CN1010252B - Six-ring electrode technology for measuring biological dielectric character - Google Patents
Six-ring electrode technology for measuring biological dielectric characterInfo
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- CN1010252B CN1010252B CN 88100107 CN88100107A CN1010252B CN 1010252 B CN1010252 B CN 1010252B CN 88100107 CN88100107 CN 88100107 CN 88100107 A CN88100107 A CN 88100107A CN 1010252 B CN1010252 B CN 1010252B
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- electrode
- tissue
- measuring
- ring
- dielectric property
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- Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
- Investigating Or Analysing Biological Materials (AREA)
Abstract
On the basis of the analysis of the present research conditions of the dielectric property of biological tissues and the existing problems in measurement, the present invention relates to a six ring electrode technology as an electrode technology for measuring the dielectric property of biological tissues. The electrode technology integrates a measuring electrode with a protective electrode and preferably overcomes the problems existing in other past electrode technologies. The electrode is justified in theory through the numerical analysis of an electric field. Experiments prove that the technology has the characteristics of convenient sample preparation, no strict requirement for the size of measured tissues, high measuring precision, realization of in vivo measurement, etc., which have superiority over the characteristics of other electrode technologies. The present invention can also be used for measuring the dielectric property of liquid and colloid.
Description
Six-ring electrode device of the present invention is applicable to the dielectric property measurement of low frequency frequency range tissue.
The electrode assembly that is used for the dielectric property measurement of low frequency frequency range biological tissue is at present mainly used four electrode technologies, and its measuring principle as shown in Figure 1.The four-probe measurement technology is made of two pairs of electrodes, and a pair of with constant exchange current introducing biological tissue, another draws the current potential at tested position to electrode.Adopt four electrode technologies, before measuring, biological tissue's sample must be cut into certain shape and size by certain requirement.This just makes the isolated time of tissue prolong, and adds cutting processing repeatedly, must destroy the normal physiological state of biological tissue, thereby bring bigger error to measurement.Other four electrode technologies are uncontrollable to the distribution of exciting current in tissue, and the distribution of electric current is relevant with size, the shape of tissue.So, adopt four electrode technologies to guaranteeing in the tissue or the even or regular relatively difficulty of the Electric Field Distribution in certain scope in the tissue, cause tissue different, the generation measuring error partly to the contribution difference of survey dielectric property.And this technology generally can not be used for directly biological tissue being carried out the measurement of dielectric property on life entity.
The four-probe measurement device (as shown in Figure 3) that is made of four needle electrodes can solve the dielectric property of measuring biological tissue on life entity.But it is uniformly that this kind electrode requires tissue, tissue volume big (approximate infinitely great).At tissue hour, the skewness of electric current, thereby produce bigger measuring error.
The objective of the invention is to seek a kind of new biological tissue's device for measuring dielectric characteristics.It makes measured biological tissue's sample production simple, convenient, reduces the isolated time of tissue, avoids the cutting processing repeatedly to tested tissue, thereby reduces the measuring error of bringing thus.It can control the flow direction of electric current in the tested tissue, make current density in tissue be evenly distributed or regular, improve measuring accuracy, and can directly on life entity, measure tissue.
The objective of the invention is to realize in the following manner.
Six-ring electrode of the present invention is made of potential electrode and guard electrode, shown in Fig. 4,5.Potential electrode is made of four metal rings on the insulation disk, and outer shroud and interior ring are galvanic electrode, and two rings between the inner and outer ring are voltage electrode, the midpoint of two voltage electrodes between the inner and outer ring distance.Guard electrode is made of two metal rings of another insulation on disk, and these two annulus also are galvanic electrode, and is identical with galvanic electrode diameter in the potential electrode.
The dielectric property of biological tissue comprises DIELECTRIC CONSTANT and two parameters of electrical conductivity σ (this biological tissue's dielectric property measure two parameters being asked) just.Suppose that biological tissue satisfies, isotropy and homogeneity, promptly ε do not change with σ with excitation and organize in each point identical, impressed frequency is the excitation of ω, then the electric field in the biological tissue will be determined by σ and two parameters of ε.As electric field intensity is E, and current density is J, and space charge density is q, and then following formula is set up
div（εE）＝q （1）
From above-mentioned two formulas, do not change in time as ε, then have
For alternating electric field, as be expressed as E=E
0Cos(ω t+ φ), following formula can be handled with plural number, then has
As σ+i ω ε is expressed as complex permittivity
Then (4) formula also can be written as
Because ε and σ and coordinate are irrelevant, therefore have
Or be expressed as
(7) be the Laplace's equation formula.Therefore the electric field in the biological tissue satisfies Laplace's equation.In the even biological tissue that ε and σ do not change with coordinate, ε in any case and the combination of σ are always the distribution of electric field is identical like this.Therefore the equivalence of the electric field in the biological tissue can be analyzed for general electrostatic field problem.
Adopt surface method to calculate two dimension or three-dimensional planar or axisymmetric electrostatic field universal program (SCMO2) electric field in the tissue between two electrodes in the six-ring electrode scheme is calculated, the result of analytical calculation as shown in Figure 7.Because of being axially symmetric field, only calculate to cross section half carry out.
As seen from Figure 7, really there being the be parallel to each other zone of (in certain depth of parallelism scope) of an equipotential line on this square section between the galvanic electrode, also be the electric current distribution parallel equidistant.Therefore on this zone, voltage electrode is set, writes down its current potential, can realize biological tissue's dielectric property is measured and data computation exactly.
If the extrinsic motivated electric current is
, two distance between electrodes also are that thickness of tissue is D, are the r place at radius, have in the zone that equipotential line as shown in Figure 7 is parallel to each other
In uniform biological tissue, current density
With electric field intensity
The pass be
So, the voltage between two voltage electrodes is
The admittance that can be got ring-type tissue between two voltage electrodes by following formula is
Therefore can get the electrical conductivity σ and the DIELECTRIC CONSTANT of biological tissue
Wherein D is a thickness of tissue, r
1, r
2Be the radius of two voltage electrode rings, ω is the angular frequency of excitation.
As long as record the thickness and the voltage of biological tissue, the amplitude of electric current and phase differential can be obtained the electrical conductivity and the specific inductive capacity of biological tissue easily by following formula.
The present invention measures the six-ring electrode device of biological dielectric character and is made up of electrode system and measuring system.
Electrode system is except six-ring electrode, also have the contact pressure governor motion (12) of temperature sensor (9), digital temperature display (13), temperature-control circuit (14), electrode and tissue and measure graduated scale (11), the thermostat (8) of tissue thickness, as shown in Figure 7.Temperature sensor (9) is a thermistor, contacts with tested tissue; Digital temperature display (13) is made of three and half A/D converters and three and half LCD; Temperature-control circuit (14) is made of prewired circuit, comparison amplifier, driver and controllable silicon, resistive heating device, and wherein prewired circuit is made of the potentiometer bleeder circuit, and comparison amplifier is made of bipolar high input impedance integrated amplifier F347; The contact pressure governor motion (12) of electrode and tissue is a right angle support, support is suitable for reading to be inlaid with two-layer dividing plate towards horizontal direction, it is the aperture of 10mm that there is a diameter in two dividing plate central authorities, there is a solid pole to pass through in the aperture, solid pole one end heads on potential electrode (being positioned at above the guard electrode), screw thread is carved with in the stage casing of solid pole, last cover one spring and nut place between two dividing plates, the scale of size is carved with for measuring the graduated scale (11) of tissue thickness in solid pole upper end, and guard electrode is fixed on the support base plate; Thermostat (8) is a WC/09-05 type thermostat.
Measuring system comprises mimic channel and digital control circuit two large divisions.
Artificial circuit part comprises program control sine wave signal generator (15), constant-current source circuit (1), broadband voltage amplifier (16), amplitude discriminator (18), phase detector (19), wideband current amplifier (17), direct current amplifier, A/D converter (20), D/A (22).
Program control sine wave signal generator (15) mainly is made of the accurate function generator 5G8038 of monolithic; Constant-current source circuit (1) is made of two integrated transporting dischargings, is actually a current/charge-voltage convertor; Broadband voltage amplifier (16) adopts bipolar MOS high input impedance operational amplifier F3140; Wideband current amplifier (7) is made of two operational amplifiers, and previous stage is finished the current-voltage conversion, and the back level is as amplifying; Amplitude discriminator is made of accurate half-wave rectifying circuit and second-order low-pass filter; Phase detector is by two limiting amplifiers, and phase comparator and low-pass filter constitute.
Digital control circuit part mainly by the Z-80 one board microcomputer, it measures system software (monitoring master routine, measurement and data processing subroutine, output subroutine and floating-point operation subroutine) as a result, the printer formation of computing.
Whole surveying work process of the present invention is as follows:
After tissue exsomatizes, cut out a sheet tissue, place between the potential electrode and guard electrode of the six-ring electrode on the contact point pressure governor motion support of electrode and tissue, regulate the nut on the solid pole, electrode is contacted well with tested tissue.Then, be placed in the thermostat propping up, at this moment, temperature sensor is converted to electric weight with tested tissue temperature, is input to temperature indicator and temperature-control circuit part.Show the tested tissue temperature by temperature indicator, the temperature-control circuit part is with the temperature of the temperature variation FEEDBACK CONTROL constant temperature device of tested tissue, to guarantee the constant of tissue temperature.Check size scale on the solid pole, learn the thickness D of tested tissue, its thickness D input computing machine, by the time after the temperature of tested tissue temperature for setting, click the command key on the computing machine.Under the control of computing machine, it be that this voltage converts sinusoidal current to by constant-current source circuit, as the exciting current of biological tissue's dielectric property measurement from 1 hertz of sinusoidal voltage in 100 kilohertz range that program control sine wave signal generator produces frequency.Exciting current acts on tested tissue by the galvanic electrode in the six-ring electrode.Broadband voltage/current amplifier amplifies the current potential and the current signal of electrode detection, by the amplitude of amplitude discriminator and phase detector output voltage signal and both phase differential, by direct current amplifier these signals are amplified to the desired DC level of A/D converter, convert digital signal to by A/D converter again and be input to computing machine.Computing machine calculates the electrical conductivity and the specific inductive capacity of tested tissue according to 13 and 14 formulas, by its result of printer output.
Six-ring electrode is rubbed potential electrode and guard electrode and is one; controlled the distribution of electric current in the tissue well; make and measure in the tissue of current concentration between potential electrode; make between two electrodes, electric current is distributed with rule in the tissue under the voltage electrode; square section current density line is an equidistant parallel line; be regular radiation-like in radial current density, so just improved measuring accuracy.Can not disperse in the extraneous tissue of electrode disk owing to measure electric current, this just makes six-ring electrode technology can directly carry out the measurement of dielectric property to lamellar structure on life entity.And six-ring electrode only needs that when measuring a sheet is cut in biological tissue and places between potential electrode and the guard electrode.Therefore make the making of biological tissue's sample simple, convenient, reduced to organize isolated time, avoid cutting processing repeatedly, thereby reduced to make thus the measuring error that the normal physiological of biological tissue, biochemical state change and bring tested tissue.
Potential electrode and tissue temperature are shown electrode system and the size scale of control, tissue and contact pressure are regulated and combined, make the dielectric property of biological tissue is measured more easy, fast and accurately.
Measuring process is carried out under the control of computing machine fully, and it is short to have Measuring Time, and measuring accuracy is than characteristics such as height.
The invention will be further described below in conjunction with accompanying drawing:
Fig. 1 is four utmost point measurement mechanism synoptic diagram, and wherein (1) is constant-current source circuit, and (2) are voltage measurement, and (3) are tested tissue, and (4) are galvanic electrode, and (5) are voltage electrode.
Fig. 2 is a four-probe measurement device utility structure synoptic diagram.
Fig. 3 is needle-like four electrode synoptic diagram.
Fig. 4 constitutes synoptic diagram for six-ring electrode of the present invention, and wherein (6) are potential electrode, and (7) are guard electrode.
Fig. 5 is a six-ring electrode of the present invention square section Electric Field Distribution synoptic diagram, and wherein one is the current density line, and one is equipotential line.
Fig. 6 is a six-ring electrode radial electric field distribution schematic diagram of the present invention, and wherein one is the current density line ,-be equipotential line.
Fig. 7 is the Electric Field Distribution numerical analysis result in the tissue between the electrode of the present invention.
Fig. 8 is electrode system principle of compositionality synoptic diagram among the present invention, wherein (8) are thermostat, (9) be temperature sensor, (11) be tissue thickness's graduated scale, (12) for electrode with organize the contact pressure governor motion, (13) be the digital temperature display, (14) are temperature-control circuit.
Fig. 9 is measuring system schematic block diagram among the present invention, wherein (15) are program control sine wave signal generator, (16) be the broadband voltage amplifier, (17) be the wideband current amplifier, (18) are amplitude discriminator, and (19) are phase detector, (20) be A/D converter, (22) be D/A, (21) are the Z-80 single board computer, and (23) are printer.
The present invention is except being used for the measurement of biological tissue's dielectric property, and the dielectric property that also can be used for the materials such as medicine, food service industry liquid, colloid is measured, might be as a kind of method for quickly detecting of medicine, food.
Claims (1)
1, a kind of six-ring electrode device of measuring biological dielectric character is made of electrode system and measuring system, it is characterized in that described electrode system comprises the electrode part, the graduated scale of pressure regulating mechanism and measurement sample thickness; Described electrode part is divided into six-ring electrode, comprise potential electrode and guard electrode, potential electrode is made of four metal rings on the insulation disk, outer shroud and interior ring are galvanic electrode, two rings between the inner and outer ring are voltage electrode, the midpoint of two voltage electrodes between the inner and outer ring distance, and guard electrode is made of two metal rings on another insulation disk, these two annulus also are galvanic electrode, and are identical with galvanic electrode diameter in the potential electrode; Sample places between potential electrode and the guard electrode, guarantees good contact the between electrode and the sample by described pressure regulating mechanism; The described graduated scale that the thickness of sample is used on the solid pole is measured.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 88100107 CN1010252B (en) | 1988-01-11 | 1988-01-11 | Six-ring electrode technology for measuring biological dielectric character |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 88100107 CN1010252B (en) | 1988-01-11 | 1988-01-11 | Six-ring electrode technology for measuring biological dielectric character |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1034272A CN1034272A (en) | 1989-07-26 |
| CN1010252B true CN1010252B (en) | 1990-10-31 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 88100107 Expired CN1010252B (en) | 1988-01-11 | 1988-01-11 | Six-ring electrode technology for measuring biological dielectric character |
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| CN (1) | CN1010252B (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103261880B (en) * | 2010-08-22 | 2015-05-06 | 恒鹏设备有限公司 | Electrode unit for use in a fryer and fryer comprising a said electrode unit |
| CN102090889B (en) * | 2011-01-21 | 2013-01-09 | 中山大学 | Concentric circle type metal body surface electrode for bioelectrical impedance detection technology and manufacturing method thereof |
| CN102928670B (en) * | 2012-10-30 | 2014-10-22 | 中国人民解放军第四军医大学 | Dielectric property measuring box for cylindrical in vitro biological tissues |
| DE102016118526A1 (en) * | 2016-09-29 | 2018-03-29 | Krohne Messtechnik Gmbh | Conductivity meter for measuring an electrical conductivity of a liquid medium |
| CN107374628B (en) * | 2017-07-13 | 2020-05-29 | 中国医学科学院生物医学工程研究所 | Minimally invasive biological tissue conductivity/dielectric constant measuring electrode and measuring method |
| CN109612921B (en) * | 2018-12-13 | 2021-08-31 | 国网山东省电力公司电力科学研究院 | Corrosion monitoring sensor and preparation method thereof |
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1988
- 1988-01-11 CN CN 88100107 patent/CN1010252B/en not_active Expired
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| Publication number | Publication date |
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| CN1034272A (en) | 1989-07-26 |
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