阅读说明：本技术 一种液体相对介电常数的测量方法及系统 (Method and system for measuring relative dielectric constant of liquid ) 是由 方海生 陈浩 聂圻春 高仙仙 于 2020-11-19 设计创作，主要内容包括：本发明属于液体介电常数测量相关技术领域,其公开了一种液体相对介电常数的测量方法及系统,该方法包括：将待测液体滴加至介电材料层表面,获取此时所述待测液体的液滴与所述介电材料层的第一接触角；在所述介电材料层的背面设置至少覆盖所述液滴的金属层,将所述金属层和液滴分别与电源的正极和负极连接,以对所述液滴施加电压,稳定后获取此时所述液滴与所述介电材料层的第二接触角；根据上述第一接触角和第二接触角获取所述待测液体的相对介电常数。本申请中的方法和系统操作简单,普适性广,测量精度高。(The invention belongs to the technical field related to liquid dielectric constant measurement, and discloses a method and a system for measuring the relative dielectric constant of liquid, wherein the method comprises the following steps: dropwise adding liquid to be detected to the surface of the dielectric material layer to obtain a first contact angle between the liquid drop of the liquid to be detected and the dielectric material layer; arranging a metal layer at least covering the liquid drop on the back surface of the dielectric material layer, respectively connecting the metal layer and the liquid drop with a positive electrode and a negative electrode of a power supply to apply voltage to the liquid drop, and obtaining a second contact angle between the liquid drop and the dielectric material layer after stabilization; and acquiring the relative dielectric constant of the liquid to be measured according to the first contact angle and the second contact angle. The method and the system are simple to operate, wide in universality and high in measurement accuracy.)

1. A method of measuring the relative permittivity of a liquid, the method comprising:

s1, dripping the liquid to be detected on the surface of the dielectric material layer to obtain a first contact angle theta between the liquid drop of the liquid to be detected and the dielectric material layer₀；

S2, arranging a metal layer at least covering the liquid drop on the back surface of the dielectric material layer, respectively connecting the metal layer and the liquid drop with the negative electrode and the positive electrode of a power supply to apply voltage to the liquid drop, and obtaining a second contact angle theta between the liquid drop and the dielectric material layer after stabilization_e；

S3, substituting the first contact angle and the second contact angle into the following formula to obtain the relative dielectric constant epsilon of the liquid to be measured:

wherein d is the thickness of the dielectric material layer, σ is the surface tension of the liquid to be measured, ε₀For vacuum dielectric constant, U is the magnitude of the applied voltage.

2. The measurement method according to claim 1, characterized in that the first contact angle θ₀And a second contact angle theta_eThe calculation formula of (2) is as follows:

θ₀＝2arctan(2H₀/D₀)

θ_e＝2arctan(2H_e/D_e)

wherein H₀The height of the liquid drop to be measured carried on the dielectric material layer when no voltage is applied, D₀The contact width of the liquid drop to be detected carried on the dielectric material layer and the dielectric material layer when no voltage is applied; h_eFor the height, D, of the liquid drop to be measured carried on the layer of dielectric material after application of a voltage_eThe contact width of the liquid drop to be detected carried on the dielectric material layer and the dielectric material layer after voltage is applied is disclosed.

3. The measuring method according to claim 1, wherein step S2 further includes:

changing the applied voltage for multiple times, respectively obtaining corresponding second contact angles, and respectively calculating an average applied voltage and an average second contact angle which are obtained by averaging the applied voltage and the second contact angles for multiple times;

θ in step S3_eTo average second contact angle, U is the average applied voltage.

4. A system for implementing the method for measuring the relative dielectric constant of a liquid according to any one of claims 1 to 3, wherein the system comprises:

the supporting unit (100) sequentially comprises a metal layer (120) and a dielectric material layer (130) from bottom to top, and the liquid drop of the liquid to be detected is arranged on the dielectric material layer (130);

the voltage unit (200) comprises a power module (210), a positive terminal (220) connected with the positive electrode of the power module (210) and a negative terminal (230) with one end connected with the power module (210) and the other end connected with the metal layer (120), wherein the positive terminal (220) is in contact with the liquid to be measured;

a measurement unit (300) comprising an acquisition camera (310) and a data processor (320), wherein the acquisition camera (310) is configured to acquire images of the droplets after no voltage is applied and after a voltage is applied; the data processor (320) is used for acquiring the first contact angle and the second contact angle according to the image, and executing step S3 to acquire the relative dielectric constant of the liquid to be measured.

5. The system according to claim 4, wherein the support unit (100) further comprises an insulating layer (110) disposed under the metal layer (120) and a lifting structure (140) disposed under the insulating layer (110), wherein the lifting structure (140) is configured to adjust a height of the liquid droplet.

6. The system according to claim 4, wherein the power module (210) comprises an AC power source (211) and a power regulator (212), the AC power source (211) is connected to an input of the power regulator (212), and the power regulator (212) is configured to regulate the voltage of the AC power source (211) to a DC adjustable or AC adjustable voltage.

7. The system of claim 6, wherein the threshold U' of the output voltage of the power supply regulator (212) satisfies:

U′＜E_BDd

wherein E is_BDIs the critical breakdown electric field strength of the dielectric material layer (130), and d is the thickness of the dielectric material layer (130).

8. The system according to claim 4, characterized in that the voltage unit (200) comprises a three-dimensional displacement structure for fixing and adjusting the position of the positive terminal (220).

9. The system according to claim 4, wherein the measurement unit (300) further comprises a light source (330) for illuminating droplets of the liquid to be measured on the layer of dielectric material (130) for acquisition by the acquisition camera (310).

Technical Field

The invention belongs to the technical field related to liquid dielectric constant measurement, and particularly relates to a method and a system for measuring the relative dielectric constant of liquid.

Background

When a medium is placed in an electric field, molecules in the medium change such that the average electric field in the medium is smaller than the applied electric field, an effect known as the dielectric effect. The dielectric constant is an important basis for characterizing the electrical properties of dielectric or insulating materials, and represents the polarization characteristics of the medium, and different electronic devices can be prepared by utilizing the characteristics of the difference of the dielectric constants of different materials, so that the dielectric constant of the medium needs to be accurately measured in industrial application and scientific research.

In the prior art, a parallel plate capacitor structure is mostly adopted, and the dielectric constant of a medium is obtained by utilizing the relation between a vacuum capacitor and a dielectric capacitor, but the method is difficult to apply to a liquid medium. In the prior art, a refractive index sensor is adopted to measure the dielectric constant of the liquid, but the manufacturing cost is high, the process is complex, the operation is required frequently, and the measurement precision cannot be ensured, so that most of the conventional methods for measuring the dielectric constant of the liquid have the defects of unreasonable design, inaccurate result and the like.

Disclosure of Invention

Aiming at the defects or the improvement requirements of the prior art, the invention provides a method and a system for measuring the relative dielectric constant of liquid, wherein liquid drops of the liquid to be measured are arranged on a dielectric material layer, the polarization characteristics of the liquid drops are changed under the action of an electric field, so that the electric charges are concentrated in a three-phase line area, the liquid drops are spread due to mutual repulsion of like charges to influence the contact angle of the liquid drops, the relative dielectric constant of the liquid drops is obtained through calculation of the change of the contact angle of the liquid drops after the electric field is not applied and the electric field is applied, the device is simple, and the measurement is convenient and accurate.

To achieve the above object, according to one aspect of the present invention, there is provided a method for measuring a relative dielectric constant of a liquid, the method including: s1, dripping the liquid to be detected on the surface of the dielectric material layer to obtain a first contact angle theta between the liquid drop of the liquid to be detected and the dielectric material layer₀(ii) a S2, arranging a metal layer at least covering the liquid drop on the back of the dielectric material layer, and respectively connecting the metal layer and the liquid drop with the negative electrode and the positive electrode of a power supply to supply the liquidApplying a voltage to the liquid drop, and obtaining a second contact angle theta between the liquid drop and the dielectric material layer after the voltage is stabilized_e(ii) a S3, substituting the first contact angle and the second contact angle into the following formula to obtain the relative dielectric constant epsilon of the liquid to be measured:

wherein d is the thickness of the dielectric material layer, σ is the surface tension of the liquid to be measured, ε₀For vacuum dielectric constant, U is the magnitude of the applied voltage.

Preferably, the first contact angle θ₀And a second contact angle theta_eThe calculation formula of (2) is as follows:

θ₀＝2arctan(2H₀/D₀)

θe＝2arctan(2H_e/D_e)

wherein H₀The height of the liquid drop to be measured carried on the dielectric material layer when no voltage is applied, D₀The contact width of the liquid drop to be detected carried on the dielectric material layer and the dielectric material layer when no voltage is applied; h_eFor the height, D, of the liquid drop to be measured carried on the layer of dielectric material after application of a voltage_eThe contact width of the liquid drop to be detected carried on the dielectric material layer and the dielectric material layer after voltage is applied is disclosed.

Preferably, step S2 further includes:

changing the applied voltage for multiple times, respectively obtaining corresponding second contact angles, and respectively calculating an average applied voltage and an average second contact angle which are obtained by averaging the applied voltage and the second contact angles for multiple times;

θ in step S3_eTo average second contact angle, U is the average applied voltage.

According to another aspect of the present invention, there is provided a measuring system for implementing the above method for measuring a relative dielectric constant of a liquid, the system comprising: the supporting unit sequentially comprises a metal layer and a dielectric material layer from bottom to top, and the liquid drop of the liquid to be detected is arranged on the dielectric material layer; the voltage unit comprises a power module, a positive terminal connected with the positive electrode of the power module and a negative terminal connected with the metal layer, wherein one end of the negative terminal is connected with the power module, and the other end of the negative terminal is connected with the metal layer; the measuring unit comprises a collecting camera and a data processor, wherein the collecting camera is used for collecting images of the liquid drops after voltage is not applied and applied; the data processor is used for acquiring the first contact angle and the second contact angle according to the image, and executing step S3 to acquire the relative dielectric constant of the liquid to be measured.

Preferably, the supporting unit further includes an insulating layer disposed under the metal layer, and a lifting structure disposed under the insulating layer, wherein the lifting structure is configured to adjust a height of the liquid droplet.

Preferably, the power module includes an ac power source and a power regulator, the ac power source is connected to an input end of the power regulator, and the power regulator is configured to regulate a voltage of the ac power source to a dc adjustable voltage or an ac adjustable voltage.

Preferably, the threshold value U' of the output voltage of the power supply regulator satisfies:

U′＜E_BDd

wherein E is_BDD is the critical breakdown electric field strength of the dielectric material layer and d is the thickness of the dielectric material layer.

Preferably, the voltage unit includes a three-dimensional displacement structure for fixing and adjusting the position of the positive terminal.

Preferably, the measuring unit further comprises a light source for irradiating the liquid drop of the liquid to be measured on the dielectric material layer so as to be collected by the collecting camera.

Generally, compared with the prior art, the method and the system for measuring the relative dielectric constant of the liquid provided by the invention at least have the following beneficial effects:

1. the liquid drop has a contact angle on the surface of the dielectric material layer due to the action of surface tension, after voltage is applied to the liquid drop, charges in the liquid drop can be concentrated near a three-phase contact line, and the liquid drop is spread due to the repulsion action of charges with the same polarity, so that the appearance of the liquid drop is changed, the contact angle is reduced, the relative dielectric constant of the electric polarization characteristic of the reaction liquid drop can be calculated according to the change of the contact angle, the operation is simple, and the realization is easy;

2. the relative dielectric constant is calculated by applying different voltages for multiple times to obtain an average value, so that the calculation precision is greatly improved;

3. the equipment in the measuring system is simple and easy to obtain, and is convenient to operate, the voltage module can convert alternating current into direct current adjustable or alternating current adjustable voltage, the requirement for voltage transformation in the measuring process is met, due to the fact that different liquids have different polarization characteristics, the applied voltage needs to be increased when the liquid with the insignificant polarization characteristics is measured, and the applied voltage needs to be reduced when the liquid with the significant polarization characteristics is measured, and therefore the measuring system can meet the measuring requirements for relative dielectric constants of different liquids and is wide in universality;

4. the method and the device can realize the measurement of the relative dielectric constant of the liquid only by taking a small amount of liquid to be measured, greatly save raw materials and avoid waste.

Drawings

FIG. 1 schematically illustrates a schematic structural diagram of a liquid relative permittivity measurement system according to an embodiment of the present disclosure;

fig. 2 schematically shows a state diagram of a liquid to be measured after no voltage is applied and after voltage is applied according to an embodiment of the disclosure.

The same reference numbers will be used throughout the drawings to refer to the same or like elements or structures, wherein:

100-a support unit:

110-an insulating layer; 120-a metal layer; 130-a layer of dielectric material; 140-a lifting structure;

200-voltage unit:

210-a power supply module; 220-positive terminal; 230-negative pole connecting terminal; 211-ac power supply;

212-a power supply regulator; 240-switch;

300-measurement unit:

310-a capture camera; 320-a data processor; 330-a light source; 340-data lines;

400-liquid droplet to be tested.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

The invention provides a method for measuring relative dielectric constant of liquid, which comprises the following steps:

s1, dripping the liquid to be detected on the surface of the dielectric material layer to obtain a first contact angle theta between the liquid drop of the liquid to be detected and the dielectric material layer₀；

Wherein the first contact angle theta₀The calculation formula of (2) is as follows: theta₀＝2arctan(2H₀/D₀)。

Wherein H₀The height of the liquid drop to be measured carried on the dielectric material layer when no voltage is applied, D₀The contact width of the liquid drop to be measured carried on the dielectric material layer and the dielectric material layer when no voltage is applied is disclosed.

S2, arranging a metal layer at least covering the liquid drop on the back surface of the dielectric material layer, respectively connecting the metal layer and the liquid drop with the negative electrode and the positive electrode of a power supply to apply voltage to the liquid drop, and obtaining a second contact angle theta between the liquid drop and the dielectric material layer after stabilization_e；

Wherein the second contact angle theta_eThe calculation formula of (2) is as follows: theta_e＝2arctan(2H_e/D_e)。

H_eAfter applying a voltageHeight of liquid droplet to be measured carried on the dielectric material layer, D_eThe contact width of the liquid drop to be detected carried on the dielectric material layer and the dielectric material layer after voltage is applied is disclosed.

S3, substituting the first contact angle and the second contact angle into the following formula to obtain the relative dielectric constant epsilon of the liquid to be measured:

wherein d is the thickness of the dielectric material layer, σ is the surface tension of the liquid to be measured, ε is the vacuum dielectric constant, and U is the magnitude of the applied voltage.

The step S2 further includes changing the applied voltage for multiple times to obtain corresponding second contact angles, and averaging the applied voltage and the second contact angles for multiple times to obtain an average applied voltage and an average second contact angle; θ in step S3_eTo average second contact angle, U is the average applied voltage.

The present application also provides a measuring system for implementing the above-mentioned method for measuring the relative permittivity of a liquid, which includes a supporting unit 100, a voltage unit 200, and a measuring unit 300, as shown in fig. 1 and 2.

The supporting unit 100 sequentially includes a metal layer 120 and a dielectric material layer 130 from bottom to top, and the liquid drop 400 of the liquid to be measured is disposed on the dielectric material layer 130.

The supporting unit 100 further includes an insulating layer 110 disposed below the metal layer 120, and a lifting structure 140 disposed below the insulating layer 110, wherein the lifting structure 140 is configured to adjust a height of the droplet 400.

The voltage unit 200 comprises a power module 210, a positive terminal 220 connected to the positive electrode of the power module 210, and a negative terminal 230 connected to the metal layer 120 and connected to the other end of the power module 210, wherein the positive terminal 220 is in contact with the liquid to be tested and is used for applying voltage to the liquid 400 to be tested. The voltage unit 200 includes a three-dimensional displacement structure for fixing and adjusting the position of the positive connection terminal 220.

The power supply module 210 includes an ac power supply 211 and a power supply regulator 212, the ac power supply 211 is connected to an input end of the power supply regulator 212, and the power supply regulator 212 is configured to regulate a voltage of the ac power supply 211 to a dc adjustable voltage or an ac adjustable voltage. The threshold value U' of the output voltage of the power regulator 212 satisfies:

U'＜E_BDd

wherein E is_BDIs the critical breakdown electric field strength of the dielectric material layer 130, and d is the thickness of the dielectric material layer 130.

A measurement unit 300 comprising an acquisition camera 310 and a data processor 320, wherein the acquisition camera 310 is used for acquiring images of the droplets after no voltage is applied and after voltage is applied; the data processor 320 is configured to obtain the first contact angle and the second contact angle according to the image, and execute step S3 to obtain the relative dielectric constant of the liquid to be measured.

The measurement unit 300 further includes a light source 330 for illuminating the droplet 400 of the liquid to be measured on the dielectric material layer 130 to increase the brightness of the droplet for easy collection by the collection camera 310. The capture camera 310 is preferably a CCD camera.

The power module 210 further includes a switch 240, which is closed to start applying a voltage to the liquid drop, as shown in fig. 2, the charge in the liquid drop is concentrated near the three-phase contact line, a local electric field is distorted, Maxwell pressure in the electric field acts on the boundary, the equilibrium force is Laplace pressure, and meanwhile, the charge near the three-phase contact line is gathered, and the liquid drop is spread by the repulsion of like charges, so that the morphology of the liquid drop is changed, and the contact angle is reduced.

To sum up, on dielectric material layer was located to the liquid drop of the liquid that awaits measuring in this application, the liquid drop polarization characteristic changed under the effect of electric field for electric charge concentration and three-phase line region, because like charges repel each other makes the liquid drop to spread and then influence its contact angle, calculate the relative dielectric constant that obtains this liquid drop through the change of the contact angle after not applying the electric field and applying the electric field to this liquid drop, the device is simple, measures convenient accurate.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.