Field mill direct current modulation and coil induction integrated MEMS electric field sensor

Abstract

The invention discloses a field-grinding direct-current modulation and coil induction integrated MEMS electric field sensor, and the sensor comprises a spiral coil induction electrode which is disposed on an SOI substrate, and converts the periodic change of an alternating-current electric field into a first signal; the comb tooth electrode structure is fixedly arranged on the SOI substrate and comprises a piezoelectric driving structure, at least two movable shielding electrodes and at least two fixed induction electrodes, and the piezoelectric driving structure is fixedly connected with the SOI substrate; the movable shielding electrode is elastically connected with the piezoelectric driving structure and generates periodic vertical displacement under the driving of the piezoelectric driving structure; the fixed induction electrode and the movable shielding electrode are correspondingly arranged to form an electrode group, and the low-frequency alternating-current and direct-current electric fields are modulated and converted into second signals. The invention has the beneficial effects that the full-band measurement of direct-current, low-frequency and high-frequency signals is realized, the measurement frequency range of the sensor is widened, the processing difficulty and the manufacturing cost are reduced, and the production efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of micro electric field sensors, and more particularly, to a field mill DC modulation and coil induction integrated MEMS electric field sensor. Background Art

[0002] Voltage sensing is crucial for power systems. Existing mainstream voltage measurement technologies have many problems. For example, technical devices based on capacitance, resistance, and resistance-capacitance voltage division are large in size, have few distribution points, are easily affected by stray capacitance and temperature, have poor transient performance, and are easily damaged by harmonics; technologies based on leakage current measurement have high requirements for sensor accuracy and are easily affected by noise, making it impossible to guarantee accuracy; technologies based on optical sensing have not been widely applied due to high process requirements for optical devices and large temperature influence; field mill type MEMS electric field sensors mainly use electrostatic drive and thermal drive technologies, but they have problems such as large influence of the measured electric field distortion, high drive voltage, insufficient accuracy and sensitivity.

[0003] As a new technical means, the piezoelectric drive method has significant advantages of low drive voltage and low interference in theory, providing a new idea for solving the above problems. However, this technology is still limited by the mechanical structure resonance frequency in practical applications and has certain limitations in high-frequency alternating current electric field measurement. Summary of the Invention

[0004] To solve the above problems, the purpose of the present invention is to provide a field mill DC modulation and coil induction integrated MEMS electric field sensor.

[0005] The present invention provides a field mill DC modulation and coil induction integrated MEMS electric field sensor, including:

[0006] A spiral coil induction electrode, fixedly arranged on an SOI substrate, sensing the surrounding external electric field and converting the periodic change of the alternating current electric field into a first signal;

[0007] A comb tooth electrode structure, fixedly arranged on the SOI substrate, including a piezoelectric drive structure, at least two movable shielding electrodes, and at least two fixed induction electrodes. Among them, the piezoelectric drive structure is fixedly connected to the SOI substrate, receiving a periodic voltage drive signal and generating a periodic mechanical deformation; the movable shielding electrode is elastically connected to the piezoelectric drive structure and generates a periodic vertical displacement under the drive of the piezoelectric drive structure; the fixed induction electrode is correspondingly arranged with the movable shielding electrode to form an electrode group and is fixedly connected to the SOI substrate, sensing the surrounding external electric field and converting the modulation of low-frequency alternating current and direct current electric fields into a second signal.

[0008] As a further improvement of the present invention, the fixed induction electrode includes a plurality of fixed comb tooth groups symmetrically distributed, and the comb tooth array of each fixed comb tooth group extends from the central region to the edge along the radial direction of the SOI substrate; the movable shielding electrode includes a plurality of movable comb tooth groups correspondingly arranged, and the comb tooth array of each movable comb tooth group extends from the edge to the central along the radial direction of the SOI substrate, forming an interleaved nested structure with the fixed comb tooth group.

[0009] As a further improvement of the present invention, the voltage driving signal is composed of a forward driving voltage and a reverse driving voltage with equal magnitudes and a phase difference of 180°, which are respectively applied to the piezoelectric driving structures corresponding to the symmetrically distributed fixed induction electrodes.

[0010] As a further improvement of the present invention, the piezoelectric driving structure is a piezoelectric cantilever beam structure, which is composed of an upper metal electrode, a piezoelectric material layer and a lower metal electrode.

[0011] As a further improvement of the present invention, the piezoelectric material layer is made by sol-gel film forming method, chemical solution deposition method, chemical vapor deposition method or magnetron sputtering deposition method.

[0012] As a further improvement of the present invention, the SOI substrate includes a top silicon layer, a buried oxide layer and a bottom silicon layer arranged in sequence from top to bottom.

[0013] As a further improvement of the present invention, the spiral coil induction electrode, the piezoelectric driving structure and the fixed induction electrode are welded on the top silicon layer.

[0014] As a further improvement of the present invention, an insulating layer is provided between the spiral coil induction electrode and the top silicon layer.

[0015] As a further improvement of the present invention, the spiral coil induction electrode is arranged at the center of the SOI substrate.

[0016] As a further improvement of the present invention, at least two electrode groups are arranged around the spiral coil induction electrode.

[0017] The beneficial effects of the present invention are as follows: By arranging a spiral coil induction electrode and a comb tooth electrode structure on the SOI substrate, using the spiral coil induction electrode to measure alternating current and the resonant part of the comb tooth electrode structure to measure direct current, the full-band measurement of direct current, low-frequency and high-frequency signals is realized, greatly broadening the measurement frequency range of the sensor and effectively solving the problem of limited alternating current bandwidth. And this integrated design simplifies the preparation process, reduces the processing difficulty and manufacturing cost, and improves the production efficiency. Description of the Drawings

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0019] Figure 1 FIG. 4 is a schematic structural diagram of a field mill DC modulation and coil induction integrated MEMS electric field sensor according to an exemplary embodiment of the present invention;

[0020] Figure 2 FIG. 5 is a simulation diagram of a field mill DC modulation and coil induction integrated MEMS electric field sensor according to an exemplary embodiment of the present invention.

[0021] In the figure,

[0022] 1. Spiral coil induction electrode; 2. SOI substrate; 3. Piezoelectric drive structure; 4. Movable shielding electrode; 5. Fixed induction electrode; 6. Top silicon layer; 7. Buried oxide layer; 8. Bottom silicon layer; 9. AC induction electrode solder joint; 10. Drive electrode solder joint; 11. Induction electrode solder joint; 12. Movable comb tooth group; 13. Fixed comb tooth group. Detailed implementation manners

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0024] It should be noted that if there are directional indications (such as up, down, left, right, front, back...) involved in the embodiments of the present invention, the directional indications are only used to explain the relative position relationship and movement conditions between components in a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0025] In addition, in the description of the present invention, the terms used are for illustrative purposes only and are not intended to limit the scope of the present invention. The terms "comprising" and / or "including" are used to specify the presence of the described elements, steps, operations, and / or components, but do not exclude the presence or addition of one or more other elements, steps, operations, and / or components. The terms "first", "second", etc. may be used to describe various elements, do not represent an order, and do not limit these elements. In addition, in the description of the present invention, unless otherwise specified, "a plurality of" means two or more. These terms are only used to distinguish one element from another. In conjunction with the following drawings, these and / or other aspects become apparent, and it is easier for those of ordinary skill in the art to understand the description of the embodiments of the present invention. The drawings are only used to depict the embodiments of the present invention for illustrative purposes. Those skilled in the art will easily recognize from the following description that alternative embodiments of the structure and method shown in the present invention can be adopted without departing from the principles described in the present invention.

[0026] Embodiment 1, as Figure 1 shown, a field mill DC modulation and coil induction integrated MEMS electric field sensor according to an embodiment of the present invention includes:

[0027] A spiral coil induction electrode 1, fixedly arranged on an SOI substrate 2, senses the surrounding external electric field and converts the periodic change of the alternating current electric field into a first signal;

[0028] A comb-tooth electrode structure, fixedly arranged on the SOI substrate 2, includes a piezoelectric drive structure 3, at least two movable shielding electrodes 4, and at least two fixed induction electrodes 5. Among them, the piezoelectric drive structure 3 is fixedly connected to the SOI substrate 2, receives a periodic voltage drive signal and generates a periodic mechanical deformation; the movable shielding electrode 4 is elastically connected to the piezoelectric drive structure 3 and generates a periodic vertical displacement under the drive of the piezoelectric drive structure 3; the fixed induction electrode 5 is correspondingly arranged with the movable shielding electrode 4 to form an electrode group, and is fixedly connected to the SOI substrate 2, senses the surrounding external electric field, and converts the modulation of low-frequency alternating current and direct current electric fields into a second signal.

[0029] Among them, the first signal is an alternating current periodic signal, and the second signal is a low-frequency alternating current and direct current signal.

[0030] When using the sensor of the present application, first, a periodic voltage drive signal is applied to the piezoelectric drive structure 3. Utilizing the inverse piezoelectric effect, it generates bending vibration, and further drives the movable shielding electrode 4 to generate a vertical displacement. Combining the field mill DC modulation measurement principle and the electric field edge effect, when the relative position between the movable shielding electrode 4 and the fixed induction electrode 5 changes, the amount of charge induced on the fixed induction electrode 5 will show periodic fluctuations accordingly, and then a second signal proportional to the external electric field to be measured is generated. By measuring this signal, the measurement of DC electric fields and some medium- and low-frequency AC electric fields can be achieved. Among them, the field mill DC modulation measurement principle is similar to that of the field mill. At the same time, in view of the characteristic that the external AC electric field changes with time, the external electric field to be measured where the spiral coil induction electrode 1 is located will also show periodic changes in strength. According to the basic principle of electromagnetic induction, this periodic change will cause the spiral coil induction electrode 1 to generate a first signal proportional to the external AC electric field to be measured. By measuring this signal, the measurement of high-frequency AC electric fields can be achieved.

[0031] The specific measurement principle is as follows:

[0032] When the measured electric field E is perpendicular to the upper part of the induction electrode (including the fixed induction electrode 5 and the spiral coil induction electrode 1), induced charges are generated on the surface of the induction electrode. According to Gauss's theorem, the induced charge Q is:

[0033] Q = εEA (1)

[0034] Where, A is the effective induction area, and ε is the permittivity of the space around the sensitive structure of the induction electrode.

[0035] (1) DC electric field measurement

[0036] In the measurement of the DC electric field E dc After the sensor receives the excitation signal generated by the voltage drive signal, the movable shielding electrode 4 will vibrate periodically back and forth. Let the frequency of the excitation signal be ω s , and the initial phase A0 is the maximum exposed area of the movable shielding electrode 4. Then the effective induction area, that is, the exposed area A, of the fixed induction electrode 5 can be expressed as:

[0037]

[0038] Where, t is the time variable.

[0039] Under vibration modulation, the external electric field to be measured will be converted into induced charges carrying the information of the external electric field, and the frequency of the charge quantity change is the same as the AC part frequency ω s of the voltage drive signal. The induced charge on the fixed induction electrode 5 is:

[0040]

[0041] The periodic change of the induced charge on the fixed induction electrode 5 generates an induced current. After I / V conversion, the output voltage signal U is as follows:

[0042]

[0043] where R f is the resistance of the conversion circuit.

[0044] The modulated voltage signal U can be used to characterize the DC electric field to be measured.

[0045] (2) AC electric field measurement

[0046] When placed in an AC electric field, the spiral coil induction electrode 1 can generate an induced current. Assuming the amplitude of the AC electric field is E m , then the AC electric field strength E to be measured ac can be expressed as:

[0047]

[0048] where ω e is the frequency of the AC electric field, is the initial phase of the AC electric field.

[0049] Substituting into Equation (1), it can be obtained that in the AC electric field induction environment, under the condition of the highest induction efficiency, the induced charge quantity Q of the spiral coil induction electrode 1 is:

[0050]

[0051] The change of the induced charge quantity causes an induced current, and after transresistance, the output voltage signal U is:

[0052]

[0053] During the measurement of the AC electric field, U represents the output voltage value of the sensor under different AC electric fields. By calibrating the sensor through a standard electric field platform, the AC electric field to be measured can be characterized, thus achieving the purpose of detecting the AC electric field.

[0054] In this application, by setting the spiral coil induction electrode 1 and the comb electrode structure on the SOI substrate 2, using the spiral coil induction electrode 1 to measure AC and the resonant part of the comb electrode structure to measure DC, the full-band measurement of DC, low-frequency, and high-frequency signals is realized, greatly broadening the measurement frequency range of the sensor and effectively solving the problem of limited AC bandwidth. And this integrated design simplifies the preparation process, reduces the processing difficulty and manufacturing cost, and improves the production efficiency.

[0055] At least two movable shielding electrodes 4 and at least two fixed induction electrodes 5 are provided. Each movable shielding electrode 4 and each fixed induction electrode 5 are provided in a matching manner, and a movable shielding electrode 4 and a fixed induction electrode 5 form an electrode group.

[0056] The arrangement positions of the electrode groups and the spiral coil induction electrode 1 on the SOI substrate 2 can be designed according to requirements. For example, the spiral coil induction electrode 1 can be arranged at the center or the edge of the SOI substrate 2. At least two electrode groups are symmetrically arranged on both sides of the spiral coil induction electrode 1. The above two sides can be understood as the two sides in the length direction of the spiral coil induction electrode 1, or the two sides in the width direction, or the two sides of the diagonal. It can also be understood that at least two electrode groups are arranged on both sides of the spiral coil induction electrode 1, but not symmetrically. For example, the spiral coil induction electrode 1 can be arranged at the center of the SOI substrate 2, and at least two electrode groups are arranged on one side of the spiral coil induction electrode 1. The above one side can be understood as one side in the length direction of the spiral coil induction electrode 1, or one side in the width direction. It can also be understood that at least two electrode groups are symmetrically arranged on one side of the spiral coil induction electrode 1.

[0057] It can also be understood that the number of the electrode groups can also be adaptively designed. For example, three electrode groups are arranged and distributed around the spiral coil induction electrode 1. Among them, each electrode group can be respectively arranged on different sides of the spiral coil induction electrode 1, or two electrode groups can be arranged on one side of the spiral coil induction electrode 1, and the other electrode group can be arranged on the other side of the spiral coil induction electrode 1. It is also possible that all three electrode groups are arranged on one side of the spiral coil induction electrode 1. For example, four electrode groups are arranged and distributed around the spiral coil induction electrode 1. The arrangement position of each electrode group can be freely selected and will not be elaborated here.

[0058] Preferably, the spiral coil induction electrode 1 is arranged at the center of the SOI substrate, and at least two electrode groups are arranged symmetrically on both sides of the spiral coil induction electrode 1. More preferably, four electrode groups are arranged, and the four electrode groups are symmetrically arranged around the spiral coil induction electrode 1, as Figure 2As shown, the spiral coil induction electrode 1 is disposed at the center of the SOI substrate, and two electrode groups are located on one side of the length direction of the spiral coil induction electrode 1, and the other two electrode groups are located on the other side of the length direction of the spiral coil induction electrode 1, and the four electrode groups are symmetrically arranged. It can be understood that by disposing the spiral coil induction electrode 1 at the center of the SOI substrate and arranging the electrode groups on the periphery of the spiral coil induction electrode 1 and symmetrically, on the one hand, as many electrode groups as possible can be arranged in a limited space, improving the measurement accuracy and sensitivity, and on the other hand, the close arrangement of the electrode groups and the spiral coil induction electrode can also reduce the product size.

[0059] Preferably, the movable shielding electrode 4 is connected to the piezoelectric driving structure 3 through an elastic beam, and the vertical displacement of the piezoelectric driving structure 3 is efficiently converted into the vertical displacement of the movable shielding electrode 4 to ensure that the movable shielding electrode 4 moves stably according to the vibration law of the piezoelectric driving structure 3, guaranteeing the measurement accuracy.

[0060] In one implementation, the fixed induction electrode 5 includes a plurality of fixed comb tooth groups 13 symmetrically distributed, and the comb tooth array of each fixed comb tooth group 13 extends from the central region to the edge along the radial direction of the SOI substrate 2; the movable shielding electrode 4 includes a plurality of movable comb tooth groups 12 correspondingly arranged, and the comb tooth array of each movable comb tooth group 12 extends from the edge to the center along the radial direction of the SOI substrate 2, forming an interleaved nested structure with the fixed comb tooth group 13.

[0061] Among them, to ensure the accuracy and symmetry of electric field induction, the number of comb teeth of the fixed induction electrode 5 and the movable shielding electrode 4 should be matched. Preferably, the number of comb teeth of each movable comb tooth group 12 should be more than the number of comb teeth of the corresponding fixed comb tooth group 13 to make the electric field distribution more uniform and further improve the measurement accuracy. For example Figure 1 As shown, in one electrode group, the movable comb tooth group 12 is provided with 7 comb teeth, and the fixed comb tooth group 13 is provided with 6 comb teeth. When the movable comb tooth group 12 and the fixed comb tooth group 13 are interleaved and nested, the movable comb tooth group 12 can form a surrounding circle to completely cover the area where the fixed comb tooth group 13 is located, thereby reducing the measurement error caused by uneven electric field distribution and improving the measurement accuracy.

[0062] Preferably, each movable comb tooth group 12 is connected to at least two piezoelectric drive structures 3. This can not only maintain a relatively stable vibration state of the movable shielding electrode 4, enhance the stability and uniformity of the vibration of the movable comb tooth group 12, improve the measurement accuracy and reliability, but also avoid affecting the normal vibration of the entire movable comb tooth group 12 and the realization of the corresponding functions due to the failure or performance fluctuation of a single piezoelectric drive structure 3. It can be understood that the number of piezoelectric drive structures 3 connected to the movable comb tooth group 12 can be adjusted according to the actual situation, and the present application does not make specific limitations in this regard.

[0063] Preferably, the tooth pitch between the movable comb tooth group 12 and the fixed comb tooth group 13 is 5 - 10 μm. When the tooth pitch is too large, the induction area between the fixed induction electrode 5 and the movable shielding electrode 4 will be reduced within a limited space, thereby reducing the sensitivity of the sensor and affecting the detection ability of weak electric field signals. When the tooth pitch is too small, the Pull effect between the fixed induction electrode 5 and the movable shielding electrode 4 will be triggered, that is, abnormal adsorption occurs between the two electrodes due to the too-close distance. This will not only interfere with the normal induction and measurement process of the sensor for the electric field, but may also cause physical contact between the electrodes, resulting in electrode damage, reducing the reliability and service life of the sensor, and significantly increasing the manufacturing difficulty of the sensor, raising the production cost and production cycle, and reducing the production efficiency.

[0064] It can be understood that the number of teeth and the tooth pitch of the fixed induction electrode 5 and the movable shielding electrode 4 can be adjusted according to the actual situation, and the present application does not make specific limitations in this regard. For example, in some scenarios with high requirements for measurement accuracy and relatively stable application environments, a smaller tooth pitch can be used to ensure sufficient induction area to maintain high sensitivity. In some scenarios with relatively low requirements for sensitivity but strict restrictions on the size of the sensor, a larger tooth pitch can be used to effectively reduce the pull-in behavior (Pull effect) in the MEMS system while meeting the basic measurement requirements, and rationally layout the electrode structure within the limited space to further improve the stability and working efficiency of the sensor.

[0065] Furthermore, the voltage drive signal is composed of a forward drive voltage and a reverse drive voltage that are equal in magnitude and have a phase difference of 180°, and they act on the piezoelectric drive structures corresponding to the symmetrically distributed fixed induction electrodes respectively. When a forward drive voltage is applied to the piezoelectric drive structures 3 on the same side and a reverse drive voltage with the same magnitude and a phase difference of 180° is applied to the other side, the surrounding external electric field will be in a vibration modulation mode. In this mode, the sensor can not only detect weak changes in the external electric field more sensitively, but also effectively suppress external interference, improve the measurement accuracy and stability, and thus better meet the high-precision requirements for electric field measurement in different application scenarios.

[0066] For example, as Figure 2 shown, a positive driving voltage is applied to the piezoelectric driving structure 3 on the left side, and a negative driving voltage is applied to the piezoelectric driving structure 3 on the right side. At this time, the two groups of moving comb teeth groups 12 on the left side will generate a vertically downward displacement driven by the piezoelectric driving structure 3, while the two groups of moving comb teeth groups 12 on the right side will generate a vertically upward displacement driven by the piezoelectric driving structure 3, so that the surrounding external electric field will be in a vibration modulation mode.

[0067] In one embodiment, the piezoelectric driving structure 3 is a piezoelectric cantilever beam structure, which is composed of an upper metal electrode, a piezoelectric material layer, and a lower metal electrode. The upper metal electrode and the lower metal electrode sandwich the piezoelectric material layer. When a voltage is applied between the upper metal electrode and the lower metal electrode, an electric field is formed, and under the action of the electric field, the piezoelectric material will undergo mechanical deformation according to the inverse piezoelectric effect.

[0068] Preferably, the piezoelectric material is lead zirconate titanate, doped modified lead zirconate titanate, lead magnesium niobate, aluminum nitride, etc. It can be understood that the piezoelectric material can be one or a combination of the above materials, and it can be adjusted according to the actual situation. This application does not make specific limitations in this regard.

[0069] In one embodiment, the piezoelectric material layer is made by sol-gel film forming method, chemical solution deposition method, chemical vapor deposition method or magnetron sputtering deposition method.

[0070] Among them, the composition of the sol-gel film-forming method is flexible and controllable. By adjusting the chemical composition in the precursor solution, the film composition and thickness can be accurately controlled. At the same time, the sol-gel film-forming method forms films by means such as solution impregnation, spin coating, and spraying, which can uniformly cover irregular surfaces and be applied to substrates with complex shapes and large areas at a relatively low cost. The chemical solution deposition method has strong process adaptability and can be applied to a variety of material systems, including but not limited to inorganic compounds, organic polymer materials, and composite materials, etc. It can be uniformly coated on non-planar or complex-shaped substrates, and the equipment is easy to operate and maintain, reducing the overall equipment investment cost. The chemical vapor deposition method can accurately control the film thickness by finely adjusting key parameters such as the flow rate of gaseous precursors, the pressure, temperature, and deposition time in the reaction chamber. At the same time, the entire deposition process involves chemical reactions and material deposition at the atomic and molecular levels, so it can also accurately adjust and control the microscopic properties such as the atomic structure and composition uniformity of the film to provide a reliable microscopic structure basis for stable and high-performance operation. Moreover, the chemical vapor deposition method can make the gaseous precursors react and deposit uniformly on the entire large-area substrate, thereby preparing a film with uniform thickness, consistent composition, and stable performance. The magnetron sputtering deposition method has strong wear resistance and corrosion resistance. By adjusting sputtering parameters such as power, gas pressure, and substrate temperature, it can accurately control the film structure and performance. At the same time, the magnetron sputtering deposition method can deposit a variety of materials, such as metals, alloys, oxides, nitrides, carbides, etc., and then realize the preparation of multifunctional composite films. It can be understood that the method for preparing the piezoelectric material layer can be adjusted according to the actual situation, and the present application does not make specific limitations in this regard.

[0071] In one implementation, the SOI substrate 2 includes a top silicon layer 6, a buried oxide layer 7, and a bottom silicon layer 8 that are sequentially arranged from top to bottom.

[0072] Among them, the thickness of the top silicon layer 6 needs to be determined according to the thickness of the silicon layer in the sensor to facilitate the processing of the piezoelectric drive structure 3. For example, when the width of the piezoelectric drive structure 3 is designed to be 5 μm - 50 μm, the thickness of the top silicon layer 6 is preferably 1 μm - 10 μm to ensure that the piezoelectric drive structure 3 realizes deep aspect ratio release in the dry etching (DRIE) process.

[0073] Furthermore, the thickness of the buried oxide layer 7 is 1 μm - 5 μm. It can not only increase the structural stability of the SOI substrate 2 but also effectively avoid the problem of electrical interference between the top silicon layer 6 and the bottom silicon layer 8.

[0074] Furthermore, the thickness of the bottom silicon layer 8 is 200 μm - 400 μm to provide a stable supporting force for the sensor.

[0075] In one embodiment, the spiral coil induction electrode 1, the piezoelectric drive structure 3, and the fixed induction electrode 5 are welded to the top silicon layer.

[0076] Among them, AC induction electrode solder joints 9, drive electrode solder joints 10, and induction electrode solder joints 11 are provided on the top silicon layer 6. The spiral coil induction electrode 1, the piezoelectric drive structure 3, and the fixed induction electrode 5 are respectively welded to the top silicon layer 6 through the AC induction electrode solder joints 9, the drive electrode solder joints 10, and the induction electrode solder joints 11. By applying a DC bias and an AC sine drive voltage signal to the drive electrode solder joint 10, the piezoelectric drive structure 3 can be controlled to drive the movable shielding electrode 4 to generate periodic vertical displacement. The electric charge induced on the fixed induction electrode 5 will then show periodic fluctuations, thereby generating a second signal proportional to the external electric field to be measured. Measuring this signal through the induction electrode solder joint 11 can achieve the measurement of DC electric fields and some medium- and low-frequency AC electric fields. At the same time, in view of the characteristic that the external AC electric field changes with time, the external electric field to be measured where the spiral coil induction electrode 1 is located will also show periodic changes in intensity. According to the basic principle of electromagnetic induction, this periodic change will cause the spiral coil induction electrode 1 to generate a first signal proportional to the external AC electric field to be measured. Measuring this signal through the AC induction electrode solder joint 9 can achieve the measurement of high-frequency AC electric fields.

[0077] Among them, the number of drive electrode solder joints 10 matches the number of piezoelectric drive structures 3. The induction electrode solder joints 11 connected to the fixed induction electrode 5 are preferably integrated into two, which can reduce the influence of common-mode noise on the final measurement result, making the signal output by the sensor more accurate. Moreover, the differential signals corresponding to the two induction electrode solder joints 11 are more convenient for standardized processing and calibration operations, making the entire signal processing process more standardized and efficient, reducing the cumbersome nature of having to adapt multiple different processing methods due to different numbers of solder joints, and further improving the stability and reliability of the circuit.

[0078] Further, an insulating layer is provided between the spiral coil induction electrode 1 and the top silicon layer 6. This can not only electrically isolate the spiral coil induction electrode 1 from the top silicon layer 6, avoiding short circuits between the two due to accidental contact or electric field coupling. It can also reduce signal loss and distortion during transmission, thereby improving the quality of signal transmission and further enhancing the accuracy and reliability of the sensor measurement result.

[0079] In one embodiment, the spiral coil induction electrode 1 is disposed at the center of the SOI substrate 2. Based on the basic principle of electromagnetic induction, the theoretical induction efficiency of the spiral coil induction electrode 1 is positively correlated with the coil perimeter. Disposing the spiral coil induction electrode 1 at the center of the SOI substrate 2 can ensure that the spiral coil induction electrode 1 has a large effective induction area within a limited space, so as to improve its induction efficiency and performance, and further improve the measurement accuracy and sensitivity.

[0080] Furthermore, at least two of the electrode groups are disposed around the spiral coil induction electrode 1. This setting method can not only arrange as many electrode groups as possible within a limited space to further improve the measurement accuracy and sensitivity, but also reduce the product size while ensuring the effective induction area of the spiral coil induction electrode 1, thereby realizing the reduction of the overall volume of the product.

[0081] Preferably, the proportion area of the spiral coil induction electrode 1 in the SOI substrate 2 is larger than the proportion area of the multiple electrode groups in the SOI substrate 2. Setting a larger area of the spiral coil induction electrode 1 can make the functional layout of the entire sensor more reasonable, so as to achieve more accurate and efficient measurement of the high-frequency alternating current electric field, and further improve the overall stability and reliability of the sensor.

[0082] In the specification provided here, a large number of specific details are described. However, it can be understood that the embodiments of the present invention can be practiced without these specific details. In some instances, well-known methods, structures, and technologies are not shown in detail so as not to obscure the understanding of this specification.

[0083] In addition, those of ordinary skill in the art can understand that although some embodiments described herein include certain features included in other embodiments rather than other features, the combination of the features of different embodiments means that it is within the scope of the present invention and forms different embodiments.

[0084] Those skilled in the art should understand that although the present invention has been described with reference to exemplary embodiments, various changes can be made and equivalents can be substituted for its elements without departing from the scope of the present invention. In addition, many modifications can be made to adapt a particular situation or material to the teachings of the present invention without departing from the essential scope of the present invention.

Claims

1. A field mill DC modulation and coil induction integrated MEMS electric field sensor, characterized in that Comprising: A spiral coil induction electrode, fixedly arranged on an SOI substrate, sensing the surrounding external electric field and converting the periodic change of the alternating electric field into a first signal; A comb electrode structure, fixedly arranged on the SOI substrate, comprising a piezoelectric driving structure, at least two movable shielding electrodes and at least two fixed induction electrodes. Among them, the piezoelectric driving structure is fixedly connected to the SOI substrate, receiving a periodic voltage driving signal and generating a periodic mechanical deformation; the movable shielding electrode is elastically connected to the piezoelectric driving structure and generates a periodic vertical displacement under the drive of the piezoelectric driving structure; The fixed induction electrode is correspondingly arranged with the movable shielding electrode to form an electrode group, and is fixedly connected to the SOI substrate, sensing the surrounding external electric field and converting the modulation of the low-frequency alternating current and direct current electric fields into a second signal.

2. The MEMS electric field sensor according to claim 1, characterized in that, The fixed induction electrode comprises a plurality of symmetrically distributed fixed comb tooth groups, and the comb tooth array of each fixed comb tooth group extends from the central region to the edge along the radial direction of the SOI substrate; the movable shielding electrode comprises a plurality of correspondingly arranged movable comb tooth groups, and the comb tooth array of each movable comb tooth group extends from the edge to the central region along the radial direction of the SOI substrate, forming an interleaved nested structure with the fixed comb tooth group.

3. The MEMS electric field sensor according to claim 2, wherein The voltage driving signal is composed of a forward driving voltage and a reverse driving voltage with equal magnitudes and a phase difference of 180°, which respectively act on the piezoelectric driving structures corresponding to the symmetrically distributed fixed induction electrodes.

4. The MEMS electric field sensor according to claim 1, wherein The piezoelectric driving structure is a piezoelectric cantilever beam structure, composed of an upper metal electrode, a piezoelectric material layer and a lower metal electrode.

5. The MEMS electric field sensor according to claim 4, wherein The piezoelectric material layer is made by a sol-gel film forming method, a chemical solution deposition method, a chemical vapor deposition method or a magnetron sputtering deposition method.

6. The MEMS electric field sensor according to claim 1, characterized in that, The SOI substrate comprises a top silicon layer, a buried oxide layer and a bottom silicon layer arranged in sequence from top to bottom.

7. The MEMS electric field sensor according to claim 6, wherein The spiral coil induction electrode, the piezoelectric driving structure and the fixed induction electrode are welded on the top silicon layer.

8. The MEMS electric field sensor according to claim 7, wherein An insulating layer is provided between the spiral coil induction electrode and the top silicon layer.

9. The MEMS electric field sensor according to claim 1, characterized in that, The spiral coil induction electrode is arranged at the center of the SOI substrate.

10. The MEMS electric field sensor according to claim 9, wherein, At least two of the electrode groups are arranged around the spiral coil induction electrode.

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