A wireless sensor circuit based on non-Hermitian critical point and its manufacturing method

Abstract

The present invention provides a wireless sensor circuit based on non-Hermitian critical point, the circuit includes a sensing circuit and a reading circuit, and is characterized in that the sensing circuit includes: a planar inductor coil L s , Capacitive sensor C s , the capacitive sensor C s With the planar inductor L s in series, the capacitive sensor C s Adopting the interdigital electrode structure; the reading circuit includes a planar inductor coil L r , capacitor element C r , coaxial connector, network vector analyzer, the planar inductor coil L r and the capacitance element C r The network vector analyzer is connected in series with a planar inductor coil L through a coaxial connector. r and the capacitance element C r The wireless sensor circuit has a non-Hermitian critical point for the mutual inductance coupling coefficient #imgabs0# and the position of the reading circuit relative to the sensing circuit is to read the side capacitance C r , reading side inductance L r , and the sensing side capacitance C s , sensing side inductance L s And the internal resistance R of the network vector analyzer on the reading side r , the sensor resistance R s Substituting into the equation: #imgabs1# is determined by the mutual inductance coupling coefficient κ as the critical point #imgabs2#. The wireless sensor circuit design based on non-Hermitian critical points provided by the present invention offers relatively high flexibility, quality factor, and sensing sensitivity, enabling real-time signal monitoring and improving signal reading accuracy.

Description

Technical Field

[0001] The present invention relates to the field of wireless sensors, and in particular to a wireless sensor circuit based on a non-Hermitian critical point and a manufacturing method thereof. Background Art

[0002] Wireless sensors based on inductor-capacitor (LC) resonance are a type of electronic sensor device that can simultaneously transmit energy and data through inductive coupling without the need for wire connections. Due to their compact structure and lack of power supply, they are of great significance and have broad application scenarios in many advanced and emerging technology fields, including implantable biomedical sensors, industrial sensing equipment deployed in harsh or encapsulated environments, and wireless interconnected sensor networks for the Internet of Things.

[0003] Wireless sensors based on inductor-capacitor (LC) resonance mainly consist of a reading part and a sensing part. The capacitor in the LC resonant circuit of the sensing part is usually designed as a sensing element to detect changes in the external measured value (such as a physical or chemical quantity). Through this sensing element, the change in the signal to be measured is converted into a change in the capacitance in the sensing circuit, which in turn causes the system resonant frequency to shift, thereby realizing the detection of the signal to be measured.

[0004] Existing design solutions include traditional design architectures and parity-time symmetric design architectures. In the traditional design architecture, the reading part consists of a network vector analyzer and an inductor. The inherent loss characteristics of this traditional design architecture lead to a relatively low quality factor. As the resistance on the sensing side increases, the quality factor will be further reduced, and the sensitivity will be relatively limited, making it difficult to accurately monitor small signals. The reading part of the design architecture based on parity-time symmetry consists of a network vector analyzer, a resistor, an adjustable capacitor, and an inductor. During use, the reading side capacitor (C r ), resistance (R r ) and inductance (L r ) and the sensing side capacitance (C s ), resistance (R s ) and inductance (L s ) are strictly equal, that is, the gain parameter (g) and the loss parameter (γ) are equal g = γ, where While this architecture improves the signal quality factor and sensor sensitivity near singularity points, it presents several challenges. First, stringent parameter matching limits sensor design flexibility. Second, during sensor testing, additional time is required to precisely adjust the adjustable capacitance of the reading portion, either manually or through complex electrical modules, to ensure that the capacitance always equals the capacitance of the sensing portion. This makes real-time signal monitoring difficult. Furthermore, because the system's characteristic frequency is sensitive to all electrical parameters, the adjustment process can result in inaccurate final signal readings. Summary of the Invention

[0005] The present invention solves the problems of relatively low quality factor and sensing sensitivity, harsh design conditions, difficulty in achieving real-time signal monitoring, and inaccurate signal reading in existing wireless sensors based on inductor-capacitor resonance. It provides a wireless sensor circuit based on non-Hermitian critical points and a manufacturing method to solve the above problems.

[0006] The technical solutions of the present invention are as follows:

[0007] The present invention provides a wireless sensor circuit based on non-Hermitian critical point, the circuit includes a sensing circuit and a reading circuit, and is characterized in that the sensing circuit includes: a planar inductor coil L s , Capacitive sensor C s , the capacitive sensor C s With the planar inductor L s in series, the capacitive sensor C s The interdigital electrode structure is adopted; the reading circuit includes a planar inductor coil L r , capacitor element C r , coaxial connector, network vector analyzer, the planar inductor coil L r and the capacitance element C r The network vector analyzer is connected in series with a planar inductor coil L through a coaxial connector. r and the capacitance element C r The non-Hermitian critical point of the wireless sensor circuit is the mutual inductance coupling coefficient The position of the reading circuit relative to the sensing circuit is to place the reading side capacitor C r , reading side inductance L r , and the sensing side capacitance C s , sensing side inductance L s And the internal resistance R of the network vector analyzer on the reading side r , the sensor resistance R s Substituting into the equation: According to the mutual inductance coupling coefficient κ as the critical point The value of is determined.

[0008] Preferably, the derivation process of the non-Hermitian critical point is: according to the coupled mode theory, the eigenvalue equation of the wireless sensor circuit system is In the formula Where ω is the system characteristic frequency; ω0 is the natural resonant frequency of the LC resonator and the system characteristic frequency, κ is the mutual inductance coupling coefficient; g is the normalized gain parameter, γ is the normalized loss parameter, In order to obtain the critical point, let the system eigenvalue equation λ = 0, and the critical point can be obtained. The critical point only requires reading the planar inductor L in the circuit. r and the capacitance element C r The resonant frequency of the parameters and the planar inductor L in the sensing circuit s , Capacitive sensor C s The resonant frequencies are equal, that is No need to make the sensor resistor R s The internal resistance R of the network vector analyzer on the reading side r The gain parameter g can be greater than or less than the loss γ, and there is no need to fine-tune the reading part capacitance during the sensing process.

[0009] Preferably, the capacitive sensor is a capacitive sensor based on an interdigital electrode structure, such as a proximity sensor, a pressure sensor, a gas sensor, a humidity sensor, a temperature sensor, a displacement sensor, an acceleration sensor, etc.

[0010] Preferably, the coaxial connector is an ultra-miniature Type A interface.

[0011] The present invention also provides a method for manufacturing the aforementioned wireless sensor circuit based on a non-Hermitian critical point, comprising the following steps:

[0012] S1: Make a sensing circuit: Design a planar inductor coil L using a printed circuit board or flexible substrate s , and the capacitance sensor C s With the planar inductor L s Series connection;

[0013] S2: Make a reading circuit: Design a planar inductor coil L using a printed circuit board or flexible substrate r , while the capacitor element C r With the planar inductor L r In series, the capacitor element C r and planar inductor L r The parameter of is equal to the resonant frequency of the sensing circuit in S1, that is, And use coaxial connector to connect the series capacitor element C r With the planar inductor L r Connect with network vector analyzer;

[0014] S3: Determine the placement of the read circuit: Place the read side capacitor C r , reading side inductance L r and the sensing side capacitor C s , sensing side inductance L s And the internal resistance R of the network vector analyzer on the reading side r , the sensor resistance R s Substitute into the equation According to the mutual inductance coupling coefficient κ as the critical point The value of is determined.

[0015] Preferably, the type of the capacitive sensor in S1 is a capacitive sensor such as proximity sensor, pressure sensor, gas sensor, temperature sensor, humidity sensor, displacement sensor, acceleration sensor, etc. based on an interdigital electrode structure.

[0016] Preferably, the coaxial connector in S2 is an ultra-small type A interface.

[0017] The beneficial effects of the present invention are as follows:

[0018] The present invention provides a wireless sensor circuit based on non-Hermitian critical point, the circuit includes a sensing circuit and a reading circuit, and is characterized in that the sensing circuit includes: a planar inductor coil L s , Capacitive sensor C s , the capacitive sensor C s With the planar inductor L s in series, the capacitive sensor C s The interdigital electrode structure is adopted; the reading circuit includes a planar inductor coil L r , capacitor element C r , coaxial connector, network vector analyzer, the planar inductor coil L r and the capacitance element C r The network vector analyzer is connected in series with a planar inductor coil L through a coaxial connector. r and the capacitance element C r The non-Hermitian critical point of the wireless sensor circuit is the mutual inductance coupling coefficient The position of the reading circuit relative to the sensing circuit is to place the reading side capacitor C r , reading side inductance L r , and the sensing side capacitance C s , sensing side inductance L s And the internal resistance R of the network vector analyzer on the reading side r , the sensor resistance R s Substituting into the equation: According to the mutual inductance coupling coefficient κ as the critical point The value of is determined.

[0019] The present invention establishes a fixed correlation between the parameters of the sensing circuit and the reading circuit. Compared with the traditional design architecture, the wireless sensor design architecture based on the non-Hermitian critical point provided by the present invention works at the critical point, and the imaginary part of the characteristic frequency is zero. Therefore, the quality factor of the sensor is significantly improved, and the sensitivity is also higher than that of the traditional architecture. When the gain parameter g approaches the loss parameter γ, the sensitivity can be further improved. Compared with the architecture based on parity symmetry, on the one hand, the wireless sensor design architecture based on the non-Hermitian critical point provided by the present invention only requires the planar inductor coil L in the reading circuit. r and the capacitance element C r The resonant frequency of the parameters and the planar inductor L in the sensing circuit s , Capacitive sensor C s The resonant frequencies are equal, that is There is no need to strictly equalize gain and loss parameters and related electrical parameters, which improves the flexibility of sensor design. On the other hand, during the sensing process, there is no need to spend extra time manually or through complex electrical modules to fine-tune the capacitance of the reading part to ensure the symmetry of the system, thereby realizing real-time monitoring of the signal and avoiding inaccurate readings or errors caused by fine adjustments. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 :Schematic diagram of wireless sensor circuit design based on non-Hermitian critical point. DETAILED DESCRIPTION

[0021] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the wireless sensor circuit and manufacturing method based on non-Hermitian critical points proposed by the present invention are further described in detail below in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are in a very simplified form and are not in exact proportions. They are only used to conveniently and clearly assist in illustrating the objectives of the embodiments of the present invention. To make the objectives, features, and advantages of the present invention more clearly understood, please refer to the drawings. It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read. They are not intended to limit the conditions for the implementation of the present invention and therefore have no technical significance. Any structural modifications, changes in proportional relationships, or adjustments in size should still fall within the scope of the technical content disclosed in the present invention without affecting the efficacy and objectives that can be achieved by the present invention.

[0022] The circuit on the right side of the figure is a sensing circuit, including a planar inductor coil L s (Inductance is L s ), capacitance sensor C s (The capacitance is C s, the internal resistance is R s ); The circuit on the left is the reading circuit, including: a planar inductor coil L r (Inductance is L r ), capacitor element C r (The capacitance is C r， The internal resistance is R r ), coaxial connectors, network vector analyzers.

[0023] According to the coupled mode theory, the eigenvalue equation of the circuit system in the figure is In the formula Where ω is the system characteristic frequency; is the natural resonant frequency of the LC resonator; κ is the mutual inductance coupling coefficient; is the normalized gain parameter; is the normalized loss parameter; C r , L r 、C s , L s Read the measured capacitance and inductance and the sensing side capacitance and inductance respectively; R r is the internal resistance of the network vector analyzer on the reading side, R s is the resistance of the sensor. In order to obtain the critical point, let the system eigenvalue equation λ=0, and the critical point can be obtained.

[0024] The technical solution of the present invention is described in detail below with reference to the accompanying drawings. The present invention provides a wireless sensor circuit based on a non-Hermitian critical point, the circuit comprising a sensing circuit and a reading circuit, characterized in that the sensing circuit comprises: a planar inductor coil L s , Capacitive sensor C s , the capacitive sensor C s With the planar inductor L s in series, the capacitive sensor C s The interdigital electrode structure is adopted; the reading circuit includes a planar inductor coil L r , capacitor element C r , coaxial connector, network vector analyzer, the planar inductor coil L r and the capacitance element C r The network vector analyzer is connected in series with a planar inductor coil L through a coaxial connector. r and the capacitance element C r The non-Hermitian critical point of the wireless sensor circuit is the mutual inductance coupling coefficient The position of the reading circuit relative to the sensing circuit is to place the reading side capacitor C r , reading side inductance L r , and the sensing side capacitance C s, sensing side inductance L s And the internal resistance R of the network vector analyzer on the reading side r , the sensor resistance R s Substituting into the equation: According to the mutual inductance coupling coefficient κ as the critical point The value of is determined.

[0025] In some embodiments of the present invention, the type of the capacitance sensor is a proximity capacitance sensor based on a forked electrode structure; in some embodiments of the present invention, the type of the capacitance sensor is a pressure sensor based on a forked electrode structure; in some embodiments of the present invention, the type of the capacitance sensor is a gas pressure capacitance sensor based on a forked electrode structure; in some embodiments of the present invention, the type of the capacitance sensor is a temperature capacitance sensor based on a forked electrode structure; in some embodiments of the present invention, the type of the capacitance sensor is a humidity sensor based on a forked electrode structure; in some embodiments of the present invention, the type of the capacitance sensor is a displacement sensor based on a forked electrode structure; in some embodiments of the present invention, the type of the capacitance sensor is an acceleration sensor based on a forked electrode structure.

[0026] In some embodiments of the present invention, the coaxial connector is a SubMiniature version A (SMA) interface.

[0027] In other embodiments of the present invention, the method for manufacturing the wireless sensor circuit based on the non-Hermitian critical point comprises the following steps:

[0028] S1: Make a sensing circuit: Design a planar inductor coil L using a printed circuit board or flexible substrate s , and the capacitance sensor C s With the planar inductor L s Series connection;

[0029] S2: Make a reading circuit: Design a planar inductor coil L using a printed circuit board or flexible substrate r , while the capacitor element C r With the planar inductor L r In series, the capacitor element C r and planar inductor L r The parameter of is equal to the resonant frequency of the sensing circuit in S1, that is, And use coaxial connector to connect the series capacitor element C r With the planar inductor L r Connect with network vector analyzer;

[0030] S3: Determine the placement of the read circuit: Place the read side capacitor Cr , reading side inductance L r and the sensing side capacitor C s , sensing side inductance L s And the internal resistance R of the network vector analyzer on the reading side r , the sensor resistance R s Substitute into the equation According to the mutual inductance coupling coefficient κ as the critical point The value of is determined.

[0031] In some embodiments of the present invention, the type of the capacitance sensor in S1 is a proximity capacitance sensor based on an interdigitated electrode structure; in some embodiments of the present invention, the type of the capacitance sensor in S1 is a pressure sensor based on an interdigitated electrode structure; in some embodiments of the present invention, the type of the capacitance sensor in S1 is a gas pressure capacitance sensor based on an interdigitated electrode structure; in some embodiments of the present invention, the type of the capacitance sensor in S1 is a temperature capacitance sensor based on an interdigitated electrode structure; in some embodiments of the present invention, the type of the capacitance sensor in S1 is a humidity sensor based on an interdigitated electrode structure; in some embodiments of the present invention, the type of the capacitance sensor in S1 is a displacement sensor based on an interdigitated electrode structure; in some embodiments of the present invention, the type of the capacitance sensor in S1 is an acceleration sensor based on an interdigitated electrode structure.

[0032] In some embodiments of the present invention, the coaxial connector in S2 is a SubMiniature version A (SMA) interface.

[0033] After designing and deploying the wireless sensor based on the non-Hermitian critical point method according to the above-described embodiment, it can be used for sensing. Changes in the external measured value will cause changes in the capacitance on the sensing side, which in turn causes a shift in the sensor's characteristic frequency. The corresponding reflection coefficient spectrum can be read using a network vector analyzer, and the corresponding characteristic frequency can be analyzed to obtain the final test results.

[0034] The technical features of the above-described embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification. The above-described embodiments only express one embodiment of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as a limitation on the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present invention, several variations and improvements can be made, which all fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent of the present invention shall be based on the attached claims.

Claims

1. A wireless sensor circuit based on a non-Hermitian critical point, the circuit comprising a sensing circuit and a reading circuit, characterized in that The sensing circuit includes: a planar inductor coil L s , Capacitive sensor C s , the capacitive sensor C s With the planar inductor L s in series, the capacitive sensor C s Adopting the interdigital electrode structure; the reading circuit includes a planar inductor coil L r , capacitor element C r , coaxial connector, network vector analyzer, the planar inductor coil L r and the capacitance element C r The network vector analyzer is connected in series with a planar inductor coil L through a coaxial connector. r and the capacitance element C r The non-Hermitian critical point of the wireless sensor circuit is the mutual inductance coupling coefficient g is the normalized gain parameter, γ is the normalized loss parameter; and the position of the reading circuit relative to the sensing circuit is to place the reading side capacitor C r , reading side inductance L r , and the sensing side capacitance C s , sensing side inductance L s And the internal resistance R of the network vector analyzer on the reading side r , the sensor resistance R s Substituting into the equation: According to the mutual inductance coupling coefficient κ as the critical point The critical point only requires reading the planar inductor L in the circuit. r and the capacitance element C r The resonant frequency of the parameters and the planar inductor L in the sensing circuit s , Capacitive sensor C s The resonant frequencies are equal, that is No need to make the sensor resistor R s The internal resistance R of the network vector analyzer on the reading side r The gain parameter g can be greater than or less than the loss γ, and there is no need to fine-tune the reading part capacitance during the sensing process.

2. The wireless sensor circuit based on non-Hermitian critical point according to claim 1, characterized in that: The derivation process of the non-Hermitian critical point is as follows: According to the coupling model theory, the eigenvalue equation of the wireless sensor circuit system is: In the formula Where ω is the system characteristic frequency; ω0 is the natural resonant frequency of the LC resonator and the system characteristic frequency, κ is the mutual inductance coupling coefficient; in order to obtain the critical point, let the system eigenvalue equation λ = 0, and the critical point can be obtained 3. A wireless sensor circuit based on non-Hermitian critical points according to claim 1 or 2, characterized in that: The capacitive sensor C s The type is a capacitive sensor for proximity, pressure, gas, humidity, temperature, displacement or acceleration based on an interdigitated electrode structure.

4. The wireless sensor circuit based on non-Hermitian critical point according to claim 3, characterized in that: This coaxial connector is a subminiature Type A interface.

5. The method for manufacturing a wireless sensor circuit based on a non-Hermitian critical point according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1: Make a sensing circuit: Design a planar inductor coil L using a printed circuit board or flexible substrate s , and the capacitance sensor C s With the planar inductor L s Series connection; S2: Make a reading circuit: Design a planar inductor coil L using a printed circuit board or flexible substrate r , while the capacitor element C r With the planar inductor L r in series, the capacitive element C r and planar inductor L r The parameter of is equal to the resonant frequency of the sensing circuit in S1, that is, And use coaxial connector to connect the series capacitor element C r With the planar inductor L r Connect with network vector analyzer; S3: Determine the placement of the read circuit: Place the read side capacitor C r , reading side inductance L r and the sensing side capacitor C s , sensing side inductance L s And the internal resistance R of the network vector analyzer on the reading side r , the sensor resistance R s Substituting into the equation: According to the mutual inductance coupling coefficient κ as the critical point The value is determined.

6. The method for manufacturing a wireless sensor circuit based on a non-Hermitian critical point according to claim 5, characterized in that: The capacitance sensor C in S1 s The type is a capacitive sensor for proximity, pressure, gas, temperature, humidity, displacement or acceleration based on an interdigitated electrode structure.

7. The method for manufacturing a wireless sensor circuit based on a non-Hermitian critical point according to claim 6 or 5, characterized in that: The coaxial connector in the S2 is an ultra-small type A interface.

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