Dielectric Spectroscopy

Abstract

This dielectric spectrometry device includes a sensor unit (1) in which the following are formed on the same substrate: an antenna unit (110) having a coaxial line structure, with an end contacting a sample being an open end; an open unit (111) having a coaxial line structure, with an end contacting air being an open end; a short-circuit unit (112) having a coaxial line structure, with a center conductor and the ground conducting at the tip; a load unit (13) terminating a signal line; and switches (12, 14) selectively connecting any one of the antenna unit (110), the open unit (111), the short-circuit unit (112), and the load unit (13) to a port of a reflection measurement device (2).

Description

[Technical Field]

[0001] The present invention relates to a dielectric spectroscopic measuring device used for non-invasive component concentration measurement in humans or animals. [Background technology]

[0002] As the aging population continues, responding to adult diseases is becoming a major issue. Tests such as blood glucose levels require blood sampling, which places a heavy burden on patients. For this reason, non-invasive element concentration measuring devices that do not require blood sampling are attracting attention.

[0003] A device that uses dielectric spectroscopy has been proposed as a non-invasive device for measuring blood constituent concentrations. Dielectric spectroscopy involves irradiating electromagnetic waves into the skin, using the interaction between the blood constituent to be measured (e.g., glucose molecules) and water to absorb the electromagnetic waves, and then observing the amplitude and phase of the electromagnetic waves. However, because the interaction between glucose and electromagnetic waves is weak and there is a limit to the intensity of electromagnetic waves that can be safely irradiated to the living body, this method has not yet been sufficiently effective in measuring blood glucose levels in the living body.

[0004] An example of a conventional device is one that uses a coaxial probe that irradiates an electromagnetic wave in the microwave to millimeter wave band onto a measurement object (see Patent Document 1). Fig. 6 shows an example of the configuration of a constituent concentration measuring device that uses the coaxial probe disclosed in Patent Document 1. The constituent concentration measuring device is composed of a coaxial probe 100 whose end on the sample side is an open end, an electronic calibration module 101, and a vector network analyzer (hereinafter referred to as VNA) 102.

[0005] In the example of Figure 6, the concentration of a target component in a solution containing a mixture of a background component and a target component is measured. As described in Non-Patent Document 1, the configuration of Figure 6 is a common configuration for measuring complex permittivity, and the open-type coaxial probe 100 is suitable for measuring liquids. The VNA 102 calculates the complex permittivity from the reflected signal obtained by the coaxial probe 100, assuming an infinite boundary. Specifically, an electric field is applied to the sample from the coaxial probe 100. The VNA 102 measures the reflection coefficient and phase of the wave reflected by the sample in the frequency domain to calculate the complex permittivity. This method is called the frequency-domain reflectometry.

[0006] Another method involves applying a pulsed electric field to a sample and determining the complex permittivity from the time change in the waveform of the reflected wave reflected by the sample. When a pulsed electric field is applied, the transmission coefficient may be measured instead of the reflection coefficient. The method of determining the complex permittivity from the time change in the waveform of the reflected wave is called time domain reflectometry or time domain transmittance measurement. In the frequency domain reflectometry, the frequency of the applied electric field is swept to obtain the reflection coefficient and phase spectrum. From the measured spectrum, the complex permittivity can be calculated as follows:

[0007]

number

[0008] where ε * is the dielectric constant of the sample, ε i * (i=A, B, C) is the dielectric constant of the standard sample. * is the complex reflection coefficient, and the reflection coefficient obtained by measurement is Γ i , the phase is φ i Then, it is expressed by the following equation (2).

[0009]

number

[0010] ρ icorrespond to the measurement results of the standard samples, and ρ * is the measurement result of the sample. In a typical measurement, the state in which the coaxial probe 100 is placed in the air (open state) is taken as standard sample A, the state in which the coaxial probe 100 is short-circuited (short state) is taken as standard sample B, and a standard solution sample with a known dielectric constant is taken as standard sample C. When the coaxial probe 100 is short-circuited, it must be terminated so that inductance does not occur at the end.

[0011] As described above, the constituent concentration measuring device calculates the dielectric relaxation spectrum from the amplitude and phase of the signal corresponding to the frequency of the observed electromagnetic wave. Generally, the dielectric relaxation spectrum is expressed as a linear combination of relaxation curves based on the Cole-Cole equation, and the complex dielectric constant is calculated. In measuring biological constituents, for example, there is a correlation between the amount of blood constituents, such as glucose or cholesterol, contained in the blood and the complex dielectric constant, so an electrical signal (amplitude, phase) corresponding to changes in the amount of the blood constituent is obtained. A calibration model is constructed by measuring the correlation between the change in complex dielectric constant and the constituent concentration in advance, and the constituent concentration is calibrated from the change in the measured dielectric relaxation spectrum. It is also possible to calibrate the constituent concentration from the change in reflection coefficient by measuring the correlation between the change in reflection coefficient and the constituent concentration in advance.

[0012] In reflection measurement instruments that calculate the reflection coefficient by measuring incident and reflected voltages, it is known that drift errors in the reflection coefficient occur due to fluctuations in environmental temperature and vibrations and stresses applied to the measurement cable. Generally, as shown in Figure 6, an electronic calibration module 101 is connected to a coaxial probe 100, and the sequential calibration function of the electronic calibration module 101 is used to automatically recalibrate the fluctuations that occur in the VNA 102 and the measurement cable after each measurement. This sequential calibration function can reduce cable instability and system drift errors (see Patent Document 2).

[0013] However, with the conventional configuration, although it is possible to calibrate system variation factors from the VNA 102 to the electronic calibration module 101, it has been difficult to calibrate the drift error caused by the coaxial probe 100. Therefore, in order to maintain measurement accuracy, it is necessary to measure the standard sample multiple times at the end face of the coaxial probe 100, which poses the problem of not being able to obtain measurement repeatability or measurement accuracy due to changes in sample temperature or drying. [Prior art documents] [Patent documents]

[0014] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-69779 [Patent Document 2] Japanese Patent Application Publication No. 7-198767 [Non-patent literature]

[0015] [Non-Patent Document 1] Andrew P.Gregory,and Robert N.Clarke,“A Review of RF and Microwave Techniques for Dielectric Measurements on Polar Liquids”, IEEE Transactions on Dielectrics and Electrical Insulation,Vol.13,No.4,Aug.2006 Summary of the Invention [Problem to be solved by the invention]

[0016] The present invention has been made to solve the above-mentioned problems, and has an object to provide a dielectric spectroscopy measuring device that can reduce drift errors caused by a coaxial probe. [Means for solving the problem]

[0017] The dielectric spectroscopy measurement apparatus of the present invention comprises a sensor unit and a calibration unit configured to calibrate a reflection measurement instrument connected to the sensor unit, wherein the sensor unit comprises an antenna unit with a coaxial line structure having an open end at the end that comes into contact with a sample of interest, an open unit with a coaxial line structure having an open end at the end that comes into contact with air, a short unit with a coaxial line structure in which a center conductor is electrically connected to a ground at the tip, a load unit configured to terminate a signal line, and a switch configured to selectively connect any one of the antenna unit, the open unit, the short unit, and the load unit to a port of the reflection measurement instrument by controlling the switch to sequentially connect the short unit, the open unit, and the load unit to the port of the reflection measurement instrument, thereby performing reflection measurements for each, and calibrating the reflection measurement instrument based on the results of the reflection measurements. [Effects of the Invention]

[0018] According to the present invention, the antenna section, short section, open section, and load section are integrated on the same substrate, thereby reducing drift errors caused by coaxial probes. Furthermore, the present invention also makes it easy to calibrate the reflectometer as needed. As a result, the present invention enables wideband data acquisition while reducing drift errors caused by environmental fluctuations and changes in the sample state over time. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a block diagram showing the configuration of a dielectric spectroscopy measurement device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view of a sensor unit according to an embodiment of the present invention. [Figure 3] FIG. 3 is an exploded perspective view of a sensor unit according to an embodiment of the present invention. [Figure 4] FIG. 4 is a cross-sectional view showing another example of a sensor unit according to an embodiment of the present invention. [Figure 5]FIG. 5 is a block diagram showing an example of the configuration of a computer that realizes a reflection measuring instrument according to an embodiment of the present invention. [Figure 6] FIG. 6 is a block diagram showing an example of the configuration of a conventional constituent concentration measuring device. DETAILED DESCRIPTION OF THE INVENTION

[0020] An embodiment of the present invention will be described below with reference to the drawings. In this embodiment, to address the above-mentioned problem, highly accurate dielectric spectroscopy measurement is performed while sequentially calibrating the drift error. Figure 1 shows the configuration of a dielectric spectroscopy measurement device according to this embodiment. The dielectric spectroscopy measurement device comprises a sensor unit 1 and a reflection measurement device 2. For example, a vector network analyzer (VNA) is used as the reflection measurement device.

[0021] The sensor section 1 includes a dielectric substrate 10, a coaxial probe 11, a switch 12, a load section 13, a switch 14, an RF connector 15, and control connectors 16 and 17.

[0022] 2 is a cross-sectional view of the sensor unit 1, and FIG. 3 is an exploded perspective view of the sensor unit 1. The coaxial probe 11, switches 12 and 14, load unit 13, RF connector 15, and control connectors 16 and 17 are mounted on a dielectric substrate 10. The coaxial probe 11 includes a plurality of coaxial probe sections, each of which includes at least one antenna section 110, an open section 111, and a short section 112.

[0023] In microwave and millimeter-wave radio frequency (RF) technology, a known configuration is to integrate integrated circuits (ICs), antennas, and sensors on the same dielectric substrate to reduce insertion loss between the ICs and antennas or sensors, and multilayer wiring boards are used to optimize the layout of signal and power lines and reduce the board area. Vias and through-holes that penetrate the board are used as structures to transmit RF signals between layers of multilayer wiring boards.

[0024] Japanese Patent No. 6771372 discloses a pseudo-coaxial line structure in which a plurality of ground vias are provided around a high-frequency signal via formed vertically penetrating from the top to the bottom layer of a multilayer wiring board in which conductor layers and insulator layers are alternately stacked. In this embodiment, this pseudo-coaxial line structure is adopted to form the antenna section 110, the open section 111, and the short section 112.

[0025] The antenna section 110 has a pseudo-coaxial line structure in which the end on the side in contact with the sample (upper side in FIG. 2) is an open end. Specifically, in the antenna section 110, a land 1100 made of a conductor is formed on the upper surface of the uppermost insulator layer 22 of the multilayer wiring substrate 21, and a land 1101 made of a conductor is formed on the lower surface of the lowermost insulator layer 25. The land 1100 and the land 1101 are connected by a high-frequency signal via 1102, which is a conductor that vertically penetrates each of the insulator layers 22 to 25 along the stacking direction of the conductor layers 26 to 30.

[0026] A conductor layer 26 serving as a ground conductor is formed in the same layer as the land 1100 but in an area outside the land 1100. The land 1100 and the conductor layer 26 are separated by a conductor removal area 1103 that is circular in plan view and has no conductor. Similarly, a conductor layer 30 serving as a ground conductor is formed in the same layer as the land 1101 but in an area outside the land 1101. The land 1101 and the conductor layer 30 are separated by a conductor removal area 1104 that is circular in plan view and has no conductor. In the present invention, the plan view is defined as the view of the sensor unit 1 from above (the sample side).

[0027] A plurality of conductor layers 27-29 serving as ground conductors are formed inside the multilayer wiring board 21. In the antenna section 110, the layer on which the conductor layers 27-29 are formed has a conductor removal area 1105 that is circular in plan view and is an area without conductor and filled with dielectric. A high-frequency signal via 1102 passes through the center of the conductor removal areas 1103-1105. In the antenna section 110, the conductor layers 26-30 are electrically connected by a through via (through hole) 1106.

[0028] A quasi-coaxial line is formed by the insulator layers 22-25, the high-frequency signal via 1102 that penetrates the insulator layers 22-25 vertically, the conductor layers 26-30 around the high-frequency signal via 1102, and the through via 1106 that connects the conductor layers 26-30. As shown in Fig. 3, the high-frequency signal via 1102 and the conductor removal areas 1103-1105 are circular, and the impedance of the quasi-coaxial line can be designed according to the sample to be measured by the diameter of the high-frequency signal via 1102, the diameters of the conductor removal areas 1103-1105 that surround it, and the dielectric constant of the dielectric of the insulator layers.

[0029] Next, the open portion 111 has a pseudo-coaxial line structure in which the end on the side in contact with air (upper side in FIG. 2) is an open end. In the open portion 111, an opening 1110 (recess) which is a removed area having a circular shape in a plan view is formed in the uppermost conductor layer 26 and insulator layer 22 of the multilayer wiring board 21 so that the lower-layer insulator layer 23, conductor layer 27, and high-frequency signal via 1112 are exposed to the air. A land 1111 made of a conductor is formed on the lower surface of the lowermost insulator layer 25. The high-frequency signal via 1112, which is a conductor that vertically penetrates each of the insulator layers 23 to 25 along the stacking direction of the conductor layers 26 to 30, is formed so as to be connected to the land 1111. Note that the shape of the opening 1110 does not have to be circular as long as the lower-layer insulator layer 23, conductor layer 27, and high-frequency signal via 1112 are exposed to the air.

[0030] The land 1101 and the conductor layer 30 are separated by a conductor removal area 1113 that is circular in plan view and has no conductor. The high-frequency signal via 1112 and the conductor layer 27 are separated by a conductor removal area 1114 that is circular in plan view and has no conductor. In the open portion 111, the layer on which the conductor layers 28 and 29 are formed has a conductor removal area 1115 that is circular in plan view and has no conductor and is filled with an insulator (dielectric). The high-frequency signal via 1112 passes through the centers of the conductor removal areas 1113 to 1115. In the open portion 111, the conductor layers 27 to 30 are electrically connected by through vias 1116.

[0031] The insulating layers 23 to 25, the high-frequency signal via 1112 that vertically passes through the insulating layers 23 to 25, the conductor layers 27 to 30 around the high-frequency signal via 1112, and the through via 1116 that connects the conductor layers 27 to 30 form a pseudo-coaxial line. The incident signal is almost totally reflected in phase in the open portion 111. The opening portion 1110 may be provided with a shielding cap to prevent water, dust, etc. from entering from the outside.

[0032] Next, the short-circuit portion 112 has a pseudo-coaxial line structure in which the center conductor (high-frequency signal via) and ground are electrically connected at the tip. Specifically, in the short-circuit portion 112, a land 1120 made of a conductor is formed on the lower surface of the lowest insulating layer 25. The conductor layer 26 and the land 1120 are connected by a high-frequency signal via 1121, which is a conductor that vertically penetrates the insulating layers 22 to 25 along the stacking direction of the conductor layers 26 to 30.

[0033] The land 1120 and the conductor layer 30 are separated by a conductor-free area 1122 that is circular in plan view and has no conductor. In the short section 112, the layer on which the conductor layers 27 to 29 are formed has a conductor-free area 1123 that is circular in plan view and is an area filled with an insulator (dielectric). The high-frequency signal via 1121 passes through the centers of the conductor-free areas 1122 and 1123. In the short section 112, the conductor layers 26 to 30 are electrically connected by through vias 1124.

[0034] The insulating layers 22 to 25, the high-frequency signal via 1121 that passes vertically through the insulating layers 22 to 25, the conductor layers 26 to 30 around the high-frequency signal via 1121, and the through via 1124 that connects the conductor layers 26 to 30 form a pseudo-coaxial line. At the short section 112, the phase of the incident signal is inverted and the signal is almost totally reflected.

[0035] The coaxial probe 11 formed on the multilayer wiring board 21 as described above is mounted on the dielectric substrate 10. On the top surface of the dielectric substrate 10, signal lines 40 to 42 made of conductors, pads 43 to 45 made of conductors integrally formed with the signal lines 40 to 42, and a conductor layer 46 serving as a ground conductor are formed.

[0036] The signal lines 40-42 are separated from the conductor layer 46 by conductor-free areas 47-49, respectively. The pads 43-45 are separated from the conductor layer 46 by conductor-free areas 50-52, respectively, which are circular in plan view and have no conductor. A conductor layer 53, which serves as a ground conductor, is formed on the lower surface of the dielectric substrate 10.

[0037] The land 1101 and the pad 43, the land 1111 and the pad 44, the land 1120 and the pad 45, and the conductor layer 30 and the conductor layer 46 are connected by solder 54. In this way, the coaxial probe 11 is mounted on the dielectric substrate 10. The solder 54 may be ball-shaped.

[0038] The load section 13 formed on the dielectric substrate 10 is composed of a resistor 132 formed between a signal line 130 and a ground conductor 131, and terminates the signal line 130. The smaller the reflection from the load section 13, the better. Therefore, the resistance value of the resistor 132 is selected to match the impedance of the signal line 130.

[0039] Furthermore, switches 12 and 14, an RF connector 15, and control connectors 16 and 17 are mounted on the dielectric substrate 10. A signal line 40 connected to the antenna section 110, a signal line 41 connected to the open section 111, and a signal line 42 connected to the short section 112 are each connected to a selection terminal of the switch 12. This allows the switch 12 to select one of the antenna section 110, the open section 111, and the short section 112.

[0040] The signal line 130 of the load unit 13 is connected to one selection terminal of the switch 14. The other selection terminal of the switch 14 is connected to the input terminal of the switch 12. The input terminal of the switch 14 is connected to the RF connector 15. The control terminal of the switch 12 is connected to the control connector 16, and the control terminal of the switch 14 is connected to the control connector 17. Note that although an example in which two switches are used has been shown in this embodiment, a configuration in which one 1-input 4-output switch is used to select the antenna unit 110, the open unit 111, the short unit 112, and the load unit 13 may also be used. The control connector may also include a power line that supplies power to the switches 12 and 14.

[0041] In the present invention, it is not an essential requirement that the coaxial probe 11 be formed on the multilayer wiring board 21. In other words, the multilayer wiring board 21 and the dielectric board 10 may be the same board. In this case, there is no need to mount the different types of boards using solder or the like.

[0042] The one-port calibration method for VNAs using an open standard, a short standard, and a load standard as calibration standards is known as SOL calibration. In SOL calibration, the open standard, the short standard, and the load standard are connected to the output port of the VNA, and calibration data is measured. This calibration data can eliminate frequency response reflection tracking, directivity, and source match of the measurement system in reflection measurements using the output port to be calibrated (see JP 2007-285890 A).

[0043] In this embodiment, the calibration unit 200 of the reflection measurement instrument 2 outputs control signals to the switches 12 and 14 via the control connectors 16 and 17. This causes the calibration unit 200 to switch the switches 12 and 14 so that one of the short circuit 112, the open circuit 111, and the load circuit 13 is connected to a port of the reflection measurement instrument 2 via the RF connector 15. The calibration unit 200 sequentially connects the short circuit 112, the open circuit 111, and the load circuit 13 to the port of the reflection measurement instrument 2, and performs a reflection measurement for each. The calibration unit 200 then calculates calibration coefficients (S parameters of the error circuit present in the reflection measurement instrument 2) from the results of the reflection measurement. Calculating the calibration coefficients in this way makes it possible to calculate a reflection coefficient from which the measurement error of the reflection measurement instrument 2 has been removed. The method of calculating the calibration coefficients using SOL calibration is a well-known technique.

[0044] With the open end of antenna unit 110 in contact with the sample, measurement unit 201 of VNA2 switches 12 and 14 so that antenna unit 110 is connected to a port of VNA2 via RF connector 15. Measurement unit 201 applies an electric field to the sample from antenna unit 110 and calculates a reflection coefficient based on the amplitude and phase of the reflected voltage of the reflected wave reflected by the sample and the incident voltage measured by the VNA. At this time, the antenna unit measures the reflection coefficients of a standard sample in a shorted state, an open state, and a sample with a known dielectric constant in advance, and these reflection coefficients are used to calculate the complex dielectric constant of the sample. As described above, the complex dielectric constant may be calculated based on the time change in the waveform of the reflected wave.

[0045] 4, the coaxial probe 11 may include a standard sample section 114 in addition to the short section 112, the open section 111, and the load section 13. In this case, the switch 12 is configured to select any one of the antenna section 110, the open section 111, the short section 112, and the standard sample section 114.

[0046] In the standard sample portion 114, a conductor-free area 1140 that is circular in plan view and free of conductor is formed in the uppermost conductor layer 26 so as to expose the insulator layer 22. A land 1141 made of a conductor is formed on the lower surface of the lowermost insulator layer 25. A high-frequency signal via 1142, which is a conductor that vertically penetrates each of the insulator layers 23 to 25 along the stacking direction of the conductor layers 26 to 30, is formed so as to be connected to the land 1141.

[0047] The land 1141 and the conductor layer 30 are separated by a conductor-free, circular conductor removal area 1143 in plan view. In the standard sample part 114, the layer on which the conductor layers 27 to 29 are formed has a conductor removal area 1144 that is circular in plan view and is an area filled with an insulator (dielectric) and is free of conductors. The high-frequency signal via 1142 passes through the center of the conductor removal area 1144. In the standard sample part 114, the conductor layers 27 to 30 are electrically connected by through vias 1145.

[0048] On the top surface of the dielectric substrate 10, in addition to the signal lines 40 to 42, pads 43 to 45, and conductor layer 46, a pad 55 and a signal line (not shown) formed integrally with the pad 55 are formed. The land 1141 and the pad 55 are connected by solder 54. The signal line formed integrally with the pad 55 is connected to a selection terminal of the switch 12. This allows the switch 12 to select one of the antenna section 110, the open section 111, the short section 112, and the standard sample section 114.

[0049] When the standard sample portion 114 is used, the complex dielectric constant of the sample can be calculated from the reflection coefficients obtained from the antenna portion 110, the short portion 112, the open portion 111, and the standard sample portion 114, and the dielectric constant of the dielectric substrate measured in advance. Note that the standard sample portion 114 may have an opening similar to the open portion 111, and may be filled with a desired dielectric sample. The dielectric sample may be, for example, ceramics such as alumina, a liquid such as pure water, or a polymer such as polyimide.

[0050] As described above, in this embodiment, the antenna unit 110, short unit 112, open unit 111, and load unit 13 are integrated on the same substrate, thereby reducing drift errors caused by the coaxial probe. Being on the same substrate reduces the temperature difference between the antenna unit 110, short unit 112, and open unit 111, improving calibration accuracy. This embodiment also facilitates the calibration of the reflection measuring instrument 2 at any time. Calibration may be performed, for example, at regular intervals or according to user instructions. As a result, this embodiment enables wideband data acquisition while reducing drift errors caused by environmental fluctuations and changes in the sample state over time.

[0051] As the RF connector 15 that connects the sensor section 1 and the reflection measuring device 2, a high frequency connector suitable for the frequency to be used may be selected. The microstrip lines (signal lines and control lines) on the dielectric substrate 10 are made of a metal material with a conductor width of 100 to 300 μm and spacing of 50 μm, for example. Examples of metal materials include Au, Cu, and Al.

[0052] The multilayer wiring board 21 has a size of, for example, several centimeters by several centimeters square and a thickness of 10 to 500 μm. Materials for the insulator layers 22 to 25 (dielectrics) include FR4 (Flame Retardant Type 4), Megtron6 ​​(registered trademark), Teflon (registered trademark), LCP (Liquid Crystal Polymer), polyimide, LTCC (Low Temperature Co-fired Ceramics), etc.

[0053] In this embodiment, one antenna portion 110 is formed on the coaxial probe 11, but multiple antenna portions 110 may be formed, each having a different shape. This allows the antenna portion 110 to be selected depending on the target sample. The high-frequency signal via 1102 has a size of, for example, φ0.1 to 0.5 mm. The circular outer diameter of the antenna section 110 (the distance from the center of the high-frequency signal via to the surrounding conductive layer) is 0.2 to 2.0 mm. The land 1100 has a size of, for example, φ0.3 to 1.0 mm. Examples of metal materials include Au and Cu.

[0054] The calibration unit 200 and measurement unit 201 of the reflection measurement instrument 2 described in this embodiment can be realized by a computer equipped with a CPU (Central Processing Unit), a storage device, and an interface, and a program that controls these hardware resources. An example of the configuration of this computer is shown in Figure 5.

[0055] The computer includes a CPU 300, a storage device 301, a communication device 303, a transmitter 302, a receiver 304, a directional coupler 305, a power supply 306, a transformer 307, and a regulator 308. The transmitter 302 and the receiver 304 are connected to the sensor unit 1 via the directional coupler 305. Electromagnetic waves in the microwave band generated by the transmitter 302 are irradiated onto the measurement sample. A signal reflected from the measurement sample is input from the sensor unit 1 via the directional coupler 305 to the receiver 304, converted into a digital signal, and then read by the CPU 300. The CPU 300 outputs a control signal to the sensor unit 1 to control the switches 12 and 14, thereby sequentially reading the reflected signals from the antenna unit 110, the short unit 112, the open unit 111, and the load unit 13.

[0056] In such a computer, a program for implementing the dielectric spectroscopy measurement method of the present invention is stored in a storage device 301. A CPU 300 executes the control and arithmetic processing described in this embodiment in accordance with the program stored in the storage device 301. The reflection coefficient and dielectric constant obtained by the processing are transmitted to an external computer by a communication device 303 connected to the CPU 300. For example, a frequency synthesizer using a phase-locked loop is used as the transmitter 302. For example, a double-balanced mixer is used as the receiver 304. A circulator may be used instead of the directional coupler 305.

[0057] While the example in Fig. 5 shows an example of a direct conversion type transmission / reception configuration, a low IF (Intermediate Frequency) type transmission / reception configuration may be adopted by adding a transmitter with a slightly different transmission frequency. Power supply 306 supplies power to each device. For example, a DC-DC converter is used as transformer 307. Regulator 308 converts the input voltage from transformer 307 to a desired voltage. A linear regulator that can operate even with a low input / output potential difference is used as regulator 308. A lithium-ion battery or the like is used as power supply 306. [Industrial Applicability]

[0058] The present invention can be applied to a dielectric spectroscopy measurement device that uses a coaxial probe. [Explanation of symbols]

[0059] 1...sensor section, 2...reflection measuring device, 10...dielectric substrate, 11...coaxial probe, 12, 14...switch, 13...load section, 15...RF connector, 16, 17...control connector, 21...multilayer wiring board, 22-25...insulator layer, 26-30, 46, 53...conductor layer, 40-42, 130...signal line, 43-45, 55...pad, 1100, 1101, 1111, 1120, 1141...land, 110...antenna section, 111...open section, 112...short section, 114...standard sample section, 200...calibration section, 201...measurement section, 1102, 1112, 1121, 1142...high frequency signal via, 1106, 1116, 1124, 1145...through via, 1110...opening.

Claims

1. a sensor device; a calibration unit configured to calibrate a reflectance measurement device connected to the sensor device, The sensor device includes: an antenna unit formed on a base substrate and including a first coaxial line structure having an open end at one end on the side that contacts the target sample; an open section formed on the base substrate and including a second coaxial line structure having an open end at one end on the air-contacting side; a short circuit portion including a third coaxial line structure formed on the base substrate and having a center conductor and a ground electrically connected to one end of the third coaxial line structure closer to the sample; a first signal line formed on the base substrate; a load section configured to terminate the first signal line; a switch configured to selectively connect any one of the antenna section, the open section, the short section, and the load section to a port of the reflection measurement device; the calibration unit controls the switch to sequentially connect the short unit, the open unit, and the load unit to ports of the reflection measuring instrument, causing the reflection measuring instrument to perform reflection measurements, and calibrating the reflection measuring instrument based on the results of the reflection measurements.

2. 2. The dielectric spectroscopy measuring apparatus according to claim 1, a measuring device that is provided in the reflection measuring instrument, connects the antenna unit to the port via the switch, applies an electric field from the antenna unit to the sample, and calculates the complex dielectric constant of the sample based on a reflected wave that is reflected by the sample and received by the antenna unit.

3. 2. The dielectric spectroscopy measuring apparatus according to claim 1, The antenna unit is a multilayer wiring board in which a plurality of insulating layers and a plurality of selectively formed conductor layers are alternately stacked; a land formed on the surface of the multilayer wiring board facing the sample; a high-frequency signal via that penetrates the multilayer wiring board along the stacking direction of the multilayer wiring board and has one end connected to the land; a second signal line formed on the base substrate and connecting the other end of the high-frequency signal via on the side opposite to the sample to the switch; and through vias formed in the multilayer wiring board and connecting the plurality of conductor layers to each other, A dielectric spectroscopy measuring device characterized in that the land and the surrounding conductive layers, and the high-frequency signal via and the surrounding conductive layers, are each separated by a circular area in a plan view that is free of conductors.

4. 2. The dielectric spectroscopy measuring apparatus according to claim 1, The open portion is a multilayer wiring board in which a plurality of insulating layers and a plurality of selectively formed conductor layers are alternately stacked; a high-frequency signal via that penetrates the multilayer wiring board along the stacking direction of the multilayer wiring board; a third signal line formed on the base substrate and connecting one end of the high-frequency signal via on the side opposite to the sample to the switch; and through vias formed in the multilayer wiring board and connecting the plurality of conductor layers to each other, the high-frequency signal via is separated from the surrounding conductor layers by a circular area in plan view where no conductors are present; the multilayer wiring board has an opening formed in its surface facing the sample, and in the opening, the surface of the insulator layer facing the sample of the multilayer wiring board, the other end of the high-frequency signal via, and a part of the conductor layer surrounding the surface are exposed to air.

5. 2. The dielectric spectroscopy measuring apparatus according to claim 1, The short portion is a multilayer wiring board in which a plurality of insulating layers and a plurality of selectively formed conductor layers are alternately stacked; a high-frequency signal via that penetrates the multilayer wiring board along the lamination direction of the multilayer wiring board and has one end connected to the conductor layer formed on the surface of the multilayer wiring board facing the sample; a fourth signal line formed on the base substrate and connecting the other end of the high-frequency signal via on the side opposite to the sample to the switch; and through vias formed in the multilayer wiring board and connecting the plurality of conductor layers to each other, The dielectric spectroscopy measurement device, wherein the high-frequency signal via and the surrounding conductive layers are separated by a circular area in a plan view that is free of conductors.

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