Z-axis Resonant Microaccelerometer with Electrostatic Stiffness Regulation Based on Tunnel Magnetoresistance Detection

Abstract

An electrostatic stiffness - adjustable Z - axis resonant micro - accelerometer based on tunneling magnetoresistance detection, comprising: a support frame, a bonding substrate, a torsional support beam, a torsional mass block, a resonant mass block, a magnetoresistive element, a fixed stiffness - adjusting electrode, a movable stiffness - adjusting electrode, a detection magnet and a driving magnet; The support frame is arranged on the bonding substrate, the torsional mass block is arranged in a first mass - block mounting groove opened on the support frame, and the torsional mass block is connected to the support frame through the torsional support beam; The resonant mass block is arranged in a second mass - block mounting groove opened on the torsional mass block, and four corners of the resonant mass block are connected to the torsional mass block through driving combined beams. The magnetoresistive element is arranged on the resonant mass block, and movable stiffness - adjusting electrodes are arranged at both ends of the X - axis of the resonant mass block; Fixed stiffness - adjusting electrodes, a detection magnet and a driving magnet are arranged on the bonding substrate, and are respectively arranged corresponding to the positions of the adjusting - electrode exposure holes, the magnetoresistive element and the driving combined beams.

Description

Technical Field

[0001] The present invention relates to an electrostatic stiffness - adjusted Z - axis resonant micro - accelerometer device based on tunnel magnetoresistance detection, belonging to the technical field of measurement instrument components for micro - inertial navigation. Background Technique

[0002] Inertial technology works in a completely autonomous manner without contacting the outside world, having the advantages of being autonomous, real - time, and interference - free. Gyroscopes are the core devices of inertial navigation technology and play a crucial role in modern aerospace, national defense, and military fields.

[0003] Accelerometers are one of the most critical components in inertial navigation systems, used to measure the acceleration value of the vehicle. Based on this, the speed and position information of the vehicle can be obtained through calculation. Both inertial navigation and guidance are based on the sensitive measurement of the vehicle's motion acceleration by accelerometers. Therefore, the performance of accelerometers directly affects the measurement accuracy and stability of the entire system and the final navigation accuracy.

[0004] Resonant micro - accelerometers measure external acceleration through the frequency change of the resonant cavity. They have advantages such as a large dynamic range, high sensitivity, and anti - interference ability. Due to the high linearity, high precision, and process characteristics compatible with traditional silicon micromachining of in - plane linear resonators, most of the currently studied resonant micro - accelerometers are used to measure in - plane acceleration. There are few out - of - plane resonant accelerometers that can measure acceleration in the vertical plane. This structure uses a magnetoresistance detection method to calculate the natural frequency of the resonant structure. In terms of the driving method, electrostatic driving has good stability, but its driving amplitude is small; electromagnetic driving has advantages such as a large driving amplitude and a simple structure. In terms of the detection method, capacitance detection uses a comb - tooth structure with a relatively high displacement resolution, but the manufacturing process accuracy requirements for comb - teeth are extremely high, and the yield is low. The tunnel magnetoresistance effect is based on the spin effect of electrons in a magnetic multi - layer film structure with a non - magnetic layer of insulator or semiconductor separating the magnetic pinned layer and the magnetic free layer. When the magnetic free layer is under the action of an external field, its magnetization direction changes, while the magnetization direction of the pinned layer remains unchanged. At this time, the relative orientation of the magnetization intensities of the two magnetic layers changes, and a large resistance change can be observed across the magnetic tunnel junction of the insulating layer. This physical effect is based on the tunneling effect of electrons in the insulating layer, so it is called the tunnel magnetoresistance effect. The tunnel magnetoresistance effect has the advantages of "high sensitivity, miniaturization, and easy detection".

[0005] The natural frequency of a single resonator is very sensitive to temperature changes, which will lead to false signal output. To solve the problem of signal detection, the inventor came up with the idea of applying the tunneling magnetoresistance effect to the accelerometer structure, using a dual-resonant mass block to eliminate the influence of factors such as temperature, using electromagnetic drive, converting the change in electrostatic stiffness into a frequency change through the movement of the torsion mass block, and using a related closed-loop detection circuit to detect the natural frequency of the resonant structure, thereby realizing acceleration detection. There are no related products in this technical field yet.

[0006] Through a search of the prior art, the "Resonant Micro Accelerometer Based on Electrostatic Stiffness" in the prior art 1 (application number: CN201220188370.9), the "Sensitive Structure and Usage Method of an Electrostatic Negative Stiffness Resonant Accelerometer" in the prior art 2 (application number: CN201811617230.7), and the "Silicon Micro Resonant Accelerometer" in the prior art 3 (application number: CN201410129567.9) were found.

[0007] The above prior arts 1, 2, and 3 all adopt the capacitance drive and capacitance detection methods. The capacitance structure is suitable for MEMS process processing, but it has the disadvantages of insufficient detection sensitivity and small output signals; adopting the comb-tooth capacitance detection method has a relatively high displacement resolution, but with further miniaturization, the comb-tooth voltage is prone to breakdown, and it will also suck and fail during lateral impact. Especially, the manufacturing process accuracy requirements of the comb teeth are extremely high, and the yield is low, which restricts the development in this direction.

[0008] Based on the above problems, the present invention proposes a resonant micro accelerometer device using electromagnetic drive and tunneling magnetoresistance detection methods. The advantage of this design is that the electromagnetic drive method has a simple structure and is convenient for driving. During detection, it is detected by a magnetoresistive element with high sensitivity characteristics, with high sensitivity, low process requirements, and easy to manufacture. Summary of the Invention

[0009] The purpose of the present invention is to design a Z-axis resonant micro accelerometer based on tunneling magnetoresistance detection for the deficiencies of the background technology, improve the detection accuracy of the accelerometer, adopt electromagnetic drive and magnetoresistance detection methods, change the electrostatic stiffness of the resonant structure by inputting acceleration, thereby causing a change in the natural frequency of the resonant structure, and realize the detection of acceleration by detecting the natural frequency of the resonant structure.

[0010] The technical solution of the present invention is as follows:

[0011] A Z-axis resonant micro accelerometer for electrostatic stiffness adjustment based on tunneling magnetoresistance detection includes: a support frame, a bonding substrate, a torsion support beam, a torsion mass block, a resonant mass block, a magnetoresistive element, a fixed stiffness adjustment electrode, a movable stiffness adjustment electrode, a detection magnet, and a drive magnet;

[0012] The support frame is disposed on the bonding substrate. A first mass block mounting groove, which is asymmetrically arranged with the Y-axis center line of the support frame as the central axis, is formed on the support frame. The torsion mass block is adapted to the shape of the first mass block mounting groove and is disposed in the first mass block mounting groove. The torsion mass block is connected to the support frame through a torsion support beam;

[0013] On the torsion mass block, two second mass block mounting grooves are symmetrically arranged with the Y-axis center line of the support frame as the central axis. Adjusting electrode exposure holes are respectively formed between and on both sides of the two second mass block mounting grooves; The resonant mass block is disposed in the second mass block mounting groove. Four corners of the resonant mass block are connected to the torsion mass block through driving combined beams. The magnetoresistive element is disposed on the resonant mass block. Movable stiffness adjusting electrodes are disposed at both ends of the X-axis of the resonant mass block;

[0014] A square groove is formed on the upper surface of the bonding substrate. A fixed stiffness adjusting electrode, a detection magnet and a driving magnet are disposed in the groove. The fixed stiffness adjusting electrode is disposed corresponding to the position of the adjusting electrode exposure hole and cross-matches with the movable stiffness adjusting electrode. The detection magnet is disposed corresponding to the position of the magnetoresistive element. The driving magnet is disposed corresponding to the position of the driving combined beam.

[0015] Optionally, it is characterized in that the torsion support beam is located on the Y-axis center line of the support frame.

[0016] Optionally, it is characterized in that a magnetic focusing unit is deposited above the detection magnet, and the shape of the magnetic focusing unit includes a triangle or a square.

[0017] Optionally, it is characterized in that both the fixed stiffness adjusting electrode and the movable stiffness adjusting electrode are comb electrodes, and the comb teeth parts of the fixed stiffness adjusting electrode and the movable stiffness adjusting electrode cross-match.

[0018] Optionally, it is characterized in that the driving combined beam includes: a first driving beam, a second driving beam and a driving beam connection block. The first driving beam and the second driving beam are respectively arranged in parallel on both sides of the driving beam connection block and are respectively connected to the driving beam connection block at one end. The other ends of the first driving beam and the second driving beam are respectively connected to the resonant mass block. The other end of the driving beam connection block is connected to the torsion mass block.

[0019] Optionally, it is characterized in that the electrostatic stiffness-adjusted Z-axis resonant micro-accelerometer based on tunnel magnetoresistance detection further includes: a driving electrode, a driving wire, a detection electrode and a detection wire;

[0020] The driving electrode and the detection electrode are disposed on the upper surface of the torsion mass block near the edge of the torsion support beam;

[0021] Both ends of the driving wire are respectively connected to the positive and negative electrodes of the driving electrode. The middle part of the driving wire is arranged on the driving combined beam. One end of the detecting wire is connected to the detecting electrode, and the other end of the detecting wire is connected to the tunneling magnetoresistance element.

[0022] The present invention provides a Z-axis resonant micro-accelerometer with electrostatic stiffness adjustment based on tunneling magnetoresistance detection, which adopts electromagnetic driving and tunneling magnetoresistance detection methods, simplifies the driving method, reduces the process difficulty, and improves the detection sensitivity at the same time. The designed Z-axis resonant micro-accelerometer can realize the conversion of the input acceleration into the change of electrostatic stiffness, thereby causing the change of the natural frequency of the resonant structure. The purpose of detecting the input acceleration is achieved by detecting the change of the natural frequency.

[0023] Moreover, the present invention adopts a double-resonant mass block. The natural frequency of a single-resonant structure is extremely sensitive to temperature changes, which will lead to false signal output. The adoption of a double-resonant mass block can eliminate the influence of factors such as temperature on its natural frequency. The present invention adopts the tunneling magnetoresistance effect with high-sensitivity characteristics for detection to improve the detection accuracy of the micro-accelerometer. The tunneling magnetoresistance element has high-sensitivity characteristics to weak magnetic field changes, and can realize more accurate measurement of the natural frequency of the resonant structure. The structure design is reasonable and easy to use. The detection of the Z-axis acceleration can be realized by detecting the change of the natural frequency of the resonant structure.

[0024] The present invention deposits a high-permeability soft magnetic material on the detection magnet, which has a magnetic focusing effect, realizes enhancing the local magnetic field intensity, thereby increasing the magnetic field change rate, and forms a stable magnetic field with a high change rate. When the magnetic field sensed by the tunneling magnetoresistance element changes, the resistance value of the tunneling magnetoresistance element will change violently under the weak magnetic field change. This change can improve the detection accuracy of the designed micro-gyro by one to two orders of magnitude. The overall structure of the present invention is reasonably designed, the interface circuit is simple, and the detection accuracy is high. Description of the Drawings

[0025] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0026] Figure 2 It is a top view of the overall structure of the present invention;

[0027] Figure 3 It is a schematic diagram of the bonding substrate structure of the present invention;

[0028] Figure 4 It is a top view of the bonding substrate structure of the present invention;

[0029] Figure 5 It is a schematic diagram of the torsion mass block structure of the present invention;

[0030] Figure 6Top view of the torsional mass block structure of the present invention;

[0031] Figure 7 Schematic diagram of the resonant mass block structure of the present invention;

[0032] Figure 8 Top view of the resonant mass block structure of the present invention;

[0033] Figure 9 Schematic diagram of the driving electrode, driving wire, detecting electrode and detecting wire structures of the present invention;

[0034] Figure 10 Top view of the driving electrode, driving wire, detecting electrode and detecting wire structures of the present invention.

[0035] As shown in the figure, the list of reference numerals is as follows:

[0036] 1 - Support frame; 2 - Torsional support beam; 3 - Torsional mass block; 4, 5 - Resonant mass blocks; 6, 8, 9 - Fixed stiffness adjustment electrodes; 7a, 7b, 7c, 7d - Movable stiffness adjustment electrodes; 10, 13 - Magnetoresistive elements; 11, 14 - Detecting wires; 12, 15 - Detecting electrodes; 16, 18, 20, 22 - Driving electrodes; 17, 19, 21, 23 - Driving wires; 24a, 24b, 24c, 24d - First driving beams; 25a, 25b, 25c, 25d - Driving beam connection blocks; 26a, 26b, 26c, 26d - Second driving beams; 27 - Bonding substrate; 28, 29 - Detecting magnets; 30, 31, 32, 33 - Driving magnets. Detailed implementation manners

[0037] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals indicate the same or similar elements or elements with the same or similar functions from beginning to end. The embodiments described below with reference to the drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation of the present invention.

[0038] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred combination or element must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention. Additionally, during the description of the embodiments of the present invention, the positional relationships of "upper", "lower", "front", "rear", "left", "right", etc. of all the devices in the drawings are all Figure 1 used as the standard.

[0039] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "connected" and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0040] The present invention will be further described below with reference to the accompanying drawings:

[0041] As Figure 1 、 2 shown, the electrostatic stiffness - adjusted Z - axis resonant micro - accelerometer based on tunneling magnetoresistance detection includes: a support frame 1, a bonding substrate 27, a torsion support beam 2, a torsion mass 3, resonant masses 4 and 5, magnetoresistive elements 10 and 13, fixed stiffness - adjusting electrodes 6, 8, 9, movable stiffness - adjusting electrodes 7a, 7b, 7c, 7d, detection magnets 28 and 29, and drive magnets 30, 31, 32, 33.

[0042] As Figure 5 、 6 shown, the support frame 1 is disposed on the bonding substrate 27. A first mass - block mounting groove is formed on the support frame 1 and is asymmetrically arranged with the Y - axis center line of the support frame 1 as the central axis. The first mass - block mounting groove includes, but is not limited to, a T - shape.

[0043] As Figure 1 、 2 、5, 6 shown, the torsion mass 3 is adapted to the shape of the first mass - block mounting groove and is disposed in the first mass - block mounting groove. There is a gap between the torsion mass 3 and the support frame 1. The shape of the torsion mass 3 includes, but is not limited to, a T - shape. The torsion mass 3 is connected to the support frame 1 through a torsion support beam 2, and the torsion support beam 2 is located on the Y - axis center line of the support frame 1.

[0044] As Figure 5 、 6 shown, two second mass - block mounting grooves are symmetrically arranged on the torsion mass 3 with the Y - axis center line of the support frame 1 as the central axis. Adjusting - electrode exposure holes are formed between the two second mass - block mounting grooves and on both sides.

[0045] As Figure 1 、 2As shown in FIGS. 7 and 8, the resonant mass blocks 4 and 5 are arranged in the second mass block mounting groove. Four corners of the resonant mass blocks 4 and 5 are connected to the torsion mass block 3 through driving combined beams. The magnetoresistive elements 10 and 13 are arranged on the resonant mass blocks 4 and 5. The movable stiffness adjusting electrodes 7a, 7b, 7c, and 7d are arranged at two ends of the resonant mass blocks 4 and 5 along the X axis.

[0046] As Figures 1-4 shown in FIGS. 7 and 8, the bonding substrate 27 has the same shape as the support frame 1 and is square as a whole, providing support for the support frame 1. A square groove is arranged on the upper surface of the bonding substrate 27. The fixed stiffness adjusting electrodes 6, 8, and 9, the detection magnets 28 and 29, and the driving magnets 30, 31, 32, and 33 are arranged in the groove. The depth of the groove is greater than the thickness of the detection magnets 28 and 29. The fixed stiffness adjusting electrodes 6, 8, and 9 are arranged corresponding to the positions of the adjusting electrode exposure holes and cross-match with the movable stiffness adjusting electrodes 7a, 7b, 7c, and 7d. The fixed stiffness adjusting electrodes 6, 8, and 9 are exposed to the same plane for matching with the movable stiffness adjusting electrodes 7a, 7b, 7c, and 7d through the adjusting electrode exposure holes. The detection magnets 28 and 29 are arranged corresponding to the positions of the magnetoresistive elements 10 and 13, and the driving magnets 30, 31, 32, and 33 are arranged corresponding to the positions of the driving combined beams. Specifically, the detection magnets 28 and 29 are located below the magnetoresistive elements 10 and 13, and the driving magnets 30, 31, 32, and 33 are located below the driving combined beams. The detection magnets 28 and 29 can be permanent magnets, energized coils, light-controlled magnets, etc., all devices that can generate a magnetic field. In this embodiment, permanent magnets are used for illustration. The detection magnets 28 and 29 are square in shape and can be obtained by process etching. A magnetic focusing unit is deposited above the detection magnets 28 and 29, and the shape of the magnetic focusing unit can be triangular, square, etc. The driving magnets 30, 31, 32, and 33 are rectangular permanent magnets.

[0047] As Figures 1-4 shown in FIGS. 7 and 8, the fixed stiffness adjusting electrodes 6, 8, and 9 and the movable stiffness adjusting electrodes 7a, 7b, 7c, and 7d are all comb electrodes. The comb teeth parts of the fixed stiffness adjusting electrodes 6, 8, and 9 and the movable stiffness adjusting electrodes 7a, 7b, 7c, and 7d cross-match.

[0048] As Figures 1-2As shown in FIGS. 7, 8, the driving combined beams are respectively arranged at the four corners of the resonant mass blocks 4 and 5. The eight driving combined beams have exactly the same structural dimensions. The driving combined beam includes: first driving beams 24a, 24b, 24c, 24d, second driving beams 26a, 26b, 26c, 26d, and driving beam connection blocks 25a, 25b, 25c, 25d. The first driving beams 24a, 24b, 24c, 24d and the second driving beams 26a, 26b, 26c, 26d are respectively arranged in parallel on both sides of the driving beam connection blocks 25a, 25b, 25c, 25d and one ends thereof are respectively connected to the driving beam connection blocks 25a, 25b, 25c, 25d. The other ends of the first driving beams 24a, 24b, 24c, 24d and the second driving beams 26a, 26b, 26c, 26d are respectively connected to the resonant mass blocks 4 and 5. The other ends of the driving beam connection blocks 25a, 25b, 25c, 25d are connected to the torsion mass block 3. The first driving beams 24a, 24b, 24c, 24d and the second driving beams 26a, 26b, 26c, 26d are of slender beam structures, that is, the length of the beam is much greater than its width. The thicknesses of the first driving beams 24a, 24b, 24c, 24d and the second driving beams 26a, 26b, 26c, 26d are the same as the thickness of the driving beam connection blocks 25a, 25b, 25c, 25d.

[0049] As shown in Figures 1-2 FIGS. 9, 10, the electrostatic stiffness-adjusting Z-axis resonant micro-accelerometer based on tunneling magnetoresistance detection further includes: driving electrodes 16, 18, 20, 22, driving wires 17, 19, 21, 23, detection electrodes 12, 15, and detection wires 11, 14.

[0050] The driving electrodes 16, 18, 20, 22 and the detection electrodes 12, 15 are arranged on the upper surface of the torsion mass block 3 near the edge of the torsion support beam 2.

[0051] As shown in Figure 9 and 10 FIGS., the two ends of the driving wires 17, 19, 21, 23 are respectively connected to the positive and negative electrodes of the driving electrodes 16, 18, 20, 22. The middle parts of the driving wires 17, 19, 21, 23 are arranged on the driving combined beams. When the driving wires are energized, they are subjected to Ampere force in the magnetic field and thus generate driving force. One end of each of the detection wires 11, 14 is connected to the detection electrodes 12, 15, and the other ends of the detection wires 11, 14 are connected to the tunneling magnetoresistance elements 10, 13.

[0052] Principle of the invention:

[0053] The electrostatic stiffness - adjusted Z - axis resonant micro - accelerometer based on tunneling magnetoresistance detection of the present invention is driven by the Ampere force received by the energized driving wire in the magnetic field. In the driving mode, the resonant mass blocks on both sides of the structure reciprocate along the Y - axis. An in - plane drive is achieved by applying an excitation to the driving electrode to make the resonant mass blocks vibrate at their natural frequencies.

[0054] After the micro - accelerometer device is driven, the resonant mass blocks on both sides reciprocate along the Y - axis direction at their natural frequencies respectively. The magnetoresistive elements arranged on the resonant mass blocks will detect the magnetic field change caused by the resonant displacement. The resonant displacement is fed back to the driving electrode through a closed - loop self - oscillation system to track the natural frequency of the resonator. A bias voltage is applied between the fixed stiffness - adjusting electrode and the movable stiffness - adjusting electrode on the resonant mass block, thereby generating an electrostatic force and an electrostatic stiffness.

[0055] When an input z - axis acceleration is applied, due to the imbalance of the anti - torsion masses on both sides of the torsion mass block, the torsion mass block will twist around the torsion support beam. This will cause the overlapping area between the fixed stiffness - adjusting electrode and the movable stiffness - adjusting electrode on the resonant mass block to change, resulting in a change in the electrostatic force and electrostatic stiffness of the resonator, and the natural frequency of the resonator will change due to the change in electrostatic stiffness. Therefore, by measuring the frequency change of the closed - loop self - oscillation system, the acceleration can be detected.

[0056] The present invention provides an electrostatic stiffness - adjusted Z - axis resonant micro - accelerometer based on tunneling magnetoresistance detection, which adopts an electromagnetic drive and a tunneling magnetoresistance detection method. It simplifies the drive method, reduces the process difficulty, and improves the detection sensitivity at the same time. The designed Z - axis resonant micro - accelerometer can realize the conversion of the input acceleration into a change in electrostatic stiffness, which in turn causes a change in the natural frequency of the resonant structure. The input acceleration is detected by detecting the change in the natural frequency.

[0057] Moreover, the present invention adopts a double - resonant mass block. The natural frequency of a single - resonant structure is extremely sensitive to temperature changes, which will lead to false signal output. Using a double - resonant mass block can eliminate the influence of factors such as temperature on its natural frequency. The present invention uses the tunneling magnetoresistance effect with high - sensitivity characteristics for detection to improve the detection accuracy of the micro - accelerometer. The magnetoresistive element has high - sensitivity characteristics to weak magnetic field changes, and can achieve more accurate measurement of the natural frequency of the resonant structure. The structure design is reasonable and easy to use. The detection of the Z - axis acceleration can be realized by detecting the change in the natural frequency of the resonant structure.

[0058] In the present invention, a high-permeability soft magnetic material is deposited on a detection magnet, which has a magnetic focusing effect, realizes enhancing the local magnetic field intensity so as to increase the magnetic field change rate, forms a stable magnetic field with a high change rate. When the magnetic field sensed by the tunneling magnetoresistance element changes, the resistance value of the tunneling magnetoresistance element will change violently under a weak magnetic field change. This change can improve the detection accuracy of the designed micro gyro by one to two orders of magnitude. The overall structure of the present invention is reasonably designed, the interface circuit is simple, and the detection accuracy is high.

[0059] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0060] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. An electrostatic stiffness - adjusted Z - axis resonant micro - accelerometer based on tunneling magnetoresistance detection, characterized in that, Comprising: A support frame (1), a bonding substrate (27), a torsion support beam (2), a torsion mass (3), resonant masses (4, 5), magnetoresistive elements (10, 13), fixed stiffness adjustment electrodes (6, 8, 9), movable stiffness adjustment electrodes (7a, 7b, 7c, 7d), detection magnets (28, 29), and drive magnets (30, 31, 32, 33); The support frame (1) is disposed on the bonding substrate (27). A first mass mounting groove that is asymmetrically disposed about the Y-axis center line of the support frame (1) is formed on the support frame (1). The torsion mass (3) is disposed in the first mass mounting groove in a shape adapted to the first mass mounting groove, and the torsion mass (3) is connected to the support frame (1) through the torsion support beam (2); Two second mass mounting grooves are symmetrically disposed about the Y-axis center line of the support frame (1) on the torsion mass (3). Adjustment electrode exposure holes are formed between and on both sides of the two second mass mounting grooves. The resonant masses (4, 5) are disposed in the second mass mounting grooves. Four corners of the resonant masses (4, 5) are connected to the torsion mass (3) through drive combined beams. The magnetoresistive elements (10, 13) are disposed on the resonant masses (4, 5). The movable stiffness adjustment electrodes (7a, 7b, 7c, 7d) are disposed at both ends of the X-axis of the resonant masses (4, 5); A square groove is formed on the upper surface of the bonding substrate (27). The fixed stiffness adjustment electrodes (6, 8, 9), the detection magnets (28, 29), and the drive magnets (30, 31, 32, 33) are disposed in the groove. The fixed stiffness adjustment electrodes (6, 8, 9) are disposed at positions corresponding to the adjustment electrode exposure holes and cross-match with the movable stiffness adjustment electrodes (7a, 7b, 7c, 7d). The detection magnets (28, 29) are disposed at positions corresponding to the magnetoresistive elements (10, 13). The drive magnets (30, 31, 32, 33) are disposed at positions corresponding to the drive combined beams.

2. The electrostatic stiffness - adjusted Z - axis resonant micro - accelerometer based on tunneling magnetoresistance detection according to claim 1, characterized in that, The torsion support beam (2) is located on the Y-axis center line of the support frame (1).

3. The electrostatic stiffness - adjusted Z - axis resonant micro - accelerometer based on tunneling magnetoresistance detection according to claim 1, characterized in that, A magnetic focusing unit is deposited above the detection magnets (28, 29), and the shape of the magnetic focusing unit includes a triangle or a square.

4. The electrostatic stiffness - adjusted Z - axis resonant micro - accelerometer based on tunneling magnetoresistance detection according to claim 1, characterized in that, Both the fixed stiffness adjustment electrodes (6, 8, 9) and the movable stiffness adjustment electrodes (7a, 7b, 7c, 7d) are comb electrodes, and the comb teeth portions of the fixed stiffness adjustment electrodes (6, 8, 9) and the movable stiffness adjustment electrodes (7a, 7b, 7c, 7d) cross-match.

5. The electrostatic stiffness - adjusted Z - axis resonant micro - accelerometer based on tunneling magnetoresistance detection according to claim 1, characterized in that, The driving combined beam includes: first driving beams (24a, 24b, 24c, 24d), second driving beams (26a, 26b, 26c, 26d), and driving beam connection blocks (25a, 25b, 25c, 25d). The first driving beams (24a, 24b, 24c, 24d) and the second driving beams (26a, 26b, 26c, 26d) are respectively arranged in parallel on both sides of the driving beam connection blocks (25a, 25b, 25c, 25d), and one ends of them are respectively connected to the driving beam connection blocks (25a, 25b, 25c, 25d). The other ends of the first driving beams (24a, 24b, 24c, 24d) and the second driving beams (26a, 26b, 26c, 26d) are respectively connected to the resonant mass blocks (4, 5), and the other ends of the driving beam connection blocks (25a, 25b, 25c, 25d) are connected to the torsion mass block (3).

6. The electrostatic stiffness - adjusted Z - axis resonant micro - accelerometer based on tunneling magnetoresistance detection according to claim 1, characterized in that, The electrostatic stiffness - adjustable Z - axis resonant micro - accelerometer based on tunneling magnetoresistance detection further includes: driving electrodes (16, 18, 20, 22), driving wires (17, 19, 21, 23), detection electrodes (12, 15), and detection wires (11, 14); The driving electrodes (16, 18, 20, 22) and the detection electrodes (12, 15) are arranged on the upper surface of the torsion mass block (3) near the edge of the torsion support beam (2); Both ends of the driving wires (17, 19, 21, 23) are respectively connected to the positive and negative electrodes of the driving electrodes (16, 18, 20, 22). The middle parts of the driving wires (17, 19, 21, 23) are arranged on the driving combined beam. One end of each of the detection wires (11, 14) is connected to the detection electrodes (12, 15), and the other ends of the detection wires (11, 14) are connected to the tunneling magnetoresistance elements (10, 13).

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