Laboratory measurement method and device for viscoelastic property of semi-solid biological material

Abstract

The invention discloses laboratory equipment for measuring the viscoelastic property of a semi-solid biological material and a measuring method thereof, and the measuring method comprises the following steps: S1, calculating the propagation velocity v (w) of shear wave signals at different frequencies w based on related parameters of the shear wave signals of a semi-solid biological material sample; s2, calculating the complex shear modulus G * (w) of the semi-solid biological material based on the propagation velocity v (w); and S3, fitting the propagation velocity v (w) and the complex shear modulus G * (w) based on an initial viscoelastic model, extracting model parameters, and representing the viscoelastic property of the semi-solid biological material. According to the method, the relationship between the wave velocity and the frequency of the shear wave is accurately measured, the model parameters are extracted based on the initial viscoelastic model, and the viscoelastic property of the semi-solid biological material can be comprehensively represented. And the device is flexible in design, is suitable for testing different types of semi-solid biological materials, and has the advantages of high precision and high sensitivity.

Description

Technical Field

[0001] The invention relates to the field of viscoelastic property measurement, and in particular to a laboratory measurement method and equipment for viscoelastic properties of semisolid biomaterials. Background Art

[0002] Viscoelastic properties refer to the fact that when a material is subjected to external forces, it exhibits both the properties of an elastic solid and the properties of a viscous fluid. Semisolid biomaterials have unique properties and functions in vivo or in bio-related applications due to their viscoelastic properties.

[0003] Existing methods for measuring the viscoelastic properties of semi-solid biomaterials have limitations in the accuracy of wave velocity measurement and frequency response range, and the measuring equipment needs to be specially modulated before each use, which lacks flexibility. Summary of the invention

[0004] In view of this, the present invention proposes a laboratory measurement method for the viscoelastic properties of solid biomaterials, comprising:

[0005] S1: Based on the relevant parameters of the shear wave signal of the semi-solid biomaterial sample, the propagation velocity v(w) of the shear wave signal at different frequencies w is calculated;

[0006] S2: Calculate the complex shear modulus G of the semisolid biomaterial based on the propagation velocity v(w) * (w);

[0007] S3: Fitting the propagation velocity v(w) and complex shear modulus G based on the initial viscoelastic model * (w), model parameters are extracted through error functions to characterize the viscoelastic properties of semisolid biomaterials.

[0008] According to a preferred embodiment, in S1, the relevant parameters include the frequency, propagation time and traversal distance of the shear wave signal.

[0009] According to a preferred embodiment, the complex shear modulus G of the semisolid biomaterial is calculated based on the propagation velocity v(w). * The calculation formula of (w) is: Where ρ is the density of the semi-solid biomaterial sample.

[0010] According to a preferred embodiment, in S3, the model parameters extracted by the initial viscoelastic model include:

[0011] G0, is the complex shear modulus G * The real part of (w) is the energy storage part;

[0012] η, is the viscosity of the semisolid biomaterial sample;

[0013] α, is the order of the fractional derivative;

[0014] The model expression is: G * (w) = G0 + iη (w α ), where i is the imaginary unit, w α represents the frequency at order α.

[0015] Accordingly, the present invention also proposes a laboratory measuring device for the viscoelastic properties of solid biomaterials, which is used to implement the above method, comprising:

[0016] Shear wave generator: used to generate shear waves of specific frequency and waveform on one side of the sample;

[0017] Shear wave sensor: located on the other side of the sample, used to receive the shear wave propagated from the shear wave generator to the other side of the sample and record the waveform information of the shear wave;

[0018] Measuring unit: connected to the shear wave generator and the shear wave sensor, used to measure the distance between the shear wave generator and the shear wave sensor, and the flight time of the shear wave;

[0019] Control and data processing unit: used to control the waveform and frequency of the shear wave generator, collect data from the shear wave sensor and the measurement unit, and extract model parameters based on the above data to characterize the viscoelastic properties of semi-solid biomaterials.

[0020] The present invention can fully characterize the viscoelastic properties of semi-solid biomaterials by accurately measuring the relationship between the velocity and frequency of shear waves and extracting model parameters based on the initial viscoelastic model and error function. In addition, the device is flexible in design and suitable for testing different types of semi-solid biomaterials, with the advantages of high precision and high sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a flow chart of a laboratory method for measuring viscoelastic properties of a semisolid biomaterial of the present invention;

[0022] Figure 2 Schematic diagram of a laboratory device for measuring viscoelastic properties of semisolid biomaterials according to the present invention. DETAILED DESCRIPTION

[0023] Viscoelastic properties refer to the fact that when a material is subjected to external forces, it exhibits both the properties of an elastic solid and the properties of a viscous fluid. Semisolid biomaterials have unique properties and functions in vivo or in bio-related applications due to their viscoelastic properties.

[0024] Existing methods for measuring the viscoelastic properties of semi-solid biomaterials have limitations in the accuracy of wave velocity measurement and frequency response range, and the measuring equipment needs to be specially modulated before each use, which lacks flexibility.

[0025] In view of this, the present invention proposes a method for measuring the viscoelastic properties of semi-solid biomaterials, such as Figure 1 As shown, including:

[0026] S1: Based on the relevant parameters of the shear wave signal of the semi-solid biomaterial sample, the propagation velocity v(w) of the shear wave signal at different frequencies w is calculated;

[0027] S2: Calculate the complex shear modulus G of the semisolid biomaterial based on the propagation velocity v(w) * (w);

[0028] S3: Fitting the propagation velocity v(w) and complex shear modulus G based on the initial viscoelastic model * (w), model parameters are extracted through error functions to characterize the viscoelastic properties of semisolid biomaterials.

[0029] The present invention can comprehensively characterize the viscoelastic properties of semi-solid biomaterials by accurately measuring the relationship between the wave velocity and frequency of the shear wave and extracting model parameters based on an initial viscoelastic model and an error function.

[0030] Furthermore, in S1, the relevant parameters include the waveform, propagation time and distance traveled of the shear wave signal. Since the shear wave signal can be approximately regarded as uniform motion in the semi-solid biomaterial, a simple uniform motion formula can be used to calculate the wave velocity. That is, the wave velocity v(w) is equal to the distance traveled d divided by the propagation time t. Repeat the above steps and calculate the wave velocity for the shear wave signal at each frequency to obtain frequency-dependent wave velocity data.

[0031] In the above, the number of frequency groups and the difference between two adjacent frequency groups should be determined according to the viscoelastic properties of the actual semi-solid biomaterial and the required measurement accuracy, and the present invention does not impose any restrictions. Among them, if a semi-solid biomaterial with higher accuracy or high value or potential is required, a higher number of groups and a smaller difference can be selected within a reasonable range.

[0032] Further, in S2, the complex shear modulus G of the semisolid biomaterial is calculated based on the propagation velocity v(w). * The calculation formula of (w) is: Where ρ is the density of the semi-solid biomaterial sample.

[0033] Among them, semi-solid biomaterials can be approximately regarded as objects with uniformly distributed mass, so the density ρ can be calculated by measuring its volume v and mass m.

[0034] Among them, the complex shear modulus G * (w) includes the energy storage part and the energy consumption part of the material.

[0035] Furthermore, in S3, the model parameters extracted by the initial viscoelastic model include:

[0036] G0, is the complex shear modulus G * The real part of (w) is the energy storage part;

[0037] η, is the viscosity of the semisolid biomaterial sample;

[0038] α, is the order of the fractional derivative;

[0039] The model expression is: G * (w) = G0 + iη (w α ), where i is the imaginary unit, w α represents the frequency at order α.

[0040] Complex shear modulus G * The energy dissipation part of (w) is the viscosity η and the frequency w representing the αth order α The product of i and iη(w α ).

[0041] Furthermore, when the initial viscoelastic model is fitted, the error function is: Among them, n represents the number of data groups, σ m is the standard error of the mth group of data points, which is used to weight the contribution of each data point. If the standard errors of all data points are the same, σ can be omitted m , v m The value representing the speed of the mth group of data, G * (w) m represents the complex shear modulus G of the mth group of data * The value of (w).

[0042] The above uses the mean square error to calculate the average value of the square of the difference between the model prediction value and the experimental data value, 1, 1...,..., to make an error function judgment,

[0043] Furthermore, the minimum value of the error function is calculated based on the gradient algorithm, and the model parameters at this minimum value are the model parameters that ultimately characterize the viscoelastic properties of the semi-solid biomaterial, wherein the steps of the gradient algorithm include repeatedly calculating the gradient and updating the parameters until a pre-determined standard is met. The pre-determined standard is one or more of the following: reaching a predetermined number of iterations, the error function is reduced to below a certain threshold, or the norm of the gradient is less than a certain value.

[0044] The specific steps include:

[0045] In each iteration, the current error function is calculated The gradient of the error function relative to the model parameters is differentiated to obtain the degree of influence of each parameter on the error function.

[0046] Using the calculated gradient information, update the model parameters according to the gradient descent method, and move a certain step size in the opposite direction of the gradient, that is, the direction where the error decreases fastest.

[0047] After each parameter update, it is necessary to check whether the above predetermined convergence conditions are met. If the convergence conditions are not met, repeat the above steps of calculating the gradient and updating the parameters.

[0048] When the algorithm converges, the current model parameters are considered to be the parameters that can best characterize the viscoelastic properties of the semi-solid biomaterial. These parameters are output to characterize the viscoelastic properties of the semi-solid biomaterial.

[0049] Accordingly, the present invention also provides a laboratory device for measuring the viscoelastic properties of semi-solid biomaterials, which is used to implement the above-mentioned measurement method, such as Figure 2 As shown, specifically including:

[0050] Shear wave generator: used to generate shear waves of specific frequency and waveform on one side of the sample. By precisely controlling the parameters of the shear wave, the response of biomaterials under different conditions can be systematically studied, thereby gaining a more comprehensive understanding of their viscoelastic properties.

[0051] Shear wave sensor: located on the other side of the sample, used to receive the shear wave propagated from the shear wave generator to the other side of the sample and record the waveform information of the shear wave;

[0052] Measuring unit: connected to the shear wave generator and the shear wave sensor, used to measure the distance between the shear wave generator and the shear wave sensor, and the flight time of the shear wave;

[0053] Control and data processing unit: used to control the waveform and frequency of the shear wave generator, collect data from the shear wave sensor and the measurement unit, and extract model parameters based on the above data to characterize the viscoelastic properties of semi-solid biomaterials.

[0054] The specific processing steps of the control and data processing unit include:

[0055] S1: Based on the relevant parameters of the shear wave signal of the semi-solid biomaterial sample, the propagation velocity v(w) of the shear wave signal at different frequencies w is calculated. The relevant parameters include the frequency, propagation time and distance of the shear wave signal;

[0056] S2: Calculate the complex shear modulus G of the semisolid biomaterial based on the propagation velocity v(w) * (w), calculate the complex shear modulus G of the semisolid biomaterial based on the propagation velocity v(w) * The calculation formula of (w) is: Where, ρ is the density of the semisolid biomaterial sample;

[0057] S3: Fitting the propagation velocity v(w) and complex shear modulus G based on the initial viscoelastic model * (w), extracting model parameters through error function to characterize the viscoelastic properties of semi-solid biomaterials; wherein the model parameters extracted by the initial viscoelastic model include:

[0058] G0, is the complex shear modulus G * The real part of (w) is the energy storage part;

[0059] η, is the viscosity of the semisolid biomaterial sample;

[0060] α, is the order of the fractional derivative;

[0061] The model expression is: G * (w) = G0 + iη (w α ), where i is the imaginary unit, w α represents the frequency at the αth order. When the initial viscoelastic model is fitted, the preferred error function is: Further, when the initial viscoelastic model is fitted, the preferred error function is: Among them, n represents the number of data groups, σ m is the standard error of the mth group of data points, which is used to weight the contribution of each data point. If the standard errors of all data points are the same, σ can be omitted m , v m The value representing the speed of the mth group of data, G * (w) m represents the complex shear modulus G of the mth group of data * The value of (w).

[0062] The minimum value of the error function is calculated based on the gradient algorithm, and the model parameters at this minimum value are the model parameters that ultimately characterize the viscoelastic properties of the semi-solid biomaterial, wherein the steps of the gradient algorithm include repeatedly calculating the gradient and updating the parameters until a predetermined standard is met, and the predetermined standard is one or more of the following: reaching a predetermined number of iterations, the error function is reduced to below a certain threshold, or the norm of the gradient is less than a certain value.

[0063] In the above, each module is independently configured, and has the characteristics of flexible design, which is suitable for different types of semi-solid biomaterial testing, and has the advantages of high precision and high sensitivity.

[0064] The above is a detailed introduction to a laboratory measurement method and equipment for the viscoelastic properties of a semi-solid biomaterial provided by an embodiment of the present invention. The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the embodiments can be referenced to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, the present invention can also be improved and modified in several ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0065] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0066] The steps of the method or algorithm described in conjunction with the embodiments disclosed herein may be implemented directly using hardware, a software module executed by a processor, or a combination of the two. The software module may be placed in a random access memory (RAM), a memory, a read-only memory (ROM), an electrically programmable ROM, an electrically erasable programmable ROM, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

Claims

1. A method for measuring the viscoelastic properties of semisolid biomaterials, characterized in that: include: S1: Based on the relevant parameters of the shear wave signal of the semi-solid biomaterial sample, the propagation velocity v(w) of the shear wave signal at different frequencies w is calculated; S2: Calculate the complex shear modulus G of the semisolid biomaterial based on the propagation velocity v(w) * (w); S3: Fitting the propagation velocity v(w) and complex shear modulus G based on the initial viscoelastic model * (w), model parameters are extracted through error functions to characterize the viscoelastic properties of semisolid biomaterials.

2. The method for measuring viscoelastic properties of semisolid biomaterials according to claim 1, characterized in that: In S1, the relevant parameters include the frequency, propagation time and traversal distance of the shear wave signal.

3. The method for measuring viscoelastic properties of semisolid biomaterials according to claim 1, characterized in that: In S2, the complex shear modulus G of the semisolid biomaterial is calculated based on the propagation velocity v(w). * The calculation formula of (w) is: Where ρ is the density of the semi-solid biomaterial sample.

4. The method for measuring viscoelastic properties of semisolid biomaterials according to claim 1, characterized in that: In S3, the model parameters extracted by the initial viscoelastic model include: G0, is the complex shear modulus G * The real part of (w) is the energy storage part; η, is the viscosity of the semisolid biomaterial sample; α, is the order of the fractional derivative; The model expression is: G * (w) = G0 + iη (w α ), where i is the imaginary unit, w α represents the frequency at order α.

5. A laboratory device for measuring the viscoelastic properties of semisolid biomaterials, characterized in that include: Shear wave generator: used to generate shear waves of specific frequency and waveform on one side of the sample; Shear wave sensor: located on the other side of the sample, used to receive the shear wave propagated from the shear wave generator to the other side of the sample and record the waveform information of the shear wave; Measuring unit: connected to the shear wave generator and the shear wave sensor, used to measure the distance between the shear wave generator and the shear wave sensor, and the flight time of the shear wave; Control and data processing unit: used to control the waveform and frequency of the shear wave generator, collect data from the shear wave sensor and the measurement unit, and extract model parameters based on the above data to characterize the viscoelastic properties of semi-solid biomaterials.

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