WO2020077627A1 - Acoustic fluid sensor - Google Patents

Abstract

Disclosed is an acoustic fluid sensor, comprising an acoustic sensing apparatus, an experimental container, an ultrasonic transmission apparatus, an ultrasonic receiving apparatus and a computing processing apparatus, wherein the acoustic sensing apparatus comprises a hollow cylindrical housing for containing load fluid, and silica gel tubes arranged at two ends of the hollow cylindrical housing and forming a penetrated cavity channel with the hollow cylindrical housing; the ultrasonic transmission apparatus transmits an ultrasonic wave to environment fluid to excite the load fluid in the hollow cylindrical housing to form a Scholte-Stoneley circumferential wave, and when the Scholte-Stoneley circumferential wave satisfies a phase matching condition, standing waves are formed surrounding the hollow cylindrical housing to generate a local sound field; and the computing processing apparatus determines a quality factor of the acoustic fluid sensor according to normalized transmission spectrum data. The local sound field generated in the present invention has a relatively high coupling degree with the load fluid, which can improve the quality factor and the sensitivity of the acoustic fluid sensor, and is suitable for high-sensitive sensing of trace fluid.

Description

Acoustic fluid sensor Technical field

The invention relates to the technical field of fluid detection, in particular to an acoustic fluid sensor.

Background technique

In the fields of biochemical detection, clinical medicine, environmental monitoring and food safety monitoring, the use of acoustic fluid sensors to quickly and accurately detect fluid parameters (such as composition, density, elastic modulus, sound velocity and viscosity, etc.) has important application value. Acoustic fluid sensors change in the properties (such as mechanical, chemical, and electrical properties) of the surrounding fluid medium, and can detect shifts in resonance modes such as frequency, amplitude, and phase to realize fluid sensing and detection.

Existing acoustic fluid sensors mainly include surface wave sensors, Lamb wave sensors and phononic crystal sensors. The surface wave fluid sensor uses the wave propagating on the surface of the piezoelectric substrate, and detects the parameter to be measured by the physical and chemical parameters disturbing the propagation characteristics of the acoustic wave. The Lamb wave sensor utilizes the sound wave of the Lamb wave propagating in the thin plate, and is excited by the interdigital transducer placed on one surface of the piezoelectric thin plate and propagates in the piezoelectric thin plate. Acoustic artificial structures (phonon crystals, acoustic metamaterials, etc.) are artificially designed composite structural materials that utilize the effects of Bragg scattering in periodic structures and local resonance in single structures to achieve flexible control of acoustic and elastic waves It is a research hotspot that has received much attention in the fields of physics and materials science in recent years. The relevant physical properties of the acoustic artificial structure can be "manually tailored", which provides a solid physical foundation for the development of new functional devices. Highly sensitive sensors are a major application direction of acoustic artificial structures in new functional devices. At present, it has been proposed to use phonon crystal defect states, periodic round-hole phononic crystal plate anomalous transmission enhancement peaks, and phononic crystal resonant cavity mode for acoustic fluid sensors to realize the detection of fluids.

But the traditional acoustic fluid sensor has the defects of low quality factor and low sensitivity.

Summary of the invention

An embodiment of the present invention provides an acoustic fluid sensor to solve the defect of low quality factor existing in a conventional acoustic fluid sensor. The acoustic fluid sensor includes:

Acoustic sensing device, experimental container, ultrasonic transmitting device, ultrasonic receiving device and computing processing device;

The acoustic sensing device includes a hollow cylindrical shell for containing a load fluid, and a silicone tube provided at both ends of the hollow cylindrical shell and forming a through cavity therewith;

The experimental container is used to contain environmental fluid, the hollow cylindrical shell is immersed in the environmental fluid, and the acoustic sensing device is disposed between the ultrasonic transmitting device and the ultrasonic receiving device;

The ultrasonic wave emitting device emits ultrasonic waves into the environmental fluid to excite the load fluid in the hollow cylindrical shell to form a Scholte-Stoneley circumferential wave. When the Scholte-Stoneley circumferential wave satisfies the phase matching condition, the hollow A standing wave is formed around the cylindrical shell to generate a local sound field, and the ultrasonic receiving device receives ultrasonic waves after passing through the acoustic sensing device;

The calculation processing device determines the normalized transmission spectrum data according to the first transmission spectrum data and the second transmission spectrum data, and determines the quality factor of the acoustic fluid sensor according to the normalized transmission spectrum data; wherein, the The first transmission spectrum data refers to the transmission spectrum data of the ultrasonic waves received by the ultrasonic receiving device when the acoustic sensing device and the load fluid are not included, and the second transmission spectrum data includes the acoustic sensing device and the load fluid The transmission spectrum data of the ultrasonic wave received by the ultrasonic receiving device at that time.

In the embodiment of the present invention, the acoustic fluid sensor includes an acoustic sensing device, an experimental container, an ultrasonic transmitting device, an ultrasonic receiving device, and a calculation processing device; the acoustic sensing device includes a hollow cylindrical housing for containing a load fluid, and a Silicone tubes at both ends of the hollow cylindrical shell and forming a through cavity therethrough. In the embodiment of the present invention, an ultrasonic wave transmitting device is used to transmit ultrasonic waves to the environmental fluid to excite the load fluid in the hollow cylindrical shell to form a Scholte-Stoneley circumferential wave. When the Scholte-Stoneley circumferential wave satisfies the phase matching condition, the hollow cylindrical shell A local sound field is generated around the standing wave, and the local sound field generated at this time has a greater degree of coupling with the load fluid. Therefore, the quality factor and sensitivity of the acoustic fluid sensor can be improved, which is suitable for highly sensitive sensing of trace fluids.

BRIEF DESCRIPTION

In order to more clearly explain the technical solutions in the embodiments of the present invention, the drawings required in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For a person of ordinary skill in the art, without paying any creative work, other drawings can also be obtained based on these drawings. In the drawings:

1 is a functional block diagram of an acoustic fluid sensor provided by an embodiment of the present invention;

2 is a schematic diagram of an acoustic fluid sensor provided by an embodiment of the present invention;

3 shows a schematic diagram of the phase velocity dispersion curve of the Scholte-Stoneley circumferential wave provided by an embodiment of the present invention;

4 is a schematic diagram of the resonance sound pressure field distribution in FIG. 3 where b: a is a 4: 5 phase velocity dispersion curve with different circumferential resonance modes n = 2-6;

5a is a three-dimensional schematic diagram of a hollow cylindrical housing of an acoustic fluid sensor according to an embodiment of the present invention;

5b is a schematic plan view of a hollow cylindrical housing of an acoustic fluid sensor provided by an embodiment of the present invention;

6a-6d are schematic diagrams of the relationship between the solution concentration, density, and sound velocity of the four standard fluids of sample 1, sample 2, sample 3, and NaI solution provided by embodiments of the present invention;

7 is a schematic diagram of the relationship between the solution concentration and resonance frequency of four different standard fluids provided by an embodiment of the present invention;

8 is a schematic diagram of the resonance frequency and the transmission amplitude of the NaI solution simulated by the solution at different solution concentrations provided by an embodiment of the present invention;

FIG. 9 is a schematic diagram of the resonance frequency and the transmission amplitude of the NaI solution provided by the embodiment of the present invention at different solution concentrations in actual experiments.

detailed description

To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the embodiments of the present invention are described in further detail below with reference to the accompanying drawings. Here, the exemplary embodiments of the present invention and the description thereof are used to explain the present invention, but are not intended to limit the present invention.

Principle of invention

During the experiment, a load fluid was injected into the hollow cylindrical shell. When a plane harmonic of a certain eigenfrequency was incident on the finite length hollow cylindrical shell perpendicular to the axis, the load fluid inside the hollow cylindrical shell (standard fluid or to be measured) (Fluid) excites the Scholte-Stoneley circumferential wave that circulates along the hollow cylindrical shell. When the phase velocity of the Scholte–Stoneley circumferential wave satisfies the phase matching condition, the Scholte–Stoneley circumferential wave will form a standing wave in the circumferential direction of the hollow cylindrical shell, thereby generating a localized strong field around the hollow cylindrical shell. The larger the ratio of the inner diameter to the outer diameter of the hollow cylindrical shell, that is, the thinner the hollow cylindrical shell, the greater the coupling between the local sound field and the load fluid, and the stronger the strength of the local sound field. Therefore, it is only necessary to inject a small amount of fluid (loaded fluid, that is, standard fluid or fluid to be measured) into the hollow cylindrical shell to obtain a strong local sound field, so the quality factor of the acoustic fluid sensor is higher and the sensitivity (ie The better the maximum offset value of the resonance frequency), the more suitable it is for highly sensitive sensing of trace fluids. The inner diameter and outer diameter of the hollow cylindrical shell, the strong local sound field, and the interaction of ultrasonic waves and matter determine the changes in fluid density and acoustic velocity (especially the changes in density) of the acoustic fluid sensor system of the hollow cylindrical shell structure. ) Is more sensitive. When a fluid with a significant density change is selected, the resonance transmission peak will shift significantly. Therefore, the acoustic fluid sensor with a hollow cylindrical shell structure has a high sensitivity. Using the strong local sound field of the hollow cylindrical shell structure, the application of the hollow cylindrical shell structure to the new highly sensitive and trace fluid sensors can be realized.

FIG. 1 shows a functional module of an acoustic fluid sensor provided by an embodiment of the present invention. For ease of description, only parts related to the embodiment of the present invention are shown. The details are as follows:

As shown in FIG. 1, the acoustic fluid sensor includes an acoustic sensing device, an experimental container, an ultrasonic transmitting device, an ultrasonic receiving device, and a calculation processing device.

The acoustic sensing device includes a hollow cylindrical shell for containing a load fluid, and a silicone tube provided at both ends of the hollow cylindrical shell and forming a through cavity therewith. When determining the quality factor of the acoustic fluid sensor, the load fluid is a standard fluid with known parameters, and the standard fluid is used to determine the relationship between the resonance frequency and the fluid density or fluid concentration. After using the standard fluid with known parameters to determine the relationship between the resonance frequency and the fluid density or fluid concentration, the density and concentration of the fluid to be measured can be inferred based on the measured resonance frequency of the fluid to be measured. The standard fluid may be water, NaI solution (sodium iodide solution), or other mixed solutions.

The experimental container is used to contain environmental fluid, the hollow cylindrical shell is immersed in the environmental fluid, and the acoustic sensing device is disposed between the ultrasonic transmitting device and the ultrasonic receiving device. The environmental fluid may be water, NaI solution (sodium iodide solution), or other mixed solutions.

The ultrasonic wave emitting device emits ultrasonic waves into the environmental fluid to excite the load fluid in the hollow cylindrical shell to form a Scholte-Stoneley circumferential wave. When the Scholte-Stoneley circumferential wave satisfies the phase matching condition, the hollow A standing wave is formed around the cylindrical shell to generate a local sound field, and the ultrasonic receiving device receives ultrasonic waves passing through the acoustic sensing device.

The calculation processing device determines the normalized transmission spectrum data according to the first transmission spectrum data and the second transmission spectrum data, and determines the quality factor of the acoustic fluid sensor according to the normalized transmission spectrum data; wherein, the The first transmission spectrum data refers to the transmission spectrum data of the ultrasonic waves received by the ultrasonic receiving device when the acoustic sensing device and the load fluid are not included, and the second transmission spectrum data includes the acoustic sensing device and the load fluid The transmission spectrum data of the ultrasonic wave received by the ultrasonic receiving device at that time.

The working principle of the acoustic fluid sensor is: under the excitation of ultrasonic waves, the load fluid in the hollow cylindrical shell forms a Scholte-Stoneley circumferential wave. When the Scholte-Stoneley circumferential wave satisfies the phase matching condition, the hollow cylindrical shell A standing wave is formed around the body to generate a local sound field, and the ultrasonic wave passing through the hollow cylindrical shell has a resonance transmission peak in the frequency spectrum. Acquiring first transmission spectrum data of ultrasonic waves received by the ultrasonic receiving device when the acoustic sensing device and the fluid are not loaded, and acquiring second ultrasonic waves received by the ultrasonic receiving device when the acoustic sensing device and the fluid are loaded Transmission spectrum data, normalizing the first transmission spectrum data and the second transmission spectrum data to determine the normalized transmission spectrum data, and then determining the quality factor of the acoustic fluid sensor according to the normalized transmission spectrum data .

When determining the quality factor of the acoustic fluid sensor, the load fluid is a standard fluid with known parameters, and the standard fluid is used to confirm the relationship between the resonance frequency and the fluid density or fluid concentration. After using the standard fluid with known parameters to determine the relationship between the resonance frequency and the fluid density or fluid concentration, the density and concentration of the fluid to be measured can be inferred based on the measured resonance frequency of the fluid to be measured. That is, the resonance frequency of the acoustic fluid sensor is measured using a standard fluid with known parameters, and then the fluid to be measured is injected into the hollow cylindrical housing, and the parameters of the fluid to be measured are inferred according to the resonance frequency.

Based on the working principle of the acoustic fluid sensor, it can be known that only under the excitation of ultrasonic waves, the loaded fluid in the hollow cylindrical shell forms a Scholte-Stoneley circumferential wave. When the Scholte-Stoneley circumferential wave satisfies the phase matching condition, the hollow A standing wave is formed around the cylindrical shell to generate a local sound field. The acoustic fluid sensor can achieve the purpose of detection only when the frequency spectrum of the ultrasonic wave passing through the hollow cylindrical shell has a resonance transmission peak.

In the course of studying the present invention, the inventor found that the frequency of ultrasonic waves, the structural size of the hollow cylindrical shell, and the parameters of the load fluid (standard fluid or fluid to be measured) contained in the hollow cylindrical shell are the factors that affect the hollow cylindrical shell Whether the body can form a Scholte-Stoneley circumferential wave and then form a standing wave around the hollow cylindrical shell to generate a localized sound field is also a key factor that affects whether resonance transmission peaks can appear in the spectrum after the ultrasound passes through the hollow cylindrical shell. In addition, the inventor also found that the ratio of the inner diameter to the outer diameter of the hollow cylindrical shell in the acoustic fluid sensor is a key factor affecting the degree of coupling between the local sound field and the load fluid, and also a key factor affecting the strength of the local sound field. The inventors found that the greater the ratio of the inner diameter to the outer diameter of the hollow cylindrical shell in the acoustic fluid sensor, that is, the thinner the hollow cylindrical shell, the stronger the intensity of the local sound field generated by the formation of standing waves around the hollow cylindrical shell . Tests have shown that the acoustic fluid sensor provided by the present invention has a higher quality factor and sensitivity compared to traditional acoustic fluid sensors. Especially for fluids whose density and acoustic velocity change are opposite, the acoustic fluid sensor has higher sensitivity.

In a further embodiment, the material of the hollow cylindrical shell includes polymethyl methacrylate PMMA, copper, aluminum, and steel. In other embodiments, the material of the hollow cylindrical shell further includes glass. Furthermore, the material of the hollow cylindrical shell is transparent quartz glass. The transparent quartz glass is used as the manufacturing material of the hollow cylindrical shell, which is convenient for real-time inspection and monitoring of the chemical reaction of different fluids with color changes during the experiment, and it is more flexible to carry the fluid to adapt to different application occasions.

In a further embodiment, the ratio of the inner diameter to the outer diameter of the hollow cylindrical shell is between 0.5-1. The inventors found that the thinner the hollow cylindrical shell of the acoustic fluid sensor, the stronger the intensity of the local sound field generated by forming standing waves around the hollow cylindrical shell.

In a further embodiment, the ultrasonic transmission device includes a signal generator, a power amplifier, and an ultrasonic transmission probe. The signal generator is used to generate a pulse signal, and the power amplifier is used to amplify the pulse signal to excite the ultrasonic transmitting probe to generate ultrasonic waves.

In a further embodiment, the ultrasonic receiving device includes an ultrasonic receiving probe and an analog-to-digital conversion module, the ultrasonic receiving probe is used to receive ultrasonic waves after passing through the acoustic sensing device; The ultrasonic analog quantity after passing through the acoustic sensing device is converted into an electrical signal.

In a further embodiment, the acoustic fluid sensor further includes a carrier fixing device, and the carrier fixing device is used for supporting and fixing the acoustic sensor device between the ultrasonic transmitting device and the ultrasonic receiving device. The bearing fixing device can on the one hand fix the acoustic sensing device between the ultrasonic transmitting device and the ultrasonic receiving device, on the other hand, it can also ensure that the ultrasonic wave can pass through the hollow cylindrical housing of the acoustic fluid sensor.

In a further embodiment, the bearing fixing device includes an acoustically transparent membrane, the acoustically transparent membrane is fixedly disposed under the hollow cylindrical shell, and the acoustically transparent membrane is disposed parallel to the bottom plane of the experimental container.

In a further embodiment, the environmental fluid and the load fluid are the same fluid or different fluids. For example, the environmental fluid in the experimental container may be water, and the load fluid in the hollow cylindrical shell is NaI solution; or both the NaI solution in the experimental container and the hollow cylindrical shell, or the experimental container and the hollow cylindrical shell All are water, etc. The present invention does not specifically limit this.

In a further embodiment, the quality factor of the acoustic fluid sensor is determined as follows:

Determining the angular frequency of the acoustic fluid sensor according to the intrinsic equation of the acoustic fluid sensor;

Determining the resonance frequency of the acoustic fluid sensor according to the angular frequency;

The quality factor of the acoustic fluid sensor is determined according to the resonance frequency and the bandwidth of the acoustic fluid sensor.

In the embodiment of the present invention, the eigen equation means that if the operator acts on the function equal to a constant g multiplied by the function, the equation is the eigen equation of the system, where the function is called the eigen function of the operator, g is the positive value of the operator corresponding to the eigenfunction. In determining the quality factor of the acoustic fluid sensor, the formula can be expressed as: Q = f / F, ω = 2πf; where, Q is the quality factor of the acoustic fluid sensor, f is the resonance frequency of the acoustic fluid sensor, and F is the acoustic fluid The bandwidth of the sensor, ω is the angular frequency of the acoustic fluid sensor. The angular frequency ω can be determined by the intrinsic equation of the acoustic fluid sensor.

In a further embodiment, the intrinsic equation of the acoustic fluid sensor is:

Det (D _n ) = D (n, ω) = 0;

Where n is the number of resonance modes, ω is the lowest-order solution of the eigen equation, and D _n is a square matrix with multiple rows and columns and multiple nonzero elements.

In a further embodiment, the D _n is a matrix with six rows and six columns and 28 non-zero elements as follows:

d ₁₄ = 2n [k _T2 aJ ' _n (k _T2 a) -J _n (k _T2 a);

d ₁₅ = 2n [k _T2 aY ′ _n (k _T2 a) -Y _n (k _T2 a);

d ₂₂ = k _L2 aJ ' _n (k _L2 a);

d ₂₃ = k _L2 aY ′ _n (k _L2 a);

d ₂₄ = nJ _n (k _T2 a);

d ₂₅ = nY _n (k _T2 a);

d ₃₂ = 2n [J _n (k _L2 a) -k _L2 aJ ' _n (k _L2 a)];

d ₃₃ = 2n [Y _n (k _L2 a) -k _L2 aY ′ _n (k _L2 a)];

d ₄₄ = 2n [k _T2 bJ ' _n (k _T2 b) -J _n (k _T2 b)];

d ₄₅ = 2n [k _T2 bY ′ _n (k _T2 b) -Y _n (k _T2 b)];

d ₅₂ = k _L2 bJ ' _n (k _L2 b);

d ₅₃ = k _L2 bY ′ _n (k _L2 b);

d ₅₄ = nJ _n (k _T2 b);

d ₅₅ = nY _n (k _T2 b);

d ₅₆ = -k ₃ bJ ' _n (k ₃ b);

d ₆₂ = 2n [J _n (k _L2 b) -k _L2 bJ ' _n (k _L2 b)];

d ₆₃ = 2n [Y _n (k _L2 b) -k _L2 bY ′ _n (k _L2 b)];

And meet:

k ₁ = ω / c ₁ ;

k ₃ = ω / c ₃ ;

k _L2 = ω / c _L2 ;

k _T2 = ω / c _T2 ;

Where a and b are the outer diameter and inner diameter of the hollow cylindrical shell, ρ ₁ is the density of the ambient fluid, ρ ₂ is the density of the hollow cylindrical shell, and ρ ₃ is the density of the loaded fluid , J _{n is} the Bessel function of the nth order of the eigen equation, J ′ _n is the derivative of the diagonal frequency ω of J _n ,

Is the Neumann function of the nth order of the eigen equation,

for

Derivative of diagonal frequency ω, Y _{n is} the first kind of Hankel function of the nth order of the eigen equation, Y ′ _n is the derivative of Y _n diagonal frequency ω, c ₁ is the acoustic velocity of the ambient fluid, c _L2 And c _T2 are the longitudinal and transverse wave velocities of the hollow cylindrical shell, c ₃ is the acoustic velocity of the loaded fluid, k ₁ is the wave number of the ambient fluid, and k _L2 and k _T2 are the longitudinal waves of the hollow cylindrical shell, respectively. Wave number and shear wave wave number, k ₃ is the wave number of the load fluid. All the above parameters are known parameters except the angular frequency ω. Therefore, the angular frequency ω of the acoustic fluid sensor can be determined by the above-mentioned eigen equation of the acoustic fluid sensor.

In a further embodiment, the Scholte-Stoneley circumferential wave satisfies the phase matching condition under the following conditions:

c ^p / c ₁ = Re (k ₁ a) / n;

Where c ^p is the phase velocity of the Scholte-Stoneley circumferential wave.

FIG. 2 shows a schematic structural diagram of an acoustic fluid sensor provided by an embodiment of the present invention. For ease of description, only parts related to the embodiment of the present invention are shown. Details are as follows:

As shown in FIG. 2, the acoustic fluid sensor includes a hollow cylindrical housing, a silicone tube provided at both ends of the hollow cylindrical housing and forming a through cavity therewith, and an experimental container. The ultrasonic transmitting device includes a signal generator, a power amplifier and an ultrasonic transmitting probe, the ultrasonic receiving device includes an ultrasonic receiving probe and an analog-to-digital conversion module, and the calculation processing device is a computer device. In addition, the acoustic fluid sensor further includes a sound-transmitting membrane disposed at the bottom of the hollow cylindrical housing for carrying the hollow cylindrical housing.

As shown in FIG. 2, the two ends of the hollow cylindrical shell are provided with silicone tubes, and the silicone tube and the hollow cylindrical shell form a through cavity. The two ends of the silicone tube far away from the hollow cylindrical shell are respectively connected to a syringe for injecting a load fluid (standard fluid or fluid to be measured), and a recoverer for recovering the load fluid. During the experiment, a small amount of load fluid was injected into the hollow cylindrical shell through a syringe connected to a silicone tube, and the load fluid was recovered by a reclaimer at the end of the experiment.

The experimental container is of rectangular parallelepiped type, and contains environmental fluid (such as water). In a preferred embodiment, the silicone fluid is connected to the syringe and the two ends of the collector to expose the environmental fluid during the experiment. The ultrasonic transmitting probe and the ultrasonic receiving probe are respectively installed on two opposite side walls of the experimental container. The hollow cylindrical shell is arranged between the ultrasonic generating probe and the ultrasonic receiving probe.

The signal generator generates a pulse signal, and the power amplifier amplifies the pulse signal to excite the ultrasonic transmitting probe to transmit ultrasonic waves into the environmental fluid, and excite the load fluid in the hollow cylindrical shell to form a Scholte-Stoneley circumferential wave. When the Scholte- When the Stoneley circumferential wave satisfies the phase matching condition, a standing wave is formed around the hollow cylindrical shell to generate a local sound field, an ultrasonic receiving probe receives the ultrasonic wave after passing through the acoustic sensing device, and the analog-to-digital conversion module will pass through the acoustic transmission The ultrasonic analog quantity after the sensing device is converted into an electrical signal, and the computer device converts the electrical signal from the time domain to the frequency domain, and calculates the spectrum data of the ultrasonic wave after passing through the acoustic sensing device.

The calculation processing device determines the normalized transmission spectrum data according to the first transmission spectrum data and the second transmission spectrum data, and determines the quality factor of the acoustic fluid sensor according to the normalized transmission spectrum data; wherein, the The first transmission spectrum data refers to the transmission spectrum data of the ultrasonic waves received by the ultrasonic receiving device when the acoustic sensing device and the load fluid are not included, and the second transmission spectrum data includes the acoustic sensing device and the load fluid The transmission spectrum data of the ultrasonic wave received by the ultrasonic receiving device at that time.

FIG. 3 shows a schematic diagram of the dispersion curve of the Scholte-Stoneley circumferential wave provided by an embodiment of the present invention. For ease of description, only the parts related to the embodiment of the present invention are shown. The details are as follows:

In order to illustrate the acoustic fluid sensor provided by the present invention, the larger the ratio of the inner diameter to the outer diameter of the hollow cylindrical shell, that is, the thinner the shell, the stronger the local sound field strength. The local sound field and the load fluid (standard fluid Or the fluid to be measured) the greater the coupling, the higher the quality factor of the acoustic fluid sensor, the better the sensitivity, and the more suitable it is for the properties of highly sensitive sensing of trace fluids. Embodiments of the present invention are illustrated in FIG. 3.

In the embodiment of the present invention, both the environmental fluid and the standard fluid are selected as water, the density of the environmental fluid and the density of the standard fluid are: ρ ₁ = ρ ₃ = 1000 kg / m ³ , the acoustic velocity of the environmental fluid and the sound of the standard fluid The velocities are: c ₁ = c ₃ = 1490 m / s, the density of the hollow cylindrical shell ρ ₂ = 2200 kg / m ³ , the longitudinal wave velocity of the hollow cylindrical shell is c _L2 = 3454 m / s, the transverse wave velocity of the hollow cylindrical shell It is c _T2 = 5640m / s.

In the case where other parameters remain unchanged, the acoustic fluid sensor shown in Fig. 3 is measured in three cases where the ratio of the inner diameter to the outer diameter of the hollow cylindrical shell is 3: 4, 4: 5 and 9:10 The phase velocity dispersion curve of the Scholte-Stoneley circumferential wave generated around the hollow cylindrical shell (the phase velocity divided by the sound velocity of water is normalized). It can be drawn from Figure 3 that the larger the ratio of the inner diameter to the outer diameter of the hollow cylindrical shell, that is, the thinner the shell, the smaller the phase velocity of the Scholte-Stoneley circumferential wave is than the value of the acoustic velocity of the peripheral fluid. According to the wave theory, the energy distribution of the resonance sound pressure field of the thinner cylindrical shell is more localized on the inner and outer walls of the cylindrical shell. Generally speaking, the greater the coupling between the field strength of the local sound field and the loaded fluid, the higher the quality factor of the acoustic fluid sensor and the better the sensitivity. Therefore, the thinner the hollow cylindrical shell, the quality factor of the acoustic fluid sensor The higher the sensitivity, the better, and the more suitable for highly sensitive sensing of trace fluids.

According to the wave theory, the circumferential waves whose phase velocity is less than the acoustic velocity of the environmental fluid (water) are all non-leakage waves, most of their energy can be localized on the surface of the hollow cylindrical shell, and the phase velocity is less than that of the environmental fluid (water) Acoustic velocity, the more localized their capabilities are, the more suitable they are for fluid sensing. (A)-(e) in FIG. 4 are the resonant sound pressure field distribution diagrams in FIG. 3 when the b: a is 4: 5 and the phase velocity dispersion curve has different circumferential resonance modes n = 2-6. We can see from the figure: the smaller the circumferential resonance mode n, the more localized the energy, the more suitable for fluid sensing. The following simulation experiments and actual experiments of the present invention adopt the third circumferential resonance mode.

FIG. 5a is a three-dimensional schematic view of a hollow cylindrical shell provided by an embodiment of the present invention, and FIG. 5b is a schematic plan view of a hollow cylindrical shell provided by an embodiment of the present invention.

In the embodiment of the present invention, L is the length of the hollow cylindrical shell, and a and b are the outer diameter and the inner diameter of the hollow cylindrical shell, respectively. In a preferred embodiment, the inner diameter b and the outer diameter a of the hollow cylindrical shell are b = 0.12 mm and a = 0.15 mm, respectively, and the ratio of the inner diameter b and the outer diameter a is 0.8.

An embodiment of the present invention also provides a manufacturing process of an acoustic sensing device. For ease of description, only parts related to the embodiment of the present invention are shown. The details are as follows:

The manufacturing process of the acoustic sensing device provided by the embodiment of the present invention includes at least the following steps:

Step S1: Put the A glue and the B glue in a preset ratio (for example, a ratio of 10: 1) into a vacuum deaerator and stir to mix to form a colloidal PDMS (English full name: polydimethylsiloxane, referred to as PDMS, Chinese full name: poly two Methyl siloxane). A person skilled in the art may understand that the preset ratio may also be other ratios, for example, 8: 1 or 12: 1, and the embodiment of the present invention does not specifically limit the comparison.

Step S2, smearing the gel-like PDMS on both ends of the hollow cylindrical shell, and covering the two ends of the hollow cylindrical shell with a silicone tube, the silicone tube and the hollow cylindrical shell forming a through cavity .

Step S3: Put the hollow cylindrical shells with silicone tubes at both ends into a constant temperature drying oven at a preset temperature (for example, 85 ° C.) to dry for a preset time interval (about 30 minutes). A person skilled in the art may understand that the preset temperature may also be other temperature values, such as 80 ° C or 90 ° C, and the set time interval may also be other time intervals, such as 25 minutes or 40 minutes, etc. . For example, a hollow cylindrical shell with silicone tubes at both ends is placed in a constant temperature drying oven at 80 ° C for about 40 minutes. Or put a hollow cylindrical shell with silicone tubes at both ends into a 90 ℃ constant temperature drying box for about 25 minutes and so on.

After the above steps S1 to S3, a sensing system of a hollow cylindrical shell with silicone tubes at both ends is formed. In the embodiment of the present invention, the thickness of the hollow cylindrical shell should be thin enough and the size should be small enough. In other words, the ratio of the inner diameter to the outer diameter of the hollow cylindrical shell should be large enough to make the hollow The intensity of the local sound field generated around the cylindrical shell is strong enough.

When determining the quality factor of the acoustic fluid sensor, it mainly includes the following steps:

Step 1: Without the hollow cylindrical shell and the silicone tube, turn on the ultrasonic transmitting device, the ultrasonic receiving device, and the calculation processing device.

Step 2: The signal generator in the ultrasonic transmitting device generates a pulse signal, and the power amplifier amplifies the pulse signal to excite the ultrasonic transmitting probe to generate ultrasonic waves.

Step 3: After passing the environmental fluid in the experimental container, the ultrasonic waves are received by the ultrasonic receiving probe of the ultrasonic receiving device, and the ultrasonic waves are converted into electrical signals by the analog-to-digital conversion circuit.

Step 4: Use the 5800 acquisition card to collect electrical signals. The calculation and processing device converts the electrical signals collected by the 5800 acquisition card from the time domain through the Fourier transform to the corresponding frequency domain. The first transmission spectrum data for the silicone tube.

The 5800 acquisition card is used for electrical signal acquisition, and the calculation processing device uses the MATLAB program to convert the electrical signal collected by the 5800 acquisition card from the time domain through the Fourier transform to the corresponding frequency domain, collect the effective frequency signal, and collect the collected signal Connected to a signal receiving device, the signal receiving device is preferably a computer-controlled pulse transmission receiver, and the data processing is preferably a computer to obtain the first transmission spectrum data when the hollow cylindrical shell and the silicone tube are not included. It is experimentally measured that the resonance frequency of an acoustic fluid sensor containing a hollow cylindrical shell structure at a given concentration is 2.122MHz-2.252MHz. Therefore, set the frequency of the 5800 capture card to be higher than 0.1MHz and lower than 5MHz, that is, only the frequency higher than 0.1MHz and lower than 5MHz is allowed to pass. Therefore, the signal transmitted by the ultrasonic transmitting probe and the signal received by the ultrasonic receiving probe are within this frequency range.

Step 5: Install the ultrasonic generating probe, the ultrasonic receiving probe and the sound-transmitting membrane on the fixing bracket, and the sound-transmitting membrane is used to carry and fix the hollow cylindrical housing between the ultrasound transmitting probe and the ultrasound receiving probe . And the acoustic sensing device made of steps S1 to S3 including a hollow cylindrical shell and a silicone tube is placed in the middle of the ultrasonic generating probe and the ultrasonic receiving probe, so as to ensure that most of the energy of the ultrasonic wave emitted by the ultrasonic generating probe can After passing through the sensing system of the hollow cylindrical shell, most of the ultrasonic waves are finally received by the ultrasonic receiving device.

Step 6: Immerse the assembled ultrasonic generating probe, hollow cylindrical shell, and ultrasonic receiver in an experimental container filled with environmental fluid. During the experiment, standard fluid is injected into the hollow cylindrical shell through a syringe through a silicone tube.

6a-6d are schematic diagrams showing the relationship between the concentration, density, and sound velocity of the four standard fluids of sample 1, sample 2, sample 3, and NaI solution provided by an embodiment of the present invention. For ease of explanation, only the implementation of the present invention is shown. The relevant parts of the example are detailed as follows:

In the embodiment of the present invention, it has been found through experiments (see FIG. 7 and the corresponding embodiment part of FIG. 7 and described in detail below) that the acoustic fluid sensor system is most sensitive to the density change of the fluid, so the environmental fluid is determined as water The fluids were set as Sample 1, Sample 2, Sample 3, and NaI solution.

Among them, Figure 6a shows the fluid density and fluid sound velocity of sample 1 with the concentration (select the density and sound velocity data at 6%, 30%, 40% and 45% concentration, and perform the density and sound velocity data Fit to get the change curve of solution concentration, density and acoustic velocity); Figure 6b shows the fluid density and fluid acoustic velocity of sample 2 with concentration (selected concentrations are 6%, 30%, 40% and 45% concentration) Density and sound velocity data under the following conditions, and the density and sound velocity data are fitted to obtain the solution concentration, density and sound velocity relationship) change curve; Figure 6c shows the fluid density of sample 3, fluid sound velocity with concentration (Choose density and sound velocity data at concentrations of 6%, 30%, 40% and 45%, and fit the density and sound velocity data to obtain the relationship between solution concentration, density and sound velocity); Fig. 6d shows the fluid density and fluid sound velocity of NaI solution with the concentration (select the density and sound velocity data at concentrations of 6%, 30%, 40% and 45%, and fit the density and sound velocity data To get the solution concentration and density Degree and sound velocity relationship).

Step 7. In the case of including the hollow cylindrical shell and the silicone tube, turn on the ultrasonic transmitting device, the ultrasonic receiving device, and the calculation processing device.

Step 8. The signal generator in the ultrasonic transmitting device generates a pulse signal, and the power amplifier amplifies the pulse signal to excite the ultrasonic transmitting probe to generate ultrasonic waves.

Step 9: After passing through the hollow cylindrical shell, the ultrasonic waves are received by the ultrasonic receiving probe, and the ultrasonic waves are converted into electrical signals by the analog-to-digital conversion circuit.

Step 10: Use the 5800 acquisition card to collect electrical signals. The computer device converts the electrical signals collected by the 5800 acquisition card from the time domain to the corresponding frequency domain through Fourier transform, and acquires the hollow cylindrical shell and the silicone tube. The second transmission spectrum data at the time.

Step 11: The computer device normalizes the first transmission spectrum data and the second transmission spectrum data to obtain the normalized transmission spectrum data, and determines the quality of the acoustic fluid sensor according to the normalized transmission spectrum data factor.

In determining the quality factor of the acoustic fluid sensor, the formula can be expressed as: Q = f / F, ω = 2πf; where, Q is the quality factor of the acoustic fluid sensor, f is the resonance frequency of the acoustic fluid sensor, and F is the acoustic fluid The bandwidth of the sensor, ω is the angular frequency of the acoustic fluid sensor. The angular frequency ω can be determined by the intrinsic equation of the acoustic fluid sensor.

When determining the quality factor of the acoustic fluid sensor, the load fluid is a standard fluid with known parameters, and the standard fluid is used to determine the relationship between the resonance frequency and the fluid density or fluid concentration. After using the standard fluid with known parameters to determine the relationship between the resonance frequency and the fluid density or fluid concentration, replace the standard in the hollow cylindrical shell with the fluid to be measured (where the parameters of the fluid to be measured, such as fluid density and fluid acoustic velocity are unknown) Fluid, that is, the fluid to be tested is injected into the hollow cylindrical shell from the syringe through the silicone tube during the experiment, and repeating steps 5 to 10, the parameters of the fluid to be measured (such as the fluid density or Fluid sound velocity, etc.).

The invention has been verified by simulation experiments and actual experiments, and is in line with the expected results, and proved feasible.

FIG. 7 is a schematic diagram showing the relationship between the solution concentration and resonance frequency of four different standard fluids provided by an embodiment of the present invention. For ease of explanation, only relevant parts of the embodiment of the present invention are shown. Details are as follows:

In the embodiment of the present invention, four standard fluids of sample 1, sample 2, sample 3, and NaI solution are selected for simulation experiment verification. According to the above steps 5 to 10, the simulation experiments of sample 1, sample 2, sample 3 and NaI solution at different solution concentrations (selected 6%, 30%, 40% and 45% respectively in the embodiment of the present invention) were determined respectively Resonance frequency at the time of verification.

In the embodiment of the present invention, simulation experiment verification is mainly performed on COMSOL Multiphysics software (COMSOL Multiphysics is multiphysics simulation analysis software). In the specific simulation experiment, first simulate the local field strength of the system without the hollow cylindrical shell and the silicone tube to obtain a set of transmission spectrum data; then simulate the hollow cylindrical shell and the silicone tube (that is, the acoustic sensing device) The local field strength of the acoustic sensor system is obtained a set of transmission spectrum data; and then the two sets of transmission spectrum data are normalized to obtain the normalized transmission spectrum data, that is, the normalized transmission spectrum chart. Using the above-mentioned methods, COMSOL Multiphysics simulation software was used to simulate the resonant frequency shift curves of samples 1, 2, 3 and NaI solutions at concentrations of 6%, 30%, 40% and 45% respectively. The results are as follows As shown in Figure 7.

Among them, sample 1 is a hypothetical fluid, the density of the hypothetical fluid is 1046.3kg / m ³ , and it remains unchanged during the simulation experiment. / s, 1509m / s and 1524m / s resonance frequency shift curve of the acoustic fluid sensor. Sample 2 is a hypothetical fluid. The acoustic velocity of the hypothetical fluid is 1483 m / s, and it remains unchanged during the simulation experiment. Figure 7 shows that the density of the hypothetical fluid increases from 1046.3 kg / m ³ to 1290.7 kg. / m ³ , 1427.1 kg / m ³ , and 1506.2 kg / m ³ at the resonance frequency shift curve of the acoustic fluid sensor. Sample 3 is a hypothetical fluid. Figure 7 shows that the density of the hypothetical fluid increases from 1046.3kg / m ³ to 1290.7kg / m ³ , 1427.1kg / m ³ , 1506.2kg / m ³ , and the sound velocity from 1524m / s The resonance frequency shift curves of the acoustic fluid sensor when the changes are 1494m / s, 1486.5m / s and 1483m / s. Fig. 7 also shows the resonance frequency shift curve of the acoustic fluid sensor at concentrations of 6%, 30%, 40% and 45% of the NaI solution.

From the graph of the resonance frequency shift curve of the acoustic fluid sensor of sample 1 shown in FIG. 7, it can be known that the resonance frequency of the acoustic fluid sensor remains basically unchanged when the fluid density remains unchanged and the acoustic velocity changes significantly It can be known from the resonance frequency shift curve of the acoustic fluid sensor of sample 2 and sample 3 shown in FIG. 7 that no matter whether the acoustic velocity of the fluid changes significantly, in the case where the density of the fluid changes significantly, the acoustic fluid The resonant frequency of the sensor has changed significantly, indicating that the acoustic fluid sensor is sensitive to changes in fluid density.

FIG. 8 is a schematic diagram of the resonance frequency and transmission amplitude of the NaI solution simulated and calculated at different solution concentrations provided by the embodiment of the present invention. For ease of description, only the parts related to the embodiment of the present invention are shown. The details are as follows:

As shown in FIG. 8, it is the transmission spectrum diagram of the acoustic fluid sensor obtained by the simulation calculation of the NaI solution at the concentrations of 6%, 30%, 40%, and 45%, respectively. It can be seen from the figure that the resonance frequency of the acoustic fluid sensor verified by the simulation experiment is between 2.12MHz-2.25MHz. Through the analysis and calculation of the transmission spectrum shown in FIG. 8, the quality factor of the acoustic fluid sensor verified by the simulation experiment is about 126; at the same time, the acoustic verification of the simulation experiment can also be obtained by the transmission spectrum shown in FIG. 8. The maximum offset value of the resonance frequency of the fluid sensor (that is, the sensitivity is the difference between the maximum resonance frequency and the minimum resonance frequency shown in Figure 8) is about 0.13MHz (that is, the difference between the maximum resonance frequency 2.25MHz and the minimum resonance frequency 2.12MHz) ). Compared with the traditional acoustic fluid sensor, this new type of acoustic fluid sensor with a hollow cylindrical housing not only has a high quality factor, but also has a high sensitivity, thus verifying the feasibility of theoretical simulation.

FIG. 9 is a schematic diagram of the resonance frequency and transmission amplitude of the NaI solution provided by the embodiment of the present invention at different solution concentrations in actual experiments. For ease of explanation, only the relevant parts of the embodiment of the present invention are shown. The details are as follows:

As shown in FIG. 9, they are transmission spectrum diagrams of acoustic fluid sensors obtained by actual experiments of NaI solutions at concentrations of 6%, 30%, 40%, and 45%, respectively. It can be seen from the figure that the resonance frequency of the acoustic fluid sensor in the actual experiment is between 2.10MHz-2.24MHz, which is basically consistent with the resonance frequency of the acoustic fluid sensor calculated by simulation is 2.12MHz-2.25MHz. In addition, the transmission amplitude of the transmission spectrum of the acoustic fluid sensor obtained in the actual experiment is attenuated compared to the transmission amplitude of the transmission spectrum of the acoustic fluid sensor obtained by the simulation calculation, because the theoretical calculation is based on the ideal environment, and the actual experiment has acoustic scattering Or the amplitude attenuation caused by absorption, etc., is also in line with common sense, thus verifying the feasibility of the experiment.

The acoustic fluid sensor provided by the embodiment of the present invention has the following advantages:

(1) The acoustic fluid sensor with high sensitivity and high quality factor proposed by the present invention is a novel acoustic fluid sensor with a hollow cylindrical housing structure. The acoustic fluid sensor not only has the advantages of miniature size and local strong field; at the same time, the size of the hollow cylindrical shell is variable, and when the system size becomes larger or smaller, the properties of the system will not change, only the operating frequency will be Proportional shift to meet the resonance frequency of different sections. In addition, the size design of the hollow cylindrical shell structure is a key condition for the phase matching of the resonance of the circumferential wave around the hollow cylindrical shell.

(2) A new type of acoustic fluid sensor with a hollow cylindrical shell structure proposed by the present invention is not only sensitive to fluids with significant density changes, but also can detect fluids with the same or opposite trends in density and sound velocity. As well as detecting a fluid whose density is constant and changing only the sound velocity, or a fluid whose sound velocity is constant and changing only the density, etc.

(3) The high-sensitivity and high-quality factor acoustic fluid sensor proposed by the present invention, the fluid to be measured may be a trace amount, only filled in a hollow cylindrical shell, and the environmental fluid may include common fluids such as water, and may also be in and around the cylindrical shell The environment is filled with the fluid to be measured.

(4) The new acoustic fluid sensor based on the hollow cylindrical shell structure with high sensitivity and high quality factor proposed by the present invention can generate a local strong field to enhance the interaction between the acoustic wave and the substance, thereby improving the detection sensitivity and the acoustic fluid sensor The ability to respond quickly.

(5) The novel acoustic fluid sensor including a hollow cylindrical shell structure proposed by the present invention not only has a higher resonance frequency shift (ie sensitivity), but also has a high quality factor.

(6) The new acoustic fluid sensor based on the hollow cylindrical shell structure with high sensitivity and high quality factor proposed by the present invention may be suitable for diagnosis, biochemical detection, clinical medical diagnosis, environmental monitoring, and food safety monitoring in biomedical engineering in the future And industrial measurement.

(7) The novel acoustic fluid sensor provided with a hollow cylindrical shell structure proposed by the present invention has high stability, compact structure, simple process, low cost, and is easy for large-scale industrial production. In addition, the invention can use the quartz glass of the transparent pipe as the material of the hollow cylindrical shell, which is convenient for real-time monitoring of the chemical reactions of different fluids with color changes, and can carry fluids more flexibly to adapt to different application occasions.

(8) The acoustic fluid sensor provided with a hollow cylindrical shell structure proposed by the present invention not only has high sensitivity, that is, high frequency offset, but also has a high quality factor. The acoustic fluid sensor based on the hollow cylindrical shell structure with high sensitivity and high quality factor is an important direction for future research.

(9) The acoustic fluid sensor provided with a hollow cylindrical shell structure proposed by the present invention is an acoustic fluid sensor that is relatively sensitive to fluids with significant density changes. At the same time, the system can detect the fluid's density, elastic modulus, sound velocity, viscosity and other properties, and use these parameters to further infer the fluid's composition, concentration and other derived properties.

In summary, the acoustic fluid sensor in the embodiment of the present invention includes an acoustic sensing device, an experimental container, an ultrasonic transmitting device, an ultrasonic receiving device, and a calculation processing device; the acoustic sensing device includes a hollow cylindrical shell for containing a load fluid Body, and a silicone tube provided at both ends of the hollow cylindrical shell and forming a through cavity therewith. In the embodiment of the present invention, an ultrasonic wave transmitting device is used to transmit ultrasonic waves to the environmental fluid to excite the load fluid in the hollow cylindrical shell to form a Scholte-Stoneley circumferential wave. When the Scholte-Stoneley circumferential wave meets the phase matching condition, A local sound field is generated around the standing wave, and the local sound field generated at this time has a greater degree of coupling with the load fluid. Therefore, the quality factor and sensitivity of the acoustic fluid sensor can be improved, which is suitable for highly sensitive sensing of trace fluids.

Those skilled in the art should understand that the embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer usable program code.

The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each flow and / or block in the flowchart and / or block diagram and a combination of the flow and / or block in the flowchart and / or block diagram may be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, special-purpose computer, embedded processing machine, or other programmable data processing device to produce a machine that enables the generation of instructions executed by the processor of the computer or other programmable data processing device A device for realizing the functions specified in one block or multiple blocks of one flow or multiple blocks of a flowchart.

These computer program instructions may also be stored in a computer readable memory that can guide a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture including an instruction device, the instructions The device implements the functions specified in one block or multiple blocks of the flowchart one flow or multiple flows and / or block diagrams.

These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operating steps are performed on the computer or other programmable device to produce computer-implemented processing, which is executed on the computer or other programmable device The instructions provide steps for implementing the functions specified in one block or multiple blocks of the flowchart one flow or multiple flows and / or block diagrams.

The specific embodiments described above further describe the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the scope of the present invention. The scope of protection, within the spirit and principle of the present invention, any modification, equivalent replacement, improvement, etc., should be included in the scope of protection of the present invention.

Claims (12)

1. An acoustic fluid sensor, characterized in that it includes:

   Acoustic sensing device, experimental container, ultrasonic transmitting device, ultrasonic receiving device and computing processing device;

   The acoustic sensing device includes a hollow cylindrical shell for containing a load fluid, and a silicone tube provided at both ends of the hollow cylindrical shell and forming a through cavity therewith;

   The experimental container is used to contain environmental fluid, the hollow cylindrical shell is immersed in the environmental fluid, and the acoustic sensing device is disposed between the ultrasonic transmitting device and the ultrasonic receiving device;

   The ultrasonic wave emitting device emits ultrasonic waves into the environmental fluid to excite the load fluid in the hollow cylindrical shell to form a Scholte-Stoneley circumferential wave. When the Scholte-Stoneley circumferential wave satisfies the phase matching condition, the hollow A standing wave is formed around the cylindrical shell to generate a local sound field, and the ultrasonic receiving device receives ultrasonic waves after passing through the acoustic sensing device;

   The calculation processing device determines the normalized transmission spectrum data according to the first transmission spectrum data and the second transmission spectrum data, and determines the quality factor of the acoustic fluid sensor according to the normalized transmission spectrum data; wherein, the The first transmission spectrum data refers to the transmission spectrum data of the ultrasonic waves received by the ultrasonic receiving device when the acoustic sensing device and the load fluid are not included, and the second transmission spectrum data includes the acoustic sensing device and the load fluid The transmission spectrum data of the ultrasonic wave received by the ultrasonic receiving device at that time.
2. The acoustic fluid sensor according to claim 1, wherein the material of the hollow cylindrical housing is polymethyl methacrylate PMMA, copper, aluminum and steel.
3. The acoustic fluid sensor according to claim 1, wherein the ratio of the inner diameter to the outer diameter of the hollow cylindrical housing is between 0.5-1.
4. The acoustic fluid sensor according to claim 1, wherein the ultrasonic transmitting device comprises:

   Signal generator, power amplifier and ultrasonic transmitting probe;

   The signal generator is used to generate a pulse signal, and the power amplifier is used to amplify the pulse signal to excite the ultrasonic transmitting probe to generate ultrasonic waves.
5. The acoustic fluid sensor according to claim 1, wherein the ultrasonic receiving device comprises:

   Ultrasonic receiving probe and analog-to-digital conversion module;

   The ultrasonic receiving probe is used to receive ultrasonic waves after passing through the acoustic sensing device;

   The analog-to-digital conversion module is used to convert the ultrasonic analog after passing through the acoustic sensing device into an electrical signal.
6. The acoustic fluid sensor according to claim 1, further comprising:

   A load-bearing fixing device, which is used to load-bearing and fix the acoustic sensing device between the ultrasonic transmitting device and the ultrasonic receiving device.
7. The acoustic fluid sensor according to claim 6, wherein the bearing fixing device is an acoustically transparent membrane.
8. The acoustic fluid sensor according to claim 1, wherein the environmental fluid and the load fluid are the same fluid or different fluids.
9. The acoustic fluid sensor according to claim 1, wherein the quality factor of the acoustic fluid sensor is determined as follows:

   Determining the angular frequency of the acoustic fluid sensor according to the intrinsic equation of the acoustic fluid sensor;

   Determining the resonance frequency of the acoustic fluid sensor according to the angular frequency;

   The quality factor of the acoustic fluid sensor is determined according to the resonance frequency and the bandwidth of the acoustic fluid sensor.
10. The acoustic fluid sensor according to claim 9, wherein the intrinsic equation of the acoustic fluid sensor is:

    Det (D _n ) = D (n, ω) = 0;

    Where n is the number of resonance modes, ω is the lowest-order solution of the eigen equation, and D _n is a square matrix with multiple rows and columns and multiple non-zero elements.
11. The acoustic fluid sensor according to claim 10, wherein D _n is a matrix with six rows and six columns and 28 non-zero elements as follows:

    

    

    

    d ₁₄ = 2n [k _T2 aJ ' _n (k _T2 a) -J _n (k _T2 a);

    d ₁₅ = 2n [k _T2 aY ′ _n (k _T2 a) -Y _n (k _T2 a);

    

    d ₂₂ = k _L2 aJ ' _n (k _L2 a);

    d ₂₃ = k _L2 aY ′ _n (k _L2 a);

    d ₂₄ = nJ _n (k _T2 a);

    d ₂₅ = nY _n (k _T2 a);

    d ₃₂ = 2n [J _n (k _L2 a) -k _L2 aJ ' _n (k _L2 a)];

    d ₃₃ = 2n [Y _n (k _L2 a) -k _L2 aY ′ _n (k _L2 a)];

    

    

    

    

    d ₄₄ = 2n [k _T2 bJ ' _n (k _T2 b) -J _n (k _T2 b)];

    d ₄₅ = 2n [k _T2 bY ′ _n (k _T2 b) -Y _n (k _T2 b)];

    

    d ₅₂ = k _L2 bJ ' _n (k _L2 b);

    d ₅₃ = k _L2 bY ′ _n (k _L2 b);

    d ₅₄ = nJ _n (k _T2 b);

    d ₅₅ = nY _n (k _T2 b);

    d ₅₆ = -k ₃ bJ ' _n (k ₃ b);

    d ₆₂ = 2n [J _n (k _L2 b) -k _L2 bJ ' _n (k _L2 b)];

    d ₆₃ = 2n [Y _n (k _L2 b) -k _L2 bY ′ _n (k _L2 b)];

    

    

    And meet:

    k ₁ = ω / c ₁ ;

    k ₃ = ω / c ₃ ;

    k _L2 = ω / c _L2 ;

    k _T2 = ω / c _T2 ;

    Where a and b are the outer diameter and inner diameter of the hollow cylindrical shell, ρ ₁ is the density of the ambient fluid, ρ ₂ is the density of the hollow cylindrical shell, and ρ ₃ is the density of the loaded fluid , J _{n is} the Bessel function of the nth order of the eigen equation, J ′ _n is the derivative of the diagonal frequency ω of J _n ,

    

    Is the Neumann function of the nth order of the eigen equation,

    

    for

    

    Derivative of diagonal frequency ω, Y _{n is} the first kind of Hankel function of the nth order of the eigen equation, Y ′ _n is the derivative of Y _n diagonal frequency ω, c ₁ is the acoustic velocity of the ambient fluid, c _L2 And c _T2 are the longitudinal and transverse wave velocities of the hollow cylindrical shell, c ₃ is the acoustic velocity of the loaded fluid, k ₁ is the wave number of the ambient fluid, and k _L2 and k _T2 are the longitudinal waves of the hollow cylindrical shell, respectively. Wave number and shear wave wave number, k ₃ is the wave number of the load fluid.
12. The acoustic fluid sensor according to claim 11, wherein the Scholte-Stoneley circumferential wave satisfies the phase matching condition under the following conditions:

    c ^p / c ₁ = Re (k ₁ a) / n;

    Where c ^p is the phase velocity of the Scholte-Stoneley circumferential wave.

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