Three-axis MEMS inertial sensor

Abstract

A triaxial MEMS inertial sensor provided by the present invention comprises a substrate, a first mass block, a second mass block, an X-axis detection capacitor assembly, a Y-axis detection capacitor assembly and a Z-axis detection capacitor assembly, the first mass block and the second mass block are supported on the substrate through a support beam, the X-axis detection capacitor assembly is embedded in the first mass block through a second vibration elastic member, and the Y-axis detection capacitor assembly is embedded in the Z-axis detection capacitor assembly through a second vibration elastic member. The Y-axis detection capacitor assembly comprises a Y-axis detection frame and at least two Y-axis detection polar plates, the Y-axis detection frame is nested in the second mass block, the Y-axis detection polar plates are connected to the substrate, the projection part of the Y-axis detection frame on the substrate covers the Y-axis detection polar plates, and the Z-axis detection capacitor assembly is arranged on the substrate corresponding to the first mass block and the second mass block. The three capacitance detection structures are arranged on the same substrate, motion detection in the X-axis direction, the Y-axis direction and the Z-axis direction is achieved, detection in all the directions does not interfere with one another, the device size is reduced, and the detection precision in all the axial directions is improved.

Description

Technical Field

[0001] This invention belongs to the field of inertial sensor technology, specifically relating to a triaxial MEMS inertial sensor. Background Technology

[0002] Inertial sensors include accelerometers, gyroscopes, and their single, dual, and three-axis combinations. Accelerometers are used to detect the acceleration signals of an object on three independent axes of the carrier coordinate system, while gyroscopes are used to detect the angular velocity signals of the carrier relative to the navigation coordinate system. By measuring the angular velocity and acceleration of the object in three-dimensional space, the attitude of the object can be accurately characterized, which has important application value in navigation.

[0003] Existing triaxial MEMS sensors are mostly composed of three discrete single-axis sensors combined separately. However, the overall area of ​​the discretely combined triaxial MEMS sensor is large, the space utilization is not high, which is not conducive to cost saving and miniaturization of the integrated system. Furthermore, there are process deviations between the discretely combined triaxial MEMS sensors, and it is difficult to guarantee the performance consistency between the three independent axes. Summary of the Invention

[0004] The purpose of this invention is to provide a triaxial MEMS inertial sensor that can at least solve some of the defects existing in the prior art.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A triaxial MEMS inertial sensor includes a substrate, a first mass block, a second mass block, an X-axis sensing capacitor assembly, a Y-axis sensing capacitor assembly, and a Z-axis sensing capacitor assembly. The first and second mass blocks are supported on the substrate by a support beam, and a first vibration elastic element connects the first and second mass blocks. The X-axis sensing capacitor assembly is nested inside the first mass block via a second vibration elastic element. The Y-axis sensing capacitor assembly includes a Y-axis sensing frame and at least two Y-axis sensing plates. The Y-axis sensing frame is nested inside the second mass block, and the Y-axis sensing plates are connected to the substrate. The projection portion of the Y-axis sensing frame on the substrate covers the Y-axis sensing plates. The Z-axis sensing capacitor assembly is disposed on the substrate corresponding to the first and second mass blocks.

[0007] Furthermore, when the second mass block vibrates along the Y-axis, the overlapping area of ​​at least one of the Y-axis detection plates with the Y-axis detection frame increases, while the overlapping area of ​​at least one of the Y-axis detection plates with the Y-axis detection frame decreases.

[0008] Furthermore, there are two Y-axis detection plates, which are arranged in a parallel and staggered manner in the X-axis direction.

[0009] Furthermore, the second mass block has a through hole that extends through the second mass block along the Z-axis direction. The Y-axis detection frame is located inside the through hole, and both ends of the Y-axis detection frame are connected to the second mass block along the X-axis direction.

[0010] Furthermore, when the triaxial MEMS inertial sensor vibrates along the Z-axis, the distance between each Y-axis detection electrode and the Y-axis detection frame changes by the same amount.

[0011] Furthermore, the X-axis detection capacitor assembly includes an X-axis detection frame and at least two sets of X-axis detection movable comb teeth and at least two sets of X-axis detection fixed comb teeth disposed within the X-axis detection frame. The X-axis detection frame is connected to the first mass block via a second vibration elastic element. The X-axis detection movable comb teeth are connected to the X-axis detection frame, and the X-axis detection fixed comb teeth are fixed to the base via anchor points. When the first mass block vibrates along the X-axis, the capacitance value between at least one set of X-axis detection fixed comb teeth and the corresponding X-axis detection movable comb teeth increases, while the capacitance value between at least one set of X-axis detection fixed comb teeth and the corresponding X-axis detection movable comb teeth decreases.

[0012] Furthermore, the Z-axis detection capacitor assembly includes at least one first electrode plate and at least one second electrode plate disposed on the substrate, with each first electrode plate arranged corresponding to the first mass block and each second electrode plate arranged corresponding to the second mass block.

[0013] Furthermore, when the triaxial MEMS sensor vibrates along the Z-axis, the first mass block and the second mass block move in opposite directions out of plane, and the distance between the first mass block and the first electrode plate and the distance between the second mass block and the second electrode plate increase and decrease respectively.

[0014] Furthermore, the first mass block has a hollow structure.

[0015] Furthermore, there are two support beams arranged in parallel, and both ends of the support beams are fixed to the base by anchor points. The first mass block and the second mass block are located between the two support beams, and both ends of the first vibration elastic element are respectively connected to the two support beams.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] In the triaxial MEMS inertial sensor of this invention, motion detection in three directions (XYZ) is achieved by arranging three capacitor detection structures on the same substrate. At the same time, through the layout and structural design of the vibrating elastic element and the detection capacitor components of each axis, the detection in each direction does not interfere with each other. This integrated triaxial MEMS sensor reduces the device area, the overall structure size and the final package size, has small process deviations between different axes, high performance consistency between different axes, and improves the detection accuracy of each axis.

[0018] The present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the triaxial MEMS inertial sensor of the present invention;

[0020] Figure 2 This is a schematic diagram of the vibration of the triaxial MEMS inertial sensor of the present invention along the X-axis;

[0021] Figure 3 This is a schematic diagram of the vibration of the triaxial MEMS inertial sensor of the present invention along the Y-axis;

[0022] Figure 4 This is a schematic diagram of the vibration of the triaxial MEMS inertial sensor of the present invention along the Z-axis.

[0023] Explanation of reference numerals in the attached drawings: 1. First mass block; 2. First vibrating elastic element; 3. Support beam; 4. Second mass block; 5. First pole plate; 6. Second vibrating elastic element; 7. X-axis detection frame; 8. X-axis detection moving comb tooth; 9. X-axis detection fixed comb tooth; 10. Hollow block; 11. Anchor point; 12. Second pole plate; 13. Y-axis detection pole plate; 14. Y-axis detection frame. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] In the description of this invention, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0026] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation", "connection", and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, an abutting connection, or an integral connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0027] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature; in the description of this invention, unless otherwise stated, "a plurality of" or "several" means two or more.

[0028] like Figures 1 to 4As shown, this embodiment provides a triaxial MEMS inertial sensor, including a substrate (not shown in the figure), a first mass block 1, a second mass block 4, an X-axis detection capacitor assembly, a Y-axis detection capacitor assembly, and a Z-axis detection capacitor assembly. The first mass block 1 and the second mass block 4 are both movable sensitive mass blocks. The first mass block 1 and the second mass block 4 are supported on the base by the support beam 3, and a first vibration elastic element 2 is connected between the first mass block 1 and the second mass block 4. Specifically, the first vibration elastic element 2 is fixed to the base by the anchor point 11 and is arranged in parallel between the first mass block 1 and the second mass block 4. Both the first mass block 1 and the second mass block 4 are connected to the first vibration elastic element 2. The X-axis detection capacitor assembly is nested inside the first mass block 1 by the second vibration elastic element 6. The Y-axis detection capacitor assembly includes a Y-axis detection frame 14 and at least two Y-axis detection plates 13. The Y-axis detection frame 14 is nested inside the second mass block 4. The Y-axis detection plates 13 are connected to the base, and the projection of the Y-axis detection frame 14 on the base covers the Y-axis detection plates 13. The Z-axis detection capacitor assembly is disposed on the base corresponding to the first mass block 1 and the second mass block 4. The Y-axis detection frame 14 can be made directly from electrode material, or it can have an electrode structure corresponding to each Y-axis detection electrode 13, so that the overlapping area between the Y-axis detection frame 14 and the Y-axis detection electrode 13 can form a detection capacitor.

[0029] In this embodiment, the first vibrating elastic element 2 can be, but is not limited to, a vibrating spring. The first vibrating elastic element 2 bends in the Y-axis direction, and simultaneously allows the first mass block 1 and the second mass block 2 to move along the Z-axis direction. The second vibrating elastic element 6 can extend and retract along the X-axis direction, and can be, but is not limited to, a vibrating spring, a flexible U-beam, or an O-beam. The movement in the X-axis and Y-axis directions is in-plane movement parallel to the base, and the movement in the Z-axis direction is out-of-plane movement. The X-axis direction is defined as... Figure 1 Left and right directions, Y-axis direction is Figure 1 The vertical direction and the Z-axis direction are as follows: Figure 1 The direction perpendicular to the front and back of the paper.

[0030] Specifically, such as Figures 2 to 4As shown, when the triaxial MEMS inertial sensor vibrates along the X-axis, the second vibration elastic element 6 provides stiffness during vibration, and the X-axis detection capacitor assembly moves along the X-axis direction, generating a change in capacitance value, thus enabling the triaxial MEMS inertial sensor to detect parameters in the X-direction. When the triaxial MEMS inertial sensor vibrates along the Y-axis, the overlapping area between the Y-axis detection frame 14 and the Y-axis detection electrode 13 changes, thereby generating a change in capacitance value, thus enabling the triaxial MEMS inertial sensor to detect parameters in the Y-direction. When the triaxial MEMS inertial sensor vibrates along the Z-axis, the first mass block 1 and the second mass block 4 move in opposite directions out of plane, and the detection capacitance values ​​generated between the Z-axis detection capacitor assembly and the corresponding mass block increase and decrease respectively. The two sets of capacitors form a differential capacitor, which increases the capacitance detection signal. At the same time, the differential reduces the common-mode error signal, thus enabling the triaxial MEMS inertial sensor to accurately detect parameters in the Z-direction. This embodiment achieves motion detection in three directions (XYZ) by arranging three capacitive sensing structures on the same substrate. This integrated triaxial MEMS sensor reduces the device area, the overall structure size, and the final package size. Furthermore, it exhibits small process deviations between different axes and high performance consistency across different axes.

[0031] In the optimized implementation, when the second mass block 4 vibrates along the Y-axis, the overlapping area of ​​at least one of the Y-axis detection plates 13 and the Y-axis detection frame 14 increases, while the overlapping area of ​​at least one of the Y-axis detection plates 13 and the Y-axis detection frame 14 decreases. This structural design ensures that the detection capacitance value generated between the Y-axis detection frame 14 and the Y-axis detection plate 13 has at least one increase and one decrease. The increased and decreased capacitance forms a differential capacitance, which increases the capacitance detection signal. At the same time, the differential capacitance reduces the common-mode error signal, thereby improving the capacitance detection accuracy in the Y-axis direction.

[0032] In some embodiments, a specific structural design and layout of the Y-axis sensing capacitor assembly is provided, such as... Figure 1 and Figure 3 As shown, a through hole is formed in the second mass block 4, which penetrates the second mass block 4 along the Z-axis. The Y-axis detection frame 14 is located in the through hole, and its two ends along the X-axis are connected to the second mass block 4. There are two Y-axis detection plates 13, which are arranged in parallel and staggered along the X-axis. When the second mass block 4 vibrates along the Y-axis, the capacitance formed between the Y-axis detection frame 14 and the two Y-axis detection plates 13 increases and decreases, and the two sets of capacitances form a differential capacitor, which increases the capacitance detection signal and at the same time reduces the common-mode error signal.

[0033] Furthermore, it can be designed so that when the triaxial MEMS inertial sensor vibrates along the Z-axis, the change in distance between each of the Y-axis detection plates 13 and the Y-axis detection frame 14 is the same. This design achieves mutual isolation between Z-direction motion and Y-direction motion. Specifically, taking the design of two Y-axis detection plates as an example, when the triaxial MEMS inertial sensor vibrates along the Z-axis and the Y-axis detection frame 14 vibrates synchronously in the corresponding direction with the second mass block 4, by designing the relative positions of the two Y-axis detection plates 13 and the Y-axis detection frame 14, the change in distance between the Y-axis detection frame 14 and the two Y-axis detection plates 13 is synchronized. In this way, the change in capacitance between the Y-axis detection frame 14 and the two Y-axis detection plates 13 is synchronized, and its differential output is zero, that is, the Y-direction capacitance value does not change. This indicates that the vibration of the triaxial MEMS sensor along the Z-axis has no effect on the Y-direction capacitance output, and the Z-direction motion and Y-direction motion are mutually isolated, with no motion coupling.

[0034] Optional implementation methods, such as Figure 1 and Figure 2 As shown, the X-axis detection capacitor assembly includes an X-axis detection frame 7 and at least two sets of X-axis detection moving comb teeth 8 and at least two sets of X-axis detection fixed comb teeth 9 disposed within the X-axis detection frame 7. A through hole can be formed on the first mass block 1, which penetrates the first mass block 1 along the Z-axis direction. Preferably, the through hole is located at the center of the first mass block 1. The X-axis detection frame 7 is placed in the through hole, and the two ends of the X-axis detection frame 7 along the X-axis direction are connected to the first mass block 1 through a second vibration elastic member 6. The second vibration elastic member 6 can extend and retract along the X-axis direction. The X-axis detection moving comb tooth 8 is connected to the X-axis detection frame 7, and the X-axis detection fixed comb tooth 9 is fixed to the base through anchor points 11. Each comb tooth of the X-axis detection fixed comb tooth 9 extends at least partially into the gap between the corresponding X-axis detection moving comb tooth 8. When the first mass block 1 vibrates along the X-axis, the capacitance value between at least one set of X-axis detection fixed comb teeth 9 and the corresponding X-axis detection moving comb tooth 8 increases, while the capacitance value between at least one set of X-axis detection fixed comb teeth 9 and the corresponding X-axis detection moving comb tooth 8 decreases. In this way, the capacitance values ​​increase and decrease, and the difference between the two capacitances forms a differential capacitance, which increases the capacitance detection signal and reduces the common-mode error signal. In this embodiment, at least one set of X-axis detection moving comb teeth 8 is connected to the upper and lower sides inside the X-axis detection frame 7. The openings of the X-axis detection moving comb teeth 8 on the upper and lower sides are both along the X-axis direction but in opposite directions. Thus, when the triaxial MEMS sensor vibrates along the X-axis, the overlapping area of ​​the upper X-axis detection moving comb tooth 8 and the corresponding X-axis detection fixed comb tooth 9 will increase and decrease respectively with the overlapping area of ​​the lower X-axis detection moving comb tooth 8 and the corresponding X-axis detection fixed comb tooth 9. That is, the capacitance values ​​on the upper and lower sides will increase and decrease respectively, and the difference between the capacitance values ​​at both ends will form a differential capacitor. Furthermore, when the first mass block 1 moves in the X-axis direction, such as... Figure 2As shown, due to the supporting effect of the first vibration elastic element 2 and the second vibration elastic element 6, the vibration frequencies in the three directions can be effectively separated. When the first mass block 1 moves in the X-axis direction, the other positions of the triaxial MEMS sensor structure remain stationary, which realizes that the X-axis movement is isolated from the Y and Z-axis movements, with no motion coupling, thus improving the accuracy of X-axis detection.

[0035] In the preferred embodiment, when the triaxial MEMS sensor vibrates along the Y-axis or Z-axis, the spacing change between the X-axis moving comb teeth 8 and the corresponding X-axis fixed comb teeth 9 in each group is the same. Specifically, when the triaxial MEMS sensor vibrates along the Y-axis or Z-axis, and the X-axis detection frame 7 vibrates synchronously in the corresponding direction with the first mass block 1, the spacing change between the upper X-axis moving comb teeth 8 and the corresponding X-axis fixed comb teeth 9 inside the X-axis detection frame 7 is synchronized with the spacing change between the lower X-axis moving comb teeth 8 and the corresponding X-axis fixed comb teeth 9 inside the X-axis detection frame 7. In this way, the capacitance change on the upper and lower sides of the X-axis detection frame 7 is synchronized, and its differential output is zero, that is, the capacitance value will not change. The vibration of the triaxial MEMS sensor along the Y-axis or Z-axis has no effect on the capacitance output in the X direction, realizing that the Y or Z direction motion is isolated from the X direction motion and there is no motion coupling.

[0036] Optional implementation methods, such as Figure 1 and Figure 4 As shown, the Z-axis detection capacitor assembly includes at least one first electrode plate 5 and at least one second electrode plate 12 disposed on the substrate. Each first electrode plate 5 is arranged corresponding to the first mass block 1, and each second electrode plate 12 is arranged corresponding to the second mass block 4. Both the first mass block 1 and the second mass block 4 can be directly made of electrode material, or they can have electrode plate structures corresponding to the first electrode plate 5 and the second electrode plate 12, so that the overlapping area between the mass block and the corresponding electrode plate can form a detection capacitor. When the triaxial MEMS sensor vibrates along the Z-axis, the first mass block 1 and the second mass block 4 move in opposite directions out of plane. At this time, the distance between the first mass block 1 and the first electrode plate 5 and the distance between the second mass block 4 and the second electrode plate 12 increase and decrease respectively, resulting in an increase and decrease in the detection capacitor. The two sets of capacitors form a differential capacitor, increasing the capacitance detection signal. Simultaneously, the differential capacitance subtracts the common-mode error signal, enabling the triaxial MEMS sensor to accurately detect parameters in the Z-direction.

[0037] Specifically, in this embodiment, the X-axis detection capacitor assembly and the Y-axis detection capacitor assembly are located at the centers of the first mass block 1 and the second mass block 4, respectively. There are two first electrode plates 5, which are respectively disposed at both ends of the X-axis detection capacitor assembly along the X-axis direction. There are two second electrode plates 12, which are respectively disposed at both ends of the Y-axis detection capacitor assembly along the X-axis direction. Preferably, the two first electrode plates 5 and the two second electrode plates 12 are arranged symmetrically about the first vibrating elastic element 2.

[0038] When the triaxial MEMS sensor vibrates along the Z-axis, the X-axis detection frame 7, nested inside the first mass block 1, vibrates synchronously with the first mass block 1. By designing the fixed X-axis detection comb teeth 9 on the upper and lower sides inside the X-axis detection frame 7, the change in the distance between the fixed X-axis detection comb teeth 9 and the movable X-axis detection comb teeth 8 on the upper side is synchronized with the change in the distance between the fixed X-axis detection comb teeth 9 and the movable X-axis detection comb teeth 8 on the lower side. In this way, the capacitance change on the upper and lower sides inside the X-axis detection frame 7 is synchronized, and its differential output is zero, that is, the capacitance value will not change. This shows that the vibration of the triaxial MEMS sensor along the Z-axis has no effect on the capacitance output in the X direction. The Z-direction motion and the X-direction motion are isolated from each other and there is no motion coupling. When the triaxial MEMS sensor vibrates along the Z-axis, the Y-axis detection frame 14, nested inside the second mass block 4, vibrates synchronously with the second mass block 4. By designing the relative positions of the two Y-axis detection plates 13 and the Y-axis detection frame 14, the spacing change between the Y-axis detection frame 14 and the two Y-axis detection plates 13 is synchronized. In this way, the capacitance change between the Y-axis detection frame 14 and the two Y-axis detection plates 13 is synchronized, and its differential output is zero, that is, the capacitance value in the Y direction will not change. This shows that the vibration of the triaxial MEMS sensor along the Z-axis has no effect on the capacitance output in the Y direction. The Z-direction motion and the Y-direction motion are isolated from each other and there is no motion coupling.

[0039] In an optimized implementation, the first mass block 1 is designed to have a hollow structure. In this embodiment, the hollow structure is a plurality of hollow cubes 10 arranged in an array. The hollow cubes 10 are formed by holes that penetrate the first mass block 1 along the Z-axis. The hollow structure designed on the first mass block 1 in this embodiment can, on the one hand, make the masses of the first mass block 1 and the second mass block 4 unequal, thereby generating swing in the Z direction; on the other hand, the hollow structure design can reduce the damping of the swing in the Z direction.

[0040] In the optimized implementation, the triaxial MEMS sensor of this embodiment is designed with two support beams arranged in parallel. The two ends of the support beams 3 are fixed to the base through anchor points 11. The first mass block 1 and the second mass block 4 are located between the two support beams 3, and the two ends of the first vibration elastic element 2 are respectively connected to the two support beams 3. Through the design of the support beams 3, a stable support is formed for the movement of the first mass block 1 and the second mass block 4, thereby improving the detection accuracy of the triaxial MEMS sensor.

[0041] It should be noted that, in this invention, Figure 2 , Figure 3 and Figure 4 The diagram shows the final motion state of the movable parts of a triaxial MEMS sensor vibrating along the X, Y, and Z axes. To demonstrate the motion effect, the displacement of the movable parts in the diagram has been exaggerated.

[0042] The above examples are merely illustrative of the present invention and do not constitute a limitation on the scope of protection of the present invention. All designs that are the same as or similar to the present invention are within the scope of protection of the present invention.

Claims

1. A triaxial MEMS inertial sensor, characterized in that: The system includes a base, a first mass block, a second mass block, an X-axis detection capacitor assembly, a Y-axis detection capacitor assembly, and a Z-axis detection capacitor assembly. The first and second mass blocks are supported on the base by a support beam, and a first vibration elastic element connects the first and second mass blocks. The X-axis detection capacitor assembly is nested inside the first mass block via a second vibration elastic element. The Y-axis detection capacitor assembly includes a Y-axis detection frame and at least two Y-axis detection plates. The Y-axis detection frame is nested inside the second mass block, and the Y-axis detection plates are connected to the base. The projection of the Y-axis detection frame onto the base covers the Y-axis detection plates. The Z-axis detection capacitor assembly is disposed on the base corresponding to the first and second mass blocks.

2. The triaxial MEMS inertial sensor as described in claim 1, characterized in that: When the second mass block vibrates along the Y-axis, the overlapping area of ​​at least one of the Y-axis detection plates and the Y-axis detection frame increases, while the overlapping area of ​​at least one of the Y-axis detection plates and the Y-axis detection frame decreases.

3. The triaxial MEMS inertial sensor as described in claim 2, characterized in that: There are two Y-axis detection plates, which are arranged in parallel and staggered positions in the X-axis direction.

4. The triaxial MEMS inertial sensor as described in claim 2, characterized in that: The second mass block has a through hole that extends through the second mass block along the Z-axis. The Y-axis detection frame is located inside the through hole, and both ends of the Y-axis detection frame are connected to the second mass block along the X-axis.

5. The triaxial MEMS inertial sensor as described in claim 2, characterized in that: When the triaxial MEMS inertial sensor vibrates along the Z-axis, the distance between each Y-axis detection plate and the Y-axis detection frame changes by the same amount.

6. The triaxial MEMS inertial sensor as described in claim 1, characterized in that: The X-axis detection capacitor assembly includes an X-axis detection frame and at least two sets of X-axis detection movable comb teeth and at least two sets of X-axis detection fixed comb teeth disposed within the X-axis detection frame. The X-axis detection frame is connected to the first mass block via a second vibration elastic element. The X-axis detection movable comb teeth are connected to the X-axis detection frame, and the X-axis detection fixed comb teeth are fixed to the base via anchor points. When the first mass block vibrates along the X-axis, the capacitance value between at least one set of X-axis detection fixed comb teeth and the corresponding X-axis detection movable comb teeth increases, while the capacitance value between at least one set of X-axis detection fixed comb teeth and the corresponding X-axis detection movable comb teeth decreases.

7. The triaxial MEMS inertial sensor as described in claim 1, characterized in that: The Z-axis detection capacitor assembly includes at least one first electrode plate and at least one second electrode plate disposed on the substrate, with each first electrode plate arranged corresponding to the first mass block and each second electrode plate arranged corresponding to the second mass block.

8. The triaxial MEMS inertial sensor as described in claim 7, characterized in that: When the triaxial MEMS sensor vibrates along the Z-axis, the first mass block and the second mass block move in opposite directions out of plane, and the distance between the first mass block and the first electrode plate and the distance between the second mass block and the second electrode plate increase and decrease respectively.

9. The triaxial MEMS inertial sensor as described in claim 1, characterized in that: The first mass block has a hollow structure.

10. The triaxial MEMS inertial sensor as described in claim 1, characterized in that: There are two support beams arranged in parallel. The two ends of the support beams are fixed to the base by anchor points. The first mass block and the second mass block are located between the two support beams, and the two ends of the first vibrating elastic element are respectively connected to the two support beams.

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