Pressure monitoring device and method based on nonlinear micro electro mechanical system resonator
By utilizing the cantilever beam amplitude jump response of a nonlinear microelectromechanical system resonator, the problem of insufficient sensitivity of MEMS sensors in medium and high vacuum environments is solved, achieving stability and high sensitivity in high vacuum pressure monitoring and simplifying the system structure.
Patent Information
- Application Number
- CN202511182309.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-22
- Publication Date
- 2025-11-14
AI Technical Summary
Existing MEMS resonant pressure sensors experience a sharp drop in sensitivity under medium to high vacuum conditions, failing to meet the requirements for accurate measurement. Existing solutions increase system complexity or power consumption, making it difficult to balance high accuracy with engineering practicality.
The nonlinear microelectromechanical system resonator, manufactured using single-crystal silicon or SOI wafers, responds to changes in environmental pressure by the amplitude jump of a cantilever beam in the nonlinear vibration region. It is forced into the nonlinear vibration region by using a DC bias voltage and a tunable AC drive signal, and outputs a binary signal by identifying the amplitude jump critical point.
It achieves stable, reliable, and highly sensitive pressure monitoring in high vacuum environments, avoids analog-to-digital conversion errors, has a simple and flexible structure, and eliminates the need for complex circuit modules.
Smart Images
Figure CN120947856A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of microelectromechanical systems (MEMS) technology, and in particular to a pressure device and method based on a nonlinear MEMS resonator. Background Technology
[0002] In high-end fields such as semiconductor manufacturing, particle physics experiments, and spacecraft vacuum systems, real-time monitoring of pressure to ensure safety thresholds is crucial for reliable system operation. These applications typically require precise binary state determination under medium-to-high vacuum conditions (pressure < 1 Torr). Measurement errors in pressure switches directly lead to decreased chip yield, spacecraft leakage risks, or distorted experimental data; therefore, developing high-precision, high-reliability vacuum pressure switches is of significant technological value. Microelectromechanical systems (MEMS) resonant pressure sensors, with their miniaturization, low power consumption, and ease of integration, have become ideal carriers for pressure switches. Their conventional operating principle relies on a linear damping dynamics model: pressure changes are determined by tracking the resonant frequency offset, exhibiting stability in industrial-grade low-vacuum environments (> 1 Torr). However, when applied to medium-to-high vacuum (< 1 Torr), the gas molecule density decreases sharply, causing the linear damping effect between the gas and the resonant structure to disappear. This makes it impossible to effectively extract the core performance indicator, the quality factor (Q value), resulting in a sharp drop in sensitivity and failing to meet the requirements for accurate measurement.
[0003] To address this issue, existing technologies have proposed piezoresistive MEMS switches, which convert pressure into resistance changes by embedding a piezoresistor in the sensitive area. While this improves sensitivity, it requires the integration of complex circuit modules, significantly increasing system power consumption and size, limiting its application in compact, low-power systems. Frequency comb technology has also been proposed, utilizing the nonlinear region of a resonator to generate a multi-harmonic frequency comb, theoretically enhancing signal stability. However, in practical applications, precisely maintaining the nonlinear operating point is necessary, and multi-channel phase-locked loops and spectrum analysis units are required to process harmonic signals, leading to an exponential increase in control system complexity. Structural optimization schemes have also been proposed, including irregular resonant cavity designs or piezoelectric-capacitive hybrid sensing, often resulting in compromises in manufacturing yield, temperature stability, or measurement range, making it difficult to balance high precision and engineering practicality. Therefore, there is an urgent need in this field for a pressure switch solution that is simple in structure, suitable for high vacuum, and stable and reliable. Summary of the Invention
[0004] The purpose of this invention is to address at least one deficiency in the prior art and to provide a pressure monitoring device and method based on a nonlinear microelectromechanical system resonator. This invention has a simple structure, is applicable to high vacuum, and provides stable and reliable pressure monitoring.
[0005] To achieve the above objectives, in a first aspect, the present invention provides a pressure switch based on a nonlinear microelectromechanical system resonator, manufactured using single-crystal silicon or SOI wafers through bulk micromachining or surface micromachining processes. The switch includes a silicon substrate, two anchor regions, a cantilever beam located within a vacuum cavity, a driving electrode, and a sensing electrode. The two anchor regions include a first anchor region and a second anchor region, both of which are fixedly disposed on the silicon substrate. A first end of the cantilever beam is rigidly connected to the first anchor region via a first anchor point, and a second end of the cantilever beam is rigidly connected to the second anchor region via a second anchor point. The main body of the cantilever beam is suspended above the silicon substrate. The driving electrode is disposed on one side of the cantilever beam in the width direction and has a first gap with the cantilever beam. The sensing electrode is disposed on the other side of the cantilever beam in the width direction and has a second gap with the cantilever beam, for detecting the vibration state of the cantilever beam. The driving electrode is configured to receive an AC driving signal to excite the cantilever beam into a nonlinear vibration region; the amplitude response of the cantilever beam in the nonlinear vibration region changes with the ambient pressure; the critical ambient pressure threshold at which the change occurs is negatively correlated with the frequency offset of the AC driving signal.
[0006] Preferably, the center points of the first anchor area and the second anchor area, as well as the center point of the cantilever beam, are located on a straight line parallel to the length direction of the cantilever beam, and the first anchor area and the second anchor area are symmetrically arranged about the straight line.
[0007] Preferably, the length-to-width ratio of the cantilever beam is greater than 10:1, and the length-to-thickness ratio is greater than 100:1.
[0008] Preferably, the driving electrode and the sensing electrode are made of conductive materials, including but not limited to doped polycrystalline silicon or metals.
[0009] Preferably, the critical environmental pressure threshold at which the transition occurs is negatively correlated with the frequency offset of the AC drive signal, as follows:
[0010] in, For the frequency offset of the AC drive signal, This is the pressure threshold.
[0011] Preferably, the vibration response of the cantilever beam is determined by the nonlinear effect of gas damping. When the change in ambient pressure reaches a critical pressure threshold, the amplitude of the cantilever beam jumps. The critical pressure threshold is controlled by programming by adjusting the frequency of the AC drive signal.
[0012] Preferably, the nonlinear effect is as follows:
[0013] in, For the mass of the cantilever beam, This is the gas damping coefficient. For the linear stiffness of the cantilever beam, These are the coefficients of a third nonlinearity. Let be the deflection of the cantilever beam. The frequency of the AC drive signal, The area of overlap between the cantilever beam and the electrode. The vacuum permittivity, and The bias voltage applied to the cantilever beam, This refers to the gap distance between the cantilever beam and the electrode.
[0014] Preferably, the programmed control range of the critical pressure threshold is 10 mTorr to 100 mTorr.
[0015] Secondly, the present invention also provides a pressure monitoring device based on a nonlinear microelectromechanical system resonator. The pressure monitoring device includes the pressure switch described in the first aspect, a frequency-adjustable signal source, a signal amplification module, and a signal analysis module. The output terminal of the frequency-adjustable signal source is connected to the driving electrode for applying a frequency-adjustable AC driving signal to the driving electrode. The input terminal of the signal amplification module is connected to the sensing electrode for converting the mechanical vibration of the cantilever beam into an amplified electrical signal. The input terminal of the signal analysis module is connected to the output terminal of the signal amplification module for real-time monitoring of the amplitude-frequency response characteristics of the cantilever beam, identifying the critical pressure threshold based on the amplitude jump point, and outputting a binary switch status signal.
[0016] Thirdly, the present invention also provides a pressure monitoring method based on a nonlinear microelectromechanical system resonator, the pressure monitoring method being based on the monitoring device described in the second aspect, comprising the following steps: An adjustable frequency AC drive signal is input to the drive electrode, while a DC bias voltage is applied to induce the cantilever beam into the nonlinear vibration region. The mechanical vibration of the cantilever beam is monitored by the sensing electrode and converted into an electrical signal. The electrical signal is amplified and filtered to extract the amplitude-frequency response characteristics. The amplitude-frequency response curve is monitored, and the frequency of the corresponding AC drive signal is recorded when the amplitude changes abruptly. Based on the negative correlation, the current environmental pressure threshold is calculated. If the measured environmental pressure value is greater than the environmental pressure threshold, an "on" signal is output; otherwise, a "off" signal is output. The frequency of the AC drive signal is dynamically adjusted so that the pressure threshold can be programmably set within the range of 10 mTorr to 100 mTorr.
[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention forces the cantilever beam into a nonlinear vibration region by applying a DC bias voltage and an adjustable frequency AC drive signal. It utilizes the amplitude jump effect to replace traditional linear frequency tracking, resulting in a simple structure suitable for high vacuum environments. Furthermore, by identifying the amplitude jump critical point, it directly outputs an "on / off" signal. If the measured environmental pressure is greater than the environmental pressure threshold, an "on" signal is output; otherwise, a "off" signal is output. This avoids the analog-to-digital conversion error chain, which helps improve the reliability, accuracy, and sensitivity of pressure monitoring. This invention only requires dynamic adjustment of the drive frequency to reset the pressure threshold, eliminating the complex conditioning circuits of piezoresistive schemes and the multiple phase-locked loops of frequency comb technology, resulting in a simple structure and high flexibility. Attached Figure Description
[0018] Figure 1 This is a structural diagram of a pressure switch based on a nonlinear microelectromechanical system resonator according to Embodiment 1 of the present invention; Figure 2 This is a structural diagram of a pressure monitoring device based on a nonlinear microelectromechanical system resonator according to Embodiment 2 of this aspect; Figure 3 This is a flowchart of a pressure monitoring method based on a nonlinear microelectromechanical system resonator according to Embodiment 3 of the present invention; Figure 4 This is the frequency response curve of Embodiment 2 of the present invention when the vacuum environment pressure reaches 270 mTorr; Figure 5 This is the frequency response curve of Embodiment 2 of the present invention when the vacuum environment pressure reaches 85 mTorr; Figure 6 This is a graph showing the relationship between frequency offset and vacuum pressure in Embodiment 2 of the present invention; Figure 7 This is a schematic diagram of the vibration state of the cantilever beam in Embodiment 1 of the present invention. Detailed Implementation
[0019] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.
[0020] Example 1 Please see Figure 1A pressure switch based on a nonlinear microelectromechanical system resonator, according to a preferred embodiment of the present invention, is manufactured using single-crystal silicon or SOI wafers through bulk micromachining or surface micromachining processes. It includes a silicon substrate, two anchor regions 1, a cantilever beam 2 located within a vacuum cavity, a driving electrode 3, and a sensing electrode 4. The two anchor regions include a first anchor region and a second anchor region, both of which are fixedly disposed on the silicon substrate. The first end of the cantilever beam 2 is rigidly connected to the first anchor region via a first anchor point, and the second end of the cantilever beam 2 is rigidly connected to the second anchor region via a second anchor point. The main body of the cantilever beam 2 is suspended above the silicon substrate. The driving electrode 3 is disposed on one side of the cantilever beam 2 in the width direction and has a first gap with the cantilever beam 2. The sensing electrode 4 is disposed on the other side of the cantilever beam 2 in the width direction and has a second gap with the cantilever beam 2, and is used to detect the vibration state of the cantilever beam 2. The driving electrode 3 is configured to receive an AC driving signal to excite the cantilever beam 2 into the nonlinear vibration region. For the vibration state of the cantilever beam 2, please refer to [link / reference needed]. Figure 7 The amplitude response of the cantilever beam 2 in the nonlinear vibration zone changes with the ambient pressure; the critical ambient pressure threshold at which the change occurs is negatively correlated with the frequency offset of the AC drive signal.
[0021] Preferably, the center points of the first anchor area and the second anchor area, as well as the center point of the cantilever beam 2, are located on a straight line parallel to the length direction of the cantilever beam 2, and the first anchor area and the second anchor area are symmetrically arranged about the straight line. In this embodiment, by symmetrically arranging the two anchor areas 1 with the cantilever beam 2, the stability and predictability of the beam vibration mode (such as the fundamental frequency bending mode) can be ensured, as well as accurate pressure threshold jumps can be achieved. Preferably, the length-to-width ratio of the cantilever beam 2 is greater than 10:1, and the length-to-thickness ratio is greater than 100:1.
[0022] In this embodiment, the length of the cantilever beam 2 is set to 500μm, the width to 25μm, and the thickness to 3μm.
[0023] Preferably, the driving electrode 3 and the sensing electrode 4 are made of conductive materials, including but not limited to doped polycrystalline silicon or metals, and optionally, metal silicides, etc. In this embodiment, by making the driving electrode 3 and the sensing electrode 4 conductive materials, it is beneficial for the driving electrode 3 to receive frequency-adjustable AC driving signals and DC bias voltages. The DC bias voltage is used to stabilize the operating point of the resonator, thereby allowing the cantilever beam 2 to enter the nonlinear vibration region; and it is also beneficial for the sensing electrode 4 to monitor the mechanical vibration of the cantilever beam 2 and convert the mechanical vibration into an electrical signal. Preferably, the critical environmental pressure threshold at which the transition occurs is negatively correlated with the frequency offset of the AC drive signal, as follows:
[0024] in, For the frequency offset of the AC drive signal, This is the pressure threshold.
[0025] Preferably, the vibration response of the cantilever beam 2 is determined by the nonlinear effect of gas damping. When the ambient pressure changes to a critical pressure threshold, the amplitude of the cantilever beam 2 jumps, and the critical pressure threshold is controlled by programming the frequency of the AC drive signal. In this embodiment, the programming control range is 10 mTorr to 100 mTorr.
[0026] Preferably, the nonlinear effect is as follows:
[0027] in, For the mass of the cantilever beam, This is the gas damping coefficient. For the linear stiffness of the cantilever beam, These are the coefficients of a third nonlinearity. Let be the deflection of the cantilever beam. The frequency of the AC drive signal, The area of overlap between the cantilever beam and the electrode. The vacuum permittivity, and The bias voltage applied to the cantilever beam, This refers to the gap distance between the cantilever beam and the electrode. When the vacuum pressure changes to a critical threshold, the change in the gas damping coefficient causes a change in the beam's deflection, resulting in a sudden change in the beam's vibration state (such as a sudden transition from high-amplitude oscillation to stillness). This sudden change generates a binary switch signal, which triggers an "on / off" state transition when the pressure exceeds the threshold, enabling precise monitoring of medium-to-high vacuum environments.
[0028] This embodiment forces the cantilever beam into the nonlinear vibration region by applying a DC bias voltage and an adjustable frequency AC drive signal. It utilizes the amplitude jump effect to replace traditional linear frequency tracking, resulting in a simple structure suitable for high vacuum environments. Furthermore, by identifying the amplitude jump critical point, it directly outputs an "on / off" signal. If the measured environmental pressure value is greater than the environmental pressure threshold, an "on" signal is output; otherwise, a "off" signal is output. This avoids the analog-to-digital conversion error chain, which helps improve the reliability, accuracy, and sensitivity of pressure monitoring. This invention only requires dynamic adjustment of the drive frequency to reset the pressure threshold, eliminating the complex conditioning circuit of the piezoresistive scheme and the multiple phase-locked loops of the frequency comb technology, resulting in a simple structure and high flexibility.
[0029] Example 2 Please see Figure 2 This invention also provides a pressure monitoring device based on a nonlinear microelectromechanical system resonator. The pressure monitoring device includes the pressure switch described in Embodiment 1, a frequency-adjustable signal source, a signal amplification module, and a signal analysis module. The output terminal of the frequency-adjustable signal source is connected to the driving electrode and is used to apply a frequency-adjustable AC driving signal to the driving electrode. The input terminal of the signal amplification module is connected to the sensing electrode and is used to convert the mechanical vibration of the cantilever beam into an amplified electrical signal. The input terminal of the signal analysis module is connected to the output terminal of the signal amplification module and is used to monitor the amplitude-frequency response characteristics of the cantilever beam in real time, identify the critical pressure threshold based on the amplitude jump point, and output a binary switch status signal.
[0030] In this embodiment, the adjustable signal source and signal analysis module are integrated into the network analyzer, and the signal amplification module is a signal amplifier. The network analyzer is a Keysight E5071C, and the signal amplifier is a Stanford Research Systems Model SR445A.
[0031] This embodiment conducts an experiment based on the above-described device. The experimental structure is as follows: Figure 4-5 As shown in the figure, the frequency response curve in the nonlinear region exhibits a typical upward jump phenomenon. When the cantilever beam resonator is subjected to forward and reverse frequency sweeps under different pressure conditions (270 mTorr, 85 mTorr), exceeding the threshold frequency causes a jump in amplitude, and the oscillation of the cantilever beam changes from low amplitude to high amplitude. Since the frequency response curve differs under different environmental pressures, and the pressure threshold varies under different input signal frequencies, the pressure threshold of the pressure switch can be adjusted by regulating the input signal frequency. Please refer to [link / reference]. Figure 6As shown, when the ambient pressure is greater than the 100 mTorr pressure threshold, the pressure switch operates in a low-amplitude "off" state. When the ambient pressure is less than the 100 mTorr pressure threshold, the pressure switch operates in a high-amplitude "on" state. The pressure switch can detect minute pressure changes, achieving binary detection of the "on / off" state.
[0032] It should also be noted that the pressure switch in the pressure monitoring device proposed in this embodiment is based on the pressure switch proposed in Embodiment 1. Therefore, the options proposed in Embodiment 1 are also applicable to this application, and will not be repeated here.
[0033] Example 3 Please see Figure 3 This invention also provides a pressure monitoring method based on a nonlinear microelectromechanical system resonator, comprising the following steps: S1: Input an adjustable frequency AC drive signal to the drive electrode, and simultaneously apply a DC bias voltage to cause the cantilever beam to enter the nonlinear vibration region; S2: Monitor the mechanical vibration of the cantilever beam through the sensing electrode and convert the mechanical vibration into an electrical signal; S3: Amplify and filter the electrical signal to extract the amplitude-frequency response characteristics; S4: Monitor the amplitude-frequency response curve, and record the frequency of the corresponding AC drive signal when the amplitude jumps; S5: Calculate the current environmental pressure threshold based on the negative correlation. If the measured environmental pressure value is greater than the environmental pressure threshold, output an "on" signal; otherwise, output a "off" signal; S6: Dynamically adjust the frequency of the AC drive signal so that the pressure threshold can be programmably set within the range of 10mTorr to 100mTorr.
[0034] The pressure monitoring method proposed in this embodiment is based on the pressure monitoring device described in Embodiment 2 and the pressure switch described in Embodiment 1. Therefore, the options proposed in Embodiments 1 and 2 are also applicable to this embodiment. To avoid repetition, they will not be described again here.
[0035] Obviously, the embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.
Claims
1. A pressure switch based on a nonlinear microelectromechanical system resonator, manufactured using single-crystal silicon or SOI wafers through bulk micromachining or surface micromachining processes, characterized in that... The device includes a silicon substrate, two anchor regions (1), a cantilever beam (2) located in a vacuum cavity, a driving electrode (3), and a sensing electrode (4). The two anchor regions include a first anchor region and a second anchor region, and both the first anchor region and the second anchor region are fixedly disposed on the silicon substrate. The first end of the cantilever beam (2) is rigidly connected to the first anchor region through a first anchor point, and the second end of the cantilever beam (2) is rigidly connected to the second anchor region through a second anchor point. The main body of the cantilever beam (2) is suspended above the silicon substrate. The driving electrode (3) is disposed on one side of the width direction of the cantilever beam (2) and has a first gap with the cantilever beam (2). The sensing electrode (4) is disposed on the other side of the width direction of the cantilever beam (2) and has a second gap with the cantilever beam (2), and is used to detect the vibration state of the cantilever beam (2). The driving electrode (3) is configured to receive an AC driving signal to excite the cantilever beam (2) into a nonlinear vibration region; the amplitude response of the cantilever beam (2) in the nonlinear vibration region changes with the change of the surrounding environmental pressure; the critical environmental pressure threshold at which the change occurs is negatively correlated with the frequency offset of the AC driving signal.
2. A pressure switch based on a nonlinear microelectromechanical system resonator according to claim 1, characterized in that, The center points of the first anchor area and the second anchor area, as well as the center point of the cantilever beam (2), are located on a straight line parallel to the length direction of the cantilever beam (2), and the first anchor area and the second anchor area are symmetrically arranged about the straight line.
3. A pressure switch based on a nonlinear microelectromechanical system resonator according to claim 1, characterized in that, The length-to-width ratio of the cantilever beam (2) is greater than 10:1, and the length-to-thickness ratio is greater than 100:
1.
4. A pressure switch based on a nonlinear microelectromechanical system resonator according to any one of claims 1-3, characterized in that, The driving electrode (3) and the sensing electrode (4) are made of conductive materials, including but not limited to doped polycrystalline silicon or metals.
5. A pressure switch based on a nonlinear microelectromechanical system resonator according to claim 4, characterized in that, The critical environmental pressure threshold at which the transition occurs is negatively correlated with the frequency offset of the AC drive signal, as follows: in, For the frequency offset of the AC drive signal, This is the pressure threshold.
6. A pressure switch based on a nonlinear microelectromechanical system resonator according to claim 1, characterized in that, The vibration response of the cantilever beam (2) is determined by the nonlinear effect of gas damping. When the change in ambient pressure reaches the critical pressure threshold, the amplitude of the cantilever beam (2) jumps. The critical pressure threshold is controlled by programming by adjusting the frequency of the AC drive signal.
7. A pressure switch based on a nonlinear microelectromechanical system resonator according to claim 6, characterized in that, The nonlinear effect is as follows: in, For the mass of the cantilever beam, This is the gas damping coefficient. For the linear stiffness of the cantilever beam, These are the coefficients of a third nonlinearity. Let be the deflection of the cantilever beam. The frequency of the AC drive signal, The area of overlap between the cantilever beam and the electrode. The vacuum permittivity, and The bias voltage applied to the cantilever beam, This refers to the gap distance between the cantilever beam and the electrode.
8. A pressure switch based on a nonlinear microelectromechanical system resonator according to claim 6, characterized in that, The programmed control range of the critical pressure threshold is 10 mTorr to 100 mTorr.
9. A pressure monitoring device based on a nonlinear microelectromechanical system resonator, characterized in that, The pressure monitoring device includes a pressure switch, a frequency-adjustable signal source, a signal amplification module, and a signal analysis module as described in any one of claims 1-8. The output end of the frequency-adjustable signal source is connected to the driving electrode (3) and is used to apply a frequency-adjustable AC driving signal to the driving electrode (3). The input end of the signal amplification module is connected to the sensing electrode (4) and is used to convert the mechanical vibration of the cantilever beam (2) into an amplified electrical signal. The input end of the signal analysis module is connected to the output end of the signal amplification module and is used to monitor the amplitude-frequency response characteristics of the cantilever beam (2) in real time, identify the critical pressure threshold based on the amplitude jump point, and output a binary switch status signal.
10. A pressure monitoring method based on a nonlinear microelectromechanical system resonator, characterized in that, The pressure monitoring method, based on the monitoring device of claim 9, includes the following steps: An adjustable frequency AC drive signal is input to the drive electrode, while a DC bias voltage is applied to induce the cantilever beam into the nonlinear vibration region. The mechanical vibration of the cantilever beam is monitored by the sensing electrode and converted into an electrical signal. The electrical signal is amplified and filtered to extract the amplitude-frequency response characteristics. The amplitude-frequency response curve is monitored, and the frequency of the corresponding AC drive signal is recorded when the amplitude changes abruptly. Based on the negative correlation, the current environmental pressure threshold is calculated. If the measured environmental pressure value is greater than the environmental pressure threshold, an "on" signal is output; otherwise, a "off" signal is output. The frequency of the AC drive signal is dynamically adjusted so that the pressure threshold can be programmably set within the range of 10 mTorr to 100 mTorr.