A high-sensitivity sensing circuit, sensing method and pressure sensor based on transmission valley degeneracy

Abstract

The application belongs to a high-sensitivity sensing circuit based on transmission valley degeneracy, a sensing method and a pressure sensor, and the sensing circuit comprises: a first LC resonator and a second LC resonator, the first LC resonator and the second LC resonator are weakly coupled with a transmission line with a predetermined characteristic impedance; a coupling element connected between the first LC resonator and the second LC resonator for realizing the coupling between the two resonators; and a signal extraction device for extracting the scattering parameter of the transmission line; wherein the first LC resonator and the second LC resonator are used to make the sensing circuit work at the transmission valley degeneracy point by adjusting the coupling element and the external coupling element, and when the coupling element is disturbed, the splitting of the spectral line valley in the reflection spectrum occurs. The application significantly improves the output signal-to-noise ratio and solves the contradiction between sensitivity and noise.

Description

Technical Field

[0001] This invention relates to the field of pressure sensor technology, and in particular to a high-sensitivity sensing circuit, sensing method and pressure sensor based on transmission valley degeneracy. Background Technology

[0002] Anomalies (EPs), as degenerate points in non-Hermitian systems, possess unique eigenvalue and eigenvector merging properties that enable them to exhibit extremely strong responses to small perturbations, providing a theoretical basis for the design of high-sensitivity sensors. Traditional schemes for constructing anomalies are mostly based on the concept of parity-time symmetry, requiring two coupled resonators to have separate gains and losses, with the gain and loss being strictly equal. However, despite the potential for sensitivity in anomaly-based sensors, the noise amplification problem near the anomaly due to incomplete eigenvalues ​​prevents a significant improvement in their actual signal-to-noise ratio performance.

[0003] Pressure sensors are devices that convert pressure signals into electrical signals and are widely used in industrial control, automotive electronics, and medical equipment. Their technical approaches are diverse, among which capacitive pressure sensors have become an important branch due to their high sensitivity, low power consumption, and excellent dynamic response characteristics. This type of sensor achieves measurement by detecting changes in capacitance caused by deformation of plates or changes in the distance between them due to pressure. Existing pressure sensors, especially in measuring minute pressures or high-precision scenarios, generally face the core challenges of low signal-to-noise ratio and insufficient sensitivity. A low signal-to-noise ratio easily leads to the output signal being overwhelmed by interference, while limited sensitivity restricts its effective detection of subtle pressure changes. These shortcomings collectively limit the measurement accuracy and reliability of sensors under complex operating conditions, constituting a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0004] The purpose of this invention is to provide a high-sensitivity sensing circuit, sensing method, and pressure sensor based on transmission valley degeneracy, thereby resolving the contradiction between sensitivity and noise.

[0005] To achieve the above objectives, the present invention provides the following solution: This invention provides a high-sensitivity sensing circuit based on transmission valley degeneracy, comprising: The first LC resonator and the second LC resonator are weakly coupled to a transmission line having a predetermined characteristic impedance, respectively. A coupling element is connected between the first LC resonator and the second LC resonator to achieve coupling between the two resonators; And a signal extraction device for extracting the scattering parameters of the transmission line; Specifically, by utilizing the first LC resonator and the second LC resonator, and by adjusting the coupling element and the external coupling element, the sensing circuit is made to operate at the transmission valley degeneracy point, and when the coupling element is subjected to a slight perturbation, the spectral valleys in the reflection spectrum split.

[0006] Optionally, the coupling element includes a perturbation capacitor, which is used to change the capacitance value to introduce a perturbation ε.

[0007] The present invention also provides a high-sensitivity sensing method based on transmission valley degeneracy, for implementation according to a high-sensitivity sensing circuit based on transmission valley degeneracy, comprising: By adjusting the sensor circuit to operate at the transmission valley degeneracy point, applying a perturbation to the coupling element, and using a signal extraction device to measure the frequency splitting in the reflection spectrum; The sensitivity of the frequency split to the perturbation is proportional to the reciprocal of the square root of the perturbation, thus making the sensitivity under the perturbation tend to infinity.

[0008] Optionally, measuring the frequency splitting in the reflection spectrum using a signal extraction device includes: Using the time-domain coupled-mode theory analysis model, the complex amplitude of the LC resonator mode in the sensing circuit is obtained. Based on the complex amplitude, the complex forms of the voltage and current of the first and second LC resonators are obtained, and substituted into the Kirchhoff equations of the circuit without transmission lines, the formula characterized by Hamiltonian is obtained. When the isolated LC resonator is coupled to the transmission line through a coupling element, the voltage of the transmission line is the superposition of forward and reverse propagating waves, and is expressed in the form of complex amplitude. Based on Kirchhoff's equations for the voltage and current at the connection between the transmission line and the resonator, and the transmission line voltage expressed in complex amplitude form, the Kirchhoff equations are restated and combined with the formula characterized by Hamiltonian to obtain the modal dynamics evolution equations. The reflection coefficient is obtained based on the modal dynamics evolution equation. The reflection coefficient is analyzed to obtain the frequency splitting in the reflection spectrum.

[0009] Optionally, the reflection coefficient r is: ; in, Let reflectivity be the reflectivity of the two transmission line ports. For input frequency, External coupling rate, The coupling ratio between the two resonators. It is the imaginary unit.

[0010] Optionally, analyzing the reflection coefficient includes: exist Under certain conditions, the reflection coefficient has a double zero, that is, the zero point of the reflection spectrum is at... The point of convergence, which is a valley value in the spectrum with a depth that can reach 0, is called the transmission valley degeneracy point; when There are two real zeros, which are two valleys in the spectrum that can reach 0, and the frequency split in the reflection spectrum is obtained. when The two zeros are conjugate to each other, and the value is a valley on the spectrum but cannot reach 0.

[0011] The present invention also provides a high-sensitivity pressure sensor based on transmission valley degeneracy, including the aforementioned high-sensitivity sensing circuit based on transmission valley degeneracy, wherein the coupling element includes a capacitive pressure sensing head and a fine-tuning capacitor connected in parallel, and an LC resonator is connected to a signal reading device through a transmission line to obtain the scattering parameters at the two ports of the resonant frequency, so that the sensor operates at the transmission valley degeneracy point, and a micro-perturbation is applied to the coupling strength to cause the splitting of the spectral valley, thereby achieving high-sensitivity detection of small pressures.

[0012] Optionally, applying a perturbation to the coupling strength to split spectral valleys can achieve highly sensitive detection of minute pressures, including: A perturbation is applied to the coupling strength, causing the zero point of the transmission spectrum to split, which in turn causes the position of the transmission valley frequency to shift. The valley frequency of the spectral line is extracted by Lorentz bimodal fitting to calculate the frequency split, and the magnitude of the environmental pressure is inferred from the frequency split.

[0013] The beneficial effects of this invention are as follows: 1. A novel physical mechanism based on transmission valley degeneracy is proposed and defined, namely, the degeneracy of the zeros of the transfer function (rather than the system eigenvalues). Under this condition, the system exhibits a square root response similar to that of a second-order outlier, but does not need to satisfy a strict non-Hermitian gain-loss balance, providing a more stable and easily implemented path for high-sensitivity sensing.

[0014] 2. Electrically, a tunable coupled LC resonant circuit is used. By adjusting the matching between the coupling capacitor and the external coupling capacitor, the circuit is initially operated near the degeneracy point of the transmission valley, and spectral splitting of the transmission valley in the reflection spectrum is observed. It has the potential to be applied to other physical platforms and even realize multi-physics field sensing integration.

[0015] 3. By replacing the coupling capacitor with a pressure-sensitive capacitor or other sensitive capacitor, a high-sensitivity pressure sensor can be constructed, which significantly reduces system complexity, power consumption, and cost. Furthermore, while achieving a square root-level increase in sensitivity, it maintains low system noise, thereby significantly improving the output signal-to-noise ratio and resolving the trade-off between sensitivity and noise.

[0016] In summary, compared to existing schemes that utilize parity-time symmetry to construct anomalies for high-sensitivity sensors, this invention's transmission valley degeneracy scheme eliminates the need for negative resistance and, consequently, an additional DC voltage source. This reduces power consumption and operational complexity, facilitating on-chip integration and large-scale manufacturing, thus providing a feasible solution for the miniaturization and practical application of high-sensitivity sensors. Furthermore, the transmission valley degeneracy scheme achieves the same sensitivity level as schemes utilizing parity-time symmetry to construct anomalies, but with a higher signal-to-noise ratio. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of a high-sensitivity sensing circuit based on transmission valley degeneracy according to an embodiment of the present invention; Figure 2 The graph shows the relationship between pressure and frequency offset measured in the experiment according to an embodiment of the present invention. (a) is the result of fitting with the square root, and (b) is the result of fitting in log-log coordinates with a slope of 0.496, which is very close to 0.5. The error bars represent the standard deviation of the three measurements. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] Technical terminology definition: An exceptional point (EP) is a special degeneracy point in the parameter space of a non-Hermitian Hamiltonian, where not only are the eigenvalues ​​of the system degenerate, but the corresponding eigenstates are also degenerate. This is fundamentally different from the degeneracy points of Hermitian systems and is a phenomenon unique to non-Hermitian systems, usually accompanied by the spontaneous breaking of system symmetries (such as parity-time symmetry).

[0022] Transmission dip degeneracy (TDD): A physical mechanism that produces anomalous sensing responses by degenerating the zeros of the transfer function (rather than the system eigenvalues).

[0023] This embodiment proposes a high-sensitivity sensing circuit based on transmission valley degeneracy, including: The first LC resonator and the second LC resonator are weakly coupled to a transmission line having a predetermined characteristic impedance, respectively. A coupling element is connected between the first LC resonator and the second LC resonator to achieve coupling between the two resonators; And a signal extraction device for extracting the scattering parameters of the transmission line; Specifically, by utilizing the first LC resonator and the second LC resonator, and by adjusting the coupling element and the external coupling element, the sensing circuit is made to operate at the transmission valley degeneracy point, and when the coupling element is subjected to a slight perturbation, the spectral valleys in the reflection spectrum split.

[0024] Furthermore, the coupling element includes a perturbation capacitor, which is used to change the capacitance value to introduce a perturbation ε.

[0025] Specifically, the core of this circuit lies in the use of a passive, reciprocal circuit structure, including a sensitive capacitor and a coupled LC resonant detection circuit, whose output is read by a network analyzer to obtain scattering parameters.

[0026] like Figure 1 As shown, the circuit contains two LC resonant circuits, consisting only of a capacitor and an inductor connected in series. The equivalent capacitance of the first LC resonator is C1, and the equivalent inductance is L1; the equivalent capacitance of the second LC resonator is C2, and the equivalent inductance is L2. To satisfy the transmission spectrum degeneracy condition, C1=C2=C and L1=L2=L must be satisfied. The first and second LC resonators are coupled through a coupling capacitor Cc, and a perturbation capacitor Cε is applied on top of this. The two LC resonators are weakly coupled to a transmission line with a characteristic impedance of Z0=50Ω through a capacitor Ce. The scattering parameters of the circuit are extracted using a network analyzer.

[0027] The detection limit using the commercially available NTY21002 as a perturbation capacitance sensor reaches 0.2 kPa, with an operating frequency in the kHz-MHz range. Sensor performance improves further when the sensitive capacitor exhibits better high-frequency characteristics. Furthermore, the detection range can reach up to approximately 20 kPa. Since the detection circuit consists only of basic LC components, its temperature characteristics and lifespan depend entirely on the performance of the sensitive capacitor. The sensor's sensitivity reaches up to 3 kHz / kPa in the low-pressure range and maintains high resolution even in the high-pressure range.

[0028] This embodiment also provides a high-sensitivity sensing method based on transmission valley degeneracy, which is implemented according to a high-sensitivity sensing circuit based on transmission valley degeneracy, including: By adjusting the sensor circuit to operate at the transmission valley degeneracy point, applying a perturbation to the coupling element, and using a signal extraction device to measure the frequency splitting in the reflection spectrum; The sensitivity of the frequency split to perturbations is proportional to the reciprocal of the square root of the perturbation, thus making the sensitivity under small perturbations tend to infinity.

[0029] Furthermore, measuring the frequency splitting in the reflection spectrum using a signal extraction device includes: Using the time-domain coupled-mode theory analysis model, the complex amplitude of the LC resonator mode in the sensing circuit is obtained. Based on the complex amplitude, the complex forms of the voltage and current of the first and second LC resonators are obtained, and substituted into the Kirchhoff equations of the circuit without transmission lines, the formula characterized by Hamiltonian is obtained. When the isolated LC resonator is coupled to the transmission line through a coupling element, the voltage of the transmission line is the superposition of forward and reverse propagating waves, and is expressed in the form of complex amplitude. Based on Kirchhoff's equations for the voltage and current at the connection between the transmission line and the resonator, and the transmission line voltage expressed in complex amplitude form, the Kirchhoff equations are restated and combined with the formula characterized by Hamiltonian to obtain the modal dynamics evolution equations. The reflection coefficient is obtained based on the modal dynamics evolution equation. The reflection coefficient is analyzed to obtain the frequency splitting in the reflection spectrum.

[0030] Specifically, we first calculate the conditions for transmission spectrum degeneracy without considering perturbation capacitance. Then, we analyze the high-sensitivity sensing circuit using coupled-mode theory: First, define the complex amplitude of the modes of the two LC resonators. , as follows: in Let be the capacitance value in the resonator, i be the imaginary unit, and L be the inductance value in the LC resonator. , Their conjugates are normalized so that This indicates that under weak coupling conditions ( The energy stored in the LC resonators on both sides of the lower plate. Voltage , and current , The definition is as follows: Will , , Substituting the complex form of the equation into Kirchhoff's equations for a circuit without a transmission line, and neglecting the rotational wave approximation... Terms, and considering the weak coupling approximation ( ), we can get: By definition The above equation can be written using a Hamiltonian. The form of representation: , When an isolated LC resonator system is connected to an external transmission line (characteristic impedance) = 50Ω) through capacitor During coupling, for a transmission line, the voltage V TL With current I TL It manifests as the superposition of forward and reverse propagating waves ( To define the scattering parameters, the transmission line voltage is expressed as a complex amplitude as follows: ,in ; Kirchhoff's equations describing the voltage and current at the connection between the transmission line and the resonator can be written as: ; Assuming weak coupling And similarly, using the rotating wave approximation and utilizing... Normalization allows us to reformulate the above Kirchhoff equations into the following form: ; in Combining this equation with the system formula expressed in terms of Hamiltonian, we can obtain... Replace with The TDD model can be described using the classic temporal coupled-mode theory (TCMT). Specifically, it involves the interaction between external inputs and the TDD model. During coupling, the mode amplitude of the resonator and output The dynamic evolution equation is as follows: ; Using the scattering matrix S (S) 11 This represents the reflectivity, which has one port input and one port output. 12 S represents the transmittance, which is the input at port 1 and the output at port 2. 21 S represents the transmittance of a 2-port input, 1-port output port. 22 The input is defined as the reflectivity of a 2-port input and a 2-port output. and output The relationship between ( The reflection coefficient can be obtained. : in, Let reflectivity be the reflectivity of the two transmission line ports. For input frequency, External coupling rate, The coupling ratio between the two resonators. It is the imaginary unit.

[0031] exist Under certain conditions, the reflection coefficient has a double zero, that is, the zero point of the reflection spectrum is at... At this point, coupling occurs, which is represented in the spectrum as a valley with a depth reaching 0. The condition for this critical coupling is the Transmission Valley Degeneracy Point (TDD), which is also represented in the spectrum as a valley with a depth reaching 0. When There exist two zeros of real numbers, which are represented on the spectrum as two valleys with a depth reaching 0; when The two zeros are conjugate to each other, which is reflected in the spectrum as a valley value but cannot reach 0.

[0032] Next, consider the coupling capacitor C. c The perturbation when adding a perturbation, let the perturbation be... And let the system initially operate under the transmission valley degeneracy condition (i.e., adjust the parameters so that...) Similarly, the zero-point changes when a perturbation is applied can be obtained: when The zero-point frequency splitting relationship is approximately as follows: This square root relationship is similar to the response characteristics of a sensing scheme based on second-order anomalies. Therefore, the zero-point frequency splitting caused by adding perturbations, i.e., the frequency splitting amount... perturbation Sensitivity The reciprocal of the square root of the perturbation Proportional, thus leading to when As the capacitance approaches zero, the sensitivity approaches infinity, highlighting its potential for high sensitivity under small perturbations. Replacing the perturbation capacitor with a sensitive capacitor of varying area / distance allows for the fabrication of highly sensitive capacitive sensors, such as capacitive pressure sensors or capacitive accelerometers.

[0033] This embodiment proposes a transmission valley degeneracy (TDD) sensing method, a novel sensing mechanism independent of outliers. Its core lies in achieving degeneracy at the zero point of the transmission function. Near this degeneracy point, an introduced perturbation causes the valleys in the transmission spectrum to split and shift, with the degree of splitting proportional to the square root of the perturbation intensity, exhibiting response characteristics similar to second-order outliers. Unlike parity-time symmetric schemes that require precise control of gain and loss to achieve outliers, transmission valley degeneracy can be implemented in a purely lossy system, significantly reducing experimental complexity. The effectiveness of the transmission valley degeneracy mechanism and its potential to improve the signal-to-noise ratio of sensors can be verified on multiple experimental platforms.

[0034] This embodiment provides a practical sensing method based on the transmission valley degeneracy mechanism. A Hamiltonian and transfer function satisfying the transmission valley degeneracy condition are constructed using a simple LC detection circuit and a pressure-sensitive capacitor. This allows the frequency splitting of the valley values ​​in S11 / S22 to be extracted using a network analyzer when the structure operates near the transmission valley degeneracy point. This frequency splitting relationship is square-law related to the applied pressure, ensuring high sensitivity even under low pressure. Furthermore, the completeness of the intrinsic basis demonstrates the improved signal-to-noise ratio.

[0035] Compared to existing schemes that utilize parity-time symmetry to construct outliers for high-sensitivity sensors, this scheme using transmission valley degeneracy eliminates the need for negative resistance and an additional DC voltage source. This reduces power consumption and operational complexity, making it easier to integrate on-chip and mass-produce, thus providing a feasible solution for the miniaturization and practical application of high-sensitivity sensors. Furthermore, this transmission valley degeneracy scheme achieves the same sensitivity level as schemes using parity-time symmetry to construct outliers, but with a higher signal-to-noise ratio.

[0036] This method allows for the gradual observation of a shift in the frequency split Δf during pressurization. The shift Δf - Δf0 can be extracted using bimodal Lorentz fitting. Based on this, the relationship between pressure and frequency shift can be plotted as follows: Figure 2 The results (a)-(b) show a radical relationship, which is consistent with the theoretical results.

[0037] This embodiment also provides a high-sensitivity pressure sensor based on transmission valley degeneracy, such as a high-sensitivity sensing circuit based on transmission valley degeneracy, wherein the coupling element includes a capacitive pressure sensing head and a fine-tuning capacitor connected in parallel, and the LC resonator is connected to the signal reading device through a transmission line to obtain the scattering parameters at the two ports of the resonant frequency, so that the sensor works at the transmission valley degeneracy point, and the spectral valley splitting is caused by applying a micro-perturbation to the coupling strength, thereby realizing high-sensitivity detection of small pressure.

[0038] Furthermore, applying a perturbation to the coupling strength to split spectral valleys enables highly sensitive detection of minute pressures, including: A perturbation is applied to the coupling strength, causing the degeneracy zeros of the perturbation transmission spectrum to split, which in turn causes the transmission valley frequency position to shift. The valley frequency of the spectral line is extracted by Lorentz bimodal fitting to calculate the frequency split, and the magnitude of the environmental pressure is inferred from the frequency split.

[0039] Specifically, the working process of a pressure sensor constructed based on the principle of transmission valley degeneracy: A capacitive pressure sensor (using the commercially available NTY21002 as an example) is connected in parallel with a trimmer capacitor to replace the coupling capacitor between the two resonators. The entire system is placed in an atmospheric environment. The two resonators are connected to a signal reading device, such as a network analyzer, via transmission lines. The network analyzer sweeps the frequency to obtain the resonant frequency. Regarding the scattering parameters of the two nearby ports, this embodiment only observes the reflectivity of the two ports measured by a network analyzer. or If the splitting of the spectral valleys is not observed, the fine-tuning capacitor is increased to initially reveal two distinct valley values ​​in the transmission spectrum, thus aligning the system near the transmission valley degeneracy point (TDD). This condition is defined as the sensor's initial condition. S11 or S22 at this point is extracted, and the valley values ​​of the spectral lines are extracted using Lorentz bimodal fitting to calculate the frequency splitting at this point. 0.

[0040] The sensor is placed in a variable pressure environment, and micro-perturbation pressure is applied. P reduces the spacing between the sensitive capacitors to increase the perturbation capacitance value, thereby applying a perturbation to the coupling strength. This will cause the zero point of the perturbation transmission spectrum to continue shifting, which is reflected in the shift of the two transmission valley frequency positions in the S22 spectrum measured by the network analyzer. The valley values ​​of the spectral lines are still extracted by Lorentz bimodal fitting to calculate the frequency split at this time. At this point, according to the above principles, we have: Based on the pressure-capacitance relationship graph of this commercial sensor head, which shows a linear relationship around low pressure (kPa), the square root relationship between frequency splitting and pressure can be experimentally measured. Specific experimental results are as follows... Figure 2 As shown in (a)-(b), this is a nonlinear sensor. In practical applications, the magnitude of the ambient pressure can be deduced from the measured frequency split. Specifically, the sensitivity is defined as d. ) / d The closer P is to the initial conditions, the higher the sensitivity, making it suitable for highly sensitive detection of minute pressures. In some implementations, the coupling between the two resonators is not limited to capacitive coupling and can be replaced with inductive coupling to achieve wireless telemetry or other coupling methods.

[0041] By replacing the pressure-sensitive capacitor with other sensitive MEMS capacitors, high-sensitivity accelerometers, gyroscopes, or temperature and humidity detection functions can be constructed.

[0042] Frequency splitting can be introduced by other types of perturbations, such as perturbations caused by coupling between inductors or perturbations caused by capacitors and inductors on both sides.

[0043] Removing the capacitor Ce and directly coupling the LC resonant system to the transmission line can also achieve transmission valley degeneracy.

[0044] It is worth noting that, due to the non-negligible parasitic parameters of the system at high frequencies, unavoidable component errors, and the presence of noise, the valley of the transmission spectrum will not reach 0. Therefore, when selecting parameters, capacitors and inductors with high self-resonant frequencies, high quality factors, and low manufacturing errors should be chosen to meet the condition of operating near the transmission valley degeneracy point as much as possible.

[0045] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A high-sensitivity sensing circuit based on transmission valley degeneracy, characterized in that, include: The first LC resonator and the second LC resonator are weakly coupled to a transmission line having a predetermined characteristic impedance, respectively. A coupling element is connected between the first LC resonator and the second LC resonator to achieve coupling between the two resonators; And a signal extraction device for extracting the scattering parameters of the transmission line; Specifically, by utilizing the first LC resonator and the second LC resonator, and by adjusting the coupling element and the external coupling element, the sensing circuit is made to operate at the transmission valley degeneracy point, and when the coupling element is subjected to a slight perturbation, the spectral valleys in the reflection spectrum split.

2. The high-sensitivity sensing circuit based on transmission valley degeneracy according to claim 1, characterized in that, The coupling element includes a perturbation capacitor, which is used to change the capacitance value to introduce a perturbation ε.

3. A high-sensitivity sensing method based on transmission valley degeneracy, used to implement the high-sensitivity sensing circuit based on transmission valley degeneracy according to any one of claims 1-2, characterized in that, include: By adjusting the sensor circuit to operate at the transmission valley degeneracy point, applying a perturbation to the coupling element, and using a signal extraction device to measure the frequency splitting in the reflection spectrum; The sensitivity of the frequency split to the perturbation is proportional to the reciprocal of the square root of the perturbation, thus making the sensitivity under the perturbation tend to infinity.

4. The high-sensitivity sensing method based on transmission valley degeneracy according to claim 3, characterized in that, Measuring frequency splitting in the reflection spectrum using a signal extraction device includes: Using the time-domain coupled-mode theory analysis model, the complex amplitude of the LC resonator mode in the sensing circuit is obtained. Based on the complex amplitude, the complex forms of the voltage and current of the first and second LC resonators are obtained, and substituted into the Kirchhoff equations of the circuit without transmission lines, the formula characterized by Hamiltonian is obtained. When the isolated LC resonator is coupled to the transmission line through a coupling element, the voltage of the transmission line is the superposition of forward and reverse propagating waves, and is expressed in the form of complex amplitude. Based on Kirchhoff's equations for the voltage and current at the connection between the transmission line and the resonator, and the transmission line voltage expressed in complex amplitude form, the Kirchhoff equations are restated and combined with the formula characterized by Hamiltonian to obtain the modal dynamics evolution equations. The reflection coefficient is obtained based on the modal dynamics evolution equation. The reflection coefficient is analyzed to obtain the frequency splitting in the reflection spectrum.

5. The high-sensitivity sensing method based on transmission valley degeneracy according to claim 4, characterized in that, The reflection coefficient r is: ； in, Let reflectivity be the reflectivity of the two transmission line ports. For input frequency, External coupling rate, The coupling ratio between the two resonators. It is the imaginary unit.

6. The high-sensitivity sensing method based on transmission valley degeneracy according to claim 5, characterized in that, The analysis of the reflection coefficient includes: exist Under certain conditions, the reflection coefficient has a double zero, that is, the zero point of the reflection spectrum is at... The point of convergence, which is a valley value in the spectrum with a depth that can reach 0, is called the transmission valley degeneracy point; when There are two real zeros, which are two valleys in the spectrum that can reach 0, and the frequency split in the reflection spectrum is obtained. when The two zeros are conjugate to each other, and the value is a valley on the spectrum but cannot reach 0.

7. A high-sensitivity pressure sensor based on transmission valley degeneracy, characterized in that, The high-sensitivity sensing circuit based on transmission valley degeneracy as described in any one of claims 1-2 includes a coupling element comprising a capacitive pressure sensing head and a fine-tuning capacitor connected in parallel, and an LC resonator connected to a signal reading device via a transmission line to obtain scattering parameters at the two ports of the resonant frequency, so that the sensor operates at the transmission valley degeneracy point, and a micro-perturbation is applied to the coupling strength to cause the splitting of the spectral valley, thereby achieving high-sensitivity detection of small pressures.

8. The high-sensitivity pressure sensor based on transmission valley degeneracy according to claim 7, characterized in that, Applying a perturbation to the coupling strength to split spectral valleys enables highly sensitive detection of minute pressures, including: A perturbation is applied to the coupling strength, causing the zero point of the transmission spectrum to split, which in turn causes the position of the transmission valley frequency to shift. The valley frequency of the spectral line is extracted by Lorentz bimodal fitting to calculate the frequency split, and the magnitude of the environmental pressure is inferred from the frequency split.

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