Three-order space-time symmetric wireless sensing system integrated with reader

Abstract

The invention, which relates to the technical field of wireless sensing, discloses a reader-integrated third-order space-time-symmetric wireless sensing system comprising a reader and a sensor which are in inductive coupling connection. The reader comprises a gain LC resonance unit and a relay LC resonance unit, and the gain LC resonance unit and the relay LC resonance unit are connected through a capacitance coupling assembly. The sensor is a loss LC resonance unit. According to the invention, the gain LC resonance unit and the relay LC resonance unit of the three-order PT symmetric system use capacitance coupling to replace the original inductance coupling mode. According to the coupling mode, the integration level of the reader can be further improved, and meanwhile the coupling coefficient of the reading end can be adjusted more conveniently and rapidly.

Description

Technical Field

[0001] This invention relates to the field of wireless sensing technology, and more particularly to a third-order parity-time symmetric wireless sensing system with an integrated reader. Background Technology

[0002] Passive wireless inductive-capacitive (LC) sensors are widely used in parameter monitoring in harsh environments, for implantable devices, and for long-distance readings due to their small size, long lifespan, and wire-free operation. A typical LC sensor consists of an inductor and a capacitor, achieving real-time measurement through near-field inductive coupling. When the measured parameter changes, causing a change in capacitance, the resonant frequency of the LC resonator shifts.

[0003] However, traditional LC sensors have a low quality factor (Q value), resulting in low system resolution. Furthermore, for a disturbance... Frequency shift and The relationship is often linear, that is... It is not very sensitive to small perturbations.

[0004] Parity-time (PT) symmetry is a physical concept proposed in quantum mechanics, referring to the symmetry of a system under space reversal and time reversal. Research shows that the frequency bifurcation characteristics of PT-symmetric systems can improve the sensitivity of LC wireless sensing systems. A PT-symmetric system has an exception point (EP), where the system's eigenspectral density undergoes degeneracy. At this point, the system is highly sensitive to small external perturbations. Very sensitive. For a For a PT-symmetric system, the eigenvalues ​​and perturbations follow a certain relationship. The relationship, when At that time, due to In other words, singularities can significantly improve the system's sensitivity to small disturbances, and the higher the order of the singularity, the greater the sensitivity improvement. This property can be used to construct highly sensitive wireless sensing systems based on PT-symmetric systems.

[0005] Existing third-order PT-symmetric wireless sensing systems typically consist of three LC resonators arranged in a gain-lossless repeater-loss configuration, with adjacent resonators coupled through mutual inductance. The gain and loss parameters of the system can be adjusted... and coupling coefficient Satisfying the singularity parameter conditions This allows for ultra-sensitive sensing. However, existing systems have stringent requirements for the coupling coefficient, necessitating strict control over the distance between resonators. Furthermore, mutual inductance between non-adjacent resonators is difficult to avoid, easily introducing unnecessary errors into the system. Summary of the Invention

[0006] The purpose of this invention is to provide a third-order parity-time symmetric wireless sensing system with an integrated reader. The reader is composed of a gain-side inductor and a repeater connected by capacitive coupling. When performing sensing applications, only the distance between the repeater inductor and the loss-side inductor needs to be adjusted, which makes it easier to adjust the system coupling coefficient and avoids interference caused by the mutual coupling between the gain-side inductor and the loss-side inductor.

[0007] To achieve the above objectives, the present invention provides the following technical solution: On one hand, the present invention provides a third-order parity-time symmetric wireless sensing system with an integrated reader, including a reader and a sensor connected by inductive coupling; the reader includes a gain LC resonant unit and a relay LC resonant unit, and the gain LC resonant unit and the relay LC resonant unit are connected by a capacitive coupling component; the sensor is a loss LC resonant unit.

[0008] The coupling method between the gain LC resonant unit and the relay LC resonant unit improves the system integration and makes it easier to adjust the coupling coefficient at the reading end.

[0009] In some embodiments, the gain LC resonant unit includes inductors connected in parallel. and capacitor and to the inductor and capacitor The parallel circuit provides the negative resistance for gain. The relay LC resonant unit includes inductors connected in parallel. and capacitor The capacitive coupling component is connected to the inductor. With the inductor Coupling capacitance between .

[0010] In some embodiments, the sensor includes inductors connected in parallel. ,capacitance and loss resistance The capacitor The capacitance value changes in response to changes in the external physical quantity being measured.

[0011] In some embodiments, the reader and the sensor are inductively coupled via a relay LC resonant unit and a loss LC resonant unit side.

[0012] In some embodiments, the coupling coefficient between the reader and the sensor for: ; The coupling coefficient between the gain LC resonant unit and the relay LC resonant unit for: ; In the formula, For inductance and inductor Mutual inductance between them; for The equivalent capacitance value.

[0013] In some embodiments, the coupling coefficient is changed by adjusting the relative distance between the reader and the sensor.

[0014] In some embodiments, by adjusting the coupling capacitor The capacitance value, the negative resistance Provided gain, the loss resistance The resistance value and the coupling coefficient enable the system to operate in a third-order singularity state.

[0015] In some embodiments, when the system operates in a third-order singular state, the following conditions must be met: ; ; ; ; ; ; In the formula, The gain loss coefficient of the gain LC resonant unit; The gain loss coefficient of the loss LC resonant unit; for , , The equivalent inductance value; for , The equivalent value; for , The equivalent value.

[0016] On the other hand, the present invention provides a third-order parity-time symmetric wireless sensing method with an integrated reader. Using the aforementioned system, the reader and sensor are arranged at a predetermined relative distance, causing the system to operate in a third-order singularity state. An excitation signal is applied to the reader, and the reflection spectrum response of the system is acquired. Based on the offset of characteristic frequencies in the reflection spectrum response, the capacitance in the sensor is determined. The change in capacitance is used to obtain information about the physical quantity being measured.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention operates at the singularity of a third-order PT-symmetric system. Due to its extreme sensitivity to small external perturbations, it can achieve highly sensitive wireless sensing.

[0018] This invention replaces the original inductive coupling method with capacitive coupling between the gain LC resonant unit and the relay LC resonant unit of a third-order PT-symmetric system. This coupling method can improve the integration of the reader and makes the coupling coefficient adjustment at the reading end more convenient. In addition, this invention avoids the mutual inductance between the gain-side inductor and the loss-side inductor, reducing system errors. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the change of intrinsic frequency with gain loss coefficient in Embodiment 1 of the present invention; wherein (a) is a schematic diagram of the change of the real part of intrinsic frequency with gain loss coefficient, and (b) is a schematic diagram of the change of the imaginary part of intrinsic frequency with gain loss coefficient. Figure 3 This is a schematic diagram of the change of the intrinsic frequency with disturbance when disturbed at a singular point in Embodiment 1 of the present invention; wherein (a) is a schematic diagram of the change of the real part of the intrinsic frequency with disturbance, and (b) is a schematic diagram of the change of the imaginary part of the intrinsic frequency with disturbance; Figure 4 This is a schematic diagram of the reflection spectrum under disturbance in Embodiment 1 of the present invention; Figure 5 This is a schematic diagram of the structure of the frequency source provided by the vector network analyzer in Embodiment 1 of the present invention. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0021] Example 1: Please see Figures 1-5 A third-order parity-time symmetric wireless sensing system with an integrated reader includes a reader and a sensor connected via inductive coupling.

[0022] The reader includes a gain LC resonant unit and a relay LC resonant unit, which are connected by a capacitive coupling component.

[0023] The gain LC resonant unit includes inductors connected in parallel. and capacitor and to the inductor and capacitor The parallel circuit provides the negative resistance for gain. .

[0024] The relay LC resonant unit includes inductors connected in parallel. and capacitor The capacitive coupling component is connected to the inductor. With the inductor Coupling capacitance between .

[0025] The gain LC resonant unit and the relay LC resonant unit are connected by a coupling capacitor. Coupled connection.

[0026] The coupling coefficient is: ; In the formula, for The equivalent capacitance value.

[0027] The sensor is a lossy LC resonant unit.

[0028] The sensor includes inductors connected in parallel. ,capacitance and loss resistance The capacitor As a sensitive capacitor, changes in the parameters of the external physical quantity being measured will cause the capacitance to... Changes occur, thus creating disturbances.

[0029] The reader and sensor are connected via the inductance of a relay LC resonant unit. With loss LC resonant unit inductor coupling.

[0030] The coupling coefficient between the reader and the sensor is: ; In the formula, Inductor and inductor The mutual inductance value between them.

[0031] In one specific embodiment, the present invention operates at singular points in a third-order PT-symmetric system through the following steps.

[0032] Applying Kirchhoff's laws Figure 1 In the circuit shown, the system component parameters are set as follows: ; ; ; ; Then there is, (1); In the formula, For inductance ,inductance ,inductance The equivalent inductance values, namely, the inductance values ​​of the gain LC resonant unit, the relay LC resonant unit, and the loss LC resonant unit; The resonant frequency; The imaginary unit; Angular frequency; The voltage of the gain LC resonant unit; The voltage of the relay LC resonant unit; The voltage of the loss LC resonant unit.

[0033] Let the system gain and loss coefficients be: The normalized frequency is: Rewrite formula (1) in matrix form: (2); in, ; ; In the formula, The resistors are for the gain LC resonant unit and the loss LC resonant unit; The gain loss coefficient of the gain LC resonant unit; This represents the gain loss coefficient of the lossy LC resonant unit.

[0034] Due to the coupling coefficient between system inductors It is very small, and the system works in nearby( The following approximation is made to formula (2): ; ; We can obtain: (3); In the formula, The gain loss coefficient of the gain LC resonant unit; The gain loss coefficient of the loss LC resonant unit; The characteristic equation is obtained through calculation: (4); To obtain the singularity, we need to make , ,get (5); The intrinsic frequencies were calculated as follows: (6); In the formula, The solution obtained by solving equation 5 is the normalized eigenfrequency of the system; The other two solutions obtained by solving equation 5 are the other two normalized eigenfrequency of the system; According to Equation 6, when At this point, a singularity can be obtained. The three eigenfrequencys of the system at this time are combined as follows: (7); In the formula, The three solutions obtained by solving Equation 5 at the singular points of the system are the three eigenfrequency of the system.

[0035] In a specific embodiment, the system disturbance analysis is illustrated by the following steps: Capacitance on the sensor side Apply perturbation ,make Therefore, Formula 3 can be rewritten as: (8); make And make the system at singular points, i.e. , ,and The eigenvalue equations are obtained as follows: (9); In the formula, This is the normalized frequency offset.

[0036] Using the perturbation method, Expand using the Newton-Puiseux series and take the first three terms, i.e. Substituting into the eigenvalue equation, we get: (10); Setting each term of Equation 10 to zero, we obtain: or or ; Therefore, the calculated eigenfrequency is: (11); In the formula, The disturbance applied to the system; For Newton-Puiseux series The coefficient; For Newton-Puiseux series The coefficient; For Newton-Puiseux series The coefficient; This represents the first normalized eigenfrequency offset after being perturbed at the singular point; This is the second normalized eigenfrequency offset after being perturbed at the singular point; This is the third normalized eigenfrequency offset after being perturbed at the singular point.

[0037] As can be seen, the intrinsic frequencies and the perturbation follow a certain relationship. The relationship.

[0038] like Figure 2 As shown, the system's eigenfrequency varies with the gain and loss coefficients. According to Equation 6, the eigenfrequency is given by... The system always has a real eigenfrequency. The three eigenfrequencys are at the singular point (at this time) ) merge. When At that time, the system has three real eigenfrequency; when At this time, the system has one real eigenfrequency and a pair of conjugate eigenfrequencys.

[0039] When the system is disturbed, its eigenfrequency is as shown in Equation 11. Let... , At this point, the system is at a singular point, and the capacitance of the sensor... When a perturbation is applied, the eigenfrequency changes with the perturbation. Changes such as Figure 3 As shown, the imaginary parts of the two eigenfrequency branches marked with an asterisk are smaller, indicating that these two eigenfrequency branches can be observed more clearly in actual tests. At the same time, it can be seen from (a) that the real parts corresponding to the eigenfrequency branches with smaller imaginary parts have larger frequency shifts, which makes the system have higher sensitivity.

[0040] To more clearly illustrate the effects of the present invention, the system component parameters are set as follows: , , ,at this time ,make ;make According to the singularity condition Therefore, let When a disturbance is applied to the system's capacitance, the system's reflection coefficient is read. .like Figure 4 As shown, when the system is disturbed, a clear frequency shift can be observed, and this frequency corresponds to... Figure 3 The intrinsic frequencies marked by the star symbol. Figure 3 The discrete points in (a) are obtained from simulations under different perturbations. The frequency corresponding to the minimum value is found to be in good agreement between the simulation results and the theoretical results.

[0041] like Figure 5 As shown, the system's frequency readout is achieved using a vector network analyzer (VNA), which can be represented as a negative resistor. ,Will With a resistor Parallel connection can produce negative resistance. They satisfy .

[0042] To make the system a singularity, let , , , ,in Determine the coupling coefficient. and After that, it can be based on Calculated and .

[0043] Capacitance on the sensor side The sensitive element can be selected; when the parameters of the external test object change, the capacitance will change. Changes occur, thus creating a disturbance. Frequency readout using a VNA allows for sensing applications of capacitance-sensitive parameters.

[0044] Example 2 A third-order parity-time symmetric wireless sensing method integrating a reader is disclosed. Utilizing the aforementioned system, the reader and sensor are arranged at a predetermined relative distance, enabling the system to operate in a third-order singularity state. An excitation signal is applied to the reader, and the reflection spectrum response of the system is acquired. Based on the offset of characteristic frequencies in the reflection spectrum response, the capacitance in the sensor is determined. The change in capacitance is used to obtain information about the physical quantity being measured.

[0045] This invention constructs a more compact integrated reader by capacitively coupling the gain LC resonant unit and the relay LC resonant unit. This avoids coupling between non-adjacent resonators, and only requires adjusting the coupling distance between the sensor and the reader, making the adjustment of the system coupling coefficient more convenient and simplifying the system configuration and calibration process.

Claims

1. A third-order parity-time symmetric wireless sensing system with an integrated reader, characterized in that, It includes a reader and a sensor connected by inductive coupling; the reader includes a gain LC resonant unit and a relay LC resonant unit, which are connected by a capacitive coupling component; the sensor is a loss LC resonant unit.

2. The third-order parity-time symmetric wireless sensing system with an integrated reader according to claim 1, characterized in that, The gain LC resonant unit includes inductors connected in parallel. and capacitor and to the inductor and capacitor The parallel circuit provides the negative resistance for gain. The relay LC resonant unit includes inductors connected in parallel. and capacitor The capacitive coupling component is connected to the inductor. With the inductor Coupling capacitance between .

3. A third-order parity-time symmetric wireless sensing system with an integrated reader according to claim 2, characterized in that, The sensor includes inductors connected in parallel. ,capacitance and loss resistance .

4. A third-order parity-time symmetric wireless sensing system with an integrated reader according to claim 3, characterized in that, The reader and the sensor are inductively coupled through a relay LC resonant unit and a loss LC resonant unit.

5. A third-order parity-time symmetric wireless sensing system with an integrated reader according to claim 4, characterized in that, The coupling coefficient between the reader and the sensor for: ; The coupling coefficient between the gain LC resonant unit and the relay LC resonant unit for: ; In the formula, For inductance and inductor Mutual inductance between them; for The equivalent capacitance value.

6. A third-order parity-time symmetric wireless sensing system with an integrated reader according to claim 5, characterized in that, The coupling coefficient is changed by adjusting the relative distance between the reader and the sensor.

7. A third-order parity-time symmetric wireless sensing system with an integrated reader according to claim 5, characterized in that, By adjusting the coupling capacitor The capacitance value, the negative resistance Provided gain, the loss resistance The resistance value and the coupling coefficient enable the system to operate in a third-order singularity state.

8. A third-order parity-time symmetric wireless sensing system with an integrated reader according to claim 6, characterized in that, When the system operates in a third-order singular state, the following conditions must be met: ； ; ; ; ; In the formula, The gain loss coefficient of the gain LC resonant unit; The gain loss coefficient of the loss LC resonant unit; For inductance ,inductance ,inductance The equivalent inductance value; for , The equivalent value; for , The equivalent value.

9. A third-order parity-time symmetric wireless sensing method with an integrated reader, utilizing the system described in any one of claims 1-8, characterized in that, The reader and sensor are arranged at a predetermined relative distance, enabling the system to operate in a third-order singularity state; an excitation signal is applied to the reader, and the reflection spectrum response of the system is acquired; based on the offset of characteristic frequencies in the reflection spectrum response, the capacitance in the sensor is determined. The change in capacitance is used to obtain information about the physical quantity being measured.

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