CN116754107B - Highly sensitive resonant pressure sensor with amplification structure and signal conditioning method - Google Patents

Abstract

The invention provides a high-sensitivity resonance pressure sensor with an amplifying structure and a signal conditioning method, relates to the technical field of resonance pressure sensors, and aims to realize a pressure sensor with higher reliability and stability and higher sensitivity and resolution, comprising a pressure sensitive film, a resonance detection structure and two single-stage amplifying structures; the resonance detection structure is provided with a resonance beam; two ends of a resonance beam of the resonance detection structure are respectively provided with the single-stage amplifying structure; the pressure sensitive film is used for sensing external pressure and generating deformation; the single-stage amplifying structure is provided with a plurality of anchor points connected with the pressure sensitive film and is used for amplifying and transmitting the deformation; the resonance detection structure is used for receiving deformation transmitted by the single-stage amplification structure and inducing the external pressure through harmonic waves. The pressure sensor has the advantages of higher sensitivity and resolution and noise reduction.

Description

Highly sensitive resonant pressure sensor with amplification structure and signal conditioning method

Technical field

The present invention relates to the technical field of resonant pressure sensors, and specifically to a high-sensitivity resonant pressure sensor with an amplification structure and a signal conditioning method.

Background technique

In modern engineering and science, pressure sensors play a key role in measuring and monitoring the pressure of various media.

However, traditional pressure sensors have certain limitations in sensitivity and resolution, which limit their performance and reliability in some application fields. With the development and application of microelectromechanical systems (MEMS) technology, silicon resonant pressure sensors have become a technology that has received widespread attention. Silicon resonant pressure sensors use changes in resonant frequency to measure external pressure and have the advantages of high accuracy, high sensitivity and fast response. However, in order to obtain higher sensitivity and resolution, sensor design needs to overcome some technical difficulties. Currently, existing silicon resonant pressure sensors generally have certain limitations in sensitivity and resolution. The low scale factor limits the sensor's ability to detect small pressure changes, affecting its application in high-precision pressure monitoring and control systems. In the existing technology, the patented high-sensitivity modal coupling silicon resonant pressure sensor and its pressure calculation method (Patent No.: CN114354024B) describes a method of converting the traditional frequency detection silicon resonant pressure sensor into a vibration amplitude type detection, To improve the sensitivity of the sensor. However, the design of this patent has some limitations. When the environmental interference is large, the amplitude is greatly affected by the environment, and the measurement accuracy will be affected, limiting the scope and feasibility of its practical application. On the other hand, after the sensor sensitivity is increased, new problems may be brought about, such as the signal frequency and amplitude becoming larger. Although the detection sensitivity is improved, it also brings problems such as signal distortion/increased noise.

Therefore, a design solution with higher reliability, more stability and less noise is needed to improve the sensitivity and resolution of the silicon resonant pressure sensor.

Contents of the invention

The object of the present invention is to provide a high-sensitivity resonant pressure sensor and a signal conditioning method with an amplification structure, which have higher reliability and stability, higher sensitivity and resolution, and smaller noise.

The embodiments of the present invention are implemented through the following technical solutions:

The present invention first provides a high-sensitivity resonant pressure sensor with an amplification structure, including a pressure-sensitive film, a resonant detection structure and two single-stage amplification structures; the resonant detection structure is provided with a resonant beam;

One of the single-stage amplification structures is provided at both ends of the resonant beam of the resonant detection structure;

The pressure-sensitive film is used to sense external pressure and produce deformation;

The single-stage amplification structure is provided with multiple anchor points connected to the pressure-sensitive film, and the single-stage amplification structure is used to amplify and transmit the deformation;

The resonance detection structure is used to receive the deformation transmitted by the single-stage amplification structure and induce the external pressure through harmonics.

Preferably, the single-stage amplification structure includes an input beam, an output beam, a lever beam and an anchor point; the input beam is an elastic structure;

The first end of the first input beam is provided with a first anchor point, the second end of the first input beam is connected to the first end of the first lever beam, and the first input beam and the first lever beam are perpendicular to each other;

The first end of the second input beam is provided with a second anchor point, the second end of the second input beam is connected to the first end of the second lever beam, and the second input beam and the second lever beam are perpendicular to each other;

The second end of the first lever beam and the second end of the second lever beam are connected through an output beam; the output beam is connected to the resonant beam;

A third anchor point and a fourth anchor point are respectively connected to the side of the first lever beam and the second lever beam close to the resonant beam.

Preferably, the output beam includes a first edge, a second edge and a third edge;

The first end of the first edge is connected to the second end of the first lever beam, and the first end of the third edge is connected to the second end of the second lever beam;

The second end of the first edge and the second end of the third edge are connected through the second edge, and the first edge and the third edge are parallel to each other; the second edge is connected to the Describe the resonant beam.

Preferably, the third anchor point and the fourth anchor point are respectively connected to the first lever beam and the second lever beam through a connecting rod.

Preferably, the resonance detection structure includes a resonant beam and multiple sets of resonant comb structures; the resonant comb structures are distributed on the beam body of the resonant beam.

Preferably, the number of the resonant comb tooth structures is two groups, and the two groups of the resonant comb tooth structures are symmetrical to each other about the central axis of the resonant beam.

Preferably, the resonant comb tooth structure includes a driving comb tooth and a vibrating comb tooth;

The driving comb teeth and the vibration comb teeth are both structures in which multiple comb teeth are vertically arranged on the base;

The comb tooth end of the driving comb tooth and the comb tooth end of the vibrating comb tooth are placed oppositely;

The base side of the vibration comb teeth is close to the resonant beam.

Preferably, the resonant beam is made of silicon material.

In order to solve the above problems, the present invention also provides a resonant pressure sensor signal conditioning method, which is applied to any of the above high-sensitivity resonant pressure sensors with an amplification structure, including the following steps:

The resonant sensor obtains the excitation signal;

Measure the resonant frequency of the resonant sensor through a resonant frequency detection circuit;

Convert the resonant frequency into an analog signal;

perform processing on the analog signal, the processing including amplification, filtering and linearization;

Convert the processed analog signal into a digital signal;

The digital signal is filtered, calibrated and data processed, and pressure information is extracted from the digital signal.

The technical solutions of the embodiments of the present invention have at least the following advantages and beneficial effects:

The present invention can achieve force amplification through a single-stage amplification structure, thereby enhancing the sensitivity and resolution of the pressure sensor;

The specific structural design of the single-stage amplification structure of the present invention can avoid excessive displacement that weakens the amplification effect while amplifying as much as possible;

The design of the resonant detection structure of the present invention can effectively avoid the interference of the co-resonant quality between the resonant beam and the pressure-sensitive film, helping to further improve the sensitivity and resolution of the resonant pressure sensor;

The resonance detection of the present invention will not be interfered by the environment, so the measurement stability and reliability are higher, it has wider application scenarios and scope, and it is highly feasible;

The present invention further provides a signal conditioning method, which can effectively avoid the problem of noise increase caused by increased sensor sensitivity;

The invention has reasonable design and simple structure, simplifies the hardware structure as much as possible while ensuring measurement accuracy, has high cost performance, and is easy to implement and popularize.

Description of the drawings

Figure 1 is a schematic structural diagram of a high-sensitivity silicon resonant pressure sensor with a lever amplification structure provided by an embodiment of the present invention;

Figure 2 is an equivalent model of a resonant beam and a pressure-sensitive membrane provided by an embodiment of the present invention;

Figure 3 is a schematic structural diagram of a single-stage amplification structure provided by an embodiment of the present invention;

Figure 4 is a schematic structural diagram of a resonance detection structure provided by an embodiment of the present invention;

Figure 5 is a schematic diagram of the principle of a resonant pressure sensor signal conditioning method provided by an embodiment of the present invention;

Icon: 100-single-stage amplification structure, 200-resonant detection structure, 300-pressure sensitive film, 101A-first anchor point, 101B-second anchor point, 102A-first input beam, 102B-second input beam, 103A -First lever beam, 103B-Second lever beam, 104A-Third anchor point, 104B-Fourth anchor point, 105-Output beam, 106-Connecting rod, 201-Vibration comb, 202-Driving comb, 203 -Resonant beam.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments These are some embodiments of the present invention, rather than all embodiments. The components of the embodiments of the invention generally described and illustrated in the figures herein may be arranged and designed in a variety of different configurations.

Example 1

Referring to Figures 1 to 4, a high-sensitivity resonant pressure sensor with an amplification structure includes a pressure-sensitive film 300, a resonant detection structure 200 and two single-stage amplification structures 100; the resonant detection structure 200 is provided with a resonant beam 203;

One of the single-stage amplification structures 100 is provided at both ends of the resonant beam 203 of the resonant detection structure 200;

The pressure-sensitive film 300 is used to sense external pressure and generate deformation;

The single-stage amplification structure 100 is provided with multiple anchor points connected to the pressure-sensitive film 300. The single-stage amplification structure 100 is used to amplify and transmit the deformation;

The resonance detection structure 200 is used to receive the deformation transmitted by the single-stage amplification structure 100 and induce the external pressure through harmonics.

The working principle of this embodiment is:

In traditional pressure sensors, the pressure-sensitive diaphragm will undergo deflection deformation when it is subjected to external loads. The deflection deformation of the pressure-sensitive diaphragm is the main sensing mechanism. However, due to the small size and limitations of the pressure diaphragm, the resulting The displacement signal is relatively small, thus limiting the sensitivity and resolution of the sensor.

In order to improve the sensitivity and resolution of the sensor, this embodiment introduces a single-stage amplification structure 100 . The function of the single-stage amplification structure 100 is to amplify the slight displacement generated when an external load acts on the pressure-sensitive film 300. When an external load acts on the pressure-sensitive film 300, the single-stage amplification structure 100 on the pressure-sensitive film 300 will undergo longitudinal displacement. , thereby causing the resonant beam 203 located at the end of the single-stage amplification structure 100 to be displaced. This displacement amplification effect improves the sensitivity of the force exerted on the resonant beam 203, that is, the scaling factor. Combined with the design of the resonant detection structure 200, by measuring the change in the frequency of the resonant beam 203, the external pressure on the pressure sensitive film 300 can be accurately reflected.

In particular, as shown in Figure 2, the second-order system composed of the resonant beam 203 of the pressure sensor and the pressure-sensitive film 300 is equivalent to a mechanical model. The entire system can be expressed as a second-order differential equation, in which the displacement of the resonant beam 203 is The output of the system, the external pressure is the input of the system. This differential equation describes the motion behavior of the resonant beam 203 under external pressure. In order to avoid interference from the co-resonant masses of the resonant beam 203 and the pressure-sensitive film 300, the equivalent mass model of the resonant beam 203 is designed to be perpendicular to the pressure-receiving direction of the pressure-sensitive film 300. When the sensor is working, the pressure-sensitive film 300 is subjected to a force in the vertical direction, forming a spring damping model of the equivalent mass of the pressure-sensitive film 300. The pressure effect is transmitted to the fixed end of the H-shaped double-end fixed resonant beam 203 through the silicon island, and the resonant beam The 203 equivalent mass spring damping model is in the horizontal direction, and theoretically there is almost no interference from co-vibrating masses.

In summary, through the design of the single-stage amplification structure 100 and the resonance detection structure 200, the silicon resonance pressure sensor with high sensitivity and accuracy provided in this embodiment can sense more accurately than the traditional design. Small pressure changes and convert them into measurable electrical signal output.

Example 2

This embodiment is based on the technical solution of Embodiment 1, and mainly further explains the single-stage amplification structure 100.

As a preferred solution of this embodiment, referring to Figure 3, the single-stage amplification structure 100 includes an input beam, an output beam 105, a lever beam and an anchor point; the input beam is an elastic structure;

The first end of the first input beam 102A is provided with a first anchor point 101A, the second end of the first input beam 102A is connected to the first end of the first lever beam 103A, and the first input beam 102A and the first lever beam 103A are perpendicular to each other. ;

The first end of the second input beam 102B is provided with a second anchor point 101B, the second end of the second input beam 102B is connected to the first end of the second lever beam 103B, and the second input beam 102B and the second lever beam 103B are perpendicular to each other. ;

The second end of the first lever beam 103A and the second end of the second lever beam 103B are connected through the output beam 105; the output beam 105 is connected to the resonant beam 203;

A third anchor point 104A and a fourth anchor point 104B are respectively connected to the side of the first lever beam 103A and the second lever beam 103B close to the resonant beam 203.

Further, the output beam 105 includes a first edge, a second edge and a third edge;

The first end of the first edge is connected to the second end of the first lever beam 103A, and the first end of the third edge is connected to the second end of the second lever beam 103B;

The second end of the first edge and the second end of the third edge are connected through the second edge, and the first edge and the third edge are parallel to each other; the second edge is connected to the The resonant beam 203 is described.

In addition, the third anchor point 104A and the fourth anchor point 104B are respectively connected to the first lever beam 103A and the second lever beam 103B through a connecting rod 106.

In this embodiment, the first input beam and the second input beam 102B are beam structures with certain elasticity, used to produce changes in the resonant frequency. The first input beam and the second input beam 102B pass through the first anchor points 101A and 101A respectively. The second anchor point 101B is connected to the pressure-sensitive membrane 300. When the pressure-sensitive membrane 300 is subjected to pressure, the input beam will be displaced or deformed due to the force;

The first lever beam 103A and the second lever beam 103B play a role in amplifying the deformation effect of sensitive components affected by pressure, such as the pressure-sensitive film 300 in this embodiment, and can respectively connect the corresponding first input beam 102A. The slight displacement or deformation of the second input beam 102B is amplified to increase the sensitivity and resolution of the sensor. Through the lever amplification effect, that is, the amplification ratio of the lever beam, the sensitivity of the force exerted on the resonant beam 203 can be improved. The first lever beam 103A and the second lever beam 103B are connected to the pressure sensitive film 300 through the third anchor point 104A and the fourth anchor point 104B respectively. This displacement is transmitted to the resonant beam 203 through the amplification effect of the lever beam, changing the resonant beam. The elastic stiffness of 203 leads to a change in the natural frequency of the resonator;

Finally, the output beam 105 is connected to the resonant beam 203 to realize the transmission of the pressure signal.

In order to design a microlever with the largest magnification possible, it is necessary to flexibly design the fulcrum and match the stiffness of the input beam, output beam, connecting rod and lever beam with each other. It can be expected that in order to achieve a flexible design, the bending stiffness of the connecting rod should be small, and a certain axial stiffness is also required to prevent its own displacement from being too large and weakening the amplification effect. The specific magnification factor can be achieved through force analysis.

Example 3

This embodiment is based on the technical solution of Embodiment 1. Referring to FIG. 4 , the resonance detection structure 200 is mainly further explained.

In this embodiment, the resonance detection structure 200 includes a resonant beam 203 and multiple sets of resonant comb structures; the resonant comb structures are distributed on the beam body of the resonant beam 203 .

As a further preferred solution, the number of the resonant comb-tooth structures is two groups, and the two groups of resonant comb-tooth structures are symmetrical to each other about the central axis of the resonant beam 203 .

In addition, the resonant comb tooth structure includes driving comb teeth 202 and vibrating comb teeth 201;

The driving comb teeth 202 and the vibration comb teeth 201 are both structures in which multiple comb teeth are vertically arranged on the base;

The comb tooth ends of the driving comb teeth 202 and the comb tooth ends of the vibrating comb teeth 201 are opposite to each other;

The base side of the vibration comb teeth 201 is close to the resonant beam 203 .

The resonant beam 203 is the main vibration element in the sensor. It responds to the effect of external pressure through changes in natural frequency. The resonant beam 203 adopts a slender beam-like structure and generally has high mechanical stiffness and low damping characteristics.

The vibration comb teeth 201 are mainly used to generate transverse harmonic vibration. This vibration acts on the resonant beam 203, causing it to be displaced, thereby causing the frequency of the resonant beam 203 to change. By controlling the excitation current frequency of the vibration comb teeth 201, the vibration state of the resonant beam 203 can be adjusted, thereby detecting and measuring changes in external pressure. The vibration comb teeth 201 are composed of fine metal electrodes and are fixed on a silicon substrate. They appear as a series of parallel finger-like structures, similar to the teeth of a comb. The design and size of the vibration comb teeth 201 determine the excitation frequency and amplitude of the resonant beam 203.

The driving comb teeth 202 are portions for applying driving force to the resonance beam 203 . It generates transverse harmonic vibration by applying an excitation current, and transfers energy to the resonant beam 203 to cause displacement and vibration. The function of the driving comb teeth 202 is to provide sufficient driving force so that the resonant beam 203 can be maintained in a suitable vibration state.

This embodiment can work in combination with the single-machine lever structure of Embodiment 2. When there is external pressure, the pressure-sensitive film 300 deforms and expands outward after being stressed. This deformation is transmitted through the silicon island structure and amplified to the input beam, which drives the input beam. The longitudinal displacement of the lever beam on the diaphragm is transmitted to the output beam 105 through the amplification of the lever beam. The output beam 105 is connected to the resonant beam 203, thereby changing the elastic stiffness of the resonant beam 203 and the natural frequency of the resonator. At the same time, The input beam also displaces as the pressure sensitive film 300 deforms, and the resistance of the varistor changes. At this time, the output voltage frequency is inconsistent with the natural frequency. When the closed-loop circuit feedbacks the excitation current frequency on the comb teeth, it is almost the resonator resonance. frequency, the resonator resonates. When the vibration reaches balance, the output voltage frequency is the natural frequency of the resonator. Within a certain pressure range, the natural frequency of the resonator has a stable proportional relationship with the pressure to be measured. Pressure detection can be achieved by detecting changes in the natural frequency.

In particular, under electrostatic driving, the resonant working mode of the resonator is that the resonant beams on the left and right sides dynamically balance reverse vibrations in the XOY plane, and the pickup resistor and the equivalent body silicon resistor form a Wheatstone bridge, and pass The bridge obtains the change in resistance of the piezoresistive material due to pressure changes, thereby achieving the purpose of detecting the resonant frequency of the resonator.

Example 4

This embodiment is based on the technical solution of Embodiment 1, and mainly further explains the material selection of the resonant beam 203.

As a preferred solution of this embodiment, the resonant beam 203 is made of silicon material. Because silicon has excellent mechanical properties and stable characteristics.

Example 5

This embodiment provides a resonant pressure sensor signal conditioning method, which is applied to the high-sensitivity resonant pressure sensor with an amplification structure provided in any of the above embodiments, including the following steps:

The resonant sensor obtains the excitation signal;

Measure the resonant frequency of the resonant sensor through a resonant frequency detection circuit;

Convert the resonant frequency into an analog signal;

perform processing on the analog signal, the processing including amplification, filtering and linearization;

Convert the processed analog signal into a digital signal;

The digital signal is filtered, calibrated and data processed, and pressure information is extracted from the digital signal.

Specifically, referring to Figure 5, the first step is to provide an excitation signal to the resonant sensor. The excitation signal is usually an AC signal of a specific frequency, which is provided to the sensor through a signal generator or drive circuit. Under the action of the excitation signal, the resonant sensor will generate Resonance effect, causing the resonant frequency to change;

Therefore, the resonant frequency detection circuit can be used to measure the resonant frequency of the sensor. The resonant frequency detection circuit can use, for example, a frequency counter or a PLL phase-locked loop circuit. This embodiment is preferably a PLL phase-locked loop circuit;

The resonant frequency measured above is a digital frequency signal, which needs to be converted into an analog signal related to the measured pressure. The converted analog signal is further processed, amplified, filtered and linearized through the analog signal processing module; this In one step, the amplification circuit can increase the signal amplitude to make it suitable for subsequent reading and processing. The filter circuit can remove noise and spurious signals to improve the quality of the signal. The linearization circuit can convert the nonlinear signal output by the sensor into a linear one. relationship to accurately measure pressure values;

The processed analog signal needs to be converted into a digital signal through analog-to-digital conversion for digital signal processing and storage. The analog signal is converted into a digital signal through an analog-to-digital converter (ADC), which contains the measurement information of the pressure sensor;

Finally, the digital signal is filtered, calibrated and data processed to extract the required pressure information.

The signal conditioning method of this embodiment can effectively solve the problem of increased noise caused by improving the sensitivity of the sensor itself.

The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims (6)

1. A high-sensitivity resonant pressure sensor with an amplification structure, characterized in that it includes a pressure-sensitive film (300), a resonance detection structure (200) and two single-stage amplification structures (100); the resonance detection structure (200) is configured There is a resonant beam (203); One of the single-stage amplification structures (100) is provided at both ends of the resonant beam (203) of the resonant detection structure (200); The pressure-sensitive film (300) is used to sense external pressure and generate deformation; The single-stage amplification structure (100) is provided with multiple anchor points connected to the pressure-sensitive film (300). The single-stage amplification structure (100) is used to amplify and transmit the deformation; The resonance detection structure (200) is used to receive the deformation transmitted by the single-stage amplification structure (100) and induce the external pressure through harmonics; The single-stage amplification structure (100) includes an input beam, an output beam (105), a lever beam and an anchor point; the input beam is an elastic structure; The first end of the first input beam (102A) is provided with a first anchor point (101A), the second end of the first input beam (102A) is connected to the first end of the first lever beam (103A), and the first input beam (103A) 102A) and the first lever beam (103A) are perpendicular to each other; The first end of the second input beam (102B) is provided with a second anchor point (101B), the second end of the second input beam (102B) is connected to the first end of the second lever beam (103B), and the second input beam (102B) is connected to the first end of the second lever beam (103B). 102B) and the second lever beam (103B) are perpendicular to each other; The second end of the first lever beam (103A) and the second end of the second lever beam (103B) are connected through an output beam (105); the output beam (105) is connected to the resonant beam (203 ); A third anchor point (104A) and a fourth anchor point (104B) are respectively connected to the side of the first lever beam (103A) and the second lever beam (103B) close to the resonant beam (203); The output beam (105) includes a first edge, a second edge and a third edge; The first end of the first edge is connected to the second end of the first lever beam (103A), and the first end of the third edge is connected to the second end of the second lever beam (103B); The second end of the first edge and the second end of the third edge are connected through the second edge, and the first edge and the third edge are parallel to each other; the second edge is connected to the The resonant beam (203); The third anchor point (104A) and the fourth anchor point (104B) are respectively connected to the first lever beam (103A) and the second lever beam (103B) through a connecting rod (106). 2. The high-sensitivity resonant pressure sensor with an amplification structure according to claim 1, characterized in that the resonant detection structure (200) includes a resonant beam (203) and multiple sets of resonant comb structures; the resonant comb structure The structures are distributed on the beam body of the resonant beam (203). 3. The high-sensitivity resonant pressure sensor with an amplification structure according to claim 2, characterized in that the number of the resonant comb structures is two groups, and the two groups of the resonant comb structures are related to the resonant beam ( 203)'s central axes are symmetrical to each other. 4. The high-sensitivity resonant pressure sensor with amplification structure according to claim 3, characterized in that the resonant comb tooth structure includes a driving comb tooth (202) and a vibration comb tooth (201); The driving comb teeth (202) and the vibration comb teeth (201) are both structures in which multiple comb teeth are vertically arranged on the base; The comb tooth ends of the driving comb teeth (202) and the comb tooth ends of the vibrating comb teeth (201) are opposite to each other; The base side of the vibration comb teeth (201) is close to the resonant beam (203). 5. The high-sensitivity resonant pressure sensor with amplification structure according to claim 1, characterized in that the resonant beam (203) is made of silicon material. 6. A resonant pressure sensor signal conditioning method, applied to the high-sensitivity resonant pressure sensor with an amplification structure according to any one of claims 1-5, characterized in that it includes the following steps: The resonant sensor obtains the excitation signal; Measure the resonant frequency of the resonant sensor through a resonant frequency detection circuit; Convert the resonant frequency into an analog signal; perform processing on the analog signal, the processing including amplification, filtering and linearization; Convert the processed analog signal into a digital signal; The digital signal is filtered, calibrated and data processed, and pressure information is extracted from the digital signal.