Electric field sensitive element, preparation method and non-invasive electric field sensor

Abstract

The invention discloses an electric field sensitive element, a preparation method and a non-invasive electric field sensor, the electric field sensitive element comprises a piezoelectric material layer and a metal material layer, the metal material layer is arranged on the piezoelectric material layer, the metal material layer is of a Wheatstone bridge structure on the piezoelectric material layer to form the electric field sensitive element, and an electric field is applied outside the electric field sensitive element. The piezoelectric-piezoresistive electric field sensor is simple in technological process, high in yield and capable of being produced in batches. Compared with a semiconductor piezoresistive material, the metal strain material is relatively small in temperature coefficient, relatively low in sensitivity to temperature change and relatively good in stability. In addition, the metal strain material has strong adaptability to the environment and is suitable for various complex power grid application scenes.

Description

Technical Field

[0001] The present invention belongs to the technical field of sensors, and particularly relates to an electric field sensitive element, a preparation method, and a non-invasive electric field sensor. Background Art

[0002] With the rapid development of smart grids, higher requirements are put forward for electric field sensing technology, especially in the fields of real-time voltage monitoring, wide-area distributed information collection, and non-invasive electric field measurement. Electrical signals in the power grid have broadband characteristics in both the frequency domain and the time domain. In addition to traditional AC and DC steady-state signals, they also include harmonics, transient stability signals, power frequency slow transients, operation fast transients, lightning fast transients, and very fast transients. The voltage range is from V to MV magnitude, and the frequency is from DC to hundreds of MHz. In the actual monitoring process, the sensor often has to face complex geographical, climatic, and electromagnetic environments. The changes in terrain, weather, and the insulation requirements of equipment under high field strength all pose extremely high requirements for the performance of the sensor. In addition, non-contact measurement is generally carried out in the power grid monitoring scenario because contact measurement may affect the power quality of the system itself, and at the same time, it will also pose high requirements for equipment insulation. And when monitoring, it is necessary to ensure that the interference of the sensor to the original electric field is minimized as much as possible.

[0003] Currently, the most commonly used monitoring devices in the power grid are voltage and current transformers based on the principle of coil winding transformation. However, the existing voltage and current transformers have great limitations. For example, the sensor has a large volume and is difficult to install on transmission and distribution lines with limited space; the manufacturing cost is high, consuming a large amount of metal resources and cannot be used economically on a large scale; the sensor has a single function and is only applicable to power frequency AC signals, and cannot measure DC, transient, and higher harmonic signals. In addition, although MEMS electric field sensors based on the piezoelectric-piezoresistive mechanism have been developed, there are still problems such as high cost, complex preparation process, and inability to mass-produce. Summary of the Invention

[0004] The purpose of the present invention is to provide an electric field sensitive element, a preparation method, and a non-invasive electric field sensor to solve the above problems.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions: An electric field sensitive element includes: a piezoelectric material layer and a metal material layer. The metal material layer is disposed on the piezoelectric material layer, and the metal material layer forms a Wheatstone bridge structure on the piezoelectric material layer to form an electric field sensitive element, and an electric field is applied outside the electric field sensitive element.

[0006] Further, the piezoelectric material layer is a piezoelectric single crystal or a piezoelectric ceramic.

[0007] Further, the metal material layer is a Kanthal alloy or a nickel-chromium alloy.

[0008] A preparation method of an electric field sensitive element, comprising: Pre-treating a piezoelectric substrate; Performing development of a preset shape on the pre-treated piezoelectric substrate; Depositing a metal piezoresistive film on the developed piezoelectric substrate to obtain an electric field sensitive element.

[0009] Further, the pre-treatment includes: cleaning the piezoelectric substrate with acetone, ethanol and deionized water.

[0010] Further, exposing a preset mask plate through a lithography machine, and developing the exposed piezoelectric substrate with a developer.

[0011] Further, depositing a metal piezoresistive film using a magnetron sputtering device, and removing the excess metal film with a stripping solution to obtain an electric field sensitive element.

[0012] A non-invasive electric field sensor, comprising the electric field sensitive element, a low-noise signal conditioning and amplifying circuit, a microprocessing unit and a power supply module; the electric field sensitive element is connected to the low-noise signal conditioning and amplifying circuit, the low-noise signal conditioning and amplifying circuit is connected to the microprocessing unit, and the power supply module is used to supply power to the electric field sensitive element, the low-noise signal conditioning and amplifying circuit and the microprocessing unit; the low-noise signal conditioning and amplifying circuit filters and differentially amplifies the output voltage of the electric field sensitive element; the microprocessing unit is used for data acquisition and data transmission.

[0013] Further, the microprocessing unit includes a data acquisition circuit and a wireless transmission module, the data acquisition circuit is used to sample the output of the low-noise signal conditioning and amplifying circuit, and the sampled data is sent to an external data monitoring center through the wireless transmission module.

[0014] Further, the low-noise signal conditioning and amplifying circuit, the microprocessing unit and the power supply module are arranged inside a shielding housing.

[0015] Compared with the prior art, the present invention has the following technical effects: The piezoelectric-piezoresistive electric field sensor mentioned in the present invention has a simple technological process, a high yield rate, and can be mass-produced. Compared with semiconductor piezoresistive materials, the temperature coefficient of metal strain materials is relatively small, the sensitivity to temperature changes is relatively low, and the stability is good. In addition, the metal strain materials have strong environmental adaptability and are suitable for various complex power grid application scenarios.

[0016] The piezoresistive material of the present invention is directly deposited on the surface of the piezoelectric material. This direct coupling method does not require an adhesive in the middle. The adhesive will introduce strain transfer errors, and the adhesive is prone to aging, which is not conducive to the stability and durability of the sensor. Description of the Drawings

[0017] Figure 1 Schematic diagram of the working of the electric field sensitive element in a spatial electric field; Figure 2 Schematic diagram of a Wheatstone bridge (full bridge); Figure 3 Process preparation flow of the electric field sensitive element; Figure 4 System block diagram of the electric field sensor based on the field-induced resistance change effect; Figure 5 Output diagram of the electric field sensor in different electric field environments. Specific implementation mode

[0018] The present invention is further described below in conjunction with the accompanying drawings: Embodiment 1, an electric field sensitive element, comprising: a piezoelectric material layer and a metal material layer, the metal material layer is disposed on the piezoelectric material layer, and the metal material layer forms a Wheatstone bridge structure on the piezoelectric material layer to form an electric field sensitive element, and an electric field is applied outside the electric field sensitive element.

[0019] The direct coupling of the inverse piezoelectric effect of the piezoelectric material and the piezoresistive effect of the metal material is used for spatial electric field monitoring. The piezoelectric materials mentioned here include but are not limited to piezoelectric single crystals, piezoelectric ceramics and other piezoelectric materials. The metal materials mentioned here include but are not limited to metals, alloys and other materials. As Figure 1 shown, in this patent, a patterned metal thin film is directly deposited on a piezoelectric substrate. Due to the inverse piezoelectric effect, the piezoelectric material in the spatial electric field will undergo tensile or compressive strain. The metal thin film deposited on the piezoelectric substrate will deform with the strain of the piezoelectric material. Due to the metal resistance strain effect, the resistance of the metal thin film will change. Therefore, the change of the spatial electric field can be deduced from the change of the resistance of the metal thin film.

[0020] Since the strain of the piezoelectric material in the electric field is in-plane isotropic or anisotropic, this effect can be used to introduce a Wheatstone bridge full bridge design. The Wheatstone bridge can, on the one hand, improve the sensitivity of the electric field sensitive element, and on the other hand, reduce the influence of temperature on the measurement result. The design of the Wheatstone bridge is as Figure 2 shown, the metal resistances R1 and R3 increase (decrease) in resistance after being subjected to tensile (compressive) action, and the metal resistances R2 and R4 decrease (increase) in resistance after being subjected to compressive (tensile) action. That is, when ΔR1 = -ΔR2 = ΔR3 = -ΔR4, a Wheatstone differential full bridge is formed, and the output voltage can be maximized and the bridge sensitivity can be maximized.

[0021] The piezoelectric material generates mechanical strain under the action of the electric field, driving the metal thin film to deform, and its resistance changes significantly, which can accurately reflect the change of the spatial electric field.

[0022] The Wheatstone bridge design effectively reduces the impact of environmental factors such as temperature on the measurement results and improves the stability and reliability of the measurement.

[0023] Piezoelectric materials have in-plane anisotropy in an electric field. Through the Wheatstone bridge full-bridge design, this characteristic can be fully utilized to maximize the output voltage and bridge sensitivity.

[0024] Embodiment 2, a method for preparing an electric field sensitive element, comprising: Piezoelectric substrate pretreatment; Performing preset shape development on the pre-treated piezoelectric substrate; A metal piezoresistive film is deposited on the developed piezoelectric substrate to obtain an electric field sensitive element.

[0025] Preparation process Figure 3 As shown, it is mainly divided into the following four steps. The first step: use acetone, ethanol and deionized water to clean the piezoelectric substrate; the second step: use the pre-designed mask to expose it through the photolithography machine, and then use the developer to develop the exposed piezoelectric substrate; the third step: use the magnetron sputtering equipment to deposit the metal piezoresistive film; the fourth step: use the degumming liquid (such as acetone) to remove the excess metal film. At this point, the electric field sensitive element is prepared.

[0026] By using a photolithography machine for exposure and development, the pattern of the metal film can be precisely controlled, which simplifies the traditional process and improves production efficiency.

[0027] The use of magnetron sputtering equipment to deposit metal piezoresistive films ensures the uniformity and adhesion of the films, and improves the reliability and stability of the components.

[0028] The entire preparation process does not require complicated equipment, has low cost, and has good repeatability, making it easy for large-scale production.

[0029] Embodiment 3, a non-invasive electric field sensor, includes the electric field sensitive element, low-noise signal conditioning and amplifying circuit, microprocessing unit and power module; the electric field sensitive element is connected to the low-noise signal conditioning and amplifying circuit, the low-noise signal conditioning and amplifying circuit is connected to the microprocessing unit, the power module is used to supply power to the electric field sensitive element, the low-noise signal conditioning and amplifying circuit and the microprocessing unit; the low-noise signal conditioning and amplifying circuit filters and differentially amplifies the output voltage of the electric field sensitive element; the microprocessing unit is used for data acquisition and data transmission.

[0030] The microprocessing unit includes a data acquisition circuit and a wireless transmission module. The data acquisition circuit is used to sample the output of the differential amplification module, and the sampled data is sent to the data monitoring center through the wireless transmission module. The power supply module is responsible for providing a stable operating voltage to the electric field sensitive element, the low-noise signal conditioning and amplification circuit, and the microprocessing unit. The shielding enclosure is made of metal to isolate the sensor from the external electric field and eliminate the interference of the external electric field on the non-contact voltage sensor.

[0031] The electric field sensor prepared by the above method is placed in the space electric field environment built by parallel metal plates for testing, and the test results are as Figure 5 shown. As the external electric field changes, the output voltage of the electric field sensor shows a linear trend. This proves that the non-contact electric field sensor prepared in this paper not only has the advantages of small volume and low cost, but also has great advantages in sensing performance.

[0032] The sensor is small in size and low in cost, but excellent in sensing performance. The test results show that its output voltage has a good linear relationship with the change of the external electric field.

[0033] The shielding enclosure effectively isolates the interference of the external electric field and ensures the accuracy and reliability of the sensor.

[0034] The low-noise signal conditioning and amplification circuit filters and differentially amplifies the output signal, improving the signal-to-noise ratio of the signal; the microprocessing unit realizes the real-time acquisition and transmission of data, facilitating remote monitoring and analysis.

[0035] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: still can modify the specific implementation manners of the present invention or make equivalent replacements, and any modification or equivalent replacement that does not depart from the spirit and scope of the present invention shall be covered by the protection scope of the claims of the present invention.

Claims

1. An electric field sensitive element, characterized in that: include: A piezoelectric material layer and a metal material layer, wherein the metal material layer is arranged on the piezoelectric material layer, and the metal material layer presents a Wheatstone bridge structure on the piezoelectric material layer to form an electric field sensitive element, and an electric field is applied outside the electric field sensitive element.

2. An electric field sensor according to claim 1, characterized in that: The piezoelectric material layer is a piezoelectric single crystal or a piezoelectric ceramic.

3. The electric field sensor according to claim 1, characterized in that: The metal material layer is kama alloy or nickel-chromium alloy.

4. A method for preparing an electric field sensitive element according to any one of claims 1 to 3, characterized in that: include: Piezoelectric substrate pretreatment; Performing preset shape development on the pre-treated piezoelectric substrate; A metal piezoresistive film is deposited on the developed piezoelectric substrate to obtain an electric field sensitive element.

5. The method for preparing an electric field sensitive element according to claim 4, characterized in that: Preprocessing includes: The piezoelectric substrate was cleaned with acetone, ethanol, and deionized water.

6. The method for preparing an electric field sensitive element according to claim 4, characterized in that: The preset mask is exposed by a photolithography machine, and the exposed piezoelectric substrate is developed using a developer.

7. The method for preparing an electric field sensitive element according to claim 4, characterized in that: A metal piezoresistive film is deposited using a magnetron sputtering device, and excess metal film is removed using a degumming solution to obtain an electric field sensitive element.

8. A non-invasive electric field sensor, characterized in that: It comprises an electric field sensitive element, a low-noise signal conditioning amplifier circuit, a microprocessing unit and a power supply module as described in any one of claims 1 to 4; the electric field sensitive element is connected to the low-noise signal conditioning amplifier circuit, the low-noise signal conditioning amplifier circuit is connected to the microprocessing unit, and the power supply module is used to supply power to the electric field sensitive element, the low-noise signal conditioning amplifier circuit and the microprocessing unit; the low-noise signal conditioning amplifier circuit filters and performs differential amplification processing on the output voltage of the electric field sensitive element; the microprocessing unit is used for data acquisition and data transmission.

9. The non-invasive electric field sensor according to claim 8, characterized in that: The microprocessing unit includes a data acquisition circuit and a wireless transmission module. The data acquisition circuit is used to sample the output of the low-noise signal conditioning and amplification circuit, and the sampled data is sent to an external data monitoring center through the wireless transmission module.

10. The non-invasive electric field sensor according to claim 8, characterized in that: The low-noise signal conditioning and amplifying circuit, the microprocessing unit and the power supply module are arranged inside the shielding shell.

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