Biaxial silicon micro-accelerometer based on three-degree-of-freedom weak coupling resonator

Abstract

The invention discloses a biaxial silicon micro-accelerometer based on a three-degree-of-freedom weak coupling resonator, and belongs to the technical field of micro-electro-mechanical systems and microfluid measurement. Comprising a glass base and a silicon micromechanical sensor, the center of the glass base is provided with a protruding common anchor point, the silicon micromechanical sensor is connected to the glass base through the common anchor point, and signal electrodes for transmitting signals are distributed on the glass base; the silicon micromechanical sensor comprises a stress base and resonance modules; the stress base is mounted on the glass base, and the resonance modules arranged in a Y shape are arranged on the stress base; the Y-shaped head of the resonance module is provided with a pair of resonators which are perpendicular to each other and are used for detecting acceleration in the horizontal direction and acceleration in the vertical direction respectively. The stability and the measurement accuracy of the biaxial accelerometer are further improved by arranging a resonator arrangement mode of a stable structure and cooperating with the mechanical stable design of the amplification unit and the safety structure.

Description

Technical Field

[0001] The invention relates to a silicon micro-accelerometer, in particular to a dual-axis silicon micro-accelerometer based on a three-degree-of-freedom weakly coupled resonator, and belongs to the technical field of micro-electromechanical systems and microfluid measurement. Background Art

[0002] Micro-electromechanical system (MEMS) is a tiny device that combines mechanical, electronic and computer technologies. It has the advantages of small size, light weight, low power consumption and low cost, and has been widely used in many fields. MEMS sensors are sensors manufactured based on MEMS processing technology, usually based on capacitive, piezoresistive, piezoelectric, photoelectric and resonant mechanisms.

[0003] In recent years, the weak coupling resonant sensing mechanism has begun to attract widespread attention due to its unique advantages. Compared with the traditional resonant sensing mechanism based on frequency output, the weak coupling resonant sensing mechanism converts the measured change into the change of the amplitude ratio of the weak coupling resonant system. It has the advantages of high relative sensitivity and good temperature stability, and is expected to be widely used in MEMS sensors.

[0004] In recent years, research institutions at home and abroad have begun to conduct some research on weakly coupled resonant sensors. The existing weakly coupled resonator stiffness sensors have been proven through comparative experiments that the higher the number of degrees of freedom of the coupled sensor, the higher the sensitivity increase based on the amplitude ratio output. Although weakly coupled resonators perform well in many applications, there is still the problem of inaccurate measurements in interference environments, and the poor stability of the mechanical structure of existing resonators can easily lead to measurement errors due to external interference. Summary of the invention

[0005] The technical purpose to be achieved by the present invention is to improve the stability and measurement accuracy of the dual-axis accelerometer by setting a resonator arrangement with a stable structure and coordinating the mechanical stability design of the amplification unit and the safety structure.

[0006] In order to achieve the above technical objectives, the present invention provides the following technical solutions: including a glass base and a silicon micromechanical sensor, wherein a raised common anchor point is arranged at the exact center of the glass base, and the silicon micromechanical sensor is connected to the glass base via the common anchor point. The common anchor point not only ensures that the sensor is subjected to uniform force during operation and reduces structural deviation caused by vibration or external impact, but also ensures that the signal electrodes are evenly distributed on the glass base, thereby achieving stable and rapid signal transmission; the glass base is covered with signal electrodes for transmitting signals.

[0007] Preferably, the silicon micromachined sensor includes a force-bearing base and a resonant module. The force-bearing base is mounted on the glass base, and the resonant module arranged in a "Y" shape is disposed thereon. The "Y" structure has a pair of perpendicular resonators on the base, which are respectively used to detect accelerations in the horizontal and vertical directions; a pair of perpendicular resonators are provided at the "Y" head of the resonant module, which are respectively used to detect accelerations in the horizontal and vertical directions.

[0008] Preferably, the resonant module includes a first resonator, a second resonator, and a third resonator. The first resonator and the second resonator are distributed at 90°, so that a coupling relationship is formed between the resonators. The signals are commonly referenced and complemented through a common anchor point, so that when the system is affected by an external acceleration, differential responses can be generated between different resonators, thereby improving the detection sensitivity to small displacement changes and helping to suppress environmental interference and system noise.

[0009] Further, the inner ends of both are connected to the third resonator through the common anchor point. The angles between the third resonator and the first resonator and the second resonator are respectively arranged at 135°; this angle setting not only makes the coupling effect more significant, but also enables more reasonable mechanical transmission and distribution, thereby improving the overall stability and measurement accuracy of the system.

[0010] Preferably, an amplification unit is connected to the outer ends of the first resonator and the second resonator.

[0011] The introduction of the amplification unit reduces the dependence on a high driving voltage, realizes low-power operation, and can maintain the advantages of high sensitivity and low noise in portable devices or long-term monitoring scenarios.

[0012] Preferably, the first resonator, the second resonator, and the third resonator have the same structure. The first resonator is composed of a first single-ended fixed resonant beam, a plurality of driving signal application structures, and a plurality of signal detection structures.

[0013] Among them, the driving signal application structures of the first resonator are symmetrically arranged inside the comb teeth of the first single-ended fixed resonant beam, and are inserted into the comb teeth of the first single-ended fixed resonant beam to form a driving capacitor plate group; the signal detection structures are symmetrically distributed outside the comb teeth of the first single-ended fixed resonant beam, and are inserted into the comb teeth of the first single-ended fixed resonant beam to form a detection capacitor plate group.

[0014] The capacitive comb-drive and detection structure, by combining high-sensitivity amplitude ratio signal extraction, reduces the driving voltage requirement, achieves low-power operation, and is suitable for portable devices or long-term monitoring scenarios. The present invention utilizes the capacitance effect to achieve a uniform electric field distribution through the interleaved arrangement of electrodes, enabling the driving signal to be accurately and efficiently applied to the resonant beam, thereby causing the desired mechanical vibration.

[0015] Symmetrically distributed outside the comb teeth of the fixed resonant beam, they are inserted into the comb teeth to form a detection capacitor plate group. Through this structural design, the tiny capacitance changes generated due to the vibration of the resonant beam can be sensitively captured, and then precise detection can be achieved by using the high-sensitivity amplitude ratio signal extraction technology.

[0016] Wherein, the outer end of the third resonator is connected with a third resonator anchor for connecting the outer end of the doubly-clamped resonant beam in the third resonator, and the inner end of the doubly-clamped resonant beam is connected to the common anchor.

[0017] Wherein, the inner ends of the first resonator and the second resonator are respectively provided with a first coupling trapezoidal beam and a second coupling trapezoidal beam for coupling and connecting the third resonator.

[0018] Further, the two ends of the first coupling trapezoidal beam are respectively connected to the first singly-clamped resonant beam of the first resonator and the doubly-clamped resonant beam of the third resonator, and the second coupling trapezoidal beam is respectively connected to the second singly-clamped resonant beam of the second resonator and the doubly-clamped resonant beam of the third resonator.

[0019] Preferably, the amplification unit includes a vertical force amplification unit and a horizontal force amplification unit, which have the same structure and are symmetrically connected to the outer ends of the first resonator and the second resonator respectively, and the vertical force amplification unit and the horizontal force amplification unit are arranged perpendicular to the first resonator and the second resonator respectively.

[0020] Preferably, both the vertical force amplification unit and the horizontal force amplification unit include a support anchor, an output straight beam, a lever, and an input straight beam; the support anchor is connected to the lever, the output straight beam is connected to one end of the lever close to the support anchor, and the input straight beam is connected to the other end of the lever far from the support anchor.

[0021] Preferably, the force-bearing base is rectangular and safety structures are provided at its four corners. The safety structures include fixed anchors and folding beams, and at least a pair of mutually perpendicular folding beams are connected to the inside of the fixed anchors.

[0022] Preferably, the signal electrode includes a common electrode, a driving signal electrode, and a detection signal electrode; the common electrode is connected to one lead-out electrode; a plurality of the driving signal electrodes and a plurality of the detection signal electrodes are respectively connected to a plurality of lead-out electrodes in sequence.

[0023] The beneficial effects of the present invention are as follows: 1. Through the design of orthogonally distributed resonators and force amplification units, the present invention can accurately measure vertical and horizontal biaxial accelerations simultaneously, broaden the application scenarios, and is suitable for multi-dimensional inertial force detection in complex motion environments. At the same time, through the differential measurement of the amplitude ratios of three groups, system noise is effectively suppressed. Combining with the amplitude-sensitive characteristics of weakly coupled resonators, sub-micron displacement resolution is achieved, and the detection ability of weak acceleration signals is improved.

[0024] 2. Through the design of four groups of symmetrically arranged safety structures and their folded beams, the present invention significantly improves the mechanical reliability of the sensor under impact or overload conditions, making the resonator structure have excellent anti-overload performance, thereby avoiding the fracture or permanent deformation of the resonant beam and extending the service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are 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.

[0026] Now the above and other aspects of the present invention will be described by way of example only with reference to the drawings, where: Figure 1 is a schematic diagram of the overall mechanical structure of the present invention; Figure 2 is a schematic diagram of the silicon micromachined structure of the present invention; Figure 3 is a schematic diagram of the first, second, and third resonators of the present invention; Figure 4 is a schematic diagram of the amplification unit of the present invention; Figure 5 is a schematic diagram of the safety structure of the present invention; Figure 6 is a schematic diagram of the glass base and signal leads of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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 some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and illustrated herein can be arranged and designed in various different configurations.

[0028] Accordingly, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0029] It should be noted that like reference numerals and letters denote like items in the following drawings. Therefore, once an item is defined in one drawing, it does not require further definition and explanation in subsequent drawings.

[0030] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed during use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to 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. In addition, the terms "first", "second", "third", etc. are only used for descriptive distinction and should not be construed as indicating or implying relative importance.

[0031] Furthermore, the terms "horizontal", "vertical", "overhanging", etc. do not mean that the components are required to be absolutely horizontal or overhanging, but may be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but may be slightly inclined.

[0032] In the description of the present invention, it should also be noted that unless otherwise clearly specified and limited, the terms "set", "installed", "connected", "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 elements. 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 situations.

[0033] The following will describe in detail some embodiments of the present invention with reference to the accompanying drawings. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0034] Such as Figure 1As shown in the figure, this embodiment provides a biaxial silicon micro-accelerometer based on a three-degree-of-freedom weakly coupled resonator. The upper silicon micro-sensor serves as a signal-sensitive mechanism for signal conversion and is fabricated using silicon microfabrication technology. The lower layer is a glass base 7 serving as a signal output layer, which is fabricated through glass wet etching and metal layer sputtering technologies. The upper silicon micro-sensor is connected to the lower glass base 7 through anchor points, and signal electrodes are arranged on the glass base 7.

[0035] As Figure 2 shown in the figure, the upper silicon micro-sensor consists of a force-bearing base 1, a first resonator 2-1, a second resonator 2-2, a third resonator 2-3, a vertical force amplification unit 3-1, a horizontal force amplification unit 3-2, first, second, third, and fourth safety structures 4-1, 4-2, 4-3, 4-4, and first and second coupled trapezoidal beams 5-1, 5-2; wherein the first resonator 2-1 and the second resonator 2-2 are respectively located in the upper and right directions of the force-bearing base 1, with an included angle of 90° distribution. The third resonator 2-3 is located in the lower left of the force-bearing base 1 and is respectively distributed at an included angle of 135° with the first and second resonators 2-1, 2-2. One end of the three resonators is respectively connected by a common anchor point 2-4.

[0036] In this embodiment, the vertical force amplification unit 3-1 and the horizontal force amplification unit 3-2 are respectively located at the upper and right positions of the force-bearing base 1. Among them, the vertical force amplification unit 3-1 is located on the upper side of the force-bearing base 1, and the horizontal force amplification unit 3-2 is located on the right side of the force-bearing base 1.

[0037] In this embodiment, the first, second, third, and fourth safety structures 4-1, 4-2, 4-3, 4-4 are respectively symmetrically arranged on the upper left, lower left, upper right, and lower right sides of the force-bearing base 1; a vertical force output straight beam 3-1-4 is provided on the vertical force amplification unit 3-1; a horizontal force output straight beam (3-2-4) is provided on the horizontal force amplification unit 3-2; the first resonator 2-1 is connected to the vertical force output straight beam 3-1-4 on the vertical force amplification junction 3-1, and the second resonator 2-2 is connected to the horizontal force output straight beam 3-2-4 on the horizontal force amplification unit 3-2; a vertical force input straight beam 3-1-2 is provided on the vertical force amplification unit 3-1, and a horizontal force input straight beam 3-2-2 is provided on the horizontal force amplification unit 3-2, and they are respectively connected to the force-bearing base 1 on the upper side and the right side of the force-bearing base 1.

[0038] In this embodiment, the two folding beams 4-1-2, 4-1-3 on the first safety structure 4-1, the two folding beams 4-2-2, 4-2-3 on the second safety structure 4-2, the two folding beams 4-3-2, 4-3-3 on the third safety structure 4-3, and the two folding beams 4-4-2, 4-4-3 on the fourth safety structure 4-4 are all connected to the force-bearing base 1.

[0039] In this embodiment, two ends of the first coupling trapezoidal beam 5-1 are respectively connected to the first single-ended fixed resonant beam 2-1-1 of the first resonator 2-1 and the double-ended fixed resonant beam 2-3-1 of the third resonator 2-3, and the second coupling trapezoidal beam 5-2 is respectively connected to the second single-ended fixed resonant beam 2-2-1 of the second resonator 2-2 and the double-ended fixed resonant beam 2-3-1 of the third resonator 2-3.

[0040] As Figure 3 shown, the structures of the first resonator 2-1 and the second resonator 2-2 are exactly the same. The first resonator 2-1 is composed of a first single-ended fixed resonant beam 2-1-1, first, second, third, and fourth drive signal application structures 2-1-2, 2-1-3, 2-1-4, 2-1-5, and first and second signal detection structures 2-1-6, 2-1-7.

[0041] In this embodiment, the four drive signal application structures 2-1-2, 2-1-3, 2-1-4, 2-1-5 of the first resonator 2-1 are symmetrically arranged inside the comb teeth of the first single-ended fixed resonant beam 2-1-1 and are inserted into the comb teeth of the first single-ended fixed resonant beam 2-1-1 to form a drive capacitor plate group; the two signal detection structures 2-1-6, 2-1-7 are symmetrically distributed outside the comb teeth of the first single-ended fixed resonant beam 2-1-1 and are inserted into the comb teeth of the first single-ended fixed resonant beam 2-1-1 to form a detection capacitor plate group.

[0042] It should be noted that since the structures of the first resonator 2-1 and the second resonator 2-2 in this embodiment are the same, the reference numerals 2-2-2 to 2-2-7 in the drawings Figure 3 correspond to 2-1-1 to 2-1-7 in the first resonator 2-1.

[0043] In this embodiment, the third resonator 2-3 is composed of a third resonator anchor 2-3-8, a double-ended fixed resonant beam 2-3-1, first, second, third, and fourth drive signal application structures 2-3-2, 2-3-3, 2-3-4, 2-3-5, and first and second signal detection structures 2-3-6, 2-3-7; the four drive signal application structures 2-3-2, 2-3-3, 2-3-4, 2-3-5 of the third resonator 2-3 are symmetrically arranged inside the comb teeth of the double-ended fixed resonant beam 2-3-1 and are inserted into the comb teeth of the double-ended fixed resonant beam 2-3-1 to form a drive capacitor plate group; the two signal detection structures 2-3-6, 2-3-7 are symmetrically distributed outside the comb teeth of the double-ended fixed resonant beam 2-3-1 and are inserted into the comb teeth of the double-ended fixed resonant beam 2-3-1 to form a detection capacitor plate group.

[0044] As Figure 4 and 5As shown, the vertical force amplification unit 3-1 and the horizontal force amplification unit 3-2 have exactly the same structure; the vertical force amplification unit 3-1 consists of a first support anchor 3-1-1, a first vertical force output straight beam 3-1-2, a first lever 3-1-3, and a first vertical force input straight beam 3-1-4; the first support anchor 3-1-1 is connected to the first lever 3-1-3, the first vertical force output straight beam 3-1-2 is connected to one end of the first lever 3-1-3 close to the first support anchor 3-1-1, and the first vertical force input straight beam 3-1-4 is connected to the other end of the first lever 3-1-3 far from the first support anchor 3-1-1.

[0045] As Figure 6 shown, the first, second, third, and fourth safety structures 4-1, 4-2, 4-3, and 4-4 have exactly the same structure; the first safety structure 4-1 consists of a first fixed anchor 4-1-1 and two folding beams 4-1-2 and 4-1-3; the first fixed anchor 4-1-1 is connected to the two folding beams 4-1-2 and 4-1-3 at 90° in the same plane respectively.

[0046] The glass base and signal leads in this embodiment are as Figure 6 shown, the signal electrodes include a common electrode 6-7-1 and a common electrode lead-out electrode 6-8-1; the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, and twelfth drive signal electrodes 6-4-1, 6-4-2, 6-4-3, 6-4-4, 6-5-1, 6-5-2, 6-5-3, 6-5-4, 6-6-1, 6-6-2, 6-6-3, 6-6-4; the first, second, third, fourth, fifth, and sixth detection signal electrodes 6-5-5, 6-5-6, 6-6-5, 6-6-6, 6-7-5, 6-7-6; the first, second, third, fourth, fifth, and sixth drive signal lead-out electrodes 6-1-1, 6-1-2, 6-2-1, 6-2-2, 6-3-1, 6-3-2; the first, second, third, fourth, fifth, and sixth detection signal lead-out electrodes 6-1-3, 6-1-4, 6-2-3, 6-2-4, 6-3-3, 6-3-4; In actual operation of this embodiment: when the force-receiving base of the sensor is subjected to an external vertical force (horizontal force), a force will be generated at the input end of the vertical force (horizontal force) input straight beam of the vertical force (horizontal force) amplification unit. After the action of the force amplification unit, the amplified force acts on the single-ended fixed resonant beam of the first (second) resonator, thereby causing a change in the stiffness of the first (second) single-ended fixed resonant beam. Since the first and second single-ended fixed resonant beams are respectively connected to the double-ended fixed resonant beam of the third resonator through the first and second coupling trapezoidal beams, the stiffness of the double-ended fixed resonant beam will also be changed accordingly. Finally, the change in the amplitude ratios of the first and second resonators, the first and third resonators, and the second and third resonators is caused. By measuring the three groups of amplitude ratios, the acceleration magnitude of the external inertial force received by the force-receiving base can be deduced inversely.

[0047] In the case of neglecting the system damping, according to its simplified mechanical dynamics model and Newton's law, the following simplified motion equation of the mass block of the resonant unit can be established: (1)

[0048] In the formula, 、 、 、 respectively represent the equivalent mass, equivalent stiffness, motion displacement, and exciting force of the mass block of the resonant unit, represents the coupling stiffness between the resonant units. The above equation can be simplified into matrix form: (2)

[0049] Among them, 、 、 、 respectively represent the mass matrix, stiffness matrix, exciting force matrix, and displacement matrix of the resonant system, and there are: (3)

[0050] (4)

[0051] (5)

[0052] (6)

[0053] In the case of free vibration, the mass blocks of all resonant units perform simple harmonic motion, and the equation has the following specific form of solution: (7)

[0054] Among them, and respectively represent the The natural frequency and phase of the displacement array of the amplitude vector of the and can be expressed as: (8)

[0055] Substituting formula (7) into (2) gives: (9)

[0056] For the vibration system, the amplitudes are not all zero, so there is: (10)

[0057] The above equation is the characteristic equation of the system. By solving the characteristic equation, the eigenvalues of the system, i.e., the values of the natural frequencies can be obtained. Then, substituting into equation (9), the eigenvector corresponding to can be obtained, which is the th natural vibration mode.

[0058] As can be seen from the above derivation, the eigenvalues and eigenvectors of the weakly coupled resonant system are both related to the parameters of the mass matrix and the stiffness matrix. Therefore, on the premise that the equivalent mass parameters of the resonant unit are known, by applying different excitation forces, the th eigenvalues or th eigenvectors of the weakly coupled resonant system can be measured.

[0059] Descriptions herein are provided to enable a person of ordinary skill in the art to make or use the present disclosure. For a person of ordinary skill in the art, various modifications to the present disclosure will be apparent, and the general principles defined herein can be applied to other variations without departing from the scope of the present disclosure. Therefore, the present disclosure is not limited to the examples and designs described herein, but should be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0060] Although one or more exemplary embodiments of the present disclosure have been described with reference to the accompanying drawings, those of ordinary skill in the art will understand that various changes in form and detail may be made therein without departing from the spirit and scope of the present disclosure as defined by the appended claims.

[0061] ​​The foregoing are only modifications that can be made to the present invention in view of the above detailed description. The terms used in the appended claims should not be construed as limiting the invention to the specific embodiments disclosed in the specification. Rather, the scope of the present invention will be determined entirely by the appended claims, which will be interpreted in accordance with established principles of claim interpretation.

Claims

1. A biaxial silicon micro-accelerometer based on a three-degree-of-freedom weakly coupled resonator, characterized in that: It includes a glass base and a silicon micromachined sensor. A raised common anchor point is provided at the exact center of the glass base. The silicon micromachined sensor is connected to the glass base through the common anchor point. The glass base is covered with signal electrodes for transmitting signals. The silicon micromachined sensor includes a force-bearing base and a resonant module. The force-bearing base is mounted on the glass base and the resonant module arranged in a "Y" shape is disposed thereon. A pair of mutually perpendicular resonators are provided at the "Y" head of the resonant module, which are respectively used to detect accelerations in the horizontal and vertical directions.

2. The biaxial silicon micro-accelerometer based on a three-degree-of-freedom weakly coupled resonator according to claim 1, characterized in that: The resonant module includes a first resonator, a second resonator, and a third resonator. The first resonator and the second resonator are distributed at 90°. The inner ends of both are connected to the third resonator through the common anchor point. The included angles between the third resonator and the first resonator, and the second resonator are respectively arranged at 135°. Amplifying units are connected to the outer ends of the first resonator and the second resonator.

3. The biaxial silicon micro-accelerometer based on a three-degree-of-freedom weakly coupled resonator according to claim 2, wherein: The first resonator, the second resonator, and the third resonator have the same structure. The first resonator is composed of a first single-ended fixed resonant beam, a plurality of drive signal application structures, and a plurality of signal detection structures. The drive signal application structures of the first resonator are symmetrically arranged inside the comb teeth of the first single-ended fixed resonant beam, and are inserted opposite to the comb teeth of the first single-ended fixed resonant beam to form a drive capacitor plate group. The signal detection structures are symmetrically distributed outside the comb teeth of the first single-ended fixed resonant beam, and are inserted opposite to the comb teeth of the first single-ended fixed resonant beam to form a detection capacitor plate group. A third resonator anchor point is connected to the outer end of the third resonator, which is used to connect the outer end of the double-ended fixed resonant beam in the third resonator. The inner end of the double-ended fixed resonant beam is connected to the common anchor point.

4. The biaxial silicon micro-accelerometer based on a three-degree-of-freedom weakly coupled resonator according to claim 3, characterized in that: First coupling trapezoidal beams and second coupling trapezoidal beams are respectively provided at the inner ends of the first resonator and the second resonator for coupling and connecting the third resonator. Both ends of the first coupling trapezoidal beam are respectively connected to the first single-ended fixed resonant beam of the first resonator and the double-ended fixed resonant beam of the third resonator. The second coupling trapezoidal beam is respectively connected to the second single-ended fixed resonant beam of the second resonator and the double-ended fixed resonant beam of the third resonator.

5. The biaxial silicon micro-accelerometer based on a three-degree-of-freedom weakly coupled resonator according to any one of claims 2-4, characterized in that: The amplifying unit includes a vertical force amplifying unit and a horizontal force amplifying unit. Both have the same structure and are symmetrically connected to the outer ends of the first resonator and the second resonator respectively. The vertical force amplifying unit and the horizontal force amplifying unit are respectively arranged perpendicular to the first resonator and the second resonator.

6. The biaxial silicon micro-accelerometer based on a three-degree-of-freedom weakly coupled resonator according to claim 5, wherein: Both the vertical force amplifying unit and the horizontal force amplifying unit include a support anchor point, an output straight beam, a lever, and an input straight beam. The support anchor point is connected to the lever. The output straight beam is connected to one end of the lever close to the support anchor point. The input straight beam is connected to the end of the lever far from the support anchor point.

7. The two-axis silicon micro-accelerometer based on a three-degree-of-freedom weakly coupled resonator according to claim 1 or 2, characterized in that: The force-bearing base is rectangular and safety structures are provided at its four corners. The safety structure includes a fixed anchor point and a folding beam. At least a pair of mutually perpendicular folding beams are connected to the inside of the fixed anchor point.

8. The biaxial silicon micro-accelerometer based on a three-degree-of-freedom weakly coupled resonator according to claim 1, wherein: The signal electrodes include a common electrode, a drive signal electrode, and a detection signal electrode. The common electrode is connected to an extraction electrode; a plurality of the drive signal electrodes and a plurality of the detection signal electrodes are respectively and sequentially connected to a plurality of extraction electrodes.

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