoids data fluctuations caused by human errors and solves the problems of poor repeatability and difficulty in strictly controlling experimental conditions.

[0033] 4. The present invention adopts a combination of experimental calibration and theoretical calculation, and accurately models the voltage and force relationship of the electrostatic comb body, so that the calculation of the experimental droplet adhesion force is more accurate. The technical effect of mutual verification between theoretical calculation and experimental measurement is achieved. Compared with the traditional empirical formula method for calculating the experimental droplet adhesion force, the present invention introduces a real-time correction mechanism to solve the problems of unstable experimental data and measurement results relying on a single model assumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a structural diagram of the experimental droplet adhesion experimental system of the present invention;

[0035] Figure 2 It is a schematic diagram of the experimental liquid droplet addition process of the present invention;

[0036] Figure 3 It is a lever force diagram of the contact process between the experimental droplet and the super-hydrophobic surface of the present invention;

[0037] Figure 4 It is a lever force diagram of the separation process between the experimental droplet and the super-hydrophobic surface of the present invention;

[0038] Figure 5 The present invention is a method flow.

[0039] Among them, 1. pivot; 2. counterweight; 3. electrostatic comb body; 4. electric displacement stage; 5. experimental droplet; 6. super-hydrophobic surface; 7. nano-micro-motion stage; 8. tilt sensor; 9. laser interferometer; 10. plane mirror. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the specification of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] Please see attached Figure 1 - Attachment Figure 4, an adhesion force measurement device based on a lever balance method, comprising a lever system, an electrostatic comb system, a droplet adhesion measurement system and a measurement and control system, wherein the lever system comprises a pivot 1, the pivot 1 is used as a fulcrum of the lever to ensure that the lever can rotate around it, a lever, the lever is used to transmit force and respond to the change of torque under the adhesion of the experimental droplet 5, a counterweight 2, the counterweight 2 is used to control the initial equilibrium state of the lever by adjusting the mass and position of the counterweight 2, the lever is installed outside the two pivots 1, and a counterweight 2 is provided at one end of the lever; the electrostatic comb system comprises an electrostatic comb body 3, the electrostatic comb body 3 is used to accurately control the movement of the lever through the action of electrostatic force, the top of the electrostatic comb body 3 is installed at the bottom of the lever, the bottom of the electrostatic comb body 3 is fixedly connected to an electric displacement stage 4, and the electric displacement stage 4 is used to adjust the relative position of the electrostatic comb body 3 and the lever; the droplet adhesion measurement system comprises a super-hydrophobic surface 6, the super-hydrophobic surface 6 is used as the action base of the experimental droplet 5 adhesion experiment, and the nano-micro-motion stage 7 is used to accurately control the super-hydrophobic surface 6 is used to precisely control the contact position between the experimental droplet 5 and the experimental droplet 5, the super-hydrophobic surface 6 is arranged just above one end of the lever, the super-hydrophobic surface 6 is used to precisely control the contact position between the experimental droplet 5 and the experimental droplet 5 through the nano-micro-motion stage 7, the experimental droplet 5 is arranged between the lever and the super-hydrophobic surface 6, the experimental droplet 5 is the experimental object, and the interaction force between the lever and the super-hydrophobic surface 6 will cause a slight change in the angle of the lever; the measurement and control system includes a plane mirror 10, a laser interferometer 9 and a tilt sensor 8, the plane mirror 10 is used to provide a stable optical reflection interface, the laser interferometer 9 is used to detect extremely slight changes in the angle of the lever through interference measurement technology, the plane mirror 10 is arranged on the top of the lever, the laser interferometer 9 is arranged just above the plane mirror 10 in a horizontal state, and the tilt sensor 8 is installed on the top of the lever for real-time monitoring of the tilt angle of the lever and transmitting data to the control system; a circular paper piece is arranged at the top groove of one end of the lever close to the electrostatic comb body 3, and the size of the circular paper piece matches the experimental droplet 5.

[0042] Please see attached Figure 2 -Attached Figure 5 , and also provides an adhesion force measurement method based on a lever balance method, comprising the following steps:

[0043] S1. Build an experimental system including a lever, a pivot 1, a counterweight 2, an electrostatic comb body 3, an electric displacement stage 4, a nano-micromotion stage 7, a super-hydrophobic surface 6, a tilt sensor 8, a laser interferometer 9, a plane mirror 10 and a voltage loading device, drip an experimental droplet 5 and adjust the position of the counterweight 2 to make the lever in an initial balanced state;

[0044] S2, applying an initial voltage to both ends of the electrostatic comb body 3 to generate an electrostatic force, adjusting the counterweight 2 to balance the lever again, and recording the initial electrostatic force;

[0045] S3, control the nano-fine motion stage 7 to move downward with a fixed feed amount, so that the super-hydrophobic surface 6 slowly contacts the experimental droplet 5, during which the position of the counterweight block 2 remains unchanged, and the voltage of the electrostatic comb body 3 is adjusted to keep the lever balanced at all times;

[0046] S4, after the experimental droplet 5 contacts, the nano-micromotion stage 7 is reversely controlled to move upward, so that the experimental droplet 5 gradually separates from the super-hydrophobic surface 6, the voltage of the electrostatic comb body 3 is continuously adjusted to maintain the balance of the lever, and the change of the electrostatic force is recorded in real time;

[0047] S5. Based on the calibration data of the electrostatic comb body 3, the variation of the electrostatic force is calculated, and the measured value of the adhesion force of the experimental droplet 5 is obtained by converting the relationship between voltage and electrostatic force.

[0048] For step S1, in this embodiment, the construction of the experimental system includes the following key steps: The lever system is composed of a lever, a pivot 1, and a counterweight 2, one end of the lever is fixed to the pivot 1, and the other end is installed with the counterweight 2 to adjust the initial balance state of the system.

[0049] The electrostatic comb system includes an electrostatic comb body 3 component and an electric displacement stage 4. The top of the electrostatic comb body 3 is connected to the bottom of the lever, and the lower end is fixed on the electric displacement stage 4. The electric displacement stage 4 is used to fine-tune the position of the electrostatic comb body 3 to ensure the stability of the electrostatic force.

[0050] The droplet 5 adhesion measurement system includes a nano-micromotion stage 7 and a super-hydrophobic surface 6. The super-hydrophobic surface 6 is fixed just above one end of the lever system. The nano-micromotion stage 7 controls the relative position between it and the experimental droplet 5, so that the experimental droplet 5 can stably contact or separate. The experimental droplet 5 is placed in the groove on the upper side of the lever to prevent accidental sliding.

[0051] The measurement and control system consists of a laser interferometer 9, a plane reflector 10 and an inclination sensor 8. The plane reflector 10 is installed on the top of the lever, and the laser interferometer 9 is vertically aligned with the reflector to monitor the slight displacement changes of the lever and maintain the balance of the lever by adjusting the voltage of the electrostatic comb body 3. The inclination sensor 8 is used to monitor the angle changes of the lever to ensure the initial horizontal state of the lever.

[0052] In some embodiments, to improve the measurement accuracy, a circular paper piece matching the size of the experimental droplet 5 can be placed in the groove at one end of the lever close to the electrostatic comb body 3, and the super-hydrophobic material can be sprayed. After the material is dried, the paper piece is removed, and the experimental droplet 5 is dripped into the groove to ensure that the experimental droplet 5 remains in a fixed position during the experiment.

[0053] After the experimental system is built, adjust the counterweight 2 to make the lever reach the initial balance state.

[0054] Generally, after the lever reaches initial balance, the experimental system can enter the subsequent measurement step. The inclination sensor 8 monitors the initial state of the lever, and the laser interferometer measures the small displacement of the lever to ensure its balance. As an option, the voltage of the electrostatic comb body 3 can be dynamically adjusted to compensate for the influence of the external environment and improve the stability of the system.

[0055] For step S2, in this embodiment, an initial voltage U0 is applied across the electrostatic comb body 3, and at this time, the electrostatic comb body 3 generates an electrostatic force F e0 In general, the magnitude of the electrostatic force of the electrostatic comb body 3 is affected by the square relationship of the voltage, which conforms to the following formula:

[0056]

[0057] Among them, F e0 is the initial electrostatic force, the electrostatic force generated after the initial voltage is applied to the electrostatic comb body 3, N is the logarithm of the electrostatic comb body 3, ε0 is the vacuum dielectric constant, t is the comb width, and d is the distance between the teeth of the electrostatic comb body 3. In a possible implementation, the application of the initial electrostatic force may cause the lever to lose balance, so it is necessary to fine-tune the position of the counterweight 2 to restore the lever to a horizontal position. At this time, the elastic restoring force F at the right end of the lever m The equilibrium relationship with the electrostatic force is:

[0058]

[0059] Among them, F m is the elastic restoring force at the right end of the comb teeth, F e0 is the initial electrostatic force, which is the electrostatic force generated after the initial voltage is applied to the electrostatic comb body 3, N is the number of teeth of the electrostatic comb body 3, ε0 is the vacuum dielectric constant, and U0 is the voltage initially applied to the electrostatic comb body 3.

[0060] During the adjustment process, the displacement change of the lever is measured by a laser interferometer 9 to ensure that it is restored to the level.

[0061] In some embodiments, in order to further improve the measurement accuracy, a voltage loading device of the electrostatic comb body 3 can be combined to monitor the voltage application in real time and fine-tune the electrostatic force.

[0062] Generally, after the electrostatic force is applied, the system enters a stable state, and the electrostatic force F e0 This is used as the reference force value for measuring the adhesion force of droplet 5 in the subsequent experiment. At this time, the force state of the lever satisfies the following conditions:

[0063]

[0064] Among them, F crepresents the additional force acting on the lever when the experimental droplet 5 contacts, kΔx represents the restoring force caused by the elastic displacement of the lever, N is the number of teeth of the electrostatic comb body 3, ε0 is the vacuum dielectric constant, and U is the voltage applied to the electrostatic comb body 3.

[0065] For step S3, in order to make the experimental droplet 5 contact the super-hydrophobic surface 6, it is necessary to control the nano-micromotion stage 7 to move downward with a fixed feed amount and keep the lever balanced. Generally, the feed amount of the nano-micromotion stage 7 is set in the range of 0.01 to 10 μm / s to avoid additional disturbance of the experimental droplet 5.

[0066] Specifically, as the experimental droplet 5 gradually approaches the super-hydrophobic surface 6, the contact area gradually expands due to the adhesion of the experimental droplet 5 to form a contact interface. In some embodiments, in order to prevent the experimental droplet 5 from sliding sideways, the geometric structure of the lever surface can be optimized to enhance its stability.

[0067] During the contact process of the experimental droplet 5, the lever produces a small displacement due to the influence of the adhesion force. At this time, in order to maintain the balance state of the lever, it is necessary to dynamically adjust the voltage of the static comb teeth to generate a corresponding electrostatic force to compensate for the force change of the lever. In general, the electrostatic force F of the electrostatic comb tooth body 3 is e It is proportional to the square of the applied voltage and satisfies the following formula:

[0068]

[0069] Among them, F e1 It refers to the electrostatic force generated by the comb teeth during the droplet contact process, N is the number of teeth of the electrostatic comb body 3, ε0 is the vacuum dielectric constant, and U2 is the voltage applied to the electrostatic comb body 3.

[0070] In some embodiments, in order to improve the measurement accuracy, the real-time monitoring data of the laser interferometer 9 can be combined to calculate the change in the electrostatic force during the separation of the experimental droplet 5, and the force of the experimental droplet 5 can be calculated according to the following formula:

[0071]

[0072] Among them, F d1 is the force acting on the experimental droplet 5 during contact with the super-hydrophobic surface 6, F e0 is the initial electrostatic force, which means the electrostatic force before the experimental droplet 5 touches the super-hydrophobic surface 6, F e1 is the electrostatic force generated when the experimental droplet 5 contacts the super-hydrophobic surface 6, U1 is the voltage of the electrostatic comb body 3 applied at this time, N is the number of teeth of the electrostatic comb body 3, ε0 is the vacuum dielectric constant, and U0 is the initial voltage of the electrostatic comb body 3.

[0073] In a possible implementation, the voltage of the electrostatic comb body 3 is adjusted by a closed-loop control system, combined with real-time feedback from the laser interferometer 9, so that the lever maintains dynamic balance. Specifically, the laser interferometer 9 measures the change in the tilt angle of the lever, and calculates the corresponding voltage adjustment through a microprocessor to compensate for the force change caused by the contact of the experimental droplet 5.

[0074] In some embodiments, as an option, historical experimental data may be combined to establish an empirical model between the electrostatic force and the contact force of the experimental droplet 5 to improve the stability and repeatability of the measurement.

[0075] For step S4, in this embodiment, it is necessary to reversely control the nano-micromotion stage 7 to gradually separate the experimental droplet 5 from the super-hydrophobic surface 6, and maintain the lever balance by adjusting the voltage of the electrostatic comb body 3 in real time, and record the change of the electrostatic force at the same time. First, the super-hydrophobic surface 6 is precisely controlled to move upward by the nano-micromotion stage 7 to gradually separate the experimental droplet 5. In general, in order to ensure the stability of the separation process of the experimental droplet 5, the feed rate of the nano-micromotion stage 7 is set in the range of 0.01 to 10 microns / second to avoid additional disturbance of the experimental droplet 5.

[0076] Specifically, as the super-hydrophobic surface 6 gradually moves upward, the contact area between the experimental droplet 5 and the surface gradually decreases. At this time, due to the effect of adhesion, the experimental droplet 5 still maintains a certain degree of interaction with the super-hydrophobic surface 6, causing the lever to tilt. In order to maintain the balance of the lever, it is necessary to continuously adjust the voltage of the electrostatic comb body 3 so that the electrostatic force F e The elastic restoring force F at the right end of the lever m Match.

[0077] In a possible implementation, the magnitude of the electrostatic force of the electrostatic comb body 3 is affected by the applied voltage and satisfies the following relationship:

[0078]

[0079] Among them, F e2 It refers to the electrostatic force after the droplet is completely separated, which is used as the final force value reference, N is the number of teeth of the electrostatic comb body 3, ε0 is the vacuum dielectric constant, and U2 is the voltage applied to the electrostatic comb body 3.

[0080] In some embodiments, in order to improve the measurement accuracy, the real-time monitoring data of the laser interferometer 9 can be combined and the desorption force of the experimental droplet 5 can be calculated according to the following formula:

[0081]

[0082] Among them, F d2 represents the force during the separation of the experimental droplet 5 from the super-hydrophobic surface 6, Fe0 is the initial electrostatic force, which represents the electrostatic force before the experimental droplet 5 touches the super-hydrophobic surface 6, U0 is the initial voltage of the electrostatic comb body 3, N is the number of teeth of the electrostatic comb body 3, ε0 is the vacuum dielectric constant, U2 is the voltage applied to the electrostatic comb body 3, and d is the electrode spacing between the comb teeth.

[0083] As an option, in order to further optimize the measurement accuracy, a relationship model between the separation force of the experimental droplet 5 and the voltage change can be constructed. In some embodiments, the voltage control strategy of the electrostatic comb body 3 can also be optimized in combination with historical experimental data to reduce measurement errors.

[0084] For step S5, in this embodiment, after the experimental droplet 5 is completely separated from the super-hydrophobic surface 6, the experimental system enters the measurement data processing and calculation stage. The core goal of this step is to accurately solve the adhesion force of the experimental droplet 5 based on the change in the electrostatic force of the electrostatic comb body 3 system. In general, after the experimental droplet 5 is detached, the lever returns to a new equilibrium state, and the voltage of the electrostatic comb body 3 is also adjusted accordingly. As an option, the adhesion force of the experimental droplet 5 can be obtained by measuring the change in the voltage of the electrostatic comb body 3 before and after the contact of the experimental droplet 5, and combining it with the electrostatic force calculation method calibrated by the experiment. In a possible implementation method, the small displacement of the lever measured by the laser interferometer 9 can be combined to further correct the calculation of the electrostatic force to ensure the accuracy and repeatability of the experimental data.

[0085] In this embodiment, the adhesion force of the experimental droplet 5 is calculated based on the electrostatic force change of the electrostatic comb body 3 system. Specifically, the relationship between the electrostatic force and the applied voltage can be obtained through experimental calibration and expressed by the following formula:

[0086] F e =α·U(t) 2 ;

[0087] Among them, F e is the variation of electrostatic force, which refers to the force generated by the electrostatic effect, α is the proportional constant obtained by experimental calibration, U(t) is the voltage across the electrostatic comb body 3, and t is a certain moment in the experiment.

[0088] In some embodiments, in order to improve the measurement accuracy, the proportional constant α can be corrected in combination with experimental calibration data. In general, α is affected by the number of teeth of the electrostatic comb body 3, the distance between teeth, and the dielectric properties of the material, so its accurate value can be determined through multiple experiments. Specifically, under standard conditions of known electrostatic force, the force values ​​under different voltages can be measured, and the optimal α value can be obtained by least squares fitting to reduce system errors.

[0089] In another possible implementation, the electrostatic force can also be solved using a theoretical calculation model. Specifically, the electrostatic force is proportional to the square of the voltage, and its theoretical calculation formula is as follows:

[0090]

[0091] Among them, F e is the electrostatic force, which refers to the force generated by the electrostatic effect, N is the number of teeth of the electrostatic comb body 3, ε0 is the vacuum dielectric constant, t is the comb width, d is the distance between the comb teeth, and U is the voltage applied by the electrostatic comb body 3. Before and after the experimental droplet is completely detached, the change in electrostatic force can be calculated by the following formula:

[0092]

[0093] Where, ΔF e is the change in electrostatic force, N is the number of teeth of the electrostatic comb body 3, ε0 is the vacuum dielectric constant, U and U0 are the contact separation and initial voltages of the electrostatic comb body 3 of the experimental droplet 5, respectively, W is the comb width, and d is the distance between the comb teeth.

[0094] In general, the adhesion force of the experimental droplet 5 can be converted from the change in electrostatic force, that is:

[0095] F a =ΔF e ;

[0096] Among them, F a It represents the total force generated by the droplet when the voltage is U, ΔF e Representation force F e The change from U0 to U.

[0097] In some embodiments, in order to reduce the impact of environmental factors on the measurement accuracy, corrections can be made in combination with the data of the laser interferometer 9. Specifically, the laser interferometer 9 can monitor the slight tilt angle changes of the lever, and in combination with the force balance formula of the lever system, correct the calculation error of the electrostatic force. As an option, the displacement θ measured by the laser interferometer 9 can be used, and the corresponding torque compensation value can be calculated in combination with the geometric parameter L of the lever, so as to obtain a more accurate adhesion force measurement result.

[0098] In some embodiments, the relationship model between electrostatic force and voltage can be optimized in combination with historical experimental data. For example, by measuring the change of electrostatic force under different experimental conditions and establishing an empirical functional relationship between electrostatic force, contact area of ​​experimental droplet 5 and contact time, the stability and repeatability of adhesion force calculation can be optimized.

[0099] Working principle: The adhesion of the experimental droplet 5 is measured by regulating the equilibrium state of the lever system by utilizing electrostatic force, and by precisely controlling the contact and separation process between the experimental droplet 5 and the super-hydrophobic surface 6. First, an initial voltage is loaded at both ends of the electrostatic comb body 3 to generate an electrostatic force to make the lever lose balance, and then the lever is restored to the horizontal level by adjusting the position of the counterweight 2 to establish the initial balance of the system. Subsequently, the nano-micro-motion stage 7 is controlled to drive the super-hydrophobic surface 6 downward with a fixed feed amount, so that it slowly contacts the experimental droplet 5, and then moves upward to achieve the gradual separation of the experimental droplet 5. During the whole process, the position of the counterweight 2 is kept unchanged, and the lever is always maintained in a balanced state only by adjusting the voltage at both ends of the electrostatic comb body 3, and the changes in the voltage at both ends of the electrostatic comb body 3 at different positions are recorded in real time. Through multiple experiments, the average value of the adhesion value of the experimental droplet 5 obtained under each loading voltage is taken as the final measurement result of the adhesion of the experimental droplet 5.

[0100] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An adhesion force measurement device based on a lever balance method, characterized in that: It includes a lever system, an electrostatic comb system, a droplet adhesion measurement system, and a measurement and control system; The lever system comprises a pivot (1), a lever and a counterweight (2), wherein the lever is mounted outside two pivots (1), and a counterweight (2) is disposed at one end of the lever; The electrostatic comb tooth system comprises an electrostatic comb tooth body (3), the top of the electrostatic comb tooth body (3) is mounted on the bottom of the lever, and the bottom of the electrostatic comb tooth body (3) is fixedly connected to an electric displacement platform (4); The droplet adhesion measurement system comprises a super-hydrophobic surface (6) and a nano-micromotion stage (7), wherein the super-hydrophobic surface (6) is arranged directly above one end of a lever, and the super-hydrophobic surface (6) is used to accurately control the contact position between the super-hydrophobic surface (6) and an experimental droplet (5) through the nano-micromotion stage (7), and the experimental droplet (5) is arranged between the lever and the super-hydrophobic surface (6); The measurement and control system comprises a plane reflector (10), a laser interferometer (9) and an inclination sensor (8); the plane reflector (10) is arranged at the top of a lever, the laser interferometer (9) is arranged directly above the plane reflector (10) in a horizontal state, and the inclination sensor (8) is installed at the top of the lever to monitor the inclination angle of the lever.

2. The adhesion force measuring device based on the lever balance method according to claim 1, characterized in that: A circular paper piece is arranged at a groove at the top of one end of the lever close to the electrostatic comb body (3), and the size of the circular paper piece matches the experimental liquid droplet (5).

3. A method for measuring adhesion based on a lever balance method, applied to an adhesion measuring device based on a lever balance method as claimed in any one of claims 1 to 2, characterized in that: The following steps are involved: An experimental system including a lever, a pivot (1), a counterweight (2), an electrostatic comb body (3), an electric displacement stage (4), a nano-micromotion stage (7), a super-hydrophobic surface (6), a tilt sensor (8), a laser interferometer (9), a plane mirror (10) and a voltage loading device is constructed, and an experimental droplet (5) is added and the position of the counterweight (2) is adjusted to put the lever in an initial equilibrium state; Applying an initial voltage to both ends of the electrostatic comb body (3) to generate an electrostatic force, adjusting the counterweight (2) to restore the balance of the lever, and recording the initial electrostatic force; The nano-micro-motion stage (7) is controlled to move downward at a fixed feed rate, so that the super-hydrophobic surface (6) slowly contacts the experimental droplet (5), during which the position of the counterweight (2) remains unchanged, and the voltage of the electrostatic comb body (3) is adjusted to keep the lever balanced at all times; After the experimental droplet (5) contacts, the nano-micromotion stage (7) is reversely controlled to move upward, so that the experimental droplet (5) gradually separates from the super-hydrophobic surface (6), and the voltage of the electrostatic comb body (3) is continuously adjusted to maintain the balance of the lever, and the voltage change is recorded in real time; Based on the calibration data of the electrostatic comb body (3), the change in electrostatic force is calculated by converting the relationship between voltage and electrostatic force, thereby obtaining the measured value of the adhesion force of the experimental droplet (5).

4. The adhesion force measurement method based on the lever balance method according to claim 3, characterized in that: The steps of building the experimental system include: Fix the lever on the pivot (1), connect the electrostatic comb body (3) at one end of the lever, and connect the counterweight (2) at the other end, and adjust the counterweight (2) to preliminarily balance the lever; An inclination sensor (8) is installed at one end of the lever close to the electrostatic comb body (3) to detect the initial balance state, and a laser interferometer (9) is used to vertically incident on a plane reflector (10) on the lever to monitor the balance state of the lever in real time; The position of the electrostatic comb body (3) is adjusted by an electric displacement stage (4) so ​​that it is aligned with the comb teeth below the lever and at an appropriate meshing distance. At the same time, the super-hydrophobic surface (6) is adjusted to be directly above the experimental droplet (5) by a nano-micromotion stage (7) to ensure that the experimental system is in an initial equilibrium state.

5. The adhesion force measurement method based on the lever balance method according to claim 4, characterized in that: A circular paper piece matching the size of the experimental droplet (5) is placed in the groove on the upper side of the lever at one end of the electrostatic comb body (3), and a super-hydrophobic material is sprayed around it. After drying, the paper piece is removed, and the experimental droplet (5) is dripped into the groove. The lever is then restored to balance by adjusting the counterweight (2).

6. The adhesion force measurement method based on the lever balance method according to claim 3, characterized in that: The initial voltage of the electrostatic force is adjusted in real time by a voltage loading device according to a calibration curve of the experimental system. The voltage loading device includes a voltage regulator and a micro-current detection device for accurately controlling the application of the electrostatic force.

7. The adhesion force measurement method based on the lever balance method according to claim 1, characterized in that: The displacement feed amount of the nano-micro-motion stage (7) is 0.01 to 10 micrometers per second, and the feed amount is finely adjusted through a precise step control system to ensure accurate control of the contact process between the super-hydrophobic surface (6) and the experimental droplet (5).

8. The adhesion force measurement method based on the lever balance method according to claim 3, characterized in that: The power variation is dynamically calculated through the voltage variation at both ends of the electrostatic comb body (3). The dynamic calculation includes obtaining an accurate adhesion value using a numerical integration method based on the linear relationship between voltage and electrostatic force, combined with the displacement of the electric displacement stage (4) and the precise measurement value of the nano-micro-motion stage (7), thereby ensuring high data accuracy and rapid feedback.

9. The adhesion force measurement method based on the lever balance method according to claim 8, characterized in that: The calculation formula between the voltage and the electrostatic force is: F e =α·U(t) 2 ; Among them, F e is the variation of electrostatic force, α is the proportional constant between voltage and electrostatic force, which is usually obtained through experimental calibration, U(t) is the voltage across the electrostatic comb body (3), and t is the time variable, which represents a certain moment in the experimental process.

10. The adhesion force measurement method based on the lever balance method according to claim 3, characterized in that: The laser interferometer (9) is used to monitor the change in the tilt angle of the lever in real time, and in combination with the data of the tilt sensor (8), calculate the angle deviation of the lever through a microprocessor, and use this as a feedback signal to dynamically adjust the voltage of the electrostatic comb body (3) to ensure that the lever always remains balanced during the entire measurement process, thereby improving the measurement accuracy.

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