阅读说明：本技术 一种面向谐振式mems传感器的拱形谐振器及mems加速度计 (Arched resonator and MEMS accelerometer for resonant MEMS sensor ) 是由 李城鑫 赵纯 于 2020-07-20 设计创作，主要内容包括：本发明公开了一种面向谐振式MEMS传感器的拱形谐振器及MEMS加速度计,拱形谐振器包括：锚定系统,以及与锚定系统连接的拱形谐振梁；通过锚定系统给拱形谐振梁施加用于调节拱形高度的热电流,在热电流作用下,通过拱形谐振梁产生的热应变来调控所述拱形谐振梁的刚度,使得拱形谐振梁的刚度在同相模态频率和反向模态频率之间实现交叉,进而调节模态耦合或工作区间。本发明改变了谐振器的拱形梁高度,而拱形高度的变化增大了模态之间的频率差,进而提高了灵敏度；同时,本发明通过热电流对拱形结构产生了模态耦合,拱形高度变化使得谐振器的拱形梁的模态中一个模态对应力应变敏感,另一个模态不敏感的特点,可实现差分检测。(The invention discloses an arched resonator and an MEMS accelerometer facing a resonant MEMS sensor, wherein the arched resonator comprises: the device comprises an anchoring system and an arched resonant beam connected with the anchoring system; the method comprises the steps that thermoelectric current for adjusting the height of an arch is applied to an arch resonant beam through an anchoring system, and the rigidity of the arch resonant beam is adjusted and controlled through thermal strain generated by the arch resonant beam under the action of the thermoelectric current, so that the rigidity of the arch resonant beam is crossed between in-phase modal frequency and reverse modal frequency, and further modal coupling or a working interval is adjusted. The invention changes the height of the arched beam of the resonator, and the change of the arched height increases the frequency difference between the modes, thereby improving the sensitivity; meanwhile, modal coupling is generated on the arched structure through the thermoelectric current, and the change of the arched height enables one mode of the modes of the arched beam of the resonator to be sensitive to stress and strain and the other mode of the modes to be insensitive, so that differential detection can be realized.)

1. An arcuate resonator for a resonant MEMS sensor, comprising: the device comprises an anchoring system and an arched resonant beam connected with the anchoring system;

and applying thermal current for adjusting the height of the arch to the arch resonance beam through the anchoring system, and regulating and controlling the rigidity of the arch resonance beam through thermal strain generated by the arch resonance beam under the action of the thermal current so that the rigidity or the structure of the arch resonance beam is crossed between in-phase modal frequency and reverse modal frequency, thereby adjusting modal coupling or a working interval.

2. The arcuate resonator of claim 1, wherein said anchoring system comprises: anchor point (1) and anchor point tie-beam (2), anchor point (1) pass through anchor point tie-beam (2) with the arch resonant beam is connected, anchor point (1) is as the tie point of applying the thermal current.

3. The arcuate resonator of claim 1 or 2, wherein the arcuate resonator beam comprises: a first resonant beam (3), a second resonant beam (4) and a coupling beam (5);

the first resonance beam (3) and the second resonance beam (4) are arranged in axial symmetry, two ends of the first resonance beam (3) and the second resonance beam (4) are coincided with two ends of a coupling beam (5) along the tangential direction of the arched bend, and the first resonance beam (3) is connected with the second resonance beam (4) through two aligned ends of the coupling beam (5).

4. The arcuate resonator of any of claims 1-3, wherein, in operation, when the arcuate resonator beam is subjected to an axial stress, the height of the arcuate structure is laterally altered, which in turn alters the strain-frequency sensitivity of the structure's detection.

5. A MEMS accelerometer based on the dome resonator of any one of claims 1-4, comprising: the device comprises a first resonator, a second resonator, a spring mass system and two lever systems;

the spring mass system is directly connected with the left lever system and the right lever system along the axial center line of the spring mass system, the two lever systems are in mirror symmetry with respect to the vertical center line, the first resonator and the second resonator are respectively directly connected with the left lever system and the right lever system along the axial center line of the spring mass system, and the first resonator and the second resonator are in mirror symmetry with respect to the vertical center line.

6. The MEMS accelerometer of claim 5, wherein the first resonator and the second resonator act as an axial strain sensing element of the MEMS accelerometer, and the first resonator and the second resonator are structurally identical, each comprising: the device comprises an anchor point (1), an anchor point connecting beam (2), a first resonant beam (3), a second resonant beam (4) and a coupling beam (5);

the anchor point (1) is connected with the arched resonant beam through the anchor point connecting beam (2);

the two ends of the first resonant beam (3) and the second resonant beam (4) are superposed with the two ends of the coupling beam (5) along the tangent direction of the arch bending, and the first resonant beam (3) is connected with the second resonant beam (4) through the two aligned ends of the coupling beam (5).

7. The MEMS accelerometer according to claim 5 or 6, wherein the lever system comprises: the device comprises an input beam (8), a force arm (9), a fulcrum beam (10) and an output beam (11);

the input beam (8) and the output beam (11) are distributed on two sides of the fulcrum beam (10) along the axial direction of the first resonator, and the input beam (8) and the output beam (11) are distributed on two sides of the force arm (9) along the direction perpendicular to the axial direction of the first resonator;

the ratio of the distance between the output beam (11) and the fulcrum beam (10) to the distance between the fulcrum beam (10) and the input beam (8) constitutes a lever system amplification ratio.

8. The MEMS accelerometer of any of claims 5-7, wherein the spring-mass system is configured to convert sensitive acceleration into a change in displacement and transfer the change to the lever system, the spring-mass system comprising: a cantilever beam (6) and a mass block (7); the cantilever beams (6) are distributed in a central symmetry mode relative to the mass block (7).

Technical Field

The invention belongs to the technical field of resonators, and particularly relates to an arched resonator and an MEMS accelerometer facing a resonant MEMS sensor.

Background

The resonant beam structure is the most common mechanical structure form in systems such as a resonant acceleration sensor, a resonant pressure sensor, a resonant magnetic sensor and the like. Taking a resonant acceleration sensor as an example, the prior art adopts axial stress change caused by inertia force (Zhao C, Pandit M, et al. Journal of microelectromechanical Systems,2019:1-3.), and similar work also includes (Pandit M, Zhao C, et al. Journal of microelectromechanical Systems,2019, PP (99):1-8, etc.), or the change of mass displacement further causes the change of electrostatic rigidity (CN110040680A, CN110078014A), so that the frequency of the resonant beam changes. The detection method based on the axial stress change is generally good in stability, but low in sensitivity; the detection method based on the electrostatic rigidity change is high in sensitivity, but poor in stability, and unstable phenomena such as electrostatic adsorption are easy to occur, so that a device is damaged.

In recent years, arched beam structures have been widely used in thermoelectric actuators, modal localization, etc. due to their outstanding dynamic behavior. The university of aca king science first utilizes the abundant linear mechanical effect of the arched beam structure to study the aspects of modal coupling effect and the like, and extends the research into the field of nonlinear dynamics. The West's university of traffic utilizes the arched beam to make the negative stiffness roof beam of thermoelectric drive, and uses it in MEMS accelerometer to realize the high resolution detection of acceleration. Similar works also include (Hajjaj A Z., International Journal of Non Linear Mechanics,2018,107(DEC.):64-72.), etc. The existing research relates to that the structure is presented in a single arched beam structure form, the single arched beam with a fixed single end has poor transverse and axial strain linearity, and the effective working area of the sensor is greatly reduced.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide an arched resonator for a resonant MEMS sensor, and aims to solve the problems of poor transverse and axial strain linearity and low sensitivity caused by the adoption of a single-end fixed single arched beam structure in the prior art.

The invention provides an arched resonator facing a resonant MEMS sensor, which comprises: the device comprises an anchoring system and an arched resonant beam connected with the anchoring system; the method comprises the steps that a thermoelectric current for adjusting the height of an arch is applied to the arch resonance beam through an anchoring system, and the rigidity of the arch resonance beam is adjusted and controlled through the thermal strain generated by the arch resonance beam under the action of the thermoelectric current, so that the rigidity or the structure of the arch resonance beam is crossed between in-phase modal frequency and reverse modal frequency, and further modal coupling or a working interval is adjusted.

Still further, the anchoring system comprises: the anchor point is connected with the arched resonant beam through the anchor point connecting beam and serves as a connecting point for applying thermal current.

Further, the arched resonance beam includes: the first resonant beam, the second resonant beam and the coupling beam; the first resonance beam and the second resonance beam are symmetrically arranged around the axial direction, two ends of the first resonance beam and two ends of the second resonance beam are superposed with two ends of the coupling beam along the tangential direction of the arched bend, and the first resonance beam and the second resonance beam are connected through two aligned ends of the coupling beam.

When the device works, after the arched resonant beam is subjected to axial stress, the height of the arched structure is changed along the transverse direction, and then the strain-frequency sensitivity of the self-structure detection is changed.

The invention also provides a MEMS accelerometer based on the arch resonator, which comprises: the device comprises a first resonator, a second resonator, a spring mass system and two lever systems; the spring mass system is directly connected with the left lever system and the right lever system along the axial center line of the spring mass system, the two lever systems are in mirror symmetry with respect to the vertical center line, the first resonator and the second resonator are respectively directly connected with the left lever system and the right lever system along the axial center line of the spring mass system, and the first resonator and the second resonator are in mirror symmetry with respect to the vertical center line.

Furthermore, the first resonator and the second resonator are used as an axial strain sensing unit of the MEMS accelerometer, and the first resonator and the second resonator have the same structure and both include: the device comprises an anchor point, an anchor point connecting beam, a first resonant beam, a second resonant beam and a coupling beam; the anchor point is connected with the arched resonant beam through the anchor point connecting beam; the two ends of the first resonant beam and the second resonant beam are superposed with the two ends of the coupling beam along the tangent direction of the arch bending, and the first resonant beam and the second resonant beam are connected through the two aligned ends of the coupling beam.

Still further, the lever system comprises: the input beam, the force arm, the fulcrum beam and the output beam; the input beam and the output beam are distributed on two sides of the fulcrum beam along the axial direction of the first resonator, and the input beam and the output beam are distributed on two sides of the force arm along the direction perpendicular to the axial direction of the first resonator; the ratio of the distance between the output beam and the fulcrum beam to the distance between the fulcrum beam and the input beam constitutes the amplification ratio of the lever system.

Furthermore, the spring mass system is used as an accelerometer sensing unit, sensitive acceleration is converted into displacement change and transmitted to the lever system, and the strain displacement is amplified by the lever system and then converted into arch height change of the first resonator and the second resonator. The spring mass system comprises: a cantilever beam and a mass block; the cantilever beams are distributed symmetrically about the center of the mass block.

Compared with the prior resonant sensor technology, the invention has the following advantages:

(1) the invention adopts a detection mode of changing the height of the arched beam of the resonator by the measurement (such as temperature, acceleration and the like), increases the frequency difference between the modes through the change of the arched height, and further improves the sensitivity.

(2) The invention generates modal coupling to the arched structure by the thermoelectric current, and the change of the arched height ensures that one mode in the modes of the arched beam of the resonator is sensitive to stress and strain and the other mode is insensitive, thereby realizing differential detection.

(3) Compared with the conventional anchor point, the semi-circular anchor point has smaller axial stress, so that the resonant beam has smaller anchor point energy loss at the anchor point, and the structure has higher quality factor.

Drawings

FIG. 1 is a schematic structural diagram of a MEMS resonant arched beam according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a MEMS accelerometer structure with respect to a dome resonator according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of the operation of a MEMS dome resonator provided by an embodiment of the present invention;

FIG. 4 is a graph of the modal frequency of a MEMS dome resonator provided by an embodiment of the present invention (no or low damping case);

FIG. 5 is a graph of the multi-order mode strain-frequency relationship of the MEMS dome resonator provided by the embodiment of the present invention (no damping or low damping condition);

fig. 6 is a sensitivity plot (no damping or low damping case) of a MEMS dome resonator provided by an embodiment of the present invention.

The reference numerals have the following meanings: the device comprises an anchor point 1, an anchor point connecting beam 2, a first resonance beam 3, a second resonance beam 4, a coupling beam 5, an accelerometer cantilever beam 6, a mass block 7, an input beam 8, a force arm 9, a support beam 10, an output beam 11 and a connecting beam 12, wherein the input beam 8, the force arm, the support beam 10, the output beam and the connecting beam are respectively arranged on the two sides of the force amplifying lever.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The present invention provides a resonator structure that can be used to improve strain-frequency sensitivity. The structure is formed by connecting two pairs of arc-shaped bending beams and the semicircular rings in parallel, and the structure utilizes a semicircular annular anchor point connection mode, so that the loss of the structural anchor point is effectively reduced under the condition of not changing the coupling strength of a beam body, and the quality factor is improved.

When the resonator of the arched beam structure is subjected to axial stress, the height of the arched structure is changed along the transverse direction, and then the strain-frequency sensitivity detected by the self structure is changed, the sensitivity of a first-order mode of the resonator to the strain-frequency is greatly improved through the design of the arched beam, the second-order mode of the resonator is insensitive to the axial strain, and the strain-frequency sensitivity of the resonator can be effectively improved through frequency difference.

In the invention, under the action of thermal current, the thermal strain generated by the beam structure of the resonator can regulate and control the rigidity of the beam structure in the arched resonator, so that the rigidity of two resonant beams in the structure or the same-phase and reverse mode frequencies of the structure can be crossed. In the embodiment, the monocrystalline silicon with the thickness of 25 μm is selected, the structure is prepared by a deep silicon penetration etching process, and the thermal deformation quantity of the arched resonant beam structure caused by the thermal current is large, so that the range of modal frequency difference is large, and the bandwidth to be measured is effectively improved.

Fig. 1 is a schematic diagram illustrating an arch-shaped resonant arch-shaped weak coupling structure facing a resonant MEMS sensor according to an embodiment of the present invention; the structure consists of an anchoring system and an arched resonant beam connected with the anchoring system; the method comprises the steps that a thermoelectric current for adjusting the height of an arch is applied to an arch resonant beam through an anchoring system, and the rigidity of the arch resonant beam is adjusted and controlled through thermal strain generated by the arch resonant beam under the action of the thermoelectric current, so that the rigidity or the structure of the arch resonant beam is crossed between in-phase modal frequency and reverse modal frequency, and further modal coupling or a working interval is adjusted.

Wherein, the anchoring system includes: anchor point 1 and anchor point tie-beam 2, anchor point 1 passes through anchor point tie-beam 2 and is connected with the resonant beam of arch, and the anchor point is as the tie point of applying the thermal current.

The arched resonance beam includes: a first resonant beam 3, a second resonant beam 4 and a coupling beam 5; the first resonant beam 3 and the second resonant beam 4 are arranged symmetrically about the axial direction, two ends of the first resonant beam 3 and the second resonant beam 4 are superposed with two ends of the coupling beam 5 along the tangent direction of the arch bending, and the first resonant beam 3 and the second resonant beam 4 are connected through two aligned ends of the coupling beam 5.

The anchor point 1 may be configured to apply a thermal current to the arched resonator system, and the thermal current may be configured to adjust the arched heights of the first resonant beam 3 and the second resonant beam 4, thereby adjusting the modal coupling or the working range. When the device works, after the arched resonant beam is subjected to axial stress, the height of the arched structure is changed along the transverse direction, and then the strain-frequency sensitivity of the self-structure detection is changed.

Fig. 2 is a schematic structural diagram of a MEMS accelerometer based on the dome resonator according to an embodiment of the present invention; the structure includes: the device comprises a first resonator, a second resonator, a spring mass system and two lever systems; the spring mass system is directly connected with the left lever system and the right lever system along the axial center line of the spring mass system, the two lever systems are in mirror symmetry with respect to the vertical center line, the first resonator and the second resonator are respectively directly connected with the left lever system and the right lever system along the axial center line of the spring mass system, and the first resonator and the second resonator are in mirror symmetry with respect to the vertical center line.

The first resonator and the second resonator are used as an axial strain sensing unit of the MEMS accelerometer, the structures of the first resonator and the second resonator are the same, and the first resonator and the second resonator both comprise: the device comprises an anchor point 1, an anchor point connecting beam 2, a first resonant beam 3, a second resonant beam 4 and a coupling beam 5; the anchor point 1 is connected with the arched resonant beam through an anchor point connecting beam 2; the two ends of the first resonant beam 3 and the second resonant beam 4 are overlapped with the two ends of the coupling beam 5 along the tangent direction of the arch bending, and the first resonant beam 3 and the second resonant beam 4 are connected through the two aligned ends of the coupling beam 5.

The lever system includes: an input beam 8, a force arm 9, a fulcrum beam 10 and an output beam 11; the input beam 8 and the output beam 11 are distributed on two sides of the fulcrum beam 10 along the axial direction of the first resonator, and the input beam 8 and the output beam 11 are distributed on two sides of the force arm 9 along the direction perpendicular to the axial direction of the first resonator; the ratio of the distance between the output beam 11 and the fulcrum beam 10 to the distance between the fulcrum beam 10 and the input beam 8 constitutes the lever system amplification ratio.

The spring-mass system is used for converting sensitive acceleration into displacement change and transmitting the displacement change to the lever system, and comprises: a cantilever beam 6 and a mass block 7; the cantilever beams 6 are distributed centrosymmetrically with respect to the mass 7. The spring mass system is converted into the axial force of the resonator through the lever system in the acceleration environment, and the axial force enables the arch heights of the first resonant beam 3 and the second resonant beam 4 to change, so that the modal frequency of the structure is influenced.

Fig. 3 is a schematic diagram of the operation of a MEMS dome resonator. Under the action of the lateral acceleration, the resonant beam structure is subjected to the action of the moment of couple to generate the lateral displacement, and taking the axial acceleration of the arched resonator as an example, the lateral displacement is increased by the prestress design of the arched resonator structure.

S_freq-g＝S_freq-b0*S_b0-g……(1)

In the formula, S_freq-b0For frequency-arch high gradient, S, in the modal coupling diagram of the arch resonator_b0-gFor the acceleration-camber slope, S in the diagram of the effect of axial acceleration on camber of the resonator_freq-gAcceleration sensitivity is detected for the resonator.

FIG. 4 is a graph of the modal frequency of a MEMS dome resonator with no or low damping. Under the action of the thermal current, the working ranges of the first-order in-phase mode and the second-order in-phase mode of the arched resonator structure are adjusted to be in the black frame line area marked in the figure 3. In the embodiment, the width of an anchor point connecting beam of the structure of the arch resonator is designed to be 10um, and the length and width values of the first resonant beam 3 and the second resonant beam 4 are respectively designed to be 800um and 6 um; the minimum radius design value of the connecting beam is 6 mu m.

FIG. 5 is a graph of strain-frequency dependence of multiple order modes of a MEMS dome resonator without damping or with low damping. When the resonator of the arched beam structure is subjected to axial stress, the height of the arched structure is changed along the transverse direction, the sensitivity of the first-order mode of the resonator to strain-frequency is greatly improved by the design of the arched beam, and the second-order mode of the resonator is insensitive to axial strain.

Fig. 6 is a sensitivity diagram of the MEMS arched resonator without damping or low damping, the design of the arched beam greatly improves the frequency difference between the first-order in-phase mode and the second-order in-phase mode of the resonator, and the strain-frequency sensitivity is improved by deduction of the frequency difference.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.