WO2022153490A1 - Procédé de mesure de constante diélectrique - Google Patents

Procédé de mesure de constante diélectrique Download PDF

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Publication number
WO2022153490A1
WO2022153490A1 PCT/JP2021/001303 JP2021001303W WO2022153490A1 WO 2022153490 A1 WO2022153490 A1 WO 2022153490A1 JP 2021001303 W JP2021001303 W JP 2021001303W WO 2022153490 A1 WO2022153490 A1 WO 2022153490A1
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Prior art keywords
admittance
measured
dielectric constant
measuring
face
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PCT/JP2021/001303
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English (en)
Japanese (ja)
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昌人 中村
卓郎 田島
倫子 瀬山
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日本電信電話株式会社
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Priority to PCT/JP2021/001303 priority Critical patent/WO2022153490A1/fr
Publication of WO2022153490A1 publication Critical patent/WO2022153490A1/fr

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N22/00—Investigating or analysing materials by the use of microwaves or radio waves, i.e. electromagnetic waves with a wavelength of one millimetre or more
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
    • G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
    • G01R27/26—Measuring inductance or capacitance; Measuring quality factor, e.g. by using the resonance method; Measuring loss factor; Measuring dielectric constants ; Measuring impedance or related variables

Definitions

  • the present invention relates to a method for measuring a dielectric constant.
  • electromagnetic waves in the microwave-millimeter wave band are less scattered in the living body than optical methods such as near-infrared light, and the energy of one photon is low.
  • a method using is proposed.
  • Non-Patent Document 1 there is a method using the resonance structure shown in Non-Patent Document 1.
  • a device having a high Q value such as an antenna or a resonator is brought into contact with the measurement sample, and the frequency characteristics around the resonance frequency are measured. Since the resonance frequency is determined by the complex permittivity around the device, the component concentration is estimated from the shift amount of the resonance frequency by predicting the correlation between the shift amount of the resonance frequency and the component concentration in advance.
  • the dielectric spectroscopy shown in Patent Document 1 As another method using electromagnetic waves in the microwave-millimeter wave band, the dielectric spectroscopy shown in Patent Document 1 has been proposed.
  • dielectric spectroscopy an electromagnetic wave is irradiated into the skin, the electromagnetic wave is absorbed according to the interaction between a blood component to be measured, for example, a glucose molecule and water, and the amplitude and phase of the electromagnetic wave are observed.
  • the dielectric relaxation spectrum is calculated from the amplitude and phase of the observed electromagnetic wave with respect to the frequency.
  • the dielectric relaxation spectrum is generally expressed as a linear combination of relaxation curves based on the Core-Cole equation, and the complex permittivity is calculated.
  • the complex permittivity has a correlation with the amount of blood components such as glucose and cholesterol contained in blood, and is measured as an electric signal (amplitude, phase) corresponding to the change.
  • a calibration model is constructed by measuring the correlation between the change in the complex permittivity and the component concentration in advance, and the component concentration is calibrated from the measured change in the dielectric relaxation spectrum. Regardless of which method is used, it is important to measure the change in permittivity in advance by wideband dielectric spectroscopy because the measurement sensitivity can be expected to improve by selecting a frequency band that has a strong correlation with the target component. Is.
  • the method using a coaxial probe as shown in Non-Patent Documents 2 and 3 is a sample in which water or the like is easily available for calibrating the measuring instrument.
  • a coaxial probe Open-end coaxial probe or Open-end coaxial line
  • measurement using a conventional coaxial probe is based on the premise that the substance to be measured has a sufficient thickness, and for thin-layer samples and multilayer materials, the thickness of the material and the dielectric constant of a part of the material are known. Otherwise, there is a problem that the dielectric constant of the layered material cannot be measured.
  • the uniformity according to the present invention is the step of calibrating the measuring device using the standard sample and the measured value of the admittance yi of the probe end face of the measuring device calculated based on the measurement result of the dielectric constant of the standard sample. And the theoretical value of the admitance y i of the probe end face when the object to be measured is the standard sample, and the error component of the theoretical value of the admitance y i with respect to the measured value of the admitance y i is calculated.
  • This is a method for measuring the dielectric constant which comprises a step of calculating the dielectric constant of the substance to be measured by substituting the measured value of the admittance ym corrected as the theoretical value of the admittance ym .
  • the present invention it is possible to provide a method for measuring the dielectric constant capable of accurately measuring the dielectric constant of a MUT having an arbitrary shape.
  • the admittance of the probe end face is calculated using the interface between the coaxial probe and the substance to be measured as the calibration end face using three types of calibration standards as in the conventional coaxial method. It is represented by an equivalent circuit model consisting of capacitance and radiation admittance.
  • the parasitic element component is identified in advance using the measurement result of the calibration standard, and the admittance using the parasitic element component is corrected so that the admittance is equivalent to the analytical formula. Perform an inverse problem analysis on the admittance measurements corrected using the admittance model formula for any single or layered material.
  • the complex permittivity of the MUT can be measured accurately even when measuring a layered material or when measuring a high frequency band such as a millimeter wave or a THz wave.
  • the dielectric constant analysis method has the following steps.
  • Step a Calibrate the measuring device with a standard sample.
  • Step b The measured value of the admittance yi of the probe end face of the measuring device calculated based on the measurement result of the dielectric constant of the standard sample, and the theoretical value of the admittance yi of the probe end face when the object to be measured is the standard sample. And, are used to calculate the error component of the theoretical value of admittance yi with respect to the measured value of admittance yi.
  • Step c The dielectric constant of the substance to be measured is measured with a measuring device.
  • Step d The measured value of the admittance ym of the probe end face of the measuring instrument is calculated based on the measurement result of the dielectric constant of the substance to be measured.
  • Step e The measured value of the admittance ym of the probe end face is corrected by using the error component.
  • Step f Substituting the measured value of admittance ym corrected as the theoretical value of admittance ym into a model formula expressing the relationship between the theoretical value of admittance ym and the permittivity of the substance to be measured, the dielectric constant of the substance to be measured. Calculate the rate.
  • FIG. 1 shows a schematic diagram of the dielectric constant measuring method according to the present embodiment.
  • the measuring instruments include a display that displays the calculation result of the permittivity, a calculator that calculates the permittivity from the measurement results obtained by the measuring instrument, and a measuring instrument for measuring high frequency characteristics.
  • a coaxial probe which is an interface for contacting the MUT.
  • the display may be, for example, a display such as a measuring instrument or a PC.
  • the arithmetic unit may be a device capable of digital data processing such as a PC and a microcomputer.
  • a device capable of measuring high-frequency S-parameters and impedance such as a vector network analyzer or an impedance analyzer, or an IC chip capable of measuring its reflection characteristics by transmitting and receiving high frequencies may be used.
  • a known measuring device may be used.
  • FIG. 2 show a schematic diagram when a general-purpose measuring instrument is used as a measuring instrument and when an IC for measurement is used.
  • the measuring instrument and the coaxial probe are connected using a high-frequency cable, a transmission line formed on a high-frequency substrate, and a high-frequency connector.
  • a coaxial line may be used for the high-frequency cable, and a microstrip line, a coplanar line, a coplanar strip, or the like may be used for the transmission line.
  • a coaxial type connector such as SMA, SMK, SMV, 1 mm connector, a push-on type connector such as SMP, SMPM, or the like may be used.
  • FIG. 8 is a flowchart of a method for measuring the dielectric constant in the conventional method.
  • calibration is generally performed to eliminate the influence of high frequency characteristics such as cables and connectors.
  • the calibration end face becomes the AA'plane in FIG.
  • the relationship between the linear mapping between the reflectance coefficient ⁇ and admittance y when air, metal (metal for shorting), water and MUT used as standard samples is installed is expressed by the following equations (1) and (2). expressed.
  • the subscripts 1 to 3 correspond to the standard sample, and m corresponds to the MUT.
  • the equivalent circuit of admittance on the end face of the coaxial probe, that is, the BB'plane of FIG. 2 is represented by FIG. 8 (b-2).
  • C 0 is a capacitance component that spreads from the probe end face into the vacuum in the vacuum.
  • G 0 is the radiation conductance from the coaxial probe end face to the vacuum.
  • the relational expression of Eq. (3) is derived by regarding the element components other than the capacitance component and the radiation conductance as minute dipoles.
  • the radiation admittance G of the antenna of the medium having a dielectric constant ⁇ has the relation of the equation (4). From equations (3) and (4), a proportional relationship is derived from G 0 and ⁇ to the 2.5th power of the second term on the right side of equation (2).
  • s and w refer to calibration standard air, metal and water.
  • the permittivity is calculated from the ratio of the equivalent circuit assuming that the MUT is a uniform dielectric material. Therefore, when measuring a material such as a layered material whose dielectric constant distribution in the depth direction is not uniform, Since the effective permittivity up to the penetration depth of the probe is measured, the measurement result may differ depending on the measurement probe. For the same reason, even when the thickness of the MUT is less than or equal to the penetration depth of the probe, the dielectric constant of the mechanism for fixing the material such as the microchannel and the sample setting table may affect the measurement result. In addition, in the conventional method, the radiated electromagnetic field from the end face of the coaxial probe is ignored as sufficiently small, or is represented by a model approximated as a minute dipole.
  • the measurement accuracy may decrease in the frequency band above the GHz band. Further, as the measurement frequency becomes higher, the influence of the radiation conductance of the coaxial probe increases, which may cause an error factor used in the approximation of the conventional method.
  • FIG. 3 shows a flowchart of the dielectric spectroscopy method of the present embodiment.
  • calibration is performed by the same method as the conventional method.
  • the calibration of FIG. 3 is step a.
  • the step of calculating the correction element parameter of FIG. 3 is step b.
  • the admittance theoretical formula of the coaxial probe end face at the time of MUT installation is constructed with the variable as the permittivity of the MUT, and the dielectric constant of the MUT is analyzed so as to satisfy the measured value. Is calculated.
  • the theoretical formula of admittance is the mathematical expression of the admittance of the coaxial probe.
  • the integral-admittance model shown in the formula (9) may be used.
  • the step of measuring the reflectance coefficient of the MUT in FIG. 3 is step c.
  • the calculation of the admittance Ymeas in FIG. 3 is the step d.
  • ⁇ c is the permittivity of the insulator of the coaxial line
  • km is the number of waves when propagating the MUT at the measurement frequency
  • ⁇ m and ⁇ m are the permittivity of the MUT and the propagation constant of the electromagnetic wave when propagating the MUT
  • J 0 (x). ) Is a 0th order Vessel function.
  • the variable ⁇ is a variable generated by the Hankel transform.
  • the theoretical formula of admittance The mathematical expression of admittance of the coaxial probe may use a Transmission line model or the like in which the distance between the end face of the coaxial probe and the MUT is expressed by the coupling of propagation constants.
  • the correction of the influence based on the admittance model of FIG. 3 is step e.
  • the electromagnetic wave on the coaxial end face is composed of a reflected wave returning from the MUT to the measuring instrument and a radiated wave radiated into space when the coaxial probe is regarded as a minute antenna. Therefore, in the present embodiment, the admittance model of the coaxial probe is represented by the equivalent circuit shown in FIG. In FIG. 4, both C fcal and C f indicate the fringe capacitance of the electric field generated in the coaxial probe internal insulator.
  • C fcal indicates the capacitance component deembed by the probe end face according to the equation (5) or (8).
  • C 0 indicates the capacitance component extending from the probe end face into the vacuum in vacuum, and Yant indicates radiative admittance.
  • the radiated admittance is modeled as the radiated conductance of a minute dipole as shown in FIG. 8 (b-2).
  • the radiated admittance is expressed by using a series resonance or a parallel resonance circuit.
  • circuit elements may be added to model the radiated admittance as a circuit having more complicated resonance characteristics.
  • the calibration used in Eq. (5) or (8) deembeds the error component assuming that the metal is a short circuit, the air is an open circuit, and the water is an arbitrary load. Therefore, the circuit components included in the calibration end face BB'in FIG. 2 are only C f and ⁇ C 0 in FIG. 4, and there is a possibility that a discrepancy with the circuit components of the theoretical model may occur.
  • the error between the theoretical formula of admittance of the coaxial probe end face and the measured value in the conventional method is the radiation term Yant. It is assumed that it is caused by.
  • the error component Yant ( ⁇ wc ) when measuring water having a dielectric constant ⁇ wc can be expressed by Eq. (11). ..
  • Y measured ( ⁇ wc ) is the admittance of the coaxial probe when MUT is water, which is calculated by using Eq. (5).
  • Yant ( ⁇ wc ) has the waveform shown in FIG. Therefore, Yant ( ⁇ wc ) can be expressed by, for example, an RLC series resonant circuit.
  • Yant ( ⁇ wc ) is the antenna radiation term
  • Yant ( ⁇ wc ) can be expressed as equation (13) using the radiation admittance Yant ( ⁇ 0 ) in vacuum.
  • the radiating element component removed by the deembed is extracted.
  • the model equation of the coaxial probe when the material having an effective dielectric constant ⁇ eff is MUT is the equation (14).
  • the admittance and the permittivity ⁇ r are measured at the time of MUT measurement, and the measured value Y measured ( ⁇ r ) of the admittance is corrected by using the equation (14) to reduce the error from the model equation.
  • the calculation of the complex permittivity by the inverse problem analysis of FIG. 3 is step f.
  • FIG. 7 shows a comparison between the measured values of admittance before and after the correction and the model formula. It can be seen that the error between the measured value and the model formula is reduced by the proposed method, and the admittance model can be corrected so as to match the model formula. Then, ⁇ r that satisfies Eq. (15) is calculated by inverse problem analysis. Y oriented is the admittance corrected by the equation (14), and Y model ( ⁇ r ) is, for example, the equation (9). If the MUT is not a uniform material and its shape is known, a model including the shape of the MUT may be used as the Y model . For example, when the MUT is a layered material composed of two layers, it is shown as in Eq. (16). Here, the subscripts 1 and 2 are the first layer and the second layer of the layered material, and the side in contact with the probe end face is the first layer. Further, the variable d1 indicates the layer thickness of the first layer.
  • the layer thickness d1 of the first layer and the permittivity ⁇ 2 of the second layer are known, they are used as constants, and if they are unknown, they are added as variables and the inverse problem analysis is performed. You may. Further, the theoretical formula Y model may be used as an analysis formula based on electromagnetism for the admittance of the coaxial probe end face at the time of MUT measurement for any shape of MUT such as a multilayer material. This makes it possible to analyze the inverse problem for any shape.
  • equations (9) and (16) are generally non-linear functions
  • the inverse problem represented by equation (15) is an optimization method represented by, for example, the simplex method, the steepest descent method, or particle swarm optimization. , May be calculated using a numerical calculation method such as a neural network. As described above, the influence of radiation admittance is suppressed, and highly accurate dielectric spectroscopy for MUTs of arbitrary shapes becomes possible.
  • the measured admittance is corrected by using the correction formula, and the permittivity is measured by the inverse problem analysis of the correction value and the theoretical model of admittance.
  • the influence of parasitic components is corrected for the admittance measurement value of the coaxial probe at the time of sample measurement, and the inverse problem analysis of the admittance model formula of a single or layered material based on the electromagnetic field theory is performed.
  • the complex permittivity of the substance to be measured (MUT: Material Under the Test) can be measured with higher accuracy.
  • the present invention since it can be applied to a permittivity measuring device for a solution existing in a human or an animal and a permittivity measuring device for a solution collected from a human or an animal, it has high industrial utility value.

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Abstract

La présente invention porte, selon un mode de réalisation, sur un procédé de mesure de constante diélectrique comprenant : une étape consistant à effectuer un étalonnage ; une étape consistant à calculer une composante d'erreur théorique d'une admittance yi, par rapport à la valeur réelle de l'admittance yi ; une étape consistant à mesurer, avec un dispositif de mesure, la constante diélectrique d'une substance qui est mesurée ; une étape consistant à calculer, sur la base du résultat de mesure pour la constante diélectrique de la substance qui est mesurée, la valeur réelle de l'admittance ym de la surface d'extrémité d'une sonde du dispositif de mesure ; une étape consistant à corriger la valeur réelle de l'admittance ym de la surface d'extrémité de la sonde en utilisant la composante d'erreur ; et une étape consistant à calculer la constante diélectrique de la substance qui est mesurée par substitution de la valeur réelle corrigée de l'admittance ym pour la valeur théorique de l'admittance ym dans une formule de modèle qui exprime la relation entre l'admittance théorique ym et la constante diélectrique de la substance qui est mesurée.
PCT/JP2021/001303 2021-01-15 2021-01-15 Procédé de mesure de constante diélectrique WO2022153490A1 (fr)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2024070653A1 (fr) * 2022-09-30 2024-04-04 ソニーセミコンダクタソリューションズ株式会社 Dispositif de mesure et procédé de mesure

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Publication number Priority date Publication date Assignee Title
US6472885B1 (en) * 2000-10-16 2002-10-29 Christopher Charles Green Method and apparatus for measuring and characterizing the frequency dependent electrical properties of dielectric materials
JP2007263625A (ja) * 2006-03-27 2007-10-11 Hokkaido Univ 複素誘電率測定装置および複素誘電率測定方法
US20100064820A1 (en) * 2006-09-08 2010-03-18 Pierre-Yves David Method and device for measuring a multiple-phase fluid flowing through a pipe
JP2011047856A (ja) * 2009-08-28 2011-03-10 Institute Of National Colleges Of Technology Japan 液体の誘電率測定装置及び測定方法

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6472885B1 (en) * 2000-10-16 2002-10-29 Christopher Charles Green Method and apparatus for measuring and characterizing the frequency dependent electrical properties of dielectric materials
JP2007263625A (ja) * 2006-03-27 2007-10-11 Hokkaido Univ 複素誘電率測定装置および複素誘電率測定方法
US20100064820A1 (en) * 2006-09-08 2010-03-18 Pierre-Yves David Method and device for measuring a multiple-phase fluid flowing through a pipe
JP2011047856A (ja) * 2009-08-28 2011-03-10 Institute Of National Colleges Of Technology Japan 液体の誘電率測定装置及び測定方法

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Title
JULRAT, SAKOL: "Open-ended coplanar waveguide sensor for dielectric permittivity measurement", PROCEEDINGS OF IEEE INSTRUMENTATION AND MEASUREMENT TECHNOLOGY CONFERENCE, 2018, pages 1 - 5, XP033374386, DOI: 10.1109/I2MTC.2018.8409843 *
MARTENS, H.C.F.: "Measurement of the complex dielectric constant down to helium temperatures. I. Reflection method from 1 MHz to 20 GHz using an open ended coaxial line", REVIEW OF SCIENTIFIC INSTRUMENTS, vol. 71, no. 2, 2000, pages 473 - 477, XP012038000, DOI: 10.1063/1.1150226 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2024070653A1 (fr) * 2022-09-30 2024-04-04 ソニーセミコンダクタソリューションズ株式会社 Dispositif de mesure et procédé de mesure

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