CN113640591A - Differential type micro electric field sensing device based on piezoelectric film deformation - Google Patents
Differential type micro electric field sensing device based on piezoelectric film deformation Download PDFInfo
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- CN113640591A CN113640591A CN202111043968.9A CN202111043968A CN113640591A CN 113640591 A CN113640591 A CN 113640591A CN 202111043968 A CN202111043968 A CN 202111043968A CN 113640591 A CN113640591 A CN 113640591A
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- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R29/00—Arrangements for measuring or indicating electric quantities not covered by groups G01R19/00 - G01R27/00
- G01R29/12—Measuring electrostatic fields or voltage-potential
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/26—Measuring inductance or capacitance; Measuring quality factor, e.g. by using the resonance method; Measuring loss factor; Measuring dielectric constants ; Measuring impedance or related variables
- G01R27/2605—Measuring capacitance
Abstract
A differential micro electric field sensing device based on piezoelectric film deformation comprises a piezoelectric film which is placed in the horizontal direction and can freely vibrate, electrodes are attached to two sides of the piezoelectric film, insulating layers are arranged on two sides of each electrode, a gap is reserved between each insulating layer and each electrode, a lower conducting layer is attached to one side, away from the piezoelectric film, of each insulating layer, insulating support structures are formed at two ends of two sides of each electrode respectively, and cavities are formed by the piezoelectric film, the electrodes, the insulating layers, the insulating support structures and the lower conducting layer; conductive columns are led out of the insulating support structures at the same ends of the two sides of the piezoelectric film and are connected with the electrodes; the two side structures of the piezoelectric film are symmetrically distributed by the piezoelectric film to form two capacitors, and the two capacitors form a parallel structure; the lower conducting layer and the conducting columns are respectively connected with external capacitance measuring equipment and used for measuring capacitance. The device has the advantages of small volume, low manufacturing cost, good linearity and high sensitivity, and can meet the electric field measurement requirements of power grids and equipment.
Description
Technical Field
The invention relates to the field of electric field measurement, in particular to a differential micro electric field sensing device based on piezoelectric film deformation.
Background
The core of the ubiquitous power Internet of things is to construct an information network matched with an energy network and realize management and control of the energy network on an information level. The intelligent and strong construction of the energy network can be realized by constructing the ubiquitous power internet of things, and the stability and the economical efficiency of the energy network are improved. The sensors are key components for constructing an information network, and people can realize real-time perception of different physical quantities through sensing nodes formed by various sensors, so that dynamic monitoring of network and equipment information is realized.
Among the physical quantities, the electric field is an important physical quantity in the power network. On one hand, the electric field measurement can be used for the applications of power grid electromagnetic environment monitoring, near-electricity warning, lightning early warning and the like, and meanwhile, the electric field measurement also has wide application in the fields of space launching, petrochemical industry and the like. On the other hand, voltage inversion by electric field measurement can realize non-invasive measurement of voltage. The fingerprint information of the voltage signal contains a large amount of information, can reflect the running state of the power grid, simultaneously realizes fault prediction and fault diagnosis, and has important significance for the safety of the power grid.
The traditional electric field measurement equipment, such as a field mill, has large volume and low precision, and cannot realize high-performance electric field measurement. The micro electric field sensor is a sensor prepared based on a micro-processing technology, and the sensor is low in cost, high in resolution, small in size, suitable for batch production and wide-area arrangement and capable of realizing wide-area monitoring of information. At present, the more mature electric field sensors are based on the electro-optic effect, and the sensors measure the electric field through the change of the refractive index of the electro-optic crystal under the electric field. Such electric field sensors have high frequency response and high accuracy and are currently used in a variety of applications. However, such sensors have low temperature stability and high cost of light emitting and receiving devices, and cannot be arranged in a wide range. Another type of sensor is a MEMS sensor, which uses the principle of electrostatic induction to measure an electric field. However, such sensors have large power consumption and low cut-off frequency, and cannot be used in many application scenarios. The piezoelectric material can generate deformation when an electric field is applied, and meanwhile, the response frequency response is high, the dynamic range is large, and electric field measurement can be realized. By utilizing the piezoelectric material, the electric field measuring equipment with low cost and high performance can be designed and used for measuring the voltage and the electric field in the ubiquitous power Internet of things.
Disclosure of Invention
In order to solve the problems, the invention provides a differential micro electric field sensing device based on piezoelectric film deformation, which achieves the purpose of measuring an electric field by measuring capacitance.
In order to achieve the above purpose, the present invention provides a differential micro electric field sensing device based on piezoelectric film deformation, which includes a piezoelectric film capable of freely vibrating and placed along a horizontal direction, electrodes are attached to two sides of the piezoelectric film, insulating layers are disposed on two sides of the electrodes, a gap is left between the insulating layer and the electrodes, a lower conductive layer is attached to one side of the insulating layer away from the piezoelectric film, insulating support structures are respectively formed at two ends of two sides of the electrodes, and a cavity is formed by the piezoelectric film, the electrodes, the insulating layers, the insulating support structures and the lower conductive layer; conductive columns are led out of the insulating support structures at the same ends of the two sides of the piezoelectric film and are connected with the electrodes; the two side structures of the piezoelectric film are symmetrically distributed on the piezoelectric film to form two capacitors, and the two capacitors form a parallel structure; and the lower conducting layer and the conducting column are respectively connected with external capacitance measuring equipment and used for measuring the capacitance.
Preferably, the piezoelectric film is made of a piezoelectric material with a small dielectric constant and large piezoelectric coefficients d31 and d 32.
Preferably, the piezoelectric film is composed of two piezoelectric films with opposite polarization directions.
Preferably, the piezoelectric film is 1 micron to 30 microns thick and 100 microns to millimeter in size.
Preferably, the electrodes are of a metallic material.
Preferably, the lower conductive layer is made of a highly doped low-resistivity silicon material.
Preferably, the insulating layer is silicon oxide.
Preferably, the cavity is in the form of a sealing structure.
Preferably, the cavity is filled with an insulating medium.
Preferably, the void height is taken to be 1um-20 um.
The invention has the beneficial effects that: the response of the piezoelectric film under the electric field is utilized to measure the electric field, the periphery of the film is fixed, the transverse deformation of the film is converted into the longitudinal vibration of the film, the amplification of the response of the film is realized, and the sensitivity of the sensor is improved. Meanwhile, the piezoelectric material has the advantages of high breakdown field intensity, high frequency response and the like, and is suitable for broadband high-electric-field measurement. Meanwhile, the piezoelectric material has high temperature stability, and the sensor can be slightly influenced by the environment. The capacitance structure is used for measuring an electric field, and the deformation of the piezoelectric film is converted into the change of the distance between the upper electrode and the lower electrode of the capacitor, so that the change of the capacitance value is converted. The two capacitors are connected in parallel, and the piezoelectric film is used as a common electrode of the two capacitors to form a differential structure, so that high linearity of capacitance change is realized. The design of the conductive column structure ensures the absolute pressure characteristic of the capacitor cavity, and the upper electrode of the capacitor does not need to be led out through opening the cavity. This facilitates the provision of different media, such as gas, insulating oil, etc., in the cavity.
Drawings
FIG. 1 is a cross-sectional view of the structure of the differential micro electric field sensing device based on the deformation of the piezoelectric film according to the present invention.
In the figure, 1, a piezoelectric film; 2. an electrode; 3. a cavity; 4. an insulating layer; 5. an insulating support structure; 6. a lower conductive layer; 7. a conductive post; 8. a capacitance measuring device.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings.
Piezoelectric materials deform under the action of an electric field, and the effect is called inverse piezoelectric effect.
Under the action of an electric field perpendicular to the film, the piezoelectric film generates horizontal deformation due to inverse piezoelectric effect, and the piezoelectric film consisting of two piezoelectric films with opposite polarization directions vibrates up and down due to the fact that the deformation directions of the two piezoelectric films are opposite and the periphery of the piezoelectric film is fixed. The film is used as an upper electrode of the capacitor, the other fixed electrode is used as a lower electrode of the capacitor, and when the film vibrates up and down, the distance between the capacitor electrodes changes, so that the capacitance changes. The electric field measurement can be achieved by measuring the change in capacitance.
When the displacement of the piezoelectric film is d, the capacitance value C of a single capacitor is
Wherein epsilon is dielectric permittivity and S is capacitance electrode area. The capacitance change is:
the two capacitors are symmetrically arranged, and the piezoelectric film is used as a common electrode of the two capacitors, so that high-linearity electric field measurement can be realized.
When two capacitors are provided, the two capacitors are respectively C1 and C2, when Δ d/d < 1:
when two capacitors are connected in parallel, the capacitance change value is the addition of the two capacitors, the odd terms are cancelled, and the output linearity is increased.
According to the design thought, the invention provides a differential micro electric field sensing device based on piezoelectric film deformation, which comprises a piezoelectric film 1 which is arranged along the horizontal direction and can freely vibrate, wherein the piezoelectric film 1 consists of two piezoelectric films with opposite polarization directions, electrodes 2 are attached to two sides of the piezoelectric film 1, insulating layers 4 are arranged on two sides of each electrode 2, a gap is reserved between each insulating layer 4 and each electrode, the height of the gap is generally 1-20 um, a lower conducting layer 6 is attached to one side, far away from the piezoelectric film, of each insulating layer 4, insulating support structures 5 are respectively formed at two ends of two sides of each electrode 2, and a cavity 3 is formed by the piezoelectric film 1, the electrodes 2, the insulating layers 4, the insulating support structures 5 and the lower conducting layer 6. The support structure 5 is connected with the lower conducting layer and the insulating layer through glass pouring and micromachining processes. And a conductive column 7 is led out from the insulating support structure 5 at the same end of the two sides of the piezoelectric film 1, and the conductive column 7 is connected with the electrode 2. The two side structures of the piezoelectric film 1 are symmetrically distributed on the piezoelectric film 1 to form two capacitors, and the two capacitors form a parallel structure. The lower conductive layer 6 and the conductive column 7 are respectively connected to an external capacitance measuring device 8 for measuring capacitance. Two symmetrical capacitor structures are arranged on two sides of the piezoelectric film 1, when the piezoelectric film 1 vibrates, the distance between two capacitor plates is increased and decreased one by one, the two capacitors are connected into a parallel structure, and high linearity measurement of an electric field can be realized.
The shape of the piezoelectric film 1 may be circular or square. The piezoelectric film 1 is made of a material with larger piezoelectric coefficients d31 and d32, which can be larger in deformation under an electric field, and a material with a smaller dielectric constant is selected, so that a larger electric field can be induced inside the material under the same external electric field. The material of the piezoelectric film 1 is preferably an organic piezoelectric material such as PVDF or the like. The thickness of the film is 1 micrometer to 30 micrometers, and the length and width of the film are 100 micrometers to millimeter.
The electrode 2 is made of conductive material, such as metal, and is used as the upper electrode of the capacitor, and the thickness is generally 100nm-1 um.
The insulating support structure is made of insulating materials, and glass is generally used as the material in order to adapt to the micro-machining process. The insulating support structure is used for fixing the periphery of the piezoelectric film, and meanwhile, a cavity is formed in the middle of the insulating support structure to guarantee free vibration of the piezoelectric film.
The lower conductive layer 6 is used as a lower electrode of the capacitor, and can adopt high-doped low-resistivity silicon as a material, and the thickness is generally 100-300 um.
The insulating layer 4 is disposed on the surface of the lower conductive layer 6, and is used to prevent the electrode 2 from being conducted with the lower conductive layer 1 when the piezoelectric film 1 is deformed too much. The insulating layer 4 can be made of silicon oxide, and is prepared by growing silicon oxide on silicon, and the thickness is generally 20nm-100 nm.
The cavity adopts a sealing structure as a capacitor medium, and different types of insulating media such as air, insulating oil and the like can be filled in the cavity according to requirements.
And the conductive column 7 is arranged in the insulating support structure and is connected with the electrode 2, so that the sealed leading-out of the upper electrode of the capacitor is realized.
The technical solutions described above only represent the preferred technical solutions of the present invention, and some possible modifications to some parts of the technical solutions by those skilled in the art all represent the principles of the present invention, and fall within the protection scope of the present invention.
Claims (10)
1. A differential micro electric field sensing device based on piezoelectric film deformation comprises a piezoelectric film which is placed in the horizontal direction and can freely vibrate, electrodes are attached to two sides of the piezoelectric film, insulating layers are arranged on two sides of each electrode, a gap is reserved between each insulating layer and each electrode, a lower conducting layer is attached to one side, away from the piezoelectric film, of each insulating layer, insulating supporting structures are formed at two ends of two sides of each electrode respectively, and a cavity is formed by the piezoelectric film, the electrodes, the insulating layers, the insulating supporting structures and the lower conducting layer; conductive columns are led out of the insulating support structures at the same ends of the two sides of the piezoelectric film and are connected with the electrodes; the two side structures of the piezoelectric film are symmetrically distributed on the piezoelectric film to form two capacitors, and the two capacitors form a parallel structure; and the lower conducting layer and the conducting column are respectively connected with external capacitance measuring equipment and used for measuring the capacitance.
2. The differential miniature electric field sensing device of claim 1, wherein said piezoelectric film is made of a piezoelectric material with a low dielectric constant and high piezoelectric coefficients d31 and d 32.
3. The differential miniature electric field sensing device according to claim 1, wherein said piezoelectric film comprises two piezoelectric films with opposite polarization directions.
4. The differential miniature electric field sensing device based on deformation of piezoelectric film as claimed in claim 1, wherein said piezoelectric film has a thickness of 1 μm to 30 μm and a length and width dimension of 100 μm to mm.
5. The differential miniature electric field sensing device based on deformation of a piezoelectric film as claimed in claim 1, wherein said electrode is made of a metallic material.
6. The differential miniature electric field sensing device based on deformation of piezoelectric film as claimed in claim 1, wherein said lower conductive layer is made of highly doped low resistivity silicon material.
7. The differential miniature electric field sensing device based on deformation of a piezoelectric film according to claim 1, wherein said insulating layer is silicon oxide.
8. The differential miniature electric field sensing device based on deformation of piezoelectric film as claimed in claim 1, wherein said cavity is a sealed structure.
9. The differential miniature electric field sensing device based on deformation of piezoelectric film as claimed in claim 1 or 7, wherein said cavity is filled with an insulating medium.
10. The differential miniature electric field sensing device based on deformation of piezoelectric film as claimed in claim 1, wherein said gap height is in the range of 1um-20 um.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114200239A (en) * | 2021-12-10 | 2022-03-18 | 清华大学 | Method for online monitoring failure of insulator monomer in insulator string in power system |
| CN114545103A (en) * | 2022-01-14 | 2022-05-27 | 深圳市中明科技股份有限公司 | Wireless transmission electrostatic field detection device and wireless power supply system |
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Cited By (2)
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| CN114545103A (en) * | 2022-01-14 | 2022-05-27 | 深圳市中明科技股份有限公司 | Wireless transmission electrostatic field detection device and wireless power supply system |
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