An adhesive force measurement device and method based on lever balance method

Abstract

This invention relates to the field of micro-force measurement technology, and discloses an adhesion force measurement device and method based on the lever balance method. The measuring device includes a lever system, an electrostatic comb system, a droplet adhesion measurement system, and a measurement and control system. An experimental system is constructed, comprising a lever, a pivot, a counterweight, an electrostatic comb body, an electric displacement stage, a nano-micro-motion stage, a superhydrophobic surface, a laser interferometer, a plane mirror, a tilt sensor, and a voltage loading device. The method includes: constructing the experimental system; applying an initial voltage to both ends of the electrostatic comb body to generate electrostatic force; controlling the nano-micro-motion stage to move downwards with a fixed feed rate, causing the superhydrophobic surface to slowly contact the experimental droplet. This invention uses the electrostatic force generated by the comb as a force transmission medium, combined with real-time monitoring of the lever's balance state by a laser interferometer, to achieve high-precision measurement of the adhesion force between the droplet and the superhydrophobic surface, avoiding the problem of insufficient load-bearing capacity of traditional cantilever beams.

Description

Technical Field

[0001] This invention relates to the field of micro-force measurement technology, specifically to an adhesive force measurement device and method based on the lever balance method. Background Technology

[0002] Wettability characterization has a wide range of applications and is of great importance in 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. Accurate characterization of wettability is of great significance for optimizing material surface properties, developing novel functional coatings, improving the sensitivity of biosensors, and designing efficient microfluidic devices.

[0003] Existing methods for characterizing wettability primarily rely on contact angle measurements. While simple and widely used, this approach has limitations on superhydrophobic or irregular surfaces, leading to reduced accuracy. Force-based measurement methods, on the other hand, typically provide more intuitive and quantitative analysis by directly measuring the perpendicular adhesion force, frictional force, or oscillatory force between the experimental droplet and the surface. These methods mainly include the balance method, atomic force microscopy (AFM), and laser interferometry. The balance method is simple to operate and applicable to various liquids and surfaces, but its measurement sensitivity is relatively low and its dynamic response is extremely poor, making it difficult to meet the demands of high-precision measurements. AFM offers extremely high force measurement resolution and spatial resolution, enabling nanometer-level precision measurements, but evaporation is difficult to control, the cantilever is prone to breakage, the measurement range is limited, and the cost is high, restricting its widespread application. Laser interferometry offers a large range, good repeatability, and high force measurement resolution, but its cost is high, it is susceptible to environmental interference, and it has stringent experimental requirements. Therefore, this invention provides an adhesion force measurement device and method based on the lever balance method to address the shortcomings of existing technologies. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides an adhesion force measurement device and method based on the lever balance method. This solves the limitations of existing technologies on superhydrophobic or irregular surfaces, such as reduced accuracy, difficulty in meeting the requirements of high-precision measurement, difficulty in controlling evaporation, easy breakage of the cantilever frame, limited measurement range, and high cost, which restrict their widespread application.

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

[0006] The lever system includes a pivot, a lever, and a counterweight. The lever is mounted on the outside of two pivots, and a counterweight is provided at one end of the lever.

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

[0008] The droplet adhesion measurement system includes a superhydrophobic surface and a nano-micro stage. The superhydrophobic surface is positioned directly above one end of a lever. The superhydrophobic surface is used to precisely control the contact position with the experimental droplet via the nano-micro stage. The experimental droplet is positioned between the lever and the superhydrophobic surface.

[0009] The measurement and control system includes a plane mirror, a laser interferometer, and a tilt sensor. The plane mirror is positioned at the top of the lever, the laser interferometer is positioned directly above the plane mirror when it is horizontal, and the tilt sensor is mounted at the top of the lever to monitor the lever's tilt angle.

[0010] Preferably, a circular paper piece is provided at the top groove of one end of the lever near 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 the lever balance method is also provided, including the following steps:

[0012] An experimental system was constructed, including a lever, pivot, counterweight, electrostatic comb body, electric displacement stage, nano-micro stage, superhydrophobic surface, laser interferometer, plane mirror, tilt sensor and voltage loading device. Experimental liquid droplets were added and the position of the counterweight was adjusted to bring the lever to an initial equilibrium state.

[0013] An initial voltage is applied to both ends of the electrostatic comb body to generate electrostatic force. The counterweight is adjusted to make the lever reach balance again, and the initial electrostatic force is recorded.

[0014] The nano-microstage is controlled to move downwards with a fixed feed rate, so that the superhydrophobic surface slowly contacts the experimental droplet. During this process, the position of the counterweight remains unchanged, and the lever is kept in balance by adjusting the voltage of the electrostatic comb body.

[0015] After the experimental droplet makes contact, the nano-micro stage is moved upward in reverse control so that the experimental droplet gradually detaches from the superhydrophobic surface. The voltage of the electrostatic comb body is continuously adjusted to maintain the lever balance, and the change of electrostatic force is recorded in real time.

[0016] Based on the calibration data of the electrostatic comb body, the change in electrostatic force was calculated, and the measured value of the adhesion force of the experimental droplets was obtained by converting the voltage and electrostatic force.

[0017] Preferably, the steps for setting up the experimental system include:

[0018] Fix the lever to the pivot, connect the electrostatic comb body to one end of the lever, and connect the counterweight to the other end. Adjust the counterweight to initially balance the lever.

[0019] An angle sensor is installed at the end of the lever near the electrostatic comb body to detect the initial balance state, and a laser interferometer is used to vertically incident on the plane mirror 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 displacement stage to align it with the comb teeth below the lever and to an appropriate meshing distance. At the same time, the superhydrophobic surface is adjusted to be directly above the experimental droplet using a nano-micro stage, and the counterweight is adjusted to ensure that the lever is back in a balanced state.

[0021] Preferably, a circular piece of paper 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 is removed, the experimental droplet is added to 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 the calibration curve of the experimental system. The voltage loading device includes a voltage regulator and a micro-current detection device for precisely controlling the application of the electrostatic force.

[0023] Preferably, the displacement feed of the nano-stage is 0.01 to 10 micrometers / second, and the feed is finely adjusted by a precise stepping control system to ensure precise control of the contact process between the superhydrophobic 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. The calculation includes obtaining an accurate adhesion force value based on the linear relationship between voltage and electrostatic force, ensuring high data accuracy and rapid feedback.

[0025] Preferably, the formula for calculating the relationship between voltage and electrostatic force is as follows:

[0026] F e =α·U(t) 2 ;

[0027] Among them, F e Let α be the change in electrostatic force, and let α be the proportionality 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 a time variable, representing a certain moment in the experimental process.

[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 tilt sensor, the microprocessor calculates the angle deviation of the lever, and uses this as a feedback signal to dynamically adjust the voltage of the electrostatic comb body, so as to ensure that the lever remains balanced throughout the measurement process and improve the measurement accuracy.

[0029] This invention provides an adhesive force measuring device and method based on the lever balance method. It has the following beneficial effects:

[0030] 1. This invention employs an electrostatic force control method based on lever balance. By adjusting the voltage of the electrostatic comb body in real time, it ensures that the lever system remains in a balanced state throughout the experiment, thereby accurately measuring the adhesion force of the experimental droplets. This achieves high precision and real-time monitoring. Compared to existing technologies that rely on direct contact force sensors for measurement, this invention avoids additional mechanical contact interference and solves the problems of limited measurement accuracy and susceptibility to external vibrations.

[0031] 2. This invention employs an electrostatic comb system to control the force application process and combines it with a laser interferometer to measure the micro-displacement of the lever, ensuring that the separation process between the experimental droplet and the superhydrophobic surface is controllable and data acquisition is more accurate. It achieves the technical effect of non-contact force measurement and high-sensitivity detection. Compared to traditional methods that utilize elastic material deformation to measure minute forces, this invention reduces measurement deviations caused by material aging and elastic recovery errors, and solves the problem of data instability after long-term use.

[0032] 3. This invention incorporates a nano-microstage into the experimental system, using high-precision step control to gradually bring the experimental droplets into or out of the superhydrophobic surface, ensuring the repeatability of the experimental process and reducing the impact of environmental disturbances on the experimental data. This achieves the technical effect of adjustable measurement accuracy and minimized experimental error. Compared to existing methods that manually control the droplet separation process, this invention avoids data fluctuations caused by human error and solves the problems of poor repeatability and difficulty in strictly controlling experimental conditions.

[0033] 4. This invention combines experimental calibration with theoretical calculation, using precise modeling of the voltage and force relationship of the electrostatic comb body to make the calculation of droplet adhesion force more accurate. It achieves the technical effect of mutual verification between theoretical calculation and experimental measurement. Compared with traditional empirical formulas for calculating droplet adhesion force, this invention introduces a real-time correction mechanism, solving the shortcomings of unstable experimental data and measurement results relying on a single model assumption. Attached Figure Description

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

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

[0036] Figure 3 This is a lever force diagram showing the contact process between the experimental droplet and the superhydrophobic surface in this invention.

[0037] Figure 4 This is a lever force diagram showing the separation process of the experimental droplet from the superhydrophobic surface according to the present invention.

[0038] Figure 5 This is the method flow of the present invention.

[0039] Among them, 1. Pivot; 2. Counterweight; 3. Electrostatic comb body; 4. Electric displacement stage; 5. Experimental droplet; 6. Superhydrophobic surface; 7. Nanoscale micro-motion stage; 8. Tilt sensor; 9. Laser interferometer; 10. Plane mirror. Detailed Implementation

[0040] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] Please see the appendix Figure 1 - Appendix Figure 4An adhesion force measurement device based on the lever balance method includes a lever system, an electrostatic comb system, a droplet adhesion measurement system, and a measurement and control system. The lever system includes a pivot 1, which serves as the fulcrum of the lever, ensuring its rotation. The lever transmits force and responds to torque changes under the adhesion of experimental droplets 5. A counterweight 2 is used to control the initial balance of the lever by adjusting its mass and position. The lever is mounted outside the two pivots 1, with the counterweight 2 at one end. The electrostatic comb system includes an electrostatic comb body 3, which precisely controls the movement of the lever through electrostatic force. The top of the electrostatic comb body 3 is mounted on the bottom of the lever, and an electric displacement stage 4 is fixedly connected to the bottom of the electrostatic comb body 3. The electric displacement stage 4 adjusts the relative position of the electrostatic comb body 3 and the lever. The droplet adhesion measurement system includes a superhydrophobic surface 6, which serves as the substrate for the adhesion experiment of experimental droplets 5. A nano-micro-motion stage 7 is used to precisely control the superhydrophobic surface. The contact position between the superhydrophobic surface 6 and the experimental droplet 5 is determined by the superhydrophobic surface 6 positioned directly above one end of the lever. The superhydrophobic surface 6 is used to precisely control the contact position with the experimental droplet 5 via the nano-micro-motion stage 7. The experimental droplet 5 is positioned between the lever and the superhydrophobic surface 6, serving as the experimental object. The interaction force between the droplet 5 and the lever and the superhydrophobic surface 6 will cause a minute change in the lever angle. The measurement and control system includes a plane mirror 10, a laser interferometer 9, and a tilt sensor 8. The plane mirror 10 provides a stable optical reflection interface. The laser interferometer 9 detects minute changes in the lever angle using interferometry. The plane mirror 10 is positioned at the top of the lever, and the laser interferometer 9 is positioned directly above the horizontal plane mirror 10. The tilt sensor 8 is mounted at the top of the lever to monitor the lever's tilt angle in real time and transmit the data to the control system. A circular piece of paper, matching the size of the experimental droplet 5, is placed in the groove at the top end of the lever near the electrostatic comb body 3.

[0042] Please see the appendix Figure 2 - Appendix Figure 5 Furthermore, a method for measuring adhesion force based on the lever balance method is provided, comprising the following steps:

[0043] S1. Construct an experimental system including a lever, pivot 1, counterweight 2, electrostatic comb body 3, electric displacement stage 4, nano-micro stage 7, superhydrophobic surface 6, tilt sensor 8, laser interferometer 9, plane mirror 10, and voltage loading device. Add experimental liquid drop 5 and adjust the position of counterweight 2 to bring the lever to an initial equilibrium state.

[0044] S2. Apply an initial voltage to both ends of the electrostatic comb body 3 to generate electrostatic force. Adjust the counterweight 2 to make the lever reach balance again and record the initial electrostatic force.

[0045] S3. Control the nano-micro stage 7 to move downwards with a fixed feed rate, so that the superhydrophobic surface 6 slowly contacts the experimental droplet 5. During this period, keep the position of the counterweight 2 unchanged, and keep the lever balanced by adjusting the voltage of the electrostatic comb body 3.

[0046] S4. After the experimental droplet 5 comes into contact, the nano-micro stage 7 is controlled to move upward in the opposite direction, so that the experimental droplet 5 gradually detaches from the superhydrophobic surface 6. The voltage of the electrostatic comb body 3 is continuously adjusted to maintain the lever balance, and the change of electrostatic force is recorded in real time.

[0047] S5. Based on the calibration data of the electrostatic comb body 3, calculate the change in electrostatic force, and convert the measured value of the adhesion force of the experimental droplet 5 by 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 consists 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 equipped with the counterweight 2 to adjust the initial balance of the system.

[0049] The electrostatic comb system includes an electrostatic comb body 3 and an electric displacement stage 4. The top of the electrostatic comb body 3 is connected to the bottom of a lever, and the lower end is fixed to 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 adhesion measurement system includes a nano-stage 7 and a superhydrophobic surface 6, which is fixed directly above one end of the lever system. The nano-stage 7 controls its relative position to the experimental droplet 5, enabling the droplet 5 to stably contact or separate. The experimental droplet 5 is placed in a groove on the upper side of the lever to prevent accidental slippage.

[0051] The measurement and control system consists of a laser interferometer 9, a plane mirror 10, and a tilt sensor 8. The plane mirror 10 is mounted on top of the lever, and the laser interferometer 9 is vertically aligned with the mirror to monitor minute displacement changes in the lever and maintain lever balance by adjusting the voltage of the electrostatic comb body 3. The tilt sensor 8 is used to monitor changes in the lever angle to ensure the lever's initial horizontal state.

[0052] In some embodiments, to improve measurement accuracy, a circular piece of paper matching the size of the experimental droplet 5 can be placed in the groove at one end of the lever near the electrostatic comb body 3, and coated with a superhydrophobic material. After the material dries, the paper is removed, and the experimental droplet 5 is added to the groove to ensure that the experimental droplet 5 remains in a fixed position during the experiment.

[0053] After the experimental system was set up, the counterweight 2 was adjusted to bring the lever to an initial equilibrium state.

[0054] Under normal circumstances, after the lever reaches initial equilibrium, the experimental system can proceed to subsequent measurement steps. The tilt sensor 8 monitors the initial state of the lever, and the laser interferometer measures minute displacements of the lever to ensure its balance. Alternatively, the voltage of the electrostatic comb body 3 can be dynamically adjusted to compensate for external environmental influences and improve system stability.

[0055] For step S2, in this embodiment, an initial voltage U0 is applied to both ends of the electrostatic comb body 3, at which time the electrostatic comb body 3 generates an electrostatic force F. e0 Generally, the magnitude of the electrostatic force on the electrostatic comb body 3 is affected by the square of the voltage, conforming to the following formula:

[0056]

[0057] Among them, F e0 Let N be the initial electrostatic force, generated after applying an initial voltage to the electrostatic comb body 3. Let N be the logarithm of the electrostatic comb body 3, ε0 be the vacuum permittivity, t be the comb width, and d be the inter-tooth distance of the electrostatic comb body 3. In one possible implementation, the application of the initial electrostatic force may cause the lever to lose balance, thus requiring fine-tuning 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 It satisfies a balance relationship with electrostatic force:

[0058]

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

[0060] During the adjustment process, the displacement of the lever is measured using a laser interferometer 9 to ensure that it is restored to a horizontal position.

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

[0062] Under normal circumstances, after an electrostatic force is applied, the system enters a steady state, and the electrostatic force F... e0 This serves as the reference force value for measuring the adhesion force of droplet 5 in subsequent experiments. At this point, the force state of the lever satisfies the following conditions:

[0063]

[0064] Among them, F cε represents the additional force acting on the lever when the experimental droplet 5 comes into contact with it, 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 superhydrophobic surface 6, the nanostage 7 needs to be controlled to move downwards with a fixed feed rate while maintaining lever balance. Generally, the feed rate of the nanostage 7 is set in the range of 0.01 to 10 micrometers / second to avoid additional disturbance to the experimental droplet 5.

[0066] Specifically, as the experimental droplet 5 gradually approaches the superhydrophobic surface 6, the contact area gradually expands due to the adhesive force of the experimental droplet 5, forming a contact interface. In some embodiments, to prevent the experimental droplet 5 from sliding laterally, its stability can be enhanced by optimizing the geometry of the lever surface.

[0067] During the contact process of the experimental droplet 5, the lever undergoes a slight displacement due to the adhesive force. At this time, to maintain the balance 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 change in force on the lever. Generally, the electrostatic force F of the electrostatic comb tooth body 3... e It is proportional to the square of the applied voltage, satisfying the following formula:

[0068]

[0069] Among them, F e1 The electrostatic force generated by the comb teeth during the contact of the droplets is N, where N is the number of teeth in 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, to improve measurement accuracy, the change in electrostatic force during the separation of the experimental droplet 5 can be calculated by combining the real-time monitoring data of the laser interferometer 9, and the force exerted by the experimental droplet 5 can be calculated according to the following formula:

[0071]

[0072] Among them, F d1 F represents the force exerted during the contact process between the experimental droplet 5 and the superhydrophobic surface 6. e0 F represents the initial electrostatic force, indicating the electrostatic force before the experimental droplet 5 touches the superhydrophobic surface 6. e1 U1 is the electrostatic force generated when the experimental droplet 5 comes into contact with the superhydrophobic surface 6, 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 one possible implementation, the voltage adjustment of the electrostatic comb body 3 employs a closed-loop control system, combined with real-time feedback from the laser interferometer 9, to maintain the lever in dynamic equilibrium. Specifically, the laser interferometer 9 measures the change in the lever's tilt angle and calculates the corresponding voltage adjustment amount via a microprocessor to compensate for force changes caused by the contact of the experimental droplet 5.

[0074] In some embodiments, as an option, an empirical model can be established by incorporating historical experimental data to improve the stability and repeatability of the measurement.

[0075] For step S4, in this embodiment, the nano-microstage 7 needs to be controlled in reverse to gradually detach the experimental droplet 5 from the superhydrophobic surface 6. Lever balance is maintained by adjusting the voltage of the electrostatic comb body 3 in real time, while recording the changes in electrostatic force. First, the nano-microstage 7 precisely controls the upward movement of the superhydrophobic surface 6, causing the experimental droplet 5 to gradually detach. Generally, to ensure the stability of the experimental droplet 5 separation process, the feed rate of the nano-microstage 7 is set within the range of 0.01 to 10 micrometers per second to avoid additional disturbance to the experimental droplet 5.

[0076] Specifically, as the superhydrophobic surface 6 gradually moves upward, the contact area between the experimental droplet 5 and the surface gradually decreases. At this point, due to the adhesive force, the experimental droplet 5 still maintains a certain degree of interaction with the superhydrophobic surface 6, causing the lever to tilt. To maintain the lever balance, the voltage of the electrostatic comb body 3 needs to be continuously adjusted to make the electrostatic force F... e The elastic restoring force F at the right end of the lever m Matching.

[0077] In one possible implementation, the magnitude of the electrostatic force on the electrostatic comb body 3 is affected by the applied voltage, satisfying the following relationship:

[0078]

[0079] Among them, F e2 The electrostatic force after the droplet has completely detached 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, to improve measurement accuracy, real-time monitoring data from the laser interferometer 9 can be used, and the desorption force of the experimental droplet 5 can be calculated according to the following formula:

[0081]

[0082] Among them, F d2 F represents the force acting during the separation of experimental droplet 5 from the superhydrophobic surface 6.e0 U0 is the initial electrostatic force, representing the electrostatic force before the experimental droplet 5 touches the superhydrophobic 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] Alternatively, to further optimize measurement accuracy, a model relating the separation force of the experimental droplet 5 to voltage changes can be constructed. In some embodiments, historical experimental data can also be used to optimize the voltage control strategy of the electrostatic comb body 3 to reduce measurement errors.

[0084] For step S5, in this embodiment, after the experimental droplet 5 is completely separated from the superhydrophobic surface 6, the experimental system enters the measurement data processing and calculation stage. The core objective of this step is to accurately calculate the adhesion force of the experimental droplet 5 based on the electrostatic force change of the electrostatic comb body 3 system. Generally, after the experimental droplet 5 detaches, the lever returns to a new equilibrium state, and the voltage of the electrostatic comb body 3 is adjusted accordingly. Alternatively, the adhesion force of the experimental droplet 5 can be obtained by measuring the change in voltage of the electrostatic comb body 3 before and after the experimental droplet 5 contacts the surface, combined with the electrostatic force calculation method calibrated by the experiment. In one possible implementation, the minute displacement of the lever measured by the laser interferometer 9 can be used to further correct the calculation of the electrostatic force, ensuring 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 is expressed by the following formula:

[0086] F e =α·U(t) 2 ;

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

[0088] In some embodiments, to improve measurement accuracy, the proportionality constant α can be corrected by combining experimental calibration data. Generally, α is affected by the number of teeth, the inter-tooth distance, and the dielectric properties of the material of the electrostatic comb body 3; therefore, 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 fitting using the least squares method to reduce systematic 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 Here, N represents the electrostatic force, which is the force generated due to the electrostatic effect. N is the number of teeth on the electrostatic comb body 3, ε0 is the vacuum permittivity, t is the comb width, d is the distance between the comb teeth, and U is the voltage applied to the electrostatic comb body 3. The change in electrostatic force before and after the experimental droplet completely detaches can be calculated using the following formula:

[0092]

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

[0094] Under normal circumstances, the adhesion force of experimental droplet 5 can be calculated from the change in electrostatic force, that is:

[0095] F a =ΔF e ;

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

[0097] In some embodiments, to reduce the impact of environmental factors on measurement accuracy, corrections can be made using data from the laser interferometer 9. Specifically, the laser interferometer 9 can monitor minute changes in the lever's tilt angle and, using the force balance formula of the lever system, correct for calculation errors in electrostatic force. Alternatively, the displacement θ measured by the laser interferometer 9 can be used, combined with the lever's geometric parameters L, to calculate the corresponding torque compensation value, thereby obtaining more accurate adhesion force measurement results.

[0098] In some embodiments, the relationship model between electrostatic force and voltage can be optimized by incorporating historical experimental data. For example, by measuring the changes in 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 force of the experimental droplet 5 is measured by utilizing electrostatic force to regulate the balance of the lever system and precisely controlling the contact and separation process between the experimental droplet 5 and the superhydrophobic surface 6. First, an initial voltage is applied to both ends of the electrostatic comb body 3, generating electrostatic force that causes the lever to lose balance. The position of the counterweight 2 is then adjusted to restore the lever to a horizontal position, establishing initial system equilibrium. Subsequently, the nano-micro-stage 7 is controlled to drive the superhydrophobic surface 6 downwards with a fixed feed rate, allowing it to slowly contact the experimental droplet 5, and then upwards, achieving gradual separation of the droplet 5. Throughout the process, the position of the counterweight 2 remains unchanged; only the voltage across the electrostatic comb body 3 is adjusted to maintain the lever's balance, and the voltage changes at different positions are recorded in real time. Through multiple experiments, the average value of the adhesion force of the experimental droplet 5 under each applied voltage is taken as the final measurement result.

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

Claims

1. An adhesive force measuring device based on the lever balance method, characterized in that, This includes a lever system, an electrostatic comb system, a droplet adhesion measurement system, and a measurement and control system; The lever system includes a pivot (1), a lever, and a 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 includes an electrostatic comb body (3), the top of which is mounted on the bottom of a lever, and an electric displacement stage (4) is fixedly connected to the bottom of the electrostatic comb body (3). The droplet adhesion measurement system includes a superhydrophobic surface (6) and a nano-micro stage (7). The superhydrophobic surface (6) is positioned directly above one end of a lever. The superhydrophobic surface (6) is used to precisely control the contact position between the superhydrophobic surface (6) and the experimental droplet (5) via the nano-micro stage (7). The experimental droplet (5) is positioned between the lever and the superhydrophobic surface (6). The measurement and control system includes a plane mirror (10), a laser interferometer (9), and an tilt sensor (8). The plane mirror (10) is located on the top of the lever, the laser interferometer (9) is located directly above the plane mirror (10) in a horizontal state, and the tilt sensor (8) is installed on the top of the lever to monitor the tilt 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 provided at the top groove of one end of the lever near the electrostatic comb body (3), and the size of the circular paper piece matches that of the experimental droplet (5).

3. A method for measuring adhesive force based on the lever balance method, applied to the adhesive force measuring device based on the lever balance method as described in any one of claims 1-2, characterized in that, Includes the following steps: An experimental system was constructed, including a lever, a pivot (1), a counterweight (2), an electrostatic comb body (3), an electric displacement stage (4), a nano-micro stage (7), a superhydrophobic surface (6), an tilt sensor (8), a laser interferometer (9), a plane mirror (10), and a voltage loading device. Experimental liquid droplets (5) were added and the position of the counterweight (2) was adjusted so that the lever was in an initial equilibrium state. An initial voltage is applied to both ends of the electrostatic comb body (3) to generate electrostatic force. The counterweight (2) is adjusted to make the lever reach balance again, and the initial electrostatic force is recorded. The nano-micro stage (7) is controlled to move downward with a fixed feed rate so that the superhydrophobic surface (6) slowly contacts the experimental droplet (5). During this period, the position of the counterweight (2) remains unchanged, and the lever is kept in balance by adjusting the voltage of the electrostatic comb body (3). After the experimental droplet (5) comes into contact, the nano-micro stage (7) is controlled to move upward in the opposite direction, so that the experimental droplet (5) gradually detaches from the superhydrophobic surface (6), the voltage of the electrostatic comb body (3) is continuously adjusted to maintain the lever balance, 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 obtained 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 method for measuring adhesive force based on the lever balance method according to claim 3, characterized in that, The steps for setting up the experimental system include: Fix the lever to the pivot (1), connect the electrostatic comb body (3) to one end of the lever and the counterweight (2) to the other end, and adjust the counterweight (2) to initially balance the lever; An angle sensor (8) is installed at one end of the lever near the electrostatic comb body (3) to detect the initial balance state, and a laser interferometer (9) is used to vertically incident on the plane mirror (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 the electric displacement stage (4) to align it with the comb teeth below the lever and to an appropriate meshing distance. At the same time, the superhydrophobic surface (6) is adjusted to be directly above the experimental droplet (5) by the nano-micro stage (7) to ensure that the experimental system is in an initial equilibrium state.

5. The method for measuring adhesive force based on the lever balance method according to claim 4, characterized in that, A circular piece of paper 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 superhydrophobic material is sprayed around it. After drying, the paper is removed, the experimental droplet (5) is added to the groove, and the lever is restored to balance by adjusting the counterweight (2).

6. The method for measuring adhesive force 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 the calibration curve of the experimental system. The voltage loading device includes a voltage regulator and a micro-current detection device for precisely controlling the application of the electrostatic force.

7. The method for measuring adhesive force based on the lever balance method according to claim 3, characterized in that, The displacement feed of the nano-micro stage (7) is 0.01 to 10 micrometers / second. The feed is finely adjusted by a precise stepping control system to ensure precise control of the contact process between the superhydrophobic surface (6) and the experimental droplet (5).

8. The method for measuring adhesive force based on the lever balance method according to claim 3, characterized in that, The change in power is dynamically calculated by the voltage change at both ends of the electrostatic comb body (3). The dynamic calculation includes obtaining the accurate adhesion force value by using numerical integration 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 stage (7), to ensure high accuracy and fast feedback of the data.

9. The method for measuring adhesive force based on the lever balance method according to claim 8, characterized in that, The formula for calculating the relationship between voltage and electrostatic force is as follows: ； in, The change in electrostatic force This is the proportionality constant between voltage and electrostatic force, which usually needs to be obtained through experimental calibration. The voltage across the two ends of the electrostatic comb body (3) is... The variable is time, representing a specific moment in the experimental process.

10. The method for measuring adhesive force 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. Combined with the data from the tilt sensor (8), the microprocessor calculates the angle deviation of the lever and uses this as a feedback signal to dynamically adjust the voltage of the electrostatic comb body (3) to ensure that the lever remains balanced throughout the measurement process and improves the measurement accuracy.

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