A resonant MEMS electric field sensor based on the A0 mode of Lamb waves

Abstract

The present application relates to the technical field of micro electro mechanical system and the technical field of electric field detection, and particularly relates to a resonant MEMS electric field sensor based on a Lamb wave A0 mode, which comprises a substrate, an electric field sensitive resonator main body, an input metal transmission line, an output metal transmission line, an input metal electrode disc and an output metal electrode disc; the electric field sensitive resonator main body is suspended on the substrate, and is connected to the substrate through a pair of long strip-shaped anchor points, so as to reduce the mechanical constraint of the substrate on the free vibration of the electric field sensitive resonator and reduce the leakage of acoustic energy. In the electric field sensitive resonator main body, the performance is improved through multiple structure design. The area ratio of the interdigital electrode to the piezoelectric film is controlled to be 25%, and the interdigital electrode is arranged at a position with concentrated strain, and is matched with the piezoelectric film with a periodic groove structure and the piston electrode structure with a widened end, so that the A0 mode can be effectively excited, and the contact area of the piezoelectric film and the measured electric field is increased. The present application improves the electric field sensitivity and the anti-interference ability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of Micro-Electro-Mechanical Systems (MEMS) and the technical field of electric field detection, and particularly relates to a resonant MEMS electric field sensor based on a Lamb wave A0 mode. BACKGROUND

[0002] With the rapid development of Internet of Things (IoT), smart grid and Industry 4.0, the demand for high-precision electric field sensors is increasing. Such sensors play a key role in power system detection (such as partial discharge detection), aerospace, industrial safety, biomedical, electric field imaging, and environmental electromagnetic field evaluation. Electrostatic discharge and lightning effect are one of the main causes of major safety accidents such as oil and gas storage and transportation fires and failure of military electronic equipment. Traditional electric field measurement devices generally use exposed movable mechanical structures, which are prone to friction electrification due to mechanical impact, thereby causing discharge risk, which seriously restricts their reliability in hazardous working conditions such as dust-rich or oil and gas environments.

[0003] With the development of MEMS micro-nano processing technology, resonant MEMS sensors based on piezoelectric materials have attracted widespread attention due to their low power consumption, small size, no exposed movable structure, and easy integration. MEMS micro-nano processing technology is a cross-scale manufacturing method based on semiconductor manufacturing processes, which can accurately construct micron to nanometer functional structures and realize heterogeneous integration, thereby manufacturing integrated and miniaturized sensor devices.

[0004] According to the different working principles, MEMS electric field sensors are mainly divided into three types: charge type, capacitance type and resonant type. Among them, the charge type MEMS electric field sensor periodically shields or exposes the sensing electrode, and uses the flow of induced charge to output induced current, but its sensitivity is low and it is easily disturbed by environmental temperature and parasitic capacitance. The capacitance type MEMS electric field sensor uses the deformation of the capacitance structure caused by the external electric field to indirectly measure the electric field strength by measuring the capacitance value, but its structure is complex and requires an additional direct current driving signal, which increases the power consumption. In contrast, the resonant MEMS electric field sensor is based on the frequency modulation effect of the resonator. When an external electric field is applied to the surface of the piezoelectric material, due to the inverse piezoelectric effect, a strain will be generated in the piezoelectric film, which will change the effective stiffness of the material and cause the natural frequency to shift. By detecting the frequency change, the resonant MEMS sensor can convert the external electric field signal into an easily detected electrical signal, and has the advantages of no need for direct current bias, strong noise resistance, simple structure, etc. However, due to material and structural limitations, its sensitivity and spatial longitudinal direction direct current electric field measurement accuracy still need to be improved. SUMMARY

[0005] The present application aims at the problems of complex structure, weak anti-noise ability and low sensitivity of the electric field sensor in the prior art, and provides a piezoelectric resonant electric field sensor based on a Lamb wave A0 mode.

[0006] To achieve the above object, the present application adopts the following technical scheme:

[0007] A piezoelectric resonant electric field sensor based on a Lamb wave A0 mode comprises a substrate, an electric field sensitive resonator main body, an input metal transmission line, an output metal transmission line, an input metal electrode disc and an output metal electrode disc.

[0008] The substrate is composed of two single crystal silicon layers closely adhered together, and a full-coverage second isolation oxide layer is embedded between the two single crystal silicon layers to form a sandwiched laminated structure, and a through hole penetrating through the two single crystal silicon layers and the second isolation oxide layer is arranged in the structure to form a hollow area.

[0009] The electric field sensitive resonator main body is arranged in a suspended manner in the hollow area and connected to the substrate through an anchor at each end thereof; and the electric field sensitive resonator main body is composed of an input interdigital electrode, an output interdigital electrode, a piezoelectric thin film and a heavily doped single crystal silicon layer arranged in sequence from top to bottom.

[0010] One end of the input metal transmission line is connected to the input interdigital electrode, and the other end is connected to the input metal electrode disc; one end of the output metal transmission line is connected to the output interdigital electrode, and the other end is connected to the output metal electrode disc.

[0011] The input metal electrode disc and the output metal electrode disc are arranged on the upper surface of the substrate, and a grounding metal disc is arranged on each side of the input metal electrode disc, and a grounding metal disc is also arranged on each side of the output metal electrode disc.

[0012] Further, the input metal transmission line and the output metal transmission line are each composed of a transmission segment and a transition segment; the transmission segment is arranged on the upper surface of the substrate layer, one end of the transmission segment is connected to one end of the transition segment, and the other end of the transmission segment is connected to the metal electrode disc; the transition segment is arranged on the upper surface of the piezoelectric thin film, and the other end of the transition segment is connected to the interdigital electrode.

[0013] Further, a first isolation oxide layer electrically isolated from the substrate is arranged below all the metal electrode discs and the transmission segments of the metal transmission lines.

[0014] Further, the material of the first and second isolation oxide layers is silicon dioxide, and the thickness is 0.3-1.5 μm.

[0015] Further, the input and output interdigital electrodes are arranged in a symmetrical and alternating manner on the piezoelectric film and have the same polygonal metal sheet, and the overall size is smaller than that of the piezoelectric film, and the width of the electrode strips at the ends of the input and output interdigital electrodes is widened to form a piston structure.

[0016] Further, the input and output interdigital electrodes are located at the central strain concentration position of the piezoelectric film, and can more effectively excite the A0 mode of the electric field sensitive resonator.

[0017] Further, the piezoelectric film under the gap between the input and output interdigital electrodes is selectively etched to form a periodic groove structure on the side of the piezoelectric film in contact with the interdigital electrodes.

[0018] Further, the total area of the input and output interdigital electrodes is 25% of the total area of the piezoelectric film, which can ensure normal excitation of the A0 mode and has a larger contact area between the piezoelectric film and the measured electric field, thereby improving the sensitivity of the electric field measurement.

[0019] Further, the piezoelectric film is a rectangular piezoelectric material film deposited by a vacuum sputtering method. Further, the metal transmission line, the metal electrode disc and the interdigital electrode are made of gold, silver, copper, aluminum, nickel or platinum, and the thickness is 0.2-2 μm; the piezoelectric film is made of LiNbO3, PZT, AlN, ZnO, PVDF, LiTaO3 and other piezoelectric materials, and the thickness is 0.1-1 μm.

[0020] Further, the anchor points are long strip structures at the connection between the resonator body and the substrate, and the electric field sensitive resonator body is fixed to the hollow area of the substrate through the anchor points.

[0021] After the above technical scheme is adopted, the present application has the following beneficial effects:

[0022] 1. The piezoelectric resonant electric field sensor in the present application excites the normal operation and signal output of the electric field sensitive resonator through the positive / negative piezoelectric effect of the piezoelectric film material, realizes the mutual conversion between electric energy and mechanical energy. The device does not need additional direct current voltage driving and vacuum packaging when working, and can operate under normal atmospheric pressure. It has the advantages of direct frequency output and low power consumption, and does not need to process complex movable mechanical structures, so it is convenient for large-scale batch processing and preparation, and the manufacturing cost is low.

[0023] 2、The present application greatly reduces the mechanical constraint of the substrate on the free vibration of the electric field sensitive resonator by hollowing the silicon substrate and optimizing it with the A0 mode, i.e., suspending the main body of the electric field sensitive resonator above the substrate and connecting it to the substrate only through a pair of long strip-shaped anchors, while effectively reducing the leakage of acoustic energy by using the significant acoustic impedance difference between the main body of the resonator and the air.

[0024] 3、The present application increases the contact area between the piezoelectric film and the measured electric field, strengthens the coupling effect of the measured electric field and the resonator, and greatly improves the electric field sensitivity by controlling the ratio of the interdigital electrode area to the piezoelectric film area in the electric field sensitive resonator main body to 25% and locating the interdigital electrode at the center strain concentration position of the piezoelectric film, while achieving effective excitation of the required mode (A0). BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 A three-dimensional structure schematic diagram of the piezoelectric resonant electric field sensor based on the Lamb wave A0 mode provided for the embodiment is shown in the figure.

[0026] Figure 2 A three-dimensional exploded structure schematic diagram of the piezoelectric resonant electric field sensor based on the Lamb wave A0 mode provided for the embodiment is shown in the figure.

[0027] Figure 3 A top view structure schematic diagram of the piezoelectric resonant electric field sensor based on the Lamb wave A0 mode provided for the embodiment is shown in the figure.

[0028] Figure 4 A bottom view structure schematic diagram of the piezoelectric resonant electric field sensor based on the Lamb wave A0 mode provided for the embodiment is shown in the figure.

[0029] Figure 5 A curve diagram of the resonant frequency of the piezoelectric resonant electric field sensor based on the Lamb wave A0 mode provided for the embodiment shifting with the change of the vertical direction (Z axis) electric field intensity is shown in the figure.

[0030] Figure 6 A B-B' cross-sectional schematic diagram of the piezoelectric resonant electric field sensor based on the Lamb wave A0 mode provided for the embodiment is shown in the figure.

[0031] Figure 7 A0 mode piezoelectric resonant electric field sensor based on the Lamb wave provided for the embodiment of the input interdigital electrode and the output interdigital electrode of the exploded structure diagram;

[0032] Figure 8 A0 mode piezoelectric resonant electric field sensor based on the Lamb wave provided for the embodiment of the A0 mode vibration displacement graph of the B-B' cross section (not including the substrate part);

[0033] Figure 9 A0 mode piezoelectric resonant electric field sensor based on the Lamb wave provided for the embodiment of the electric field sensitivity change curve graph under different top interdigital electrode coverages;

[0034] Figure 10 A0 mode piezoelectric resonant electric field sensor based on the Lamb wave provided for the embodiment of the A0 mode vibration strain graph of the B-B' cross section (not including the substrate part);

[0035] Reference numerals:

[0036] 1, electric field sensitive resonator main body; 2, input interdigital electrode; 201, input metal electrode disc; 202, input metal transmission line; 203, first ground electrode disc; 204, first electrode widening area; 3, output interdigital electrode; 301, output metal electrode disc; 302, output metal transmission line; 303, second ground electrode disc; 304, second electrode widening area; 4, piezoelectric thin film; 5, first isolation oxide layer; 6, heavily doped single crystal silicon layer; 7, substrate; 701, second isolation oxide layer. DETAILED DESCRIPTION

[0037] Hereinafter, the term "include" or "may include" used in various embodiments of the present application indicates the existence of the invented function, operation, or element, and does not limit addition of one or more functions, operations, or elements. Also, as used in various embodiments of the present application, the terms "include", "have", and their conjugates merely indicate the presence of specific features, numbers, steps, operations, elements, components, or combinations thereof, and should not be construed as excluding the presence or addition of one or more other features, numbers, steps, operations, elements, components, or combinations thereof.

[0038] In various embodiments of the present application, the expression "or" or "at least one of A or / and B" includes any combination of the listed terms or all combinations thereof. For example, the expression "A or B" or "at least one of A or / and B" can include A, can include B, or can include both A and B.

[0039] The expressions used in the various embodiments of the present application, such as "first", "second", etc., can modify various constituent elements in the various embodiments, but can not limit the corresponding constituent elements. For example, the above expressions do not limit the order and / or importance of the elements. The above expressions are only for the purpose of distinguishing one element from other elements. For example, the first user device and the second user device indicate different user devices, although both are user devices. For example, without departing from the scope of the various embodiments of the present application, a first element can be referred to as a second element, and likewise, a second element can be referred to as a first element.

[0040] It should be noted that if a description connects one constituent element to another constituent element, the first constituent element can be directly connected to the second constituent element, and a third constituent element can be "connected" between the first constituent element and the second constituent element. Conversely, when one constituent element is "directly connected" to another constituent element, it can be understood that there is no third constituent element between the first constituent element and the second constituent element.

[0041] The terms used in the various embodiments of the present application are only for the purpose of describing specific embodiments and are not intended to limit the various embodiments of the present application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the various embodiments of the present application belong. The terms such as those defined in a generally used dictionary will be interpreted as having the same meaning as the contextual meaning in the relevant technical field and will not be interpreted as having an idealized or overly formal meaning, unless clearly defined in the various embodiments of the present application.

[0042] To make the purposes, technical solutions and advantages of the present application clearer, further detailed description of the present application will be made below in conjunction with embodiments and drawings, the illustrative embodiments of the present application and their descriptions are only for the purpose of explaining the present application and not as a limitation of the present application. The technical solutions of the present application will be described in detail below in conjunction with the drawings.

[0043] Example 1

[0044] For ease of understanding, the professional technical terms appearing in this text will be explained first as follows:

[0045] Acoustic impedance: used to measure the size of the resistance encountered by sound waves when propagating in different media, reflecting the hindering effect of the medium on sound waves, similar to the hindering effect of electrical resistance on electric current, when sound waves propagate from one medium to another medium with a large difference in acoustic impedance (such as silicon and air), the sound waves will produce a strong reflection phenomenon.

[0046] Piston structure: a special structure design for interdigital electrodes, the core idea of which is to change the phase velocity of sound waves in the end region of the electrode by increasing the equivalent mass load in this region, thereby suppressing the spurious modes excited by the interdigital electrodes in the resonator.

[0047] Spurious mode: a non-ideal vibration mode of the resonator excited by the interdigital electrodes, which will interfere with the frequency response of the resonator and affect the normal operation of the resonator.

[0048] Phase velocity: the propagation speed of the phase of a sound wave in a medium.

[0049] Positive piezoelectric effect: when a piezoelectric material is subjected to an external force in a certain direction, it will polarize due to the non-symmetry of the crystal structure of the piezoelectric material, and an electric charge with opposite polarity will be generated on the surface of the piezoelectric material.

[0050] Inverse piezoelectric effect: when an alternating electric field is applied to the surface of a piezoelectric material, the material will undergo mechanical deformation, and the size of the deformation is closely related to the strength of the applied electric field.

[0051] As shown in Figures 1-4 The piezoelectric resonator-based electric field sensor based on the A0 mode of Lamb waves provided by the present example includes a substrate 7 and an electric field-sensitive resonator body 1, an input metal electrode disc 201 and an input metal transmission line 202, an output metal electrode disc 301 and an output metal transmission line 302, a first ground electrode disc 203 and a second ground electrode disc 303 integrated on the substrate 7.

[0052] The substrate 7 is composed of two layers of single crystal silicon layers tightly adhered to each other, and a full-coverage second isolation oxide layer 701 is embedded between the two layers of single crystal silicon layers, forming a sandwiched laminated structure, and a through hole is provided in the structure, which penetrates through the two layers of single crystal silicon layers and the second isolation oxide layer 701 in the middle, constituting a hollow area.

[0053] The electric field-sensitive resonator body 1 is suspended in the hollow area and connected to the substrate 7 at both ends through an anchor point. The electric field-sensitive resonator body 1 is composed of an input interdigital electrode 2, an output interdigital electrode 3, a piezoelectric film 4 and a heavily doped single crystal silicon layer 6 arranged from top to bottom.

[0054] The input metal transmission line 202 is connected to the input interdigital electrode 2 at one end and to the input metal electrode plate 201 at the other end. The output metal transmission line 302 is connected to the output interdigital electrode 3 at one end and to the output metal electrode plate 301 at the other end. The input metal transmission line 202 and the output metal transmission line 302 are both composed of a transmission segment and a transition segment. The transmission segment is located on the upper surface of the substrate layer, and the transition segment is located on the upper surface of the piezoelectric thin film. One end of the transmission segment in the input metal transmission line 202 is connected to one end of the transition segment, and the other end is connected to the input electrode plate 201. The other end of the transition segment is connected to the input interdigital electrode 2. One end of the transmission segment in the output metal transmission line 302 is connected to one end of the output transmission line transition segment, and the other end is connected to the output electrode plate 301. The other end of the output transmission line transition segment is connected to the output interdigital electrode 3.

[0055] The input metal electrode plate 201 and the output metal electrode plate 301 are both located on the upper surface of the substrate 7. Each side of the input metal electrode plate 201 is provided with a first ground electrode plate 203, and each side of the output metal electrode plate is also provided with a second ground electrode plate 303.

[0056] A first isolation oxide layer 5 is provided below all the metal electrode plates and the transmission segments of the metal transmission lines, which is electrically isolated from the substrate 7.

[0057] In this embodiment, the piezoelectric thin film 4 is a rectangular piezoelectric material thin film deposited by a vacuum sputtering method. The anchor point is a long strip structure at the connection between the resonator body and the substrate, which reduces the constraint of the substrate on the free-vibration resonator body. At the same time, the acoustic impedance difference between the resonator body and the air causes the reflection of acoustic waves at the resonator boundary, thereby concentrating acoustic wave energy in the resonator body. The total area of the input interdigital electrode 2 and the output interdigital electrode 3 is 25% of the total area of the piezoelectric thin film. This ensures that the A0 mode can be normally excited, and at the same time, it allows a larger contact area between the piezoelectric thin film and the measured electric field, thereby enhancing the coupling between the measured electric field and the resonator body and improving the sensitivity of the electric field measurement. At the same time, the entire interdigital electrode is located at the central strain concentration position of the piezoelectric thin film 4. The strain concentration position is the position where the strain size is significantly different from the surrounding positions in the A0 mode vibration strain diagram, as shown in Figure 10The interdigital electrode is arranged at the strain concentration position of the piezoelectric film, so that the interdigital electrode can more effectively excite the electric field sensitive resonator according to the vibration shape of the A0 mode, and unnecessary energy loss is reduced. Moreover, the piezoelectric film under the gap between the input interdigital electrode and the output interdigital electrode is etched, so that the piezoelectric film forms a periodic groove structure in the direction perpendicular to the interdigital electrode, the electric field concentration degree of the groove area is enhanced, greater strain can be generated in the piezoelectric film, and the electric field sensitivity is improved. The first electrode widening area 204 and the second electrode widening area 304 are arranged at the ends of the input interdigital electrode and the output interdigital electrode respectively to form a piston structure, so as to increase the equivalent mass load of the area caused by the electrode and then reduce the phase velocity of the Lamb wave of the area. At this time, the acoustic impedance difference of the original electrode end is changed, and the generation of the spurious mode is reduced. It should be noted that the center strain concentration position of the piezoelectric film 4 can be obtained in various ways, and in this embodiment, the center strain concentration position is obtained through simulation.

[0058] The resonator adopting the TPoS structure is a two-port acoustic device capable of realizing mutual conversion between mechanical energy and electric energy. When a voltage is applied to the input interdigital electrode 2 to generate excitation, the piezoelectric film 4 will be affected by the electric field generated by the input interdigital electrode 2. At this time, due to the inverse piezoelectric effect, mechanical strain is generated in the piezoelectric material, and the entire resonator is driven to vibrate according to a specific vibration mode, realizing the conversion from electric energy to mechanical energy. The output interdigital electrode 3 located on the piezoelectric film 4 will collect the periodic induced charge generated by the piezoelectric film 4 due to strain under the action of the positive piezoelectric effect, and finally output through the output metal transmission line 302 and the output metal electrode disc 301.

[0059] As shown in Figure 4 , the electric field sensor shown in the application is realized by detecting the inherent resonance frequency of the electric field sensitive resonator body. When there is no external electric field in the space, the inherent frequency of the resonator is determined by its geometric size and the material properties of the resonator itself. The expression of the inherent frequency f0 is:

[0060]

[0061] In the formula, t is the thickness of the resonator, C0 is the total elastic stiffness coefficient of the resonator, p0 is the total density of the resonator, V p is the phase velocity of the acoustic wave propagation. When an electric field consistent with the thickness direction (Z-axis) is applied to the resonator, the piezoelectric response to the thickness direction in the piezoelectric material is excited, and the expression of the excited longitudinal strain ε z is:

[0062] ε z = d 33 E z

[0063] where d 33 is the component of piezoelectric constant matrix in the thickness direction (Z axis) of piezoelectric material, E z is the magnitude of applied Z axis electric field intensity, and the longitudinal strain ε z will introduce longitudinal prestress σ z , thereby modulating the total elastic stiffness coefficient of the resonator, eventually leading to the shift of the natural resonant frequency of the resonator, and the expression of frequency shift Δf is:

[0064]

[0065] C1 = ∫σ z · ε z dV = E z ∫σ z · d 33 dV

[0066] where C1 is the elastic stiffness coefficient after longitudinal electric field modulation, and f1 is the natural resonant frequency value after the action of longitudinal electric field. According to the above formula, it can be found that the frequency response of the electric field sensitive resonator shows linear shift to the applied electric field intensity, so by using the characteristic that the resonant frequency of the resonator presents linear change with the applied electric field intensity (see Figure 5 ), only the change amount of the resonant frequency of the whole resonator needs to be measured to know the magnitude of the applied electric field intensity.

[0067] As shown in Figure 8 , Lamb wave is an elastic guided wave propagating in a free boundary thin plate, and the propagation direction is parallel to the plate surface and the energy is confined in the plate. A0 mode is one of the basic modes of Lamb wave propagation, and its characteristic is that the displacement is antisymmetrically distributed along the plate thickness direction, the central surface displacement is zero and the displacement amplitude of the upper and lower surfaces is maximum. A0 mode is sensitive to the change of thickness direction strain distribution, and can produce frequency shift response to the small disturbance caused by the thickness direction electric field.

[0068] As shown in Figure 6 , 7 , 9, the present application adopts the optimal ratio of surface interdigital electrode to piezoelectric film area. Compared with the resonator structure in which interdigital electrodes are arranged above the traditional piezoelectric film, the use of the structure can greatly improve the sensitivity of the resonator to the applied electric field, increase the coupling effect between the external electric field and the resonator, and at the same time ensure the normal excitation of A0 mode. The top interdigital electrode coverage η is defined as:

[0069]

[0070] In the formula, S IDT is the area of the top interdigital electrode, and S Piezo is the area of the piezoelectric film.

[0071] Compared with a conventional piezoelectric thin film resonator structure with uniform thickness, the piezoelectric thin film under the gap region of the input interdigital electrode and the output interdigital electrode is etched to form a periodic groove structure, so that the external electric field is concentratedly distributed in the groove region, the strain generated in the piezoelectric thin film by the external electric field is greatly improved, and the electric field sensitivity is improved.

[0072] In general, the piezoelectric resonant electric field sensor based on the Lamb wave A0 mode realizes the detection of the external electric field strength without the need of processing a complex mechanical movable structure, and has the advantages of not needing vacuum packaging and high sensitivity.

[0073] The above embodiments only exemplarily illustrate the principles and effects of the present application, and are not used to limit the present application. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical thought of the present application should be covered by the claims of the present application.

Claims

1. A piezoelectric resonant electric field sensor based on the Lamb wave A0 mode, characterized in that, It includes a substrate, an electric field-sensitive resonator body, an input metal transmission line, an output metal transmission line, an input metal electrode disk, and an output metal electrode disk; The substrate is composed of two tightly bonded monocrystalline silicon layers, with a second isolation oxide layer sandwiched between the two monocrystalline silicon layers, forming a sandwich-like stacked structure. The structure has a through hole that penetrates the two monocrystalline silicon layers and the middle second isolation oxide layer, forming a hollow area. The main body of the electric field-sensitive resonator is suspended in the hollowed-out area, with each end connected to the substrate via an anchor point. The main body consists of an input interdigital electrode, an output interdigital electrode, a piezoelectric thin film, and a heavily doped single-crystal silicon layer, arranged sequentially from top to bottom. Both the input and output interdigital electrodes are made of identical polygonal metal sheets, arranged symmetrically and alternately on the piezoelectric thin film, with an overall size smaller than the film. The width of the electrode strips is widened at the ends of the input and output interdigital electrodes, forming a piston structure. The input and output interdigital electrodes are located at the center of the piezoelectric thin film where strain is concentrated. Selective etching is performed on the piezoelectric thin film beneath the gaps between the input and output interdigital electrodes, creating a periodic groove structure on the side of the piezoelectric thin film in contact with the interdigital electrodes. The total area of ​​the input and output interdigital electrodes is 25% of the total area of ​​the piezoelectric thin film. One end of the input metal transmission line is connected to the input interdigitated electrode, and the other end is connected to the input metal electrode disk; one end of the output metal transmission line is connected to the output interdigitated electrode, and the other end is connected to the output metal electrode disk; both the input and output metal transmission lines consist of a transmission section and a transition section; the transmission section is located on the upper surface of the substrate, with one end connected to one end of the transition section and the other end connected to the metal electrode disk; the transition section is located on the upper surface of the piezoelectric film, with the other end connected to the interdigitated electrode; both the input and output metal electrode disks are located on the upper surface of the substrate, with a grounded metal disk on each side of the input metal electrode disk and a grounded metal disk on each side of the output metal electrode disk; A first isolation oxide layer, electrically isolated from the substrate, is provided beneath all metal electrode disks and transmission sections of metal transmission lines.

2. The piezoelectric resonant electric field sensor based on the Lamb wave A0 mode according to claim 1, characterized in that, The first and second isolation oxide layers are both made of silicon dioxide, and both have a thickness of 0.3 μm to 1.5 μm.

3. The piezoelectric resonant electric field sensor based on the Lamb wave A0 mode according to claim 1, characterized in that, The anchor point is a long strip-shaped structure at the connection between the resonator body and the substrate.

4. A piezoelectric resonant electric field sensor based on the Lamb wave A0 mode according to any one of claims 1-3, characterized in that, The metal transmission line, metal electrode disk, and interdigitated electrode are made of gold, silver, copper, aluminum, nickel, or platinum, and the thickness of the metal transmission line, metal electrode disk, and interdigitated electrode is 0.2 μm to 2 μm; the thickness of the piezoelectric film is 0.1 μm to 1 μm.

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