A quasi-zero stiffness MEMS accelerometer based on suspension parallel design

Abstract

The application discloses a quasi-zero stiffness MEMS accelerometer based on suspension parallel design and belongs to the technical field of quasi-zero stiffness accelerometers. The accelerometer comprises a sensitive mass block, a driving comb tooth module, suspension parallel bistable beam-straight beam series connection modules, and a detection comb tooth module. The upper and lower sides of the sensitive mass block are respectively provided with one suspension parallel bistable beam-straight beam series connection module, the protruding structure located at the middle of the upper and lower sides of the sensitive mass block is connected with the suspension parallel bistable beam-straight beam series connection module on the side, the driving comb tooth module is located at the left and right ends of the lower side of the sensitive mass block, and the detection comb tooth module is located at the left and right sides of the sensitive mass block. The suspension parallel bistable beam-straight beam series connection module comprises a suspension assembly and a beam structure obtained by connecting a bistable beam and a straight beam in series. The application connects a single bistable beam with a single straight beam in series, forms a local quasi-zero stiffness interval, designs multiple parallel mechanisms of the structure in the working plane of the device, and thus achieves quasi-zero stiffness in multiple intervals.

Description

Technical Field

[0001] The present invention relates to the technical field of quasi-zero-stiffness force-balanced MEMS (Micro-Electro-Mechanical System) accelerometers, and in particular to a quasi-zero-stiffness MEMS accelerometer based on a suspension parallel design. Background Art

[0002] Signal measurement can be understood as the problem of signal monitoring. In fields such as industrial sensing and biomedicine, real-time monitoring of signals, whether large or weak, simple or complex, is often crucial. In the sensing field, a series of related sensors are often required to measure the various behaviors of the object being measured, making sensor sensitivity and accuracy a key concern. In the field of accelerometers, liquid pendulum accelerometers, quartz flexure accelerometers, and silicon microaccelerometers have been developed to detect high-value signals. However, these accelerometers all suffer from similar problems: low sensitivity and resolution. The causes of these problems are also similar, ranging from excessive noise from complex circuits to a lack of significant response due to structural rigidity. However, the development of MEMS sensors has made it possible to effectively compensate for these influencing factors.

[0003] Because MEMS sensor circuits are not complex, combining them with optical measurement makes the circuits even simpler and clearer, avoiding significant circuit noise. Furthermore, MEMS, belonging to the micro- and nanoscale fields, typically have low structural stiffness. However, due to their small size, the mass is also reduced, resulting in excessively high frequencies, insufficient low-frequency signal sensitivity, and insufficient signal quality. Therefore, further reducing structural stiffness is necessary, leading to the development of quasi-zero stiffness MEMS sensor designs. As the name suggests, quasi-zero stiffness MEMS devices have a structural stiffness close to zero. A system's near-zero stiffness indirectly reflects its sensitivity. Based on the linear relationship between stiffness and displacement within a small deformation range (Hooke's law), it is known that even small changes in external excitation can cause significant displacements of the sensitive mass. Such results have been applied to various types of microgravity sensors. Sensor designs for micro- and nanoscale structures are generally structurally simple, making overly complex structures less suitable for micro- and nanoscale applications. However, achieving true quasi-zero stiffness is difficult with relatively simple structures.

[0004] Given the tiny size of MEMS devices, many intuitively conceivable components, such as springs in the macroscopic sense, are unusable. Any dynamic system, whether at the macro or microscale, involves structures that provide stiffness. There are many structures capable of providing positive stiffness in MEMS quasi-zero stiffness devices, with a straight beam being the most common. However, methods for providing negative stiffness are limited, and most researchers studying MEMS quasi-zero stiffness have focused on finding suitable negative stiffness structures. To date, most research has used electrostatic plates to provide negative stiffness to offset the positive stiffness of the beam structure within a small range, thereby achieving quasi-zero stiffness within a small deformation range. Alternatively, some researchers have used simple arched beams to achieve quasi-zero stiffness, lowering the natural frequency by adjusting the angle between the structure and the horizontal plane. However, both approaches, using electrostatic negative stiffness or simple arched beam structures, have limitations. For electrostatic negative stiffness offset, the quasi-zero stiffness range is relatively small due to the nonlinearity of the electrostatic force and the nearly linear stiffness effect of the straight beam's deformation. Furthermore, the required driving voltage is generally high, making this impractical. The driving force required for a simple arch beam structure is relatively large, often requiring a higher voltage drive or more drive combs. In addition, considering the size of the overall structure, the beam should not be too long. These are all existing problems. 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 suspension parallel design, in which a single bistable beam is connected in series with a single straight beam to form a local quasi-zero stiffness interval. Multiple parallel mechanisms of this structure are designed within the working plane of the device to achieve quasi-zero stiffness in multiple intervals, thereby broadening the working range of QZS and greatly improving 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 suspension parallel bistable beam-straight beam design includes a sensitive mass block, a drive comb module, a suspension parallel bistable beam-straight beam series module, and a detection comb module.

[0008] The sensitive mass is the movable structure in the center of the device, connected at its top and bottom to a suspension parallel bistable beam-straight beam series module. Furthermore, drive comb modules are also connected to both sides of the sensitive mass. These parallel bistable beam-straight beam series modules provide support for the sensitive mass. To reduce this support and prevent damage to the beam structure, the center of the sensitive mass is hollowed out, leaving a square frame to reduce mass. The drive comb modules are located on either side of the lower portion of the sensitive mass, while the detection comb modules are located on either side of the middle portion of the sensitive mass.

[0009] The suspension parallel-type bistable beam-straight beam series module includes a suspension assembly and a beam structure formed by connecting a bistable beam and a straight beam in series. The overall structure consists of two parts: each suspension parallel-type bistable beam-straight beam series module is located at the upper and lower ends of the sensitive mass, respectively. The total structure includes sixteen bistable beam-mass series beam structures, six movable suspensions, and two fixed anchors. The bistable beams are half-period cosine function structures. The suspension assembly includes fixed anchors and movable suspensions. The fixed anchors are fixed above and below the sensitive mass and sputtered with metal electrode layers. Several movable suspensions are arranged in parallel between the fixed anchors and the raised structures on the upper and lower sides of the sensitive mass. The movable suspension closest to the sensitive mass is connected to the raised structure of the sensitive mass, the movable suspension farthest from the sensitive mass is connected to the fixed anchors, and adjacent movable suspensions are connected by beam structures. A metal electrode layer is sputtered on the fixed anchor point; the two beam structures connecting the central raised structure on the same side of the sensitive mass block and the two beam structures connecting the same part of the same movable suspension form a pair, and the pairs of beam structures located at the upper and lower ends of the sensitive mass block are parallel and equidistant, and the arch direction of the bistable beams in all the beam structures is 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] 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 exploit 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 (or suspension). Furthermore, the other end of the bistable beam is connected in series with a straight beam and then connected to the suspension (or fixed anchor point), forming a constraint similar to a cantilever beam.

[0013] Furthermore, the movement direction of the sensitive mass block is opposite to the initial arch direction of the bistable beam in the beam structure.

[0014] Furthermore, the thickness of the bistable beam and the straight beam in the beam structure are consistent, and the length ratio is (1-3):1.

[0015] Furthermore, the ratio of the arch height to the arch thickness of the bistable beam in the beam structure is 1.2 to 1.67.

[0016] Furthermore, the lengths of the plurality of movable suspensions arranged in parallel between the suspension fixing anchor point and the upper / lower middle protruding structure of the sensitive mass block decrease in sequence.

[0017] Furthermore, the number of the plurality of movable suspensions arranged in parallel is 3-6.

[0018] Furthermore, the driving comb module includes a first driving comb and a second driving comb located on the left and right sides of the lower portion of the sensitive mass block;

[0019] The first driving comb teeth are composed of a first upper movable comb tooth array fixed to the right side of the lower end of the sensitive mass block and a first lower fixed comb tooth array located below the first upper movable comb tooth array. The first upper movable comb tooth array and the first lower fixed comb tooth array constitute a right comb tooth capacitor;

[0020] The second driving comb teeth are composed of a second upper movable comb tooth array fixed to the left side of the lower end of the sensitive mass block and a second lower fixed comb tooth array located below the second upper movable comb tooth array. The second upper movable comb tooth array and the second lower fixed comb tooth array constitute a left comb tooth capacitor.

[0021] The first lower fixed comb tooth array and the second lower fixed comb tooth array are respectively fixed to the driving comb tooth fixing anchor points located on the left and right sides of the lower end of the sensitive mass block, and the driving comb tooth fixing anchor points are sputtered with a metal electrode layer.

[0022] 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;

[0023] The first detection comb teeth are composed of a left movable comb tooth array fixed on the right side of the sensitive mass block and a right fixed comb tooth array located on the right side of the left movable comb tooth array, and the left movable comb tooth array and the right fixed comb tooth array constitute a right comb tooth capacitor;

[0024] The second detection comb teeth are composed of a right 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 right movable comb tooth array, and the right movable comb tooth array and the left fixed comb tooth array constitute a left comb tooth capacitor;

[0025] 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.

[0026] 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.

[0027] When a bistable beam experiences negative stiffness, the driving force required is already substantial. Directly connecting straight beams to the two sides of the proof mass significantly increases the driving force required to reach the quasi-zero stiffness range of the MEMS accelerometer, necessitating 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 significantly increased number of drive combs. This increase in combs increases device size and manufacturing costs, while also increasing the mass of the sensitive mass, which is carried by the beam and should not be too large.

[0028] 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:

[0029] 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.

[0030] 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.

[0031] Third, and most importantly, the design method proposed in this invention significantly reduces the required driving force and achieves multiple quasi-zero stiffness intervals, thus widening the device's permissible range of motion compared to a single beam. Theoretical derivation and experimental simulation analysis show that, for a bistable beam with the same horizontal span, the required driving force is only 1 / 4 that of a simple bistable beam structure and 1 / 9 that of a non-series straight beam. This represents a breakthrough in magnitude. Furthermore, with four quasi-zero stiffness intervals, the use of a suspension structure also increases the device's permissible range of motion to approximately four times that of a non-suspension structure.

[0032] 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 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.

[0033] In summary, the present invention provides a multi-interval quasi-zero stiffness MEMS accelerometer based on a suspension-parallel bistable beam-straight beam series design. This design utilizes the mutual compensation mechanism between the negative stiffness of the bistable beam and the local linear positive stiffness of the series straight beam to produce a local quasi-zero stiffness effect. Furthermore, a suspension connection is employed to achieve multi-interval quasi-zero stiffness. 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, paving the way for the development of micromachined quasi-zero stiffness accelerometers. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is an enlarged view of the overall and local details of a multi-interval quasi-zero stiffness MEMS accelerometer based on a suspension parallel bistable beam-straight beam design provided by an embodiment of the present invention;

[0035] 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.

[0036] Figure 3 It is a three-dimensional diagram of a single suspension structure;

[0037] Figure 4 It is the power supply circuit diagram of the present invention;

[0038] Figure 5 Schematic diagram of the structure of a multi-interval quasi-zero stiffness MEMS accelerometer based on a bistable beam-straight beam design provided by an embodiment of the present invention;

[0039] Figure 6 is the force-displacement diagram of a single bistable beam;

[0040] Figure 7 is the force-displacement diagram of a single straight beam;

[0041] Figure 8 is the force-displacement diagram of the bistable beam suspension structure;

[0042] Figure 9 It is a force-displacement relationship diagram of the accelerometer of the present invention.

[0043] In the picture:

[0044] 1-1 Sensitive mass block 4-1 First suspension

[0045] 2-1 First drive comb 4-2 Second suspension

[0046] 2-2 Second drive comb 4-3 Third suspension 3-1 First bistable beam - straight beam 4-4 Fourth suspension

[0047] 3-2 Second bistable beam - straight beam 4-5 Fifth suspension

[0048] 3-3 Third bistable beam - straight beam 4-6 Sixth suspension

[0049] 3-4 Fourth bistable beam - straight beam 5-1 First detection comb

[0050] 3-5 Fifth bistable beam - straight beam 5-2 Second detection comb

[0051] 3-6 Sixth bi-stable beam - straight beam 6-1 First fixed anchor point

[0052] 3-7 Seventh bi-stable beam - straight beam 6-2 Second fixed anchor point

[0053] 3-8 Eighth bi-stable beam - straight beam 6-3 Third fixed anchor point

[0054] 3-9 Ninth bi-stable beam - straight beam 6-4 Fourth fixed anchor point

[0055] 3-10 Tenth bi-stable beam - straight beam 6-5 Fifth fixed anchor point

[0056] 3-11 11th double stable beam - straight beam 6-6 6th fixed anchor point

[0057] 3-12 twelfth bistable beam - straight beam 7-1 first metal electrode layer

[0058] 3-13 Thirteenth Bistable Beam - Straight Beam 7-2 Second Metal Electrode Layer

[0059] 3-14 Fourteenth bistable beam - straight beam 7-3 Third metal electrode layer

[0060] 3-15 Fifteenth bistable beam - straight beam 7-4 Fourth metal electrode layer

[0061] 3-16 Sixteenth bistable beam - straight beam 7-5 Fifth metal electrode layer DETAILED DESCRIPTION

[0062] 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.

[0063] Embodiments of the present invention provide a multi-interval quasi-zero stiffness MEMS accelerometer based on a suspension-parallel bistable beam-straight beam series 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. Furthermore, by combining multiple suspension connections, quasi-zero stiffness in multiple intervals is achieved. Furthermore, the driving force required for the bistable beam itself is significantly reduced, significantly improving the system's sensitivity and expanding the research and application of MEMS quasi-zero stiffness.

[0064] Reference Figure 1 and Figure 5 ,The accelerometer consists of seven modules, namely, the sensitive mass module, the driving comb module, the ,suspension parallel bistable beam-straight beam series module, the suspension module, the ,detection comb module, the fixed anchor module and the metal electrode module.

[0065] The sensitive mass module is the main body, which is composed of a sensitive mass block 1-1 located at the center of the accelerometer. The movement of the sensitive mass block 1-1 is unidirectional, which is determined by the arch direction of the arch beam. The movement direction of the sensitive mass block 1-1 is opposite to the initial arch direction of the arch beam, and it always maintains in-plane movement. The in-plane movement, that is, 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 completely 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.

[0066] The driving comb module includes two parts of the comb structure, namely Figure 5The 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 1 As can be seen, the first drive comb 2-1 comprises two upper and lower comb arrays. The upper comb array is connected to the sensitive mass 1-1 and moves in a manner consistent with that of the sensitive mass 1-1. The lower comb array is fixed to the third anchor point 6-3 located on the lower right side of the sensitive mass 1-1 as a fixed constraint and is immovable. Similarly, the upper drive comb array of the second drive comb 2-2 is fixed to the sensitive mass 1-1 and moves in a manner consistent with that of the sensitive mass 1-1. The lower drive comb array is fixed to the fifth anchor point 6-5 located on the lower left side of the sensitive mass 1-1 and is immovable. To ensure that the movement of the sensitive mass 1-1 conforms to the design, the attractive force generated by the first drive comb 2-1 and the attractive force generated by the second drive comb 2-2 must be consistent in direction and magnitude. To generate attractive force between the comb teeth, a voltage difference must first be generated between the comb teeth. The voltage of the upper 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 first metal electrode layer 7-1 on the first clamping anchor 6-1 located above the sensitive mass. This is because the first clamping anchor 6-1 is interconnected with the beam structure and the sensitive mass. The specific connection method will be explained in detail in the introduction to the suspension parallel bistable beam-straight beam series module. By applying a certain voltage to the first metal electrode layer 7-1 on the first clamping anchor 6-1, the entire main device is charged with a certain voltage. In addition, by applying different voltages to the third metal electrode layer 7-3 on the third clamping anchor 6-3 and the fourth metal electrode layer 7-4 on the fifth clamping anchor 6-5, a voltage difference is generated between the two drive comb arrays in the same drive comb structure, resulting in the same attractive force between the first drive comb 2-1 and the second drive comb 2-2, thereby driving the movement of the sensitive mass 1-1. The sensitive mass block 1-1 is able to move in mid-air and is supported by a beam structure.

[0067] The suspension parallel bistable beam-straight beam series module includes sixteen arch beams and sixteen straight beams. It should be noted that the bistable beams-straight beams 3-1 to 3-16 are referred to as beam structures. The bistable beams in the beam structure 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 connection are shown. Since the thickness of the bistable beam and the straight beam are consistent and the etching depth is consistent, the cross-sections of the two beams are the same rectangle, and the ends of the two beams can be directly aligned and fixed. In order to explain the connection method in detail, Figure 5In the example, the right side of the suspension parallel bistable beam-straight beam series module in the upper half of the accelerometer structure is shown. The left end of the first bistable beam-straight beam 3-1 is fixed to the first suspension 4-1, and its right end is connected to the right side of the first fixed anchor point 6-1. The left end of the second bistable beam-straight beam 3-2 is fixed to the second suspension 4-2, and its right end is connected to the right side of the first suspension 4-1. The left end of the third bistable beam-straight beam 3-3 is fixed to the third suspension 4-3, and its right end is connected to the right side of the second suspension 4-2. The left end of the fourth bistable beam-straight beam 3-4 is fixed to the sensitive straight beam block 1-1, and its right end is connected to the right side of the third suspension 4-3. Through this connection method, the sixteen bistable beams-straight beams are connected one by one to the suspension, fixed anchor points, and sensitive straight beam blocks, respectively, located on the upper and lower sides of the sensitive mass block, and the arch direction of the bistable beams in each bistable beam-straight beam series structure is consistent. The eight pairs of bistable beams and straight beams in series structure support the sensitive mass block 1 - 1 and power the sensitive mass block through the first metal electrode layer 7 - 1 on the first clamping anchor point 6 - 1 .

[0068] The suspension module is Figure 5 There are six suspension structures in total, 4-1 to 4-6, which play the role of connecting different layers of bistable beams and straight beams. The connection method has been clearly described in the above bistable beam and straight beam part, and Figure 3 A three-dimensional schematic diagram of a single suspension structure is given.

[0069] The detection comb module includes Figure 5The first detection comb teeth 5-1 and the second detection comb teeth 5-2 in the figure. 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. 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 5-1 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 5-1, 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 second fixed anchor point 6-2 located on the right side of the sensitive mass block and always remains stationary. The second fixed anchor point 6-2 is sputtered with a second metal electrode layer 7-2. The left comb tooth array and the right comb tooth array form multiple pairs of parallel plates. The change in capacitance between the parallel plates can directly reflect the displacement change of the sensitive mass block 1-1. The second detection comb 5-2 is similarly located on the left side of the sensitive mass block. The right comb array is fixedly connected to the sensitive mass block 1-1 and moves with the movement of the sensitive mass block 1-1. The left comb array is fixedly connected to the sixth fixed anchor point 6-6 located on the left side of the sensitive mass block and remains stationary. The sixth fixed anchor point 6-6 is sputtered with a fifth metal electrode layer 7-5. Before the MEMS accelerometer can operate, it needs to be wired, that is, the metal electrode layers on each fixed anchor point are connected to the corresponding terminal. When the sensitive mass block moves, the capacitance value between the parallel plates of each detection comb module will change, so that a capacitance value change signal representing the displacement of the sensitive mass block 1-1 can be measured between the second metal electrode layer 7-2 and the fifth metal electrode layer 7-5.

[0070] The fixing anchor points and the metal electrode layer have been described in detail in the detailed description of the other modules above, so they will not be described in detail. Figure 4 This is the power supply circuit diagram of the present invention. The working principles of each metal electrode layer have been fully described in the detailed description of other modules above, so they will not be described in detail.

[0071] In summary, the driving force and displacement are explained in detail. Figure 6 is the force-displacement diagram of the bistable beam, Figure 7 is the force-displacement diagram of a straight beam, Figure 8 This is the force-displacement diagram of the suspension structure containing only the bistable beam. Figure 9 This is the force-displacement relationship diagram of the bistable beam-straight beam series suspension structure of the present invention. Figure 9As 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.

[0072] 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 excitation, 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. The designed feedback driving force is applied to the sensitive mass by superimposing the original driving force through the first and second drive combs 2-1 and 2-2 to balance the external acceleration excitation. Therefore, the magnitude of the external acceleration can be represented by the quotient of the feedback driving force and the mass of the sensitive mass 1-1.

[0073] 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 suspension parallel design, characterized in that: It includes a sensitive mass block, a driving comb module, a suspension parallel bistable beam-straight beam series module, and a detection comb module; A suspension parallel bistable beam-straight beam series module is provided above and below the sensitive mass block, respectively. The raised structures located in the middle of the upper and lower sides of the sensitive mass block are connected to the suspension parallel bistable beam-straight beam series modules on that side. The driving comb modules are located at the left and right ends of the lower side of the sensitive mass block, and the detection comb modules are located on the left and right sides of the sensitive mass block. The suspension parallel bistable beam-straight beam series module includes a suspension assembly and a beam structure obtained by connecting a bistable beam and a straight beam in series, wherein the bistable beam is a half-period cosine function structure; the suspension assembly includes a suspension fixed anchor point and a movable suspension, wherein the suspension fixed anchor point is fixed above and below the sensitive mass block, and a metal electrode layer is sputtered on the suspension fixed anchor point; a plurality of parallel movable suspensions are provided between the suspension fixed anchor point and the upper / lower middle protruding structure of the sensitive mass block; the movable suspension closest to the sensitive mass block and the protruding structure of the sensitive mass block, the movable suspension farthest from the sensitive mass block and the suspension fixed anchor point, and two adjacent movable suspensions are all connected by a beam structure.

2. The quasi-zero stiffness MEMS accelerometer based on a suspension parallel design according to claim 1, characterized in that: The movable suspension is composed of a horizontal rod, a first connecting part located at both ends of the horizontal rod and facing the sensitive mass block, and a second connecting part located in the middle of the horizontal rod and facing away from the sensitive mass block. The first connecting part of the movable suspension closest to the sensitive mass block and the protruding structure of the sensitive mass block, the second connecting part of the movable suspension farthest from the sensitive mass block and the two ends of the suspension fixed anchor point, and the first connecting part and the second connecting part of two adjacent movable suspensions are all connected by a beam structure.

3. The quasi-zero stiffness MEMS accelerometer based on suspension parallel design according to claim 2, characterized in that: One end of the bistable beam in the beam structure faces inward, one end of the straight beam in the beam structure faces outward, and the arch directions of the bistable beams in all beam structures are consistent.

4. A quasi-zero stiffness MEMS accelerometer based on a suspension parallel design according to claim 1 or 3, characterized in that: The movement direction of the sensitive mass is opposite to the initial arch direction of the bistable beam in the beam structure.

5. The quasi-zero stiffness MEMS accelerometer based on a suspension parallel design according to claim 1, characterized in that: The thickness of the bistable beam and the straight beam in the beam structure are consistent, and the length ratio is (1-3):

1.

6. The quasi-zero stiffness MEMS accelerometer based on a suspension parallel design according to claim 1, characterized in that: The ratio of the arch height to the arch thickness of the bistable beam is 1.2 to 1.

67.

7. The quasi-zero stiffness MEMS accelerometer based on a suspension parallel design according to claim 1, characterized in that: The lengths of the plurality of movable suspensions arranged in parallel between the suspension fixing anchor point and the upper / lower middle protruding structure of the sensitive mass block decrease in sequence.

8. The quasi-zero stiffness MEMS accelerometer based on a suspension parallel design according to claim 1 or 7, characterized in that: The number of the plurality of movable suspensions arranged in parallel is 3-6.

9. The quasi-zero stiffness MEMS accelerometer based on a suspension parallel 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 left and right sides of the lower end of the sensitive mass block; The first driving comb teeth (2-1) are composed of a first upper movable comb tooth array fixed on the right side of the lower end of the sensitive mass block and a first lower fixed comb tooth array located below the first upper movable comb tooth array, and the first upper movable comb tooth array and the first lower fixed comb tooth array form a right comb tooth capacitor; The second driving comb teeth (2-2) are composed of a second upper movable comb tooth array fixed on the left side of the lower end of the sensitive mass block and a second lower fixed comb tooth array located below the second upper movable comb tooth array, and the second upper movable comb tooth array and the second lower fixed comb tooth array constitute a left comb tooth capacitor; The first lower fixed comb tooth array and the second lower fixed comb tooth array are respectively fixed to the driving comb tooth fixing anchor points located on the left and right sides of the lower end of the sensitive mass block, and the driving comb tooth fixing anchor points are sputtered with a metal electrode layer.

10. The quasi-zero stiffness MEMS accelerometer based on suspension parallel design according to claim 1, characterized in that: The detection comb module comprises a first detection comb (5-1) and a second detection comb (5-2) located on the left and right sides of the sensitive mass block; The first detection comb teeth (5-1) are composed of a left movable comb tooth array fixed on the right side of the sensitive mass block and a right fixed comb tooth array located on the right side of the left movable comb tooth array, and the left movable comb tooth array and the right fixed comb tooth array form a right comb tooth capacitor; The second detection comb teeth (5-2) are composed of a right movable comb tooth array fixed at the left boundary of the sensitive mass block and a left fixed comb tooth array located on the left side of the right movable comb tooth array, and the right movable comb tooth array and the left fixed comb tooth array constitute a left comb tooth 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.

Images