JP2012242095A - Sensor device - Google Patents

Abstract

[PROBLEMS] To provide a sensor device capable of measuring a change in a state of an object to be measured after a reinforcing bar is constructed and before corrosion starts and utilizing the obtained information for planned maintenance of a concrete structure. To do.
A sensor device according to the present invention includes a first electrode, a second electrode provided apart from the first electrode, a first electrode, and a second electrode. 4 and an insulating film 8 having a through-hole penetrating in the thickness direction, and a functional element 51 having a function of measuring a potential difference between the first electrode 3 and the second electrode 4. Based on the potential difference measured by the functional element 51, the state of the measurement target part can be measured.
[Selection] Figure 3

Description

  The present invention relates to a sensor device.

As a sensor device, for example, a device that measures the corrosion state of a reinforcing bar in concrete is known (see, for example, Patent Document 1).
The concrete in the concrete structure immediately after construction usually exhibits strong alkalinity. Therefore, the reinforcing bars in the concrete structure immediately after construction are stable because a passive film is formed on the surface. However, in concrete structures that have been affected by acid rain or exhaust gas after construction, the concrete is gradually acidified, and the steel bars are corroded.
For example, in the apparatus described in Patent Document 1, a probe having a reference electrode and a counter electrode is embedded in concrete, and potential change due to corrosion of the reinforcing bar and polarization resistance are measured, thereby predicting corrosion of the reinforcing bar.

  In such an apparatus, the natural potential of the reinforcing bar used as the working electrode is measured by the reference electrode and the counter electrode embedded in the concrete. However, when the moisture on the reinforcing bar surface is insufficient, the corrosion reaction does not proceed. For this reason, even if there is a corroded area in the reinforcing bar, if the surface of the reinforcing bar has insufficient moisture, a potential difference (gradient) between the corroded area and the non-corroded area does not occur. For this reason, the apparatus described in Patent Document 1 is greatly affected by fluctuations in moisture in the concrete, the natural potential (gradient) of the reinforcing bars varies, and it is difficult to accurately predict the corrosion of the reinforcing bars. It was.

JP-A-6-222033

  The object of the present invention is to measure the state change of a measurement object during the period from when a reinforcing bar is constructed to when corrosion starts, and to use the obtained information for the planned maintenance of concrete structures. To provide an apparatus.

Such an object is achieved by the present invention described below.
The sensor device of the present invention includes a first electrode,
A second electrode spaced apart from the first electrode;
An insulating film provided so as to cover at least one of the first electrode and the second electrode, and having a through hole or a through groove penetrating in the thickness direction;
A functional element having a function of measuring a potential difference between the first electrode and the second electrode;
Based on the potential difference measured by the functional element, the state of the measurement target region can be measured.

According to the sensor device configured as described above, due to the capillary condensation effect by the through hole or the through groove of the insulating film, at least one of the first electrode and the second electrode at a lower relative humidity. Moisture can be condensed. Therefore, liquid water can be stably present on the electrode.
For this reason, even if the relative humidity of the measurement target portion changes with changes in the humidity and temperature of the external environment, fluctuations in the amount of water on the electrode can be prevented. As a result, it is possible to prevent the natural potential of the electrode from fluctuating due to changes in the humidity and temperature of the external environment, and to measure the state of the measurement target site with high accuracy.

In the sensor device of the present invention, the insulating film is formed of a porous body having a continuous hole in which adjacent holes communicate with each other, and the continuous hole forms at least a part of the through hole. preferable.
Thereby, the capillary condensation effect by the through-hole of an insulating film can be produced effectively.
In the sensor device according to the aspect of the invention, it is preferable that a recess is formed on a surface of the insulating film opposite to the first electrode and the second electrode.
Thereby, for example, when the measurement target site is concrete, even if the aggregate in the concrete contacts the insulating film on the first electrode or the second electrode, there is a gap between the insulating film and the aggregate. Can be generated. Therefore, the components in the concrete (water, Ca ions, etc.) are supplied to the first electrode or the second electrode through the gap to stabilize the amount of water on the first electrode and the second electrode. be able to.

In the sensor device of the present invention, concave portions are formed on the surfaces of the first electrode and the second electrode,
The insulating film preferably has a recess formed following the recess.
Thereby, the recess can be formed on the insulating film relatively easily.
In the sensor device of the present invention, it is preferable that the through hole or the through groove is patterned by etching.
Thereby, it is possible to relatively easily form an insulating film having a through-hole or a through-groove that can cause a capillary aggregation effect.

In the sensor device of the present invention, it is preferable that the insulating film is provided so as to cover both the first electrode and the second electrode.
Thereby, even if the relative humidity of a measurement object part changes with changes in the humidity and temperature of the external environment, it is possible to prevent fluctuations in the amount of water on the first electrode and the second electrode. As a result, it is possible to prevent the natural potentials of the first electrode and the second electrode from fluctuating due to changes in the humidity and temperature of the external environment, and to measure the state of the measurement target portion with high accuracy.
In the sensor device of the present invention, it is preferable that the insulating film has alkali resistance.
Thereby, even if it is a case where a measurement object part is concrete, the endurance of an insulating film can be made excellent. Therefore, the state of concrete can be measured stably over a long period of time.

In the sensor device of the present invention, does at least one of the first electrode and the second electrode form a first passive film on a surface in accordance with an environmental change of the measurement target site? Or it is preferable to be comprised with the metal material which lose | disappears the 1st passive film which existed on the surface.
As a result, the potential difference between the first electrode and the second electrode changes abruptly depending on the presence or absence of the passive film accompanying the change in pH of the measurement target site. Therefore, it is possible to accurately detect whether the pH of the measurement target site is equal to or lower than the set value.
In addition, the potential difference between the first electrode and the second electrode changes sharply due to the disappearance of the passive film accompanying the change in the chloride ion concentration at the site to be measured. Therefore, it is possible to accurately detect whether or not the chloride ion concentration at the measurement target site is equal to or lower than the set value.

In the sensor device of the present invention, the metal material is preferably iron or an iron-based alloy.
Iron or iron-based alloys (iron-based materials) are relatively inexpensive and easily available. Further, for example, when the sensor device is used for measuring the state of a concrete structure, at least one of the first electrode and the second electrode can be made of the same material as the reinforcing bar in the concrete structure. In addition, the corrosion state of the reinforcing bars in the concrete structure can be detected effectively.

In the sensor device of the present invention, the functional element detects whether the pH or chloride ion concentration of the measurement target site is equal to or lower than a set value based on a potential difference between the first electrode and the second electrode. It is preferable to have a function of
Thereby, the state change accompanying the pH change or chloride ion concentration change of a measuring object is detectable.
The sensor device of the present invention has an antenna and a communication circuit having a function of supplying power to the antenna,
It is preferable that the functional element also has a function of driving and controlling the communication circuit.
Thereby, a measurement result can be transmitted to the exterior of a measurement object by radio.

It is a figure which shows an example of the use condition of the sensor apparatus which concerns on 1st Embodiment of this invention. It is a block diagram which shows schematic structure of the sensor apparatus shown in FIG. It is a top view for demonstrating the 1st electrode shown in FIG. 2, a 2nd electrode, and a functional element. It is sectional drawing for demonstrating the 1st electrode shown in FIG. 2, and a 2nd electrode (AA sectional view taken on the line in FIG. 3). It is sectional drawing for demonstrating the functional element shown in FIG. 2 (BB sectional drawing in FIG. 3). FIG. 3 is an enlarged cross-sectional view illustrating an example of a configuration of a first electrode and an insulating film illustrated in FIG. 2. FIG. 3 is a circuit diagram showing a differential amplifier circuit provided in the functional element shown in FIG. 2. FIG. 3 is a circuit diagram showing a differential amplifier circuit provided in the functional element shown in FIG. 2. It is a figure which shows an example of the use condition of the sensor apparatus which concerns on 2nd Embodiment of this invention. It is a top view for demonstrating the 1st electrode of the sensor apparatus which concerns on 3rd Embodiment of this invention, a 2nd electrode, and a functional element. It is sectional drawing for demonstrating the 1st electrode shown in FIG. 10, and a 2nd electrode (AA sectional view taken on the line in FIG. 3). It is sectional drawing for demonstrating the 1st electrode of the sensor apparatus which concerns on 4th Embodiment of this invention, and a 2nd electrode.

Hereinafter, a preferred embodiment of a sensor device of the present invention will be described with reference to the accompanying drawings.
<First Embodiment>
First, a first embodiment of the present invention will be described.
1 is a diagram showing an example of a usage state of a sensor device according to a first embodiment of the present invention, FIG. 2 is a block diagram showing a schematic configuration of the sensor device shown in FIG. 1, and FIG. 3 is shown in FIG. FIG. 4 is a plan view for explaining the first electrode, the second electrode, and the functional element, and FIG. 4 is a cross-sectional view for explaining the first electrode and the second electrode shown in FIG. 2 (A in FIG. 3). 5 is a cross-sectional view for explaining the functional element shown in FIG. 2 (cross-sectional view taken along the line BB in FIG. 3), and FIG. 6 shows the first electrode shown in FIG. FIG. 7 and FIG. 8 are circuit diagrams showing differential amplifier circuits provided in the functional element shown in FIG. 2, respectively.
In the following, a case where the sensor device of the present invention is used for quality measurement of a concrete structure will be described as an example.

A sensor device 1 shown in FIG. 1 measures the quality of a concrete structure 100.
The concrete structure 100 has a plurality of reinforcing bars 102 embedded in a concrete 101. The sensor device 1 is embedded in the vicinity of the reinforcing bar 102 in the concrete 101 of the concrete structure 100. Note that when the concrete structure 100 is placed, the sensor device 1 may be fixed and embedded in the reinforcing bar before placing the concrete 101, or may be embedded in the concrete 101 hardened after placing.

  The sensor device 1 includes a main body 2 and a first electrode 3 and a second electrode 4 provided on the main body 2. In addition, the sensor device 1 has an insulating film 8 that covers the first electrode 3 and the second electrode 4 (see FIG. 3). The first electrode 3 and the second electrode 4 are exposed on the surface of the main body 2 through holes 82 described later of the insulating film 8. In FIG. 1, for convenience of explanation, illustration of an insulating film 8 described later is omitted.

In this embodiment, the 1st electrode 3 and the 2nd electrode 4 are installed so that the distance from the outer surface of the concrete structure 100 may become equal mutually in the outer surface side of the concrete structure 100 rather than the reinforcing bar 102. ing. Further, the first electrode 3 and the second electrode 4 are respectively installed such that the electrode surfaces are parallel or substantially parallel to the outer surface of the concrete structure 100. And the 1st electrode 3 and the 2nd electrode 4 are comprised so that the electrical potential difference between these may change with the pH change of the measurement object site | part of the concrete 101. FIG. The first electrode 3 and the second electrode 4 will be described in detail later.
As shown in FIG. 2, the sensor device 1 includes a functional element 51 electrically connected to the first electrode 3 and the second electrode 4, a power source 52, a temperature sensor 53, and a communication circuit 54. And an antenna 55 and an oscillator 56, which are housed in the main body 2.

Hereinafter, each part which comprises the sensor apparatus 1 is demonstrated sequentially.
(Body)
The main body 2 has a function of supporting the first electrode 3, the second electrode 4, the functional element 51, and the like.
As shown in FIGS. 4 and 5, the main body 2 has a substrate 21 that supports the first electrode 3, the second electrode 4, and the functional element 51. The substrate 21 also supports the power supply 52, the temperature sensor 53, the communication circuit 54, the antenna 55, and the oscillator 56. However, in FIGS. 3 to 5, for convenience of explanation, the power supply 52, the temperature sensor 53, and the communication circuit 54 are used. The antenna 55 and the oscillator 56 are not shown.

The substrate 21 has an insulating property. The substrate 21 is not particularly limited, and for example, an alumina substrate, a resin substrate, or the like can be used.
On this substrate 21, an insulating layer 23 made of an insulating resin composition such as a solder resist is provided. Then, the first electrode 3, the second electrode 4, and the functional element 51 are mounted on the substrate 21 through the insulating layer 23.

As shown in FIG. 5, the functional element 51 (integrated circuit chip) is held on the substrate 21, and the conductor portions 61 and 62 (electrode pads) of the functional element 51 are the first electrode 3 and the second electrode. 4 is connected.
The conductor portion 61 electrically connects the first electrode 3, the conductor portions 516a and 516d, and the gate electrode of the transistor 514a. The conductor 62 electrically connects the second electrode 4, the conductors 516b and 516e, and the gate electrode of the transistor 514b. Since the first electrode 3 and the second electrode 4 are connected to the gate electrodes of the transistors 514a and 514b, respectively, they are in a floating state. 515a and 515b are interlayer insulating films of the integrated circuit, and 25 is a protective film of the integrated circuit.

The main body 2 has a function of housing the functional element 51, the power source 52, the temperature sensor 53, the communication circuit 54, the antenna 55, and the oscillator 56.
In particular, the main body 2 is configured to store the functional element 51, the power source 52, the temperature sensor 53, the communication circuit 54, the antenna 55, and the oscillator 56 in a liquid-tight manner.
Specifically, as shown in FIGS. 4 and 5, the main body 2 has a sealing portion 24. The sealing unit 24 has a function of sealing the functional element 51, the power source 52, the temperature sensor 53, the communication circuit 54, the antenna 55, and the oscillator 56. Thereby, when the sensor apparatus 1 is installed in the presence of moisture or concrete, it is possible to prevent the functional element 51, the power source 52, the temperature sensor 53, the communication circuit 54, the antenna 55, and the oscillator 56 from being deteriorated.

  Here, the sealing portion 24 has an opening 241, and the first electrode 3 and the second electrode 4 are exposed from the opening 241, and the portions other than the first electrode 3 and the second electrode 4 are exposed. It is provided so as to cover each part (see FIGS. 3 and 4). Thereby, the sensor device 1 can perform the measurement while the sealing portion 24 prevents the deterioration of the respective portions other than the first electrode 3 and the second electrode 4. The opening 241 may be formed so as to expose at least a part of the first electrode 3 and at least a part of the second electrode 4. The first electrode 3 and the second electrode 4 are exposed from the opening 241 while being covered with an insulating film 8 to be described later.

Examples of the constituent material of the sealing portion 24 include thermoplastic resins such as acrylic resins, urethane resins, and olefin resins, epoxy resins, melamine resins, thermosetting resins such as phenol resins, and the like. Various resin materials etc. are mentioned, Among these, it can use combining 1 type (s) or 2 or more types.
In addition, the sealing part 24 should just be provided as needed, and can also be abbreviate | omitted.

(First electrode, second electrode)
As shown in FIG. 4, each of the first electrode 3 and the second electrode 4 is provided on the outer surface of the main body 2 (more specifically, on the substrate 21). In particular, the first electrode 3 and the second electrode 4 are provided on the same plane. Therefore, it is possible to prevent the difference in installation environment between the first electrode 3 and the second electrode 4 from occurring.
Further, the first electrode 3 and the second electrode 4 are separated to such an extent that they are not affected by the potential (for example, several mm).

In the present embodiment, each of the first electrode 3 and the second electrode 4 has a thin film shape. Moreover, the planar view shape of the 1st electrode 3 and the 2nd electrode 4 has comprised the square, respectively. Further, the first electrode 3 and the second electrode 4 have the same shape and area in plan view.
In the present embodiment, a recess 31 is formed on the surface of the first electrode 3, and similarly, a recess 41 is formed on the surface of the second electrode 4. If such concave portions 31 and 41 are formed, the concave portion 81 can be relatively easily formed on the insulating film 8 described later.
Each of the recesses 31 and 41 can be formed by etching, for example.

  The first electrode 3 is composed of a first metal material (hereinafter also simply referred to as “first metal material”) that forms a passive film (first passive film). As for the 1st electrode 3 comprised in this way, a passive film is formed or destroyed by the change of pH. In such a state where a passive film is formed on the first electrode 3 (passivated state), the first electrode 3 is inactive (noble), and the natural potential becomes high (noble). On the other hand, the first electrode 3 is active (base) in a state where the passive film is destroyed (a state where it is lost). Therefore, the potential of the first electrode 3 changes sharply depending on the presence or absence of a passive film accompanying a change in pH.

The first metal material is not particularly limited as long as a passive film is formed, and examples thereof include Fe, Ni, Mg, Zn, and alloys containing these.
For example, Fe forms a passive film when the pH is greater than 9. Further, FeAl (Al 0.8%) based carbon steel forms a passive film when the pH is higher than 4. Ni forms a passive film when the pH is 8-14. Mg forms a passive film when the pH is higher than 10.5. Zn forms a passive film when the pH is 6-12.

  Among these, the first metal material is preferably Fe or an alloy containing Fe (Fe-based alloy), that is, an iron-based material (specifically, carbon steel, alloy steel, SUS, etc.). Iron-based materials are cheap and easy to obtain. Further, when the sensor device 1 is used for measuring the state of the concrete structure 100 as in this embodiment, the first metal material can be the same as or similar to the rebar 102 of the concrete structure 100. Yes, the corrosive environment state of the reinforcing bar 102 can be detected effectively. For example, when the first electrode 3 is made of Fe, it can be determined whether the pH is 9 or more.

  On the other hand, the second electrode 4 is composed of a second metal material different from the first metal material (hereinafter also simply referred to as “second metal material”). The second electrode 4 configured as described above has no formation or destruction (disappearance) of the nonconductive film when the potential of the first electrode 3 changes depending on the presence or absence of the passive film, as described above, and the There is no significant potential change. Therefore, as described above, when the potential of the first electrode 3 changes depending on the presence or absence of the passive film, the potential difference between the first electrode 3 and the second electrode 4 changes sharply. Therefore, it is possible to accurately detect whether the pH of the installation environment of the first electrode 3 and the second electrode 4 (in the present embodiment, the vicinity of the reinforcing bar 102 of the concrete 101) is equal to or lower than the set value.

The second metal material is not particularly limited as long as it is a metal material different from the first metal material and can function as an electrode, and various metal materials can be used.
Moreover, as long as the second metal material is a metal material different from the first metal material described above, a passive film may be formed, or a passive film may not be formed. .
In the case where the second metal material forms a passive film (second passive film), examples of the second metal material include the metals exemplified as the first metal material.

  In a preferred embodiment of the present invention, the lower limit of the pH range in which the first metallic material forms a passive film is the first pH (first passive pH), and the second metallic material is passive. When the lower limit of the pH range for forming the film is the second pH (second passivating pH), the first pH and the second pH are different from each other. That is, the first metal material forms a passive film when the pH is higher than the first pH, and the second metal material is higher than the second pH different from the first pH. A passive film is formed when the pH is reached. Thereby, it is possible to accurately detect whether or not the pH of the environment in which the first electrode 3 and the second electrode 4 are installed is lower than the first pH and lower than the second pH.

  In this case, the first pH is preferably 8 or more and 10 or less, and the second pH is preferably 7 or less. Thereby, by detecting whether it is below 1st pH, it can know beforehand that the installation environment of the 1st electrode 3 and the 2nd electrode 4 is approaching a neutral state. For this reason, when the sensor device 1 is used for measuring the state of the concrete structure 100 as in the present embodiment, measures for preventing corrosion of the reinforcing bars 102 can be taken in advance. Moreover, it can also be known that the installation environment of the 1st electrode 3 and the 2nd electrode 4 has become an acidic state by detecting whether it is below 2nd pH.

  In this case, the second metal material is preferably an alloy containing Fe (Fe-based alloy), that is, an iron-based material. Iron-based materials are cheap and easy to obtain. Further, when the sensor device 1 is used for measuring the state of the concrete structure 100 as in this embodiment, the first metal material can be the same material as the reinforcing bar 102, and the second metal material can be By using the same kind of material as the reinforcing steel 102 (Fe-based alloy), the corrosion state of the reinforcing steel 102 can be detected effectively.

On the other hand, when the second metal material does not form a passive film, examples of the second metal material include Pt and Au. When the second metal material does not form a passive film, when the installation environment of the first electrode 3 and the second electrode 4 changes from a strong alkali state to a strong acid state, the change is made in one step. It can be detected with high accuracy.
In this case, it is preferable that the first metal material forms a passive film when the pH becomes 3 or more and 5 or less or a pH higher than 8 or 10 and less. By detecting whether the pH is 3 or more and 5 or less, it can be known that the installation environment of the first electrode 3 and the second electrode 4 has become an acidic state. Further, by detecting whether the pH is 8 or more and 10 or less, it can be known in advance that the installation environment of the first electrode 3 and the second electrode 4 is approaching a neutral state.

  According to another aspect of the present invention, when the second metal material forms a passive film, the chloride ion concentration lower limit value at which the passive film destruction of the first metal material starts is set to the first chloride. The first chloride ion concentration and the second chloride ion concentration when the lower limit value of the chloride ion concentration at which the passive film destruction of the second metal material starts is the second chloride ion concentration. Are different from each other. That is, when the first metal material becomes larger than the first chloride ion concentration, the passive film breaks down, and the second metal material has the second concentration different from the first chloride ion concentration. When the chloride ion concentration is exceeded, the passive membrane begins to break. Thereby, whether the chloride ion concentration of the environment in which the first electrode 3 and the second electrode 4 are installed is less than the first chloride ion concentration and less than the second chloride ion concentration, respectively. It can be detected accurately.

In this case, the first chloride ion concentration is 1.0 kg / m ³ or more and 1.5 kg / m ³ or less (preferably about 1.2 kg / m ³ ), and the second chloride ion concentration is the first chloride ion concentration. It is preferably greater than 1 chloride ion concentration. Thereby, it is possible to know whether or not chloride ions have entered the installation environment of the first electrode 3 and the second electrode 4 by detecting whether or not the concentration is lower than the first chloride ion concentration. For example, carbon steel (SD345) having a first chloride ion concentration of about 1.2 kg / m ³ is used for the first metal material, and a second chloride ion concentration of about 20 kg / m 2 is used for the second metal material. using the m is ³ SUS304. The second electrode 4 configured in this way is passive when the potential of the first electrode 3 changes when the chloride ion concentration exceeds 1.2 kg / m ³ and the passive film breakage starts. There is no destruction (disappearance) of the film, and there is no sudden potential change. Therefore, when the potential of the first electrode 3 changes depending on the presence or absence of the passive film, the potential difference between the first electrode 3 and the second electrode 4 changes sharply. Therefore, it is accurately determined whether or not the chloride ion concentration in the installation environment of the first electrode 3 and the second electrode 4 (in the present embodiment, near the reinforcing bar 102 of the concrete 101) exceeds the set value 1.2 kg / m ^3. Can be detected. SUS316 and SUS329J4L, which are excellent in resistance to the second metal material, can also be used.
For this reason, when the sensor device 1 is used for measuring the state of the concrete structure 100 as in this embodiment, CO ₂ (neutralization) and chlorine ions that enter the concrete 101 from the outside are introduced into the concrete structure. It can be detected before reaching the reinforcing bar 102 in the object 100. Therefore, measures for preventing corrosion can be taken before the reinforcing bars 102 corrode.

  The first electrode 3 and the second electrode 4 are formed by chemical vapor deposition (CVD) such as plasma CVD, thermal CVD, and laser CVD, vacuum vapor deposition, sputtering (low temperature sputtering), and ion plating, respectively. It can be formed by dry plating methods such as electroplating, immersion plating, electroless plating, and other wet plating methods, thermal spraying methods, sol-gel methods, MOD methods, metal foil bonding, and the like.

(Insulating film)
The insulating film 8 is provided so as to cover both the first electrode 3 and the second electrode 4. The insulating film 8 is composed of a porous body 83 having a plurality of pores 82 as shown in FIG. The plurality of holes 82 form continuous holes (pores) in which the adjacent holes 82 communicate with each other, and the continuous holes open on the surface of the insulating film 8. Here, the continuous holes constitute a through hole penetrating in the thickness direction of the insulating film 8.
Through such continuous holes, moisture at the site to be measured can be supplied onto the first electrode 3 and the second electrode 4.
In particular, due to the capillary condensation effect by such continuous pores (pores), moisture can be condensed on the first electrode 3 and the second electrode 4 at lower relative humidity.

In the present embodiment, since the insulating film 8 is composed of the porous body 83 having the continuous pores as described above, the capillary condensation effect by each continuous pore through hole of the insulating film 8 is effectively generated. Can do.
Therefore, liquid water can be stably present on the first electrode 3 and the second electrode 4. That is, if the insulating film 8 is omitted, even on the first electrode 3 and the second electrode 4 even at a low relative humidity such that no condensation occurs on the first electrode 3 and the second electrode 4. Each can be condensed and liquid water can be present.

  For this reason, even if the relative humidity in the concrete 101 changes with changes in the humidity and temperature of the external environment, fluctuations in the amount of water on the first electrode 3 and the second electrode 4 are prevented. be able to. As a result, it is possible to prevent the natural potential of the first electrode 3 and the second electrode 4 from fluctuating due to changes in humidity and temperature of the external environment, and to measure the state of the measurement target portion of the concrete 101 with high accuracy. it can.

In addition, the average diameter of the plurality of holes 82 is not particularly limited as long as it is within a range in which the capillary condensation effect can be generated as described above. For example, the average diameter is preferably 2 nm or more and 50 nm or less. That is, the holes 82 are preferably mesopores.
Further, the porosity of the insulating film 8 is not particularly limited as long as it is within the range where the capillary condensation effect can be generated as described above, but is preferably 10% or more and 90% or less, for example.

In addition, the constituent material of the insulating film 8 is not particularly limited as long as it has insulating properties. From the viewpoint of excellent insulating properties and durability, for example, oxides, nitrides, and fluorides of metals and silicon are used. Etc. (ceramic material) is preferably used. A resin material can also be used as a constituent material of the insulating film 8.
The insulating film 8 preferably has alkali resistance. For example, as the constituent material of the insulating film 8, it is preferable to use a material excellent in alkali resistance such as SiO ₂ or Si ₃ N ₄ . Thereby, even if it is a case where a measurement object site | part is the concrete 101, durability of the insulating film 8 can be made excellent. Therefore, the state of the concrete 101 can be measured stably over a long period.

In the present embodiment, a plurality of recesses 81 are formed on the surface of the insulating film 8 opposite to the first electrode 3 and the second electrode 4, that is, the surface. Thereby, even if the aggregate in the concrete 101 contacts the insulating film 8 on the first electrode 3 or the second electrode 4, a gap can be generated between the insulating film 8 and the aggregate. . Therefore, components (water, Ca ions, etc.) in the concrete 101 are supplied to the first electrode 3 or the second electrode 4 through the gaps, and the amount of water on the first electrode 3 and the second electrode 4. Can be stabilized.
The recess 81 is formed following the recess 31 of the first electrode 3 and the recess 41 of the second electrode 4 described above.
The average diameter (average width) of the recess 81 is not particularly limited as long as it is smaller than the aggregate size and larger than the average diameter of the air holes 82 described above.

  The average thickness of the insulating film 8 is not particularly limited, but is preferably 5 nm or more and 1000 nm or less, for example. As a result, the insulating film 8 having continuous through-holes capable of producing the capillary aggregation effect as described above can be formed relatively easily. On the other hand, if the average thickness is too thin, it is difficult to form continuous pores (through-holes) that can cause the capillary aggregation effect as described above. On the other hand, if the average thickness is too thick, It becomes difficult to supply moisture and the like to the first electrode 3 and the second electrode 4 through the holes.

  Such an insulating film 8 is not particularly limited, and can be formed using a known porous film forming method. For example, when the insulating film 8 is composed of a metal oxide, a precursor solution in which a metal oxo species that is a precursor of the metal oxide and a polystyrene-based surfactant are dissolved in a polar solvent is spin-coated, an ink jet method, or the like The insulating film 8 can be formed by forming a film by the coating method, drying, and baking.

The shape of the plurality of holes 82 shown in FIG. 6 is an example, and is not limited to the illustrated one as long as the continuous holes of the insulating film 8 can exhibit the capillary condensation effect as described above. The insulating film 8 can be composed of various known porous bodies having continuous pores.
In the present embodiment, one insulating film 8 is provided so as to cover the first electrode 3 and the second electrode 4, but the insulating film covering the first electrode 3 and the second electrode 4 are provided. An insulating film covering the surface may be provided separately. In this case, the configurations (thickness, material, porosity, etc.) of the two insulating films may be the same or different from each other.

(Functional element)
The functional element 51 is embedded in the main body 2 described above. The functional element 51 may be provided on the same surface as the first electrode 3 and the second electrode 4 with respect to the substrate 21 of the main body 2 described above or on the opposite side.
The functional element 51 has a function of measuring a potential difference between the first electrode 3 and the second electrode 4. Thereby, based on the electric potential difference of the 1st electrode 3 and the 2nd electrode 4, it can be detected whether the pH of the installation environment of the 1st electrode 3 and the 2nd electrode 4 is below a setting value. .
Further, based on the potential difference between the first electrode 3 and the second electrode 4, the functional element 51 determines whether the pH or chloride ion concentration of the measurement target portion of the concrete structure 100 that is the measurement target is less than the set value. It also has a function of detecting whether or not. Thereby, the state change accompanying the pH change or chloride ion concentration change of the concrete structure 100 is detectable.

Such a functional element 51 is, for example, an integrated circuit. More specifically, the functional element 51 is, for example, an MCU (micro control unit), and includes a CPU 511, an A / D conversion circuit 512, and a differential amplifier circuit 514 as shown in FIG.
More specifically, as shown in FIG. 5, the functional element 51 includes a substrate 513, a plurality of transistors 514a, 514b, and 514c provided on the substrate 513, and an interlayer insulation covering the transistors 514a, 514b and 514c. Films 515a and 515b, conductor portions 516a, 516b, 516c, 516d, 516e, and 516f that constitute wiring and conductor posts, a protective film 25, and conductor portions 61 and 62 that constitute electrode pads are included.

The substrate 513 is, for example, an SOI substrate, on which a CPU 511 and an A / D conversion circuit 512 are formed. By using an SOI substrate as the substrate 513, the transistors 514a to 514c can be SOI MOSFETs.
Each of the plurality of transistors 514a, 514b, and 514c is, for example, a field effect transistor (FET), and constitutes a part of the differential amplifier circuit 514.

As shown in FIG. 7, the differential amplifier circuit 514 includes three transistors 514a to 514c and a current mirror circuit 514d.
Further, the differential amplifier circuit 514 includes operational amplifiers 201 and 202 and an operational amplifier 203 as shown in FIG.
The operational amplifier 201 detects the potential of the first electrode 3 with reference to the comparison electrode 7. The operational amplifier 202 detects the potential of the second electrode 4 with reference to the comparison electrode 7. The operational amplifier 203 detects a difference between the output potential of the operational amplifier 201 and the output potential of the operational amplifier 202.

  One end of the conductor portion 516a is connected to the gate electrode of the transistor 514a, and the other end is connected to the above-described conductor portion 516d. The conductor portion 516d is electrically connected to the first electrode 3 through the conductor portion 61. Thus, the gate electrode of the transistor 514a and the first electrode 3 are electrically connected. Therefore, the drain current of the transistor 514a changes in accordance with the change in the potential of the first electrode 3.

Similarly, the conductor portion 516b has one end connected to the gate electrode of the transistor 514b and the other end connected to the above-described conductor portion 516e. The conductor portion 516e is electrically connected to the second electrode 4 through the conductor portion 62. Thus, the gate electrode of the transistor 514b and the second electrode 4 are electrically connected. Therefore, the drain current of the transistor 514b changes in accordance with the change in the potential of the second electrode 4.
The conductor portion 516c has one end connected to the gate electrode of the transistor 514c and the other end connected to the above-described conductor portion 516f.

The functional element 51 is activated by energization from the power source 52. The power source 52 is not particularly limited as long as it can supply power capable of operating the functional element 51. For example, the power source 52 may be a battery such as a button-type battery or has a power generation function such as a piezoelectric element. It may be a power source using an element.
The functional element 51 is configured to be able to acquire temperature information detected by the temperature sensor 53. Thereby, the information regarding the temperature of a measurement object site | part can also be obtained. By using such temperature-related information, it is possible to measure the state of the measurement target part more accurately or predict the change of the measurement target part with high accuracy.
The temperature sensor 53 has a function of detecting the temperature of the measurement target portion of the concrete structure 100 that is the measurement target. Such temperature sensor 53 is not particularly limited, and various types of known temperature sensors such as a thermistor and a thermocouple can be used, for example.

  The functional element 51 also has a function of driving and controlling the communication circuit 54. For example, the functional element 51 includes information on the potential difference between the first electrode 3 and the second electrode 4 (hereinafter also simply referred to as “potential difference information”), and the pH or chloride ion concentration of the measurement target site is below a set value. Information (hereinafter also simply referred to as “pH information”) is input to the communication circuit 54. The functional element 51 also inputs information related to the temperature detected by the temperature sensor 53 (hereinafter also simply referred to as “temperature information”) to the communication circuit 54.

The communication circuit 54 has a function of supplying power to the antenna 55 (transmission function). Thereby, the communication circuit 54 can wirelessly transmit the input information via the antenna 55. The transmitted information is received by a receiver (reader) provided outside the concrete structure 100.
The communication circuit 54 includes, for example, a transmission circuit for transmitting electromagnetic waves, a modulation circuit having a function of modulating a signal, and the like. Note that the communication circuit 54 receives a down-converter circuit having a function of converting a signal frequency to a low level, an up-converter circuit having a function of converting a signal frequency to a large level, an amplifier circuit having a function of amplifying a signal, and electromagnetic waves. And a demodulator circuit having a function of demodulating a signal.

The antenna 55 is not particularly limited, but is made of, for example, a metal material, carbon or the like, and has a form such as a winding or a thin film.
Further, the functional element 51 is configured to be able to acquire a clock signal from the oscillator 56. Thereby, each circuit can be synchronized and time information can be added to various information.
The oscillator 56 is not particularly limited. For example, the oscillator 56 includes an oscillation circuit using a crystal resonator.
In the measuring method using the sensor device 1 configured as described above, the first electrode 3 and the second electrode 4 are respectively embedded in the concrete structure 100 that is a measurement object, and the first electrode 3 is embedded. The state of the concrete structure 100 is measured based on the potential difference between the first electrode 4 and the second electrode 4.

Hereinafter, the operation of the sensor device 1 will be described by taking as an example the case where the first electrode 3 is made of Pt and the second electrode 4 is made of Ni.
In the concrete structure 100 immediately after placing, the concrete 101 exhibits strong alkalinity if it is properly placed. Therefore, at this time, the second electrode 4 forms a stable passive film. As a result, the potential difference between the first electrode 3 and the second electrode 4 immediately after placing the concrete is reduced.

Thereafter, in the concrete structure 100, the pH of the concrete 101 gradually changes to the acidic side due to the influence of carbon dioxide, acid rain, exhaust gas, and the like.
When the pH of the concrete 101 is lowered to about 10, the passive film of the second electrode 4 starts to collapse, and the natural potential is lowered (decreased). Thereby, the potential difference between the first electrode 3 and the second electrode 4 is increased.

By using such a detection result, it is possible to monitor a change with time in quality after placing the concrete structure 100. Therefore, deterioration (neutralization and salt intrusion) of the concrete 101 can be grasped before the reinforcing bars 102 are corroded. Thereby, before the reinforcing bar 102 corrodes, the concrete structure 100 can be repaired by painting, preservative-mixed mortar, or the like.
It can also be determined whether or not there was an abnormality when placing the concrete structure 100. Therefore, the initial trouble of the concrete structure 100 can be prevented and the quality of the concrete structure 100 can be improved.

  As described above, according to the sensor device 1 of the first embodiment, since the first electrode 3 and the second electrode 4 are each covered with the insulating film 8, the continuous pores (pores) of the insulating film 8. ), The moisture can be condensed on the first electrode 3 and the second electrode 4 at a lower relative humidity. Therefore, liquid water can be stably present on the first electrode 3 and the second electrode 4.

  For this reason, even if the relative humidity in the concrete 101 changes with changes in the humidity and temperature of the external environment, fluctuations in the amount of water on the first electrode 3 and the second electrode 4 are prevented. be able to. As a result, it is possible to prevent the natural potential of the first electrode 3 and the second electrode 4 from fluctuating due to changes in humidity and temperature of the external environment, and to measure the state of the measurement target portion of the concrete 101 with high accuracy. it can.

Second Embodiment
Next, a second embodiment of the present invention will be described.
FIG. 9 is a diagram illustrating an example of a usage state of the sensor device according to the second embodiment of the present invention.
Hereinafter, the second embodiment will be described with a focus on differences from the above-described embodiment, and description of similar matters will be omitted.

The sensor device of the second embodiment is substantially the same as the sensor device of the first embodiment, except that the shape and number of the first electrode and the second electrode are different in plan view and the number of the first electrode and the structure of the first electrode. is there. In addition, the same code | symbol is attached | subjected to the structure similar to embodiment mentioned above.
The sensor device 1A of the present embodiment includes a main body 2A, and a plurality of first electrodes 3a, 3b, 3c and a plurality of second electrodes 4a, 4b, 4c provided on the main body 2A.
Although not shown, the sensor device 1A is provided so as to cover the first electrodes 3a, 3b, 3c and the plurality of second electrodes 4a, 4b, 4c, and the insulating film 8 of the first embodiment described above. It has an insulating film similarly configured. Thereby, the fluctuation | variation of the moisture content on the 1st electrode 3a, 3b, 3c and several 2nd electrode 4a, 4b, 4c can be prevented.

In the present embodiment, the first electrodes 3a, 3b, 3c and the second electrodes 4a, 4b, 4c are provided apart from each other. The first electrodes 3 a, 3 b, 3 c and the second electrodes 4 a, 4 b, 4 c are installed such that the electrode surfaces are perpendicular or substantially perpendicular to the outer surface of the concrete structure 100. .
The plurality of first electrodes 3 a, 3 b, 3 c are different from each other in distance from the outer surface of the concrete structure 100. Specifically, a plurality of first electrodes 3a, 3b, 3c are provided in this order from the outer surface side of the concrete structure 100 to the inside.
Similarly, the plurality of second electrodes 4 a, 4 b, 4 c have different distances from the outer surface of the concrete structure 100. Specifically, a plurality of second electrodes 4a, 4b, and 4c are provided in this order from the outer surface side of the concrete structure 100 to the inside.

Furthermore, the first electrode 3a and the second electrode 4a are installed such that the distances from the outer surface of the concrete structure 100 are equal to each other. The first electrode 3b and the second electrode 4b are installed so that the distances from the outer surface of the concrete structure 100 are equal to each other. The 1st electrode 3c and the 2nd electrode 4c are installed so that the distance from the outer surface of the concrete structure 100 may become mutually equal.
In such 1st electrode 3a, 3b, 3c and 2nd electrode 4a, 4b, 4c, 1st electrode 3a and 2nd electrode 4a make a pair, and 1st electrode 3b and 2nd electrode The electrode 4b makes a pair, and the first electrode 3c and the second electrode 4c make a pair.
In the present embodiment, the sensor device 1A includes a potential difference between the first electrode 3a and the second electrode 4a, a potential difference between the first electrode 3b and the second electrode 4b, and the first electrode 3c and the second electrode 4b. The potential difference from the other electrode 4c can be measured by a functional element (not shown).

  According to such a sensor device 1A according to the second embodiment, the installation environment of the first electrode 3a and the second electrode 4a, the installation environment of the first electrode 3b and the second electrode 4b, and the first It is possible to accurately detect whether or not the pH of the installation environment of the first electrode 3c and the second electrode 4c is less than or equal to the set value. Each potential difference is measured, so that it is possible to accurately detect whether the pH of the installation environment of the first electrodes 3a, 3b, 3c and the second electrodes 4a, 4b, 4c is equal to or lower than a set value. That is, it is possible to accurately detect whether the pH at a position where the depth from the outer surface of the concrete structure 100 is different is a set value or less. Thereby, it is possible to know the speed at which the pH of the concrete 101 changes to the acidic side. Therefore, the penetration | invasion prediction to the depth direction of neutralization (or salt damage) of the concrete structure 100 can be performed effectively.

<Third Embodiment>
Next, a third embodiment of the present invention will be described.
FIG. 10 is a plan view for explaining the first electrode, the second electrode, and the functional element of the sensor device according to the third embodiment of the present invention. FIG. 11 is a plan view of the first electrode, the second electrode, and the functional element shown in FIG. It is sectional drawing for demonstrating the electrode of 2 (AA sectional view taken on the line in FIG. 3).

Hereinafter, the third embodiment will be described with a focus on differences from the above-described embodiment, and description of similar matters will be omitted.
The sensor device of the third embodiment is substantially the same as the sensor device of the first embodiment, except that the configuration of the insulating film, the first electrode, and the second electrode is different. In addition, the same code | symbol is attached | subjected to the structure similar to embodiment mentioned above.

The sensor device 1B of the present embodiment is provided so as to cover the main body 2B, the first electrode 3B and the second electrode 4B provided on the main body 2B, and the first electrode 3B and the second electrode 4B. And the insulating film 8B.
The first electrode 3B is configured in the same manner as the first electrode 3 of the first embodiment described above except that the recess 31 is omitted. Similarly, the second electrode 4B is configured in the same manner as the second electrode 4 of the first embodiment described above except that the recess 41 is omitted.
The first electrode 3B and the second electrode 4B are covered with an insulating film 8B.

The insulating film 8B is configured in the same manner as the insulating film 8 of the first embodiment described above except that a through hole 81B penetrating in the thickness direction is formed.
The through hole 81B formed in the insulating film 8B is patterned by etching.
In the present embodiment, since the insulating film 8B is composed of a porous body having continuous pores, the through-hole 81B itself may cause a capillary condensation effect or does not cause a capillary condensation effect. It may be a thing.

  When the through-hole 81B itself produces a capillary condensation effect, the continuous pores of the porous body constituting the insulating film 8B and the through-hole 81B can effectively produce a capillary aggregation effect. Further, even when the through hole 81B itself does not cause the capillary aggregation effect, the presence of the through hole 81B causes the first electrode 3B and the second electrode through the continuous pores of the porous body constituting the insulating film 8B. It is possible to promote the supply of moisture to 4B.

  Further, such a through-hole 81B is formed by contacting the aggregate in the concrete 101 with the insulating film 8B on the first electrode 3B or the second electrode 4B, like the concave portion 81 of the first embodiment described above. In addition, a gap can be generated between the insulating film 8B and the aggregate. Therefore, components (water, Ca ions, etc.) in the concrete 101 are supplied to the first electrode 3B or the second electrode 4B through the gap, and the amount of water on the first electrode 3B and the second electrode 4B. Can be stabilized.

In the present embodiment, the through-hole 81B includes a plurality of first portions (slits) 811 extending in parallel with each other in a plan view and a plurality of second portions orthogonal to the first portion 811 in a plan view and extending in parallel with each other. (Slit) 812. That is, the through hole 81B has a lattice shape in plan view.
The widths (slit widths) of the first portion 811 and the second portion 812 are not particularly limited. For example, the through hole 81B itself does not cause the capillary condensation effect as described above. In this case, it is preferably 50 nm or more and 100 nm or less (submicron), and when the through-hole 81B itself causes a capillary condensation effect as described above, it is preferably 2 nm or more and 50 nm or less.
Moreover, although the space | interval of the 1st parts 811 and the 2nd parts 812 is not specifically limited, respectively, they are 5 nm or more and about 200 nm or less.
The sensor device 1B of the third embodiment as described above also prevents the natural potentials of the first electrode 3B and the second electrode 4B from fluctuating due to changes in the humidity and temperature of the external environment, and the measurement target region. Can be measured with high accuracy.

<Fourth embodiment>
Next, a fourth embodiment of the present invention will be described.
FIG. 12 is a cross-sectional view for explaining the first electrode and the second electrode of the sensor device according to the fourth embodiment of the present invention.
Hereinafter, the fourth embodiment will be described with a focus on differences from the above-described embodiment, and description of similar matters will be omitted.
The sensor device of the fourth embodiment is substantially the same as the sensor device of the first embodiment except that the configuration of the insulating film, the comparison electrode, and the second electrode is different. In addition, the same code | symbol is attached | subjected to the structure similar to embodiment mentioned above.

The sensor device 1C according to the present embodiment includes a main body 2C, a first electrode 3C, a second electrode 4C, a comparison electrode 7C provided on the main body 2C, a first electrode 3C, and a second electrode 4C. And an insulating film 8C provided so as to cover the comparison electrode 7C.
The first electrode 3C is configured in the same manner as the first electrode 3 of the first embodiment described above.
On the other hand, the second electrode 4 </ b> C is the same as the second electrode 4 of the first embodiment described above except that the second electrode 4 </ b> C is configured by a base 42 and a conductor film 43 provided so as to cover the base 42. It is configured.

  The base 42 and the conductor film 43 are made of different materials. Also, the conductor film 43 is preferable because it is made of a metal material that is different from the constituent material of the first electrode 3C and can form a passive film. Thereby, the pH change of a measurement object site | part can be measured in two steps. In this case, for example, the base 42 is made of Pt, the conductor film 43 is made of Fe, and the first electrode 3C is made of Ni.

The comparison electrode 7C is connected to a functional element (not shown) in the same manner as the comparison electrode 7 of the first embodiment described above.
The comparison electrode 7C is made of a noble metal such as Pt or Au.
In addition, a recess is formed on the surface of the comparative electrode 7C, as in the case of the first electrode 3C and the second electrode 4C.

The comparison electrode 7C, the first electrode 3C, and the second electrode 4C are covered with an insulating film 8C.
The insulating film 8C is configured in the same manner as the insulating film 8 of the first embodiment described above except that a through hole 82C penetrating in the thickness direction is formed and the insulating film 8C is formed of a dense body.
The through hole 82C formed in the insulating film 8C is patterned by etching. Thereby, the insulating film 8C having the through hole 82C that can cause the capillary aggregation effect can be formed relatively easily. In the present embodiment, the through-hole 82B itself produces a capillary aggregation effect. Thereby, even if the insulating film 8C is composed of a dense body, a capillary condensation effect can be produced.

The through holes 82C have a lattice shape in plan view, like the through holes 81B of the third embodiment described above.
The widths of the slits constituting such a through hole 82C are not particularly limited, but are preferably 2 nm or more and 50 nm or less.
The sensor device 1C of the fourth embodiment as described above also prevents the natural potentials of the first electrode 3C and the second electrode 4C from fluctuating due to changes in the humidity and temperature of the external environment, and the measurement target region. Can be measured with high accuracy.

As mentioned above, although the sensor apparatus of this invention was demonstrated based on embodiment of illustration, this invention is not limited to this.
For example, in the sensor device of the present invention, the configuration of each part can be replaced with any configuration that exhibits the same function, and any configuration can be added.
In the above-described embodiment, the case where the first electrode and the second electrode are provided on the substrate has been described as an example. However, the present invention is not limited to this. For example, the first electrode and the second electrode are For example, you may provide on the outer surface of the part comprised with the sealing resin of the main body of a sensor apparatus.

  In the above-described embodiment, the case where the first electrode and the second electrode are each in the form of a thin film has been described as an example. However, the present invention is not limited to this, and the shapes of the first electrode and the second electrode are respectively For example, it may have a block shape, a line shape, or the like. In the above-described embodiment, the first electrode and the second electrode are provided along the outer surface of the main body of the sensor device, respectively. However, the first electrode and the second electrode are respectively provided on the outer side of the main body of the sensor device. You may make it protrude from the surface. Further, the installation positions and sizes (magnitude relations) of the first electrode and the second electrode are not limited to the above-described embodiment and may be arbitrary as long as the above-described measurement is possible.

In the above-described embodiment, the case where the functional element includes a CPU, an A / D conversion circuit, and a differential amplifier circuit has been described as an example. However, the functional element is not limited thereto. Other circuits such as a drive circuit may be incorporated.
In the above-described embodiment, the case where the information about the potential difference between the first electrode and the second electrode is transmitted to the outside of the sensor device by wireless transmission using active tag communication has been described as an example. Information may be transmitted to the outside of the sensor device using passive tag communication, or information may be transmitted to the outside of the sensor device by wire.

In the above-described embodiment, the functional element 51, the power source 52, the temperature sensor 53, the communication circuit 54, the antenna 55 and the oscillator 56 are accommodated in the main body 2, and these are combined with the first electrode 3 and the second electrode 4. The case where the measurement object is embedded in the concrete structure 100 has been described as an example. However, the functional element 51, the power source 52, the temperature sensor 53, the communication circuit 54, the antenna 55, and the oscillator 56 are provided outside the measurement object. May be.
In the above-described embodiment, the case where the insulating film having the through hole covers both the first electrode and the second electrode has been described as an example. However, the insulating film having the through hole has the first electrode and the second electrode. The effect of the present invention can be obtained if at least one of the electrodes is covered.

1, 1A, 1B, 1C ... Sensor device 2, 2A, 2B, 2C ... Main body 3, 3B, 3C ... First electrode 3a, 3b, 3c ... First electrode 4, 4B, 4C ... Second electrode 4a, 4b, 4c ... Second electrode 7, 7C ... Comparative electrode 8, 8B, 8C ... Insulating film 21 ... Substrate 23 ... Insulating layer 24 ... Sealing part 25 ... Protective film 31 ... Recess 41 ... Recess 42 ... Base 43 ... Conductor film 51 ... Functional element 52 ... Power supply 53 ... Temperature sensor 54 ... Communication circuit 55 ... Antenna 56 ... Oscillator 61 ... Conductor part 62 ... Conductor part 81 ... Recessed part 81B, 82C ... Through hole 82 ... Hole 83 ... Porous body 100 ... Concrete structure 101 ... Concrete 102 ... Reinforcing bars 201, 202, 203 ... Operational amplifier 241 Opening 511 CPU 512 Conversion circuit 513 Substrate 514 Differential amplification circuit 514a Transistor 514b Transistor 514c Transistor 514d Current mirror circuit 515a, 515b Interlayer insulation film 516a ... Conductor part 516b ... Conductor part 516c ... Conductor part 516d ... Conductor part 516e ... Conductor part 516f ... Conductor part 811 ... First part 812 ... Second part

Claims (11)

A first electrode;
A second electrode spaced apart from the first electrode;
An insulating film provided so as to cover at least one of the first electrode and the second electrode, and having a through hole or a through groove penetrating in the thickness direction;
A functional element having a function of measuring a potential difference between the first electrode and the second electrode;
A sensor device configured to be able to measure a state of a measurement target part based on a potential difference measured by the functional element.   The sensor device according to claim 1, wherein the insulating film is formed of a porous body having a continuous hole in which adjacent holes communicate with each other, and the continuous hole forms at least a part of the through hole.   The sensor device according to claim 2, wherein a concave portion is formed on a surface of the insulating film opposite to the first electrode and the second electrode. Recesses are formed on the surfaces of the first electrode and the second electrode,
The sensor device according to claim 3, wherein the insulating film has a recess formed following the recess.   The sensor device according to claim 1, wherein the through hole or the through groove is patterned by etching.   The sensor device according to claim 1, wherein the insulating film is provided so as to cover both the first electrode and the second electrode.   The sensor device according to claim 1, wherein the insulating film has alkali resistance.   At least one of the first electrode and the second electrode forms a first passive film on the surface or is present on the surface in accordance with an environmental change of the measurement target site. The sensor device according to any one of claims 1 to 7, wherein the sensor device is made of a metal material that eliminates the first passive film.   The sensor device according to claim 8, wherein the metal material is iron or an iron-based alloy.   The functional element also has a function of detecting whether a pH or a chloride ion concentration of the measurement target site is equal to or lower than a set value based on a potential difference between the first electrode and the second electrode. The sensor device according to any one of 1 to 9. An antenna and a communication circuit having a function of supplying power to the antenna;
The sensor device according to claim 1, wherein the functional element also has a function of driving and controlling the communication circuit.

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