CN117928811A - Dual-mode resonant pressure sensor - Google Patents
Dual-mode resonant pressure sensor Download PDFInfo
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- CN117928811A CN117928811A CN202410056171.XA CN202410056171A CN117928811A CN 117928811 A CN117928811 A CN 117928811A CN 202410056171 A CN202410056171 A CN 202410056171A CN 117928811 A CN117928811 A CN 117928811A
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- 230000004807 localization Effects 0.000 claims abstract description 5
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- 239000012528 membrane Substances 0.000 claims description 4
- 238000007781 pre-processing Methods 0.000 claims description 3
- 238000005259 measurement Methods 0.000 abstract description 7
- 238000009530 blood pressure measurement Methods 0.000 abstract description 6
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- 238000009529 body temperature measurement Methods 0.000 description 2
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- 238000002955 isolation Methods 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 238000005452 bending Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
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Abstract
The invention provides a dual-mode resonant pressure sensor, which enables the same MEMS sensitive chip to realize full-range pressure measurement from medium and low vacuum to atmospheric pressure only through switching of a simple working mode. The sensor is measured in a pressure section larger than low vacuum through a plurality of (2 or more) single resonators or a resonant pressure sensor formed by matching a single resonator with a thermosensitive component, and the sensor has high-precision output characteristics at the part and can stably work in a wide temperature area. In the middle-low vacuum pressure section, a plurality of single resonators (not less than 2) are coupled together, and the coupling system works in a weak coupling state by adjusting the coupling rigidity, so that the sensor generates a mode localization phenomenon, thereby obtaining high sensitivity characteristic and realizing high sensitivity measurement of low vacuum pressure.
Description
Technical Field
The invention belongs to the field of MEMS pressure sensor design, and particularly relates to a dual-mode resonant pressure sensor.
Background
The traditional resonant pressure sensor is only suitable for pressure measurement above a low vacuum range (more than 0.5 kPa) under the influence of a strain mechanism, and has ultrahigh precision, but cannot measure the pressure in the low vacuum range. The existing full-range pressure sensor, namely measuring the pressure from atmospheric pressure to low-middle-low-vacuum or high-vacuum range, is generally based on the principle of thermal viscous damping or combined with a film and an ionization vacuum gauge to achieve the aim, the accuracy is generally low (not better than 10% of reading accuracy), the composition of the composite vacuum gauge is complex, and currently, researches on low-pressure measurement and high-accuracy normal-pressure measurement based on one sensor chip are fresh.
The shotty et al, in the incorporated patent 202010525596, "a full-range vacuum gauge and its test method," for the first time proposed that atmospheric pressure to high vacuum pressure measurement be achieved by a sensor chip. The method utilizes the multi-order modes of the resonators and combines the excitation-response relations of the resonators to realize the measurement of different pressure levels, and the method simply depends on damping related quantity-quality factor to represent the environmental pressure in a medium-low vacuum range.
The existing full-range vacuum pressure measurement scheme adopts two split sensors to measure and integrate and display through meters, so that the complexity of the system is increased, and the system integration is not facilitated. The range above the current measurement low vacuum pressure is mostly measured by a piezoresistive or damping type sensing component, so the precision is low and the sensitivity is limited. In addition, existing solutions can only work around 25 ℃, and no research or invention capable of adapting to lower temperatures (below 5 ℃) and higher temperatures (above 50 ℃) is found, which limits the application of the sensor to a certain extent.
Disclosure of Invention
The invention can realize the measurement from medium and low vacuum to atmospheric pressure by using the same MEMS sensitive chip only through the switching of a simple working mode. The pressure section above the medium and low vacuum is realized by a resonant pressure sensor formed by a plurality of (2 or more) single resonators or a single resonator and a thermosensitive component, and the sensor has high-precision output characteristics at the part and can stably work in the wide temperature area. In the middle and low vacuum pressure section, a plurality of resonators (not less than 2) are coupled together, and the coupling system is enabled to work in a weak coupling state by adjusting the coupling rigidity, and at the moment, the sensor generates a modal localization phenomenon, and researches have shown that the high sensitivity (or high resolution) characteristic can be obtained by the method, so that the high sensitivity measurement of the low vacuum pressure is realized.
The present invention provides a dual mode resonant pressure sensor comprising a resonator group comprising at least 2 individual resonators, wherein,
In the pressure section above the low vacuum, namely P is more than or equal to P 0, the single resonators of the resonator group are not coupled, the single resonators are respectively sensitive to pressure and respectively generate resonant frequency output quantities, and the pressure value to be measured at the temperature is obtained by simultaneously calculating the resonant frequency of some single resonators or calculating the frequency of one single resonator and the output value of a thermosensitive component;
In the middle and low vacuum range, namely P < P 0, the single resonators of the resonator group are weakly coupled, so that the resonator group generates a mode localization phenomenon, and at the moment, the amplitude information of each single resonator and the output value of the thermosensitive component are solved to obtain the measured value of the pressure to be measured at the temperature.
Further, the resonator group is a 2-degree-of-freedom coupled resonator based on electrostatic coupling achieved by electrostatic force; the two single resonators are fixed on the pressure membrane of the pressure sensor through anchor points, respective excitation and vibration pickup are realized through electrodes during operation, the coupling structure based on electrostatic force is in soft connection with the two single resonators through the two coupling electrodes, and the sensitivity of the sensor is adjusted by adjusting the strength of the electrostatic force and the number and the position of the anchor points of the coupling structure, so that the structures and the sizes of the two single resonators are identical.
Further, in the middle-low vacuum range, i.e., P < P 0, when the resonator group is operated in the weak coupling state, the measured value P of the pressure to be measured at the temperature T is obtained by the at least two single resonator amplitude information R 1 and R 2 and the thermosensitive member output value V:
P(T)＝g2(g1(R1,R2),V)
Wherein g 1 (·) represents a preprocessing function for the amplitude information R 1 and R 2, g 2 (·) is a functional relationship in which the amplitude related information g 1(R1,R2) and V are independent variables to represent the pressure P and the temperature T to be measured;
in the pressure section (P is more than or equal to P 0) above the low vacuum, the resonant frequencies f 1 and f 2 of at least two single resonators are calculated simultaneously or the frequency f i of one single resonator and the output value V of the thermosensitive component are calculated, so that the pressure value P to be measured at the temperature T is obtained as follows:
P (T) =h 1(f1,f2) or P (T) =h 2(fi, V
Wherein, h 1 (·) and h 2 (·) represent the functional relationship of the pressure P and the temperature T to be measured by taking the frequencies fi and V as independent variables.
The invention has the following beneficial technical effects:
The medium-low vacuum pressure section sensor works in a weak coupling mode and has high sensitivity characteristic; the pressure section sensor above the low vacuum works in a traditional resonance mode and has the characteristic of high precision. Can operate in a range from lower temperatures (less than 5 ℃) to higher temperatures (greater than 50 ℃). The pressure sensor can measure the pressure with high precision, and the performance of the pressure sensor is comparable to that of the traditional resonant pressure sensor.
Drawings
FIG. 1 is a cross-sectional view of a pressure sensor chip;
FIG. 2 is a 2-degree-of-freedom coupled resonator based on mechanical coupling achieved by a mechanical structure;
FIG. 3 is a 2-degree-of-freedom coupled resonator based on electrostatic coupling achieved by electrostatic forces;
FIG. 4 is a flow chart of an embodiment of a solution for resolving temperature based on a single resonator and temperature measurement component for a sensor P+.P 0;
FIG. 5 is a flow chart of an approach to resolving temperatures based on multiple (at least 2) individual resonators for sensor P+.gtoreq.P 0.
Detailed Description
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
A cross-sectional view of a dual mode resonant pressure sensor chip for example use is shown in fig. 1. The dual-mode resonant pressure sensor chip has a total 4-layer structure: cover plate layer 101, resonator layer 102, substrate layer 103, and isolation layer 104. A plurality of electrode lead holes 101.1 are distributed on the cover plate layer 101 and used for leading out signals of the resonator group 102.1, and a thermosensitive component 101.2 is arranged on the cover plate layer 101 and used for measuring the ambient temperature to assist in resolving pressure measured values at any temperature, so that the wide temperature area operation of the sensor is realized. The resonator group 102.1 is located in the resonator layer 102 and is connected to the pressure membrane 103.1 of the substrate layer 103 via an anchor point, the resonator group 102.1 includes at least 2 single resonators (such as double-ended clamped beam resonators), the sensitivity of each single resonator to pressure needs to be ensured to be different, and a vent hole 104.1 is formed on the isolation layer 104 for introducing the pressure to be measured into the pressure membrane 103.1.
Fig. 2 is a 2-degree-of-freedom coupled resonator based on mechanical coupling achieved by a mechanical structure, which is one specific implementation of the resonator group 102.1 in fig. 1. The coupled resonator consists of two structurally identical monolithic resonators 201.1 and 201.2 and a coupling structure 205. The individual resonators 201.1 and 201.2 are fixed to the pressure diaphragm 103.1 by means of anchor points 208, each individual resonator 201.1 and 201.2 having a tuning electrode 202 and 206, respectively. In operation, respective excitation and vibration pickup are achieved by the electrodes 203 and 207. When the resonant frequencies of the two single resonators 201.1 and 201.2 are identical, coupling is achieved by the coupling structure 205, and in order to make the sensor operate in the weak coupling mode within the set pressure range, the positions or the number of the anchor points 205.1 need to be adjusted so that the bending stiffness of the coupling structure 205 is far smaller than the stiffness of the single resonators 201.1 and 201.2. When the frequencies are not identical, the two will no longer operate in the coupled mode, but are equivalent to two separate resonators. Here the length or width of the resonators 201.1 and 201.2 are slightly different, so that the resonant frequencies at the pressure P 0 have a frequency difference of not less than 50 Hz.
In the middle-low vacuum range (P < P 0), if the resonance frequencies of the two single resonators 201.1 and 201.2 are inconsistent and cannot be coupled in practice, the two resonators can be coupled weakly by applying electrostatic force through the tuning electrodes 202 and 206, the sensitivity of the sensor is in inverse proportion to the coupling stiffness of the coupling structure 205, the sensor has the capability of high sensitivity and sensitive pressure by reducing the coupling stiffness of the coupling structure 205, namely weak coupling, and the amplitude information R 1 and R 2 of the resonators 201.1 and 201.2 and the output value V of the thermosensitive member 101.2 are calculated according to the following formula to obtain the measured value P of the pressure to be measured at the temperature T:
P(T)＝g2(g1(R1,R2),V)
Where g 1 (·) represents the preprocessing function for the amplitude information R 1 and R 2, g 2 (·) is the functional relationship representing the pressure to be measured P and the temperature T with the amplitude related information g 1(R1,R2) and V as independent variables, the specific form of which depends on the specific sensor.
In the pressure section above the low vacuum (P is more than or equal to P 0), the voltage of the tuning electrodes 202 and 206 is suspended, so that the two single resonators 201.1 and 201.2 can not be coupled all the time in the measuring range due to the discrepancy between the fundamental frequency and the sensitivity, the single resonators respectively sense the pressure to generate frequency output quantity, namely, the pressure output quantity is consistent with the working state of the traditional resonant pressure sensor, and the pressure value P to be measured under the temperature T can be obtained by simultaneously calculating the resonant frequencies f 1 and f 2 of the two single resonators or calculating the output value V of the frequency f i of one single resonator and the thermosensitive part 101.2:
P(T)＝h1(f1,f2)
Or (b)
P(T)＝h2(fi,V)
Wherein, h 1 (DEG) and h 2 (DEG) represent the functional relation of the pressure P to be measured and the temperature T by taking the frequencies fi and V as independent variables, the specific form depends on the specific sensor, and accordingly, the high-precision output of the pressure value in a wide temperature range (the lower temperature limit is lower than 5 ℃ and the upper temperature limit is higher than 50 ℃) can be realized.
Fig. 3 is a 2-degree-of-freedom coupled resonator based on electrostatic coupling achieved by electrostatic forces. This is an equivalent of fig. 2, which is another specific implementation of the resonator 102.1 in fig. 1. The individual resonators 301.1 and 301.2 are fixed to the pressure diaphragm 103.1 by anchor points 308, and in operation, the respective excitation and vibration pickup are achieved by electrodes 303 and 307. The coupling structure 305 is flexibly connected to the individual resonators 301.1 and 301.2 via two coupling electrodes 305.2, in which case the individual resonators 301.1 and 301.2 are identical in structure and size. When the medium and low vacuum pressure is measured (P < P 0), voltage is applied to the coupling electrode 305.2 to enable the two single resonators to be in soft connection with the coupling structure 305 through electrostatic force, the strength of the soft connection can be controlled through the voltage or the position and the number of anchor points 305.1, then the weak coupling of the two single resonators can be achieved through adjusting the voltage of the tuning electrodes 302 and 306, the electrode 304 is a suspended electrode, and the mode of high sensitivity induced by modal localization is operated only for forming a symmetrical structure with the coupling electrode 305.2. When the pressure section above the low vacuum is measured (P is more than or equal to P 0), the voltage of the coupling electrode 305.2 is adjusted to enable the potential difference between the coupling electrode 305.2 and the two single resonators to be zero, and the two single resonators work in the traditional resonant pressure sensor mode.
FIG. 4 is a flow chart of an embodiment of a solution for resolving temperature based on a single resonator and temperature measurement component for a sensor P+.P 0. After the power-on, the sensor works in the state of the traditional resonance pressure sensor and generates output V by measuring the temperature through the temperature measuring component, and if the pressure value P is more than or equal to P 0, the sensor continues to work in the traditional resonance sensitive mode and outputs the pressure value P; if the pressure value P < P 0, the voltages of the tuning electrode 202 or 206 and the tuning electrode 302 or 306 in fig. 2 and 3 are automatically adjusted to make the sensor change to work in the weak coupling resonance mode, and the pressure P to be measured when the temperature T is calculated according to the amplitude information R 1、R2 and the temperature information V is outputted, so that the measurement of the pressure of the sensor in the full range pressure range is realized by the reciprocating cycle.
FIG. 5 is a flow chart of an approach to resolving temperatures based on multiple (at least 2) individual resonators for sensor P+.gtoreq.P 0. After the power-on, the sensor works in a state of a traditional resonance pressure sensor, if the pressure value P is more than or equal to P 0, the sensor continues to work in a traditional resonance sensitive mode, and the environmental temperature T and the pressure P to be detected are calculated through the frequency information fusion of a plurality of single resonators and the pressure value P is output; if the pressure value P < P 0, the voltages of the tuning electrode 202 or 206 and the tuning electrode 302 or 306 in fig. 2 and 3 are automatically adjusted to make the sensor change to work in the weak coupling resonance mode, and the pressure P to be measured when the temperature T is calculated according to the amplitude information R 1、R2 and the temperature information V is outputted, so that the measurement of the pressure of the sensor in the full range pressure range is realized by the reciprocating cycle.
It will be readily appreciated by those skilled in the art that the foregoing description is merely a preferred embodiment of the invention and is not intended to limit the invention, but any modifications, equivalents, improvements or alternatives falling within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (3)
1. A dual mode resonant pressure sensor, characterized in that the dual mode resonant pressure sensor comprises a resonator group comprising at least 2 individual resonators, wherein,
In the pressure section above the low vacuum, namely P is more than or equal to P 0, the single resonators of the resonator group are not coupled, the single resonators are respectively sensitive to pressure and respectively generate resonant frequency output quantities, and the pressure value to be measured at the temperature is obtained by simultaneously calculating the resonant frequency of some single resonators or calculating the frequency of one single resonator and the output value of a thermosensitive component;
In the middle and low vacuum range, namely P < P 0, the single resonators of the resonator group are weakly coupled, so that the resonator group generates a mode localization phenomenon, and at the moment, the amplitude information of each single resonator and the output value of the thermosensitive component are solved to obtain the measured value of the pressure to be measured at the temperature.
2. The sensor of claim 1, wherein the resonator group is a 2-degree-of-freedom coupled resonator based on electrostatic coupling achieved by electrostatic forces; the two single resonators are fixed on the pressure membrane of the pressure sensor through anchor points, respective excitation and vibration pickup are realized through electrodes during operation, the coupling structure based on electrostatic force is in soft connection with the two single resonators through the two coupling electrodes, and the sensitivity of the sensor is adjusted by adjusting the strength of the electrostatic force and the number and the position of the anchor points of the coupling structure, so that the structures and the sizes of the two single resonators are identical.
3. The sensor of claim 1, wherein the measured value P of the pressure to be measured at the temperature T is calculated by the at least two individual resonator amplitude information R 1 and R 2 and the thermosensitive member output value V in the medium and low vacuum range, i.e., P < P 0, weak coupling:
P(T)＝g2(g1(R1,R2),V)
Wherein g 1 (·) represents a preprocessing function for the amplitude information R 1 and R 2, g 2 (·) is a functional relationship in which the amplitude related information g 1(R1,R2) and V are independent variables to represent the pressure P and the temperature T to be measured;
In the pressure section (P is more than or equal to P 0) above the low vacuum, the resonant frequencies f 1 and f 2 of at least two single resonators in the resonator group are solved simultaneously, or the frequency fi of one single resonator and the output value V of the thermosensitive component are solved, so that the pressure value P to be measured at the temperature T is obtained as follows:
P (T) =h 1(f1,f2) or P (T) =h 2(fi, V
Wherein, h 1 (·) and h 2 (·) represent the function relationship of the measured pressure P and the temperature T with the frequencies f 1、f2 and V as independent variables.
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