Coupling stiffness disturbance type MEMS modal localization accelerometer

Abstract

The invention provides a coupling stiffness disturbance type MEMS modal localization accelerometer, which is characterized in that a core sensing unit adopts a double-tuning-fork resonator parallel arrangement configuration, and an offset weak coupling resonance system is designed and constructed through the difference of equivalent support stiffness parameters. The outer tuning fork resonator is directly connected with the sensitive mass block, the inner tuning fork resonator realizes full-constraint fixation through a base anchor point, and the outer tuning fork resonator and the inner tuning fork resonator form a double-tuning-fork electrostatic weak coupling resonant structure through an electrostatic coupling parallel plate, so that energy transfer between resonant units is realized. The mechanism of the accelerometer is different from that of a traditional rigidity or quality disturbance mode localization sensor, when the accelerometer is subjected to the action of external acceleration, the inertial micro displacement of the accelerometer is converted into coupling rigidity change of the weak coupling resonance system, the resonance unit amplitude ratio of the weak coupling resonance system is detected through an external circuit, and the detection accuracy is improved. Therefore, the detection of coupling rigidity disturbance is realized, and finally the high-sensitivity detection of the measured acceleration is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of micro-electro-mechanical system and micro-inertial measurement, in particular to a coupling stiffness perturbation type MEMS modal localization accelerometer. BACKGROUND

[0002] With the continuous maturity of micro-electro-mechanical system (MEMS) technology, the modal localization sensor based on weakly coupled resonators has rapidly become a research hotspot in the field of inertial sensing due to its "ultra-high sensitivity" advantage. Unlike traditional resonant accelerometers that rely on frequency shift detection, this type of device senses by monitoring the amplitude ratio change of a weakly coupled resonator system under disturbance, which can theoretically improve the sensitivity by one to three orders of magnitude.

[0003] However, existing modal localization sensors are usually designed based on mass perturbation or stiffness perturbation, which are subject to modal mixing effect and have a theoretical upper limit of mechanical sensitivity that cannot be broken. The mass perturbation type adds a sensitive mass block to one of the coupled resonators to change the effective mass of the resonator by acceleration; the stiffness perturbation type directly changes the stiffness parameter of the resonator by designing an acceleration-sensitive support structure. Although these schemes utilize the modal localization effect, they all face a fundamental theoretical limitation - the modal mixing effect. When the external disturbance (acceleration) increases, the characteristic modes of the weakly coupled system will interact and even exchange, causing the amplitude ratio change rate representing the measured quantity to decrease sharply, saturate, or even reverse. This phenomenon strictly restricts the maximum achievable mechanical sensitivity and linear operating range of the sensor, becoming a theoretical bottleneck that makes it difficult to further improve the performance of existing modal localization sensors. Therefore, a new signal change mode is needed to avoid the modal mixing effect and fully release the ultra-high sensitivity potential of the modal localization principle. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a coupling stiffness perturbation type MEMS modal localization accelerometer to overcome the shortcomings of the prior art. The present application converts the micro-displacement change of the sensitive mass block caused by the external acceleration signal into a coupling stiffness perturbation of the weakly coupled resonator system through the electrostatic negative stiffness effect, thereby constructing an efficient and reliable signal-coupling stiffness conversion topology, and greatly improving the signal conversion efficiency.

[0005] The accelerometer described in the present application adopts a double-layer structure; The double-layer structure includes a signal conversion layer and a signal output layer; The signal conversion layer adopts a silicon micro-mechanical structure; the signal output layer includes a glass insulating layer and a metal signal lead; The silicon micro-mechanical structure is fixed on the upper surface of the glass insulation layer through silicon and glass bonding technology, and the anchor points of the silicon micro-mechanical structure correspond to the positions of the metal signal leads, so as to realize the input and output control of the electrical signal. The silicon micro-mechanical structure comprises a sensitive mass block, a double-tongue resonator and a directional elastic support structure, and the directional elastic support structure comprises 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. The silicon micro-mechanical structure is used for converting the inertial micro-displacement change of the sensitive mass block caused by the external acceleration signal into the change of the electrostatic coupling stiffness of the weakly coupled resonant system, and finally outputting an electrical signal which can be directly measured. The double-tongue resonator is arranged in a parallel arrangement as the core sensitive unit of the accelerometer, and comprises an outer tongue resonator and an inner tongue resonator. The double-tongue resonator is arranged at the center position of the sensitive mass block, and the resonant beams of the outer tongue resonator and the inner tongue resonator are symmetrical about the center of the sensitive mass block, forming a differential structure. The outer tongue resonator is directly connected to the sensitive mass block, the inner tongue resonator is fixed by the base anchor point, and the outer tongue resonator and the inner tongue resonator have different equivalent support stiffness parameters, forming a misaligned weakly coupled resonant system. The outer tongue resonator and the inner tongue resonator are connected by an electrostatic coupling parallel plate to form a double-tongue electrostatic weakly coupled resonant structure, so as to realize energy transmission between the resonant units. When the accelerometer is subjected to external acceleration, the inertial micro-displacement of the sensitive mass block causes the change of the distance between the electrostatic coupling parallel plates, and further causes the change of the coupling stiffness of the weakly coupled resonant system. The accelerometer detects the amplitude ratio of the outer tongue resonator and the inner tongue resonator in the weakly coupled resonant system to detect the coupling stiffness disturbance, and finally realizes high-sensitivity detection of the external acceleration.

[0006] 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 arranged at the right upper, right lower, left lower and left upper positions of the sensitive mass block respectively, and are 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 respectively.

[0007] The double-tongue resonator is used for converting the micro-displacement signal into a capacitance signal which can be measured by a matching circuit. 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. 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. The support stiffness of the inner tuning fork resonator is: The support stiffness of the external tuning fork resonator is , ; 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. 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. 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; 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; 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. .

[0008] The coupling stiffness The relationship between acceleration and acceleration is expressed as follows: , 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.

[0009] 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. The inner comb tooth support cantilever is arranged with driving capacitive combs on both sides; the outer comb tooth support cantilever is arranged with detection capacitive combs on the outer side; The comb tooth support cantilever is arranged with driving capacitive combs and detection capacitive combs on both sides respectively; The first driving capacitive comb, the second driving capacitive comb, the third driving capacitive comb and the fourth driving capacitive comb are staggered and inserted with the driving capacitive combs arranged on both sides of the inner comb tooth support cantilever to form a first driving comb group; The first detection capacitive comb and the second detection capacitive comb are staggered and inserted with the detection capacitive combs arranged on the outer side of the outer comb tooth support cantilever to form a first detection comb group; The fifth driving capacitive comb and the sixth driving capacitive comb are staggered and inserted with the driving capacitive combs arranged on the side of the comb tooth support cantilever far from the inner tuning fork resonant beam to form a second driving comb group; the third detection capacitive comb and the fourth detection capacitive comb are staggered and inserted with the detection capacitive combs arranged on the side of the comb tooth support cantilever close to the inner tuning fork resonant beam to form a second detection comb group.

[0010] The first direction elastic support structure, the second direction elastic support structure, the third direction elastic support structure and the fourth direction elastic support structure have the same structure; The first direction elastic support structure is composed of a first support anchor point and a first direction elastic beam, which is used to ensure good performance and stability of the accelerometer; One end of the first direction elastic beam is connected with the first support anchor point, and the other end is connected with the sensitive mass block.

[0011] The signal output layer further comprises 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; The first electrode, the second electrode, the third electrode and the fourth electrode are respectively bonded with the first driving capacitive comb, the second driving capacitive comb, the third driving capacitive comb and the fourth driving capacitive comb, and are respectively connected with 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 through lead wires.

[0012] The signal output layer further comprises a fifth electrode, a sixth electrode, a first detection signal lead-out electrode and a second detection signal lead-out electrode; the fifth electrode and the sixth electrode are respectively bonded with the first detection capacitive comb and the second detection capacitive comb, and are respectively connected with the first detection signal lead-out electrode and the second detection signal lead-out electrode through lead wires.

[0013] The signal output layer further comprises a seventh electrode, an eighth electrode, a fifth driving signal leading electrode and a sixth driving signal leading electrode; wherein the seventh electrode and the eighth electrode are bonded with the fifth driving capacitor comb tooth and the sixth driving capacitor comb tooth respectively, and are connected with the fifth driving signal leading electrode and the sixth driving signal leading electrode through leading wires respectively.

[0014] The signal output layer further comprises a ninth electrode, a tenth electrode, an eleventh electrode, a twelfth electrode, a thirteenth electrode, a third detection signal leading electrode, a fourth detection signal leading electrode, a first electrostatic common leading electrode and a common terminal leading electrode; wherein the ninth electrode and the tenth electrode are bonded with the third detection capacitor comb tooth and the fourth detection capacitor comb tooth respectively, and are connected with the third detection signal leading electrode and the fourth detection signal leading electrode through leading wires; The eleventh electrode and the twelfth electrode are bonded with the inner tuning fork resonant beam, and are connected with the first electrostatic common leading electrode through leading wires; The thirteenth electrode is bonded with the outer tuning fork resonant beam, and is connected with the common terminal leading electrode through a leading wire.

[0015] The present application has the following beneficial effects relative to the prior art: (1) the present application designs a coupling stiffness disturbance type signal conversion mechanism, and realizes the overall design of the structure based on the conversion mechanism of "external disturbance-micro displacement change-coupling stiffness disturbance", which breaks through the upper limit of the mechanical sensitivity of the traditional modal localized sensor.

[0016] (2) the differential electrostatic coupling parallel plate is used as the core sensitive element, and the efficient conversion of acceleration-coupling stiffness is realized based on the electrostatic negative stiffness principle.

[0017] (3) the double-tuning fork resonator forms a misaligned weak coupling resonant system through the difference design of the equivalent support stiffness parameters, so that the system is locked in the anti-phase working mode, the influence of modal aliasing on the sensitivity is avoided, and the energy dissipation of the resonator is greatly suppressed.

[0018] (4) the double-tuning fork resonant beam integrates the driving / detection comb teeth and the electrostatic coupling plate, realizes the micro displacement-capacitance-stiffness three conversions in the center of the mass block, and constructs an accelerometer with high space utilization and signal conversion efficiency through silicon-glass bonding stacking and vertical signal transmission. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is a schematic diagram of the overall mechanical structure of the present application.

[0020] Figure 2 It is a schematic diagram of the silicon micromechanical structure of the present application.

[0021] Figure 3 It is a schematic diagram of the double-tuning fork resonator structure of the present application.

[0022] Figure 4 Schematic diagram of the directional elastic support structure of the present application.

[0023] Figure 5 Schematic diagram of the glass insulation layer and signal lead-out wire of the present application.

[0024] Figure 6 Acceleration-amplitude ratio response characteristic curve diagram of the present application.

[0025] Legend: 1: sensitive mass; 2: double-tongue resonator; 3: directional elastic support structure; 4: glass insulation layer; 2-1: outer tongue resonator; 2-2: inner tongue resonator; 2-1-1: outer tongue resonator beam; 2-1-2: first drive capacitor comb tooth; 2-1-3: second drive capacitor comb tooth; 2-1-4: third drive capacitor comb tooth; 2-1-5: fourth drive capacitor comb tooth; 2-1-6: first detection capacitor comb tooth; 2-1-7: second detection capacitor comb tooth; 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 support cantilever; 2-1-11: outer comb tooth support cantilever; 2-2-8: comb tooth support cantilever; 2-2-1: inner tongue resonator beam; 2-2-2: fifth drive capacitor comb tooth; 2-2-3: sixth drive capacitor comb tooth; 2-2-4: third detection capacitor comb tooth; 2-2-5: fourth detection capacitor comb tooth; 3-1: first directional elastic support structure; 3-2: second directional elastic support structure; 3-3: third directional elastic support structure; 3-4: fourth directional elastic support structure; 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: first directional elastic beam; 3-2-2: second directional elastic beam; 3-3-2: third directional elastic beam; 3-4-2: fourth directional elastic beam; 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; 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; 5-6-1: First electrostatic common lead-out electrode; 5-6-2: Common terminal lead-out electrode. Detailed Implementation

[0026] 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.

[0027] 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. 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 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. 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. 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. The first direction elastic support structure 3-1, the second direction elastic support structure 3-2, the third direction elastic support structure 3-3 and the fourth direction elastic support structure 3-4 are arranged at the right upper, right lower, left lower and left upper positions of the sensitive mass block 1 respectively, the direction elastic support structure 3 is connected with the sensitive mass block 1 through the first direction elastic beam 3-1-2, the second direction elastic beam 3-2-2, the third direction elastic beam 3-3-2 and the fourth direction elastic beam 3-4-2 at one end, and is fixed on the glass insulation 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 at the other end, so that the sensitive mass block 1 is uniformly supported to form a suspended mass system for sensing the horizontal plane acceleration.

[0028] As shown in Figure 3 The double-tuning fork resonator 2 includes an outer tuning fork resonator 2-1 and an inner tuning fork resonator 2-2 for converting a micro-displacement signal into a capacitance signal that can be measured by a matching circuit; The outer tuning fork resonator 2-1 includes an outer 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 drive capacitance comb tooth 2-1-2, a second drive capacitance comb tooth 2-1-3, a third drive capacitance comb tooth 2-1-4, a fourth drive capacitance comb tooth 2-1-5, a first detection capacitance comb tooth 2-1-6 and a second detection capacitance 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 drive capacitance comb tooth 2-2-2, a sixth drive capacitance comb tooth 2-2-3, a third detection capacitance comb tooth 2-2-4 and a fourth detection capacitance comb tooth 2-2-5; The inner tuning fork resonator 2-2 is fixed by full constraint through a substrate anchor point, and the support stiffness is higher; the outer tuning fork resonator 2-1 is connected with the sensitive mass block 1, and the support stiffness is lower ); the difference in support stiffness of the two forms a detuned weakly coupled resonant system, locks the anti-phase working mode and can effectively suppress energy dissipation to improve the system quality factor; wherein the stiffness difference of the two is represented by mechanical stiffness disturbance . (1), The outer tuning fork resonator beam 2-1-1 of the double tuning fork resonator 2 is connected with a first electrostatic coupling parallel plate 2-1-8 and a second electrostatic coupling parallel plate 2-1-9 on the inner side; the outer side of the inner tuning fork resonator beam 2-2-1 is connected with 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 arranged at an initial interval d The second electrostatic coupling parallel plate 2-1-9 and the fourth electrostatic coupling parallel plate 2-2-6 are arranged at an initial interval d The second electrostatic coupling parallel plate group is arranged oppositely, and the arrangement direction of the electrostatic coupling parallel plate group is a horizontal direction; wherein 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 outer tuning fork resonator 2-1 to move, the interval d between the two groups of parallel plates is differentially changed, the common mode error is suppressed, and the coupling stiffness is changed through the electrostatic negative stiffness effect ; The coupling stiffness The relationship between the acceleration and the coupling stiffness is expressed as: (2), Wherein, 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 the acceleration; A is the overlapping area of the first electrostatic coupling parallel plate, the third electrostatic coupling parallel plate and the second electrostatic coupling parallel plate, and the fourth electrostatic coupling parallel plate, is the difference between the bias voltage applied between the first electrostatic coupling parallel plate, the third electrostatic coupling parallel plate and the second electrostatic coupling parallel plate, and the fourth electrostatic coupling parallel plate; is the dielectric constant.

[0029] The micro displacement of the electrostatic coupling parallel plate caused by the acceleration The expression is: (3), Wherein, represents the micro displacement and the acceleration conversion gain, which is negatively related to the elastic beam stiffness in the elastic support structure and positively related to the equivalent stiffness of the mass block, is the input acceleration.

[0030] The outer tuning fork resonator beam 2-1-1 of the double tuning fork resonator 2 is connected with an inner comb tooth support cantilever 2-1-10 and an outer comb tooth support cantilever 2-1-11 on the outer side; the inner tuning fork resonator beam 2-2-1 is connected with a comb tooth support cantilever 2-2-8 on the inner side; The drive capacitive comb teeth are arranged on both sides of the inner comb tooth support cantilever 2-1-10 outside the outer sound fork resonant beam 2-1-1; the detection capacitive comb teeth are arranged on the outside of the outer comb tooth support cantilever 2-1-11; the drive capacitive comb teeth and the detection capacitive comb teeth are respectively arranged on both sides of the comb tooth support cantilever 2-2-8 inside the inner sound fork resonator 2-2-1; The first drive capacitive comb teeth 2-1-2, the second drive capacitive comb teeth 2-1-3, the third drive capacitive comb teeth 2-1-4 and the fourth drive capacitive comb teeth 2-1-5 are staggered and inserted into the drive capacitive comb teeth arranged on both sides of the inner comb tooth support cantilever 2-1-10 to form a first drive comb tooth group; the fifth drive capacitive comb teeth 2-2-2 and the sixth drive capacitive comb teeth 2-2-3 are staggered and inserted into the drive capacitive comb teeth arranged on the side of the comb tooth support cantilever 2-2-8 away from the inner sound fork resonator 2-2-1 to form a second drive comb tooth group; The first detection capacitive comb teeth 2-1-6 and the second detection capacitive comb teeth 2-1-7 are staggered and inserted into the detection capacitive comb teeth arranged on the outside of the outer comb tooth support cantilever 2-1-11 to form a first detection comb tooth group; the third detection capacitive comb teeth 2-2-4 and the fourth detection capacitive comb teeth 2-2-5 are staggered and inserted into the detection capacitive comb teeth arranged on the side of the comb tooth support cantilever 2-2-8 close to the inner sound fork resonator 2-2-1 to form a second detection comb tooth group. Wherein, the first drive capacitive comb teeth 2-1-2 and the third drive capacitive comb teeth 2-1-4 are applied with positive phase drive signals, and the second drive capacitive comb teeth 2-1-3 and the fourth drive capacitive comb teeth 2-1-5 are applied with inverse phase drive signals; for keeping vibrating at its natural frequency when the sensitive mass 1 drives the outer sound fork resonator 2-1 to micro-displace.

[0031] As shown in Figure 4 The first direction elastic support structure 3-1, the second direction elastic support structure 3-2, the third direction elastic support structure 3-3 and the fourth direction elastic support structure 3-4 are completely same in structure; wherein the first direction elastic support structure 3-1 is composed of a first support anchor point 3-1-1 and a first direction elastic beam 3-1-2; the second direction elastic support structure 3-2 is composed of a second support anchor point 3-2-1 and a second direction elastic beam 3-2-2; the third direction elastic support structure 3-3 is composed of a third support anchor point 3-3-1 and a third direction elastic beam 3-3-2; the fourth direction elastic support structure 3-4 is composed of a fourth support anchor point 3-4-1 and a fourth direction elastic beam 3-4-2; taking the first direction elastic support structure 3-1 as an example, one end of the first direction elastic beam 3-1-2 is connected with the first support anchor point 3-1-1, and the other end is connected with the sensitive mass 1, for ensuring good performance and stability of the accelerometer.

[0032] The electrode and the lead wire distribution on the surface of the glass insulation layer 4 in the application are as shown in Figure 5The signal output layer further comprises: 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 driving signal lead-out electrode 5-3-1, a second driving signal lead-out electrode 5-3-2, a third driving signal lead-out electrode 5-3-3, and a fourth driving 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 respectively bonded with 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 with 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 through lead wires.

[0033] The signal output layer further comprises: 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 with the first detection capacitor comb tooth 2-1-6 and the second detection capacitor comb tooth 2-1-7, and are respectively connected with the first detection signal lead-out electrode 5-3-5 and the second detection signal lead-out electrode 5-3-6 through lead wires.

[0034] The signal output layer further comprises: 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 with the fifth driving capacitor comb tooth 2-2-2 and the sixth driving capacitor comb tooth 2-2-3, and are respectively connected with the fifth driving signal lead-out electrode 5-4-1 and the sixth driving signal lead-out electrode 5-4-2 through lead wires.

[0035] The signal output layer further comprises: 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 with the third detection capacitor comb tooth 2-2-4 and the fourth detection capacitor comb tooth 2-2-5, and are connected with the third detection signal lead-out electrode 5-4-3 and the fourth detection signal lead-out electrode 5-4-4 through lead wires; The eleventh electrode 5-5-1 and the twelfth electrode 5-5-2 are bonded with the inner sound fork resonant beam 2-2-1, and are connected with the first electrostatic common lead-out electrode 5-6-1 through lead wires; The thirteenth electrode 5-5-3 is bonded with the outer tuning fork resonator beam 2-1-1, and is connected with the common terminal lead-out electrode 5-6-2 through a lead wire.

[0036] The application adopts a parallel arrangement configuration of double tuning fork resonators, in which the outer tuning fork resonator is directly connected with the sensitive mass block, the inner tuning fork resonator is fixed by full constraint through the base anchor point, and the two are coupled in stiffness through the electrostatic coupling parallel plate. When the accelerometer is subjected to external acceleration, the sensitive mass block micro-displacement drives the outer tuning fork resonator to move, changes the distance d between the electrostatic coupling parallel plates, and based on the electrostatic negative stiffness effect, the micro-displacement change is directly converted into the coupling stiffness disturbance of the weakly coupled resonant system, and finally reacts as the difference in the vibration amplitude of the double tuning fork resonator. By measuring the ratio change of the vibration amplitude of the double tuning fork resonator, the size of the measured acceleration value can be inversely deduced. The ratio expression of the vibration amplitude of the double tuning fork resonator is: (4), Wherein, is the mechanical stiffness disturbance of the inner and outer tuning fork resonator beams, is the coupling stiffness.

[0037] When an alternating driving voltage is applied to the driving capacitance comb teeth of the double tuning fork resonator, the inner and outer tuning fork resonator beams will produce forced vibration. By utilizing the significant stiffness difference between the inner tuning fork resonator and the outer tuning fork resonator connected with the mass block, the weakly coupled resonant system is stably operated in a low-dissipation anti-phase vibration mode, effectively suppressing energy dissipation to improve the system quality factor. Subsequently, the comb teeth group captures the output signal, which is converted by capacitance-voltage and accurately locked and tracked to the resonant frequency of the anti-phase mode by a closed-loop phase-locked circuit.

[0038] In the embodiment, the key structural parameters of the core sensitive unit double tuning fork resonator are set as: 1. The inner tuning fork resonator beam has a length of 1712 μm, a width of 10 μm, and an equivalent support stiffness of ; 2. The outer tuning fork resonator beam has a length of 1722 μm, a width of 10 μm, and an equivalent support stiffness of ; 3. The first, second, third, and fourth electrostatic coupling parallel plates have a length of 1712 μm, a height of 80 μm, and an overlapping area A = 136,960 μm²; 4. The difference between the bias voltages applied between the electrostatic coupling parallel plates = 60 V; 5. The micro-displacement-acceleration conversion gain = 0.33 g / μm; 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: = (5), 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.

[0039] Meanwhile, the structural parameters of this embodiment satisfy the minimum coupling stiffness condition for avoiding modal aliasing effects: , Where k is the equivalent stiffness of the resonator (which can be taken as...). and (average) This is the system quality factor.

[0040] 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-perturbed MEMS modal-localized accelerometer, comprising: The accelerometer adopts a double-layer structure; The double-layer structure comprises a signal conversion layer and a signal output layer; The signal conversion layer adopts a silicon micromechanical structure; the signal output layer comprises a glass insulation layer (4) and a metal signal lead; The silicon micromechanical structure is fixed on the upper surface of the glass insulation layer (4) through a silicon-glass bonding technology, and the anchor points of the silicon micromechanical structure correspond to the positions of the metal signal lead, so as to realize the input and output control of electrical signals; The silicon micromechanical structure comprises a sensitive mass block (1), a double-tuning fork resonator (2) and a directional elastic support structure (3), and the directional elastic support structure (3) comprises 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 inertial micro-displacement change of the external acceleration signal through the sensitive mass block (1) into the change of the electrostatic coupling stiffness of the weakly coupled resonant system, and finally output an electrical signal which can be directly measured. The double-tuning fork resonator (2) is arranged in a parallel arrangement manner and is used as the core sensitive unit of the accelerometer, and comprises 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 position of the sensitive mass block (1), and the resonant beams of the outer tuning fork resonator (2-1) and the inner tuning fork resonator (2-2) are symmetric 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 fixed by full-constraint anchors, and the outer tuning fork resonator (2-1) and the inner tuning fork resonator (2-2) have equivalent support stiffness parameter differences, forming a misaligned 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, forming a double-tuning fork electrostatic weakly coupled resonant structure, so as to realize the energy transmission between the resonant units. When the accelerometer is subjected to external acceleration, the inertial micro-displacement of the sensitive mass block (1) causes the spacing change of the electrostatic coupling parallel plate, and further causes the coupling stiffness change of the weakly coupled resonant system. The accelerometer detects 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, realizes the detection of the coupling stiffness disturbance, and finally realizes the high-sensitivity detection of the external acceleration.

2. A stiffness-perturbed MEMS modal-localization accelerometer according to claim 1, wherein, 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 arranged at the right upper, right lower, left lower and left upper positions of the sensitive mass block (1) respectively, and are 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) respectively.

3. A stiffness-perturbed MEMS modal-localization accelerometer according to claim 2, wherein, 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 support stiffness of the inner tuning fork resonator (2-2) is , and the support stiffness of the outer tuning fork resonator (2-1) is , ; 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 arranged in an initial interval The first electrostatic coupling parallel plate group is formed by the oppositely arranged first electrostatic coupling parallel plates. The second electrostatic coupling parallel plate (2-1-9) and the fourth electrostatic coupling parallel plate (2-2-6) are arranged in an initial interval The second electrostatic coupling parallel plate group is formed by the oppositely arranged The first electrostatic coupling parallel plate group and the second electrostatic coupling parallel plate group are both arranged in a horizontal direction. The first and second electrostatic coupling parallel plate sets are symmetrically distributed, the sensitive mass (1) moves the micro-displacement driven outer sound fork resonator (2-1), the differential changes the distance d, the common mode error suppression is realized, and the coupling stiffness is changed through the electrostatic negative stiffness effect .

4. A stiffness-perturbed MEMS modal-localization accelerometer according to claim 3, wherein, The coupling stiffness The relationship between the acceleration and the force is expressed as: ， wherein, represents the micro displacement of the first and second electrostatic coupling parallel plates (2-1-8, 2-1-9) caused by acceleration; A is the overlapping area of the first and third electrostatic coupling parallel plates and the second and fourth electrostatic coupling parallel plates, is the difference between the bias voltages applied between the first and third electrostatic coupling parallel plates and the second and fourth electrostatic coupling parallel plates; is the dielectric constant.

5. A stiffness-perturbed MEMS modal-localization accelerometer according to claim 4, wherein, 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 teeth (2-2-2), the sixth driving capacitor comb teeth (2-2-3) and the driving capacitor comb teeth arranged on the side of the comb tooth support cantilever (2-2-8) far away from the inner tuning fork resonant beam (2-2-1) form a second driving comb teeth group by staggered insertion; 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 side of the comb tooth support cantilever (2-2-8) close to the inner tuning fork resonant beam (2-2-1) form a second detection comb teeth group by staggered insertion.

6. A stiffness-perturbed MEMS modal-localization accelerometer according to claim 5, wherein, The first direction elastic support structure (3-1), the second direction elastic support structure (3-2), the third direction elastic support structure (3-3) and the fourth direction elastic support structure (3-4) have the same structure; The first direction elastic support structure (3-1) is composed of a first support anchor point (3-1-1) and a first direction elastic beam (3-1-2), and is used for ensuring good performance and stability of the accelerometer; One end of the first direction elastic beam (3-1-2) is connected with the first support anchor point (3-1-1), and the other end is connected with the sensitive mass block (1).

7. A stiffness-perturbed MEMS modal-localization accelerometer according to claim 6, wherein, The signal output layer further comprises: 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 driving signal output electrode (5-3-1), a second driving signal output electrode (5-3-2), a third driving signal output electrode (5-3-3) and a fourth driving signal output 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 respectively bonded with 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), and are respectively connected with 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 lead wires.

8. The coupled-stiffness perturbed MEMS modal localized accelerometer of claim 7, wherein, The signal output layer further comprises: a fifth electrode (5-1-5), a sixth electrode (5-1-6), a first detection signal output electrode (5-3-5) and a second detection signal output electrode (5-3-6); the fifth electrode (5-1-5) and the sixth electrode (5-1-6) are respectively bonded with the first detection capacitor comb teeth (2-1-6) and the second detection capacitor comb teeth (2-1-7), and are respectively connected with the first detection signal output electrode (5-3-5) and the second detection signal output electrode (5-3-6) through lead wires.

9. A stiffness-perturbed MEMS modal-localization accelerometer according to claim 8, wherein, The signal output layer further comprises a seventh electrode (5-2-1), an eighth electrode (5-2-2), a fifth driving signal leading electrode (5-4-1) and a sixth driving signal leading electrode (5-4-2); wherein the seventh electrode (5-2-1) and the eighth electrode (5-2-2) are bonded with the fifth driving capacitor comb tooth (2-2-2) and the sixth driving capacitor comb tooth (2-2-3) respectively, and are connected with the fifth driving signal leading electrode (5-4-1) and the sixth driving signal leading electrode (5-4-2) through leading wires respectively.

10. The coupled-stiffness perturbed MEMS modal localized accelerometer of claim 9, wherein, The signal output layer further comprises 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 leading electrode (5-4-3), a fourth detection signal leading electrode (5-4-4), a first electrostatic common leading electrode (5-6-1) and a common terminal leading electrode (5-6-2); wherein the ninth electrode (5-2-3) and the tenth electrode (5-2-4) are bonded with the third detection capacitor comb tooth (2-2-4) and the fourth detection capacitor comb tooth (2-2-5) respectively, and are connected with the third detection signal leading electrode (5-4-3) and the fourth detection signal leading electrode (5-4-4) through leading wires; The eleventh electrode (5-5-1) and the twelfth electrode (5-5-2) are bonded with the inner sound fork resonant beam (2-2-1), and are connected with the first electrostatic common leading electrode (5-6-1) through leading wires; The thirteenth electrode (5-5-3) is bonded with the outer sound fork resonant beam (2-1-1), and is connected with the common terminal leading electrode (5-6-2) through a leading wire.

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