CN104473638A - Mammary tissue elastography detection array structure based on piezoelectric impedance method and detection method of mammary tissue elastography detection array structure - Google Patents

Abstract

The invention discloses a mammary tissue elastography detection array structure based on a piezoelectric impedance method and a detection method of the mammary tissue elastography detection array structure. The detection array structure is characterized in that multiple piezoelectric unit structures are arranged on the internal surface of a supporting frame to form a shape similar to the surface of a breast, and can be worn on the to-be-detected breast of a human body; based on the piezoelectric impedance method, the analysis relationship between the resonance frequency of the piezoelectric unit structures and the elastic information of a to-be-detected sample is obtained by measuring the resonance frequency of piezoelectric parameters such as the admittances and the phases of the piezoelectric unit structures and according to an established corresponding piezoelectric equivalent circuit model. According to the detection method provided by the invention, the specificity is strong; a quantitative detection result can be given; therefore the structure and the method are more applicable for the detection of the breast cancer that a cancer tissue is located in the superficial zone, and the difficult problem that the detection on the superficial tissue is difficultly realized through ultrasonic elastography is solved; the structure and the method are simple and reliable; not only can assistance be provided for the implementation of physical examination by medical workers, but also the daily physical examination in a family can be realized, so the early discovery and the early treatment of related breast diseases can be favourably realized.

Description

Based on Piezoelectric Impedance method Ultrasonic Elastography detection array structure and detection method thereof

Technical field

The invention belongs to medical treatment & health detection field, be specifically related to a kind of Ultrasonic Elastography detection array structure based on Piezoelectric Impedance method and detection method thereof.

Background technology

Mammary gland is one of very important organ of human body, and the sickness rate of the disease relevant to mammary gland is in high always, and such disease has caused significant impact to the normal productive life of resident, needs to give enough attention.And in the disease that these mammary gland is relevant, breast carcinoma is the malignant disease needing to pay close attention to, although it is pointed out that living standard at present and medical condition are in improvement, the sickness rate of breast carcinoma constantly has higher mortality rate in lasting rising always.

The means adopted for this kind of malignant disease are at present the responsive policies early finding early treatment, but the early diagnosis of breast carcinoma cancerous issue still exists challenge: daily palpation needs more rich clinical experience could find getting up early cancerous issue, the health carried out without the common people of correlation experience is checked oneself and may be found hardly; In addition, carcinogenic mammary gland tissue due to its specificity low, not obvious to ultrasonic reflection echo.Thus, the conventional Ultrasound adopted during health check-up detects also more difficult discovery breast carcinoma.

How to solve mammary gland relevant disease especially to find to diagnose with morning the morning of breast carcinoma, become medical profession urgent problem.It is worth noting, having after result of study shows tissue pathological changes, can there is remarkable change in the elastic property such as Young's modulus of its tissue.Based on this characteristic, current Chinese scholars proposes the concept of " elastogram ", namely utilize advanced formation method to the elastic property imaging of tissue, utilize these elastic modelling quantity as diagnosis index to judge whether tissue the degree of pathological changes and diagnosis pathological changes occurs.Current widely used elastography comprises the method such as ultrasonic elastograph imaging UE, nuclear magnetic resonance, NMR elastogram MRI.But breast carcinoma cancerous issue is positioned at shallow top layer, the technology such as ultrasonic elastograph imaging are difficult to accurately find breast cancer tissue due to near-field effect, are therefore badly in need of the elastograph imaging method proposing to be applicable to breast carcinoma.

Summary of the invention

In order to solve above problems of the prior art, the present invention proposes a kind of Ultrasonic Elastography detection system based on Piezoelectric Impedance method and detection method thereof, be applicable to the health monitoring to mammary gland, can carry out and the early diagnosis of mammary gland relevant disease such as breast carcinoma and treatment.

One object of the present invention is to propose a kind of Ultrasonic Elastography detection array structure based on Piezoelectric Impedance method.

Ultrasonic Elastography detection array structure based on Piezoelectric Impedance method of the present invention comprises: multiple piezoelectric unit structure and bracing frame; Each piezoelectric unit structure comprises many support bars, support ring, piezoelectric patches, probe and foil gauge; Wherein, support bar is strip, and support ring is circular, and one end of many support bars intersects at support Ring current distribution, and the other end is evenly fixed on support ring respectively, and the quantity of support bar is even number, forms centrosymmetric structure; Each support bar all arranges piezoelectric patches; On the top of the joining of many support bars, foil gauge is set; The probe of taper is set in the bottom of joining; Multiple piezoelectric unit vibrational power flow is at the inner surface of bracing frame; The probe of each piezoelectric unit structure contacts with testing sample; Piezoelectric patches detects the frequency response curve of the Piezoelectric Impedance parameter of piezoelectric unit structure; Contact pressure between strain measurement probe and sample.

Another object of the present invention is to propose a kind of Ultrasonic Elastography detection system based on Piezoelectric Impedance method.

Ultrasonic Elastography detection system based on Piezoelectric Impedance method of the present invention comprises: detection array structure, Piezoelectric Impedance tester, strain gauge, data collecting card and computer; Wherein, detection array structure comprises multiple piezoelectric unit structure and bracing frame; Each piezoelectric unit structure comprises support ring, many support bars, piezoelectric patches, foil gauge and probes; Wherein, support bar is strip, and support ring is circular, and one end of many support bars intersects at support Ring current distribution, and the other end is evenly fixed on support ring respectively, and the quantity of support bar is even number, forms centrosymmetric structure; Each support bar all arranges piezoelectric patches; On the top of the joining of many support bars, foil gauge is set; The probe of taper is set in the bottom of joining; Multiple piezoelectric unit vibrational power flow, at the inner surface of bracing frame, forms the shape being similar to breast surface; The probe of each piezoelectric unit structure contacts with testing sample; Piezoelectric patches is connected to Piezoelectric Impedance tester by control line, measures the frequency response curve of the Piezoelectric Impedance parameter of piezoelectric unit structure; Foil gauge is connected to strain gauge by control line, the contact pressure between detector probe and sample; Electrical impedance tester and strain gauge are connected to data collecting card respectively; Data collecting card is connected to computer.

The present invention adopts multiple piezoelectric unit vibrational power flow at the inner surface of bracing frame, forms the shape being similar to breast surface, is placed on testing sample, on mammary gland tissue namely to be detected; In the process detected, bracing frame is that multiple piezoelectric unit structure provides support, and can adjust the distance between bracing frame and piezoelectric unit structure, and probe is contacted with testing sample; The probe of each piezoelectric unit structure contacts with testing sample; Contact pressure between strain measurement probe and testing sample; Strain gauge measurement obtains contact pressure, and adjusts contact pressure by the distance between adjustment piezoelectric unit structure and bracing frame; The frequency response curve of the Piezoelectric Impedance parameter (Piezoelectric Impedance parameter comprises admittance G, phase theta and impedance Z) of each piezoelectric unit structure measured by Piezoelectric Impedance tester, obtains the resonant frequency of its Piezoelectric Impedance parameter; Set up the resonant frequency of Piezoelectric Impedance parameter of piezoelectric unit structure and the relation of the Young's modulus of contact point, thus calculate the local Young's modulus of the testing sample that each piezoelectric unit structure detection arrives; The local Young's modulus all piezoelectric unit structures obtained is carried out gathering integrated according to the locus corresponding to piezoelectric unit structure, form Young's modulus distribution figure, this Young's modulus distributes figurebe the Young's modulus distribution of mammary gland, and then tissue health state is diagnosed.

In piezoelectric unit structure, piezoelectric patches is set on a surface of every bar support bar of centrosymmetry distribution, forms monocrystalline piezoelectric cellular construction; Or, at the upper surface of centrosymmetric every bar support bar and lower surface, piezoelectric patches is set respectively, forms bimorph piezo electric cellular construction.

Multiple piezoelectric unit vibrational power flow is at the inner surface of bracing frame, the surface contact of the needle point of each probe and mammary gland tissue to be measured is made by the distance between adjustment piezoelectric unit structure and bracing frame, the curved surface that forms of probe tip is consistent with mammary gland surface thus, the shape of this curved surface is also similar with the shape of breast surface, can be placed on easily on mammary gland tissue to be measured like this and detect.

Each piezoelectric patches in multiple piezoelectric unit structure is connected to a passage of Piezoelectric Impedance tester respectively by control line; Each foil gauge in multiple piezoelectric unit structure is connected to a passage of strain gauge respectively by control line; The present invention adopts and is integrated on bracing frame by many control lines, Piezoelectric Impedance tester and strain gauge is connected to respectively again by bracing frame, thus realize each piezoelectric patches is connected to a Piezoelectric Impedance tester passage respectively by control line, and each foil gauge is connected to a passage of strain gauge respectively by control line.

Another object of the present invention is to provide a kind of Ultrasonic Elastography detection method based on Piezoelectric Impedance method.

Ultrasonic Elastography detection method based on Piezoelectric Impedance method of the present invention, comprises the following steps:

1) be placed on testing sample by detection array structure, the probe of each piezoelectric unit structure contacts with testing sample;

2) contact pressure between strain measurement probe and sample, strain gauge measurement obtains contact pressure, and by the distance between adjustment piezoelectric unit structure and bracing frame, adjustment contact pressure;

3) frequency response curve of the Piezoelectric Impedance parameter of each piezoelectric unit structure measured by Piezoelectric Impedance tester, obtains the resonant frequency of its Piezoelectric Impedance parameter, and strain gauge measurement obtains the contact pressure between probe and sample;

4) data collecting card collection gathers the resonant frequency that Piezoelectric Impedance tester records respectively, and strain gauge measurement obtains the value of contact pressure, and passes to computer;

5) computer is according to the value of resonant frequency and contact pressure, and according to the piezoelectric equivalent circuit model set up and the analytical mechanics relation formula obtained, calculate local elasticity's information that each piezoelectric unit structure of contacting with testing sample records, the local elasticity's information all piezoelectric unit structures obtained is carried out gathering integrated according to the locus corresponding to piezoelectric unit structure, form elastic information distribution figure, thus the health degree of judgement sample.

Wherein, in step 5) in, elastic information comprises elastic property k _twith Young's modulus E _x, the resonant frequency f of piezoelectric unit structure ₀with elastic property k _tbetween meet following relational expression:

$k_t=m_t{\mathrm{\ω}}_0^2+{\stackrel{\‾}{k}}_b{\mathrm{\λ}}_{b0}^3\frac{1+\cos {\mathrm{\λ}}_{b0}L\cosh {\mathrm{\λ}}_{b0}L}{\sin {\mathrm{\λ}}_{b0}L\cosh {\mathrm{\λ}}_{b0}\text{L-cos}{\mathrm{\λ}}_{b0}L\sinh {\mathrm{\λ}}_{b0}L}$

Wherein, ω ₀=2 π f ₀, m _tfor the quality of probe, L is the radius of piezoelectric unit structure, λ _b0for effective wavelength, for Equivalent Beam rigidity.

Further, according to Hertzian contact theory, the Young's modulus E of testing sample can be obtained _xmeet following formula:

$E_x=\frac{E_t\sqrt{\frac{{\left(k_t\right)}^3}{6\mathrm{RF}}}}{\sqrt{\frac{{\left(k_t\right)}^3}{6\mathrm{RF}}}-E_t}$

Wherein, E _tfor the Young's modulus of probe, R is the radius of probe, and F is contact pressure.

Advantage of the present invention

Compared with the elastogram system of conventional cantilever beam formula, the brand-new Ultrasonic Elastography detection system based on Piezoelectric Impedance method proposed by the invention has following difference and advantage:

The present invention devises brand-new piezoelectric unit structure and detection array structure, the shape of detection array structure is similar to breast surface and can wears in human breast to be measured, based on Piezoelectric Impedance method, by measuring the resonant frequency of the piezoelectric parameters such as the admittance of piezoelectric unit structure and phase place, and according to the corresponding piezoelectric equivalent circuit model set up, obtain the analytic relationship between the resonant frequency of piezoelectric unit structure and the elastic information of testing sample.And traditional method adopts piezoelectric cantilever, based on mechanical resonance principle, to be followed the trail of by strain, and according to the mechanical balance model set up, the relation of measured is mechanical oscillation frequencies and testing sample.

Advantage of the present invention is, based on piezoelectric unit structure measurement, its stability is higher, be not subject to extraneous vibration interference, its apply measuring voltage be less than 1V, power and Oscillation Amplitude less, object to be measured can not experience the vibration that test brings; Traditional method adopts strain to follow the trail of, need to use higher voltage (being generally greater than 500V) exciting cantilever beam to produce measurable strain, therefore for the measurement of contact skin, there is larger electric leakage risk, and traditional method adopts pure mechanical balance model to describe piezoelectric vibration, exist compared with the error on broad theory, thus can bring larger measurement error.

The present invention uses the piezoelectric unit structure of a particular design, is integrated into the medical detection array structure being applicable to mammary gland tissue, has built detection system according to this structure, and propose the detection method of the Breast health based on this detection system.Compared to other medical detection meanss, detection method high specificity used in the present invention, the testing result of energy quantitative, and due to its special design, be more suitable for the breast carcinoma that cancerous issue is positioned at shallow top layer, solve a detection difficult problem for the shallow textura epidermoidea that ultrasonic elastograph imaging has been difficult to.The present invention is simple and reliable, and medical worker both can have been assisted to carry out physical examination, also by its miniaturization instrumentation, can make it to be suitable for health daily in family and check oneself, and the morning contributing to mammary gland relevant disease finds and early treatment.

Accompanying drawing explanation

fig. 1for the structural representation of piezoelectric unit structure of the present invention figure, wherein, (a) is the knot meaning of four cross monocrystalline piezoelectric cellular constructions figure, (b) is the signal of four cross bimorph piezo electric cellular constructions figure, (c) is the signal of six 60 ° crossing monocrystalline piezoelectric cellular constructions figure, (d) is the signal of six 60 ° crossing bimorph piezo electric cellular constructions figure;

fig. 2for the structural representation of multiple piezoelectric unit structure distribution of the present invention on testing sample figure;

fig. 3for the signal of the Ultrasonic Elastography detection array structure based on Piezoelectric Impedance method of the present invention figure;

fig. 4for the signal of an embodiment of the Ultrasonic Elastography detection system based on Piezoelectric Impedance method of the present invention figure;

fig. 5for bimorph piezo electric cellular construction of the present invention is equivalent to the signal of twin crystal beam contact vibration model figure;

fig. 6for fig. 5the piezoelectricity equivalent circuit of the twin crystal beam contact vibration model of shown bimorph piezo electric cellular construction equivalence figure.

Detailed description of the invention

Below in conjunction with accompanying drawing, by specific embodiment, set forth the present invention further.

as Fig. 1shown in, piezoelectric unit structure comprises many support bars 21, support ring 22, piezoelectric patches 23, probe 24 and foil gauge 25; Wherein, support bar 21 is strip, and support ring 22 is circular, and one end of many support bars 21 intersects at the center of support ring 22, and the other end is evenly fixed on support ring 22 respectively, and the quantity of support bar 21 is even number, forms centrosymmetric structure; Each support bar 21 all arranges piezoelectric patches 23; On the top of the joining of many support bars, foil gauge 25 is set; The probe 24 of taper is set in the bottom of joining.Piezoelectric patches 23 can be set on a surface of the support bar of centrosymmetry distribution, form monocrystalline piezoelectric cellular construction; Or, piezoelectric patches 23 is set respectively at the upper surface of centrosymmetric support bar and lower surface, forms bimorph piezo electric cellular construction. fig. 1in, (a) is the signal of four cross monocrystalline piezoelectric cellular constructions figure, (b) is the signal of four cross bimorph piezo electric cellular constructions figure, (c) is the signal of six 60 ° crossing monocrystalline piezoelectric cellular constructions figure, (d) is the signal of six 60 ° crossing bimorph piezo electric cellular constructions figure.

as Fig. 2shown in, multiple piezoelectric unit structure 2 is evenly distributed on the curved surface of a semielliptical, forms the shape being similar to breast surface, can wear in mammary gland tissue to be measured.

as Fig. 3shown in, the Ultrasonic Elastography detection array structure based on Piezoelectric Impedance method of the present embodiment comprises: multiple piezoelectric unit structure 2 and bracing frame 1; Multiple piezoelectric unit structures 2 are arranged on the inner surface of bracing frame 1, form the shape being similar to breast surface, adjust the contact pressure between probe and testing sample by the distance between adjustment piezoelectric unit structure and bracing frame.

as Fig. 4shown in, the Ultrasonic Elastography detection system based on Piezoelectric Impedance method of the present embodiment comprises: detection array structure, Piezoelectric Impedance tester 3, strain gauge 4, data collecting card 5 and computer 6; Wherein, the probe of each piezoelectric unit structure contacts with testing sample; Many control line is integrated on bracing frame 1, Piezoelectric Impedance tester 3 and strain gauge 4 is connected to respectively again by bracing frame 1, thus the piezoelectric patches realizing each piezoelectric unit structure is connected to a passage of Piezoelectric Impedance tester 3 respectively by control line, and each foil gauge is connected to a passage of strain gauge 4 respectively by control line; Electrical impedance tester 3 and strain gauge 4 are connected to data collecting card 5 respectively; Data collecting card 5 is connected to computer 6.

Bimorph piezo electric cellular construction is equivalent to as Fig. 5shown twin crystal beam contact vibration model, and set up piezoelectricity equivalent circuit thus figure, as Fig. 6shown in.Detection method of the present invention according to Piezoelectric Impedance method, and sets up piezoelectric equivalent circuit model to calculate the resonant frequency f of piezoelectric unit structure ₀with sample elastic character k _twith sample Young's modulus E _xbetween relation, introduce Cleaning Principle of the present invention below.

For fig. 1in the piezoelectric unit structure that provides, it is essentially centrosymmetric structure, therefore when describing the contact vibration of itself and testing sample, can be reduced to as Fig. 5shown piezoelectric bimorph beam contact vibration model, L is the radius of piezoelectric unit structure, m _tfor the quality of probe, h _sfor a half thickness of probe metal level, h _pfor the thickness of piezoelectric patches. fig. 5in, the contact between the probe of piezoelectric unit structure and sample uses a rigidity to be k _tspring simulate, namely containing the elastic property of sample in this parameter.

The resonant frequency f of piezoelectric unit structure ₀with the elastic property k of sample _tbetween relation can be by as Fig. 6shown equivalent circuit obtains, and the impedance matrix of this equivalent circuit is:

$\left\{\begin{array}{c}{F}_1\\ F_2\\ F_3\\ F_4\\ V\end{array}\right\}=\left[\begin{array}{ccccc}{Z}_{11}& Z_{12}& Z_{13}& Z_{14}& Z_{15}\\ & Z_{22}& Z_{23}& Z_{24}& Z_{25}\\ & & Z_{33}& Z_{34}& Z_{35}\\ & \mathrm{Symm}& & Z_{44}& Z_{45}\\ & & & & Z_{55}\end{array}\right]\left\{\begin{array}{c}{U}_1\\ U_2\\ U_3\\ U_4\\ I\end{array}\right\}---\left(1\right)$

Wherein, F ₁for clamped end shear boundary condition, F ₂for clamped end moment of flexure boundary condition, F ₃for free end shearing boundary condition, F ₄for free end moment of flexure boundary condition, U ₁for clamped end velocity boundary conditions, U ₂for clamped end angular velocity boundary condition, U ₃for free end velocity boundary conditions, U ₄for free end angular velocity boundary condition, V and I is respectively Piezoelectric Impedance tester and is carried in voltage and current on piezoelectric patches.Symm shows that matrix is symmetrical matrix, and each impedance element in matrix can be expressed as:

$Z_{11}=Z_{33}=\frac{{\stackrel{\‾}{K}}_b{\mathrm{\λ}}_b^3}{\mathrm{j\ω}}\frac{-\mathrm{cn}-\mathrm{sm}}{1-\mathrm{cm}}$

$Z_{12}=-Z_{34}=\frac{{\stackrel{\‾}{K}}_b{\mathrm{\λ}}_b^2}{\mathrm{j\ω}}\frac{\mathrm{sn}}{1-\mathrm{cm}}$

$Z_{13}=\frac{{\stackrel{\‾}{K}}_b{\mathrm{\λ}}_b^3}{\mathrm{j\ω}}\frac{s+n}{1-\mathrm{cm}}$

$Z_{14}=-Z_{23}=\frac{{\stackrel{\‾}{K}}_b{\mathrm{\λ}}_b^2}{\mathrm{j\ω}}\frac{-c+m}{1-\mathrm{cm}}$

Z ₁₅＝Z ₃₅＝0 (2)

$Z_{22}=Z_{44}=\frac{{\stackrel{\‾}{K}}_b{\mathrm{\λ}}_b}{\mathrm{j\ω}}\frac{\mathrm{cn}-\mathrm{sm}}{1-\mathrm{cm}}+\frac{N^2}{\mathrm{j\ω}{C}_c}$

$Z_{24}=\frac{{\stackrel{\‾}{K}}_b{\mathrm{\λ}}_b}{\mathrm{j\ω}}\frac{s-n}{1-\mathrm{cm}}-\frac{N^2}{\mathrm{j\ω}{C}_c}$

$Z_{25}=-Z_{45}=\frac{N}{\mathrm{j\ω}{C}_c}$

$Z_{55}=\frac{1}{\mathrm{j\ω}{C}_c}$

Wherein, ω is angle of throw frequency and has ω=2 π f, and f is frequency of vibration, equivalent depth ${\stackrel{\‾}{K}}_b=\frac{2}{3}\mathrm{\ω}[\frac{1}{S_{p_{11}}^E}({(h_p+h_s)}^3-h_s^3)+\frac{1}{S_{s_{11}}}{h}_s^3],N=-\frac{d_{31}}{S_{p_{11}}^E}\mathrm{\ω}\left(\frac{h_p+2h_s}{2}\right),$ d ₃₁and S _s11material parameter respectively, effective wavelength ρ _pand ρ _sthe density of piezoelectric patches and support bar respectively, c=cos λ _bl, s=sin λ _bl, m=cosh λ _bl, n=sinh λ _bl, the electric capacity of piezoelectric beam p ₃₃be the dielectric constant of piezoelectric patches, N is conversion coefficient, and fig. 6in the implication of each impedance element be:

Z _c＝Z ₁₁+Z ₁₂+Z ₁₃-Z ₁₄

Z _d＝Z ₁₂+Z ₁₄+Z ₂₂+Z ₂₄Z _e＝-Z ₁₄-Z ₂₄Z _f＝-Z ₁₂+Z ₁₄(3)

Z _g＝Z ₁₂Z _h＝-Z ₁₂-Z ₁₄Z _i＝-Z ₁₃+Z ₁₄

C _m＝-C _c/N ²

It is theoretical according to equivalent circuit, fig. 6in admittance Y and the relation of angle of throw frequencies omega can be expressed as:

$Y=\mathrm{j\ω}(C_c+\frac{N^2}{{\stackrel{\‾}{K}}_b{\mathrm{\λ}}_b}\frac{-\mathrm{cn}-\mathrm{sm}-\mathrm{cm\β}+\mathrm{\β}}{1+\mathrm{cm}-\mathrm{sm\β}+\mathrm{cn\β}})---\left(4\right)$

Wherein, $\mathrm{\β}=\frac{-{\mathrm{\ω}}^2{m}_t+k_t}{{\stackrel{\‾}{K}}_b{\mathrm{\λ}}_b^3}.$

The concussion frequency of admittance Y when getting maximum in circuit is resonant frequency, and namely (4) formula is at ω ₀=2 π f ₀time get maximum, f ₀for resonant frequency, now β meets 1+cm-sm β+cn β=0, therefore can obtain:

$k_t=m_t{\mathrm{\ω}}_0^2+{\stackrel{\‾}{k}}_b{\mathrm{\λ}}_{b0}^3\frac{1+\cos {\mathrm{\λ}}_{b0}L\cosh {\mathrm{\λ}}_{b0}L}{\sin {\mathrm{\λ}}_{b0}L\cosh {\mathrm{\λ}}_{b0}\text{L-cos}{\mathrm{\λ}}_{b0}L\sinh {\mathrm{\λ}}_{b0}L}---\left(5\right)$

Wherein, further, according to Hertzian contact theory, the Young's modulus E of testing sample can be obtained _xexpression formula:

$E_x=\frac{E_t\sqrt{\frac{{\left(k_t\right)}^3}{6\mathrm{RF}}}}{\sqrt{\frac{{\left(k_t\right)}^3}{6\mathrm{RF}}}-E_t}---\left(6\right)$

In formula, E _tfor the Young's modulus of probe, R is the radius of probe, and F is contact pressure, and these parameters are known.Thus the resonant frequency f obtaining piezoelectric unit structure is being followed the trail of ₀afterwards, therefore according to (5) formula, k is calculated _t, the Young's modulus E of testing sample is calculated further according to (6) formula _x, above (5) formula and (6) formula are the resonant frequency f calculating piezoelectric unit structure based on Piezoelectric Impedance method ₀and the analytical mechanics relation between the elastic information of testing sample.

Ultrasonic Elastography detection method based on Piezoelectric Impedance method of the present invention, comprises the following steps:

1) be placed on testing sample by detection array structure, the probe of each piezoelectric unit structure contacts with testing sample;

2) contact pressure between strain measurement probe and sample, strain gauge measurement obtains contact pressure, and by the distance between adjustment piezoelectric unit structure and bracing frame, adjustment contact pressure;

3) frequency response curve of the Piezoelectric Impedance parameter of each piezoelectric unit structure measured by Piezoelectric Impedance tester, obtains the resonant frequency of its Piezoelectric Impedance parameter, and strain gauge measurement obtains the contact pressure between probe and sample;

4) data collecting card collection gathers the resonant frequency that Piezoelectric Impedance tester records respectively, and strain gauge measurement obtains the value of contact pressure, and passes to computer;

5) computer is according to the value of resonant frequency and contact pressure, and according to the piezoelectric equivalent circuit model set up and the analytical mechanics relation formula obtained, calculate local elasticity's information that each piezoelectric unit structure of contacting with testing sample records, the local elasticity's information all piezoelectric unit structures obtained is carried out gathering integrated according to the locus corresponding to piezoelectric unit structure, form elastic information distribution figure, thus the health degree of judgement sample.

It is finally noted that the object publicizing and implementing example is to help to understand the present invention further, but it will be appreciated by those skilled in the art that: without departing from the spirit and scope of the invention and the appended claims, various substitutions and modifications are all possible.Therefore, the present invention should not be limited to the content disclosed in embodiment, and the scope that the scope of protection of present invention defines with claims is as the criterion.

Claims (8)

1. a Ultrasonic Elastography detection array structure, is characterized in that, described detection array structure comprises: multiple piezoelectric unit structure and bracing frame; Each piezoelectric unit structure comprises many support bars, support ring, piezoelectric patches, probe and foil gauge; Wherein, support bar is strip, and support ring is circular, and one end of many support bars intersects at support Ring current distribution, and the other end is evenly fixed on support ring respectively, and the quantity of support bar is even number, forms centrosymmetric structure; Each support bar all arranges piezoelectric patches; On the top of the joining of many support bars, foil gauge is set; The probe of taper is set in the bottom of joining; Multiple piezoelectric unit vibrational power flow is at the inner surface of bracing frame; The probe of each piezoelectric unit structure contacts with testing sample; Piezoelectric patches detects the frequency response curve of the Piezoelectric Impedance parameter of piezoelectric unit structure; Contact pressure between strain measurement probe and sample.

2. detection array structure as claimed in claim 1, is characterized in that, adjusts the contact pressure between probe and testing sample by the distance between adjustment piezoelectric unit structure and bracing frame.

3. detection array structure as claimed in claim 1, is characterized in that, in piezoelectric unit structure, arranges piezoelectric patches, form monocrystalline piezoelectric cellular construction on a surface of every bar support bar of centrosymmetry distribution; Or, at the upper surface of centrosymmetric every bar support bar and lower surface, piezoelectric patches is set respectively, forms bimorph piezo electric cellular construction.

4. a Ultrasonic Elastography detection system, is characterized in that, described detection system comprises: detection array structure, Piezoelectric Impedance tester, strain gauge, data collecting card and computer; Wherein, detection array structure comprises multiple piezoelectric unit structure and bracing frame; Each piezoelectric unit structure comprises support ring, many support bars, piezoelectric patches, foil gauge and probes; Wherein, support bar is strip, and support ring is circular, and one end of many support bars intersects at support Ring current distribution, and the other end is evenly fixed on support ring respectively, and the quantity of support bar is even number, forms centrosymmetric structure; Each support bar all arranges piezoelectric patches; On the top of the joining of many support bars, foil gauge is set; The probe of taper is set in the bottom of joining; Multiple piezoelectric unit vibrational power flow is at the inner surface of bracing frame; The probe of each piezoelectric unit structure contacts with testing sample; Piezoelectric patches is connected to Piezoelectric Impedance tester by control line, measures the frequency response curve of the Piezoelectric Impedance parameter of piezoelectric unit structure; Foil gauge is connected to strain gauge by control line, the contact pressure between detector probe and sample; Electrical impedance tester and strain gauge are connected to data collecting card respectively; Data collecting card is connected to computer.

5. detection system as claimed in claim 4, it is characterized in that, many control line is integrated on bracing frame, Piezoelectric Impedance tester and strain gauge is connected to respectively again by bracing frame, thus each piezoelectric patches is connected to a passage of Piezoelectric Impedance tester respectively by control line, and each foil gauge is connected to a passage of strain gauge respectively by control line.

6. a Ultrasonic Elastography detection method, is characterized in that, described detection method comprises the following steps:

1) be placed on testing sample by detection array structure, the probe of each piezoelectric unit structure contacts with testing sample;

2) contact pressure between strain measurement probe and sample, strain gauge measurement obtains contact pressure, and by the distance between adjustment piezoelectric unit structure and bracing frame, adjustment contact pressure;

3) frequency response curve of the Piezoelectric Impedance parameter of each piezoelectric unit structure measured by Piezoelectric Impedance tester, obtains the resonant frequency of its Piezoelectric Impedance parameter, and strain gauge measurement obtains the contact pressure between probe and sample;

4) data collecting card collection gathers the resonant frequency that Piezoelectric Impedance tester records respectively, and strain gauge measurement obtains the value of contact pressure, and passes to computer;

5) computer is according to the value of resonant frequency and contact pressure, and according to the piezoelectric equivalent circuit model set up and the analytical mechanics relation formula obtained, calculate local elasticity's information that each piezoelectric unit structure of contacting with testing sample records, the local elasticity's information all piezoelectric unit structures obtained is carried out gathering integrated according to the locus corresponding to piezoelectric unit structure, form elastic information scattergram, thus the health degree of judgement sample.

7. detection method as claimed in claim 6, is characterized in that, in step 5) in, elastic information comprises elastic property k _twith Young's modulus E _x, the resonant frequency f of piezoelectric unit structure ₀with elastic property k _tbetween meet following relational expression:

$k_t=m_t{\mathrm{\ω}}_0^2+{\stackrel{\‾}{k}}_b{\mathrm{\λ}}_{b0}^3\frac{1+\cos {\mathrm{\λ}}_{b0}L\cosh {\mathrm{\λ}}_{b0}L}{\sin {\mathrm{\λ}}_{b0}L\cosh {\mathrm{\λ}}_{b0}L-\cos {\mathrm{\λ}}_{b0}L\sinh {\mathrm{\λ}}_{b0}L}$

Wherein, resonant angular frequency ω ₀=2 π f ₀, f ₀for resonant frequency, m _tfor the quality of probe, L is the radius of piezoelectric unit structure, λ _b0for effective wavelength, for Equivalent Beam rigidity.

8. detection method as claimed in claim 7, is characterized in that, further according to Hertzian contact theory, can obtain the Young's modulus E of testing sample _xmeet following formula:

$E_x=\frac{E_t\sqrt{\frac{{\left(k_t\right)}^3}{6\mathrm{RF}}}}{\sqrt{\frac{{\left(k_t\right)}^3}{6\mathrm{RF}}}-E_t}$

Wherein, E _tfor the Young's modulus of probe, R is the radius of probe, and F is contact pressure.