A high-precision humidity sensor based on high-order non-Hermitian circuits

Abstract

This invention discloses a high-precision humidity sensor based on a high-order non-Hermitian circuit, belonging to the field of electronic sensor technology. It includes a capacitive humidity sensor, an LM6171 high-speed non-inverting amplifier, and passive components. The passive components include a left LC resonator and a right LC resonator, with the capacitive humidity sensor connected between them. The left and right LC resonators are respectively connected to a positive resistor R and a voltage source V. g Voltage source internal resistance Z0, resistor R0, resistor R f It is connected in parallel with an equivalent circuit containing an LM6171 high-speed non-inverting amplifier. This invention provides a high-precision humidity sensor based on a high-order non-Hermitian circuit, offering high accuracy, high stability, and low cost. The dielectric layer of the humidity capacitive sensor is fabricated using a PMDA / ODA / PAN / TiO2 polymer composite material, exhibiting high stability, good linearity, and low hysteresis. Furthermore, the non-Hermitian circuit offers high efficiency, high flexibility, and strong freedom and adjustability, enabling high-precision sensing and measurement of disturbances caused by changes in ambient humidity.

Description

Technical Field

[0001] This invention relates to the field of electronic sensor technology, and in particular to a high-precision humidity sensor based on a high-order non-Hermitian circuit. Background Technology

[0002] A humidity sensor is a load device that converts the humidity level into a measurable electrical, optical, or thermal signal by adsorbing or desorbing water molecules from an object's surface or the environment. High-precision capacitive humidity sensors are commonly used to measure humidity in the air, utilizing the property that the dielectric constant between the two plates of a capacitor is proportional to the humidity in the air. As the humidity in the air increases, the dielectric constant increases, and the capacitance of the capacitor changes accordingly. By measuring the capacitance value, the humidity in the air can be determined.

[0003] Currently, mainstream humidity sensors on the market achieve an accuracy within ±2% RH (relative humidity), making them suitable for many fields. For example, they can be used in constant temperature and humidity chambers to monitor changes in ambient humidity; in the food industry to monitor humidity during food processing, preventing food damage due to excessively high or low humidity; and in meteorological monitoring for weather changes and meteorological research. However, existing humidity sensors still suffer from low sensitivity: traditional humidity sensors respond slowly to changes in ambient humidity, cannot quickly reflect changes in humidity levels, and have relatively large errors.

[0004] Suitable humidity-sensitive materials are crucial for achieving high-performance humidity sensors. Humidity-sensitive polymers, due to their hydrophilicity, porous structure, and size and pore size distribution, can improve the sensitivity of the sensing response. The MIM-type capacitive humidity sensor consists of two metal electrodes and a dielectric layer. One metal electrode serves as a vent, while the other is covered with a moisture-absorbing material. The porous MIM-type capacitive humidity detection unit, with its porous top electrode, increases the contact area between water molecules and the humidity-sensitive polymer material, enhancing the diffusion of moisture into the polymer sensing layer. This structural characteristic improves the accuracy of humidity detection. Summary of the Invention

[0005] The purpose of this invention is to provide a high-precision humidity sensor based on a high-order non-Hermitian circuit, which solves the problems of slow response speed to changes in humidity in the environment, inability to quickly reflect changes in humidity in the environment, and large errors.

[0006] To achieve the above objectives, the present invention provides a high-precision humidity sensor based on a high-order non-Hermitian circuit, comprising a capacitive humidity sensor, an LM6171 high-speed non-inverting amplifier, and passive components. The passive components include a left LC resonator and a right LC resonator, with the capacitive humidity sensor connected between the left and right LC resonators. The left and right LC resonators are respectively connected to a positive resistor R and a voltage source V. g Voltage source internal resistance Z0, resistor R0, resistor R f It is connected in parallel with the equivalent circuit containing the LM6171 high-speed non-inverting amplifier.

[0007] Preferably, the equivalent circuit includes the LM6171 high-speed non-inverting amplifier, which is connected to another positive resistor R and R1 respectively. g in parallel.

[0008] Preferably, the capacitive humidity sensor includes an upper electrode layer, a dielectric layer, a lower electrode layer, and a base layer, wherein the upper electrode layer is connected to the dielectric layer, the dielectric layer is connected to the lower electrode layer, and the lower electrode layer is connected to the base layer.

[0009] Preferably, the upper electrode layer has a plurality of through holes arranged at equal intervals and uniformly.

[0010] Preferably, the aperture S of the through hole is 20 μm, the through hole spacing is 10 μm, and the ratio between the upper electrode layer and the through hole is 5:3.

[0011] Preferably, the dielectric layer is a PMDA / ODA / PAN / TiO2 polymer composite humidity-sensitive material.

[0012] Preferably, the base layer is a glass substrate.

[0013] Therefore, the high-precision humidity sensor based on a high-order non-Hermitian circuit using the above structure of the present invention has the following beneficial effects:

[0014] (1) Use MIM type capacitive humidity detection unit. This sensor has high accuracy, high stability and low cost, and is suitable for practical use.

[0015] (2) The dielectric layer of the humidity capacitive sensor is prepared by using PMDA / ODA / PAN / TiO2 polymer composite material, which has high stability, good linearity and low hysteresis;

[0016] (3) The top metal electrode of the humidity capacitance detection unit is a perforated electrode with small pore size and pore spacing, resulting in a large contact area between the dielectric layer and moisture and good moisture absorption effect.

[0017] (4) Use the LM6171 amplifier to construct an equivalent circuit with a negative resistance of -R. This amplifier has high speed response and low noise performance, high input impedance and high output current, and is suitable for constructing an equivalent circuit with a negative resistance.

[0018] (5) The high-precision capacitive humidity sensor is used in a non-Hermitian circuit structure. Non-Hermitian circuits are highly efficient, flexible, free, and adjustable, meeting the needs of practical applications and enabling high-precision sensing and measurement of disturbances caused by changes in ambient humidity.

[0019] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0020] Figure 1 This is a circuit diagram of a high-precision humidity sensor based on a high-order non-Hermitian circuit according to the present invention.

[0021] Figure 2 The present invention provides an equivalent circuit diagram of a high-precision humidity sensor based on a high-order non-Hermitian circuit, which utilizes an LM6171 amplifier to achieve negative resistance.

[0022] Figure 3 The negative impedance IV curve of the equivalent circuit of negative resistance is shown in the figure, which is used by the LM6171 amplifier to realize the negative resistance of a high-precision humidity sensor based on a high-order non-Hermitian circuit according to the present invention.

[0023] Figure 4 The present invention provides a capacitive humidity sensing characteristic diagram and linear fitting of a PMDA / ODA / PAN / TiO2 polymer composite humidity sensing material for a high-precision humidity sensor based on a high-order non-Hermitian circuit.

[0024] Figure 5 This is a side view of the structure of a MIM (metal-insulator-metal) type humidity capacitive sensor, a high-precision humidity sensor based on a high-order non-Hermitian circuit, according to the present invention.

[0025] Figure 6 This is a schematic diagram of the structure of a modified capacitive humidity sensor based on a high-precision humidity sensor of a high-order non-Hermitian circuit according to the present invention.

[0026] Figure 7 This is a schematic diagram of the perforated metal electrode structure on the top of the MIM-type capacitive humidity detection unit of a high-precision humidity sensor based on a high-order non-Hermitian circuit according to the present invention.

[0027] Figure 8 To illustrate the humidity variation in the range of 10%RH to 90%RH using a high-precision humidity sensor based on a high-order non-Hermitian circuit, the return loss coefficient S of the non-Hermitian circuit is... 11 Relationship with resonant frequency;

[0028] Figure 9 This is a comparison chart of the capacitance accuracy of a high-precision humidity sensor based on a high-order non-Hermitian circuit of the present invention when the ambient humidity is 10%RH.

[0029] Figure 10 This is a comparison chart of the capacitance accuracy of a high-precision humidity sensor based on a high-order non-Hermitian circuit of the present invention when the ambient humidity is 90%RH.

[0030] Figure Labels

[0031] 1. Upper electrode layer, 2. Dielectric layer, 3. Lower electrode layer, 4. Base layer. Detailed Implementation

[0032] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0033] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0034] Example 1

[0035] This invention provides a high-precision humidity sensor based on a high-order non-Hermitian circuit, comprising a capacitive humidity sensor, an LM6171 high-speed non-inverting amplifier, and passive components. The passive components include a left LC resonator and a right LC resonator, with the capacitive humidity sensor connected between them. The left and right LC resonators are respectively connected to a positive resistor R and a voltage source V. g Voltage source internal resistance Z0, resistor R0, resistor R f It is connected in parallel with an equivalent circuit containing an LM6171 high-speed non-inverting amplifier. The equivalent circuit includes an LM6171 high-speed non-inverting amplifier, which is connected in parallel with another positive resistor R and R. gThe capacitive humidity sensor is connected in parallel. It includes an upper electrode layer 1, a dielectric layer 2, a lower electrode layer 3, and a base layer 4. The upper electrode layer 1 is connected to the dielectric layer 2, the dielectric layer 2 is connected to the lower electrode layer 3, and the lower electrode layer 3 is connected to the base layer 4. The upper electrode layer 1 has several evenly spaced through-holes. The diameter S of the through-holes is 20 μm, the through-hole spacing is 10 μm, and the ratio between the upper electrode layer 1 and the through-holes is 5:3. The dielectric layer 2 is a PMDA / ODA / PAN / TiO2 polymer composite humidity-sensitive material. The base layer 4 is a glass substrate.

[0036] Combination Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 , Figure 8 , Figure 9 and Figure 10 A high-precision humidity sensor based on a high-order non-Hermitian circuit consists of a non-Hermitian circuit structure and a capacitive humidity sensing unit. The non-Hermitian circuit structure comprises two pairs of LC resonators connected to the capacitive humidity sensor C0, with a 618Ω resistor R connected in parallel on the left and an equivalent circuit with negative impedance, constructed from an LM6171 high-speed non-inverting amplifier, connected in parallel on the right. In the sub-circuit centered on the LM6171 high-speed non-inverting amplifier, the equivalent negative impedance is... R f R g Both are 1Ω, R is 618Ω, and the equivalent negative resistance can be approximated as -618Ω by ΔV / ΔI. The inductance L of the LC resonator is 100μF, the capacitance C is 100pF, and the voltage source V... g The internal resistance Z0 is 50Ω, and the resistance R0 is 50Ω. The humidity-sensitive capacitor can change its capacitance value under a certain range of relative humidity. By changing the relative humidity in the environment, the hygroscopic characteristics of the PMDA / ODA / PAN / TiO2 polymer composite humidity-sensitive material allow the capacitance value to change approximately linearly from 240pF to 323pF under humidity changes ranging from 10%RH to 90%RH. In the non-Hermitian circuit, the resonant frequency changes from 1.339MHz to 334.4KHz within a wide humidity range of 10%RH to 90%RH, with an average change of 12.56KHz per 1%RH. The humidity sensitivity of the resonant frequency is 12.56KHz / %RH; the return loss coefficient S... 11 The humidity changed from -162.5dB to -128.5dB, with a humidity sensitivity of 0.425dB / %RH. Figure 8 This is the result of the capacitive humidity sensing unit under a non-Hermitian circuit structure.

[0037] Example 2

[0038] Combination Figure 1 , Figure 4 , Figure 8 and Figure 9 A high-precision humidity sensor based on a high-order non-Hermitian circuit is composed of a non-Hermitian circuit structure and a capacitive humidity sensing unit. A high-precision humidity capacitive sensing unit with dimensions of 4mm × 5mm is designed based on a MIM-type capacitor structure and applied to the non-Hermitian circuit structure. The top metal electrode of the humidity capacitive sensing unit is a perforated electrode with a aperture S of 20μm and a hole spacing D of 10μm, with a ratio of approximately 5:3 between the top metal and the hole. The resonant frequencies of the humidity-sensitive capacitor in 10% RH and 90% RH environments are 334.4kHz and 1.339MHz, respectively. At 10% RH, the capacitance of the humidity-sensitive capacitor is 240pF. Increasing the capacitance by 0.1pF results in a higher S at 1.339MHz. 11 The change from -131.6dB to -145.9dB is much greater than -3dB, and the hysteresis coefficient is less than 0.104%RH.

[0039] Example 3

[0040] Combination Figure 1 , Figure 4 and Figure 10 A high-precision humidity sensor based on a high-order non-Hermitian circuit consists of a non-Hermitian circuit structure and a capacitive humidity sensing unit. At an ambient humidity of 90% RH, the capacitance of the humidity sensor is 323 pF. Increasing the capacitance by 0.1 pF results in a higher Si at 1.339 MHz. 11 When the voltage changes from -182.2dB to -206.8dB, the capacitance increases by 0.01pF at this point. 11 When the capacitance changes from -182.2dB to -190.0dB, an increase of 0.01pF results in a change in the return loss coefficient greater than -3dB and a hysteresis coefficient less than 0.0104%RH.

[0041] Therefore, this invention employs a high-precision humidity sensor based on a high-order non-Hermitian circuit, which offers high accuracy, high stability, and low cost. The dielectric layer of the humidity capacitive sensor is fabricated using a PMDA / ODA / PAN / TiO2 polymer composite material, exhibiting high stability, good linearity, and low hysteresis. Furthermore, the non-Hermitian circuit offers high efficiency, high flexibility, and strong freedom and adjustability, meeting the needs of practical applications and enabling high-precision sensing and measurement of disturbances caused by changes in environmental humidity.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A high-precision humidity sensor based on high-order non-Hermite circuit, comprising a capacitive humidity sensor, a LM6171 high-speed in-phase amplifier and passive elements, characterized in that: The passive element includes a left LC resonator and a right LC resonator, the left LC resonator and the right LC resonator are connected with the capacitive humidity sensor, the left LC resonator and the right LC resonator are respectively connected with a positive resistance R, a voltage source V g , a voltage source internal resistance Z0, a resistance R0, a resistance R f And the equivalent circuit containing the LM6171 high-speed balanced amplifier are connected in parallel; The capacitive humidity sensor comprises an upper electrode layer, a medium layer, a lower electrode layer and a base layer, the upper electrode layer is connected with the medium layer, the medium layer is connected with the lower electrode layer, and the lower electrode layer is connected with the base layer; The medium layer is a PMDA / ODA / PAN / TiO2 polymer composite humidity-sensitive material, and the base layer is a glass substrate; The equivalent circuit comprises the LM6171 high-speed balanced amplifier, the LM6171 high-speed balanced amplifier being connected in parallel with another positive resistor R and R g respectively.

2. The high-precision humidity sensor based on high-order non-Hermite circuit according to claim 1, characterized in that: A plurality of equidistant and uniformly arranged through holes are formed in the upper electrode layer.

3. The high-precision humidity sensor based on high-order non-Hermite circuit according to claim 2, characterized in that: The through hole aperture S is , the through hole pitch is , and the ratio between the upper electrode layer and the through hole is 5:3.

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