Impedance Sensor

Abstract

To evaluate the impedance in a wide range of an arbitrary material in a fluid (the impedance of a fluid in which an arbitrary material is dissolved).SOLUTION: An excitation electrode 11 and a measurement electrode 12 are formed of center conductor lines 11a and 12a, insulating layers 11b and 12b, and external layer conductor lines 11c and 12c. The external conductor lines 11c and 12c are maintained at a natural immersion potential of pure water 2 so that the expansion of the natural immersion potential is limited and the natural immersion potential is used as a reference potential. The potential of a solute 3 in the pure water 2 is surely measured for a wide range, the impedance is measured, and the concentration of the solute 3 is determined accurately, instantly and locally.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an impedance sensor that measures the impedance of a substance in a fluid (the impedance of a fluid in which a substance is dissolved). [Background technology]

[0002] For example, a wire mesh sensor is known as an impedance sensor for obtaining information on the presence of gas in a liquid or the concentration of solutes in the liquid (see, for example, Patent Document 1). A wire mesh sensor has a structure in which a first wire electrode (excitation electrode) and a second wire electrode (measurement electrode) are crossed at a predetermined distance, and the excitation electrode and the measurement electrode are arranged in a square lattice pattern. By transmitting and receiving signals between the excitation electrode and the measurement electrode, the signal strength is measured (potential is measured) to measure impedance, and the state of the gas in the fluid or the state of the solute concentration in the fluid can be evaluated.

[0003] In recent years, there has been an increasing demand for the ability to measure a wide range of impedance and determine the concentration of substances in a fluid. In the field of impedance sensors that have excitation and measurement electrodes, there is a need for a technology that can measure a wide range of impedance. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-127874 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made in consideration of the above situation, and aims to provide an impedance sensor that can reliably measure the impedance of any substance (e.g., a solute) in a fluid (the impedance of a fluid in which the any substance is dissolved) over a wide range, and determine the status of the any substance (e.g., the concentration of the solute). [Means for solving the problem]

[0006] In order to achieve the above object, the impedance sensor of the present invention according to claim 1 comprises: an excitation electrode that applies a predetermined potential; a measurement electrode provided adjacent to the excitation electrode, immersed in the fluid, and configured to measure a potential by transmitting and receiving a signal between the measurement electrode and the excitation electrode; At least one of the excitation electrode and the measurement electrode is The insulating member includes a conductor member, an insulating member, and an outer layer conductor member. The aforementioned Outer layer conductor material teeth, The excitation electrode and the measurement electrode are immersed in a fluid, and a natural immersion potential of the fluid is applied to the fluid.

[0007] In the present invention according to claim 1, at least one of the excitation electrode and the measurement electrode (either either or both Outer layer conductor material Apply natural immersion potential to (natural immersion potential is given) Therefore, it is possible to limit the spread of the electric field lines and measure the impedance of the medium (for example, a fluid in which any substance is dissolved) between the excitation electrode and the measurement electrode, with the natural immersion potential as the reference potential. Outer layer conductor material The shape and arrangement of the electrodes can be set arbitrarily. It is also possible to directly measure the potential difference.

[0008] This makes it possible to reliably measure the impedance of any substance (e.g., a solute) in a fluid (the impedance of a fluid in which the substance is dissolved) over a wide range, and to determine the status of the substance (e.g., the concentration of the solute).

[0009] An impedance sensor according to a second aspect of the present invention is the impedance sensor according to the first aspect, further comprising: the conductor member, the insulating member, and the outer layer conductor member are characterized in that they are arranged one on top of the other.

[0010] In the present invention according to claim 2, a conductive member, an insulating member, Outer layer conductor material The impedance sensor may have a structure in which the electrodes are stacked (a concentric stacked structure, a structure in which plate-like members are stacked, etc.).

[0011] Furthermore, the impedance sensor of the present invention according to claim 3 is characterized in that in the impedance sensor according to claim 2, the excitation electrode and the measurement electrode are adjacent to each other (arranged at a distance from each other) with the conductor members being spaced apart.

[0012] In the present invention according to claim 3, the impedance sensor can be configured such that the conductor members are arranged close to each other (arranged at intervals).

[0013] Furthermore, the impedance sensor of the present invention according to claim 4 is the impedance sensor according to claim 3, wherein the excitation electrode and the measurement electrode are elongated, the excitation electrode and the measurement electrode are disposed in close proximity to each other by being disposed so as to intersect, the conductor member is a central conductor wire, an insulating layer is disposed on the central conductor wire as the insulating member, and the insulating layer the outer layer conductor member an outer layer conductor wire is arranged as a central conductor wire, and at least one of the excitation electrode and the measurement electrode is a member having a triple structure of the central conductor wire, the insulating layer, and the outer layer conductor wire, and the central conductor wire is exposed at the intersection, and impedance is measured by measuring the potential with the measurement electrode.

[0014] In the present invention according to claim 4, at least one of the excitation electrode and the measurement electrode (either one or both) has a triple structure, and a natural immersion potential is applied to the outer layer conductor wire, thereby limiting the spread of the electric field lines and making it possible to measure the impedance of the medium between the excitation electrode and the measurement electrode with the natural immersion potential as the reference potential.

[0015] Since the impedance is measured within the range of the size of the exposed central conductor wire, by arbitrarily setting the size of the exposure and the distance between the excitation electrode and the measurement electrode, it is possible to limit the range of the electric field lines in a plane perpendicular to the equipotential lines within an arbitrary dynamic range, and it is possible to reliably measure the impedance of any substance (e.g., a solute) in a fluid (the impedance of a fluid in which any substance is dissolved) over a wide range.

[0016] Furthermore, the impedance sensor of the present invention according to claim 5 is the impedance sensor according to claim 4, One of the excitation electrode and the measurement electrode is a member having a triple structure of the central conductor wire, the insulating layer, and the outer layer conductor wire. It is characterized by:

[0017] In the present invention according to claim 5, either the excitation electrode or the measurement electrode can have a triple structure.

[0018] Furthermore, the impedance sensor of the present invention according to claim 6 is characterized in that in the impedance sensor according to claim 5, the other of the excitation electrode or the measurement electrode is a double-structure member of the central conductor wire and the insulating layer, and the central conductor wire at the intersection is exposed.

[0019] In the present invention according to claim 6, the other of the excitation electrode and the measurement electrode can have a double structure of a central conductor wire and an insulating layer. That is, the other of the excitation electrode and the measurement electrode can have a double structure, and one of the excitation electrode and the measurement electrode can have a triple structure.

[0020] Furthermore, an impedance sensor according to a seventh aspect of the present invention is the impedance sensor according to the fifth aspect, wherein the central conductor wire of the other of the excitation electrode and the measurement electrode is a single member.

[0021] In the present invention according to claim 7, the other of the excitation electrode and the measurement electrode can have a structure in which the center conductor wire is a single member. That is, the other of the excitation electrode and the measurement electrode can have a structure in which the center conductor wire is a single member, and one of the excitation electrode and the measurement electrode can have a triple structure.

[0022] Furthermore, an impedance sensor according to an eighth aspect of the present invention is the impedance sensor according to the fourth aspect, Both the excitation electrode and the measurement electrode are members having a triple structure of the central conductor wire, the insulating layer, and the outer layer conductor wire. It is characterized by:

[0023] In the present invention according to claim 8, both the excitation electrode and the measurement electrode can have a triple structure.

[0024] Furthermore, the impedance sensor of the present invention according to claim 9 is characterized in that, in the impedance sensor according to any one of claims 4 to 8, the area where the central conductor wire is exposed at the intersection in the triple-structure member is set in a state to obtain a desired dynamic range.

[0025] In the present invention according to claim 9, the desired dynamic range can be obtained by changing the area of ​​the exposed central conductor wire. That is, by narrowing the area of ​​the exposed central conductor wire, it becomes possible to measure impedance values ​​over a wider range, thereby widening the dynamic range.

[0026] Furthermore, the impedance sensor of the present invention according to claim 10 is characterized in that, in the impedance sensor according to any one of claims 4 to 9, the distance between the axes of the excitation electrode and the measurement electrode is set to a state in which a desired dynamic range is obtained.

[0027] In the present invention according to claim 10, a desired dynamic range can be obtained by changing the distance between the axes of the excitation electrode and the measurement electrode. That is, by increasing the distance between the axes of the excitation electrode and the measurement electrode, it becomes possible to measure impedance values ​​over a wider range, thereby widening the dynamic range.

[0028] Furthermore, the impedance sensor of the present invention according to claim 11 is characterized in that, in the impedance sensor according to any one of claims 4 to 10, a plurality of excitation electrodes and a plurality of measurement electrodes are provided, and the excitation electrodes and the measurement electrodes are arranged in a grid pattern by being spaced apart from each other.

[0029] In the present invention according to claim 11, the impedance sensor can be a lattice-shaped structure.

[0030] Furthermore, the impedance sensor of the present invention according to claim 12 is characterized in that in the impedance sensor according to claim 11, the excitation electrodes and measurement electrodes arranged in a grid pattern are arranged across multiple layers.

[0031] In the present invention according to claim 12, the impedance sensor can be one in which lattice-like structures are arranged in multiple layers.

[0032] Furthermore, the impedance sensor of the present invention according to claim 13 is characterized in that, in the impedance sensor according to any one of claims 4 to 12, the measurement electrodes are arranged in two layers, and the excitation electrode is arranged between the layers of the measurement electrodes.

[0033] In the present invention according to claim 13, measurement electrodes are arranged in two layers on either side of the excitation electrode, so that the two measurement electrodes can simultaneously measure electrical signals (potentials) with different dynamic ranges, and can measure low impedance values ​​while also measuring high impedance values ​​in detail. [Effects of the Invention]

[0034] The impedance sensor of the present invention can reliably measure the impedance of any substance (e.g., a solute) in a fluid (the impedance of a fluid in which the substance is dissolved) over a wide range, making it possible to determine the status of the substance (e.g., the concentration of the solute). [Brief explanation of the drawings]

[0035] [Figure 1] 1 is an external view illustrating an example of the arrangement of an impedance sensor (grid-like structure) according to an embodiment of the present invention. FIG. [Figure 2] FIG. 1 is a conceptual diagram illustrating a measurement situation of an impedance sensor (grid-like structure) according to an embodiment of the present invention. [Figure 3] FIG. 2 is a diagram showing the configuration of a main part of an impedance sensor (electrode member). [Figure 4] FIG. 1 is a conceptual diagram of equipotential lines (equipotential surfaces) of an impedance sensor (electrode member). [Figure 5] 1 is a graph showing the relationship between signal strength and opening area (width). [Figure 6] 10 is a graph of signal strength versus distance between electrode members. [Figure 7] FIG. 10 is a diagram showing the configuration of a main part of an impedance sensor (electrode member) according to another embodiment. [Figure 8] FIG. 10 is a diagram showing the configuration of a main part of an impedance sensor (electrode member) according to another embodiment. [Figure 9] FIG. 10 is a diagram showing the configuration of a main part of an impedance sensor (electrode member) according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0036] Figure 1 shows a conceptual situation in which an impedance sensor (lattice-like structure) according to one embodiment of the present invention is placed in a fluid in which a high-conductivity solute is dissolved in low-conductivity pure water; Figure 2 shows a conceptual situation explaining the measurement situation of the impedance sensor (lattice-like structure); Figure 3 shows a schematic configuration of the main parts of the impedance sensor (electrode member); Figure 4 shows a conceptual situation of the equipotential lines (equipotential surfaces) of the impedance sensor (electrode member); Figure 5 is a graph for explaining the dynamic range, showing the relationship between the signal strength of the measurement signal and the opening area (width); and Figure 6 is a graph for explaining the dynamic range, showing the relationship between the signal strength of the measurement signal and the distance between the electrode members.

[0037] As shown in Figure 1, a container 1 is filled with a fluid 4, which is made by dissolving a high-conductivity solute 3 in low-conductivity pure water 2. An impedance sensor 6 is immersed in the fluid 4 inside the container 1, and an electrical signal is exchanged between the electrodes of the impedance sensor 6 to measure the potential difference (impedance), which leads to the conductivity, and the distribution of the solute 3 in the fluid 4 is measured.

[0038] The impedance sensor 6 is composed of a long excitation electrode 11 (excitation electrode 11 that applies a predetermined potential) and a long measurement electrode 12 (measurement electrode 12 that measures the potential) that is provided so as to intersect with the excitation electrode 11. A plurality of excitation electrodes 11 and measurement electrodes 12 (six in the figure) are provided, and are arranged in a grid pattern with spaces between them.

[0039] As shown in Figure 2, the excitation electrodes 11 are connected to a power supply 15 via switches 14a, 14b, 14c, 14d, etc. An electrical signal is output from the power supply 15 via the desired switch 14 (a predetermined potential is applied). The electrical signal sent to the excitation electrode 11 is received by the measurement electrode 12 at the intersection (the potential is measured). The impedance of the received electrical signal (measured potential) is measured based on the strength of the excitation signal, and the degree of electrical conductivity of the solute 3 at the intersection is determined.

[0040] For example, by turning on switch 14a, the exchange of electrical signals between excitation electrode 11 on the left side of the figure and all measurement electrodes 12 is measured. The measurement signal is strong at the portion of the plane where solute 3 with high conductivity is present, and the measurement signal is weak at the portion of the plane where water with low conductivity is present. Therefore, the impedance of solute 3 can be directly measured, and the concentration state of solute 3 within the plane of the lattice structure can be grasped.

[0041] The shapes of the excitation electrode 11 and the measurement electrode 12 in the longitudinal direction and the shape of their intersections (arrangement) can be arbitrarily configured. The cross-sectional shapes of the excitation electrode 11 and the measurement electrode 12 can be any shape, such as a circle, an ellipse, or a polygon.

[0042] The configurations of the excitation electrode 11 and the measurement electrode 12 will be specifically described with reference to Figures 3 and 4. Figure 3 shows the configuration of the main parts of the excitation electrode 11 and the measurement electrode 12, and Figure 4 shows the state of the equipotential lines (equipotential surfaces).

[0043] 3, the excitation electrode 11 (at least one of the excitation electrode 11 and the measurement electrode 12) is a three-layer structure consisting of a central conductor wire 11a as a conductor member, an insulating layer 11b as an insulating member, and an outer layer conductor wire 11c as an outer layer conductor member. The outer layer conductor wire 11c is designed to be given the natural immersion potential of the installation location (water in the example of FIG. 1).

[0044] The measurement electrode 12 (at least one of the excitation electrode 11 and the measurement electrode 12) has a three-layer structure consisting of a central conductor wire 12a as a conductor member, an insulating layer 12b as an insulating member, and an outer layer conductor wire 12c as an outer layer conductor member. The outer layer conductor wire 12c is configured to be given the natural immersion potential of the installation location (water in the example of Figure 1).

[0045] At the intersection (the portion where the excitation electrode 11 and the measurement electrode 12 are disposed close to each other), the outer layer conductor wire 11c and the insulating layer 11b of the excitation electrode 11 are removed to form an opening 11d that exposes the center conductor wire 11a. Opposite the opening 11d, the outer layer conductor wire 12c and the insulating layer 12b of the measurement electrode 12 are removed to form an opening 12d that exposes the center conductor wire 12a.

[0046] That is, the central conductor wire 11a of the excitation electrode 11 and the central conductor wire 12a of the measurement electrode 12 are disposed close to each other. The openings 11d and 12d are formed, for example, with widths that are approximately the same as the diameters of the central conductor wires 11a and 12a and lengths (longitudinal widths) of 1.00 mm.

[0047] The shapes and arrangement of the conductor member, insulating member, and outer-layer conductor member of at least one of the excitation electrode and the measurement electrode can be designed as desired. For example, the conductor member, insulating member, and outer-layer conductor member can be formed into thin plates and arranged side by side to form the excitation electrode and the measurement electrode, and the excitation electrode and the measurement electrode can be arranged close to each other (for example, close enough so that the conductor members face each other).

[0048] In addition, excitation electrodes and measurement electrodes can be constructed by stacking conductor members, insulating members, and outer layer conductor members of desired thicknesses, and the excitation electrodes and measurement electrodes can be brought close to each other in any desired state (for example, bringing the conductor members close to each other so that they face each other, or partially removing the insulating members and outer layer conductor members so that the conductor members face each other).

[0049] A natural immersion potential is applied to the outer layer conductor wires 11c and 12c of the excitation electrode 11 and the measurement electrode 12, and by maintaining the outer layer conductor wires 11c and 12c at the natural immersion potential, the spread of the natural immersion potential shown in Figure 4 can be limited, and the impedance of the medium between the excitation electrode and the measurement electrode can be measured with the natural immersion potential as the reference potential.

[0050] In other words, if the outer layer conductor wires 11c and 12c were not present, the voltage around the opening 11d would also change, causing the applied power line to widen, which could make it difficult to properly detect the potential difference at the intersection and make it difficult to identify the measurement point (for example, the area including the intersection).

[0051] In the impedance sensor of this embodiment, the outer layer conductor wires 11c and 12c are maintained at the natural immersion potential, so that the areas other than the opening 11d are maintained at ±0 V, making it possible to measure the potential difference (transfer of signals) within the range of the opening 11d, and the measurement area (for example, the area including the intersection) can be reliably identified to measure the impedance at the intersection, making it possible to accurately determine the degree of electrical conductivity (conductivity) of the solute 3 (see Figure 1) at the intersection.

[0052] In the above-described embodiment, the areas (longitudinal widths) of the openings 11d and 12d of the excitation electrode 11 and measurement electrode 12 are set to obtain a desired dynamic range. Also, the distance (inter-electrode distance) between the openings 11d of the excitation electrode 11 and the openings 12d of the measurement electrode 12 is set to obtain a desired dynamic range.

[0053] The relationship between the dynamic range and the area (width in the longitudinal direction) of the opening 11d and the opening 12d of the excitation electrode 11 and the measurement electrode 12 will be described with reference to FIG.

[0054] The distance between the excitation electrode 11 and the measurement electrode 12 (inter-electrode distance) was kept constant (2 mm), and the following five types of samples were prepared. A sample in which the width of the opening 11d of the excitation electrode 11 is 2 mm and the width of the opening 12d of the measurement electrode 12 is 2 mm (◯). A sample (●) in which the width of the opening 11d of the excitation electrode 11 is 2 mm and the width of the opening 12d of the measurement electrode 12 is 3 mm A sample in which the width of the opening 11d of the excitation electrode 11 is 3 mm and the width of the opening 12d of the measurement electrode 12 is 3 mm (◇). A sample (▲) in which the width of the opening 11d of the excitation electrode 11 is 4 mm and the width of the opening 12d of the measurement electrode 12 is 3 mm A sample (▼) in which the width of the opening 11d of the excitation electrode 11 is 4 mm and the width of the opening 12d of the measurement electrode 12 is 4 mm The relationship between signal intensity (%) and conductivity (μS / cm) was determined for each of the five samples.

[0055] 5, as the widths of openings 11d and 12d of excitation electrode 11 and measurement electrode 12 become narrower (as the longitudinal lengths become shorter and the areas become smaller), the slope of the increase in signal strength with respect to conductivity becomes smaller, and signal strength can be obtained up to high conductivities, thereby widening the measurement range. In other words, by narrowing the widths of openings 11d and 12d of excitation electrode 11 and measurement electrode 12, the dynamic range can be widened.

[0056] The relationship between the dynamic range and the distance between excitation electrode 11 and measurement electrode 12 (inter-electrode distance) will be described with reference to FIG.

[0057] The widths of the opening 11d of the excitation electrode 11 and the opening 12d of the measurement electrode 12 were set to a constant value (2 mm), and the following three types of samples were prepared. A sample with a 1 mm distance between the excitation electrode 11 and the measurement electrode 12 (△) A sample (▽) with an electrode distance of 2 mm between the excitation electrode 11 and the measurement electrode 12 A sample (□) with an electrode distance of 3 mm between the excitation electrode 11 and the measurement electrode 12 The relationship between signal intensity (%) and conductivity (μS / cm) was determined for each of the three types of samples.

[0058] 6, as the distance between excitation electrode 11 and measurement electrode 12 is increased, the slope of the increase in signal strength with respect to conductivity becomes smaller, and a signal strength that can measure high conductivities can be obtained, thereby widening the measurement range. In other words, by increasing the distance between excitation electrode 11 and measurement electrode 12, the dynamic range can be widened.

[0059] A desired dynamic range can be obtained by setting the thickness of the excitation electrode 11 and the measurement electrode 12 (central conductor wires 11a, 12a) to a desired state.

[0060] The impedance sensor described above measures impedance within the range of the exposed size of the central conductor wires 11a, 12a (the sizes of the openings 11d, 12d), and therefore the range of the electric field lines can be limited within any dynamic range by arbitrarily setting the areas of the openings 11d, 12d and the distance between the excitation electrode 11 and the measurement electrode 12. This makes it possible to reliably measure the conductivity of the solute 3 in the pure water 2 over a wide measurement range, and to determine the state of the solute 3 of any substance (for example, the concentration of the solute 3).

[0061] The outer layer conductor wire 11c of the excitation electrode 11 (measurement electrode 12) is, for example, a stainless steel tube having an outer diameter of about 0.30 mm (e.g., 0.25 mm to 0.35 mm) and an inner diameter of about 0.15 mm (e.g., 0.10 mm to 0.20 mm). The diameter of the insulating layer 11b is set to, for example, 0.09 mm.

[0062] Since an extremely thin stainless steel tube is used as the outer layer conductor wire 11c, the influence on the flow field in the measurement region can be minimized, and the risk of affecting the flow of the fluid can be reduced.

[0063] The excitation electrode 11 (measurement electrode 12) may be made by applying an insulating coating to a central conductor wire, coating the insulating coating with a resin mixed with carbon, and forming an opening of the desired area with a laser.

[0064] In the impedance sensor of the present invention, the excitation electrodes 11 and measurement electrodes 12 arranged in a grid pattern can be arranged in multiple layers, thereby making it possible to provide an impedance sensor in which grid-like structures are arranged in multiple layers.

[0065] Another embodiment of the present invention will be described with reference to FIGS.

[0066] Figure 7 shows a schematic configuration of the main parts of an impedance sensor according to another embodiment in which the excitation electrode 11 has a three-layer structure, Figure 8 shows a schematic configuration of the main parts of an impedance sensor according to another embodiment in which the measurement electrode 12 has a three-layer structure, and Figure 9 shows a schematic configuration of the main parts of an impedance sensor according to another embodiment in which two measurement electrodes 12 are provided on either side of the excitation electrode 11.

[0067] 7(a), the excitation electrode 11 is a three-layer member consisting of a center conductor wire 11a, an insulating layer 11b, and an outer conductor wire 11c, and the outer conductor wire 11c is configured to be applied with the natural immersion potential of the installation location. The measurement electrode 12 has a two-layer structure consisting of a center conductor wire 12a and an insulating layer 12b. This allows for an impedance sensor having a three-layer excitation electrode 11 and a two-layer measurement electrode 12.

[0068] In the embodiment shown in Figure 7(b), the excitation electrode 11 is a three-layer member consisting of a center conductor wire 11a, an insulating layer 11b, and an outer layer conductor wire 11c, and the outer layer conductor wire 11c is configured to be applied with the natural immersion potential of the installation location. The measurement electrode 12 has a single-layer structure consisting of only the center conductor wire 12a. This allows for an impedance sensor having a three-layer excitation electrode 11 and a single-layer measurement electrode 12.

[0069] In the embodiment shown in Figure 8(a), the measurement electrode 12 is a three-layer member consisting of a center conductor wire 12a, an insulating layer 12b, and an outer conductor wire 12c, and the outer conductor wire 12c is configured to be applied with the natural immersion potential of the installation location. The excitation electrode 11 has a two-layer structure consisting of a center conductor wire 11a and an insulating layer 11b. This allows for an impedance sensor having a two-layer excitation electrode 11 and a three-layer measurement electrode 12.

[0070] In the embodiment shown in Figure 8(b), the measurement electrode 12 is a three-layer member consisting of a center conductor wire 12a, an insulating layer 12b, and an outer conductor wire 12c, and the outer conductor wire 12c is designed to be applied with the natural immersion potential of the installation location. The excitation electrode 11 has a single-layer structure consisting of only the center conductor wire 11a. This allows for an impedance sensor having a single-layer excitation electrode 11 and a three-layer measurement electrode 12.

[0071] 9, measurement electrodes 12 are arranged in two layers, and one excitation electrode 11 is arranged between the measurement electrodes 12. By arranging the measurement electrodes 12 in two layers with the excitation electrode 11 sandwiched between them and changing the distance (distance d and distance D) between each measurement electrode 12 and excitation electrode 11, it is possible to simultaneously measure impedances in different dynamic ranges, and to measure high conductivities while also measuring low conductivities in detail.

[0072] The impedance sensor described above can measure the impedance of the medium between the excitation electrode and the measurement electrode with the natural immersion potential as the reference potential by limiting the extent of the natural immersion potential by maintaining the outer layer conductor wires 11c, 12c at the natural immersion potential of the pure water 2. This makes it possible to reliably measure the conductivity of the solute 3 in the pure water 2 over a wide range and accurately determine the concentration of the solute 3 instantaneously and locally. [Industrial Applicability]

[0073] The present invention can be used in the industrial field of impedance sensors that measure the impedance of any substance in a fluid (the impedance of a fluid in which any substance is dissolved). [Explanation of symbols]

[0074] 1 container 2 Pure water 3 Solute 4 fluid 6 Impedance Sensor 11 Excitation electrode 11a Center conductor wire 11b Insulating layer 11c Outer layer conductor wire 11d opening 12 Measurement electrode 12a Center conductor wire 12b Insulating layer 12c outer layer conductor wire 12d opening 14 Switch 15 Power supply

Claims

1. an excitation electrode that applies a predetermined potential; a measurement electrode provided adjacent to the excitation electrode, immersed in the fluid, and configured to measure a potential by transmitting and receiving a signal between the measurement electrode and the excitation electrode; At least one of the excitation electrode and the measurement electrode is The insulating member includes a conductor member, an insulating member, and an outer layer conductor member. The outer layer conductor member is The excitation electrode and the measurement electrode are immersed in a fluid to which the natural immersion potential of the fluid is applied. An impedance sensor characterized by:

2. 2. The impedance sensor according to claim 1, The conductor member, the insulating member, and the outer layer conductor member are arranged in a stacked manner. An impedance sensor characterized by:

3. 3. The impedance sensor according to claim 2, The excitation electrode and the measurement electrode are adjacent to each other. An impedance sensor characterized by:

4. 4. The impedance sensor according to claim 3, the excitation electrode and the measurement electrode are elongated, the excitation electrode and the measurement electrode are provided in close proximity to each other by being provided in a crossing relationship; The conductor member is a central conductor wire, and an insulating layer is disposed on the central conductor wire as the insulating member. an outer layer conductor wire is disposed on the insulating layer as the outer layer conductor member; At least one of the excitation electrode and the measurement electrode is The member has a triple structure of the central conductor wire, the insulating layer, and the outer layer conductor wire, and the central conductor wire is exposed at the intersection, The impedance is measured by measuring the potential with the measurement electrode. An impedance sensor characterized by:

5. 5. The impedance sensor according to claim 4, One of the excitation electrode and the measurement electrode is The core conductor wire is a triple-layered member consisting of the insulating layer and the outer conductor wire. An impedance sensor characterized by:

6. 6. The impedance sensor according to claim 5, The other of the excitation electrode and the measurement electrode is The member has a double structure of the central conductor wire and the insulating layer, and the central conductor wire is exposed at the intersection. An impedance sensor characterized by:

7. 6. The impedance sensor according to claim 5, The other of the excitation electrode and the measurement electrode is The central conductor wire is a single member. An impedance sensor characterized by:

8. 5. The impedance sensor according to claim 4, Both the excitation electrode and the measurement electrode are The core conductor wire is a triple-layered member consisting of the insulating layer and the outer conductor wire. An impedance sensor characterized by:

9. The impedance sensor according to any one of claims 4 to 8, The area where the central conductor wire is exposed at the intersection of the triple-layered member is set to obtain a desired dynamic range. An impedance sensor characterized by:

10. The impedance sensor according to any one of claims 4 to 9, The distance between the axes of the excitation electrode and the measurement electrode is set to obtain a desired dynamic range. An impedance sensor characterized by:

11. The impedance sensor according to any one of claims 4 to 10, A plurality of the excitation electrodes and the measurement electrodes are provided, and the excitation electrodes and the measurement electrodes are arranged in a grid pattern by being spaced apart from one another. An impedance sensor characterized by:

12. 12. The impedance sensor according to claim 11, The excitation electrodes and the measurement electrodes are arranged in a grid pattern. It is arranged over several layers An impedance sensor characterized by:

13. The impedance sensor according to any one of claims 4 to 12, The measurement electrodes are arranged in two layers, and the excitation electrodes are arranged between the layers of the measurement electrodes. An impedance sensor characterized by:

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