A method for measuring the electromechanical coupling coefficient and equivalent model parameters of a blood viscoelasticity sensor

Abstract

The application discloses a blood viscoelasticity sensor electromechanical coupling coefficient and equivalent model parameter measurement method, belongs to the field of blood coagulation analysis, and establishes a mechanical vibration system equivalent model of a blood viscoelasticity sensor and an equivalent circuit of a coil in the sensor, deduces a formula of the coil dynamic impedance module, loads loads with different masses on a sensor probe, calculates M m_n1 、 K m_n1 、 R m_n1 、 M m_n2 、 K m_n2 and R m_n2 ; so that the electromechanical coupling coefficient and the equivalent model parameters of the sensor vibration system are calculated M m 、 K m and R m ; the above measurement steps do not need to disassemble the viscoelasticity sensor from the system, do not depend on specific tooling, and are simple to operate.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of coagulation analysis, in particular to a method for measuring the electromechanical coupling coefficient and equivalent model parameters of a blood viscoelasticity sensor. BACKGROUND

[0002] During the blood coagulation process, fibrin, platelets and blood cells form a three-dimensional cross-linked network structure, and under the action of fibrinolysin, fibrin is dissolved. During this process, the blood viscoelasticity changes. By detecting the changes in blood viscoelasticity during coagulation through a detection device, the coagulation process can be qualitatively or quantitatively analyzed, which can help doctors understand the coagulation function information of patients and make accurate diagnosis and treatment.

[0003] CN201921454553.9 discloses a thrombelastography sensor, the structure of which is shown in Figure 1 , mainly comprising a magnetic cap 1, a permanent magnet 2, a coil 3, a probe seat 4, a vibrating spring 5, a bottom plate 6 and a probe head 7. The permanent magnet 2 is fixed in the accommodating hole at the top of the magnetic cap 1, and a stable and constant magnetic field is formed in the air gap between the permanent magnet 2 and the magnetic cap 1. The probe seat 4 is movably sleeved on the bottom of the permanent magnet 2 at the top, the coil 3 is single-directionally wound in the annular groove at the top of the probe seat 4, and the coil 3 is in the stable and constant magnetic field. The joint of the coil 3 is led out. In operation, the coil 3 is connected with alternating current, the coil 3 is subjected to alternating force in the stable and constant magnetic field, and vibrates along the central symmetry axis direction, driving the probe seat 4 to move synchronously. The vibrating spring 5 fixed with the probe seat 4 provides a restoring force for vibration, the probe head 7 is fixed on the probe seat 4, and the lower end of the probe head 7 is inserted into the measured blood. The mechanical properties of the measured blood will affect the movement state of the sensor moving part.

[0004] The above blood viscoelasticity sensor constitutes an electromechanical coupling system, and the electromechanical coupling is realized through Lorentz force and Faraday electromagnetic induction effect. The electromechanical coupling coefficient of the system is determined by the sensor magnetic circuit and the geometric parameters of the coil, and is a key system parameter of the sensor, which determines the driving force and response signal of the sensor. CN202310893884.7 discloses a measuring method for measuring the spatial distribution of the electromechanical coupling coefficient of such a blood viscoelasticity sensor. Although this method can accurately determine the spatial distribution of the electromechanical coupling coefficient of the sensor at the axial position, it needs to use a displacement measuring device and an impedance analysis circuit, and needs to disassemble the sensor from the application system and install it in a specific detection tool for measurement. For application scenarios that only need to know the electromechanical coupling coefficient at the axial position of the current sensor coil, this method is relatively cumbersome. SUMMARY

[0005] To overcome the shortcomings of the prior art, one of the purposes of the present application is to provide a method for measuring the electromechanical coupling coefficient and equivalent model parameters of a blood viscoelasticity sensor without disassembling the sensor from the application system.

[0006] One of the purposes of the present application is achieved by adopting the following technical solutions:

[0007] A method for measuring the electromechanical coupling coefficient and equivalent model parameters of a blood viscoelasticity sensor, comprising the following steps:

[0008] S1: Establishing an equivalent model of the mechanical vibration system of the blood viscoelasticity sensor, the model parameters including the equivalent mass block mass M m , spring elastic coefficient K m , damper damping coefficient R m and electromechanical coupling coefficient ;

[0009] S2: Establishing an equivalent circuit of the sensor coil, according to the equivalent circuit, the motional impedance of the coil , wherein is the angular frequency, is a pure imaginary number; the modulus of , normalizing , and relative to the constant , let ; substituting the normalized and into the expression of , to obtain

[0010] S3: Loading a load with a mass of M m1 on the sensor probe, measuring the motional impedance amplitude m1 (j Z ) of the sensor coil corresponding to at least three different angular frequencies ω , and bringing at least three and the corresponding Z m1 (j ω ) data into the formula , to calculate M m_n1 , K m_n1 and R m_n1 ;

[0011] S4: Loading a load with a mass of M m2 on the sensor probe, M m2 not equal to Mm1 At least three different angular frequencies of the sensor coil were measured. The corresponding motional impedance amplitude | Z m2 (j ω The data will include at least three... And the corresponding | Z m2 (j ω Substitute data into the formula Calculate M m_n2 , K m_n2 and R m_n2 ;

[0012] S5: Will M m1 , M m2 , M m_n1 as well as M m_n2 Substitution The electromechanical coupling coefficient was calculated. ;

[0013] S6: Will M m_n =M m_n1 、K m_n= K m_n1 、R m_n =R m_n1 as well as Bl Substitution , The equivalent model parameters of the sensor vibration system were calculated. M m , K m and R m .

[0014] Further, in step S1, based on the equivalent model of the mechanical vibration system, under time-harmonic conditions, the probe motion equation based on phasor representation is: In the formula, V p The phasor represents the velocity of the probe. F m The phasor of the driving force on the probe is provided by the Lorentz force on the coil. In the formula, I cis the phasor of the current in the coil; K is the electromechanical coupling coefficient is defined by the following equation: wherein, is a conductor vector line element of the coil, is the magnetic flux density vector, denotes the closed loop geometry of the coil, the coefficient determines the driving force of the sensor and the induced electromotive force in the coil, i.e. the electromechanical coupling coefficient of the electromechanical coupling system formed by the sensor.

[0015] Further, in step S2, the coil equivalent impedance is wherein, is the coil terminal voltage, is the current in the coil, is the DC resistance of the coil, is the coil inductance, the term is the motional impedance of the coil.

[0016] Further, in steps S3 and S4, the corresponding impedance amplitude is calculated from a plurality of motional M m_n , K m_n and R m_n then any one of the least square identification method, the gradient correction identification method or the probability density approximation identification method is used.

[0017] Further, in steps S3 and S4, M m1 is 0, i.e. there is no additional mass load on the sensor probe; M m2 is a mass block with a mass of M m2 in step S4, the mass block M m2 is rigidly connected to the probe of the sensor for motional impedance amplitude measurement of the sensor coil.

[0018] Further, in step S4, repeated experiments are also performed using a plurality of mass blocks with different masses to obtain the relationship between and , the coefficient is obtained by linear fitting method, and is in a linear relationship, and the slope of the straight line is .

[0019] Further, in steps S3 and S4, the load mass changes the balance position of the coil, in order to ensure that the coefficient Invariable, the balance position difference of the coil is less than or equal to 10 mu m.

[0020] Further, in step S1, the mass of the equivalent mass block is Wherein, The additional radiation mass when the two spring radiation sound fields of the vibration viscoelastic sensor are represented; the sum of the probe itself mass and the equivalent mass of the spring is represented.

[0021] Compared with the prior art, the blood viscoelastic sensor electromechanical coupling coefficient and equivalent model parameter measurement method of the application establishes the equivalent model of the mechanical vibration system of the blood viscoelastic sensor and the equivalent circuit of the coil in the sensor, derives the formula of the dynamic impedance module of the coil, calculates the M m_n1 , K m_n1 , R m_n1 , M m_n2 , K m_n2 And R m_n2 ; so as to calculate the coefficient Bl And the equivalent model parameters of the sensor vibration system M m , K m And R m ; through the above steps, the viscoelastic sensor does not need to be taken out of the system, does not depend on specific tooling, and is simple to operate. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is a perspective view of the existing thrombus elasticity detection sensor in the background art;

[0023] Figure 2 It is a flow chart of the blood viscoelastic sensor electromechanical coupling coefficient and equivalent model parameter measurement method of the application;

[0024] Figure 3 It is a schematic diagram of the equivalent model of the mechanical vibration system of the viscoelastic sensor in the application;

[0025] Figure 4 It is an equivalent circuit diagram of the coil of the viscoelastic sensor in the application;

[0026] Figure 5 It is the dynamic impedance amplitude-frequency characteristic diagram of the coil of the viscoelastic sensor in the application;

[0027] Figure 6 ​This is a phase frequency characteristic diagram of the motional impedance of the viscoelastic sensor coil in this invention;

[0028] Figure 7 The spectrum of motional impedance amplitudes for the six mass loads in a single measurement;

[0029] Figure 8 The graph shows the linear fit between the normalized mass and the added mass for the six mass loads in a single measurement.

[0030] Figure 9 Normalized quality plots for each load when the experiment is repeated 10 times;

[0031] Figure 10 The coefficients corresponding to the mass differences of the 5 groups when each load is repeated 10 times. Bl ;

[0032] Figure 11 Linear fit plot of normalized mass versus added mass when each load is repeated 10 times. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0035] Figure 2 This is a flowchart of the method for measuring the electromechanical coupling coefficient and equivalent model parameters of the blood viscoelastic sensor according to the present invention. Specifically, the method for measuring the electromechanical coupling coefficient and equivalent model parameters of the blood viscoelastic sensor according to the present invention is as follows:

[0036] 1.1 Equivalent Model of Mechanical Vibration System

[0037] Figure 1 The motion of the sensor probe shown is used Figure 3 The figure shows a single-degree-of-freedom, second-order damped equivalent model. The probe moves along... z Axial vibration, where the spring constant... K mKtotai R m Ktotai M m Ktotai M m Ktotai

[0038] ;

[0039] Ktotai M r Ktotai Ktotai

[0040] In the case of a time-harmonic motion, the equation of motion of the probe in phasor representation is

[0041] ;

[0042] Ktotai ω is the angular frequency, j is the imaginary unit, V p is the phasor of the probe velocity; F m is the phasor of the driving force experienced by the probe, provided by the Lorentz force experienced by the coil, i.e. by the following expression

[0043] ;

[0044] Ktotai I c is the phasor of the current in the coil; the coefficient is defined by the following expression

[0045] (4)

[0046] Ktotai is a vector line element of a segment of the coil; is the magnetic flux density vector; Ktotai determines the driving force of the sensor and the induced electromotive force in the coil, i.e. the electromechanical coupling coefficient of the electromechanical coupling system constituted by the sensor.

[0047] 1.2 The motional impedance of the coil

[0048] When a time-harmonic current flows through the coil of a vibratory viscoelastic sensor, the resulting harmonic Lorentz force drives the coil, producing harmonic motion, which in turn causes the sensor's probe to move synchronously. The probe interacts with the sample being measured, and its motion is influenced by the mechanical properties of the sample. Since the coil and probe are rigidly connected, their velocity phasor in the magnetic field is also... V p Then the phasor of the induced electromotive force in the coil can be obtained. U m for

[0049] ;

[0050] Changes in the induced electromotive force will lead to changes in the equivalent impedance of the coil. In summary, changes in the mechanical properties of the sample will modulate the equivalent impedance of the coil.

[0051] Since the sensor operates at a low frequency, the eddy current losses in the coil can be ignored. When considering the equivalent circuit of the coil, the equivalent resistance representing the eddy current losses in the high-frequency region can be neglected; only the DC resistance of the coil wire needs to be considered. Coil inductance and style (5) The motional electromotive force represented The influence of small signals. Under the action of small signals, the sensor can be regarded as a lumped parameter linear system, so the equivalent circuit of the coil can be used. Figure 4 express. Figure 4 In, equivalent circuit elements and The values ​​are respectively

[0052] ;

[0053] Figure 4 middle, The component of the coil's equivalent impedance affected by the induced electromotive force is called motional impedance. The expression is as follows

[0054] ;

[0055] In the formula, the third term on the right is the motional impedance of the coil. ,

[0056] ;

[0057] The modulus and phase angle are respectively

[0058] ;

[0059] Their frequency characteristics are shown in Figure 5 as well asFigure 6 . The phase is zero at the angular frequency and its modulus takes a maximum value . The expression for

[0060] .

[0061] 1.3 Dynamic viscoelasticity and equivalent load mass detection method based on dynamic impedance model parameter identification

[0062] Let and be normalized relative constants, let

[0063] ;

[0064] Substitute the above three equations into equation (11), then can be rewritten as

[0065] ;

[0066] From equation (17), it can be seen that the frequency spectrum of is uniquely determined by a specific set of model parameters and . In an ideal case, if the values of at three different angular frequencies are known, substituting equation (17) gives three equations, and solving this system of equations gives the uniquely determined model parameters and . However, the measured inevitably contains various errors, and it is difficult to ensure the accuracy of the model parameters determined from limited three-point data. In order to reduce the influence of random errors in the measurement data, it is necessary to establish a model parameter estimation result with better statistical performance on the basis of a large amount of measurement data. The number of linearly independent equations obtained in this way is much larger than the number of undetermined model parameters, i.e., it is an "overdetermined problem". By using the frequency spectrum data of ω in a certain interval, an overdetermined equation system is established, and the model parameters are identified, so that more accurate model parameters , and can be obtained.

[0067] ​​The model structure of motional impedance is known, and the identification of its model parameters falls under the category of parametric model identification problems in modern identification methods. This parametric model identification problem is solved by minimizing the error criterion function between the model and the measured data. Modern identification methods, in terms of their basic principles, can be divided into three types: least squares identification methods, gradient correction identification methods, and probability density approximation identification methods. The least squares method, among the least squares identification methods, is the most fundamental, its related theory is well-developed, and its application is the most widespread. The least squares method is adopted here.

[0068] Assuming the equivalent mass of the sensor vibration system changed in both experiments, the amplitude spectrum of the motional impedance of the coil before and after the change in equivalent mass was measured, and the equation was used... The model function of (17) can identify the corresponding experimental results between the two experiments. The values ​​are denoted as follows: and Utilization (16) The following formula holds true.

[0069] ;

[0070] In the formula, , which is the difference in the equivalent mass of the vibration system in the two experiments. If the mass difference... If the value is known, then the coefficient It is easy to obtain.

[0071] In theory, it can also be controlled or The coefficient is obtained by similar method from the difference. However, compared to other methods, controlling poor quality is simpler and easier to implement.

[0072] From the perspective of improving the signal-to-noise ratio, the voice coil displacement amplitude during impedance spectrum measurement should be as large as possible, but both are subject to certain limitations. The above analysis implicitly assumes that the coefficient of the voice coil's position changes before and after the load mass change. They should be equal. However, the load mass changes the balance position of the voice coil, which may cause the coefficient to... The difference. Fortunately, the sensor design ensures the coefficient... It possesses a certain spatial constant region. During sensor use, the magnetic circuit structure remains constant, while the performance parameters of the permanent magnet may drift, hence the coefficient... The spatial constant region remains unchanged, only the coefficients The specific value may change. Therefore, the above measurement method based on quality difference can only be applied to coefficients within a constant region. The measurement of the value is sufficient for the daily calibration of the magnetic circuit parameters. The selection of the voice coil displacement amplitude should not make the voice coil exceed the coefficient The displacement amplitude should be small, about 10 μm, in order to keep the vibration system linear.

[0073] The difference between the two masses rigidly connected to the sensor probe can be controlled without knowing the specific equivalent mass of the vibration system. For example, the simplest method is to experiment with a mass block of known mass rigidly connected to the sensor probe and with no mass load on the sensor probe, respectively. The mass of the additional mass block is the mass difference between the two experiments, and the coefficient .

[0074] According to the measured coil motional impedance amplitude spectrum, the model function of formula (17) is used to obtain the normalized model parameters , and , and by model parameter identification method. If the calculated coefficient and the three normalized model parameters identified are substituted into formula (14) (16), the equivalent model parameters of the sensor vibration system in Figure 3 can be calculated.

[0075] The steps of measuring the electromechanical coupling coefficient and the equivalent model parameters of the vibration system based on the mass difference and the motional impedance model parameter identification method are as follows:

[0076] Step 1: Prepare a mass block, and measure the mass of the mass block using a precision balance M A ;

[0077] Step 2: Measure the motional impedance amplitude spectrum of the sensor coil without additional mass load on the sensor probe Z m1 (j ω ), and identify the normalized model parameters (17) is used to identify the normalized model parameters M m_n1 、 K m_n1 and R m_n1 by model parameter identification method.

[0078] Step 3: Substitute the mass block M AThe amplitude spectrum of the motional impedance of the sensor coil is measured by rigidly connecting a probe to the sensor Z m2 (j ω )|, the normalized model parameters M m_n2 、 K m_n2 and R m_n2 are identified by a model parameter identification method using the model function of equation

[0079] Step 4: Substitute M m_n1 、 M m_n2 and M m = M A into equation (18) to calculate Bl .

[0080] Step 5: Substitute M m_n = M m_n1 、 K m_n =K m_n1 、 R m_n =R m_n1 and the calculated Bl from the previous step into equations (14) ~ (16) to calculate the equivalent model parameters M m 、 K m and R m of the sensor vibration system.

[0081] To further reduce the calculation error, the coefficient calculation method in Step 4 can be repeated by using multiple masses of different masses to obtain the relationship between and , and the coefficient is obtained by linear fitting method, and and are in a linear relationship, and the slope of the straight line is .

[0082] 1.4 Measurement example of coefficients Bl and equivalent model parameters of the vibration system

[0083] ​1.4.1 Experimental additional mass

[0084] The measured mass values of the several mass loads used in the experiment (measured by a balance with accuracy of 1 mg) are shown in Table 1 (in which the case without mass load is numbered as "1"). The 6 mass loads are represented by a column vector , in which the row number represents the load number.

[0085] Table 1 Measured mass values of the several mass loads

[0086]

[0087] 1.4.2 Coefficients Bl Measurement results

[0088] In one single measurement, the 6 mass loads correspond to and the identified are shown in Figure 7 and Figure 8 , respectively. The identified normalized mass and load mass are linearly correlated well, R 2 = 0.99998, and the slope of the fitting curve, i.e. , is 1.0000.

[0089] The experiment is repeated 10 times for each load, and the obtained are shown in Figure 9 . All the are represented by a matrix , in which the row number represents the load number, and the column number represents the experiment sequence number. The coefficient matrix is calculated, in which the element is calculated by

[0090] ;

[0091] The statistical results of the elements in the matrix are shown in Figure 10 . As can be seen from the figure, the average values of the corresponding to the 5 mass differences are close to each other; the random error decreases with the increase of the mass difference. When the mass difference takes the minimum value of 42.0 mg, the random error is the largest (the average value is 8.0350 , the standard deviation is 0.0881 , and the coefficient of variation is 1.0961%); when the mass difference increases to 788.9 mg, the random error is reduced to the minimum (the average value is 8.1176 , the standard deviation is 0.0052 ​, the coefficient of variation is 0.0639%). The average value of 10 repeated experiments is taken as the additional mass Linear fitting is performed on the average value of 10 repeated experiments Figure 11 . Figure 11 The slope of the straight line in the graph is , so the solution is 8.1176 Web∙m -1 This value is closer to the calculated value when the mass difference is 788.90 mg.

[0092] From the above analysis, it can be seen that using a larger mass difference is beneficial to reducing random errors. However, the upper limit of the mass difference is constrained by the change in the balance position of the voice coil caused by it. The elastic coefficient of the sensor spring used in the experiment is about 1000 kg∙s -2 The position change caused by the mass load of 788.9 mg is about 8 μm, which can be considered to meet the constraint requirement.

[0093] 1.4.3 Measurement results of equivalent model parameters of the vibration system

[0094] Using the data without mass load on the 0 probe, the normalized elastic coefficient is obtained, and the already measured coefficient (8.1176 obtained by linear fitting method using 10 repeated experimental data) is substituted into (14) to obtain the equivalent elastic coefficient measurement results shown in Table 2.

[0095] Table 2 Measurement results of equivalent elastic coefficient

[0096]

[0097] The without mass load on the probe is the initial equivalent mass of the sensor vibration system . Using the same method, the measured is shown in Table 3.

[0098] Table 3 Measurement results of initial equivalent mass of the vibration system

[0099]

[0100] Using the same method, the initial equivalent damping of the vibration system without mass load on the probe is measured, and the results are shown in Table 4.

[0101] Table 4 Measurement results of initial equivalent damping of the vibration system

[0102]

[0103] The application discloses a method for measuring the electromechanical coupling coefficient and equivalent model parameters of a blood viscoelasticity sensor, which comprises the following steps: establishing an equivalent model of a mechanical vibration system of the blood viscoelasticity sensor in operation and an equivalent circuit of a coil in the sensor, deriving a formula of a dynamic impedance module of the coil, loading loads with different masses on a sensor probe, calculating M m_n1 、 K m_n1 、 R m_n1 、 M m_n2 、 K m_n2 and R m_n2 ; thereby calculating the electromechanical coupling coefficient Bl and the equivalent model parameters of the sensor vibration system M m 、 K m and R m ; through the above steps, the viscoelasticity sensor does not need to be detached from the system, does not depend on specific tooling, and is simple to operate, only needs to introduce load masses on the sensor probe, and utilizes a dynamic impedance measurement system (which is generally included in a blood viscoelasticity measurement system based on the sensor itself), so that the "in-system" measurement can be realized, and the convenience of daily calibration of the sensor magnetic circuit parameters and mechanical system parameters in the blood viscoelasticity measurement system is greatly improved.

[0104] The above examples only express several embodiments of the application, and the description is relatively specific and detailed, but it cannot be understood as a limitation on the scope of the patent. It should be pointed out that, for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the application, and the above examples are equivalent modifications and evolutions according to the essential technology of the application, which all belong to the protection scope of the application.

Claims

1. A method for measuring the electromechanical coupling coefficient and equivalent model parameters of a blood viscoelasticity sensor, characterized in that, comprising the steps of: S1: Establish the equivalent model of the mechanical vibration system of the blood viscoelasticity sensor, and the model parameters include the equivalent mass block mass M m , spring elastic coefficient K m , damper damping coefficient R m , and electromechanical coupling coefficient; S2: Establish the equivalent circuit of the coil in the sensor, according to the equivalent circuit, the motional impedance of the coil , is the angular frequency, is the imaginary unit; the modulus of , , and are normalized by the relative constant , , , ; the normalized , are substituted into the expression of , and the result is ; S3: load a mass of M m1 of the load on the sensor probe, the balance position difference of the coil is less than or equal to 10 μm, and the dynamic impedance amplitude values corresponding to at least three different angular frequencies of the sensor coil are measured Z m1 (j ω ) data, at least three and the corresponding Z m1 (j ω ) data are substituted into the formula , and M m_n1 , K m_n1 and R m_n1 are calculated; S4: load a mass of M m2 the load on the sensor probe, M m2 is not equal to M m1 , the balance position difference of the coil is less than or equal to 10 μm, and the dynamic impedance amplitude corresponding to at least three different angular frequencies of the sensor coil is measured Z m2 (j ω ) data, at least three and the corresponding Z m2 (j ω ) data are substituted into the formula , and M m_n2 , K m_n2 and R m_n2 ; S5: the M m1 , M m2 , M m_n1 and M m_n2 substituting , the electromechanical coupling coefficient Bl ; S6: the M m_n =M m_n1 、K m_n= K m_n1 、R m_n =R m_n1 and Bl substituting , , , the equivalent model parameters of the sensor vibration system are calculated M m , K m and R m .

2. The method of claim 1, wherein the method further comprises: determining the mechanical coupling coefficient of the sensor. In step S1, based on the equivalent model of the mechanical vibration system, in the case of time-harmonic, the phasor representation of the probe motion equation is wherein V p is the phasor of the probe motion velocity; F m is the phasor of the driving force on the probe, provided by the Lorentz force on the coil, wherein I c is the phasor of the current in the coil; The electromechanical coupling coefficient is defined by the following equation: wherein, is a segment conductor vector line element of the coil, is a magnetic flux density vector, denotes the closed loop geometry of the coil, the coefficient determines the driving force of the sensor and the induced electromotive force in the coil, i.e. the electromechanical coupling coefficient of the electromechanical coupling system formed by the sensor.

3. The method of claim 1, wherein: In step S2, the coil equivalent impedance is where is the coil terminal voltage, is the current in the coil, is the DC resistance of the coil, is the coil inductance, the term is the motional impedance of the coil.

4. The method of claim 1, wherein the method further comprises: determining the mechanical coupling coefficient of the sensor. In steps S3 and S4, the corresponding M m_n , K m_n and R m_n At this time, any one of a least square type identification method, a gradient correction identification method, or a probability density approximation identification method is used.

5. The method of claim 1, wherein: In steps S3 and S4, M m1 is 0, i.e. no additional mass load on the sensor probe; M m2 is a mass of M m2 a mass of 0.5 mg, in step S4 the mass M m2 is rigidly connected to the probe of the sensor for the motional impedance amplitude measurement of the sensor coil.

6. The method of claim 1, wherein: In step S4, the experiment is repeated with a plurality of masses of different quality, and the relationship and is determined, and the coefficient is determined by linear regression, and are linearly related, and the slope of the straight line is .

7. The method of claim 1, wherein: In step S1, the mass of the equivalent mass block wherein, M r represents the additional radiating mass of the two spring radiating acoustic field of the vibrating viscoelastic sensor; M ʹ m0 represents the sum of the probe's own mass and the equivalent mass of the spring.

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