TW201939031A - Humidity detection device - Google Patents

Abstract

A humidity detection device according to one aspect of the present invention is able to perform stable measurement by suppressing drift of a measurement value in humidity detection. The humidity detection device is provided with: an insulation layer provided on a main surface of a base material; a reference part provided on the insulation layer; a detection part provided on the insulation layer so as to be juxtaposed with the reference part; and common wiring provided between the reference part and the detection part. The reference part has: a reference first electrode provided on the main surface of the base material; a reference dielectric part provided so as to encircle the reference first electrode; and a reference second electrode provided so as to encircle the reference dielectric part. The detection part has: a detection first electrode provided on the main surface of the base material; a detection dielectric part provided so as to encircle the detection first electrode; and a detection second electrode which is provided so as to encircle the detection dielectric part and in which a through hole is provided. The common wiring is provided so as to be electrically conductive to the reference first electrode and the detection first electrode by passing through the insulation layer.

Description

Humidity detection device

The present invention relates to a humidity detection device, and more specifically, to a humidity detection device that detects humidity using a detection portion with a reference portion as a reference.

As a humidity detection device, a configuration is known in which a dielectric portion is provided between two electrodes, and the humidity is detected based on changes in the electrical characteristics (capacitance, resistance) of the dielectric portion. For example, a device (capacitive humidity detection device) that detects humidity based on changes in electrostatic capacitance includes a reference capacitor section (reference section) that is not affected by the humidity of the outside air, and a humidity that changes the capacitance according to the humidity of the outside air. Detection capacitor section (detection section).

The reference part has a structure in which moisture does not invade from outside air, and constitutes a fixed capacitor regardless of humidity. On the other hand, the detection unit has a structure in which moisture can invade from outside air, and a structure in which the capacitance changes according to humidity. In such a capacitive humidity detection device, the relative humidity is calculated based on the difference between the output voltage from the detection section and the output voltage from the reference section.

Patent Document 1 discloses a moisture-sensitive element that seeks to improve the connectivity between the upper electrode and the connection terminal of the upper electrode and to improve the quality and reliability. The moisture-sensitive element is provided with a connection terminal of an upper electrode on a substrate, and a layer of metal film is formed from the upper electrode connection terminal to cover the step of the moisture-sensitive film to the moisture-sensitive film.

Patent Document 2 discloses an improvement in electrical connectivity between the upper electrode and the electrode terminal for the upper electrode, and between the upper electrode electrode terminal, the lower electrode electrode terminal, and the lead wire, thereby improving quality and reliability. Humidity detection element. In this humidity detection element, an electrode pad for an upper electrode is formed by laminating an extended portion including one end portion of an upper electrode on a pad for an electrode.

In Patent Documents 3 and 4, a humidity sensor is disclosed in which a lower electrode of a reference portion (reference portion) and a lower electrode of a detection portion (sensor portion) are conducted on a substrate.
[Prior technical literature]
[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 06-123725
[Patent Document 2] Japanese Patent Laid-Open No. 06-094663
[Patent Document 3] International Publication No. 2011/065507
[Patent Document 4] International Publication No. 2011/113711

[Problems to be solved by the invention]

In a humidity detection device having a reference part and a detection part, when a common wild wire that conducts the lower electrode of the reference part and the lower electrode of the detection part is provided on the substrate, in order to prevent the upper electrode from contacting the common wild wire, A recess (opening) is provided in the upper electrode. When a recessed portion is provided on the upper electrode, a leakage electric field is generated between the end of the recessed portion and the lower electrode, which becomes a cause of drift in the measured value.

An object of the present invention is to provide a humidity detection device capable of suppressing a drift of a measurement value of the humidity detection and performing a stable measurement.
[Technical means to solve the problem]

In order to solve the above-mentioned problem, one aspect of the present invention is a humidity detecting device including: an insulating layer provided on a main surface of a base material; a detecting portion provided on the insulating layer; and a reference portion provided on Above the insulating layer and juxtaposed with the detection section; and a common wild wire, which is disposed between the detection section and the reference section.
The detection unit includes: a first electrode for detection, which is provided on the insulating layer; a dielectric portion for detection, which is provided so as to surround the first electrode for detection; and a second electrode for detection, which surrounds the detection medium. The electric part is provided as a through hole.
The reference section includes: a first reference electrode, which is provided on the insulating layer; a reference dielectric section, which is provided so as to surround the first electrode for reference; and a second electrode, which is used to surround the reference electrode. The way of the electric quality department is set.
The common wild wire is provided so as to be electrically connected to the first electrode for detection and the first electrode for reference through the insulating layer.

According to this configuration, since the common wild line passes through the insulating layer, the common wild line can be provided without providing a recess (opening) for the second electrode for detection and the second electrode for reference. Thereby, the second electrode for detection can surround the entire dielectric portion for detection, and the second electrode for reference can surround the entire dielectric portion for reference, thereby suppressing unnecessary generation at the ends of the second electrodes. Leakage electric field.

In the above-mentioned humidity detection device, it is preferable that no through hole is provided in the second electrode for reference. Thereby, an unnecessary leakage electric field between the reference first electrode and the reference second electrode caused by the through hole is not generated.

The above-mentioned humidity detection device further includes: a reference lead wire which is in communication with the second electrode for reference; and a detection lead wire which is in communication with the second electrode for detection; the detection lead wire and the reference lead wire may be used. Set in the insulation layer.

In the above-mentioned humidity detection device, it is preferable that the reference lead-out wiring and the detection lead-out wiring are provided on the same layer as the common wild wire. Thereby, it is possible to form a detection lead-out wiring, a reference lead-out wiring, and a common wild wire in the same step.

In the above-mentioned humidity detection device, a protective layer having a higher moisture resistance than the insulating layer may be provided around the detection portion and the reference portion on the insulating layer. This can prevent moisture from entering the dielectric portion from the side surface of the second electrode for reference and the side surface of the second electrode for detection.

In the above-mentioned humidity detection device, it is preferable that a protective layer is not provided on the second electrode for detection. Thereby, the influence of the leakage electric field in the vicinity of the through hole of the second electrode for detection does not reach the protective layer, and the accuracy of the measured value is improved.
[Effect of the invention]

According to the present invention, it is possible to provide a humidity detection device capable of suppressing the drift of the measurement value of the humidity detection and performing stable measurement.

Hereinafter, embodiments of the present invention will be described based on the drawings. Furthermore, in the following description, the same reference numerals are given to the same components, and descriptions of components that have been described once are appropriately omitted.

(Construction of Humidity Detection Device)
1 (a) and 1 (b) are diagrams illustrating a humidity detection device according to this embodiment.
A cross-sectional view of the humidity detection device 1 is shown in FIG. 1 (a), a plan view of the humidity detection device 1 is shown in FIG. 1 (b), and a cross-sectional view shown in FIG.

As shown in FIG. 1, the humidity detection device 1 of this embodiment is a device that detects the humidity of the outside air as an electrical signal, and includes an insulating layer 30, a detection portion 10, a reference portion 20, and A total of 70 wildcard lines. The humidity detection device 1 detects humidity based on a capacitance difference between the detection section 10 and the reference section 20.

As the substrate 50, for example, silicon is used. An insulating layer 30 made of, for example, silicon oxide is formed on the main surface 50 a of the substrate 50, and a detection portion 10 and a reference portion 20 are formed on the insulating layer 30 in parallel. Further, a pad electrode 15 is provided on the insulating layer 30 to be in electrical communication with the detection portion 10 and the reference portion 20.

The detection unit 10 includes a detection first electrode 110 provided on the insulating layer 30, a detection dielectric portion 130 provided to surround the detection first electrode 110, and a detection dielectric portion 130 to surround the detection dielectric portion 130. A second electrode 120 is provided for detection. Thereby, in the first direction D1 orthogonal to the main surface 50a, a capacitor in which a first electrode 110 for detection, a dielectric part 130 for detection, and a second electrode 120 for detection are sequentially laminated is formed.

As the first electrode 110 for detection and the second electrode 120 for detection, as a conductive material that is not easily oxidized, for example, a high-melting metal material such as ruthenium (Ru) and tantalum (Ta) is used. In addition, as the detection dielectric portion 130, for example, a polyfluorene-based resin is used.

A plurality of through-holes 120h are provided at the second electrodes 120 for detection at specific intervals. The external moisture reaches the detection dielectric portion 130 through the through-hole 120h. The dielectric constant of the detection dielectric portion 130 changes depending on the amount of water contained in the detection dielectric portion 130. Thereby, the change in the electrostatic capacitance between the detection first electrode 110 and the detection second electrode 120 can detect the humidity based on the changed capacitance.

The reference section 20 and the detection section 10 have the same laminated structure. That is, the reference portion 20 includes a first reference electrode 210 provided on the insulating layer 30, a reference dielectric portion 230 provided to surround the first reference electrode 210, and a reference dielectric portion to surround the first reference electrode 210. The second electrode 220 is provided in the 230 manner.

Thereby, in the first direction D1, a capacitor in which the reference first electrode 210, the reference dielectric portion 230, and the reference second electrode 220 are sequentially laminated is formed. Since the reference second electrode 220 is not provided with a through-hole, and the reference dielectric portion 230 is surrounded by the second reference electrode 220, moisture from the outside hardly enters the reference portion 20. Therefore, the dielectric constant of the reference dielectric portion 230 hardly changes. Therefore, the capacitance of the reference portion 20 composed of the first reference electrode 210, the second reference electrode 220, and the reference dielectric portion 230 is substantially fixed. The relative humidity can be detected based on the difference between the output voltage of the electrostatic capacitance based on the reference portion 20 and the output voltage of the electrostatic capacitance based on the detection portion 10.

A protective layer 40 may also be provided around the detection portion 10 and the reference portion 20 on the insulating layer 30. When the protective layer 40 is provided, a material having higher moisture resistance than the insulating layer 30 is preferably used. The protective layer 40 is made of, for example, silicon nitride (SiN). Thereby, it is possible to suppress the moisture self-detection from the side surface of the second electrode 120 and the side surface of the reference second electrode 220 from entering the detection dielectric portion 130 and the reference dielectric portion 230.

The common wild line 70 is provided between the detection section 10 and the reference section 20. In this embodiment, the common wild line 70 is provided so as to be electrically connected to the first electrode 110 for detection and the first electrode 210 for reference through the insulating layer 30. That is, the common wild line 70 is provided between the main surface 50 a of the base material 50 and the surface 30 a of the insulating layer 30 opposite to the main surface 50 a.

The common wild line 70 and the detection first electrode 110 and the reference first electrode 210 are located in different layers from each other. Therefore, the detection first electrode 110 and the reference first electrode 210 provided on the insulating layer 30 are in a state of being conducted by the common wild line 70 through a through hole provided at the end of the common wild line 70.

A detection lead-out wire 12 is provided between the detection second electrode 120 and the pad electrode 15, and a reference lead-out wire 13 is provided between the reference second electrode 220 and the pad electrode 15. The detection lead wires 12 and the reference lead wires 13 are provided in the insulating layer 30. The detection lead-out wiring 12 and the reference lead-out wiring 13 are preferably provided on the same layer as the common wild wire 70. Thereby, the detection lead-out wiring 12, the reference lead-out wiring 13, and the common wild line 70 can be formed in the same step.

As described above, in the humidity detection device 1 of this embodiment, since the common wild wire 70 is provided through the insulating layer 30, it is not necessary to provide a common portion under the recess (opening) provided in the second electrode 120 for detection and the second electrode 220 for reference. Wiring 70. Since it is not necessary to provide recesses (openings) for passing through the common wild line 70 in the second electrode 120 for detection and the second electrode 220 for reference, the outer periphery of the second electrode 120 for detection becomes a fuller dielectric than the entire periphery for the detection The mass portion 130 is more outward in the outer peripheral position. In addition, the outer peripheral position of the second electrode for reference 220 is located more outward than the outer peripheral position of the reference dielectric portion 230 throughout the entire periphery.

Thereby, the second electrode 120 for detection can surround the entire dielectric body for detection 130 except the through hole 120h, and the second electrode 220 for reference can surround the entire dielectric body 230 for reference. Therefore, an unnecessary leakage electric field can be prevented from being generated at the ends of each of the second electrode 120 for detection and the second electrode 220 for reference.

2 (a) and 2 (b) are diagrams illustrating a humidity detection device of a reference example.
A sectional view of the humidity detection device 1 is shown in FIG. 2 (a), and a top view of the humidity detection device 2 is shown in FIG. 1 (b). The cross-sectional view shown in FIG. 2 (a) is a cross-sectional view taken along the line BB shown in FIG. 2 (b).

In the humidity detection device 2 of the reference example, the common wild wire 75 is provided on the same layer as the detection first electrode 110 and the reference first electrode 210. That is, the common wild line 75 is provided on the insulating layer 30 so as to connect the first electrode 110 for detection and the first electrode 210 for reference.

In the case of such a wiring structure, in order to prevent the common wild wire 75 from being short-circuited with the second electrode 120 for detection and the second electrode 220 for reference, the ends of the second electrode 120 for detection and the second electrode 220 for reference A recessed portion 90 is provided. The recessed portion 90 is provided at a position overlapping the common wild line 75 in the first direction D1. By providing the common wild line 75 in alignment with the position of the concave portion 90, the distance between the common wild line 75 and the second electrode 120 for detection and the second electrode 220 for reference can be ensured to prevent a short circuit between the two.

Further, in the humidity detection device 2 of the reference example, the dielectric portion 130 for detecting the position of the recessed portion 90 and the dielectric portion 230 for reference are exposed, so the portion other than the through hole 120h is covered with the protective layer 40. In addition, since the protective layer 40 covers the edge of the through-hole 120h, the change in the dielectric constant of the portion is reflected in the reference portion 20, and therefore, the capacitance adjustment hole 220h may be provided in the reference second electrode 220.

In the humidity detection device 1 of this embodiment and the humidity detection device 2 of the reference example, a difference in electric field distribution occurs due to a difference in such a structure.
3 (a) to 4 (b) are diagrams illustrating simulation results of electric field distribution.
The simulation results of the electric field distribution in the central portion of the reference portion 20 are shown in Figs. 3 (a) and (b), and the simulation results of the electric field distribution in the end portion of the reference portion 20 are shown in Figs. 4 (a) and (b). (A) Simulation results of the humidity detection device 1 of this embodiment, and (b) Simulation results of the humidity detection device 2 of the reference example.

As shown in FIG. 3 (b), in the humidity detection device 2 of the reference example, a capacitance adjustment hole 220h is provided in a central portion of the second electrode 220 for reference. Therefore, the electric field in the central portion of the reference second electrode 220 of the humidity detection device 2 of the reference example is distributed at the end of the capacitance adjustment hole 220h, and a leakage electric field is generated. The influence of the electric field also reaches the protective layer 40 (refer to FIG. 3 (b)). ). On the other hand, as shown in FIG. 3 (a), in the humidity detection device 1 of the present embodiment, the center portion of the second electrode 220 for reference is not provided with a capacitance adjustment hole 220h and is flat. Therefore, the electric field distribution in the central portion of the reference second electrode 220 of the humidity detection device 1 of this embodiment is uniform.

As shown in FIG. 4 (b), in the humidity detection device 2 of the reference example, a recessed portion 90 is provided at the end of the reference second electrode 220 to prevent a short circuit with the common wild wire 70. Therefore, the electric field distribution at the end of the reference second electrode 220 of the humidity detection device 2 of the reference example generates a leakage electric field near the recessed portion 90, and the influence of the electric field also affects the protective layer 40. On the other hand, as shown in FIG. 4 (a), in the humidity detection device 1 of this embodiment, a recess is not provided at the end portion of the second reference electrode 220 to cover the reference dielectric portion 230. Set up to the end. Therefore, there is less leakage of the electric field at the end portion of the first reference electrode 210 or the end portion of the second reference electrode 220. In particular, in the humidity detection device 1 of this embodiment, since the protective layer 40 is not provided on the reference second electrode 220, there is no need to consider the influence of the electric field on the protective layer 40.

In FIGS. 3 and 4, simulation results of the electric field distribution in the reference portion 20 are shown, but the electric field distribution at the end of the second electrode 120 for detection is the same as that of the reference portion 20. The electric field distribution in the vicinity of the through hole 120h is the same as the electric field distribution in the vicinity of the capacitance adjustment hole 220h shown in FIG. 3 (b). However, in this embodiment, no protective layer is provided on the second electrode 120 for detection. 40, so there is no need to consider the effect of the electric field on the protective layer 40 near the through hole 120h.

FIG. 5 is a graph illustrating comparison results of drift characteristics.
The horizontal axis in FIG. 5 is time (hr), and the vertical axis is the capacitance change amount (% RH) since the initial measurement.
FIG. 5 shows drift characteristics G1 of the humidity detection device 1 of this embodiment and drift characteristics G2 of the humidity detection device 2 of the reference example. The drift characteristics G1 and G2 represent changes in measurement values of the humidity detection devices 1 and 2 from the start of measurement to the elapse of 1000 hours. According to the difference in the structure as described above, the drift amount of the humidity detection of the humidity detection device 1 of this embodiment is suppressed by about 1% compared to the drift amount of the humidity detection of the humidity detection device 2 of the reference example.

(Application example)
6 to 8 (b) are sectional views showing an application example of the humidity detection device.
In the application example shown in FIG. 6, a frame portion 60 is provided around the detection portion 10. The frame portion 60 is formed by, for example, etching silicon to form a frame type, and is connected to the base material 50 through an adhesive 65. By using silicon as the frame portion 60, the frame portion 60 can be constituted by the workability and hardness of silicon. Since the detection unit 10 is disposed in the opening 601 of the frame portion 60, external moisture is taken into the detection dielectric portion 130 from the opening 601 through the through hole 120 h of the second electrode 120 for detection. The dielectric constant of the detection dielectric portion 130 changes according to the moisture taken into the detection dielectric portion 130, and the humidity can be detected based on the dielectric constant.

The humidity detection device 1B shown in FIG. 7A has a structure in which an adhesive 65 for mounting the frame portion 60 is not provided on the reference portion 20. By not providing the adhesive 65 on the reference portion 20, the capacitance variation of the reference portion 20 can be suppressed. In other words, the electric field formed by applying a voltage to the first reference electrode 210 and the second reference electrode 220 is diffused to the reference dielectric portion 230 side and to the upper side of the second reference electrode 220. Since the adhesive 65 is not provided above the second reference electrode 220 for reference, it is not affected by the change in the dielectric constant of the adhesive 65 caused by the diffusion of the electric field, so that the capacitance change of the reference portion 20 can be suppressed.

In the humidity detection device 1C shown in FIG. 7 (b), an opening 601 of a frame portion 60 is provided above the detection portion 10 and the reference portion 20. That is, the frame portion 60 is not provided not only above the detection portion 10 but also above the reference portion 20. Thereby, the environment (structure) above the reference portion 20 is consistent with the environment (structure) above the detection portion 10, and the relative humidity can be calculated with high accuracy.

The humidity detection device 1D shown in FIG. 8 (a) has a structure in which, similar to the humidity detection device 1B, an adhesive 65 for mounting the frame portion 60 is not provided on the reference portion 20. The difference from the humidity detection device 1B is that the adhesive 65 is provided between the reference portion 20 and the detection portion 10. With this structure, similar to the humidity detection device 1B, it is not affected by the change in the dielectric constant of the adhesive 65 caused by the electric field diffusing above the reference portion 20. Furthermore, since the periphery of the reference portion 20 is surrounded by the adhesive 65, it is possible to prevent particles from adhering to the reference portion 20. This makes it possible to suppress a change in the capacitance of the reference portion 20 caused by the adhesion of the adhesive 65 or particles.

In the humidity detection device 1E shown in FIG. 8 (b), each of the detection section 10 and the reference section 20 has a structure separate from the adhesive 65 for mounting the frame section 60. For example, a pillar 603 is provided in the frame portion 60, and when the frame portion 60 is mounted, the detection portion 10 and the reference portion 20 are surrounded by the pillar 603. The adhesive 65 is adhered to the portion without the support 603 except the detection portion 10 and the reference portion 20. With this structure, the detection section 10, the reference section 20, and the adhesive 65 are not adjacent.

Since the adhesive 65 uses a resin such as polyimide, it has hygroscopicity. Due to the moisture absorption of the adhesive 65, the dielectric constant of the adhesive 65 changes. If the adhesive 65 is adjacent to the detection portion 10 and the reference portion 20, the detection portion 10 and the reference portion 20 are easily affected by changes in the dielectric constant of the adhesive 65. Like the humidity detection device 1E, since the detection section 10 and the reference section 20 are separated from the adhesive 65 by the pillar 603, they are not easily affected by the change in the dielectric constant of the adhesive 65, and can perform highly accurate humidity detection.

As described above, according to this embodiment, it is possible to provide the humidity detection devices 1, 1B, 1C, 1D, and 1E capable of suppressing the drift of the measurement value of the humidity detection and performing stable measurement.

Although the present embodiment has been described above, the present invention is not limited to these examples. For example, the detection method of the humidity of the detection section 10 and the reference section 20 is a method of detecting humidity for measuring capacitance as described above, or a method of detecting humidity by measuring resistance. In addition, an example in which ruthenium (Ru) or the like is used as an electrode material is exemplified, but other conductive materials such as ruthenium (Ru) or copper may be used. A protective material such as a silicone-based gel material may be provided so as to cover the detection portion 10 and the reference portion 20 as a countermeasure against the particles.

In addition, as for the above-mentioned embodiment, those skilled in the art who appropriately add, delete, or design changes to the constituent elements or those who appropriately combine the characteristics of the configuration examples of the embodiments, as long as they have the gist of the present invention, they are included in The scope of the invention.

1, 1B, 1C, 1D, 1E‧‧‧Humidity detection device

2‧‧‧Humidity detection device

10‧‧‧Testing Department

12‧‧‧test lead-out wiring

13‧‧‧Reference lead wiring

15‧‧‧pad electrode

20‧‧‧Reference Department

30‧‧‧ Insulation

30a‧‧‧face

40‧‧‧ protective layer

50‧‧‧ substrate

50a‧‧‧Main face

60‧‧‧Frame

65‧‧‧ Adhesive

70‧‧‧Total wild line

75‧‧‧Total wild line

90‧‧‧ recess

110‧‧‧1st electrode for detection

120‧‧‧ 2nd electrode for detection

120h‧‧‧through hole

130‧‧‧Dielectrics for testing

210‧‧‧ 1st electrode for reference

220‧‧‧ 2nd electrode for reference

220h‧‧‧Capacitor adjustment hole

230‧‧‧Reference Dielectrics Department

601‧‧‧ opening

603‧‧‧ Pillar

B-B‧‧‧line

D1‧‧‧1st direction

G1‧‧‧ drift characteristics

G2‧‧‧ drift characteristics

1 (a) and 1 (b) are diagrams illustrating a humidity detection device according to this embodiment.

2 (a) and 2 (b) are diagrams illustrating a humidity detection device of a reference example.

3 (a) and 3 (b) are diagrams illustrating simulation results of electric field distribution.

4 (a) and 4 (b) are diagrams illustrating simulation results of electric field distribution.

FIG. 5 is a graph illustrating comparison results of drift characteristics.

Fig. 6 is a sectional view showing an application example of the humidity detection device.

7 (a) and 7 (b) are sectional views showing an application example of the humidity detection device.

8 (a) and 8 (b) are sectional views showing an application example of the humidity detection device.

Claims (6)

A humidity detection device, comprising: An insulating layer disposed on the main surface of the substrate; A detection section provided on the above-mentioned insulating layer; A reference section, which is disposed on the insulating layer and is juxtaposed with the detection section; and A common wildcard line provided between the detection section and the reference section; and The detection unit has: A first electrode for detection, which is provided on the insulating layer; A detection dielectric portion provided to surround the first electrode for detection; and The second electrode for detection is provided so as to surround the above-mentioned dielectric portion for detection, and is provided with a through hole; and The above reference department has: A reference first electrode, which is disposed on the insulating layer; A reference dielectric portion provided so as to surround the first reference electrode; and The second reference electrode is provided so as to surround the reference dielectric portion; The above common wildcard line, The first electrode for detection and the first electrode for reference are electrically connected to each other through the insulating layer. The humidity detection device according to claim 1, wherein a through hole is not provided in the reference second electrode. If the humidity detection device of claim 1 or 2 is further provided, it further comprises: A detection lead wire which is electrically connected to the second electrode for detection; and The reference lead wire is electrically connected to the reference second electrode; and The detection lead wires and the reference lead wires are provided in the insulating layer. For example, the humidity detection device of claim 3, wherein the detection lead-out wiring and the reference lead-out wiring are arranged on the same layer as the common wild-wire. The humidity detecting device according to claim 1 or 2, wherein a protective layer having a higher moisture resistance than the insulating layer is provided around the detecting portion and the reference portion on the insulating layer. The humidity detection device according to claim 5, wherein the protective layer is not provided on the second electrode for detection.