A coupled stiffness perturbed mems modal localization accelerometer

Abstract

The application provides a coupling stiffness disturbance type MEMS modal localization accelerometer, a core sensitive unit adopts a double-tongue resonator parallel arrangement configuration, and a weak coupling resonance system is constructed by means of the difference design of equivalent support stiffness parameters. The outer tongue resonator is directly connected with the sensitive mass block, the inner tongue resonator is fixed by full constraint through the base anchor point, and the two are connected by a parallel plate of electrostatic coupling to form a double-tongue electrostatic weak coupling resonance structure, so that the energy transmission between the resonance units is realized. The application is different from the traditional stiffness or mass disturbance type modal localization sensor in mechanism. When the accelerometer is subjected to the action of external acceleration, the inertial micro displacement is converted into the coupling stiffness change of the weak coupling resonance system, the detection of the resonance unit amplitude ratio of the weak coupling resonance system is realized through the external circuit, the detection of the coupling stiffness disturbance is realized, and finally the high sensitivity detection of the measured acceleration is realized.

Description

Technical Field

[0001] This invention relates to the fields of microelectromechanical systems and microinertial measurement, and particularly to a coupled stiffness perturbation type MEMS modal localization accelerometer. Background Technology

[0002] With the continuous maturation of microelectromechanical systems (MEMS) technology, modal localization sensors based on weakly coupled resonators have rapidly become a research hotspot in the field of inertial sensing due to their "ultra-high sensitivity" advantage. Unlike traditional resonant accelerometers that rely on frequency offset detection, these devices achieve sensing by monitoring the change in the amplitude ratio of the weakly coupled resonant system under disturbance, which theoretically can improve the sensitivity by one to three orders of magnitude.

[0003] However, existing modal localization sensors are typically designed based on mass perturbation or stiffness perturbation, and their mechanical sensitivity is limited by the modal aliasing effect, with a theoretical upper limit that cannot be broken. Mass perturbation type sensors add a sensitive mass block to one of the coupled resonators, using acceleration to change the effective mass of the resonator; stiffness perturbation type sensors directly change the stiffness parameters of the resonator itself by designing an acceleration-sensitive support structure. Although these schemes utilize the modal localization effect, they all face a fundamental theoretical limitation—the modal aliasing effect. When the external perturbation (acceleration) increases, the characteristic modes of the weakly coupled system will interact violently or even exchange, causing the rate of change of the amplitude ratio characterizing the measured value to drop sharply, saturate, or even reverse. This phenomenon strictly limits the maximum achievable mechanical sensitivity and linear operating range of the sensor, becoming a theoretical bottleneck that is difficult to overcome for further improvement of the performance of existing modal localization sensors. Therefore, a new signal variation mode is urgently needed to avoid the modal aliasing effect and fully unleash the ultra-high sensitivity potential of the modal localization principle. Summary of the Invention

[0004] Objective of the Invention: The technical problem to be solved by this invention is to address the shortcomings of existing technologies by providing a coupled stiffness perturbation-based MEMS modal localization accelerometer. This invention utilizes the electrostatic negative stiffness effect to directly convert the micro-displacement changes of the sensitive mass block caused by external acceleration signals into coupled stiffness perturbations of a weakly coupled resonant system, constructing a highly efficient and reliable signal-coupled stiffness conversion topology, thereby significantly improving signal conversion efficiency.

[0005] The accelerometer described in this invention adopts a double-layer structure;

[0006] The dual-layer structure includes a signal conversion layer and a signal output layer;

[0007] The signal conversion layer adopts a silicon micromechanical structure; the signal output layer includes a glass insulating layer and metal signal leads;

[0008] The silicon micromechanical structure is fixed to the upper surface of the glass insulating layer by silicon-glass bonding technology. The anchor points of the silicon micromechanical structure correspond to the positions of the metal signal leads, thereby realizing the input and output control of electrical signals.

[0009] The silicon micromechanical structure includes a sensitive mass block, a double tuning fork resonator, and a directional elastic support structure. The directional elastic support structure includes a first directional elastic support structure, a second directional elastic support structure, a third directional elastic support structure, and a fourth directional elastic support structure.

[0010] The silicon micromechanical structure is used to convert external acceleration signals into electrostatic coupling stiffness changes of a weakly coupled resonant system through the inertial micro-displacement changes of a sensitive mass block, and finally outputs an electrical signal that can be directly measured.

[0011] The dual tuning fork resonators, as the core sensing unit of the accelerometer, are arranged in parallel. The dual tuning fork resonators include an outer tuning fork resonator and an inner tuning fork resonator.

[0012] The double tuning fork resonator is arranged at the center of the sensitive mass block, and the resonant beams of the outer and inner tuning fork resonators are symmetrical about the center of the sensitive mass block, forming a differential structure.

[0013] The outer tuning fork resonator is directly connected to the sensitive mass block; the inner tuning fork resonator is fully constrained and fixed through the base anchor point; the outer tuning fork resonator and the inner tuning fork resonator have equivalent support stiffness parameter differences, forming an off-tuned weakly coupled resonant system;

[0014] The outer tuning fork resonator and the inner tuning fork resonator are connected by an electrostatic coupling parallel plate to form a double tuning fork electrostatic weak coupling resonant structure, so as to realize energy transfer between the resonant units.

[0015] When the accelerometer is subjected to external acceleration, the inertial micro-displacement generated by the sensitive mass block causes a change in the spacing of the electrostatic coupling parallel plates, which in turn leads to a change in the coupling stiffness of the weakly coupled resonant system.

[0016] The accelerometer detects coupling stiffness disturbances by measuring the amplitude ratio of the outer and inner tuning fork resonators in the weakly coupled resonant system, ultimately achieving high-sensitivity detection of external acceleration.

[0017] The first directional elastic support structure, the second directional elastic support structure, the third directional elastic support structure, and the fourth directional elastic support structure are respectively arranged at the upper right, lower right, lower left, and upper left positions of the sensitive mass block, and are respectively connected to the sensitive mass block through the first directional elastic beam, the second directional elastic beam, the third directional elastic beam, and the fourth directional elastic beam.

[0018] The dual tuning fork resonator is used to convert micro-displacement signals into capacitance signals that can be measured by the matching circuit.

[0019] The external tuning fork resonator includes an external tuning fork resonator beam, a first electrostatic coupling parallel plate, a second electrostatic coupling parallel plate, a first driving capacitor comb, a second driving capacitor comb, a third driving capacitor comb, a fourth driving capacitor comb, a first detection capacitor comb, and a second detection capacitor comb.

[0020] The inner tuning fork resonator includes an inner tuning fork resonator beam, a third electrostatic coupling parallel plate, a fourth electrostatic coupling parallel plate, a fifth driving capacitor comb tooth, a sixth driving capacitor comb tooth, a third detection capacitor comb tooth, and a fourth detection capacitor comb tooth.

[0021] The support stiffness of the inner tuning fork resonator is: The support stiffness of the external tuning fork resonator is , ;

[0022] The inner side of the outer tuning fork resonator of the double tuning fork resonator is connected to a first electrostatic coupling parallel plate and a second electrostatic coupling parallel plate.

[0023] The inner tuning fork resonator beam is connected to a third electrostatic coupling parallel plate and a fourth electrostatic coupling parallel plate on its outer side.

[0024] The first electrostatic coupling parallel plate and the third electrostatic coupling parallel plate are at an initial spacing The opposing parallel plates form the first electrostatic coupling parallel plate group;

[0025] The second and fourth electrostatic coupling parallel plates are spaced at an initial distance. The opposing parallel plates form a second electrostatic coupling plate group;

[0026] The first and second electrostatic coupling parallel plate groups are both arranged horizontally; they are symmetrically distributed, and the sensitive mass block drives the external tuning fork resonator to move through micro-displacement, differentially changing the spacing d to achieve common-mode error suppression and altering the coupling stiffness through the electrostatic negative stiffness effect. .

[0027] The coupling stiffness The relationship between acceleration and acceleration is expressed as follows:

[0028] ,

[0029] in, The displacements of the first and second electrostatically coupled parallel plates caused by acceleration are represented by A; A is the overlap area of ​​the first and third electrostatically coupled parallel plates and the second and fourth electrostatically coupled parallel plates. The difference in bias voltage applied between the first and third electrostatic coupling parallel plates and the second and fourth electrostatic coupling parallel plates; is the dielectric constant.

[0030] The outer tuning fork resonator is connected to an inner comb tooth support cantilever and an outer comb tooth support cantilever on the outside of the outer tuning fork resonator beam; the inner tuning fork resonator beam is connected to a comb tooth support cantilever on the inside.

[0031] The inner comb support arm has driving capacitor comb teeth arranged on both sides; the outer comb support arm has detection capacitor comb teeth arranged on the outer side.

[0032] The comb support cantilever is provided with driving capacitor comb teeth and detection capacitor comb teeth on both sides respectively.

[0033] The first driving capacitor comb teeth, the second driving capacitor comb teeth, the third driving capacitor comb teeth and the fourth driving capacitor comb teeth are arranged in an alternating manner with the driving capacitor comb teeth on both sides of the inner comb tooth support cantilever to form the first driving comb tooth group.

[0034] The first detection capacitor comb teeth, the second detection capacitor comb teeth, and the detection capacitor comb teeth arranged on the outer side of the outer comb tooth support cantilever form the first detection comb tooth group by interleaving and interlocking.

[0035] The fifth and sixth driving capacitor comb teeth, along with the driving capacitor comb teeth arranged on the side of the comb tooth support cantilever away from the inner tuning fork resonant beam, interlock to form the second driving comb tooth group; the third and fourth detection capacitor comb teeth, along with the detection capacitor comb teeth arranged on the side of the comb tooth support cantilever near the inner tuning fork resonant beam, interlock to form the second detection comb tooth group.

[0036] The first directional elastic support structure, the second directional elastic support structure, the third directional elastic support structure, and the fourth directional elastic support structure have the same structure.

[0037] The first directional elastic support structure consists of a first support anchor point and a first directional elastic beam, which is used to ensure the good performance and stability of the accelerometer.

[0038] One end of the first directional elastic beam is connected to the first support anchor point, and the other end is connected to the sensitive mass block.

[0039] The signal output layer further includes: a first electrode, a second electrode, a third electrode, a fourth electrode, a first driving signal lead-out electrode, a second driving signal lead-out electrode, a third driving signal lead-out electrode, and a fourth driving signal lead-out electrode;

[0040] The first electrode, the second electrode, the third electrode, and the fourth electrode are bonded to the first driving capacitor comb teeth, the second driving capacitor comb teeth, the third driving capacitor comb teeth, and the fourth driving capacitor comb teeth, respectively, and are connected to the first driving signal lead-out electrode, the second driving signal lead-out electrode, the third driving signal lead-out electrode, and the fourth driving signal lead-out electrode, respectively, through leads.

[0041] The signal output layer further includes: a fifth electrode, a sixth electrode, a first detection signal lead-out electrode, and a second detection signal lead-out electrode; wherein the fifth electrode and the sixth electrode are respectively bonded to the first detection capacitor comb teeth and the second detection capacitor comb teeth, and are respectively connected to the first detection signal lead-out electrode and the second detection signal lead-out electrode through leads.

[0042] The signal output layer further includes: a seventh electrode, an eighth electrode, a fifth driving signal lead-out electrode, and a sixth driving signal lead-out electrode; wherein the seventh electrode and the eighth electrode are respectively bonded to the fifth driving capacitor comb teeth and the sixth driving capacitor comb teeth, and are respectively connected to the fifth driving signal lead-out electrode and the sixth driving signal lead-out electrode through leads.

[0043] The signal output layer further includes: a ninth electrode, a tenth electrode, an eleventh electrode, a twelfth electrode, a thirteenth electrode, a third detection signal lead-out electrode, a fourth detection signal lead-out electrode, a first electrostatic common lead-out electrode, and a common terminal lead-out electrode; wherein the ninth electrode and the tenth electrode are bonded to the third detection capacitor comb teeth and the fourth detection capacitor comb teeth, respectively, and are connected to the third detection signal lead-out electrode and the fourth detection signal lead-out electrode through leads;

[0044] The eleventh and twelfth electrodes are bonded to the inner tuning fork resonator beam and connected to the first electrostatic common lead-out electrode via leads;

[0045] The thirteenth electrode is bonded to the external tuning fork resonator beam and connected to the common terminal lead-out electrode via a lead wire.

[0046] Compared with the prior art, the present invention has the following advantages: (1) The present invention designs a signal transformation mechanism of coupling stiffness disturbance, and realizes the overall design of the structure based on the transformation mechanism of "external disturbance-micro displacement change-coupling stiffness disturbance", breaking through the theoretical upper limit of mechanical sensitivity of traditional modal localization sensor.

[0047] (2) A differential electrostatic coupling parallel plate is used as the core sensitive element. Based on the principle of electrostatic negative stiffness, the efficient conversion of acceleration and coupling stiffness is realized.

[0048] (3) By designing the difference in equivalent support stiffness parameters, the double tuning fork resonator forms an offset weakly coupled resonant system, which locks the system in the anti-phase working mode, avoids the influence of mode aliasing on sensitivity, and greatly suppresses the energy dissipation of the resonator.

[0049] (4) The dual tuning fork resonant beam integrates the drive / detection comb and electrostatic coupling plate to realize the three conversions of micro-displacement-capacitance-stiffness at the center of the mass block; the silicon-glass bonding stack allows for vertical signal transmission, thus constructing an accelerometer with high space utilization and signal conversion efficiency. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the overall mechanical structure of the present invention.

[0051] Figure 2 This is a schematic diagram of the silicon micromechanical structure of the present invention.

[0052] Figure 3 This is a schematic diagram of the double tuning fork resonator structure of the present invention.

[0053] Figure 4 This is a schematic diagram of the directional elastic support structure of the present invention.

[0054] Figure 5 This is a schematic diagram of the glass insulating layer and signal lead wires of the present invention.

[0055] Figure 6 This is a graph showing the acceleration-amplitude ratio response characteristics of the present invention.

[0056] Explanation of reference numerals in the attached figures: 1: Sensitive mass block; 2: Double tuning fork resonator; 3: Directional elastic support structure; 4: Glass insulating layer; 2-1: Outer tuning fork resonator; 2-2: Inner tuning fork resonator;

[0057] 2-1-1: External tuning fork resonant beam; 2-1-2: First driving capacitor comb teeth; 2-1-3: Second driving capacitor comb teeth; 2-1-4: Third driving capacitor comb teeth; 2-1-5: Fourth driving capacitor comb teeth; 2-1-6: First detection capacitor comb teeth; 2-1-7: Second detection capacitor comb teeth; 2-1-8: First electrostatic coupling parallel plate; 2-1-9: Second electrostatic coupling parallel plate; 2-2-7: Third electrostatic coupling parallel plate; 2-2-6: Fourth electrostatic coupling parallel plate; 2-1-10: Inner comb tooth supporting cantilever; 2-1-11: Outer comb tooth supporting cantilever; 2-2-8: Comb tooth supporting cantilever;

[0058] 2-2-1: Inner tuning fork resonant beam; 2-2-2: Fifth driving capacitor comb tooth; 2-2-3: Sixth driving capacitor comb tooth; 2-2-4: Third detection capacitor comb tooth; 2-2-5: Fourth detection capacitor comb tooth;

[0059] 3-1: First-direction elastic support structure; 3-2: Second-direction elastic support structure; 3-3: Third-direction elastic support structure; 3-4: Fourth-direction elastic support structure;

[0060] 3-1-1: First support anchor point; 3-2-1: Second support anchor point; 3-3-1: Third support anchor point; 3-4-1: Fourth support anchor point; 3-1-2: Elastic beam in the first direction; 3-2-2: Elastic beam in the second direction; 3-3-2: Elastic beam in the third direction; 3-4-2: Elastic beam in the fourth direction;

[0061] 5-1-1: First electrode; 5-1-2: Second electrode; 5-1-3: Third electrode; 5-1-4: Fourth electrode; 5-1-5: Fifth electrode; 5-1-6: Sixth electrode; 5-2-1: Seventh electrode; 5-2-2: Eighth electrode; 5-2-3: Ninth electrode; 5-2-4: Tenth electrode; 5-5-1: Eleventh electrode; 5-5-2: Twelfth electrode; 5-5-3: Thirteenth electrode;

[0062] 5-3-1: First drive signal lead-out electrode; 5-3-2: Second drive signal lead-out electrode; 5-3-3: Third drive signal lead-out electrode; 5-3-4: Fourth drive signal lead-out electrode; 5-4-1: Fifth drive signal lead-out electrode; 5-4-2: Sixth drive signal lead-out electrode; 5-3-5: First detection signal lead-out electrode; 5-3-6: Second detection signal lead-out electrode; 5-4-3: Third detection signal lead-out electrode; 5-4-4: Fourth detection signal lead-out electrode;

[0063] 5-6-1: First electrostatic common lead-out electrode; 5-6-2: Common terminal lead-out electrode. Detailed Implementation

[0064] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0065] like Figure 1 As shown, this embodiment of the invention provides a coupled stiffness perturbation type MEMS modal localization accelerometer. The accelerometer adopts a two-layer structure, which includes a signal conversion layer and a signal output layer.

[0066] The signal conversion layer adopts a silicon micromechanical structure; the signal output layer includes a glass insulating layer 4 and metal signal leads;

[0067] The silicon micromechanical structure is fixed to the upper surface of the glass insulating layer 4 by silicon-glass bonding technology. The anchor points of the silicon micromechanical structure correspond to the positions of the metal signal leads, thereby realizing the input and output control of electrical signals.

[0068] like Figure 2 As shown, the silicon micromechanical structure includes a sensitive mass block 1, a double tuning fork resonator 2, and a directional elastic support structure 3. The directional elastic support structure 3 includes a first directional elastic support structure 3-1, a second directional elastic support structure 3-2, a third directional elastic support structure 3-3, and a fourth directional elastic support structure 3-4. It is used to convert the external acceleration signal into the electrostatic coupling stiffness change of the weakly coupled resonant system through the inertial micro-displacement change of the sensitive mass block 1, and finally output an electrical signal that can be directly measured.

[0069] The double tuning fork resonator 2 is arranged at the center of the sensitive mass block 1. The inner tuning fork resonator 2-2 is fully constrained and fixed by the base anchor point, and the outer tuning fork resonator 2-1 is connected to the sensitive mass block 1. The difference in the support stiffness of the two forms an offset weakly coupled resonant system. The resonant beams of the inner and outer tuning fork resonators are symmetrical about the center of the sensitive mass block 1, forming a differential structure.

[0070] The first directional elastic support structure 3-1, the second directional elastic support structure 3-2, the third directional elastic support structure 3-3, and the fourth directional elastic support structure 3-4 are respectively arranged at the upper right, lower right, lower left, and upper left positions of the sensitive mass block 1. One end of the directional elastic support structure 3 is connected to the sensitive mass block 1 through the first directional elastic beam 3-1-2, the second directional elastic beam 3-2-2, the third directional elastic beam 3-3-2, and the fourth directional elastic beam 3-4-2. The other end is fixed to the glass insulating layer 4 through the first support anchor point 3-1-1, the second support anchor point 3-2-1, the third support anchor point 3-3-1, and the fourth support anchor point 3-4-1, so that the sensitive mass block 1 is uniformly supported, forming a suspended mass system for sensing acceleration in the horizontal plane.

[0071] like Figure 3 As shown, the double tuning fork resonator 2 includes an outer tuning fork resonator 2-1 and an inner tuning fork resonator 2-2, which are used to convert micro-displacement signals into capacitance signals that can be measured by the matching circuit.

[0072] The external tuning fork resonator 2-1 includes an external tuning fork resonator beam 2-1-1, a first electrostatic coupling parallel plate 2-1-8, a second electrostatic coupling parallel plate 2-1-9, a first driving capacitor comb tooth 2-1-2, a second driving capacitor comb tooth 2-1-3, a third driving capacitor comb tooth 2-1-4, a fourth driving capacitor comb tooth 2-1-5, a first detection capacitor comb tooth 2-1-6, and a second detection capacitor comb tooth 2-1-7.

[0073] The inner tuning fork resonator 2-2 includes an inner tuning fork resonator beam 2-2-1, a third electrostatic coupling parallel plate 2-2-7, a fourth electrostatic coupling parallel plate 2-2-6, a fifth driving capacitor comb tooth 2-2-2, a sixth driving capacitor comb tooth 2-2-3, a third detection capacitor comb tooth 2-2-4, and a fourth detection capacitor comb tooth 2-2-5.

[0074] The inner tuning fork resonator 2-2 is fully constrained and fixed by the base anchor point, supporting stiffness. High; the external tuning fork resonator 2-1 is connected to the sensitive mass block 1, supporting stiffness. Lower ( The difference in stiffness between the two components forms a misaligned, weakly coupled resonant system, locking in the inverse operating mode, which can effectively suppress energy dissipation and improve the system's quality factor; the stiffness difference between the two components is perturbed by mechanical stiffness. express:

[0075] (1),

[0076] The inner side of the outer tuning fork resonator 2, 2-1-1, is connected to a first electrostatic coupling parallel plate 2-1-8 and a second electrostatic coupling parallel plate 2-1-9; the outer side of the inner tuning fork resonator 2, 2-2-1, is connected to a third electrostatic coupling parallel plate 2-2-7 and a fourth electrostatic coupling parallel plate 2-2-6. The first electrostatic coupling parallel plate 2-1-8 and the third electrostatic coupling parallel plate 2-2-7 are spaced at an initial interval. The first electrostatic coupling parallel plate group is formed by opposing arrangements, and the second electrostatic coupling parallel plate 2-1-9 and the fourth electrostatic coupling parallel plate 2-2-6 are arranged at an initial spacing. A second electrostatic coupling parallel plate group is formed by opposing arrangements, with all parallel plate groups arranged horizontally. The first and second electrostatic coupling parallel plate groups are symmetrically distributed. The sensitive mass block 1's micro-displacement drives the external tuning fork resonator 2-1 to move. The differential change in the distance d between the two parallel plate groups achieves common-mode error suppression and alters the coupling stiffness through the electrostatic negative stiffness effect. ;

[0077] Coupling stiffness The relationship between acceleration and acceleration is expressed as follows:

[0078] (2),

[0079] in, The expression represents the micro-displacement of the first electrostatic coupling parallel plate 2-1-8 and the second electrostatic coupling parallel plate 2-1-9 caused by acceleration; A is the overlapping area of ​​the first, third, second, and fourth electrostatic coupling parallel plates. The difference in bias voltage applied between the first electrostatic coupling parallel plate, the third electrostatic coupling parallel plate, the second electrostatic coupling parallel plate, and the fourth electrostatic coupling parallel plate; is the dielectric constant.

[0080] Micro-displacement of electrostatically coupled parallel plates caused by acceleration The expression is:

[0081] (3),

[0082] in, The gain represents the conversion gain between micro-displacement and acceleration, which is negatively correlated with the stiffness of the elastic beam in the elastically supported structure and positively correlated with the equivalent stiffness of the mass block. The acceleration is the input.

[0083] The outer tuning fork resonator 2 is connected to an inner comb tooth support cantilever 2-1-10 and an outer comb tooth support cantilever 2-1-11 on the outside; the inner tuning fork resonator 2 is connected to a comb tooth support cantilever 2-2-8 on the inside.

[0084] The inner comb support cantilever 2-1-10 on the outer side of the outer tuning fork resonator 2-1-1 is provided with driving capacitor comb teeth on both sides; the outer comb support cantilever 2-1-11 is provided with detection capacitor comb teeth on the outer side; the comb support cantilever 2-2-8 on the inner side of the inner tuning fork resonator 2-2-1 is provided with driving capacitor comb teeth and detection capacitor comb teeth on both sides respectively.

[0085] The first driving capacitor comb teeth 2-1-2, the second driving capacitor comb teeth 2-1-3, the third driving capacitor comb teeth 2-1-4, and the fourth driving capacitor comb teeth 2-1-5 are arranged with the driving capacitor comb teeth on both sides of the inner comb tooth support cantilever 2-1-10 to form a first driving comb tooth group; the fifth driving capacitor comb teeth 2-2-2, the sixth driving capacitor comb teeth 2-2-3 are arranged with the driving capacitor comb teeth on the side of the comb tooth support cantilever 2-2-8 away from the inner tuning fork resonator 2-2-1 to form a second driving comb tooth group.

[0086] The first detection capacitor comb teeth 2-1-6, the second detection capacitor comb teeth 2-1-7, and the detection capacitor comb teeth arranged on the outer side of the outer comb tooth support cantilever 2-1-11 interlock to form a first detection comb tooth group; the third detection capacitor comb teeth 2-2-4 and the fourth detection capacitor comb teeth 2-2-5 and the detection capacitor comb teeth arranged on the comb tooth support cantilever 2-2-8 near the inner tuning fork resonator beam 2-2-1 interlock to form a second detection comb tooth group. A positive-phase drive signal is applied to the first driving capacitor comb teeth 2-1-2 and the third driving capacitor comb teeth 2-1-4, and an anti-phase drive signal is applied to the second driving capacitor comb teeth 2-1-3 and the fourth driving capacitor comb teeth 2-1-5; this ensures that the outer tuning fork resonator 2-1 maintains its natural frequency vibration even when the sensitive mass block 1 drives a micro-displacement.

[0087] like Figure 4 As shown, the first directional elastic support structure 3-1, the second directional elastic support structure 3-2, the third directional elastic support structure 3-3, and the fourth directional elastic support structure 3-4 have identical structures. The first directional elastic support structure 3-1 consists of a first support anchor point 3-1-1 and a first directional elastic beam 3-1-2; the second directional elastic support structure 3-2 consists of a second support anchor point 3-2-1 and a second directional elastic beam 3-2-2; the third directional elastic support structure 3-3 consists of a third support anchor point 3-3-1 and a third directional elastic beam 3-3-2; and the fourth directional elastic support structure 3-4 consists of a fourth support anchor point 3-4-1 and a fourth directional elastic beam 3-4-2. Specifically, taking the first directional elastic support structure 3-1 as an example, one end of the first directional elastic beam 3-1-2 is connected to the first support anchor point 3-1-1, and the other end is connected to the sensitive mass block 1, to ensure good performance and stability of the accelerometer.

[0088] The electrode and lead distribution on the surface of the glass insulating layer 4 in this invention is as follows: Figure 5 As shown. The signal output layer further includes: a first electrode 5-1-1, a second electrode 5-1-2, a third electrode 5-1-3, a fourth electrode 5-1-4, a first drive signal output electrode 5-3-1, a second drive signal output electrode 5-3-2, a third drive signal output electrode 5-3-3, and a fourth drive signal output electrode 5-3-4;

[0089] The first electrode 5-1-1, the second electrode 5-1-2, the third electrode 5-1-3, and the fourth electrode 5-1-4 are respectively bonded to the first driving capacitor comb tooth 2-1-2, the second driving capacitor comb tooth 2-1-3, the third driving capacitor comb tooth 2-1-4, and the fourth driving capacitor comb tooth 2-1-5, and are respectively connected to the first driving signal output electrode 5-3-1, the second driving signal output electrode 5-3-2, the third driving signal output electrode 5-3-3, and the fourth driving signal output electrode 5-3-4 through leads.

[0090] The signal output layer further includes: a fifth electrode 5-1-5, a sixth electrode 5-1-6, a first detection signal lead-out electrode 5-3-5, and a second detection signal lead-out electrode 5-3-6; wherein the fifth electrode 5-1-5 and the sixth electrode 5-1-6 are respectively bonded to the first detection capacitor comb tooth 2-1-6 and the second detection capacitor comb tooth 2-1-7, and are respectively connected to the first detection signal lead-out electrode 5-3-5 and the second detection signal lead-out electrode 5-3-6 through leads.

[0091] The signal output layer further includes: a seventh electrode 5-2-1, an eighth electrode 5-2-2, a fifth driving signal lead-out electrode 5-4-1, and a sixth driving signal lead-out electrode 5-4-2; wherein the seventh electrode 5-2-1 and the eighth electrode 5-2-2 are respectively bonded to the fifth driving capacitor comb teeth 2-2-2 and the sixth driving capacitor comb teeth 2-2-3, and are respectively connected to the fifth driving signal lead-out electrode 5-4-1 and the sixth driving signal lead-out electrode 5-4-2 through leads.

[0092] The signal output layer further includes: a ninth electrode 5-2-3, a tenth electrode 5-2-4, an eleventh electrode 5-5-1, a twelfth electrode 5-5-2, a thirteenth electrode 5-5-3, a third detection signal lead-out electrode 5-4-3, a fourth detection signal lead-out electrode 5-4-4, a first electrostatic common lead-out electrode 5-6-1, and a common terminal lead-out electrode 5-6-2; wherein the ninth electrode 5-2-3 and the tenth electrode 5-2-4 are respectively bonded to the third detection capacitor comb teeth 2-2-4 and the fourth detection capacitor comb teeth 2-2-5, and are connected to the third detection signal lead-out electrode 5-4-3 and the fourth detection signal lead-out electrode 5-4-4 through leads;

[0093] The eleventh electrode 5-5-1 and the twelfth electrode 5-5-2 are bonded to the inner tuning fork resonator beam 2-2-1 and connected to the first electrostatic common lead-out electrode 5-6-1 through a lead wire;

[0094] The thirteenth electrode 5-5-3 is bonded to the external tuning fork resonator beam 2-1-1 and connected to the common terminal lead-out electrode 5-6-2 via a lead wire.

[0095] This invention employs a parallel arrangement of two tuning fork resonators. The outer tuning fork resonator is directly connected to the sensitive mass block, while the inner tuning fork resonator is fully constrained and fixed via a base anchor point. The two are stiffly coupled via electrostatic coupling parallel plates. When the accelerometer is subjected to external acceleration, the slight displacement of the sensitive mass block drives the outer tuning fork resonator, changing the spacing *d* between the electrostatic coupling parallel plates. Based on the electrostatic negative stiffness effect, this slight displacement change is directly converted into a coupling stiffness disturbance in the weakly coupled resonant system, ultimately resulting in a difference in the vibration amplitude of the two tuning fork resonators. By measuring the change in the ratio of the vibration amplitudes of the two tuning fork resonators, the magnitude of the acceleration to be measured can be deduced. The expression for the ratio of the vibration amplitudes of the two tuning fork resonators is:

[0096] (4),

[0097] in, This refers to the mechanical stiffness disturbance of the inner and outer tuning fork resonator beams. This refers to the coupling stiffness.

[0098] When an AC driving voltage is applied to the driving capacitor comb teeth of the double tuning fork resonator, the inner and outer tuning fork resonator beams will undergo forced vibration. Utilizing the significant stiffness difference between the inner tuning fork resonator and the outer tuning fork resonator connected to the mass block, the weakly coupled resonant system can operate stably in a low-dissipation, anti-phase vibration mode, effectively suppressing energy dissipation and improving the system's quality factor. Subsequently, the output signal is captured by detecting the comb teeth group. This signal undergoes capacitor-to-voltage conversion and is precisely locked and tracked by a closed-loop phase-locked circuit to the resonant frequency of this anti-phase mode.

[0099] In this embodiment, the key structural parameters of the core sensitive unit, the double tuning fork resonator, are set as follows:

[0100] 1. The inner tuning fork resonator beam has a length of 1712 μm and a width of 10 μm, with an equivalent support stiffness of [missing value]. ;

[0101] 2. The external tuning fork resonator beam has a length of 1722 μm and a width of 10 μm, with an equivalent support stiffness of [missing value]. ;

[0102] 3. The length of the first, second, third, and fourth electrostatic coupling parallel plates is 1712 μm, the height is 80 μm, and the overlap area is A = 136,960 μm².

[0103] 4. The difference in bias voltage applied between the electrostatic coupling parallel plates =60V;

[0104] 5. Micro-displacement-acceleration conversion gain =0.33g / μm;

[0105] Based on the above structural parameters, according to the principle of the present invention, by performing a Taylor expansion on the amplitude ratio equation (4) and adjusting the acceleration... Taking the derivative, the theoretical sensitivity of the accelerometer in this embodiment can be obtained as the formula:

[0106] = (5),

[0107] Substituting the structural parameters of this embodiment into equation (5) yields the theoretical sensitivity as follows: / g, verified by prototype testing, under standard temperature and pressure conditions, such as Figure 6 As shown, the sensitivity value is The value of / g is in good agreement with the theoretical value, and the slight difference is mainly due to deviations in the microfabrication process. The sensitivity of the accelerometer of this invention is significantly higher than that of traditional resonant accelerometers.

[0108] Meanwhile, the structural parameters of this embodiment satisfy the minimum coupling stiffness condition for avoiding modal aliasing effects: ,

[0109] Where k is the equivalent stiffness of the resonator (which can be taken as...). and (average) This is the system quality factor.

[0110] This invention provides a coupled stiffness perturbation-based MEMS modal localization accelerometer. Many methods and approaches exist for implementing this technical solution; the above description is merely a preferred embodiment of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.

Claims

1. A coupled stiffness perturbation-type MEMS modal localization accelerometer, characterized in that, The accelerometer adopts a double-layer structure; The dual-layer structure includes a signal conversion layer and a signal output layer; The signal conversion layer adopts a silicon micromechanical structure; the signal output layer includes a glass insulating layer (4) and metal signal leads; The silicon micromechanical structure is fixed to the upper surface of the glass insulating layer (4) by silicon-glass bonding technology. The anchor point of the silicon micromechanical structure corresponds to the position of the metal signal lead, thereby realizing the input and output control of electrical signals. The silicon micromechanical structure includes a sensitive mass block (1), a double tuning fork resonator (2), and a directional elastic support structure (3). The directional elastic support structure (3) includes a first directional elastic support structure (3-1), a second directional elastic support structure (3-2), a third directional elastic support structure (3-3), and a fourth directional elastic support structure (3-4). The silicon micromechanical structure is used to convert the external acceleration signal into the electrostatic coupling stiffness change of the weakly coupled resonant system through the inertial micro-displacement change of the sensitive mass block (1), and finally outputs an electrical signal that can be directly measured. The double tuning fork resonator (2) is the core sensitive unit of the accelerometer and is arranged in parallel. The double tuning fork resonator (2) includes an outer tuning fork resonator (2-1) and an inner tuning fork resonator (2-2). The double tuning fork resonator (2) is arranged at the center of the sensitive mass block (1). The resonant beams of the outer tuning fork resonator (2-1) and the inner tuning fork resonator (2-2) are symmetrical about the center of the sensitive mass block (1), forming a differential structure. The outer tuning fork resonator (2-1) is directly connected to the sensitive mass block (1); the inner tuning fork resonator (2-2) is fully constrained and fixed through the base anchor point; the outer tuning fork resonator (2-1) and the inner tuning fork resonator (2-2) have equivalent support stiffness parameter differences, forming an off-tuned weakly coupled resonant system; The outer tuning fork resonator (2-1) and the inner tuning fork resonator (2-2) are connected by an electrostatic coupling parallel plate to form a double tuning fork electrostatic weak coupling resonant structure, so as to realize energy transfer between the resonant units; When the accelerometer is subjected to external acceleration, the inertial micro-displacement generated by the sensitive mass block (1) causes the spacing of the electrostatic coupling parallel plates to change, which in turn leads to the change of the coupling stiffness of the weakly coupled resonant system. The accelerometer detects coupling stiffness disturbances by measuring the amplitude ratio of the outer tuning fork resonator (2-1) and the inner tuning fork resonator (2-2) in the weakly coupled resonant system, and ultimately achieves high-sensitivity detection of external acceleration. The double tuning fork resonator (2) is used to convert micro-displacement signals into capacitance signals that can be measured by the matching circuit. The external tuning fork resonator (2-1) includes an external tuning fork resonator beam (2-1-1), a first electrostatic coupling parallel plate (2-1-8), a second electrostatic coupling parallel plate (2-1-9), a first driving capacitor comb tooth (2-1-2), a second driving capacitor comb tooth (2-1-3), a third driving capacitor comb tooth (2-1-4), a fourth driving capacitor comb tooth (2-1-5), a first detection capacitor comb tooth (2-1-6), and a second detection capacitor comb tooth (2-1-7). The inner tuning fork resonator (2-2) includes an inner tuning fork resonator beam (2-2-1), a third electrostatic coupling parallel plate (2-2-7), a fourth electrostatic coupling parallel plate (2-2-6), a fifth driving capacitor comb tooth (2-2-2), a sixth driving capacitor comb tooth (2-2-3), a third detection capacitor comb tooth (2-2-4), and a fourth detection capacitor comb tooth (2-2-5). The supporting stiffness of the inner tuning fork resonator (2-2) is k1, and the supporting stiffness of the outer tuning fork resonator (2-1) is k2, where k1>k2. The inner side of the outer tuning fork resonator (2) of the double tuning fork resonator (2) is connected to a first electrostatic coupling parallel plate (2-1-8) and a second electrostatic coupling parallel plate (2-1-9). The inner tuning fork resonator beam (2-2-1) is connected to a third electrostatic coupling parallel plate (2-2-7) and a fourth electrostatic coupling parallel plate (2-2-6) on its outer side. The first electrostatic coupling parallel plate (2-1-8) and the third electrostatic coupling parallel plate (2-2-7) are at an initial spacing The opposing parallel plates form the first electrostatic coupling parallel plate group; The second electrostatic coupling parallel plate (2-1-9) and the fourth electrostatic coupling parallel plate (2-2-6) are at an initial spacing The opposing parallel plates form a second electrostatic coupling plate group; The first electrostatic coupling parallel plate group and the second electrostatic coupling parallel plate group are both arranged in a horizontal direction. The first electrostatic coupling parallel plate group and the second electrostatic coupling parallel plate group are symmetrically distributed. The sensitive mass block (1) drives the external tuning fork resonator (2-1) to move through micro-displacement, differentially changing the spacing d to achieve common-mode error suppression and changing the coupling stiffness through the electrostatic negative stiffness effect. .

2. The coupled stiffness perturbation type MEMS modal localization accelerometer according to claim 1, characterized in that, The first directional elastic support structure (3-1), the second directional elastic support structure (3-2), the third directional elastic support structure (3-3), and the fourth directional elastic support structure (3-4) are respectively arranged at the upper right, lower right, lower left, and upper left positions of the sensitive mass block (1), and are respectively connected to the sensitive mass block (1) through the first directional elastic beam (3-1-2), the second directional elastic beam (3-2-2), the third directional elastic beam (3-3-2), and the fourth directional elastic beam (3-4-2).

3. The coupled stiffness perturbation type MEMS modal localization accelerometer according to claim 2, characterized in that, The coupling stiffness The relationship between acceleration and acceleration is expressed as follows: ， in, This represents the micro-displacement of the first electrostatically coupled parallel plate (2-1-8) and the second electrostatically coupled parallel plate (2-1-9) caused by acceleration; The overlapping area of ​​the first and third electrostatic coupling parallel plates and the second and fourth electrostatic coupling parallel plates. The difference in bias voltage applied between the first and third electrostatic coupling parallel plates and the second and fourth electrostatic coupling parallel plates; is the dielectric constant.

4. The coupled stiffness perturbation type MEMS modal localization accelerometer according to claim 3, characterized in that, The outer tuning fork resonator (2) has an inner comb tooth support cantilever (2-1-10) and an outer comb tooth support cantilever (2-1-11) connected to the outer tuning fork resonator beam (2-1-1); the inner tuning fork resonator beam (2-2-1) has a comb tooth support cantilever (2-2-8) connected to the inner side. The inner comb tooth support cantilever (2-1-10) has driving capacitor comb teeth arranged on both sides; the outer comb tooth support cantilever (2-1-11) has detection capacitor comb teeth arranged on the outer side. The comb support cantilever (2-2-8) has driving capacitor comb teeth and detection capacitor comb teeth arranged on both sides respectively. The first driving capacitor comb teeth (2-1-2), the second driving capacitor comb teeth (2-1-3), the third driving capacitor comb teeth (2-1-4) and the fourth driving capacitor comb teeth (2-1-5) are arranged with the driving capacitor comb teeth on both sides of the inner comb tooth support cantilever (2-1-10) to form the first driving comb tooth group. The first detection capacitor comb teeth (2-1-6), the second detection capacitor comb teeth (2-1-7), and the detection capacitor comb teeth arranged on the outside of the outer comb tooth support cantilever (2-1-11) interlock to form the first detection comb tooth group. The fifth driving capacitor comb tooth (2-2-2), the sixth driving capacitor comb tooth (2-2-3), and the driving capacitor comb teeth arranged on the side away from the inner tuning fork resonant beam (2-2-1) on the comb tooth support cantilever (2-2-8) interlock to form the second driving comb tooth group; the third detection capacitor comb tooth (2-2-4), the fourth detection capacitor comb tooth (2-2-5), and the detection capacitor comb teeth arranged on the side near the inner tuning fork resonant beam (2-2-1) on the comb tooth support cantilever (2-2-8) interlock to form the second detection comb tooth group.

5. A coupled stiffness perturbation-type MEMS modal localization accelerometer according to claim 4, characterized in that, The first directional elastic support structure (3-1), the second directional elastic support structure (3-2), the third directional elastic support structure (3-3), and the fourth directional elastic support structure (3-4) have the same structure; The first directional elastic support structure (3-1) consists of a first support anchor point (3-1-1) and a first directional elastic beam (3-1-2), which is used to ensure the good performance and stability of the accelerometer; One end of the first directional elastic beam (3-1-2) is connected to the first support anchor point (3-1-1), and the other end is connected to the sensitive mass block (1).

6. The coupled stiffness perturbation type MEMS modal localization accelerometer according to claim 5, characterized in that, The signal output layer further includes: a first electrode (5-1-1), a second electrode (5-1-2), a third electrode (5-1-3), a fourth electrode (5-1-4), a first drive signal lead-out electrode (5-3-1), a second drive signal lead-out electrode (5-3-2), a third drive signal lead-out electrode (5-3-3), and a fourth drive signal lead-out electrode (5-3-4). The first electrode (5-1-1), the second electrode (5-1-2), the third electrode (5-1-3), and the fourth electrode (5-1-4) are bonded to the first driving capacitor comb teeth (2-1-2), the second driving capacitor comb teeth (2-1-3), the third driving capacitor comb teeth (2-1-4), and the fourth driving capacitor comb teeth (2-1-5), respectively, and are connected to the first driving signal lead-out electrode (5-3-1), the second driving signal lead-out electrode (5-3-2), the third driving signal lead-out electrode (5-3-3), and the fourth driving signal lead-out electrode (5-3-4) respectively, through leads.

7. A coupled stiffness perturbation-type MEMS modal localization accelerometer according to claim 6, characterized in that, The signal output layer further includes: a fifth electrode (5-1-5), a sixth electrode (5-1-6), a first detection signal lead-out electrode (5-3-5), and a second detection signal lead-out electrode (5-3-6); wherein the fifth electrode (5-1-5) and the sixth electrode (5-1-6) are respectively bonded to the first detection capacitor comb tooth (2-1-6) and the second detection capacitor comb tooth (2-1-7), and are respectively connected to the first detection signal lead-out electrode (5-3-5) and the second detection signal lead-out electrode (5-3-6) through leads.

8. The coupled stiffness perturbation type MEMS modal localization accelerometer according to claim 7, characterized in that, The signal output layer further includes: a seventh electrode (5-2-1), an eighth electrode (5-2-2), a fifth driving signal lead-out electrode (5-4-1), and a sixth driving signal lead-out electrode (5-4-2); wherein the seventh electrode (5-2-1) and the eighth electrode (5-2-2) are respectively bonded to the fifth driving capacitor comb teeth (2-2-2) and the sixth driving capacitor comb teeth (2-2-3), and are respectively connected to the fifth driving signal lead-out electrode (5-4-1) and the sixth driving signal lead-out electrode (5-4-2) through leads.

9. A coupled stiffness perturbation type MEMS modal localization accelerometer according to claim 8, characterized in that, The signal output layer further includes: a ninth electrode (5-2-3), a tenth electrode (5-2-4), an eleventh electrode (5-5-1), a twelfth electrode (5-5-2), a thirteenth electrode (5-5-3), a third detection signal lead-out electrode (5-4-3), a fourth detection signal lead-out electrode (5-4-4), a first electrostatic common lead-out electrode (5-6-1), and a common terminal lead-out electrode (5-6-2); wherein the ninth electrode (5-2-3) and the tenth electrode (5-2-4) are bonded to the third detection capacitor comb teeth (2-2-4) and the fourth detection capacitor comb teeth (2-2-5) respectively, and are connected to the third detection signal lead-out electrode (5-4-3) and the fourth detection signal lead-out electrode (5-4-4) through leads; The eleventh electrode (5-5-1) and the twelfth electrode (5-5-2) are bonded to the inner tuning fork resonator beam (2-2-1) and connected to the first electrostatic common lead-out electrode (5-6-1) through leads; The thirteenth electrode (5-5-3) is bonded to the external tuning fork resonator beam (2-1-1) and connected to the common terminal lead-out electrode (5-6-2) via a lead wire.

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