A droplet directional movement experimental device and method based on super-hydrophobic motion control

Abstract

The invention provides a droplet directional movement experimental device and method based on super-hydrophobic motion control, belonging to the technical field of droplet directional movement experiments. The technical problem to be solved is: providing a droplet directional movement experimental device structure and an experimental method based on super-hydrophobic motion control. The technical solution adopted is: an X-axis limiting mechanism is installed on a Y-axis limiting mechanism, and the X-axis limiting mechanism and the Y-axis limiting mechanism are arranged horizontally at 90 degrees to each other; a servo motor is provided at one end of a base plate of the X-axis limiting mechanism, an output end of the servo motor is connected to a ball screw after being connected in series with an encoder, a limiting boss is movably provided on the ball screw, a pair of trapezoidal guide rails are also provided on both sides of the base plate in parallel with the ball screw, and a slider is movably provided on the trapezoidal guide rails; a test sample is installed on the limiting boss, and a super-hydrophobic surface is fixedly installed on the test sample; the invention is applied to droplet directional movement experiments.

Description

Technical Field

[0001] The invention provides a droplet directional movement experimental device and method based on super-hydrophobic motion control, belonging to the technical field of droplet directional movement experiments. Background Art

[0002] Compared with the traditional droplet transfer methods of microfluidic chips and pipettes, the method of using the asymmetric periodic motion of super-hydrophobic surfaces to achieve droplet transfer has the advantages of high control accuracy, wide applicable droplet range, free transfer path and prevention of cross-contamination between interfaces. Therefore, it has received increasing attention in the fields of biomedicine and chemical analysis. However, the influence of the vibration characteristics of super-hydrophobic surfaces, including the direction, amplitude, frequency, speed and acceleration curve of vibration on the movement forms such as peristalsis, rolling, bouncing and their speed of droplets, needs further experimental verification. At present, there is no research method based on the influence of asymmetric periodic motion characteristics on the directional movement behavior of droplets on super-hydrophobic surfaces, and there is a lack of corresponding experimental equipment. Therefore, the design and proposal of an experimental device and method that can exert arbitrarily controllable time-speed on super-hydrophobic surfaces have important scientific significance and application value. Summary of the Invention

[0003] In order to overcome the deficiencies in the prior art, the present invention aims to provide a droplet directional movement experimental device structure and an experimental method based on super-hydrophobic motion control.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows: a droplet directional movement experimental device based on super-hydrophobic motion control, comprising an X-axis restriction mechanism and a Y-axis restriction mechanism, wherein the X-axis restriction mechanism is mounted on the Y-axis restriction mechanism, and the X-axis restriction mechanism and the Y-axis restriction mechanism are arranged horizontally at 90 degrees to each other;

[0005] The X-axis limiting mechanism includes a first base plate, a first servo motor is provided at one end of the first base plate, an output end of the first servo motor is connected in series with a first encoder and then connected to a first ball screw, a first limiting boss is movably provided on the first ball screw, a pair of first trapezoidal guide rails are also provided on both sides of the first base plate in parallel with the first ball screw, and a first slider is movably provided on the first trapezoidal guide rails;

[0006] A test sample is installed on the first limiting boss, both sides of the test sample are connected and fixed to the first slider, and a super-hydrophobic surface is fixed on the test sample by screws or bolts through the provided fixing holes and spring sleeve holes;

[0007] The Y-axis limiting mechanism includes a second base plate, a second servo motor is provided at one end of the second base plate, an output end of the second servo motor is connected in series with a second encoder and then connected to a second ball screw, a second limiting boss is movably provided on the second ball screw, a pair of second trapezoidal guide rails are also provided on both sides of the second base plate in parallel with the second ball screw, and a second slider is movably provided on the second trapezoidal guide rails;

[0008] The upper side of the second limiting boss is connected and fixed to the center position of the first base plate, and the upper side of the second sliding block is connected and fixed to the bottom of the first base plate;

[0009] A plurality of Z-axis limiting mechanisms are also provided around the bottom of the second base plate;

[0010] A Z-axis compensation mechanism is also provided at the center of the bottom of the second base plate, and the Z-axis compensation mechanism includes a solenoid valve and a cylinder;

[0011] The first servo motor, the first encoder, the second servo motor, the second encoder, the Z-axis limiting mechanism, the solenoid valve, and the control end of the cylinder are all connected to the electromagnetic force control device.

[0012] The Z-axis limiting mechanism includes a vertically arranged hydraulic cylinder housing, an oil inlet hole and an oil outlet hole are provided on the side wall of the hydraulic cylinder housing, a telescopic rod is movably provided at the output end of the hydraulic cylinder housing, an optical shaft sleeve hole is provided at the extended end of the telescopic rod, and the optical shaft sleeve hole is hinged to the fixed ear provided at the bottom of the second base plate through a pin;

[0013] A hydraulic cylinder is provided inside the hydraulic cylinder housing, and a one-way valve is also provided inside the hydraulic cylinder;

[0014] A frustum base is provided at the bottom of the hydraulic cylinder housing, and the frustum base is placed on a test bench during use.

[0015] The solenoid valve includes a valve body, an output end of the valve body is connected to a valve core via an adjusting screw, both ends of the valve core are provided with an electromagnet coil, and a valve cover is provided at an extended end of the valve core;

[0016] A guide component and a guide spring are also provided on the outer side of the adjusting screw;

[0017] The cylinder comprises a cylinder barrel, a piston rod is provided inside the cylinder barrel, a driving end of the piston rod is movably connected to an end cover via a piston, and a sealing ring and a buffer mechanism are further provided on the inner side of the end cover;

[0018] The extended end of the piston rod contacts the center position of the bottom of the second bottom plate, and an adjustment spring is provided between the cylinder and the second bottom plate;

[0019] Both ends of the piston rod are connected to the electromagnet coil respectively.

[0020] When the solenoid valve is in use, the air pressure on the valve core, the thrust of the valve core compression spring, the thrust of the return spring and the inherent friction force are adjusted in real time under the action of the electromagnet coil, the guide component and the adjusting screw.

[0021] When the cylinder is in use, the buffer mechanism, piston and piston rod arranged inside are controlled by the electromagnetic valve, so that the piston rod can output outward thrust smoothly and obtain a nonlinear periodic speed.

[0022] The first servo motor, the first encoder, the second servo motor, and the second encoder jointly complete the collection and feedback of the water droplet displacement data on the super-hydrophobic surface;

[0023] The motion data collected by the sensors provided on the first ball screw and the second ball screw are adaptively adjusted by the algorithm program built into the electromagnetic force control device according to the needs of the motion thread.

[0024] The sensor specifically includes a force sensor signal acquisition module, a force sensor signal amplification module, and a communication module;

[0025] The algorithm program built into the electromagnetic force control device is specifically a PID closed-loop regulation control algorithm and a PWM pulse width modulation algorithm.

[0026] The super-hydrophobic surface is specifically a symmetrical micro-pillar array structure, or a homogeneous and isotropic random micro-nano structure;

[0027] During the experiment, the superhydrophobic surface was modified so that the droplets were in a Cassie state on the superhydrophobic surface.

[0028] Specifically, four Z-axis limiting mechanisms are provided.

[0029] An experimental method for directional droplet movement based on superhydrophobic motion control includes the following experimental steps:

[0030] Step 1: Set the experimental device to its initial position:

[0031] Move the test sample to the middle of the first base plate, move the first base plate to the middle of the second base plate, and adjust the telescopic height of each hydraulic cylinder housing so that the test sample remains horizontal;

[0032] Fix the superhydrophobic surface to the test sample with bolts and level it;

[0033] Step 2: Preload the superhydrophobic surface:

[0034] The electromagnetic force control device controls the start of the first and second servo motors. After removing the influence of the self-gravity of the test sample and the super-hydrophobic surface, the calculated correction value is brought in to complete the unidirectional movement of the test sample under the action of the servo motor and the X and Y axis limit mechanisms. The displacement data is collected and fed back for recording and debugging.

[0035] The electromagnetic force control device controls the action of the solenoid valve cylinder, and uses the cylinder to adjust the air source pressure to push the test sample to adjust the acceleration, complete the unidirectional movement of the test sample under the action of the cylinder and the solenoid valve, complete the collection and feedback of the displacement data, and perform recording and debugging;

[0036] Step 3: Use a high-speed camera to capture the time-displacement image of the droplet on the super-hydrophobic surface to observe the dynamic characteristics of the droplet and the velocity of the center of mass;

[0037] Step 4: Establish the relationship between the vibration characteristics of the super-hydrophobic surface and the dynamic characteristics and center of mass velocity of the droplet, and obtain the relationship between the asymmetric vibration of the super-hydrophobic surface and the directional movement performance of the droplet.

[0038] The beneficial effects of the present invention compared to the prior art are as follows: the experimental device provided by the present invention can apply asymmetric periodic vibrations to the super-hydrophobic surface by setting a limiting mechanism in the corresponding direction, so as to realize the creeping and rolling of the droplets on the surface, and thus realize the precise control of the directional movement of the droplets. In conjunction with a high-speed camera, the dynamic situation of the droplets can be observed in real time, and the dynamic process can be recorded in real time. The entire device has a simple and compact structure and can be conveniently placed on a microscope stage or in a test environment with limited space, so as to realize experiments and research on the directional movement of droplets on super-hydrophobic surfaces. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The present invention will be further described below with reference to the accompanying drawings:

[0040] Figure 1 Schematic diagram of the structure of the experimental device of the present invention;

[0041] Figure 2 for Figure 1 Side view of

[0042] Figure 3 Schematic diagram of the structure of the X-axis limiting mechanism of the present invention;

[0043] Figure 4 Schematic diagram of the structure of the Y-axis limiting mechanism of the present invention;

[0044] Figure 5 Schematic diagram of the structure of the Z-axis limiting mechanism of the present invention;

[0045] Figure 6 It is a structural schematic diagram of the solenoid valve of the present invention;

[0046] Figure 7 It is a structural schematic diagram of the cylinder of the present invention;

[0047] In the figure: 1 is the X-axis limiting mechanism, 2 is the Y-axis limiting mechanism, 3 is the Z-axis limiting mechanism, 4 is the solenoid valve, 5 is the cylinder, and 6 is the super-hydrophobic surface;

[0048] 100 is the first base plate, 101 is the first servo motor, 102 is the first encoder, 103 is the first trapezoidal guide rail, 104 is the first ball screw, 105 is the first slider, 106 is the first limiting boss, 107 is the test sample, 108 is the fixing hole, and 109 is the spring sleeve hole;

[0049] 200 is the second base plate, 201 is the second servo motor, 202 is the second encoder, 203 is the second trapezoidal guide rail, 204 is the second ball screw, 205 is the second slider, 206 is the second limiting boss, and 207 is the fixing ear;

[0050] 300 is the hydraulic cylinder housing, 301 is the optical shaft sleeve hole, 302 is the telescopic rod, 303 is the oil inlet hole, 304 is the hydraulic cylinder, 305 is the oil outlet hole, 306 is the one-way valve, and 307 is the frustum base;

[0051] 401 is the valve cover, 402 is the electromagnet coil, 403 is the valve core, 404 is the guide spring, 405 is the guide component, 406 is the adjusting screw, and 407 is the valve body;

[0052] 501 is the end cover, 502 is the sealing ring, 503 is the buffer mechanism, 504 is the piston, 505 is the piston rod, 506 is the cylinder, and 507 is the adjustment spring. DETAILED DESCRIPTION

[0053] like Figures 1 to 7 As shown, the present invention provides an experimental device and method for realizing directional movement of micro-nano droplets based on asymmetric periodic motion of a super-hydrophobic surface. The provided experimental device can apply asymmetric periodic vibration with arbitrarily controllable frequency, vibration mode, time-velocity curve and vibration direction to the super-hydrophobic surface, so as to study the above-mentioned vibration characteristics and the geometric and chemical properties of the super-hydrophobic surface microstructure, as well as the influence of parameters such as droplet size, density and surface tension on the directional movement performance of droplets.

[0054] The experimental device provided by the present invention can apply asymmetric periodic vibration to a super-hydrophobic surface to achieve creeping and rolling of droplets on the surface, thereby achieving precise control of the directional movement of the droplets. By providing three vibration adjustment mechanisms in mutually perpendicular directions, it is ensured that the super-hydrophobic surface can be simultaneously subjected to vibration in three directions, thereby ensuring that the motion trajectory of the droplets forms an arbitrary curve in three-dimensional space: when X-direction vibration is applied by the X-axis limiting movement mechanism, the droplets creep or roll along the X-direction on the super-hydrophobic surface; when X-direction vibration is applied by the X-axis limiting movement mechanism and Y-direction vibration is applied by the Y-axis limiting movement mechanism at the same time, the droplets synthesize an arbitrary curve in the XY plane; when X-direction vibration is applied by the X-axis limiting movement mechanism, the Y-axis limiting movement mechanism and the Z-axis limiting movement mechanism at the same time, the droplets move along any controllable spatial curve in three-dimensional space.

[0055] The present invention utilizes the relevant classification of kinematic pairs to extract the main motion category, limit and reduce the influence of other motions, and can independently apply precise X-, Y- and Z-direction vibrations.

[0056] The time-displacement curves of the loads in the X, Y, and Z directions within one cycle provided by the present invention can be arbitrarily adjusted, such as linear function, cubic function, sine function, tangent function and other odd function curves, the amplitude can be arbitrarily adjusted between 1μm and 10mm, and the frequency can be arbitrarily adjusted within the range of 100Hz to 1000Hz.

[0057] The glass slide of the present invention has good interchangeability, avoids the problem of disassembly and assembly of the experimental table when measuring different super-hydrophobic surfaces, and improves the efficiency of the test.

[0058] The present invention can be equipped with a high-speed camera to observe the dynamic situation of the droplets in real time and record the dynamic process in real time.

[0059] The processing parts of the present invention are all made of stainless steel and are chrome-plated on the surface, which ensures that the entire device has good installation and measurement accuracy.

[0060] The device of the present invention has a simple and compact structure and can be conveniently placed on a microscope stage or in a test environment with limited space.

[0061] In order to achieve the above technical effects, the structure of the droplet directional movement experimental device provided by the present invention is specifically as follows:

[0062] The experimental device includes an X-axis limiting mechanism 1 and a Y-axis limiting mechanism 2. The X-axis limiting mechanism 1 is installed on the Y-axis limiting mechanism 2, and the X-axis limiting mechanism 1 and the Y-axis limiting mechanism 2 are arranged horizontally at 90 degrees to each other.

[0063] The X-axis limiting mechanism 1 includes a first base plate 100, a first servo motor 101 is provided at one end of the first base plate 100, an output end of the first servo motor 101 is connected in series with a first encoder 102 and then connected to a first ball screw 104, a first limiting boss 106 is movably provided on the first ball screw 104, and a pair of first trapezoidal guide rails 103 are provided on both sides of the first base plate 100 in parallel with the first ball screw 104, and a first slider 105 is movably provided on the first trapezoidal guide rails 103;

[0064] A test sample 107 is mounted on the first limiting boss 106. Both sides of the test sample 107 are connected and fixed to the first slider 105. The super-hydrophobic surface 6 is fixed to the test sample 107 by screws or bolts through the fixing holes 108 and the spring sleeve holes 109.

[0065] The Y-axis limiting mechanism 2 includes a second base plate 200, a second servo motor 201 is provided at one end of the second base plate 200, an output end of the second servo motor 201 is connected in series with a second encoder 202 and then connected to a second ball screw 204, a second limiting boss 206 is movably provided on the second ball screw 204, and a pair of second trapezoidal guide rails 203 are provided on both sides of the second base plate 200 in parallel with the second ball screw 204, and a second slider 205 is movably provided on the second trapezoidal guide rails 203;

[0066] The upper side of the second limiting boss 206 is connected and fixed to the center of the first base plate 100, and the upper side of the second sliding block 205 is connected and fixed to the bottom of the first base plate 100;

[0067] Four Z-axis limiting mechanisms 3 are also provided at the bottom of the second base plate 200;

[0068] A Z-axis compensation mechanism is also provided at the center of the bottom of the second base plate 200 , and the Z-axis compensation mechanism includes a solenoid valve 4 and a cylinder 5 ;

[0069] The control ends of the first servo motor 101 , the first encoder 102 , the second servo motor 201 , the second encoder 202 , the Z-axis limiting mechanism 3 , the solenoid valve 4 , and the cylinder 5 are all connected to the electromagnetic force control device.

[0070] The Z-axis limiting mechanism 3 includes a vertically arranged hydraulic cylinder housing 300. An oil inlet hole 303 and an oil outlet hole 305 are provided on the side wall of the hydraulic cylinder housing 300. A telescopic rod 302 is movably provided at the output end of the hydraulic cylinder housing 300. An optical shaft sleeve hole 301 is provided at the extended end of the telescopic rod 302. The optical shaft sleeve hole 301 is hinged to the fixing ear 207 provided at the bottom of the second base plate 200 via a pin.

[0071] The hydraulic cylinder housing 300 is provided with a hydraulic cylinder 304 inside, and a one-way valve 306 is also provided inside the hydraulic cylinder 304;

[0072] A frustum base 307 is provided at the bottom of the hydraulic cylinder housing 300 , and the frustum base 307 is placed on a test bench during use.

[0073] The solenoid valve 4 includes a valve body 407 , the output end of which is connected to a valve core 403 via an adjusting screw 406 , an electromagnet coil 402 is provided at both ends of the valve core 403 , and a valve cover 401 is provided at the extended end of the valve core 403 ;

[0074] A guide component 405 and a guide spring 404 are further provided on the outer side of the adjusting screw 406;

[0075] The cylinder 5 includes a cylinder barrel 506, a piston rod 505 is provided inside the cylinder barrel 506, and the driving end of the piston rod 505 is movably connected to the end cover 501 through a piston 504. The inner side of the end cover 501 is also provided with a sealing ring 502 and a buffer mechanism 503;

[0076] The extended end of the piston rod 505 contacts the center of the bottom of the second base plate 200, and an adjustment spring 507 is provided between the cylinder 506 and the second base plate 200;

[0077] Both ends of the piston rod 505 are connected to the electromagnet coil 402 respectively.

[0078] The super-hydrophobic surface provided by the present invention is specifically fixed to a test sample (slide table) using screws or bolts, and a horizontal linear displacement X-axis limiting mechanism is installed on the Y-axis limiting mechanism to achieve sliding cooperation with the Y-axis limiting mechanism; the movement direction of the slider of the horizontal linear displacement X-axis limiting mechanism is the X-axis direction, the direction perpendicular to the X-axis in the plane where the upper surface of the Y-axis limiting mechanism is located is the Y-axis direction, and the direction perpendicular to the plane where the X-axis limiting mechanism and the Y-axis limiting mechanism intersect is the Z-axis direction, that is, the vertical direction; the horizontal linear displacement X-axis limiting mechanism is used to drive the test sample to move linearly along the X-axis on the Y-axis limiting mechanism;

[0079] The Z-axis limiting mechanism is mounted on the bottom of the base plate of the Y-axis limiting mechanism via an optical shaft sleeve and a pin. The X-axis limiting mechanism and the Y-axis limiting mechanism are connected and slidably coupled in both the X and Y directions via trapezoidal guide rails. The servo motor drives the ball screw to perform periodic helical rotation, thereby driving the slider to perform radial variable speed displacement. With the auxiliary restraint of the limiting boss, the top super-hydrophobic surface, driven by the slide, can perform small, limited incremental displacements, achieving passive position limiting of the planar motion of the test specimen.

[0080] The 1024-line encoder and servo motor installed in the device are combined to complete the collection and feedback of displacement data, which is convenient for test personnel to record and debug. The sensor is installed on the ball screw through the connecting guide rod and rotates with it, so that the effective motion thread here can be adjusted according to actual needs, providing a signal source for PID closed-loop regulation and control. The adaptive force control system using the electromagnetic force control device can effectively realize the joint control of the control module, drive module, controlled object and detection module. The force control process of the electromagnetic force control device adopts pulse width modulation PWM technology to realize the combined use of PID algorithm and PWM technology. After preliminary testing, the adaptive force control strategy based on the PID algorithm has fast response speed and high stability. Based on the original classical theoretical algorithm, the PID algorithm combines the force of the electromagnetic force control device on the top super-hydrophobic surface to feedback to the control system, thereby constructing and calculating different mathematical models of flat plate physical vibration, compiling corresponding algorithms, and completing precise control of the mechanical structure.

[0081] The Z-axis limiting mechanism utilizes a hydraulic telescopic sleeve. Vibration along the Z-axis allows for autonomous limit adjustment using a hydraulic cylinder. While maintaining sufficient load capacity, it can effectively achieve up and down movement, ultimately assisting the sealed hydraulic cylinder. The top super-hydrophobic surface is secured to the slide with screws or bolts through the test specimen's fixing holes. During this process, auxiliary adjustment springs, operating through the slide's four spring sleeve holes, limit movement in all directions, simultaneously providing force compensation and mitigating inertial impact.

[0082] The piston rod is fixed on the electromagnet coil. The geometric center of the base plate of the Y-axis limiting mechanism is the position where the solenoid valve controls the cylinder to act on the test sample. The four surrounding fixed loads are spring-fixed positions to prevent the test sample from tilting. This is the location where the force in the Z-axis direction is applied. All connection forms are hinged to ensure the independent action of forces in each direction. For the X-axis and Y-axis movement modes, the servo motor drive mode is used to generate displacement increments. Based on the above-mentioned 1024-line encoder and algorithm adjustment, etc., the collected information is used, and the slide is driven by the ball screw to perform variable speed movement, thereby achieving a target specific movement mode.

[0083] The basic components of the solenoid valve, including the valve cover, valve core, and valve body, are controlled by the solenoid coil, guide components, and adjustment screws to adjust the air pressure acting on the valve core, the thrust of the valve core compression spring, the thrust of the return spring, and the inherent friction in real time. By autonomously adjusting the air source pressure of the two-position, three-way solenoid valve, the target acceleration curve of the test specimen is obtained.

[0084] The end cover, sealing ring and cylinder barrel together constitute the basic structure of the cylinder. By utilizing the buffer mechanism, piston and piston rod under the control of the solenoid valve, the cylinder can output thrust outward smoothly, ensuring that the piston rod obtains a nonlinear periodic speed.

[0085] The experimental device provided by this invention utilizes four hydraulic rod support mechanisms: an X-axis limiting mechanism, a Y-axis limiting mechanism, and a Z-axis limiting mechanism. The X-axis limiting mechanism and the Y-axis limiting mechanism are responsible for high-precision positioning and stabilization of water droplets on a flat plate in the horizontal plane (i.e., the X and Y axes), allowing them to undergo variable acceleration. The Z-axis limiting mechanism serves as a passive vertical adjustment power source, controlling the extension and retraction of the telescopic rod to induce asymmetric periodic motion of the water droplets on the plate in the Z direction.

[0086] The experimental device integrates high-precision sensors (force sensor signal acquisition module, force sensor signal amplification module, external communication module, etc.) and embedded intelligent algorithms (PID closed-loop regulation control algorithm, pulse width modulation PWM technology) to monitor the movement state of water droplets on the top super-hydrophobic surface in real time, ensuring that the board moves precisely in three-dimensional space according to the predetermined path, realizing the coordination of physics and algorithms, achieving closed-loop feedback under the action of the target, and citing the adaptive force control strategy design method to complete auxiliary control.

[0087] The X-axis limiting mechanism, Y-axis limiting mechanism and Z-axis limiting mechanism provided by the present invention adopt a modular design, which is convenient for disassembly and reduces maintenance costs to a certain extent. In addition, this project adopts energy-saving and efficient hydraulic pumps and valve groups, which reduces energy consumption and noise processing. A through hole is processed on the set slide, and a circle of step surface is processed on the inner wall of the through hole. The installation, fixation and disassembly of the top super-hydrophobic surface can be achieved by screws or bolts, simplifying the operation process. The X-axis limiting mechanism, Y-axis limiting mechanism, Z-axis limiting mechanism, trapezoidal guide rail, ball screw, slider, limiting boss, slide, test sample fixing hole, spring sleeve hole, etc. used in the present invention are all made of stainless steel and chrome-plated on the surface.

[0088] The present invention selects a suitable stiffness correction coefficient in the Z-axis direction to support the auxiliary adjustment spring of the test specimen of the suspension system, and realizes the four-corner positioning of the test specimen through the spring sleeve hole, which not only avoids the instability of directly acting on the top super-hydrophobic surface, but also realizes the elastic regulation of the load force applied to the cylinder telescopic rod, effectively realizing continuous motion measurement and small deformation monitoring.

[0089] Based on the above experimental device, an experimental method for achieving directional movement of micro-nano droplets by utilizing asymmetric periodic motion of a super-hydrophobic surface is provided, which specifically includes the following experimental steps:

[0090] Step 1: Fix the experimental device: Use bolts to fix the z-axis limit mechanism of the experimental device to the vibration reduction test table. The bottom round table base and the test table are connected by strong magnetic attraction to complete the fixation of the entire experimental device.

[0091] Step 2: Prepare a super-hydrophobic surface: The super-hydrophobic surface can be a symmetrical micro-pillar array structure, a homogeneous isotropic random micro-nanostructure, or other asymmetric micro-nanostructure. After surface modification, the droplet is in a Cassie state on the super-hydrophobic surface.

[0092] Step 3: Set the initial position of the test device: move the slide to the middle of the X-axis limit mechanism, move the X-axis limit mechanism to the middle of the Y-axis limit mechanism, and adjust the Z-axis limit mechanism to keep the slide level;

[0093] Step 4: Install the super-hydrophobic surface to be tested and level it; fix the super-hydrophobic surface to be tested on the slide and fix it with the bolts in the fixing holes of the test sample.

[0094] Step 5: Determine the preload force:

[0095] The main power part of this equipment in the Z-axis direction is composed of a cylinder and a solenoid valve. The speed is affected by two factors: gas pressure and load. The acceleration is adjusted by adjusting the gas source pressure. The passive constraint part uses a Z-limiting mechanism to complete the auxiliary restriction of the unidirectional precise movement of the test sample under the action of the cylinder and solenoid valve, thereby completing the test of the target droplet by making the piston rod act on the auxiliary control device, avoiding the interference vibration and tilt caused by the uneven force distribution and elastic deformation of the adjustment spring due to direct action on the test sample.

[0096] The main driving force in the X and Y directions of this device is generated by the servo motor drive, which is affected by the algorithm control and the ball screw guide process. Compared with the Z-axis direction, after removing the influence of the self-gravity of the slide and the super-hydrophobic surface itself, the calculation correction value is again brought into play to complete the unidirectional precise movement and auxiliary restriction of the test sample under the action of the drive mechanism and the X and Y axis restriction mechanism.

[0097] The middle force-applying part is the solenoid valve controlling the cylinder's action position on the steel test sample. The four surrounding fixed loads are spring-fixed positions to prevent the test sample from tilting. Under the action of the electromagnetic force composed of the air pressure on the valve core, the thrust of the valve core compression spring, the thrust of the return spring and the friction force, the cylinder pushes the test sample to complete the variable acceleration adjustment.

[0098] For the X and Y axis limiting mechanism, the servo motor + encoder mode is adopted to realize the linkage with the cylinder + solenoid valve. The cylinder and solenoid valve are controlled as the main body to passively limit the plane movement. At the same time, the collection and feedback of the displacement data are completed to facilitate the recording and debugging of the test personnel. The effective motion thread here can be adjusted according to actual needs.

[0099] For the Z-axis limiting mechanism, a hydraulic telescopic sleeve is adopted. Through vibration in the Z-axis direction, the hydraulic cylinder is used for autonomous limit adjustment. It can effectively complete the up and down movement while having sufficient load-bearing capacity, and finally realize the auxiliary work of the sealing hydraulic cylinder.

[0100] Finally, with the cooperation of the cylinder, solenoid valve and XYZ limiting mechanism, independent control of the test sample in one direction is achieved. By adding high-precision sensors (force sensor signal acquisition module, force sensor signal amplification module, external communication module, etc.) and embedded intelligent algorithms (PID closed-loop regulation control algorithm, pulse width modulation PWM technology), complete closed-loop feedback regulation is achieved, and finally the target displacement in the three directions of XYZ - the regulation and control of motion is achieved.

[0101] Similarly, for simultaneous vibration in the X and Y directions, linkage control can be used in addition to the above steps to complete the task. Similarly, for the simultaneous application of loads in the X, Y, and Z directions, the joint control method can also be used to achieve synchronous or asynchronous control, ultimately achieving the desired effect.

[0102] Step 6: Use a high-speed camera to capture the time-displacement image of the droplet and observe the dynamic characteristics of the droplet (peristalsis, rolling, jumping, breaking, etc.) and the velocity of the center of mass;

[0103] Step 7: Establish the relationship between the super-hydrophobic surface vibration characteristics (amplitude, frequency, time-displacement curve) and the droplet dynamic characteristics (peristalsis, rolling, jumping, breaking, etc.) and center of mass velocity, reveal the mechanism of the asymmetric vibration of the super-hydrophobic surface on the directional movement of droplets, and achieve precise, efficient, non-destructive and pollution-free control of the directional movement of droplets on the super-hydrophobic surface.

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A droplet directional movement experimental device based on superhydrophobic motion control, comprising an X-axis limiting mechanism (1) and a Y-axis limiting mechanism (2), characterized in that: The X-axis limiting mechanism (1) is mounted on the Y-axis limiting mechanism (2), and the X-axis limiting mechanism (1) and the Y-axis limiting mechanism (2) are arranged horizontally at 90 degrees to each other; The X-axis limiting mechanism (1) comprises a first base plate (100), a first servo motor (101) is provided at one end of the first base plate (100), an output end of the first servo motor (101) is connected in series with a first encoder (102) and then connected to a first ball screw (104), a first limiting boss (106) is movably provided on the first ball screw (104), a pair of first trapezoidal guide rails (103) are also provided on both sides of the first base plate (100) in parallel with the first ball screw (104), and a first slider (105) is movably provided on the first trapezoidal guide rail (103); A test sample (107) is mounted on the first limiting boss (106), two sides of the test sample (107) are connected and fixed to the first slider (105), and a super-hydrophobic surface (6) is mounted and fixed on the test sample (107) by screws or bolts through the provided fixing holes (108) and spring sleeve holes (109); The Y-axis limiting mechanism (2) comprises a second base plate (200), a second servo motor (201) is provided at one end of the second base plate (200), an output end of the second servo motor (201) is connected in series with a second encoder (202) and then connected to a second ball screw (204), a second limiting boss (206) is movably provided on the second ball screw (204), a pair of second trapezoidal guide rails (203) are also provided on both sides of the second base plate (200) in parallel with the second ball screw (204), and a second slider (205) is movably provided on the second trapezoidal guide rail (203); The upper side of the second limiting boss (206) is connected and fixed to the center position of the first base plate (100), and the upper side of the second sliding block (205) is connected and fixed to the bottom of the first base plate (100); A plurality of Z-axis limiting mechanisms (3) are also provided around the bottom of the second bottom plate (200); A Z-axis compensation mechanism is also provided at the center of the bottom of the second base plate (200), and the Z-axis compensation mechanism includes a solenoid valve (4) and a cylinder (5); The control ends of the first servo motor (101), the first encoder (102), the second servo motor (201), the second encoder (202), the Z-axis limiting mechanism (3), the electromagnetic valve (4), and the cylinder (5) are all connected to the electromagnetic force control device; The solenoid valve (4) comprises a valve body (407), the output end of the valve body (407) is connected to the valve core (403) via an adjusting screw (406), and electromagnet coils (402) are provided at both ends of the valve core (403), and a valve cover (401) is provided at the extended end of the valve core (403); A guide component (405) and a guide spring (404) are also provided on the outer side of the adjusting screw (406); The cylinder (5) comprises a cylinder barrel (506), a piston rod (505) is provided inside the cylinder barrel (506), a driving end of the piston rod (505) is movably connected to the end cover (501) via a piston (504), and a sealing ring (502) and a buffer mechanism (503) are further provided on the inner side of the end cover (501); The extended end of the piston rod (505) contacts the center position of the bottom of the second base plate (200), and an adjustment spring (507) is provided between the cylinder (506) and the second base plate (200); Both ends of the piston rod (505) are connected to the electromagnet coil (402) respectively.

2. The droplet directional movement experimental device based on super-hydrophobic motion control according to claim 1, characterized in that: The Z-axis limiting mechanism (3) comprises a vertically arranged hydraulic cylinder housing (300), an oil inlet hole (303) and an oil outlet hole (305) being provided on a side wall of the hydraulic cylinder housing (300), a telescopic rod (302) being movably provided at the output end of the hydraulic cylinder housing (300), an optical shaft sleeve hole (301) being provided at the extended end of the telescopic rod (302), and the optical shaft sleeve hole (301) being hinged to a fixing ear (207) provided at the bottom of the second base plate (200) via a pin; A hydraulic cylinder (304) is provided inside the hydraulic cylinder housing (300), and a one-way valve (306) is also provided inside the hydraulic cylinder (304); A truncated cone base (307) is provided at the bottom of the hydraulic cylinder housing (300). When in use, the truncated cone base (307) is placed on a test bench.

3. The droplet directional movement experimental device based on super-hydrophobic motion control according to claim 2, characterized in that: When the solenoid valve (4) is in use, the air pressure, the thrust of the valve core compression spring, the thrust of the return spring, and the inherent friction force of the valve core (403) are adjusted in real time under the action of the electromagnet coil (402), the guide component (405), and the adjusting screw (406).

4. The droplet directional movement experimental device based on super-hydrophobic motion control according to claim 3, characterized in that: When the cylinder (5) is in use, the buffer mechanism (503), the piston (504), and the piston rod (505) provided therein are controlled by the solenoid valve (4), so that the piston rod (505) can output an outward thrust in a stable manner and can obtain a nonlinear periodic speed.

5. The droplet directional movement experimental device based on super-hydrophobic motion control according to claim 1, characterized in that: The first servo motor (101), the first encoder (102), the second servo motor (201), and the second encoder (202) jointly complete the collection and feedback of water droplet displacement data on the super-hydrophobic surface (6); The motion data collected by sensors provided on the first ball screw (104) and the second ball screw (204) are adaptively adjusted according to the needs of the motion thread by an algorithm program built into the electromagnetic force control device.

6. The droplet directional movement experimental device based on super-hydrophobic motion control according to claim 5, characterized in that: The sensor specifically includes a force sensor signal acquisition module, a force sensor signal amplification module, and a communication module; The algorithm program built into the electromagnetic force control device is specifically a PID closed-loop regulation control algorithm and a PWM pulse width modulation algorithm.

7. The droplet directional movement experimental device based on super-hydrophobic motion control according to claim 1, characterized in that: The super-hydrophobic surface (6) is specifically a symmetrical micro-pillar array structure, or a homogeneous and isotropic random micro-nano structure; During the experiment, the super-hydrophobic surface (6) was surface-modified so that the droplets were in a Cassie state on the super-hydrophobic surface (6).

8. The droplet directional movement experimental device based on super-hydrophobic motion control according to claim 1, characterized in that: Specifically, four Z-axis limiting mechanisms (3) are provided.

9. The experimental method of the droplet directional movement experimental device based on super-hydrophobic motion control according to claim 2, characterized in that: The experimental steps include the following: Step 1: Set the experimental device to its initial position: Moving the test sample (107) to the middle of the first bottom plate (100), moving the first bottom plate (100) to the middle of the second bottom plate (200), and adjusting the telescopic height of each hydraulic cylinder housing (300) so that the test sample (107) remains horizontal; The super-hydrophobic surface (6) is fixed to the test sample (107) by bolts and leveled; Step 2: Preload the superhydrophobic surface (6): The electromagnetic force control device controls the first servo motor (101) and the second servo motor (201) to start, and after removing the influence of the self-gravity of the test sample (107) and the super-hydrophobic surface (6), a calculation correction value is brought in to complete the unidirectional movement of the test sample (107) under the action of the servo motor and the X-axis and Y-axis limiting mechanisms, and completes the collection and feedback of the displacement data, and performs recording and debugging; The electromagnetic force control device controls the action of the electromagnetic valve (4) and the cylinder (5), and the cylinder (5) adjusts the air source pressure to push the test sample (107) to adjust the acceleration, thereby completing the unidirectional movement of the test sample (107) under the action of the cylinder and the electromagnetic valve, completing the collection and feedback of the displacement data, and performing recording and debugging; Step 3: Use a high-speed camera to capture the time-displacement image of the droplet on the super-hydrophobic surface (6) to observe the dynamic characteristics of the droplet and the velocity of the center of mass; Step 4: Establish the relationship between the vibration characteristics of the super-hydrophobic surface (6) and the dynamic characteristics and center of mass velocity of the droplet, and obtain the relationship between the asymmetric vibration of the super-hydrophobic surface (6) and the directional movement performance of the droplet.

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