Measurement system, method for measuring substances, and sensor

Abstract

To provide a sensor for measuring the electrical properties and temperature of a material that has a simple configuration and small size, while reducing the adverse effects of noise on the measurement of the electrical properties of the material. [Solution] A dielectric layer 50 is arranged on one side of the first and second electrode layers 21 and 22, and a third electrode layer 60 is arranged on the other side. The third electrode layer 60 is made of a material having a temperature-dependent electrical resistivity and has a portion that overlaps with at least a part of the first and second electrode layers 21 and 22 in a plan view. The first measuring device 301 is for measuring a first value based on the impedance between the first and second electrode layers 21 and 22. The second measuring device 302 is for measuring a second value based on the electrical resistance of the third electrode layer 60. The switching circuit 200 is connected to the third electrode layer 60 and can switch its state depending on whether the first value measurement or the second value measurement is performed.

Description

[Technical Field]

[0001] The present invention relates to a measurement system, a method for measuring a substance, and a sensor, and more particularly to a sensor having a dielectric layer covering multiple electrode layers, a measurement system using the same, and a measurement method. [Background technology]

[0002] Various sensors are known for determining the electrical properties of materials. For example, International Publication No. 2023 / 149571 (Patent Document 1) discloses a sensor for liquids. This sensor has first and second detection electrodes covered by a protective layer made of an insulator. A liquid is brought into contact with the protective layer so as to face each of the first and second detection electrodes through this protective layer. In this state, the complex impedance between the first and second detection electrodes is measured. Based on the information obtained from this measurement, the conductivity of the liquid is determined.

[0003] Various sensors are known for determining the temperature of a substance. One typical sensing principle utilizes the property that the electrical resistance of a metal resistor increases in proportion to temperature. By measuring the value corresponding to this electrical resistance, the temperature can be detected. For example, the temperature sensor disclosed in Japanese Patent Application Publication No. 2021-156669 (Patent Document 2) has a meandering resistance pattern on a ceramic substrate as the resistor. For example, Japanese Patent Application Publication No. 2022-096341 (Patent Document 3) discloses a temperature detection circuit that measures a voltage value as the value corresponding to electrical resistance. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2023 / 149571 [Patent Document 2] Japanese Patent Publication No. 2021-156669 [Patent Document 3] Japanese Patent Publication No. 2022-096341 [Overview of the project] [Problems that the invention aims to solve]

[0005] The sensor disclosed in the above-mentioned International Publication No. 2023 / 149571 is a type of sensor for determining the electrical properties of a material. However, it may be necessary to know not only the electrical properties of a material but also its temperature. For example, when estimating the composition or degradation of a material based on its electrical properties, if the temperature dependence of the electrical properties cannot be ignored, considering the temperature at which the electrical properties were measured can improve the accuracy of the estimation. Furthermore, it may be necessary to know not only the temperature at a given point in time, but also the temperature history over a certain period. For example, if the material being measured is one that deteriorates particularly easily at higher ambient temperatures, information on the temperature history can be useful in evaluating the deterioration. Therefore, it is conceivable to combine a sensor for determining the electrical properties of a material with a sensor for determining its temperature. Depending on the combination, the size of the sensors may become excessively large.

[0006] Furthermore, according to the aforementioned International Publication No. 2023 / 149571, the impedance between the first electrode layer and the second electrode layer is measured, but noise can adversely affect this measurement. A simple way to reduce this adverse effect is to add a shielding electrode to shield against noise, in addition to the sensing electrode group. However, adding this shielding electrode complicates the sensor configuration. This complexity leads to disadvantages such as increased manufacturing costs for the sensor.

[0007] The present invention was made to solve the above-mentioned problems, and its objective is to provide a measurement system, a method for measuring a material, and a sensor that have a simple configuration and small size, while reducing the adverse effects of noise on the measurement of the electrical properties of a material. [Means for solving the problem]

[0008] Embodiment 1 is a measuring system for measuring the electrical properties and temperature of a substance in contact with a sensing surface, comprising a sensor, the sensor comprising an insulating layer, a first electrode layer and a second electrode layer disposed on the insulating layer and spaced apart from each other in a plan view perpendicular to the thickness direction, a dielectric layer having a surface as the sensing surface and disposed on one side of the first electrode layer and the second electrode layer and covering the first electrode layer and the second electrode layer, and disposed on the other side of the first electrode layer and the second electrode layer so as to be separated from the first electrode layer and the second electrode layer by the insulating layer, having a first end and a second end, and having a temperature-dependent electrical resistivity. The measuring system comprises a third electrode layer made of a material and having a portion that overlaps with at least a portion of the first electrode layer and the second electrode layer in a plan view, and further comprises a first measuring device for measuring a first value based on the impedance between the first electrode layer and the second electrode layer of the sensor, a second measuring device for measuring a second value based on the electrical resistance between the first end and the second end of the third electrode layer of the sensor, and a switching circuit connected to the first end of the third electrode layer of the sensor, the circuit state being switchable depending on whether the first value measurement or the second value measurement is performed.

[0009] Embodiment 2 is the measurement system according to Embodiment 1, wherein the switching circuit includes a first switch section and a second switch section, the first end of the third electrode layer of the sensor is connected to a power supply via the first switch section and to ground via the second switch section, and the measurement system further comprises a control section, the control section opens the first switch section and closes the second switch section when measuring the first value.

[0010] Aspect 3 is the measurement system according to Aspect 1, wherein the switching circuit includes a first switch section and a second switch section, a first end of the third electrode layer of the sensor is connected to a power supply via the first switch section and is connected to a ground via the second switch section, the measurement system further includes a control unit, and when measuring the second value, the control unit sets the first switch section to a closed state and the second switch section to an open state.

[0011] Aspect 4 is the measurement system according to Aspect 1, wherein the measurement system further includes a control unit, and when measuring the first value, the control unit sets the switching circuit to a state in which the first end and the second end of the third electrode layer are electrically short-circuited, and when measuring the second value, the control unit does not set the switching circuit to a state in which the first end and the second end of the third electrode layer are electrically short-circuited.

[0012] Aspect 5 is the measurement system according to any one of Aspects 2 to 4, wherein the control unit has a measurement value evaluation unit that determines an evaluation result regarding the substance based on both the first value and the second value.

[0013] Aspect 6 is the measurement system according to any one of Aspects 1 to 5, wherein the insulating layer covers the other side of the third electrode layer.

[0014] Embodiment 7 is a method for measuring a substance, comprising the steps of: a) bringing a substance that is liquid or semi-solid into contact with a sensing surface of a sensor, the sensor comprising: an insulating layer; a first electrode layer and a second electrode layer disposed on the insulating layer and spaced apart from each other in a plan view perpendicular to the thickness direction; a dielectric layer having a surface as the sensing surface, disposed on one side of the first electrode layer and the second electrode layer and covering the first electrode layer and the second electrode layer; and a third electrode layer disposed on the other side of the first electrode layer and the second electrode layer so as to be separated from the first electrode layer and the second electrode layer by the insulating layer, having a first end and a second end, made of a material having a temperature-dependent electrical resistivity, and having a portion that overlaps with at least a part of the first electrode layer and the second electrode layer in a plan view, the method comprising: b) measuring a first value based on the impedance between the first electrode layer and the second electrode layer of the sensor; and c) measuring a second value based on the electrical resistance between the first end and the second end of the third electrode layer of the sensor.

[0015] Embodiment 8 is a method for measuring a substance according to Embodiment 7, wherein a switching circuit is connected to the first end of the third electrode layer of the sensor, the switching circuit includes a first switch section and a second switch section, the first end of the third electrode layer of the sensor is connected to a power supply via the first switch section and to ground via the second switch section, and in b), the first switch section is in an open state and the second switch section is in a closed state.

[0016] Embodiment 9 is a method for measuring a substance according to Embodiment 7, wherein a switching circuit is connected to the first end of the third electrode layer of the sensor, the switching circuit includes a first switch section and a second switch section, the first end of the third electrode layer of the sensor is connected to a power supply via the first switch section and to ground via the second switch section, and in c), the first switch section is closed and the second switch section is open.

[0017] Embodiment 10 is a method for measuring a substance as described in Embodiment 7, wherein b) is performed while electrically short-circuiting the first end and the second end of the third electrode layer, and c) is performed without electrically short-circuiting the first end and the second end of the third electrode layer.

[0018] Embodiment 11 is a method for measuring a substance according to any one of Embodiments 7 to 10, further comprising the step of determining an evaluation result for the substance based on both the first value and the second value.

[0019] Embodiment 12 is a method for measuring a substance according to any one of Embodiments 7 to 11, wherein the substance is a liquid.

[0020] Embodiment 13 is a method for measuring a substance according to any one of Embodiments 7 to 12, wherein the substance is oil and the first value is capacitance.

[0021] Embodiment 14 is a sensor for measuring the electrical properties and temperature of a substance in contact with a detection surface, comprising: an insulating layer; an impedance detection unit composed of a first electrode layer and a second electrode layer disposed on the insulating layer and spaced apart from each other in a plan view perpendicular to the thickness direction; a dielectric layer having a surface as the detection surface, disposed on one side of the first electrode layer and the second electrode layer and covering the first electrode layer and the second electrode layer; and a temperature detection unit disposed on the other side of the first electrode layer and the second electrode layer so as to be separated from the first electrode layer and the second electrode layer by the insulating layer, and composed of a third electrode layer made of a material having a temperature-dependent electrical resistivity, with a portion overlapping at least a part of the first electrode layer and the second electrode layer in a plan view.

[0022] Embodiment 15 is the sensor according to Embodiment 14, wherein the first electrode layer and the second electrode layer constitute a pair of interlocking comb-tooth electrodes, and in a plan view, the pair of comb-tooth electrodes include a first line-and-space pattern, the third electrode layer includes a second line-and-space pattern, and the region in which the second line-and-space pattern is arranged encompasses the region in which the first line-and-space pattern is arranged.

[0023] Embodiment 16 is the sensor according to Embodiment 14 or 15, wherein, in a cross-sectional view, the distance between the sensing surface and the first electrode layer and the second electrode layer is smaller than the distance between the third electrode layer and the first electrode layer and the second electrode layer.

[0024] Embodiment 17 is a sensor for measuring electrical characteristics or temperature as described in any one of Embodiments 14 to 16, wherein the dielectric layer is made of a sintered body.

[0025] The phrase "measure electrical properties and temperature" in this specification does not mean that it is necessary to measure electrical properties and temperature simultaneously. [Effects of the Invention]

[0026] According to Embodiment 1, the measurement system has the function of measuring the electrical properties of a substance by measuring a first value based on the impedance between the first electrode layer and the second electrode layer of the sensor, and the function of measuring the temperature of a substance by measuring a second value based on the electrical resistance between the first end and the second end of the third electrode layer of the sensor. The third electrode layer has a portion that overlaps with at least a part of the first electrode layer and the second electrode layer in a plan view. This allows, firstly, to reduce the size of the sensor in a plan view compared to the case where the third electrode layer does not have such a portion. Secondly, when measuring the electrical properties of a substance, the third electrode layer can shield at least a part of the first electrode layer and the second electrode layer used for the measurement from noise. Therefore, the configuration of the sensor can be simplified compared to the case where a separate electrode layer for shielding is provided. From the above, it is possible to have a sensor for measuring the electrical properties and temperature of a substance with a simple configuration and small size, while reducing the adverse effects of noise on the measurement of the electrical properties of the substance.

[0027] According to embodiment 2, when measuring the first value, i.e., measuring the electrical properties of the material, the first switch is set to an open state and the second switch is set to a closed state, so that the potential of the first end of the third electrode layer is set to the ground potential. This further enhances the effect of the third electrode layer shielding at least a portion of the first and second electrode layers used for the measurement from noise.

[0028] According to embodiment 3, when measuring the second value, i.e., measuring the temperature of the substance, the first switch is closed and the second switch is opened, thereby applying a potential from the power source to the first end of the third electrode layer. This forms a voltage divider circuit, and by using this applied potential to measure the electrical resistance between the first and second ends of the third electrode layer, the temperature of the substance can be measured.

[0029] According to embodiment 4, when measuring the first value, i.e., measuring the electrical properties of the material, the first and second ends of the third electrode layer, which functions as a shielding electrode, are electrically short-circuited. This prevents noise from inducing a voltage between the first and second ends of the third electrode layer. Therefore, the shielding effect of the third electrode layer when measuring electrical properties can be further enhanced. On the other hand, when measuring the second value, i.e., measuring the temperature of the material, it is necessary to measure the electrical resistance between the first and second ends of the third electrode layer. In this case, the first and second ends of the third electrode layer are not electrically short-circuited. This prevents the short circuit from making it impossible to measure the electrical resistance between the first and second ends of the third electrode layer. From the above, it is possible to measure the temperature of the material based on the electrical resistance between the first and second ends of the third electrode layer, while further enhancing the shielding effect of the third electrode layer by short-circuiting the first and second ends when measuring electrical properties instead of the temperature of the material.

[0030] According to embodiment 5, the measurement value evaluation unit determines an evaluation result for a material based on both a first value corresponding to the electrical properties of the material and a second value corresponding to the temperature of the material. This allows the temperature of the material to be taken into consideration when determining any evaluation result related to the electrical properties of the material.

[0031] According to embodiment 6, the insulating layer covers the other side of the third electrode layer. This reduces the temperature difference between the insulating layer and the third electrode layer. Therefore, the accuracy of measuring the temperature of the material can be improved.

[0032] According to embodiment 7, the method for measuring a substance measures the electrical properties of the substance by measuring a first value based on the impedance between the first electrode layer and the second electrode layer of the sensor, and measures the temperature of the substance by measuring a second value based on the electrical resistance between the first end and the second end of the third electrode layer of the sensor. The third electrode layer has a portion that overlaps with at least a part of the first electrode layer and the second electrode layer in a plan view. This allows, firstly, to reduce the size of the sensor in a plan view compared to the case where the third electrode layer does not have such a portion. Secondly, when measuring the electrical properties of the substance, the third electrode layer can shield at least a part of the first electrode layer and the second electrode layer used for the measurement from noise. Therefore, the configuration of the sensor can be simplified compared to the case where a separate electrode layer for shielding is provided. From the above, it is possible to have a sensor for measuring the electrical properties and temperature of a substance with a simple configuration and small size, while reducing the adverse effects of noise on the measurement of the electrical properties of the substance.

[0033] According to embodiment 8, when measuring the first value, i.e., measuring the electrical properties of the material, the first switch is set to an open state and the second switch is set to a closed state, so that the potential of the first end of the third electrode layer is set to the ground potential. This further enhances the effect of the third electrode layer shielding at least a portion of the first and second electrode layers used for the measurement from noise.

[0034] According to embodiment 9, when measuring the second value, i.e., measuring the temperature of the substance, the first switch is closed and the second switch is open, thereby applying a potential from the power source to the first end of the third electrode layer. This forms a voltage divider circuit, and by using this applied potential to measure the electrical resistance between the first and second ends of the third electrode layer, the temperature of the substance can be measured.

[0035] According to embodiment 10, when measuring the first value, i.e., measuring the electrical properties of the material, the first and second ends of the third electrode layer, which functions as a shielding electrode, are electrically short-circuited. This prevents noise from inducing a voltage between the first and second ends of the third electrode layer. Therefore, the shielding effect of the third electrode layer when measuring electrical properties can be further enhanced. On the other hand, when measuring the second value, i.e., measuring the temperature of the material, it is necessary to measure the electrical resistance between the first and second ends of the third electrode layer. In this case, the first and second ends of the third electrode layer are not electrically short-circuited. This prevents the short circuit from making it impossible to measure the electrical resistance between the first and second ends of the third electrode layer. From the above, it is possible to measure the temperature of the material based on the electrical resistance between the first and second ends of the third electrode layer, while further enhancing the shielding effect of the third electrode layer by short-circuiting the first and second ends when measuring electrical properties instead of the temperature of the material.

[0036] According to embodiment 11, the evaluation result for a substance is determined based on both a first value corresponding to the electrical properties of the substance and a second value corresponding to the temperature of the substance. This allows the temperature of the substance to be taken into consideration when determining any evaluation result related to the electrical properties of the substance.

[0037] According to embodiment 12, the substance that comes into contact with the sensor's detection surface is a liquid. Since the liquid is fluid, it is difficult for a gap to form between the liquid, which is the substance to be measured, and the detection surface. Therefore, measurement errors caused by this gap can be reduced.

[0038] According to Embodiment 13, the liquid brought into contact with the sensing surface of the sensor is oil. Since oil generally has high electrical resistance, evaluating the properties of the oil solely based on differences in electrical resistance may result in insufficient accuracy. In contrast, in this embodiment, the dielectric constant of the oil can be considered, thereby enabling a more accurate evaluation of the oil's properties.

[0039] According to embodiment 14, the electrical properties of a material can be measured by measuring a value corresponding to the impedance between the first electrode layer and the second electrode layer of the sensor, and the temperature of the material can be measured by measuring a value corresponding to the electrical resistance between the first end and the second end of the third electrode layer of the sensor. The third electrode layer has a portion that overlaps with at least a part of the first electrode layer and the second electrode layer in a plan view. This allows, firstly, to reduce the size of the sensor in a plan view compared to the case where the third electrode layer does not have such a portion. Secondly, when measuring the electrical properties of a material, the third electrode layer can shield at least a part of the first electrode layer and the second electrode layer used for the measurement from noise. Therefore, the configuration of the sensor can be simplified compared to the case where a separate electrode layer for shielding is provided. From the above, it is possible to have a sensor for measuring the electrical properties and temperature of a material with a simple configuration and small size, while reducing the adverse effects of noise on the measurement of the electrical properties of the material.

[0040] According to embodiment 15, firstly, the first electrode layer and the second electrode layer constituting the impedance detection unit constitute a pair of comb-tooth electrodes, thereby enabling a reduction in the size of the sensor in plan view while ensuring the accuracy of the measurement of the electrical properties of the material by the impedance detection unit. Secondly, the third electrode layer constituting the temperature detection unit includes a second line-and-space pattern, making it easy to increase the total length of the third electrode layer. This enables a reduction in the size of the sensor in plan view while ensuring the accuracy of the measurement of the temperature of the material by the temperature detection unit. Thirdly, the region where the second line-and-space pattern is arranged encompasses the region where the first line-and-space pattern is arranged. This enhances the shielding effect of the third electrode layer including the second line-and-space pattern on the first electrode layer and the second electrode layer including the first line-and-space pattern. As a result, the size of the sensor can be further reduced, and the adverse effects of noise on the measurement of the electrical properties of the material can be further reduced.

[0041] According to embodiment 16, firstly, the distance between the detection surface and the first electrode layer and the second electrode layer is relatively small. Correspondingly, the thickness of the dielectric layer located in this distance is also small. The measurement value by the impedance detection unit is determined by the dielectric layer having a surface as the detection surface and the material in contact with the detection surface. As described above, the small thickness of the dielectric layer reduces the influence of the dielectric on the measurement value. This makes it possible to improve the measurement accuracy of the electrical properties of the material. Secondly, the distance between the third electrode layer and the first electrode layer and the second electrode layer is relatively large. This makes it easy to sufficiently separate the third electrode layer from the first electrode layer and the second electrode layer constituting the impedance detection unit. Therefore, when measurement is being performed by the impedance detection unit, it is suppressed that electric field lines extend to the third electrode layer instead of the first electrode layer and the second electrode layer constituting the impedance detection unit. This makes it possible to improve the measurement accuracy of the electrical properties of the material. As described above, the measurement accuracy of the electrical properties of the material can be improved.

[0042] According to embodiment 17, the dielectric layer is made of a sintered body. Compared to the case where the dielectric layer is made of a non-sintered body, it is easier to increase the manufacturing efficiency of the sensor. In particular, when the insulating layer is also a sintered body, forming the dielectric layer and the insulating layer as a single sintered body makes it less likely for defects to occur starting at the interface between them. As a result, properties such as chemical resistance and thermal shock resistance are improved. [Brief explanation of the drawing]

[0043] [Figure 1] This is a block diagram schematically showing the configuration of a measurement system in one embodiment. [Figure 2] This is a schematic front view showing the configuration of the sensors in the measurement system shown in Figure 1. [Figure 3] This is a schematic rear view showing the configuration of the sensors in the measurement system shown in Figure 1. [Figure 4] Figures 2 and 3 show a schematic cross-sectional view illustrating the sensor configuration along line IV-IV. [Figure 5]Figure 4 is a cross-sectional view schematically showing the sensor configuration along line VV. [Figure 6] This is a schematic cross-sectional view showing the sensor configuration along line VI-VI in Figure 4. [Figure 7] This is a block diagram schematically showing the functional configuration of the control unit of the measurement system in Figure 1. [Figure 8] This is a block diagram schematically showing the hardware configuration of the control unit of the measurement system shown in Figure 1. [Figure 9] This is a flowchart illustrating a method for measuring a substance in one embodiment. [Figure 10] Figure 9 is a schematic rear view showing the process of bringing the material into contact with the sensor's detection surface. [Figure 11] Figure 9 is a schematic partial cross-sectional view showing the process of bringing a material into contact with the sensor's detection surface. [Figure 12] Figure 9 is an equivalent circuit diagram that schematically shows the process of bringing a substance into contact with the sensor's detection surface. [Figure 13] Figure 9 is a schematic block diagram showing the process of measuring the first value based on impedance. [Figure 14] Figure 9 is a schematic block diagram showing the process of measuring the second value based on electrical resistance. [Modes for carrying out the invention]

[0044] Embodiments of the present invention will be described below based on the drawings. For the sake of understanding the relative directional relationships between the drawings, an XYZ Cartesian coordinate system is shown in some of the drawings. In relation to this XYZ Cartesian coordinate system, the "X direction," "Y direction," and "Z direction" are directions parallel to the X, Y, and Z axes, respectively. The "positive X direction" is parallel to the X direction and is indicated by an arrow in the drawings, while the "negative X direction" is parallel to the X direction and is opposite to the positive X direction. The "positive Y direction," "negative Y direction," "positive Z direction," and "negative Z direction" are defined similarly. "On the positive-X-direction side of ..." means the positive X direction from the element specified by "of ...," and "on the minus-X-direction side of ..." means the negative X direction from the element specified by "of ...." "The positive Y-direction side of...", "the negative Y-direction side of...", "the positive Z-direction side of...", and "the negative Z-direction side of..." are defined similarly. "On one side of..." means some specific direction from the element specified by "of...", and "on another side of..." means the direction opposite to that specific direction from the element specified by "of...". For example, "on one side of..." may mean "on the minus-Y-direction side of...", in which case "on another side of..." would mean "on the positive Y-direction side of...".

[0045] <Measurement System> Figure 1 is a schematic block diagram showing the configuration of the measurement system 901 in one embodiment. Figure 2 is a schematic front view showing the configuration of the sensor 101 in the measurement system 901 of Figure 1. Figure 3 is a schematic rear view showing the configuration of the sensor 101 in the measurement system 901 of Figure 1. Figure 4 is a schematic cross-sectional view showing the configuration of the sensor 101 along line IV-IV in Figures 2 and 3. Figure 5 is a schematic cross-sectional view showing the configuration of the sensor 101 along line VV in Figure 4. Figure 6 is a schematic cross-sectional view showing the configuration of the sensor 101 along line VI-VI in Figure 4.

[0046] The measurement system 901 (Figure 1) is for measuring the electrical properties and temperature of a substance in contact with the detection surface SF (Figure 4). The measurement system 901 includes a sensor 101, an impedance measuring device 301 (first measuring device), an electrical resistance measuring device 302 (second measuring device), and a switching circuit 200. In this embodiment, the measurement system 901 also includes a control unit 300.

[0047] Sensor 101 is for measuring the electrical properties and temperature of a substance in contact with the detection surface SF. Sensor 101 includes an insulating layer 10, a first electrode layer 21 and a second electrode layer 22 that constitute the impedance detection section DI, a dielectric layer 50, and a third electrode layer 60 that constitutes the temperature detection section DT.

[0048] The first electrode layer 21 and the second electrode layer 22 are arranged on one surface of the insulating layer 10 (the top surface in Figure 4) and are spaced apart from each other in a plan view perpendicular to the thickness direction. The minimum distance between the first electrode layer 21 and the second electrode layer 22 is, for example, 20 μm or more and 100 μm or less. The first electrode layer 21 and the second electrode layer 22 are preferably made of a high melting point metal that is resistant to oxidation, such as platinum, tungsten, or cobalt. The thickness of the first electrode layer 21 and the second electrode layer 22 is, for example, about 5 μm.

[0049] The dielectric layer 50 is located on one side of the first electrode layer 21 and the second electrode layer 22 (on the negative Y side from the first electrode layer 21 and the second electrode layer 22 in Figure 4), and covers the upper surfaces of the first electrode layer 21 and the second electrode layer 22 in Figure 4. The dielectric layer 50 has a surface that serves as a sensing surface SF. The dielectric layer 50 may be made of a ceramic insulator, and in particular may be made of a sintered body. A dielectric layer 50 made of a sintered body may be formed by forming a green sheet and firing it.

[0050] The thickness of the dielectric layer 50 is preferably 1 μm or more and 10 μm or less, more preferably 1 μm or more and 5 μm or less. The dielectric layer 50 may contain zirconia or alumina as its main component, and more specifically may consist of zirconia or alumina, preferably consisting of zirconia. Relative permittivity ε of the dielectric layer 50 D is, ε D It is preferable to satisfy ≥10. For example, by using zirconia, an ε of about 30 can be achieved. D Furthermore, by using alumina, an ε of about 10 can be obtained, and by using alumina, an ε of about 10 can be obtained. D This can be obtained. If the thickness of the dielectric layer 50 is d [μm], then ε D It is preferable that / d≧1 is satisfied. In the cross-sectional view (Figure 4), the distance H1 between the detection surface SF and the first electrode layer 21 and the second electrode layer 22 may be smaller than the distance H2 between the third electrode layer 60 and the first electrode layer 21 and the second electrode layer 22. Note that the distance H1 corresponds to the thickness d of the dielectric layer 50.

[0051] The third electrode layer 60 is positioned on the other side of the first electrode layer 21 and the second electrode layer 22 (in Figure 4, on the positive Y side from the first electrode layer 21 and the second electrode layer 22) so as to be separated from the first electrode layer 21 and the second electrode layer 22 by the insulating layer 10. In plan view, the third electrode layer 60 has a portion that overlaps at least a part of the first electrode layer 21 and the second electrode layer 22. The third electrode layer 60 has an end 61 (first end) and an end 62 (second end). The third electrode layer 60 is made of a material having a temperature-dependent electrical resistivity. This material may be platinum.

[0052] As shown in Figure 4, the insulating layer 10 covers one side of the third electrode layer 60 (the side in the negative Y direction from the third electrode layer 60 in Figure 4). In other words, the insulating layer 10 covers the upper surface of the third electrode layer 60 in Figure 4. Furthermore, the insulating layer 10 may cover the other side of the third electrode layer 60 (the side in the positive Y direction from the third electrode layer 60 in Figure 4). In other words, the insulating layer 10 may cover the lower surface of the third electrode layer 60 in Figure 4. The insulating layer 10 may be made of a ceramic insulator. The insulating layer 10 may be made of the same material as the dielectric layer 50. The thickness of the insulating layer 10 is, for example, about 1 mm.

[0053] To ensure a large capacitance between the first electrode layer 21 and the second electrode layer 22 within a small size in plan view, the first electrode layer 21 and the second electrode layer 22 may constitute a pair of interlocking comb-tooth electrodes. In this case, in plan view, the pair of comb-tooth electrodes include a line-and-space pattern RNa (first line-and-space pattern), and the third electrode layer 60 includes a line-and-space pattern RNb (second line-and-space pattern). The region where the line-and-space pattern RNb is located may encompass the region where the line-and-space pattern RNa is located. The line width of the line-and-space pattern RNa (the vertical dimension of each line in Figure 5) may be between 20 μm and 100 μm. The space width of the line-and-space pattern RNa (the vertical dimension of each space in Figure 5) may be between 20 μm and 100 μm. The line width of the line and space pattern RNb (the lateral dimension of each line in Figure 6) may be between 20 μm and 100 μm. The space width of the line and space pattern RNb (the lateral dimension of each space in Figure 6) may be between 20 μm and 100 μm.

[0054] In the following description, the direction of extension of each line in the line-and-space pattern RNa, which is included in the comb-shaped electrode composed of the first electrode layer 21 and the second electrode layer 22, may be referred to as the first extension direction. Similarly, the direction of extension of each line in the line-and-space pattern RNb, which is included in the third electrode layer 60, may be referred to as the second extension direction. In this embodiment, the first extension direction is the X direction, and the second extension direction is the Z direction. Therefore, these are not parallel to each other but different, and specifically, they are orthogonal to each other.

[0055] The pad electrodes 31 and 32 (Figure 4) are provided apart from each other on the other side (the bottom surface in Figure 4) of the insulating layer 10, opposite to the aforementioned side. The via electrode 41 penetrates the insulating layer 10 and has one end connected to the first electrode layer 21 and the other end connected to the pad electrode 31. The via electrode 42 penetrates the insulating layer 10 and has one end connected to the second electrode layer 22 and the other end connected to the pad electrode 32. Thus, each of the pad electrodes 31 and 32 functions as an external terminal for the first electrode layer 21 and the second electrode layer 22, respectively.

[0056] Pad electrodes 71 and 72 (Figure 4) are provided spaced apart from each other on the other surface (the bottom surface in Figure 4) of the insulating layer 10. Via electrode 81 penetrates the insulating layer 10 and has one end connected to the end 61 of the third electrode layer 60 and the other end connected to pad electrode 71. Via electrode 82 penetrates the insulating layer 10 and has one end connected to the end 62 of the third electrode layer 60 and the other end connected to pad electrode 72. Thus, pad electrodes 71 and 72 each function as external terminals for the ends 61 and 62 of the third electrode layer 60.

[0057] The impedance measuring device 301 is for measuring a first value based on the impedance between the first electrode layer 21 and the second electrode layer 22 of the sensor 101. This first value will also be referred to as the impedance-related value below. The impedance-related value may be a complex impedance value. Alternatively, the impedance-related value may be a component of the complex impedance value. In particular, when it is assumed that the substance being measured has sufficiently high insulating properties, the real component of the complex impedance value is considered to be sufficiently large, so there is often more interest in knowing the imaginary component than the real component. In that case, the imaginary component needs to be measured, but the real component does not necessarily need to be measured. For example, when measuring the electrical properties of an oil that typically has high insulating properties, there is often interest in the capacitance component of the complex impedance value, i.e., the capacitance value. In this case, the impedance-related value may be the capacitance value.

[0058] The electrical resistance measuring device 302 is for measuring a second value based on the electrical resistance between ends 61 and 62 of the third electrode layer 60 of the sensor 101. Here, as mentioned above, the third electrode layer 60 is made of a material having a temperature-dependent electrical resistivity, so this second value depends on the temperature of the third electrode layer 60. Therefore, this second value will also be referred to as the temperature-related value below. The temperature-related value may be the electrical resistance value between ends 61 and 62.

[0059] The electrical connections of the impedance measuring device 301 to the first electrode layer 21 and the second electrode layer 22 may be made via pad electrodes 31 and 32. Similarly, the electrical connections of the electrical resistance measuring device 302 to the ends 61 and 62 of the third electrode layer 60 may be made via pad electrodes 71 and 72.

[0060] The switching circuit 200 is configured to switch between circuit states depending on whether impedance-related values ​​or temperature-related values ​​are being measured. The specific states that can be switched between will be described later. The switching circuit 200 is connected to the end 61 of the third electrode layer 60 of the sensor 101. An example of the switching circuit 200 will be described in detail below.

[0061] The switching circuit 200 includes a switch section 221 (first switch section) and a switch section 222 (second switch section). The end 61 of the third electrode layer 60 of the sensor 101 is electrically connected to the power supply 210 via the switch section 221. In this embodiment, the end 61 of the third electrode layer 60 of the sensor 101 is electrically connected to the power supply 210 via the switch section 221 and resistor 220, which are connected in series with each other. The resistor 220, together with the third electrode layer 60, constitutes a voltage divider circuit of the power supply 210, and will be described in detail later with reference to Figure 14, but this makes it possible to detect a voltage value corresponding to the electrical resistance of the third electrode layer 60. In this embodiment, the electrical resistance measuring device 302 is configured to measure the potential of the end 61 of the third electrode layer 60, in other words, the voltage divide of the third electrode layer 60 in the voltage divider circuit, with ground 232 as the reference potential. Furthermore, the end 61 is electrically connected to ground 233 via the switch section 222. It is preferable that no elements such as resistors are provided between terminal 61 and ground 233. In other words, it is preferable that the switching circuit 200 is configured such that terminal 61 is short-circuited to ground 233 when the switch unit 222 is closed. Terminal 62 of the third electrode layer 60 may be connected to ground 231, thereby making the potential of terminal 62 the same as the reference potential of the electrical resistance measuring device 302. In Figure 14, terminal 61 is connected to ground 233 without any elements other than the switch unit 222, and terminal 62 is connected to ground 231 without any elements. In this case, the electrical state between terminals 61 and 62 of the third electrode layer 60 is short-circuited when the switch unit 222 is closed, and non-short-circuited when the switch unit 222 is open.

[0062] Figure 7 is a block diagram schematically showing the functional configuration of the control unit 300 (Figure 1). The control unit 300 has a switching control unit 320 that controls the switching circuit 200. When measuring impedance-related values, the switching control unit 320 opens switch unit 221 and closes switch unit 222. Therefore, when measuring impedance-related values, the switching control unit 320 electrically short-circuits the switching circuit 200 between ends 61 and 62 of the third electrode layer 60. On the other hand, when measuring temperature-related values, the switching control unit 320 closes switch unit 221 and opens switch unit 222. Therefore, when measuring temperature-related values, the switching control unit 320 does not electrically short-circuit the switching circuit 200 between ends 61 and 62 of the third electrode layer 60.

[0063] The control unit 300 may further include a measuring device control unit 330 and a measurement value storage unit 331. The measuring device control unit 330 controls the impedance measuring device 301 and the electrical resistance measuring device 302. The measuring device control unit 330 also receives impedance-related values ​​measured by the impedance measuring device 301 and temperature-related values ​​measured by the electrical resistance measuring device 302. The impedance-related values ​​and temperature-related values ​​are stored in the measurement value storage unit 331.

[0064] Furthermore, it is preferable that the measuring device control unit 330 of the control unit 300 is configured to be switchable between an input state in which it can receive signals from the electrical resistance measuring device 302 and a non-input state in which it cannot receive signals when the signals from the electrical resistance measuring device 302 are blocked. This non-input state may be an output state in which it can send signals to the electrical resistance measuring device 302. The measuring device control unit 330 is in a non-input state when both the switch unit 221 and the switch unit 222 are open. This prevents noise signals received by the third electrode layer 60 due to some factor from being transmitted into the control unit 300 via the electrical resistance measuring device 302. Therefore, it is prevented that such noise signals will adversely affect the operation of the control unit 300.

[0065] The control unit 300 may further include a measurement value evaluation unit 332. The measurement value evaluation unit 332 determines an evaluation result for the material based on both impedance-related values ​​and temperature-related values ​​stored in the measurement value storage unit 331. The measurement value evaluation unit 332 may correct the impedance-related values ​​with respect to the temperature-related values. For example, the capacitance value may be corrected with respect to the temperature-related values. This makes it possible to estimate the dielectric constant of the material being measured at a specific temperature with high accuracy.

[0066] Figure 8 is a block diagram schematically showing the hardware configuration of the control unit 300 (Figure 1). The hardware configuration of the control unit 300, in other words, the processing circuit, has a CPU (Central Processing Unit) 351, a storage unit 352, an input unit 353, and an output unit 354, which are connected to each other via a bus 350. The CPU 351 may be included in an MCU (Micro Controller Unit) or MPU. The storage unit 352 may have a non-temporary storage unit and a temporary storage unit. The temporary storage unit may be RAM (Random Access Memory). The non-temporary storage unit may be ROM (Read Only Memory) and / or a drive. The non-temporary storage unit may store a program that defines the processing to be executed by the control unit 300. By executing this program, the CPU 351 can execute the processing defined in the program. Some or all of the processing executed by the control unit 300 may be executed by dedicated logic circuits or other hardware. The temporary storage unit is used as a work area when the CPU 351 performs predetermined processing. The input unit 353 receives input signals to the control unit 300. The output unit 354 sends out output signals from the control unit 300.

[0067] <Measurement method> Next, the method for measuring the substance in this embodiment will be described. This measurement method may be performed using the measurement system 901 described above, and the following will describe that case.

[0068] Referring to FIGS. 10 and 11, in step ST10 (FIG. 9), the liquid LQ as the substance to be measured is brought into contact with the detection surface SF of the sensor 101. This state can be approximated electrically by the equivalent circuit shown in FIG. 12. Here, the impedance between the external terminals of the sensor 101, that is, between the pad electrode 31 and the pad electrode 32, is defined as Z, the impedance caused by the liquid LQ is defined as Z L and the impedance caused by the sensor 101 itself is defined as Z S If defined in this way, the impedance Z can be regarded as the combined impedance of the impedance Z L and the impedance Z S That is to say, Z = Z L + Z S can be regarded as such.

[0069] Regarding the above-mentioned impedance Z L and Z S Specifically, the following equations 1 / Z L = 1 / R L + j·ωC L and, Z S = -j·2 / ωC S can be regarded as being satisfied. Here, R L is the equivalent parallel resistance of Z L j is the imaginary unit, ω is the measurement angular frequency, C L is the equivalent parallel capacitance of Z L C S is the capacitance formed by the dielectric layer 50 between the first electrode layer 21 or the second electrode layer 22 and the detection surface SF.

[0070] C S is a fixed value independent of the liquid LQ, so Z S is also a fixed value. Therefore, by measuring Z between the external terminals of the sensor 101, Z L can be calculated. Z LTo know this with higher accuracy from the direct measurement Z, we need to know the Z to Z. S It is desirable for the influence to be small, therefore C S A larger size is preferable. S The value increases as the spacing H1 (Figure 4), which corresponds to the thickness d of the dielectric layer 50, decreases. Also, the relative permittivity ε of the dielectric layer 50 D The larger the value, the larger it becomes.

[0071] In particular, if the conductivity of the liquid LQ is sufficiently low, in other words, if the resistivity of the liquid LQ is sufficiently high, then the above 1 / Z L 1 / R in the formula L The components of this can be practically ignored. Therefore, 1 / Z L = j·ωC L It can be assumed that the following is satisfied. Here, C L The relative permittivity ε of liquid LQ is L It is thought to be proportional to ε. Therefore, the approximate relative permittivity ε of the liquid LQ can be obtained from the capacitance component of the impedance Z. L This allows us to know. Therefore, in this case, the impedance-related value measured by the impedance measuring device 301 may be capacitance. For example, oil usually has a sufficiently high resistivity, and therefore, when the liquid LQ is oil, the relative permittivity ε can be determined in this way. L In many cases, it is possible to learn about this.

[0072] Referring to Figure 13, in step ST20 (Figure 9), the control unit 300 opens switch unit 221 and closes switch unit 222. This electrically short-circuits ends 61 and 62 of the third electrode layer 60. While this state from step ST20 is maintained, in step ST30 (Figure 9), the impedance-related value based on the impedance between the first electrode layer 21 and the second electrode layer 22 of the sensor 101 is measured by the impedance measuring device 301.

[0073] Referring to Figure 14, in step ST40 (Figure 9), the control unit 300 closes switch unit 221 and opens switch unit 222. In this state, the ends 61 and 62 of the third electrode layer 60 are not electrically short-circuited. While this state from step ST40 is maintained, in step ST50 (Figure 9), the temperature-related value based on the electrical resistance between ends 61 and 62 of the third electrode layer 60 of the sensor 101 is measured by the electrical resistance measuring device 302. Specifically, the electrical resistance measuring device 302 measures the potential of end 61 of the third electrode layer 60 with ground 232 as the reference potential. This potential is the voltage division of the electrical resistance of the third electrode layer 60 in a voltage divider circuit composed of the resistor 220 and the electrical resistance of the third electrode layer 60. This voltage division depends on the electrical resistance of the third electrode layer 60, and this electrical resistance depends on temperature. Therefore, the measurement of this voltage division corresponds to the measurement of the temperature-related value described above. From these temperature-related values, we can determine the temperature of the liquid LQ.

[0074] As can be seen from the above explanation, step ST50 is not performed simultaneously with step ST30. On the other hand, if step ST50 is performed within a sufficiently short time after step ST30, the temperature of the liquid LQ when the impedance-related value is measured by step ST30 can be considered to be substantially the same as the temperature measured by step ST50. Therefore, not only the impedance-related value but also the temperature of the liquid LQ when it is measured can be substantially known. Furthermore, if the control unit 300 has a measurement value evaluation unit 332, in step ST60 (Figure 9), the measurement value evaluation unit 332 of the control unit 300 may determine the evaluation result for the liquid LQ based on both the impedance-related value and the temperature-related value.

[0075] In the flow chart shown in Figure 9, a first measurement is performed by combining steps ST20 and ST30 to measure a first value, and a second measurement is performed by combining steps ST40 and ST50 to measure a second value. The order of the first measurement (steps ST20 and ST30) and the second measurement (steps ST40 and ST50) may be reversed. That is, the temperature-related value based on electrical resistance may be measured first, followed by the impedance-related value based on impedance.

[0076] <Effects> The measurement system 901 of this embodiment has the function of measuring the electrical characteristics of liquid LQ by measuring impedance-related values ​​based on the impedance between the first electrode layer 21 and the second electrode layer 22 of the sensor 101, and the function of measuring the temperature of liquid LQ by measuring temperature-related values ​​based on the electrical resistance between the ends 61 and 62 of the third electrode layer 60 of the sensor 101. The third electrode layer 60 has a portion that overlaps with at least a portion of the first electrode layer 21 and the second electrode layer 22 in the Y-axis direction in a plan view. As a result, firstly, the size of the sensor 101 in a plan view parallel to the Z-axis and X-axis can be reduced compared to the case where the third electrode layer 60 does not have such a portion. Secondly, when measuring the electrical characteristics of liquid LQ, the third electrode layer 60 can shield at least a portion of the first electrode layer 21 and the second electrode layer 22 for the measurement from noise. Therefore, the configuration of the sensor 101 can be simplified compared to the case where a separate electrode layer for shielding is provided. From the above, it is possible to make the sensor 101 for measuring the electrical properties and temperature of the liquid LQ simple in configuration and small in size, while reducing the adverse effects of noise on the measurement of the electrical properties of the liquid LQ.

[0077] Furthermore, as described above, the absence of a separate electrode layer for shielding makes the manufacturing of the sensor 101 simpler. Specifically, if a separate electrode layer for shielding were required, the pattern design of the sensor would become complex. In contrast, according to this embodiment, the pattern design can be simplified.

[0078] Furthermore, in this embodiment, the third electrode layer 60 constituting the temperature detection unit DT is provided directly beneath the first electrode layer 21 and the second electrode layer constituting the impedance detection unit DI, with approximately the same size. This allows for accurate measurement of the temperature near the first electrode layer 21 and the second electrode layer.

[0079] The first extending direction along which each line of the line-and-space pattern RNa (Figure 5) included in the comb-tooth electrode extends, and the second extending direction along which each line of the line-and-space pattern RNb (Figure 6) included in the third electrode layer 60 extends, are different from each other and preferably orthogonal. This makes it possible to suppress crosstalk between the lines of the line-and-space pattern RNa (Figure 5) in the capacitance sensing unit DI and the lines of the line-and-space pattern RNb (Figure 6) in the temperature sensing unit DT. This makes it possible to improve the accuracy of impedance measurement and temperature measurement, respectively.

[0080] In the measurement system 901, when measuring impedance-related values, i.e., measuring the electrical characteristics of liquid LQ, the switch unit 221 may be in the open state and the switch unit 222 may be in the closed state, as shown in Figure 13. This causes the potential of the end 61 of the third electrode layer 60 to be at ground potential. Therefore, the effect of the third electrode layer 60 shielding at least a portion of the first electrode layer 21 and the second electrode layer 22 from noise for the measurement is further enhanced.

[0081] In the measurement system 901, when measuring temperature-related values, i.e., measuring the temperature of liquid LQ, the switch unit 221 may be in a closed state and the switch unit 222 may be in an open state, as shown in Figure 14. This applies a potential from the power supply 210 to the end 61 of the third electrode layer 60. Therefore, by using this potential application to measure the electrical resistance between the end 61 and the end 62 of the third electrode layer 60, the temperature of liquid LQ can be measured.

[0082] In the measurement system 901, when measuring impedance-related values, i.e., measuring the electrical characteristics of the liquid LQ, the ends 61 and 62 of the third electrode layer 60, which functions as a shield electrode, may be electrically short-circuited, as shown in Figure 13. This prevents noise from inducing a voltage between the ends 61 and 62 of the third electrode layer 60. Therefore, the shielding effect of the third electrode layer 60 during electrical characteristic measurement can be further enhanced. On the other hand, when measuring temperature-related values, i.e., measuring the temperature of the liquid LQ, it is necessary to measure the electrical resistance between the ends 61 and 62 of the third electrode layer 60. In this case, the ends 61 and 62 of the third electrode layer 60 are not electrically short-circuited, as shown in Figure 14. This avoids the short circuit making it impossible to measure the electrical resistance between the ends 61 and 62 of the third electrode layer 60. From the above, it is possible to measure the temperature of the liquid LQ based on the electrical resistance between ends 61 and 62 of the third electrode layer 60, while when measuring the electrical characteristics of the liquid LQ instead of the temperature, the shielding effect of the third electrode layer 60 can be further enhanced by short-circuiting the area between ends 61 and 62.

[0083] In the measurement system 901, the measurement value evaluation unit 332 (Figure 7) may determine an evaluation result for the liquid LQ based on both an impedance-related value corresponding to the electrical characteristics of the liquid LQ and a corresponding temperature-related value for the temperature of the liquid LQ. This allows the temperature of the liquid LQ to be taken into consideration when determining any evaluation result related to the electrical characteristics of the liquid LQ. For example, if the electrical characteristics of the liquid LQ substantially depend on the composition or degradation of the liquid LQ and the temperature, the composition or degradation of the liquid LQ can be evaluated more accurately by eliminating the influence of temperature dependence.

[0084] In the measurement system 901, the insulating layer 10 covers the other side of the third electrode layer 60 (the side in the positive Y direction from the third electrode layer 60 in Figure 4). This reduces the temperature difference between the insulating layer 10 and the third electrode layer 60. Therefore, the measurement accuracy of the liquid LQ can be improved.

[0085] The liquid LQ measurement method of this embodiment measures the electrical characteristics of the liquid LQ by measuring an impedance-related value based on the impedance between the first electrode layer 21 and the second electrode layer 22 of the sensor 101, and measures the temperature of the liquid LQ by measuring a temperature-related value based on the electrical resistance between the ends 61 and 62 of the third electrode layer 60 of the sensor 101. The third electrode layer 60 has a portion that overlaps with at least a part of the first electrode layer 21 and the second electrode layer 22 in the Y-axis direction in a plan view. As a result, firstly, the size of the sensor 101 in a plan view parallel to the Z-axis and X-axis can be reduced compared to the case where the third electrode layer 60 does not have such a portion. Secondly, when measuring the electrical characteristics of the liquid LQ, the third electrode layer 60 can shield at least a part of the first electrode layer 21 and the second electrode layer 22 used for the measurement from noise. Therefore, the configuration of the sensor 101 can be simplified compared to the case where a separate electrode layer for shielding is provided. Based on the above, the sensor 101 for measuring the electrical properties and temperature of the liquid LQ can have a simple configuration and a small size, while reducing the adverse effects of noise on the measurement of the electrical properties of the liquid LQ.

[0086] In this measurement method, when measuring impedance-related values, i.e., measuring the electrical characteristics of liquid LQ, the switch unit 221 may be in the open state and the switch unit 222 may be in the closed state, as shown in Figure 13. This causes the potential at the end 61 of the third electrode layer 60 to be at ground potential. Therefore, the effect of the third electrode layer 60 shielding at least a portion of the first electrode layer 21 and the second electrode layer 22 from noise for the measurement is further enhanced.

[0087] In this measurement method, when measuring temperature-related values, i.e., measuring the temperature of liquid LQ, switch unit 221 may be in a closed state and switch unit 222 may be in an open state. As a result, a potential is applied from the power supply 210 to the end 61 of the third electrode layer 60. By using this potential application to measure the electrical resistance between the end 61 and the end 62 of the third electrode layer 60, the temperature of liquid LQ can be measured.

[0088] In this measurement method, when measuring impedance-related values, i.e., measuring the electrical characteristics of the liquid LQ, the ends 61 and 62 of the third electrode layer 60, which functions as a shield electrode, may be electrically short-circuited, as shown in Figure 13. This prevents noise from inducing a voltage between the ends 61 and 62 of the third electrode layer 60. Therefore, the shielding effect of the third electrode layer 60 during the measurement of electrical characteristics can be further enhanced. On the other hand, when measuring temperature-related values, i.e., measuring the temperature of the liquid LQ, it is necessary to measure the electrical resistance between the ends 61 and 62 of the third electrode layer 60, as shown in Figure 14. In this case, the ends 61 and 62 of the third electrode layer 60 are not electrically short-circuited. This avoids the short circuit making it impossible to measure the electrical resistance between the ends 61 and 62 of the third electrode layer 60. From the above, it is possible to measure the temperature of the liquid LQ based on the electrical resistance between ends 61 and 62 of the third electrode layer 60, while when measuring the electrical characteristics of the liquid LQ instead of the temperature, the shielding effect of the third electrode layer 60 can be further enhanced by short-circuiting the area between ends 61 and 62.

[0089] In this measurement method, the evaluation result for liquid LQ may be determined based on both an impedance-related value corresponding to the electrical properties of the liquid LQ and a corresponding temperature-related value for the temperature of the liquid LQ. This allows the temperature of the liquid LQ to be taken into consideration when determining any evaluation result related to the electrical properties of the liquid LQ. For example, if the electrical properties of the liquid LQ substantially depend on the composition or degradation of the liquid LQ and the temperature, the composition or degradation of the liquid LQ can be evaluated more accurately by applying a temperature correction.

[0090] In this measurement method, the object brought into contact with the detection surface SF of the sensor 101 may be a liquid LQ. Since liquids are fluid, it is difficult for a gap to form between the liquid LQ to be measured and the detection surface SF. Therefore, measurement errors caused by this gap can be reduced.

[0091] In this measurement method, the liquid LQ brought into contact with the detection surface SF of the sensor 101 may be oil. Since oil generally has high electrical resistance, evaluating the properties of oil solely based on differences in electrical resistance may result in insufficient accuracy. In contrast, in this embodiment, the dielectric constant of the oil can be considered, thereby enabling a more accurate evaluation of the oil's properties.

[0092] According to the sensor 101 of this embodiment, the electrical characteristics of liquid LQ can be measured by measuring a value corresponding to the impedance between the first electrode layer 21 and the second electrode layer 22, and the temperature of liquid LQ can be measured by measuring a value corresponding to the electrical resistance between the ends 61 and 62 of the third electrode layer 60. The third electrode layer 60 has a portion that overlaps with at least a part of the first electrode layer 21 and the second electrode layer 22 in the Y-axis direction in a plan view. As a result, firstly, the size of the sensor 101 in a plan view parallel to the Z-axis and X-axis can be reduced compared to the case where the third electrode layer 60 does not have such a portion. Secondly, when measuring the electrical characteristics of liquid LQ, the third electrode layer 60 can shield at least a part of the first electrode layer 21 and the second electrode layer 22 used for the measurement from noise. Therefore, the configuration of the sensor 101 can be simplified compared to the case where a separate electrode layer for shielding is provided. Based on the above, the sensor 101 for measuring the electrical properties and temperature of the liquid LQ can have a simple configuration and a small size, while reducing the adverse effects of noise on the measurement of the electrical properties of the liquid LQ.

[0093] In the sensor 101, firstly, the first electrode layer 21 and the second electrode layer 22 constituting the impedance detection unit DI may constitute a pair of comb-tooth electrodes, thereby reducing the size of the sensor 101 in plan view while ensuring the accuracy of measuring the electrical characteristics of the liquid LQ by the impedance detection unit DI. Secondly, the third electrode layer 60 constituting the temperature detection unit DT may include a second line-and-space pattern RNb, thereby making it easy to increase the total length of the third electrode layer 60. This allows for reducing the size of the sensor 101 in plan view while ensuring the accuracy of measuring the temperature of the liquid LQ by the temperature detection unit DT. Thirdly, the region where the second line-and-space pattern RNb is located may encompass the region where the first line-and-space pattern RNa is located. This enhances the shielding effect of the third electrode layer 60 including the second line-and-space pattern RNb on the first electrode layer 21 and the second electrode layer 22 including the first line-and-space pattern RNa. Based on the above, the size of the sensor 101 can be reduced, and the adverse effects of noise on the measurement of the electrical properties of liquid LQ can be further reduced.

[0094] In the sensor 101, firstly, the distance H1 (Figure 4) between the detection surface SF and the first electrode layer 21 and the second electrode layer 22 can be relatively small. Correspondingly, the thickness of the dielectric layer 50 located in this distance is also small. The measurement value by the impedance detection unit DI is determined by the dielectric layer 50 having a surface as the detection surface SF and the liquid LQ in contact with the detection surface SF. As described above, the small thickness of the dielectric layer 50 reduces the influence of the dielectric on the measurement value. This makes it possible to improve the measurement accuracy of the electrical properties of the liquid LQ. Secondly, the distance H1 between the third electrode layer 60 and the first electrode layer 21 and the second electrode layer 22 is relatively large. This makes it easy to sufficiently separate the third electrode layer 60 from the first electrode layer 21 and the second electrode layer 22 that constitute the impedance detection unit DI. Therefore, when measurements are being taken by the impedance detection unit DI, it is suppressed that electric field lines extend to the third electrode layer 60 instead of the first electrode layer 21 and the second electrode layer 22 that constitute the impedance detection unit DI. Thus, the measurement accuracy of the electrical properties of the liquid LQ can be improved.

[0095] The dielectric layer 50 (Figure 4) of the sensor 101 may be made of a sintered body. Compared to the case where the dielectric layer 50 is made of an unsintered body, it is easier to increase the manufacturing efficiency of the sensor 101. In particular, if the insulating layer 10 is also a sintered body, forming the dielectric layer 50 and the insulating layer 10 as a single sintered body makes it less likely for defects to occur starting at the interface between them. As a result, properties such as chemical resistance and thermal shock resistance are improved.

[0096] In the above, we have described in detail the case where the substance being measured is a liquid LQ (Figures 10 and 11), but the substance may be a semi-solid instead of a liquid. Semi-solids, though not as easily as liquids, are still easy to bring into close contact with the detection surface SF of the sensor 101 (see Figure 11). Therefore, although not as easy as liquids, they are still suitable as the substance to be measured by the sensor 101.

[0097] The insulating layer 10 may cover the other side of the third electrode layer 60 (the positive Y direction side in Figure 4), as shown in Figure 4. In other words, the insulating layer 10 may cover the bottom surface of the third electrode layer 60 in Figure 4. On the other hand, a modified example in which the insulating layer 10 does not cover the other side of the third electrode layer 60 (the positive Y direction side in Figure 4) may be applied. In other words, a modified example in which the insulating layer 10 does not cover the bottom surface of the third electrode layer 60 in Figure 4 may be applied. In this modified example, via electrodes 81 and 82 are omitted.

[0098] The impedance measuring device 301 and the electrical resistance measuring device 302 may be separate devices, as shown in Figure 1, etc. As a variation, a single device configured to have both the functions of the impedance measuring device 301 (first measuring device) and the electrical resistance measuring device 302 (second measuring device) may be used. In that case, the single device is considered to be the impedance measuring device (first measuring device) and the electrical resistance measuring device (second measuring device). [Explanation of Symbols]

[0099] 10: Insulating layer 21: First electrode layer 22: Second electrode layer 50: Dielectric layer 60: Third electrode layer 61: The first edge 62: The second end 90: Control Unit 101: Sensor 200: Switching Circuit 210: Power supply 221: First switch section 222: Second switch section 300: Control Unit 301: Impedance measuring device (first measuring device) 302: Electrical resistance measuring device (second measuring device) 320: Switching Control Unit 330: Measuring device control unit 331: Measurement value storage unit 332: Measurement value evaluation unit 901: Measurement System DI: Impedance detection unit DT: Temperature detection unit LQ: Liquid RNa: First line and space pattern RNb: Second line and space pattern SF: Detection surface

Claims

1. A measuring system for measuring the electrical properties and temperature of a substance in contact with a detection surface, It is equipped with a sensor, and the sensor is Insulating layer and, A first electrode layer and a second electrode layer are arranged on the insulating layer and are spaced apart from each other in a plan view perpendicular to the thickness direction, A dielectric layer having a surface as a detection surface, disposed on one side of the first electrode layer and the second electrode layer, and covering the first electrode layer and the second electrode layer, A third electrode layer is disposed on the other side of the first electrode layer and the second electrode layer, separated from the first electrode layer and the second electrode layer by the insulating layer, having a first end and a second end, made of a material having a temperature-dependent electrical resistivity, and having a portion that overlaps with at least a part of the first electrode layer and the second electrode layer in a plan view, The measurement system further includes, A first measuring device for measuring a first value based on the impedance between the first electrode layer and the second electrode layer of the sensor, A second measuring device for measuring a second value based on the electrical resistance between the first and second ends of the third electrode layer of the sensor, A measurement system comprising: a switching circuit connected to the first end of the third electrode layer of the sensor, which can switch the circuit state depending on whether a first value measurement or a second value measurement is performed.

2. A measurement system according to claim 1, The switching circuit includes a first switch section and a second switch section. The first end of the third electrode layer of the sensor is connected to the power supply via the first switch portion and to ground via the second switch portion. The measurement system further includes a control unit, The control unit is a measurement system that, when measuring the first value, opens the first switch and closes the second switch.

3. A measurement system according to claim 1, The switching circuit includes a first switching section and a second switching section. The first end of the third electrode layer of the sensor is connected to the power supply via the first switch portion and to ground via the second switch portion. The measurement system further includes a control unit, The control unit is a measuring system that, when measuring the second value, closes the first switch and opens the second switch.

4. A measurement system according to claim 1, The measurement system further comprises a control unit, and the control unit is When measuring the first value, the switching circuit is set to electrically short-circuit the first end and the second end of the third electrode layer. A measurement system in which, when measuring the second value, the switching circuit is not in a state that electrically short-circuits the first end and the second end of the third electrode layer.

5. A measurement system according to any one of claims 2 to 4, The control unit has a measurement value evaluation unit that determines an evaluation result for the substance based on both the first value and the second value, in a measurement system.

6. A measurement system according to any one of claims 1 to 4, The insulating layer covers the other side of the third electrode layer in the measurement system.

7. a) The process includes bringing a liquid or semi-solid substance into contact with the sensing surface of the sensor, and the sensor is Insulating layer and, A first electrode layer and a second electrode layer are arranged on the insulating layer and are spaced apart from each other in a plan view perpendicular to the thickness direction, A dielectric layer having a surface as a detection surface, disposed on one side of the first electrode layer and the second electrode layer, and covering the first electrode layer and the second electrode layer, The third electrode layer is disposed on the other side of the first electrode layer and the second electrode layer so as to be separated from the first electrode layer and the second electrode layer by the insulating layer, and has first and second ends, is made of a material having a temperature-dependent electrical resistivity, and has a portion that overlaps with at least a portion of the first electrode layer and the second electrode layer in a plan view, b) A step of measuring a first value based on the impedance between the first electrode layer and the second electrode layer of the sensor, c) A step of measuring a second value based on the electrical resistance between the first and second ends of the third electrode layer of the sensor, A method for measuring substances, comprising the following features.

8. A method for measuring a substance according to claim 7, A switching circuit is connected to the first end of the third electrode layer of the sensor, the switching circuit includes a first switch section and a second switch section, and the first end of the third electrode layer of the sensor is connected to a power supply via the first switch section and to ground via the second switch section. A method for measuring a substance, wherein, in (b) above, the first switch unit is in an open state and the second switch unit is in a closed state.

9. A method for measuring a substance according to claim 7, A switching circuit is connected to the first end of the third electrode layer of the sensor, the switching circuit includes a first switch section and a second switch section, and the first end of the third electrode layer of the sensor is connected to a power supply via the first switch section and to ground via the second switch section. A method for measuring a substance, wherein, in c) above, the first switch unit is in a closed state and the second switch unit is in an open state.

10. A method for measuring a substance according to claim 7, The above b) is performed while electrically short-circuiting the first end and the second end of the third electrode layer. The above-mentioned c) is a method for measuring a substance without electrically short-circuiting the first end and the second end of the third electrode layer.

11. A method for measuring a substance according to any one of claims 7 to 10, d) A step of determining an evaluation result for the substance based on both the first value and the second value, A method for measuring substances that further incorporates these features.

12. A method for measuring a substance according to any one of claims 7 to 10, A method for measuring a substance, wherein the substance is a liquid.

13. A method for measuring a substance according to any one of claims 7 to 10, A method for measuring a substance, wherein the substance is oil and the first value is capacitance.

14. A sensor for measuring the electrical properties and temperature of a substance in contact with a detection surface, Insulating layer and, An impedance detection unit comprising a first electrode layer and a second electrode layer arranged on the insulating layer and spaced apart from each other in a plan view perpendicular to the thickness direction, A dielectric layer having a surface as a detection surface, disposed on one side of the first electrode layer and the second electrode layer, and covering the first electrode layer and the second electrode layer, A temperature sensing unit comprising a third electrode layer, which is positioned on the other side of the first and second electrode layers so as to be separated from the first and second electrode layers by the insulating layer, is made of a material having a temperature-dependent electrical resistivity, and has a portion that overlaps with at least a part of the first and second electrode layers in a plan view, A sensor equipped with the following features.

15. The sensor according to claim 14, The first electrode layer and the second electrode layer constitute a pair of comb-tooth electrodes that interlock with each other. In the plan view, the pair of comb-tooth electrodes include a first line-and-space pattern, the third electrode layer includes a second line-and-space pattern, and the region where the second line-and-space pattern is arranged encompasses the region where the first line-and-space pattern is arranged.

16. A sensor according to any one of claims 14 or 15, A sensor in which, in a cross-sectional view, the distance between the detection surface and the first electrode layer and the second electrode layer is smaller than the distance between the third electrode layer and the first electrode layer and the second electrode layer.

17. A sensor for measuring electrical characteristics or temperature according to claim 14 or 15, The aforementioned dielectric layer is made of a sintered body, and the sensor is provided.

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