WO2023045580A1 - Pt symmetry principle-based mems resonant magnetic field sensor and method of using same - Google Patents

Abstract

A PT symmetry principle-based MEMS resonant magnetic field sensor and a method of using same. The MEMS resonant magnetic field sensor comprises a left resonator and a right resonator, and the left resonator and the right resonator are of a left-right mirror symmetrical structure and are connected to each other by means of a coupling spring (7); the left resonator and the right resonator are each externally connected to a damping modulation circuit, the damping modulation circuit controls equivalent damping of the left resonator and the right resonator to be equal in magnitude and to have opposite signs, and a PT symmetric resonator system is formed. The MEMS resonant magnetic field sensor further comprises a left direct-current power source (12) and a right direct-current power source (13), the left direct-current power source (12) is loaded on the left resonator to form a direct current flowing from top to bottom, and the right direct-current power source (13) is loaded on the right resonator to form a direct current flowing from bottom to top; under the action of Lorentz force, a coupling coefficient between the left resonator and the right resonator is changed, and a resonant frequency of the PT symmetric resonator system is further changed; by means of damping magnitude modulation, the PT symmetric resonator system operates at singular points having equal coupling coefficients and loss parameters, and the sensitivity of the sensor is greatly improved.

Description

A MEMS resonant magnetic field sensor based on PT symmetry principle and its application method technical field

The invention belongs to the technical field of micro-electromechanical (MEMS), discloses the application of space mirror-time inversion (PT) symmetry principle in micro-electromechanical machinery, and specifically relates to a MEMS resonant magnetic field sensor based on the PT symmetry principle and its use method.

Background technique

Magnetic field sensors are widely used in many fields such as industry, automobile, medical treatment, and home appliances. They are the core components of components such as electronic compasses and information read-write heads.

Magnetic field sensors usually use permanent magnet force, Lorentz force, Hall effect, etc. to detect the magnitude of the magnetic field. In 2003, Leichle TG (Leichle T C, Ye W, Allen M G.A Sub-μW Micromachined Magnetic Compass[C]IEEE Conference on SENSORS.Kyoto, Japan, 2003:514-517) and others proposed a magnetic field with an intercalated finger structure The sensor deforms the structure of the driving finger through the permanent magnet under the magnetic force, and then detects the direction of the magnetic field. However, the magnetic field sensor based on the permanent magnet is difficult to process and poor in consistency, which is not conducive to mass production. In 2012, Chen Jie (Chen Jie. Research on MEMS magnetic field sensors with two structures [J]. Journal of Sensing Technology, 2012(12): 1648-1652.) and others proposed a cantilever beam structure and a double-ended solid The magnetic field sensor of the beam structure, both of them change the resonant frequency through the action of the Lorentz force on the current-carrying wire on the beam, and then detect the magnitude of the magnetic field. In 2012, Chen Ting (Chen Ting. Magnetic induction intensity measurement device based on Hall effect, CN202522689U[P].) and others proposed a magnetic field sensor based on Hall effect, using Hall elements to pass current in one direction, and the other Applying a magnetic field in one direction will generate a voltage in the third direction to measure the magnetic induction intensity. The above-mentioned traditional magnetic field sensor based on Lorentz force and Hall effect has low sensitivity and poor detection accuracy.

In 1998, Bender and Boettcher (Bender C M, Boettcher S, Meisinger P N. PT-Symmetric Quantum Mechanics [J]. Journal of Mathematical Physics, 1998, 40 (5).) proposed a special series of space mirror-time mirror The (PT) symmetric Hamiltonian is derived, the PT symmetric system is theoretically studied, and it is pointed out that in addition to the Hermitian system, the PT symmetric system can also obtain real number solutions. Then, this theory was extended to many fields such as optics, mechanics, electricity and so on. 2014 Jan Wiersig(Wiersig J.Enhancing the Sensitivity of Frequency and Energy Splitting Detection by Using Exceptional Points:Application to Microcavity Sensors for Single-Particle Detection[J].Phys.rev.lett,2014,112-3901.1:2 203901.5.) and others proposed that the PT symmetrical system is biased near the singular point, and the external parameters exert perturbation on the system, which will cause the frequency split of the system, and the sensor designed by this principle is extremely sensitive. Therefore, how to integrate the principle of PT symmetry into the design and production of sensors has become an urgent research and development issue in the field of micro-electromechanical technology.

Contents of the invention

The present invention is aimed at the problems in the prior art, and in order to greatly improve the sensitivity of the sensor, it proposes a MEMS resonant magnetic field sensor based on the principle of PT symmetry and its use method, including a left resonator and a right resonator. The left resonator and the right resonator have a left and right mirror symmetrical structure, and are connected by coupling springs; the left resonator and the right resonator are respectively externally connected to a damping modulation circuit, and the damping modulation circuit controls the equivalent damping of the left resonator and the right resonator equal and opposite in sign to form a PT symmetrical resonator system; it also includes a left DC power supply and a right DC power supply, the left DC power supply is loaded on the left resonator to form a top-down DC current, and the right DC power supply is loaded on the On the right resonator, a bottom-up DC current is formed. Under the action of the Lorentz force, the PT symmetrical resonator system works at the singular point where the coupling coefficient and the loss parameter are equal through the modulation of the damping value, which greatly improves the sensor performance. sensitivity.

In order to achieve the above object, the technical solution adopted by the present invention is: a MEMS resonant magnetic field sensor based on the principle of PT symmetry, including a left resonator and a right resonator, and the left and right resonators are left and right mirror symmetrical structures, And connected by a coupling spring; wherein, the left resonator and the right resonator are respectively externally connected to a damping modulation circuit, and the damping modulation circuit controls the equivalent damping of the left resonator and the right resonator to be equal in size and opposite in sign, forming a PT symmetrical resonator system;

It also includes a left DC power supply and a right DC power supply, the left DC power supply is loaded on the left resonator to form a top-down DC current, and the right DC power supply is loaded on the right resonator to form a bottom-up DC current Current, under the action of Lorentz force, the coupling coefficient between the left and right resonators changes, thereby changing the resonant frequency of the PT symmetrical resonant system, through the modulation of the damping size, the PT symmetrical resonator system works at the coupling coefficient and loss parameters equal singularity.

As an improvement of the present invention, the left resonator includes a left resonant finger, a left drive finger and a left detection finger, the right resonator includes a right resonant finger, a right drive finger and a right detection finger, and the left resonator The upper and lower ends of the finger and the right resonant finger are fixed on the sensor substrate, and the rest are suspended above the substrate; the left drive finger, left detection finger, right drive finger, and right detection finger are fixed on the sensor substrate On the bottom, the coupling spring is suspended above the sensor substrate.

As an improvement of the present invention, a left drive port is set between the left drive finger and the left resonant finger, a left detection port is set between the left detection finger and the left resonant finger; The right drive port is set between the right detection finger and the right resonant finger, and the right detection port is set between the right detection finger and the right resonant finger. When the magnetic field in the surface is applied, the coupling coefficient between the left and right resonators is changed by the Lorentz force on the left resonant finger and the right resonant finger.

In order to achieve the above object, the technical solution adopted in the present invention is: a method for using a MEMS resonant magnetic field sensor based on the principle of PT symmetry, comprising the following steps:

S1, respectively control the left resonator and the right resonator through the damping modulation circuit, so that the equivalent damping of the left resonator and the right resonator is always kept equal in size and opposite in sign, forming a PT symmetrical resonator system;

S2, turning on the left DC power supply and the right DC power supply, so that the left resonant finger in the left resonator forms a top-down DC power supply, and the right resonant finger in the right resonator forms a bottom-up DC power supply;

S3, when there is a magnetic field perpendicular to the paper surface, the left resonant finger and the right resonant finger are subjected to the Lorentz force, which changes the coupling coefficient between the left and right resonators and changes the resonant frequency of the PT symmetrical resonant system;

S4, make the PT symmetrical resonator system work at a singular point where the coupling coefficient is equal to the loss parameter through damping size modulation, and detect the change of the resonant frequency of the PT symmetrical resonant system to measure the magnetic field.

Compared with the prior art, the MEMS resonant magnetic field sensor based on the principle of PT symmetry proposed by the present invention, because the PT symmetric resonator system works at the singular point, any perturbation will cause a great change in the resonance frequency, therefore, this The invented MEMS resonant magnetic field sensor has extremely high sensitivity, simple structure, convenient operation, higher cost performance, and is more suitable for mass production in the field of micro-electromechanical systems.

Description of drawings

Fig. 1 is the top view of the structural section of the MEMS resonant magnetic field sensor based on the principle of PT symmetry in the present invention;

Fig. 2 is the spring equivalent model diagram of the MEMS resonant magnetic field sensor based on the PT symmetry principle of the present invention;

Figure 3 is a diagram of an equivalent spring model based on a DP (Diabolical Point) resonant magnetic field sensor;

Fig. 4 is a comparison diagram of the normalized resonance frequency change between the PT symmetrical resonance system and the DP resonance system in Embodiment 1 of the present invention;

Fig. 5 is the sensitivity contrast diagram of PT symmetrical resonant system and DP resonant system in embodiment 1 of the present invention;

FIG. 6 is a structure diagram of the damping modulation circuit of the present invention.

Among them, 1. left resonant finger, 2. left drive finger, 3. left detection finger, 4. right resonant finger, 5. right drive finger, 6. right detection finger, 7. coupling spring, 8 .Left drive port, 9. Left detection port, 10. Right drive port, 11. Right detection port, 12. Left DC power supply, 13. Right DC power supply, 14. Signal input terminal, 15. Signal output terminal, 16. Electromechanical Conversion control circuit, 17. gain control circuit, 18. phase control circuit, 19 motor conversion control circuit.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

Example 1

A MEMS resonant magnetic field sensor based on the principle of PT symmetry, as shown in Figure 1, the left resonator is composed of the left resonant finger 1, the left drive finger 2, and the left detection finger 3; the right resonant finger 4, the right The driving finger 5 and the right detecting finger 6 form a right resonator, and the left resonator and the right resonator have a left-right mirror symmetrical structure and are connected together by a coupling spring 7 . The upper and lower ends of the left resonant finger 1 and the right resonant finger 4 are fixed on the sensor substrate, and the rest are suspended above the substrate. The left driving finger 2, the left detecting finger 3, the right driving finger 5, and the right detecting finger 6 are fixed on the sensor substrate, and the coupling spring 7 is suspended above the substrate.

Wherein, the left resonator and the right resonator are respectively externally connected with a damping modulation circuit, and the damping modulation circuits on the left and right sides control the damping of the left resonator and the right resonator respectively; it also includes a left DC power supply 12 and a right DC power supply 13. When the power is turned on, The left DC power supply 12 is loaded on the left resonator to form a top-down DC current, and the right DC power supply 13 is loaded on the right resonator to form a bottom-up DC current.

When using the MEMS resonant magnetic field sensor based on the principle of PT symmetry in this embodiment:

(1) First, the left resonator and the right resonator are respectively controlled through the damping modulation circuit, so that the equivalent damping c of the left resonator and the right resonator are always kept equal in size and opposite in sign, forming a PT symmetrical resonator system;

(2) Then, turn on the left DC power supply 12 and the right DC power supply 13, so that the left resonant finger 1 in the left resonator forms a DC power supply from top to bottom, and the right resonant finger 4 in the right resonator forms a self-contained DC power supply. Down-to-up DC power supply;

(3) When there is a magnetic field perpendicular to the paper surface, the left resonant finger 1 and the right resonant finger 4 are affected by the Lorentz force, which makes the coupling coefficient μ between the left and right resonators change, changing the PT symmetrical resonant system Resonant frequency;

(4) The PT symmetric resonator system works at the singular point where the coupling coefficient and the loss parameter are equal through the modulation of the damping value, and the change of the resonant frequency of the PT symmetric resonator system is detected to measure the magnitude of the magnetic field.

谐振器损耗参数

左右谐振器间耦合参数为μ＝k _c/k，PT对称奇异点有γ＝μ。该实施例中，谐振器等效弹性系数k＝1400N/m，等效质量m＝5×10 ^-10kg，等效阻尼系数c＝8.36×10 ^-7N·s/m，则固有谐振频率ω ₀＝1.67MHz(对应f ₀＝266.32kHz)，损耗参数γ＝9.99×10 ^-4，耦合等效弹性系数k _c＝1.40N/m。 As shown in Figure 2, the spring equivalent model diagram of the MEMS resonant magnetic field sensor based on the principle of PT symmetry, where k is the equivalent elastic coefficient of the resonator, m is the equivalent mass of the resonator, and c is the equivalent damping coefficient of the resonator, k _c is the equivalent elastic coefficient of left and right resonator coupling, then the natural resonant frequency of the resonator is

Resonator Loss Parameters

The coupling parameter between the left and right resonators is μ=k _c /k, and the PT symmetrical singular point has γ=μ. In this embodiment, the resonator equivalent elastic coefficient k=1400N/m, equivalent mass m=5×10 ^-10 kg, equivalent damping coefficient c=8.36×10 ^-7 N·s/m, then the natural resonance frequency ω ₀ =1.67MHz (corresponding to f ₀ =266.32kHz), loss parameter γ=9.99×10 ^-4 , coupling equivalent elastic coefficient k _c =1.40N/m.

Figure 3 is a diagram of an equivalent spring model based on a DP (Diabolical Point) resonant magnetic field sensor. Compared with Figure 2, it can be seen that the left resonator and the right resonator have a mirror-image symmetrical structure and are connected by a coupling spring, but there is no damping control system, and the rest of the parameters are consistent with those of the PT symmetrical resonance system.

进行归一化。当磁场产生的洛伦兹 力使左右谐振器之间的等效弹性系数由kc变为k _c+Δk _c，即耦合系数μ发生微小变化δ＝Δk _c/k _c时，PT对称谐振系统的归一化谐振频率变化远大于DP谐振系统的，即如图4所示。因此PT对称系统对磁场产生的洛伦兹力造成的耦合系数微扰的灵敏度也远高于DP谐振式磁场传感器，如图5所示。 Use the resonator natural frequency for the system resonant frequency

to normalize. When the Lorentz force generated by the magnetic field makes the equivalent elastic coefficient between the left and right resonators change from kc to _kc + _Δkc , that is, when the coupling coefficient μ changes slightly δ= _Δkc / _kc , the PT symmetrical resonant system The normalized resonant frequency variation is much larger than that of the DP resonant system, as shown in Figure 4. Therefore, the sensitivity of the PT symmetrical system to the coupling coefficient perturbation caused by the Lorentz force generated by the magnetic field is much higher than that of the DP resonant magnetic field sensor, as shown in Figure 5.

To sum up, at the singular point of the PT symmetric resonator system, any perturbation will cause a great change in the resonance frequency, therefore, the MEMS resonant magnetic field sensor of the present invention has extremely high sensitivity.

Example 2

The difference between this embodiment and Embodiment 1 is that the left drive port 8 is drawn between the left driving finger 2 and the left resonant finger 1, and the left detection port 9 is drawn between the left detection finger 3 and the left resonant finger 1. The right drive port 10 is drawn between the right drive finger 5 and the right resonant finger 4, and the right detection port 11 is drawn between the right detection finger 6 and the right resonant finger 4. The left drive port 8 and the right drive port 10 are respectively connected to the damping modulation circuit.

As shown in FIG. 6 , the damping modulation circuit is composed of an input port 14 , an output port 15 , an electromechanical conversion control circuit 16 , a motor conversion control circuit 17 , a gain control circuit 18 , and a phase control circuit 19 . The input port 14 is connected with the left detection port 9/right detection port 11, and the output port 15 is connected with the left drive port 8/right drive port 10. The output of the resonator is converted into an appropriate electrical signal by the electromechanical conversion control circuit 16, and then the The electric signal is subjected to gain control and phase control, and finally converted into a damping modulation control signal by the motor conversion control circuit 17 and fed back to the resonator. The positive and negative values of the equivalent damping are adjusted by the phase controller 19. When the feedback signal is in phase with the resonator vibration signal, the system exhibits negative damping; when the feedback signal and the resonator vibration signal are out of phase, the system exhibits positive damping. The size of the damping is adjusted jointly by the gain controller 18 and the phase controller 19 .

The equivalent damping of the left resonator and the right resonator is always kept equal in size and opposite in sign through the control of the damping modulation circuits on the left and right sides, forming a PT symmetrical resonator system.

The left DC power source 12 is loaded on the upper and lower ends of the left resonant finger 1 to form a top-down DC current; the right DC power source 13 is loaded on the upper and lower ends of the right resonant finger 4 to form a bottom-up DC current. When there is a magnetic field perpendicular to the paper surface, both the left resonant finger 1 and the right resonant finger 4 are affected by the Lorentz force, and the Lorentz force changes the coupling coefficient between the left and right resonators, thereby changing the PT symmetrical resonance The resonant frequency of the system is modulated by the damping size to make the PT symmetrical resonator system work near the singular point, and the change of the resonant frequency of the PT symmetrical resonant system is detected to measure the magnitude of the magnetic field. Near the singular point of the PT symmetric resonator system, any perturbation will cause a great change in the resonance frequency, therefore, the MEMS resonant magnetic field sensor of the present invention has extremely high sensitivity.

The above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Anyone skilled in the art can easily think of changes or substitutions within the technical scope disclosed in the present invention. Should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (6)

A MEMS resonant magnetic field sensor based on the principle of PT symmetry is characterized in that: it includes a left resonator and a right resonator, and the left and right resonators are left-right mirror symmetrical structures, and are connected by coupling springs; wherein, The left resonator and the right resonator are respectively externally connected to a damping modulation circuit, and the damping modulation circuit controls the equivalent damping of the left resonator and the right resonator to be equal in size and opposite in sign, forming a PT symmetrical resonator system; It also includes a left DC power supply and a right DC power supply, the left DC power supply is loaded on the left resonator to form a top-down DC current, and the right DC power supply is loaded on the right resonator to form a bottom-up DC current Current, under the action of Lorentz force, the coupling coefficient between the left and right resonators changes, thereby changing the resonant frequency of the PT symmetrical resonant system, through the modulation of the damping size, the PT symmetrical resonator system works at the coupling coefficient and loss parameters equal singularity. A kind of MEMS resonant magnetic field sensor based on PT symmetry principle as claimed in claim 1, it is characterized in that said left resonator includes left resonant inserting finger, left drive inserting finger and left detection inserting finger, and right resonator includes right resonant inserting finger The insertion finger, the right drive insertion finger and the right detection insertion finger, the upper and lower ends of the left resonant insertion finger and the right resonance insertion finger are fixed on the sensor substrate, and the rest are suspended above the substrate; the left driving insertion finger, the left detection insertion finger The finger, the right driving finger and the right detecting finger are fixed on the sensor substrate, and the coupling spring is suspended above the sensor substrate. A MEMS resonant magnetic field sensor based on the principle of PT symmetry as claimed in claim 2, characterized in that a left drive port is set between the left drive finger and the left resonant finger, and between the left detection finger and the left resonant finger The left detection port is set; the right drive port is set between the right drive finger and the right resonance finger, and the right detection port is set between the right detection finger and the right resonance finger, and the left detection port, the left drive port and the right detection port and the right drive port are respectively connected to the damping modulation circuit. When there is a magnetic field perpendicular to the paper surface, the coupling coefficient between the left and right resonators is changed by the Lorentz force on the left resonant finger and the right resonant finger. A method for using a MEMS resonant magnetic field sensor based on the principle of PT symmetry, characterized in that it comprises the following steps: S1, respectively controlling the left resonator and the right resonator through the damping modulation circuit, so that the equivalent damping of the left resonator and the right resonator is always kept equal in size and opposite in sign, forming a PT symmetrical resonator system; S2, turning on the left DC power supply and the right DC power supply, so that the left resonant finger in the left resonator forms a top-down DC power supply, and the right resonant finger in the right resonator forms a bottom-up DC power supply; S3, when there is a magnetic field perpendicular to the paper surface, the left resonant finger and the right resonant finger are subjected to the Lorentz force, which changes the coupling coefficient between the left and right resonators and changes the resonant frequency of the PT symmetrical resonant system; S4, make the PT symmetrical resonator system work at the singular point where the coupling coefficient and the loss parameter are equal through damping size modulation, and detect the change of the resonant frequency of the PT symmetrical resonant system to measure the magnetic field. A resonator system based on the principle of PT symmetry is characterized in that it comprises: a left resonator, a right resonator and a damping modulation circuit; The left resonator and the right resonator have left and right mirror symmetrical structures, and are respectively connected to the damping modulation circuit; The damping modulation circuit at least includes an electromechanical conversion control circuit, a motor conversion control circuit, a gain control circuit and a phase control circuit. The electromechanical conversion control circuit converts the output of the left resonator and the right resonator into electrical signals, and passes the gain control circuit and The phase control circuit controls the gain and phase, and then converts it into a damping modulation control signal through the motor conversion control circuit, and feeds it back to the left resonator and the right resonator. Among them, the gain controller and the phase controller control the magnitude of the damping, and the phase controller Control the positive and negative of damping; The equivalent dampings of the left and right resonators in the described system are always equal in magnitude and opposite in sign. A resonator system based on the principle of PT symmetry as claimed in claim 5, wherein the phase controller controls the positive and negative of the damping, and when the damping modulation control signal is in phase with the resonator vibration signal, the system reflects negative damping; when When the damping modulation control signal is in antiphase with the resonator vibration signal, the system exhibits positive damping.

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