A quasi-zero stiffness MEMS accelerometer based on bistable beam-straight beam design

Abstract

The application discloses a quasi-zero stiffness MEMS accelerometer based on a bistable beam-straight beam design and belongs to the technical field of accelerometers. The accelerometer comprises a sensitive mass block, a driving comb tooth module, a bistable beam-straight beam series connection module and a detection comb tooth module. The sensitive mass block is connected with mass block fixed support anchor points through a pair of bistable beam-straight beam series connection modules at four azimuth angles. The driving comb tooth module is located on the upper and lower sides of the sensitive mass block, and the detection comb tooth module is located on the left and right sides of the sensitive mass block. The bistable beam in the bistable beam-straight beam series connection module is a one-half period cosine function structure, one end of which is fixedly connected with the sensitive mass block, the other end of which is connected in series with one end of the straight beam, and the other end of the straight beam is fixedly connected with the mass block fixed support anchor points. The pair of bistable beam-straight beam series connection modules at each azimuth angle of the sensitive mass block are parallel, equidistant and have consistent arch directions. The application can greatly improve the measurement sensitivity of the micro mechanical accelerometer and significantly reduce the driving voltage.

Description

Technical Field

[0001] The present invention relates to the technical field of quasi-zero-stiffness (Quasi-Zero-Stiffness) force balance MEMS (Micro-Electro-Mechanical System) accelerometers, and in particular to a quasi-zero-stiffness MEMS accelerometer based on a bistable beam-straight beam design. Background Art

[0002] MEMS sensors, with their advantages of small size, light weight, and low cost, have found widespread application in manufacturing, healthcare, defense, aerospace, and other fields. With their continued performance improvements, MEMS sensors have also begun to be used in resource exploration and geophysical applications, including earthquake monitoring, earth tide monitoring, volcanic activity monitoring for natural disasters; earthquake, gravity, and magnetic resource exploration; drilling process monitoring; and local gravity measurement for gravity-assisted navigation. However, research on quasi-zero-stiffness MEMS accelerometers is relatively limited. Although some devices have been produced and field measurements have yielded relatively satisfactory results, mass production and operational implementation remain limited. Furthermore, there are no internationally established standards for the size, accuracy, and sensitivity of quasi-zero-stiffness MEMS devices. Therefore, research on quasi-zero-stiffness MEMS sensors is still in a period of rapid development, with increasing research both domestically and internationally.

[0003] While numerous concepts have emerged in the design of quasi-zero-stiffness MEMS sensors, the fundamental principle remains the same: achieving zero (or near-zero) system stiffness in the system housing the device's sensitive mass. Zero system stiffness indirectly reflects a system's sensitivity. Based on the linear relationship between stiffness and displacement within a small deformation range (Hooke's law), even small changes in external excitation can cause large displacements in the sensitive mass. This is currently demonstrated in many microgravity accelerometers. Currently, a large portion of quasi-zero-stiffness device designs are primarily designed for vibration isolation. Due to the booming construction industry and the fact that some locations are located in areas prone to natural disasters such as earthquakes, ground vibrations need to be minimized or even eliminated. Vibration isolation platforms are also widely used. For example, devices sensitive to external displacement interference require operation on isolation platforms, and specialized robotic motion requires constant stability at the image acquisition end. However, for these larger or even larger devices, there are manufacturing and design advantages that MEMS devices lack.

[0004] First, the tiny size of MEMS devices must be taken into account. Many intuitively conceivable components, such as springs in the macroscopic sense, cannot be used. Furthermore, any dynamic system involves structures that provide stiffness, whether at the macro or micro-nano scale. There are many structures that can provide positive stiffness in MEMS quasi-zero stiffness devices, the most common of which is a straight beam structure. However, measures for providing negative stiffness are very limited, and the vast majority of researchers' research on MEMS quasi-zero stiffness focuses on finding suitable negative stiffness structures. To date, most related results use static electrodes to provide negative stiffness to offset the positive stiffness generated by the beam structure within a small range, thereby achieving quasi-zero stiffness within a small deformation range. In addition, some people use simple arch beams to achieve quasi-zero stiffness, and reduce the natural frequency of the structure by adjusting the angle between the structure and the horizontal plane. However, both electrostatic negative stiffness and a simple arch-beam structure have limitations. The quasi-zero stiffness range that can be achieved with electrostatic negative stiffness compensation is relatively small due to the nonlinearity of the electrostatic force and the nearly linear stiffness effect of the straight beam deformation. The simple arch-beam structure requires a relatively large driving force, often requiring a higher voltage or a larger number of drive combs. These are all current issues. Summary of the Invention

[0005] In order to solve the above problems, the present invention proposes a quasi-zero stiffness MEMS accelerometer based on a bistable beam-straight beam design, which connects the bistable beam and the straight beam in series to greatly improve the measurement sensitivity of the micromechanical accelerometer.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A quasi-zero stiffness MEMS accelerometer based on a bistable beam-straight beam design includes a sensitive mass block, a driving comb module, a bistable beam-straight beam series module, and a detection comb module;

[0008] The sensitive mass block is connected to the mass block fixed anchor point at four azimuth angles through a pair of bistable beam-straight beam series modules. The driving comb modules are located on the upper and lower sides of the sensitive mass block, and the detection comb modules are located on the left and right sides of the sensitive mass block.

[0009] The bistable beam-straight beam series module includes a bistable beam and a straight beam. The bistable beam is a half-period cosine function structure. One end of the bistable beam is fixedly connected to the sensitive mass block, and the other end of the bistable beam is connected in series with one end of the straight beam. The other end of the straight beam is fixed to the mass block's fixed anchor point, and a metal electrode layer is sputtered on the mass block's fixed anchor point. A pair of bistable beam-straight beam series modules located at each azimuth angle of the sensitive mass block are parallel and equidistant, and the arch directions of the bistable beams in all the bistable beam-straight beam series modules are consistent.

[0010] The bistable arched beam is actually a periodic cosine function in terms of shape, and the expressions of its upper and lower surfaces are as follows:

[0011]

[0012]

[0013] Where t is the thickness of the bistable beam, h is the midpoint arch height of the bistable beam, and l is the length of the bistable beam. To utilize the negative stiffness effect of the bistable beam, the bistable beam needs to be split symmetrically at its center and connected to each end of the sensitive mass. Furthermore, the other end of the bistable beam is connected in series with a straight beam and then connected to a clamped anchor point, forming a constraint similar to a cantilever beam.

[0014] Furthermore, the sensitive mass block moves in one direction, and the moving direction is opposite to the initial arch direction of the bistable beam in the bistable beam-straight beam series module.

[0015] Furthermore, the thickness of the bistable beam and the straight beam in the bistable beam-straight beam series module are consistent, and the length ratio is (1-3):1.

[0016] Furthermore, the ratio of the arch height to the arch thickness of the bistable beam is 1.2 to 1.67.

[0017] Furthermore, the driving comb module includes a first driving comb and a second driving comb located on the upper and lower sides of the sensitive mass block;

[0018] The first driving comb teeth are composed of an upper movable comb tooth array fixed on the upper boundary of the sensitive mass block and an upper fixed comb tooth array located above the upper movable comb tooth array, and the upper movable comb tooth array and the upper fixed comb tooth array constitute an upper comb tooth capacitor;

[0019] The second driving comb teeth are composed of a lower movable comb tooth array fixed at the lower boundary of the sensitive mass block and a lower fixed comb tooth array located below the lower movable comb tooth array, and the lower movable comb tooth array and the lower fixed comb tooth array constitute a lower comb tooth capacitor;

[0020] The upper fixed comb tooth array and the lower fixed comb tooth array are respectively fixed to the driving comb tooth fixing anchor points located at the upper and lower sides of the sensitive mass block, and the driving comb tooth fixing anchor points are sputtered with a metal electrode layer.

[0021] Furthermore, the detection comb module includes a first detection comb and a second detection comb located on the left and right sides of the sensitive mass block;

[0022] The first detection comb teeth are composed of a left movable comb tooth array fixed at the left boundary of the sensitive mass block and a left fixed comb tooth array located to the left of the left movable comb tooth array, and the left movable comb tooth array and the left fixed comb tooth array constitute a left comb tooth capacitor;

[0023] The second detection comb teeth are composed of a right movable comb tooth array fixed at the right boundary of the sensitive mass block and a right fixed comb tooth array located to the right of the right movable comb tooth array, and the right movable comb tooth array and the right fixed comb tooth array constitute a right comb tooth capacitor;

[0024] The left fixed comb tooth array and the right fixed comb tooth array are respectively fixed to the detection comb tooth fixed anchor points located on the left and right sides of the sensitive mass block, and the detection comb tooth fixed anchor points are sputtered with a metal electrode layer.

[0025] The bistable beam employed in the present invention is a bi-stable arched beam. The negative stiffness of a simple bistable beam structure occurs at the point where it buckles. When the beam's midpoint displacement moves from its initial zero state to a horizontal position, the beam's stiffness changes from positive to negative. As the displacement increases further, the beam's stiffness changes again from negative to positive. While the change in force and displacement is theoretically continuous, achieving this continuity is extremely difficult in practice. Because the applied force increases gradually, it is impossible to immediately reduce the applied force when the beam first experiences negative stiffness. Therefore, as the midpoint displacement of the bistable beam increases, the entire beam structure undergoes a sudden change at the point where the stiffness first changes. This sudden change is critical for MEMS accelerometers. With current manufacturing processes and raw materials, excessive displacement changes or sudden changes are highly likely to cause device fracture. Furthermore, purely negative stiffness devices are not widely used and are of limited significance. Therefore, a positive stiffness structure is needed to offset the negative stiffness.

[0026] When a bistable beam experiences negative stiffness, the driving force required is already substantial. If masses are directly connected to the proof mass, this straight beam connection significantly increases the driving force required to reach the quasi-zero stiffness range of the MEMS accelerometer. This requires a very high voltage or a large number of drive combs. Considering factors such as the allowable voltage range for normal function of circuit components, the driving voltage should not be too high. Using a lower voltage inevitably results in a significant increase in the number of drive combs required. This increase in combs increases device size and manufacturing costs; it also increases the mass of the sensitive mass, which is carried by the beam and should not be too large.

[0027] The present invention uses a straight beam and a bistable beam in series to design a quasi-zero stiffness MEMS accelerometer. The straight beam and the bistable beam in series can also produce a quasi-zero stiffness range within the allowable range of beam deformation, which has the following advantages:

[0028] First, the length of the quasi-zero stiffness interval is comparable to or even exceeds that of traditional methods, enabling MEMS accelerometers to have a larger dynamic measurement range.

[0029] Second, the series connection strategy requires much less straight beam length than the non-series connection strategy for a bistable beam with the same horizontal span, which can greatly reduce the size of the entire device.

[0030] Third, and most importantly, the design method proposed in this invention can significantly reduce the required driving force. Through theoretical derivation and experimental simulation analysis, for a bistable beam with the same horizontal span, the required driving force is only 1 / 4 of that of a simple bistable beam structure and 1 / 9 of that of a non-series straight beam, representing a breakthrough in magnitude.

[0031] To ensure that the driving electrostatic force does not vary with the displacement of the sensitive mass, the present invention employs a constant voltage drive. Under this electrostatic driving force, the displacement change at the end of the sensitive mass needs to be detected as a system response. The present invention calculates the displacement of the sensitive mass based on the change in the parallel plate capacitance. Therefore, detection comb structures are designed on both sides of the device to detect displacement changes. Because the beam cross-section is rectangular and deformation is minimal, the movement of the entire structure is in-plane and symmetrical. This ensures that the displacements at both ends of the device are equal, preventing calculation errors.

[0032] In summary, the present invention provides a MEMS quasi-zero-stiffness accelerometer based on a bistable beam-straight beam series connection. By utilizing the mutual compensation mechanism between the negative stiffness of the bistable beam and the locally linear positive stiffness of the series-connected straight beam, a localized quasi-zero-stiffness effect is generated. This overcomes the high-frequency characteristics of traditional MEMS devices, significantly improves the measurement sensitivity of the micromachined accelerometer, and significantly reduces the drive voltage of the driver module, thus paving the way for the development of micromachined quasi-zero-stiffness accelerometers. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 1. This is an enlarged view of the entire structure and local details of a quasi-zero stiffness MEMS accelerometer based on a bistable beam-straight beam design provided by an embodiment of the present invention;

[0034] Figure 2 The bi-stable beam-straight beam series diagram of the present invention is shown in (a) a front view, (b) a top view, and (c) a three-dimensional view.

[0035] Figure 3 It is a power supply circuit diagram of the present invention;

[0036] Figure 4 Schematic diagram of the structure of a quasi-zero stiffness MEMS accelerometer based on a bistable beam-straight beam design provided by an embodiment of the present invention;

[0037] Figure 5 is the force-displacement diagram of the bistable beam;

[0038] Figure 6 is the force-displacement diagram of a straight beam;

[0039] Figure 7 It is a force-displacement relationship diagram of the present invention.

[0040] In the picture:

[0041] 1-1 Sensitive mass block 5-1 First fixed anchor point

[0042] 2-1 First driving comb teeth 5-2 First metal electrode layer

[0043] 2-2 Second drive comb tooth 5-3 Second fixed anchor point

[0044] 3-1 first bistable beam 5-4 second metal electrode layer

[0045] 3-2 First straight beam 5-5 Third fixed anchor point

[0046] 3-3 second bistable beam 5-6 third metal electrode layer

[0047] 3-4 Second straight beam 5-7 Fourth fixed anchor point

[0048] 3-5 third bistable beam 5-8 fourth metal electrode layer

[0049] 3-6 third straight beam 5-9 fifth fixed anchor point

[0050] 3-7 fourth bistable beam 5-10 fifth metal electrode layer

[0051] 3-8 Fourth straight beam 5-11 Sixth fixed anchor point

[0052] 3-9 fifth bistable beam 5-12 sixth metal electrode layer

[0053] 3-10 Fifth straight beam 5-13 Seventh fixed anchor point

[0054] 3-11 Sixth bistable beam 5-14 Seventh metal electrode layer

[0055] 3-12 Sixth straight beam 5-15 Eighth fixed anchor point

[0056] 3-13 Seventh bistable beam 5-16 Eighth metal electrode layer

[0057] 3-14 Seventh straight beam 5-17 Ninth fixed anchor point

[0058] 3-15 eighth bistable beam 5-18 ninth metal electrode layer

[0059] 3-16 Eighth straight beam 5-19 Tenth fixed anchor point

[0060] 4-1 first detection comb tooth 5-20 tenth metal electrode layer

[0061] 4-2 Second detection comb 6-1 First limit column

[0062] 4-3 Third detection comb 6-2 Second limit column

[0063] 4-4 Fourth detection comb DETAILED DESCRIPTION

[0064] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0065] The present invention provides a quasi-zero stiffness MEMS accelerometer based on a bistable beam-straight beam tandem design. By combining the local linear positive stiffness of the straight beam with the negative stiffness of the bistable arched beam, the overall stiffness of the accelerometer structure can be locally quasi-zero stiffness, significantly reducing the driving force required for the bistable beam and significantly improving the system sensitivity. This opens new avenues for research and application of MEMS quasi-zero stiffness.

[0066] Reference Figure 1 and Figure 4 The present invention includes six modules, namely, a sensitive mass module, a driving comb module, a bistable beam-straight beam series module, a detection comb module, a fixed support anchor module and a limit module.

[0067] The sensitive mass module is the main body, and the movement of the sensitive mass block 1-1 is unidirectional, which is determined by the arch direction of the arch beam. The movement of the sensitive mass block 1-1 is opposite to the initial arch direction of the arch beam, and always maintains in-plane movement. The so-called in-plane movement means that the movement of the sensitive mass block 1-1 always remains parallel to the plane of the entire accelerometer, so as to avoid the complex nonlinear dynamic behavior that may be generated by the beam structure. The sensitive mass block 1-1 can move because the sensitive mass block 1-1 needs to be etched and suspended in the air when manufacturing the device, and the structure that supports its suspension is the beam structure. The subsequent bistable beam-arch beam series module will be explained in detail. In addition, the sensitive mass block 1-1 is driven by the driving force generated by the comb module.

[0068] The driving comb module includes two parts of the comb structure, namely Figure 4 The first drive comb 2-1 and the second drive comb 2-2 are shown. Both the first drive comb 2-1 and the second drive comb 2-2 include two comb arrays. First, let's look at the first drive comb 2-1. Figure 1It can be seen that the first drive comb 2-1 includes two upper and lower comb arrays. The upper comb array is connected to the first fixed anchor point 5-1 and is fixed and cannot move. The lower comb array is fixed to the upper boundary of the sensitive mass block 1-1 and moves in the same manner as the sensitive mass block 1-1. Similarly, the upper drive comb array of the second drive comb 2-2 is fixed to the lower boundary of the sensitive mass block 1-1 and moves in the same manner as the sensitive mass block 1-1. The lower drive comb array is fixed to the sixth fixed anchor point 5-11 and cannot move. In order for the movement of the sensitive mass block 1-1 to conform to the design, it is necessary to make the first drive comb 2-1 generate a repulsive force or the second drive comb 2-2 generate an attractive force. To generate a repulsive force or attractive force between the comb teeth, it is first necessary to generate a level difference between the comb teeth. The voltage of the comb array connected to the sensitive mass 1-1 is consistent with that of the sensitive mass 1-1. Generally, the voltage of the sensitive mass 1-1 is set to zero or a small value. The voltage of the sensitive mass is input through the metal electrode layers at the second, fifth, seventh, and tenth clamping anchors. Because these four clamping anchors are interconnected with the beam structure and the sensitive mass, the specific connection method will be explained in detail in the introduction to the bistable beam-straight beam series module. By applying a certain voltage to the first metal electrode layer 5-2 on the first clamping anchor 5-1 or the sixth metal electrode layer 5-12 on the sixth clamping anchor 5-11, the comb array connected to the first clamping anchor 5-1 or the sixth clamping anchor 5-11 is charged with a certain voltage. This creates a voltage difference between the two drive comb arrays in the same drive comb structure, causing the first drive comb 2-1 to generate a repulsive force or the second drive comb 2-2 to generate an attractive force, thereby driving the movement of the sensitive mass 1-1. The suspended movement of the sensitive mass 1-1 is supported by the beam structure.

[0069] The bistable beam-straight beam series module includes eight arch beams and eight straight beams. It should be noted that the bistable beams 3-1, 3-3, 3-5, 3-7, 3-9, 3-11, 3-13 and 3-15 are all half of the bistable arch beam shown in formula (2). Figure 2 The main view and three-dimensional space diagram of the bistable beam-straight beam series are shown in Figure 1. Figure 4In the example, the first bistable beam-straight beam series structure is used. The left end of the first bistable beam 3-1 is fixedly connected to the sensitive mass block 1-1, and its right end is connected to the left end of the first straight beam 3-2. Since the present invention sets the bistable beam and the straight beam to have the same thickness and the same etching depth, the cross-sections of the two beams are the same rectangle. The right end of the first bistable beam 3-1 is completely aligned with and fixed to the left end of the first straight beam 3-2. The right end of the first straight beam 3-2 is fixed to the second fixed anchor point. Through this connection method, the eight bistable beams and straight beams are connected one by one, forming four pairs of bistable beam-straight beam series structures, respectively located at the four azimuth angles of the sensitive mass block, and the arch direction of the bistable beams in each bistable beam-straight beam series structure is consistent. The four pairs of bistable beam-straight beam series structures support the sensitive mass block 1-1 and connect the second support anchor point 5-3, the fifth support anchor point 5-9, the seventh support anchor point 5-13, and the tenth support anchor point 5-19, so that the sensitive mass block can be powered.

[0070] The detection comb module includes Figure 4 The first detection comb teeth 4-1, the second detection comb teeth 4-2, the third detection comb teeth 4-3 and the fourth detection comb teeth 4-4 in the embodiment. Since it is necessary to obtain the force-displacement curve of the sensitive mass block 1-1, the force is given by the driving comb tooth module, and the voltage is known, and the magnitude of the driving force can be calculated by inputting the voltage. However, the displacement is unknown. The present invention obtains the displacement indirectly through the detection comb tooth module, and the first detection comb tooth 4-1 is used as an example for detailed description. Similar to the driving comb tooth module, each detection comb tooth module is divided into two left and right comb tooth arrays. In the first detection comb tooth 4-1, the left comb tooth array is fixed to the sensitive mass block 1-1 and moves with the movement of the sensitive mass block 1-1. The right comb tooth array is fixed to the third fixed anchor point 5-5 and always remains stationary. The left comb tooth array and the right comb tooth array form multiple pairs of parallel plates. The capacitance change between the parallel plates can directly reflect the displacement change of the sensitive mass block 1-1. The MEMS accelerometer needs to be wired before it works, that is, the metal electrode layer on each fixed anchor point is connected to the corresponding terminal. When the sensitive mass moves, the capacitance between the parallel plates of each detection comb module changes, thereby detecting a capacitance change signal representing the displacement of the sensitive mass 1-1 between the third metal electrode layer 5-6, the fourth metal electrode layer 5-8, the eighth metal electrode layer 5-16, and the ninth metal electrode layer 5-18, and the second metal electrode layer 5-4, the fifth metal electrode layer 5-10, the seventh metal electrode layer 5-14, and the tenth metal electrode layer 5-20. The aforementioned anchor points and metal electrode layers are described in detail in the other modules above, so they are not further explained.

[0071] The limiting module is mainly used to limit the displacement of the sensitive mass block 1-1. Figure 1The limit module is an enlarged version of the first limit column 6-1. The limit columns 6-1 and 6-2 are fixed to the first anchor point 5-3 and the tenth anchor point 5-19 respectively. The distance between their ends and the sensitive mass block 1-1 is 12um, which limits the maximum displacement of the sensitive mass block 1-1 to 12um. In terms of device manufacturing, the general arch beam has two stable states (i.e., two energy potential wells), provided that the ratio of arch height to arch thickness is It needs to be controlled within a certain range. After theoretical derivation and simulation experimental analysis, two energy potential wells can appear when Q≥1.2, but after Q≥1.67, the accelerometer will have asymmetric high-order modes, which need to be avoided during the design process. Furthermore, the material properties of the device need to be considered. Silicon, as the most commonly used raw material for MEMS device manufacturing, has too low bending resistance and too high brittleness. Therefore, combined with the above-mentioned bistable beam principle and material limitations, the ratio of arch height to arch thickness of the bistable beam of the present invention is set at Q=1.5, where the arch thickness is set to 4um and the arch height is set to 6um. In addition, as a MEMS, device size is one of the main considerations. At present, the main processing technology of MEMS is still SOI (Silicon on Insulator). The minimum size that can be made by domestic foundries in the SOI process is 2um, and the maximum aspect ratio that can be achieved by deep trench etching at 2um is 40:1. Therefore, all comb tooth structures involved in the structure of the present invention adopt a thickness of 4um, the length of the driving comb teeth is 80um, and the length of the detection comb teeth is 200um. The length of a single-sided straight beam is 200um, the length of a semi-arch beam is 400um, and the etching depth required for the structure is 30um.

[0072] In summary, the driving force and displacement are explained in detail. Figure 5 is the force-displacement diagram of the bistable beam, Figure 6 is the force-displacement diagram of a straight beam, Figure 7 This is the force-displacement relationship diagram of the bistable beam-straight beam series structure of the present invention, from Figure 7 As can be seen, during device operation, the applied drive voltage must be kept within a narrow range, requiring a slow change as the system stiffness approaches zero stiffness. Once the device reaches the quasi-zero stiffness range, the actual stiffness remains positive, albeit at a very low value. Therefore, the drive voltage must be fine-tuned to stabilize the device roughly in the middle of the quasi-zero stiffness range. This allows the accelerometer to measure excitation in both directions and maintain consistent bidirectional measurement ranges.

[0073] Acceleration measurement is performed under the premise that the sensitive mass 1-1 is within the quasi-zero stiffness range. To ensure that the sensitive mass 1-1 remains within this quasi-zero stiffness range and maintains high precision and sensitivity under external acceleration, a closed-loop feedback control algorithm is required. The key concept behind the force balance accelerometer is to minimize the displacement of the sensitive mass 1-1 by designing an optimal feedback control strategy. Because the feedback driving force is applied to the sensitive mass via the first and second drive combs 2-1 and 2-2 to balance the external acceleration excitation, the magnitude of the external acceleration can be represented by the quotient of the feedback driving force and the weight of the sensitive mass 1-1.

[0074] The above content is only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A quasi-zero stiffness MEMS accelerometer based on a bistable beam-straight beam design, characterized in that: It includes a sensitive mass block, a driving comb module, a bistable beam-straight beam series module, and a detection comb module; The sensitive mass block is connected to the mass block fixed anchor point at four azimuth angles through a pair of bistable beam-straight beam series modules. The driving comb modules are located on the upper and lower sides of the sensitive mass block, and the detection comb modules are located on the left and right sides of the sensitive mass block. The bistable beam-straight beam series module includes a bistable beam and a straight beam. The thickness of the bistable beam and the straight beam are consistent, the length ratio is (1-3):1, and the ratio of the arch height to the arch thickness of the bistable beam is 1.2-1.

67. The bistable beam is a half-period cosine function structure. One end of the bistable beam is fixedly connected to the sensitive mass block, the other end of the bistable beam is connected in series with one end of the straight beam, and the other end of the straight beam is fixed to the mass block fixed anchor point. A metal electrode layer is sputtered on the mass block fixed anchor point. A pair of bistable beam-straight beam series modules located at each azimuth angle of the sensitive mass block are parallel and equidistant, and the arch directions of the bistable beams in all the bistable beam-straight beam series modules are consistent.

2. The quasi-zero stiffness MEMS accelerometer based on a bistable beam-straight beam design according to claim 1, characterized in that: The sensitive mass block moves in one direction, and the moving direction is opposite to the initial arch direction of the bistable beam in the bistable beam-straight beam series module.

3. The quasi-zero stiffness MEMS accelerometer based on a bistable beam-straight beam design according to claim 1, characterized in that: The driving comb module comprises a first driving comb (2-1) and a second driving comb (2-2) located on the upper and lower sides of the sensitive mass block; The first driving comb teeth (2-1) are composed of an upper movable comb tooth array fixed on the upper boundary of the sensitive mass block and an upper fixed comb tooth array located above the upper movable comb tooth array, wherein the upper movable comb tooth array and the upper fixed comb tooth array form an upper comb tooth capacitor; The second driving comb teeth (2-2) are composed of a lower movable comb tooth array fixed at the lower boundary of the sensitive mass block and a lower fixed comb tooth array located below the lower movable comb tooth array, and the lower movable comb tooth array and the lower fixed comb tooth array form a lower comb tooth capacitor; The upper fixed comb tooth array and the lower fixed comb tooth array are respectively fixed to the driving comb tooth fixing anchor points located at the upper and lower sides of the sensitive mass block, and the driving comb tooth fixing anchor points are sputtered with a metal electrode layer.

4. The quasi-zero stiffness MEMS accelerometer based on a bistable beam-straight beam design according to claim 1, characterized in that: The detection comb module comprises a first detection comb (4-1) and a second detection comb (4-2) located on the left and right sides of the sensitive mass block; The first detection comb (4-1) is composed of a left movable comb array fixed at the left boundary of the sensitive mass block and a left fixed comb array located on the left side of the left movable comb array, wherein the left movable comb array and the left fixed comb array form a left comb capacitor; The second detection comb (4-2) is composed of a right movable comb array fixed at the right boundary of the sensitive mass block and a right fixed comb array located to the right of the right movable comb array, and the right movable comb array and the right fixed comb array constitute a right comb capacitor; The left fixed comb tooth array and the right fixed comb tooth array are respectively fixed to the detection comb tooth fixed anchor points located on the left and right sides of the sensitive mass block, and the detection comb tooth fixed anchor points are sputtered with a metal electrode layer.

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