CN102258371A - Device and method for detecting foreign matters in skin on basis of hollow-core sensor - Google Patents

Abstract

The invention belongs to the technical field of electromagnetic sensors and relates to device for detecting tumors or foreign matters in the skin on the basis of a hollow-core sensor. The device comprises the hollow-core sensor, a signal generation unit, a signal acquisition unit, a power amplifier and an upper computer, wherein the hollow-core sensor is a hollow-core coil and is vertically arranged on the position a certain distance above the skin to be detected; and the upper computer controls the current excitation signal generation unit to apply an exciting current signal on the hollow-core coil, and an induction signal unit is utilized for measuring an induction voltage of a phase which has a 90-degree phase difference with the phase of the applied exciting current signal. The invention provides the detecting method for realizing the detecting device simultaneously. The device and the method provided by the invention are more practical and convenient and the detecting device is one of the most-feasible tools for detecting the tumors or the foreign matters in the skin.

Description

A kind of based on foreign body detecting apparatus and method in the skin of hollow-core sensor

Technical field

The invention belongs to the electromagnetic transducer technical field, be specifically related to tumor or foreign body detecting device and measuring method in a kind of skin.

Background technology

Cutaneous tumor is the cell hyperplastic disease that occurs in skin, is a kind of commonly encountered diseases.Betide Intradermal or hypodermic neoplasm, kind is a lot, divides benign tumor and malignant tumor clinically.Malignant tumor can constantly be bred, and causes transfer, and life-threatening is called skin carcinoma.

Foreign body in the skin, for example pencil stub, syringe needle or the like have pain when not only touching, and have bad reaction in skin.Need discovery early, and take out.

At present, tumor or foreign body detecting typically use the skin detection instrument in the skin.The skin detection instrument costs an arm and a leg, and volume is big slightly, and needs contact skin to detect.

Summary of the invention

At above defective and the deficiency that prior art exists, a kind of device that utilizes electromagnetic method to measure interior tumor of skin or foreign body of purpose proposition of the present invention mentioned.The present invention adopts following technical scheme:

A kind of sniffer based on tumor or foreign body in the skin of hollow-core sensor, comprise hollow-core sensor, signal generating unit, signal gathering unit, power amplifier and host computer, described hollow-core sensor is a hollow coil, be vertically placed on the top of skin certain distance to be measured, apply the exciting current signal by host computer control current excitation signal generating unit to hollow coil, and utilize the induced signal unit to measure the induced voltage that differs 90 degree with the exciting current signal phase that is applied.

Sniffer of the present invention, the diameter of described hollow coil can be 5-100mm.The number of turns of coil is between 1-1000; The diameter of coiling is between 0.01mm-10mm.

The present invention provides a kind of detection method based on tumor or foreign body in the skin of hollow-core sensor that adopts said apparatus to realize simultaneously, comprises the following steps:

(1) tissue in the skin is divided into the n layer, sets the initial conductivity σ of each layer _γ=σ ₁L σ _n,

(2) hollow-core sensor is placed from the normal skin certain height, establish the height l of coil bottom ₁, the height of coil top is l ₂, the number of turn of coil is N, and internal diameter and external diameter are r1 and r2, and the inductance value of establishing coil is L ₀, establishing the hollow-core sensor driving frequency is ω ₁L ω _m, calculate inductance value variable quantity under each different driving frequencies according to following formula:

$\mathrm{\ΔL}\left(\mathrm{\ω}\right)=K{\∫}_0^{\∞}\frac{P^2\left(\mathrm{\α}\right)}{{\mathrm{\α}}^6}A\left(\mathrm{\α}\right)\frac{U_{12}}{U_{22}}\mathrm{d\α},$ Wherein,

U=H ₂H ₁H ₀, U is 2 * 2 matrixes, U ₁₂Be the number of this matrix first row secondary series, U ₂₂Be the number of the matrix second row secondary series,

$H_k=\frac{1}{2}\left[\begin{array}{c}(1-+\frac{{\mathrm{\α}}_k}{{\mathrm{\α}}_{k+1}})e^{({\mathrm{\α}}_{k+1}-{\mathrm{\α}}_k)\·z_k},(1-\frac{{\mathrm{\α}}_k}{{\mathrm{\α}}_{k+1}})e^{({\mathrm{\α}}_{k+1}+{\mathrm{\α}}_k)\·z_k}\\ (1-\frac{{\mathrm{\α}}_k}{{\mathrm{\α}}_{k+1}})e^{(-{\mathrm{\α}}_{k+1}-{\mathrm{\α}}_k)\·z_k},(1+\frac{{\mathrm{\α}}_k}{{\mathrm{\α}}_{k+1}})e^{({\mathrm{\α}}_k-{\mathrm{\α}}_{k+1})\·z_k}\end{array}\right],$

$P\left(\mathrm{\α}\right)={\∫}_{{\mathrm{\αr}}_1}^{\mathrm{\α}{r}_2}x{J}_1\left(x\right)\mathrm{dx},$

$K=\frac{\mathrm{\π}{\mathrm{\μ}}_0{N}^2}{{(l_1-l_2)}^2{(r_1-r_2)}^2},$

${\mathrm{\α}}_k=\sqrt{{\mathrm{\α}}^2+\mathrm{j\ω}{\mathrm{\σ}}_k{\mathrm{\μ}}_k},$

In the formula, α is a spatial frequency variable; ω is the angular frequency of pumping signal; U and H are transmission matrixs; K is an amplification coefficient, J ₁(x) be first kind first-order bessel function; z _kBe the interface depth between k and the k+1 layer; σ _kThe electrical conductivity of expression k layer, μ _kThe pcrmeability of expression k layer, μ _k=1;

(3), calculate the inductance value under the driving frequency of each setting according to the inductance value variable quantity;

(4) applying exciting current respectively to hollow-core sensor is I, frequency is each driving frequency pumping signal of above-mentioned setting, gather its induced signal induced voltage U by signal gathering unit, and send into host computer, obtain the inductance measuring value of pick off by induced voltage U and exciting current I;

(5) seek frequency sweep inductance value under the least square meaning, obtain the conductivity of normal skin ₁ ^/L σ _n ^/, and it is existed in the host computer, as calibration value;

(6) measure skin to be measured again, repeating step (1) measures the electrical conductivity of skin to be measured to (5);

(7) host computer is by the electrical conductivity of contrast skin to be measured and the electrical conductivity of normal skin, set a threshold values, when the electrical conductivity of the electrical conductivity of skin to be measured and normal skin gets difference greater than this threshold values, can judge that skin to be measured contains the composition of tumor or foreign body, otherwise not have foreign body.

Step (5) utilizes the Newton-Raphson method to seek frequency sweep inductance value under the least square meaning.

The invention provides a kind of contactless method and survey in the skin whether have tumor or foreign body, can also real-time detection.Compared with prior art, this method is practical, and is convenient, is one of prospecting tools of tumor or foreign body in the most feasible skin.

Description of drawings

Fig. 1 is of the present invention based on foreign body detecting apparatus structure block diagram in the skin of hollow-core sensor.

Specific implementation method

Below in conjunction with drawings and Examples the present invention is further described.

Fig. 1 is based on foreign body detecting apparatus structure block diagram in the skin of hollow-core sensor according to of the present invention.It is made of hollow-core sensor (i.e. coil among the figure, this coil is a kind of hollow coil), signal generating unit, signal gathering unit, power amplifier and host computer six parts.Signal generating unit adopts synthetic (DDS) chip AD7008 of Direct Digital, and this chip can produce the sinusoidal excitation signal of different amplitudes and phase place.The amplitude of pumping signal and phase place can be by computer installations, by being installed on the excitation coil after the power amplifier amplification.The computer control signal collecting unit is to coil collection and the exciting current inductive voltage value of phase difference 90 degree mutually.

Coil is formed by the insulated conductor coiling, and the diameter of coiling is 0.01mm-10mm, and the number of turn of coiling is the 1-1000 circle, and the diameter of coil is 5mm-100mm.Bobbin is that non-conducting material is made, such as plastics etc.

Skin is layer structure, and the detection of tumor or foreign body comprises direct problem and inverse problem in the skin.The coil placement is moved apart from the skin certain altitude, at first demarcate normal skin, electrical conductivity (or pcrmeability) by given normal skin distributes, by certain algorithm is that its corresponding frequency sweep inductance value is calculated in given electrical conductivity (or pcrmeability) distribution, exist in the host computer, as calibration value, this is a direct problem; Measure skin to be measured then, the pumping signal that host computer control signal generating unit sends is connected on the coil 1 through behind the power amplifier, signal gathering unit is gathered induced signal from coil, its output is admitted to host computer, can get the inductance value of pick off by induced voltage and exciting current, be that the frequency sweep inductance value is rebuild the process that electrical conductivity (or pcrmeability) distributes according to certain algorithm again, this is an inverse problem, according to the distribution of conductivity situation of rebuilding, obviously different because of the electrical conductivity or the pcrmeability of tumor or foreign body with the electrical conductivity or the pcrmeability of normal skin, so just can judging, we have or not tumor or foreign body in the skin.

Measuring method specifically may further comprise the steps:

(1) hollow-core sensor is placed from the normal skin certain height, establish coil inductance value be L ₀, and set initial conductivity σ _γ=σ ₁L σ _nThe coil that has recorded, according to algorithm (i), we can calculate certain limit driving frequency ω ₁L ω _mInductance value f (ω ₁L ω _m)=Δ L+L ₀Pumping signal that host computer control signal generating unit sends is gathered induced signal through being connected on the coil 14 signal gathering unit behind the power amplifier from hollow-core sensor, its output is admitted to host computer, and the inductance measuring value that can get pick off by induced voltage U and exciting current I is

(ii) can obtain the conductivity of normal skin according to algorithm ₁ ^/L σ _n ^/Exist in the host computer, as calibration value, demarcating polytype skin is different σ ₁ ^/L σ _n ^/

(2) measure skin to be measured again, repeating step (1) can get the electrical conductivity of skin to be measured;

(3) host computer is by the electrical conductivity of contrast skin to be measured and the electrical conductivity of normal skin, set a threshold values, when the electrical conductivity of the electrical conductivity of skin to be measured and normal skin gets difference greater than this threshold values, can judge that skin to be measured contains the composition of tumor or foreign body, otherwise not have foreign body.

Direct problem algorithm (i):

The algorithm of relevant direct problem, can be referring to C.C.Cheng, C.V.Dodd, and W.E.Deeds, " General analysisof probe coils near stratified conductors, " Int.J.Nondestruct.Test., vol.3, pp.109-130 simply introduces the direct problem algorithm that the present invention adopts below 1971..

The altimeter of coil bottom is shown 11, and the altimeter of coil top is shown 12.The number of turn of coil is N, and internal diameter and external diameter are r1 and r2, and coil height is L=12-11.The air-core circular coil on skin by the skin layer conductivity ₁L σ _nThe inductance that causes is changed to

$\mathrm{\ΔL}\left(\mathrm{\ω}\right)=K{\∫}_0^{\∞}\frac{P^2\left(\mathrm{\α}\right)}{{\mathrm{\α}}^6}A\left(\mathrm{\α}\right)\frac{U_{12}}{U_{22}}\mathrm{d\α}---\left(1\right)$

Wherein,

U＝H ₂·H ₁·H ₀ (2)

U is 2 * 2 matrixes, U ₁₂Be the number of this matrix first row secondary series, U ₂₂Number for the matrix second row secondary series.

$H_k=\frac{1}{2}\left[\begin{array}{c}(1-+\frac{{\mathrm{\α}}_k}{{\mathrm{\α}}_{k+1}})e^{({\mathrm{\α}}_{k+1}-{\mathrm{\α}}_k)\·z_k},(1-\frac{{\mathrm{\α}}_k}{{\mathrm{\α}}_{k+1}})e^{({\mathrm{\α}}_{k+1}+{\mathrm{\α}}_k)\·z_k}\\ (1-\frac{{\mathrm{\α}}_k}{{\mathrm{\α}}_{k+1}})e^{(-{\mathrm{\α}}_{k+1}-{\mathrm{\α}}_k)\·z_k},(1+\frac{{\mathrm{\α}}_k}{{\mathrm{\α}}_{k+1}})e^{({\mathrm{\α}}_k-{\mathrm{\α}}_{k+1})\·z_k}\end{array}\right]---\left(3\right)$

$A\left(\mathrm{\α}\right)={(e^{-\mathrm{\α}{h}_1}-e^{-\mathrm{\α}{h}_2})}^2---\left(4\right)$

$P\left(\mathrm{\α}\right)={\∫}_{{\mathrm{\αr}}_1}^{\mathrm{\α}{r}_2}x{J}_1\left(x\right)\mathrm{dx}---\left(5\right)$

$K=\frac{\mathrm{\π}{\mathrm{\μ}}_0{N}^2}{{(l_1-l_2)}^2{(r_1-r_2)}^2}---\left(6\right)$

${\mathrm{\α}}_k=\sqrt{{\mathrm{\α}}^2+\mathrm{j\ω}{\mathrm{\σ}}_k{\mathrm{\μ}}_k}---\left(7\right)$

Wherein, α is a spatial frequency variable; ω is the angular frequency of pumping signal; U and H are transmission matrixs; K is an amplification coefficient, J ₁(x) be first kind first-order bessel function.Interface depth between k and k+1 layer is z _kσ _kThe electrical conductivity of expression k layer, μ _kThe pcrmeability of expression k layer, here to the measurement of skin, μ as can be known _k=1.

The inverse problem algorithm is (ii):

The algorithm of relevant inverse problem, can referring to-, " Employment of regularization method in some problemof geophysical interpretation; " Izv.An.Sssr.Fiz.Zem., vol.1, pp.38-48 simply introduces the plan problem algorithm that the present invention adopts below 1975..

The present invention utilizes the Newton-Raphson method to seek the coincideing of frequency sweep inductance value under the least square meaning, and this is a kind of typical inverse problem method for solving.May be defined as:

(1) L ₀∈ R ^mThe vector that is frequency sweep inductance measurement value under m the frequency is expressed;

(2) σ ∈ R ⁿBe that the distribution of conductivity vector with n degree of freedom is expressed;

(3) f:R ⁿ→ R ^mIt is the function that distribution of conductivity is mapped to frequency sweep inductance measurement value;

(4)

Be based on the calculating inductance measurement value of reconstruction distribution of conductivity and the difference of two squares of the actual measured value of inductance.

Inverse problem is to find σ ^*Make φ reach local minimum at least.φ is differentiated to σ, make that its result is 0 vector, that is:

φ′＝[f′] ^T[f-L ₀]＝0 (8)

F ' adds Bryant (Jacobian) matrix, and it is the matrix of a M * N, is defined as

${\left[f^{\′}\right]}_{i,j}=\frac{\∂f_i}{\∂{\mathrm{\σ}}_j}---\left(9\right)$

Adopt the Tikhonov regularization method, given electrical conductivity initial value vector is σ _γ, and represent f (σ with J _r), then:

Δσ＝[J ^TJ+λ·diag(J ^TJ)] ^-1J ^T[f-L ₀] (10)

λ is a regularization parameter.σ ^*Estimation can be expressed as,

σ＝Δσ+σ _r

Last two formulas are iteration constantly, until finding suitable σ ^*Make φ reach local minimum at least.

Claims (5)

1. sniffer based on tumor or foreign body in the skin of hollow-core sensor, comprise hollow-core sensor, signal generating unit, signal gathering unit, power amplifier and host computer, described hollow-core sensor is a hollow coil, be vertically placed on the top of skin certain distance to be measured, apply the exciting current signal by host computer control current excitation signal generating unit to hollow coil, and utilize the induced signal unit to measure the induced voltage that differs 90 degree with the exciting current signal phase that is applied.

2. the sniffer based on tumor or foreign body in the skin of hollow-core sensor according to claim 1 is characterized in that the diameter of described hollow coil is 5-100mm.

3. the sniffer based on tumor or foreign body in the skin of hollow-core sensor according to claim 1 is characterized in that the number of turns of described coil is between 1-1000; The diameter of coiling is between 0.01mm-10mm.

4. one kind is adopted the described detection method based on tumor or foreign body in the skin of hollow-core sensor of claim 1, comprises the following steps:

(1) tissue in the skin is divided into the n layer, sets the initial conductivity σ of each layer _γ=σ ₁L σ _n,

(2) hollow-core sensor is placed from the normal skin certain height, establish the height l of coil bottom ₁, the height of coil top is l ₂, the number of turn of coil is N, and internal diameter and external diameter are r1 and r2, and the inductance value of establishing coil is L ₀, establishing the hollow-core sensor driving frequency is ω ₁L ω _m, calculate inductance value variable quantity under each different driving frequencies according to following formula:

$\mathrm{\ΔL}\left(\mathrm{\ω}\right)=K{\∫}_0^{\∞}\frac{P^2\left(\mathrm{\α}\right)}{{\mathrm{\α}}^6}A\left(\mathrm{\α}\right)\frac{U_{12}}{U_{22}}\mathrm{d\α},$ Wherein,

U=H ₂H ₁H ₀, U is 2 * 2 matrixes, U ₁₂Be the number of this matrix first row secondary series, U ₂₂Be the number of the matrix second row secondary series,

$H_k=\frac{1}{2}\left[\begin{array}{c}(1-+\frac{{\mathrm{\α}}_k}{{\mathrm{\α}}_{k+1}})e^{({\mathrm{\α}}_{k+1}-{\mathrm{\α}}_k)\·z_k},(1-\frac{{\mathrm{\α}}_k}{{\mathrm{\α}}_{k+1}})e^{({\mathrm{\α}}_{k+1}+{\mathrm{\α}}_k)\·z_k}\\ (1-\frac{{\mathrm{\α}}_k}{{\mathrm{\α}}_{k+1}})e^{(-{\mathrm{\α}}_{k+1}-{\mathrm{\α}}_k)\·z_k},(1+\frac{{\mathrm{\α}}_k}{{\mathrm{\α}}_{k+1}})e^{({\mathrm{\α}}_k-{\mathrm{\α}}_{k+1})\·z_k}\end{array}\right],$

$P\left(\mathrm{\α}\right)={\∫}_{{\mathrm{\αr}}_1}^{\mathrm{\α}{r}_2}x{J}_1\left(x\right)\mathrm{dx},$

$K=\frac{\mathrm{\π}{\mathrm{\μ}}_0{N}^2}{{(l_1-l_2)}^2{(r_1-r_2)}^2},$

${\mathrm{\α}}_k=\sqrt{{\mathrm{\α}}^2+\mathrm{j\ω}{\mathrm{\σ}}_k{\mathrm{\μ}}_k},$

In the formula, α is a spatial frequency variable; ω is the angular frequency of pumping signal; U and H are transmission matrixs; K is an amplification coefficient, J ₁(x) be first kind first-order bessel function; z _kBe the interface depth between k and the k+1 layer; σ _kThe electrical conductivity of expression k layer, μ _kThe pcrmeability of expression k layer, μ _k=1;

(3), calculate the inductance value under the driving frequency of each setting according to the inductance value variable quantity;

(4) applying exciting current respectively to hollow-core sensor is I, frequency is each driving frequency pumping signal of above-mentioned setting, gather its induced signal induced voltage U by signal gathering unit, and send into host computer, obtain the inductance measuring value of pick off by induced voltage U and exciting current I;

(5) seek frequency sweep inductance value under the least square meaning, obtain the conductivity of normal skin ₁ ^/L σ _n ^/, and it is existed in the host computer, as calibration value;

(6) measure skin to be measured again, repeating step (1) measures the electrical conductivity of skin to be measured to (5);

(7) host computer is by the electrical conductivity of contrast skin to be measured and the electrical conductivity of normal skin, set a threshold values, when the electrical conductivity of the electrical conductivity of skin to be measured and normal skin gets difference greater than this threshold values, can judge that skin to be measured contains the composition of tumor or foreign body, otherwise not have foreign body.

5. the detection method of tumor or foreign body is characterized in that in the skin according to claim 4, and step (5) utilizes the Newton-Raphson method to seek frequency sweep inductance value under the least square meaning.