CN109269976B - Measuring device and measuring method for measuring friction force between solid-liquid interfaces in electric field - Google Patents
Measuring device and measuring method for measuring friction force between solid-liquid interfaces in electric field Download PDFInfo
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Abstract
The invention discloses a measuring device and a measuring method for measuring friction force of a solid-liquid interface under an electric field, comprising the following steps: transparent plastic operation cabinet, horizontal base, laser sensor, electronic displacement platform, linear type cantilever beam, high-speed camera, support frame, power and data control processing terminal. In the measuring process, along with the slow movement of the electric displacement platform, the linear cantilever beam deforms due to the friction force of the linear cantilever beam and liquid drops, and the specific value of the deformation of the linear cantilever beam in the experiment is recorded through the laser sensor, so that the friction force between solid and liquid under an electric field can be calculated. Meanwhile, the high-speed camera shoots the whole experimental process, and changes of contact angles and contact areas of the upper surface and the lower surface of the liquid drop are recorded. The measuring system has the characteristics of simplicity in operation, low cost, wide application range and high measuring precision, and can well meet the requirement of measuring the friction force between solid and liquid interfaces under an electric field.
Description
Technical Field
The invention relates to a measuring device and a measuring method for measuring solid-liquid interface friction force under an electric field, in particular to a measuring device and a measuring method for measuring micro deformation of a cantilever beam by utilizing laser, and the solid-liquid interface friction force under the electric field is calculated through the relation between the deformation of the cantilever beam and solid-liquid interface behavior.
Background
The solid-liquid interface behavior plays an extremely important role in production and life. By researching the solid-liquid interface behavior, the functions of resisting pollution, resisting icing, resisting adhesion, self-cleaning, absorbing and the like can be realized in the fields of aerospace, ship manufacturing, spinning, building, environmental protection and the like. Therefore, the research on the solid-liquid interface behavior can promote the development of basic science and can also play a great role in promoting the improvement of the technological level. With the continuous development of science and technology and the expansion of market demands, active control of solid-liquid interface behaviors has become a future development trend and research hotspot. The early research mainly changes the properties of the solid or liquid drops to meet the requirements, such as changing the solid-liquid interface behaviors, so that the super-hydrophilic or super-hydrophobic state of the solid surface is realized to meet the requirements, and the method belongs to quasi-static control of the solid-liquid interface behaviors. With the development of automation and informatization, dynamic control of solid-liquid interface behaviors is imperative. Active control of solid-liquid interface behavior by voltage is one of the most widely used of various active control modes. Such as the separation, combination and transportation of microfluidics by voltage control of microfluidics, have been widely used in analytical chemistry, biomedical, food and other fields. However, with further development of integration and miniaturization of the micro-fluid control device, the solid-liquid interface behavior on the micro-scale becomes more complex, and the stability and reliability of the system are greatly affected, so that the micro-fluid control device has become a technical bottleneck for moving from a laboratory to an application. Therefore, intensive research on solid-liquid interface behavior under an electric field becomes a hotspot and difficulty of current research.
The friction force of the solid-liquid interface is the most main acting force of the solid-liquid interface, and plays a leading role in the behavior of the solid-liquid interface. At present, friction force is usually researched by using scientific research equipment such as an inclined plate device, an atomic force microscope, a surface force instrument and the like for solid-liquid interface behaviors under microscopic scale. The inclined plate device mainly obtains the friction force of the solid-liquid interface through calculation by observing the motion rule of liquid drops on the inclined plate under the action of gravity. The method is simple to operate, visual in data, low in measurement accuracy, and the tested liquid drops are limited by various factors, such as overlarge friction force of a solid-liquid interface along with the size reduction of the liquid drops, the liquid drops cannot move on the inclined plate, and the test cannot be completed. Therefore, when the liquid drop is in a microscopic scale, a precise instrument such as an atomic force microscope, a surface force instrument and the like is generally adopted to test the friction force of a solid-liquid interface. The principle of the instrument is that a micro probe is used for contacting a solid surface covered with a water film, and the adhesion behavior of a solid-liquid interface is reflected by an electric signal when the probe contacts and separates from the solid surface. The data obtained by the measuring method is accurate, but the data reaction is not a complete solid-liquid interface behavior, but a coupling behavior between solid-liquid-solid phases, which is greatly different from the actual working condition. In addition, atomic force microscope, surface force instrument etc. belong to precision instruments, have put forward the very high requirement to operating personnel, test environment, test procedure, test sample etc. and tiny change factor can cause very big experimental error. Furthermore, the electric field force and the liquid phase environment need to be introduced to measure the friction force of the solid-liquid interface under the electric field, and the testing precision of the instrument can be reduced and the instrument can be damaged in the process. Therefore, development of a method and a device which are convenient to operate, high in measurement precision and applicable to an electric field and a liquid phase environment are needed to be developed, and the method and the device are used for accurately and rapidly measuring friction force between solid-liquid interfaces under the electric field.
Disclosure of Invention
It is an object of the present invention to address at least the above problems and/or disadvantages and to provide at least the advantages described below.
To achieve these objects and other advantages and in accordance with the purpose of the invention, there is provided a measuring apparatus for measuring friction force between solid and liquid interfaces under an electric field, comprising:
a transparent plastic operation cabinet;
the horizontal base is arranged in the transparent plastic operation cabinet;
the electric displacement platform is horizontally arranged on the horizontal base;
the horizontal copper plate is adhered to the sliding block of the electric displacement platform; an electrowetting standard experiment sample is arranged on the bonding medium above the horizontal copper plate; dripping liquid drops on the electrowetting standard experiment sample on the medium;
the linear cantilever beam is vertically arranged right above the electrowetting standard experiment sample on the medium through the horizontal support frame, and the tail end of the linear cantilever beam is contacted with the liquid drop;
the laser sensor is horizontally arranged on the side surface of the electrowetting standard experiment sample on the medium through the vertical support frame, and the laser beam of the laser sensor is vertical to the tail end of the linear cantilever beam so as to shoot the displacement condition of the linear cantilever beam; the horizontal support frame is connected to the vertical support frame and is vertical to the vertical support frame;
the high-speed camera is arranged on the horizontal base and is positioned on the other side surface of the electrowetting standard experiment sample on the medium so as to shoot the contact condition of liquid drops and the tail end of the linear cantilever beam;
the power supply is arranged on the horizontal base, the positive electrode of the power supply is electrically connected with the linear cantilever beam through a lead I, and the negative electrode of the power supply is electrically connected with the horizontal copper plate through a lead II;
the data control processing terminal is positioned outside the transparent plastic operation cabinet and is respectively connected with the electric displacement platform, the laser sensor and the high-speed camera in an electric communication way.
Preferably, the electrowetting standard test sample on the medium is adhered above the horizontal copper plate by adopting conductive gel; the outer diameter of the straight cantilever Liang Wei pure copper pipe is 0.5mm, and the inner diameter is 0.25mm; the linear cantilever beam is connected to the horizontal supporting frame through conductive gel and is perpendicular to the horizontal supporting frame.
Preferably, the electrowetting on medium standard test sample comprises: the silicon wafer, an insulating layer plated on the silicon wafer and a hydrophobic layer coated on the insulating layer and dried.
Preferably, the insulating layer is 200-400 nm of SiO 2 And the coating layer is a Teflon layer.
Preferably, the vertical support frame and the horizontal support frame have the same structure and are vertically connected; the structures of the vertical support frame and the horizontal support frame comprise:
the fixed end I and the fixed end II are arranged in parallel and are connected through two parallel linear guide rails;
the sliding block is connected to the two parallel linear guide rails in a sliding manner;
the ball screw is sequentially connected with the fixed end I, the sliding block and the fixed end II in a threaded rotation manner;
the fixed end I of the vertical support frame is connected to the horizontal base, and the fixed end I of the horizontal support frame is connected to the fixed end II of the vertical support frame; the laser sensor is connected to the sliding block of the vertical support frame; the linear cantilever beam is connected to the sliding block of the horizontal support frame through conductive gel.
Preferably, the electric displacement platform is in electric communication connection with the data control processing terminal through a displacement platform data output port; the laser sensor is in electric communication connection with the data control processing terminal through a laser data output port; the high-speed camera is in electric communication connection with the data control processing terminal through the image data output port.
The invention also provides a method for measuring the friction force between the solid and liquid interfaces under the electric field by adopting the measuring device, which comprises the following steps:
step one, adding liquid drops to the surface of an electrowetting standard test sample on a medium by using a liquid dispenser;
step two, starting a laser sensor, adjusting the position of a sliding block of a vertical support frame, focusing a laser beam at the tail end of a linear cantilever beam, and enabling the tail end of the linear cantilever beam to be in contact with liquid drops by adjusting the positions of the electric displacement platform and the sliding block of a horizontal support frame; setting the current position as the zero positions of the laser sensor and the electric displacement platform;
step three, turning on a power supply and setting a voltage value; simultaneously starting a laser sensor and a high-speed camera to record the whole experimental process; starting the electric displacement platform to move at a set speed to enable the linear cantilever beam and the liquid drop to be tested to move relatively, and stopping the movement of the electric displacement platform when the liquid drop is completely separated from the surface of the electrowetting standard experiment sample on the medium; the change condition of the linear cantilever beam along with the time displacement recorded by the laser sensor in the whole experimental process is derived through the data control processing terminal;
step four, bringing the values of the outer diameter and the inner diameter of the linear cantilever beam into the following formula:
in the formula, D is a linear cantilever Liang Waijing, D is a linear cantilever Liang Najing, and the moment of inertia I is obtained;
step five, bringing the displacement change value of the linear cantilever beam in the step three and the moment of inertia in the step four into the following formula, and calculating the magnitude of friction force:
wherein F is friction force; e is the elastic modulus of the linear cantilever beam; i is the moment of a linear cantilever Liang Guanxing; l is the length of a linear cantilever beam; Δl is the linear displacement of the linear cantilever, i.e., the displacement variation.
Preferably, the preparation method of the electrowetting on medium standard experiment sample comprises the following steps: plating the surface with SiO 2 Cutting the coated silicon wafer into 30mm standard samples, then ultrasonically cleaning the standard samples for 5min, absorbing the moisture on the surface by using absorbent paper, drying the absorbent paper, and keeping the surface clean; placing the clean sample in a desk type spin coater, and spin-coating Teflon emulsion; spin coating parameters of the table type spin coater are as follows: spin-coating for 20s at a low speed of 500 r/min; spin-coating for 30s at a high speed of 3000 r/min; and finally, placing the spin-coated experimental sample in a baking oven at 200 ℃ for baking for 3 hours, and naturally cooling the spin-coated experimental sample to obtain the electrowetting standard experimental sample on the medium.
Preferably, the volume of the liquid drop is 8-12 uL; in the third step, the voltage value is 80-120V, and the speed of the electric displacement platform is 0.01-0.02 mm/s.
The model of Beijing Jiang Yun photoelectric technology Co.Ltd of the electric displacement platform adopted by the invention is Y200TA75.
The invention at least comprises the following beneficial effects:
(1) The method of the invention does not need expensive experimental equipment, has simple calculation and high precision, and has extremely high practical value.
(2) The cantilever beam and the sample are simple to manufacture, the cost is low, and the experimenter can flexibly adjust according to actual conditions.
(3) The instrument can realize the measurement of various forces through simple adjustment, meets the electric field and liquid phase test environment, and has the advantages of simple test method, strong operability, accurate experimental result and high experimental result repeatability.
(4) The experimental process can be carried out at normal temperature and normal pressure, and special experimental environments such as dust free, constant temperature and the like are not needed; meanwhile, the detection time is short, a group of experiments can be completed in 5-7 minutes, and the experimental efficiency can be greatly improved.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.
Description of the drawings:
FIG. 1 is a schematic diagram of the overall system structure of a measuring device for measuring friction force between solid and liquid interfaces in an electric field according to the present invention;
FIG. 2 is a schematic diagram of the structure of an electrowetting-on-medium standard test sample according to the present invention;
FIG. 3 is a schematic view of the structures of the vertical support and the horizontal support according to the present invention;
FIG. 4 is a schematic diagram showing the change of the linear cantilever beam before and after the experiment of the measuring device for measuring the friction force between the solid and liquid interfaces under the electric field;
FIG. 5 is a graph of linear cantilever displacement versus time for the measuring device of the invention for measuring friction force between solid and liquid interfaces under an electric field.
The specific embodiment is as follows:
the present invention is described in further detail below with reference to the drawings to enable those skilled in the art to practice the invention by referring to the description.
It will be understood that terms, such as "having," "including," and "comprising," as used herein, do not preclude the presence or addition of one or more other elements or groups thereof.
The invention designs a measuring device and a measuring method for measuring friction force of a solid-liquid interface under an electric field. In the measuring process, along with the slow movement of the electric displacement platform, the cantilever beam deforms due to the friction force of the cantilever beam and liquid drops, and the specific value of the deformation of the cantilever beam in the experiment is recorded by the laser sensor, so that the friction force between solid and liquid can be calculated. Meanwhile, the high-speed camera shoots the whole experimental process, and changes of contact angles and contact areas of the upper surface and the lower surface of the liquid drop are recorded. In addition, the cantilever beam can also adopt materials with different mechanical properties according to the actual conditions of the experiment, so that the accuracy of the experiment can be further improved. The measuring system has the characteristics of simplicity in operation, low cost, wide application range and high measuring precision, and can well meet the requirement of measuring the friction force between solid and liquid interfaces under an electric field.
Fig. 1 shows a measurement device for measuring friction force between solid and liquid interfaces under an electric field, which comprises:
a transparent plastic operation cabinet 1;
a horizontal base 10 provided in the transparent plastic operation cabinet 1;
an electric displacement platform 2 horizontally arranged on the horizontal base 10;
a horizontal copper plate 8 adhesively arranged on the sliding block 201 of the electric displacement platform 2; an electrowetting standard experiment sample 9 is adhered to the medium above the horizontal copper plate 8; wherein, the liquid drop 7 is dropped on the electrowetting standard experiment sample 9 on the medium;
the linear cantilever beam 3 is vertically arranged right above the electrowetting standard experiment sample 9 on the medium through a horizontal support frame 13, and the tail end of the linear cantilever beam 3 is contacted with liquid drops;
the laser sensor 14 is horizontally arranged on the side surface of the electrowetting standard experiment sample 9 on the medium through the vertical support frame 12, and the laser beam of the laser sensor 14 is vertical to the tail end of the linear cantilever beam 3 so as to shoot the displacement condition of the linear cantilever beam; the horizontal support frame 13 is connected to the vertical support frame 12 and is perpendicular to the vertical support frame 12;
the high-speed camera 11 is arranged on the horizontal base 10, and the high-speed camera 11 is positioned on the other side surface of the electrowetting standard experiment sample 9 on the medium so as to shoot the contact condition of the liquid drop 7 and the tail end of the linear cantilever beam 3;
the power supply 4 is arranged on the horizontal base 10, the positive electrode of the power supply 4 is electrically connected with the linear cantilever beam 3 through a lead I5, and the negative electrode of the power supply 4 is electrically connected with the horizontal copper plate 8 through a lead II 6;
and the data control processing terminal 18 is positioned outside the transparent plastic operation cabinet 1, and the data control processing terminal 18 is respectively and electrically connected with the electric displacement platform 2, the laser sensor 14 and the high-speed camera 11.
In the technical scheme, the bottom of an electrowetting standard experiment sample on a medium is adhered to a horizontal copper plate through conductive gel, and the horizontal copper plate is arranged on a horizontal base; connecting a horizontal copper plate, a dielectric electrowetting standard experiment sample and a linear cantilever beam into a circuit; adjusting the position of the laser sensor to focus the light beam to the tail end of the linear cantilever beam; dripping liquid drops to be detected on the surface of the electrowetting standard experiment sample on the medium, so that the tail end of the linear cantilever beam contacts the liquid drops; starting a power supply to set a voltage value; starting a high-speed camera and a laser sensor to record an experimental process; and opening the electric displacement platform to move at a set speed to enable the linear cantilever beam and the liquid drop to be detected to move relatively, and recording the deformation of the linear cantilever beam through the laser sensor.
In the technical scheme, the electrowetting standard experiment sample on the medium is adhered above the horizontal copper plate by adopting conductive gel; the outer diameter of the straight cantilever Liang Wei pure copper pipe is 0.5mm, and the inner diameter is 0.25mm; the linear cantilever beam 3 is connected to the horizontal supporting frame 13 through conductive gel and is perpendicular to the horizontal supporting frame 13.
In the above technical solution, as shown in fig. 2, the electrowetting on medium standard experiment sample 9 includes: the silicon wafer (conducting layer), the insulating layer plated on the silicon wafer and the hydrophobic layer coated and dried on the insulating layer are selected as the conducting layer because the silicon wafer is the most mature semiconductor conducting material at present, and compared with other materials, the cost performance is highest.
In the technical proposal, the insulating layer is 200-400 nm SiO 2 And the coating layer is a Teflon layer. SiO is selected for use 2 The coating is due to SiO 2 The most widely used insulating materials are currently the most cost effective in terms of manufacturing technology and cost, and SiO 2 Smooth surfaceThe coating of the hydrophobic layer is not affected, and the thickness of 200-400 nm is selected because when the thickness is too small, the hydrophobic layer is easy to break down although larger contact angle change can be obtained under the condition of smaller voltage; when the thickness is too large, a larger voltage is required if a larger contact angle variation is desired; the selection interval of 200-400 nm is the best under the existing experimental conditions is obtained through consulting the related data and experiments. Teflon is used as the hydrophobic layer because Teflon has the advantages of excellent chemical stability, low price, corrosion resistance and the like, and compared with a metal vapor deposition method and a plasma chemical vapor deposition method, the coating method has the advantages of low experimental environment requirement, low cost and simple experimental operation.
In the above technical solution, the vertical support frame 12 and the horizontal support frame 13 have the same structure and are vertically connected; the structures of the vertical support frame 12 and the horizontal support frame 13 comprise:
a fixed end I19 and a fixed end II 23 which are arranged in parallel and are connected through two parallel linear guide rails 20;
a sliding block 22 slidably connected to the two parallel linear guides 20;
the ball screw 21 is sequentially connected with the fixed end I19, the sliding block 22 and the fixed end II 23 in a threaded rotation manner; by rotating the ball screw 21, the sliding block 22 can be driven to move on the linear guide rail;
the fixed end I of the vertical support frame 12 is connected to the horizontal base, and the fixed end I of the horizontal support frame 13 is connected to the fixed end II of the vertical support frame; the laser sensor 14 is connected to a sliding block of the vertical support frame 12; the linear cantilever beam 3 is connected to a sliding block of the horizontal supporting frame 13 through conductive gel.
In the above technical solution, the electric displacement platform 2 is connected in electrical communication with the data control processing terminal 18 through the displacement platform data output port 17; the laser sensor 14 is connected in electrical communication with a data control processing terminal 18 through a laser data output port 16; the high-speed camera 11 is in electric communication connection with a data control processing terminal 18 through an image data output port 15; the method mainly sets up the mode of the integrated port to output data uniformly and synchronously, so that a certain section of data and video information can be conveniently extracted for analysis.
Example 1:
the method for measuring the friction force between the solid and liquid interfaces under the electric field by adopting the measuring device comprises the following steps:
step one, adding 10uL liquid drops to the surface of an electrowetting standard test sample on a medium by using a liquid transfer device;
step two, starting a laser sensor, adjusting the position of a sliding block of a vertical support frame, focusing a laser beam at the tail end of a linear cantilever beam, and enabling the tail end of the linear cantilever beam to be in contact with liquid drops by adjusting the positions of the electric displacement platform and the sliding block of a horizontal support frame; setting the current position as the zero positions of the laser sensor and the electric displacement platform;
step three, turning on a power supply, and setting the voltage value to be 100V; simultaneously starting a laser sensor and a high-speed camera to record the whole experimental process; starting an electric displacement platform to move at the speed of 0.015mm/s to enable the linear cantilever beam and the liquid drop to be tested to move relatively, and stopping the movement of the electric displacement platform when the liquid drop is completely separated from the surface of the electrowetting standard experiment sample on the medium; the change condition of the linear cantilever beam along with the time displacement recorded by the laser sensor in the whole experimental process is derived through the data control processing terminal;
step four, bringing the values of the outer diameter and the inner diameter of the linear cantilever beam into the following formula:
in the formula, D is a linear cantilever Liang Waijing of 0.5mm, D is a linear cantilever Liang Najing of 0.25mm, and the moment of inertia I=2.89×10 is obtained -15 m 4 ；
Step five, bringing the displacement change value of the linear cantilever beam in the step three and the moment of inertia in the step four into the following formula, and calculating the magnitude of friction force:
the elastic modulus E=101 GPa of the linear cantilever beam in the formula; linear cantilever Liang Guanxing moment i=2.89×10 - 15 m 4 The method comprises the steps of carrying out a first treatment on the surface of the The length l=90 mm of the linear cantilever beam; linear displacement Δl=0.257 mm of the linear cantilever beam, i.e. the displacement variation (i.e. the displacement difference in fig. 5 with the coil); friction f=324 μn.
In the above embodiment 1, the preparation method of the electrowetting on medium standard test sample is as follows: plating the surface with SiO 2 Cutting the coated silicon wafer into 30mm standard samples, then ultrasonically cleaning the standard samples for 5min, absorbing the moisture on the surface by using absorbent paper, drying the absorbent paper, and keeping the surface clean; placing the clean sample in a desk type spin coater, and spin-coating Teflon emulsion; spin coating parameters of the table type spin coater are as follows: spin-coating for 20s at a low speed of 500 r/min; spin-coating for 30s at a high speed of 3000 r/min; and finally, placing the spin-coated experimental sample in a baking oven at 200 ℃ for baking for 3 hours, and naturally cooling the spin-coated experimental sample to obtain the electrowetting standard experimental sample on the medium.
Although embodiments of the present invention have been disclosed above, it is not limited to the details and embodiments shown and described, it is well suited to various fields of use for which the invention would be readily apparent to those skilled in the art, and accordingly, the invention is not limited to the specific details and illustrations shown and described herein, without departing from the general concepts defined in the claims and their equivalents.
Claims (6)
1. A measurement device for measure friction force between solid-liquid interface under electric field, characterized by comprising:
a transparent plastic operation cabinet;
the horizontal base is arranged in the transparent plastic operation cabinet;
the electric displacement platform is horizontally arranged on the horizontal base;
the horizontal copper plate is adhered to the sliding block of the electric displacement platform; an electrowetting standard experiment sample is arranged on the bonding medium above the horizontal copper plate; dripping liquid drops on the electrowetting standard experiment sample on the medium;
the linear cantilever beam is vertically arranged right above the electrowetting standard experiment sample on the medium through the horizontal support frame, and the tail end of the linear cantilever beam is contacted with the liquid drop;
the laser sensor is horizontally arranged on the side surface of the electrowetting standard experiment sample on the medium through the vertical support frame, and the laser beam of the laser sensor is vertical to the tail end of the linear cantilever beam so as to shoot the displacement condition of the linear cantilever beam; the horizontal support frame is connected to the vertical support frame and is vertical to the vertical support frame;
the high-speed camera is arranged on the horizontal base and is positioned on the other side surface of the electrowetting standard experiment sample on the medium so as to shoot the contact condition of liquid drops and the tail end of the linear cantilever beam;
the power supply is arranged on the horizontal base, the positive electrode of the power supply is electrically connected with the linear cantilever beam through a lead I, and the negative electrode of the power supply is electrically connected with the horizontal copper plate through a lead II;
the data control processing terminal is positioned outside the transparent plastic operation cabinet and is respectively in electric communication connection with the electric displacement platform, the laser sensor and the high-speed camera;
the electrowetting standard experiment sample on the medium is adhered above the horizontal copper plate by adopting conductive gel; the outer diameter of the straight cantilever Liang Wei pure copper pipe is 0.5mm, and the inner diameter of the straight cantilever Liang Wei pure copper pipe is 0.25mm; the linear cantilever beam is connected to the horizontal support frame through conductive gel and is vertical to the horizontal support frame;
the electrowetting on medium standard test sample comprises: the silicon wafer, an insulating layer plated on the silicon wafer and a hydrophobic layer coated on the insulating layer and dried;
the method for measuring the friction force between the solid and liquid interfaces under the electric field by adopting the measuring device comprises the following steps:
step one, adding liquid drops to the surface of an electrowetting standard test sample on a medium by using a liquid dispenser;
step two, starting a laser sensor, adjusting the position of a sliding block of a vertical support frame, focusing a laser beam at the tail end of a linear cantilever beam, and enabling the tail end of the linear cantilever beam to be in contact with liquid drops by adjusting the positions of the electric displacement platform and the sliding block of a horizontal support frame; setting the current position as the zero positions of the laser sensor and the electric displacement platform;
step three, turning on a power supply and setting a voltage value; simultaneously starting a laser sensor and a high-speed camera to record the whole experimental process; starting the electric displacement platform to move at a set speed to enable the linear cantilever beam and the liquid drop to be tested to move relatively, and stopping the movement of the electric displacement platform when the liquid drop is completely separated from the surface of the electrowetting standard experiment sample on the medium; the change condition of the linear cantilever beam along with the time displacement recorded by the laser sensor in the whole experimental process is derived through the data control processing terminal;
step four, bringing the values of the outer diameter and the inner diameter of the linear cantilever beam into the following formula:
in the formulaDIs a cantilever Liang Waijing of the type of a straight line,dfor linear cantilever Liang Najing, the moment of inertia is obtainedI；
Step five, bringing the displacement change value of the linear cantilever beam in the step three and the moment of inertia in the step four into the following formula, and calculating the magnitude of friction force:
in the formulaFIs friction force;Ethe elastic modulus of the cantilever beam is linear;Ia linear cantilever Liang Guanxing moment;Lthe length of the cantilever beam is linear;the linear displacement of the linear cantilever beam, namely the displacement change value.
2. The device for measuring friction force between solid and liquid interfaces in an electric field according to claim 1, wherein the insulating layer is 200-400 nm of SiO 2 And the coating layer is a Teflon layer.
3. The device for measuring the friction force between solid and liquid interfaces in an electric field according to claim 1, wherein the vertical supporting frame and the horizontal supporting frame have the same structure and are vertically connected; the structures of the vertical support frame and the horizontal support frame comprise:
the fixed end I and the fixed end II are arranged in parallel and are connected through two parallel linear guide rails;
the sliding block is connected to the two parallel linear guide rails in a sliding manner;
the ball screw is sequentially connected with the fixed end I, the sliding block and the fixed end II in a threaded rotation manner;
the fixed end I of the vertical support frame is connected to the horizontal base, and the fixed end I of the horizontal support frame is connected to the fixed end II of the vertical support frame; the laser sensor is connected to the sliding block of the vertical support frame; the linear cantilever beam is connected to the sliding block of the horizontal support frame through conductive gel.
4. The device for measuring the friction force between solid and liquid interfaces in an electric field according to claim 1, wherein the electric displacement platform is in electric communication connection with the data control processing terminal through a displacement platform data output port; the laser sensor is in electric communication connection with the data control processing terminal through a laser data output port; the high-speed camera is in electric communication connection with the data control processing terminal through the image data output port.
5. The device for measuring friction force between solid and liquid interfaces under an electric field according to claim 1, wherein the electrowetting on medium standard test sampleThe preparation method of (2) comprises the following steps: plating the surface with SiO 2 Cutting the coated silicon wafer into 30mm standard samples, then carrying out ultrasonic cleaning on the standard samples for 5min, absorbing the moisture on the surface by using absorbent paper, drying the absorbent paper, and keeping the surface clean; placing the clean sample in a desk type spin coater, and spin-coating Teflon emulsion; spin coating parameters of the table type spin coater are as follows: spin-coating 20s at a low speed of 500 r/min; spin-coating 30s at a high speed of 3000 r/min; and finally, placing the spin-coated experimental sample in a baking oven at 200 ℃ for baking 3h, and naturally cooling to obtain the electrowetting standard experimental sample on the medium.
6. The device for measuring friction force between solid and liquid interfaces in an electric field according to claim 1, wherein the volume of the liquid drop is 8-12uLThe method comprises the steps of carrying out a first treatment on the surface of the In the third step, the voltage value is 80-120V, and the speed of the electric displacement platform is 0.01-0.02 mm/s.
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| CN201811363360.2A CN109269976B (en) | 2018-11-16 | 2018-11-16 | Measuring device and measuring method for measuring friction force between solid-liquid interfaces in electric field |
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| CN201811363360.2A CN109269976B (en) | 2018-11-16 | 2018-11-16 | Measuring device and measuring method for measuring friction force between solid-liquid interfaces in electric field |
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| CN109269976B true CN109269976B (en) | 2023-10-03 |
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| CN110487679B (en) * | 2019-07-30 | 2021-07-20 | 武汉大学 | Device for measuring friction force of liquid drop on solid surface |
| CN111579430B (en) * | 2020-05-12 | 2023-11-10 | 宁波工程学院 | Coating uniformity testing device and testing method based on droplet motion trail |
| CN112014234B (en) * | 2020-08-26 | 2022-06-28 | 西南科技大学 | Device for measuring normal and tangential ice adhesion strength of material surface |
| CN113702281A (en) * | 2021-08-25 | 2021-11-26 | 重庆齿轮箱有限责任公司 | Solid-liquid interface adhesion force testing method and system |
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