JP2005233740A - Optical detection type hydrogen detection element and hydrogen detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical detection type hydrogen detection element and a hydrogen detection device for detecting hydrogen optically, having high sensitivity and excellent long-period reliability. <P>SOLUTION: This hydrogen detection element has a constitution formed so as to have the maximum length of 70 μm or less on a catalyst metal film pattern region provided on the same plane on a transparent substrate or on a metal oxide. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a photodetection type hydrogen detection element that safely detects the presence of hydrogen, and a hydrogen detection apparatus equipped with the same.

In general, gas sensors that detect flammable gases containing hydrogen, etc., are known to use semiconductor combustion, contact combustion, and light detection. However, in the case of the above flammable gases, hydrogen can be detected at room temperature. In addition, a highly safe photodetection type hydrogen sensor having an explosion-proof property and no ignition source such as an electrical contact is suitable.
This is because the sensor element is made of a material that changes its optical characteristics by incorporating hydrogen molecules and hydrogen atoms. When exposed to a hydrogen-containing atmosphere, the material will be discolored and expanded, and light Absorptivity, light transmittance, surface roughness, material volume, etc. change. At this time, when the sensor element is irradiated with light, the amount of reflected light and the amount of transmitted light change compared with those before exposure to a hydrogen atmosphere. By measuring this, the presence of hydrogen is detected.

As an example, there is a hydrogen detection element manufactured by forming a tungsten oxide hydroxide film on a flat tungsten substrate using an anodic oxidation method and then depositing a palladium film thinly as a catalyst film by vacuum deposition or sputtering (Patent Document) 1).
According to this method, when the atmosphere in which the detection element is placed is changed from normal air to air containing 1% hydrogen in a state where light having a wavelength of 1.4 μm is irradiated from the surface side toward the substrate. It is described that it responds to hydrogen in about 10 seconds, that is, the amount of reflected light changes.
The above method is composed of a laminated film of a metal oxide composed of a hydrous tungsten oxide film and a catalyst film composed of a palladium film. When palladium adsorbs hydrogen molecules, it dissociates into hydrogen atoms, and the dissociated hydrogen The atoms act on the hydrous tungsten oxide film located below the palladium film to cause discoloration, thereby causing changes in the light absorption and reflectance in the hydrous tungsten oxide film. This structure is known as one of highly sensitive hydrogen detection elements that can detect the presence of hydrogen to a low concentration range.

As another example, there is a photodetection type hydrogen detection element manufactured by forming, for example, only a Pd (palladium) thin film as a catalyst metal on a substrate (see Patent Document 2).
This is to detect the presence of hydrogen by measuring the change in the light transmittance or light reflectance of the Pd film itself caused by the hydrogen absorption of the Pd film. It is described that the device has a faster response time than the detection device using the metal oxide.

JP-A-7-72080

Japanese Patent Application Laid-Open No. 5-196569

The two types of photodetection-type hydrogen detection elements comprising the catalyst metal film / metal oxide bilayer structure and the catalyst metal film single layer described in the above prior art are widely known in terms of operating principle and structure. Many studies have been conducted on hydrogen detection performance.
However, since both of the above two types of hydrogen detecting elements use a catalytic metal film having the property of occluding and releasing hydrogen, the catalytic metal film itself is caused by repetitive stress caused by volume expansion and contraction generated at that time. However, it has the disadvantage of being very susceptible to damage. In the worst case, peeling of the catalytic metal film occurs, causing a significant decrease in detection performance, which is a problem in terms of long-term reliability.

  Accordingly, an object of the present invention is to provide a photodetection type hydrogen detection device that has dramatically improved the lifetime of the above two types of photodetection type hydrogen detection elements while maintaining the high sensitivity and stable detection performance so far. A detection element and a hydrogen sensor equipped with the detection element are provided.

The present inventors considered that the peeling of the catalyst metal film due to repeated stress is related to the size and length of the catalyst metal film deposited on the same plane.
Therefore, by researching the relationship between the deposition area of the palladium metal film, which is a catalytic metal film, and the shape deterioration of the film due to volume expansion / contraction during hydrogen storage / release, by reducing the deposition area of the palladium film, The present inventors have found that the influence of repeated stress on the film can be relaxed to a level that can be ignored and defects such as film peeling can be prevented.

A palladium film having a film thickness of 50 nm was formed on a flat glass substrate as a transparent substrate in seven deposition pattern sizes of 500 μmφ, 300 μmφ, 200 μmφ, 100 μmφ, 50 μmφ, 30 μmφ, and 10 μmφ, respectively.
And from normal air (1) left in air containing 3% hydrogen for 1 minute → (2) left in normal air for 5 minutes → (1) left in air containing 3% hydrogen for 1 minute → (2) The cycle of (1) → (2), which was allowed to stand in normal air for 5 minutes, was repeated 20 times in total, and the uneven state of the film surface before and after the hydrogen exposure experiment was measured.
As a result, it was found that with a pattern size of 50 μmφ or less, there was almost no change from the surface state before the experiment, that is, no film shape degradation such as film peeling due to repeated stress occurred.

Further, even when the same experiment was performed with the seven different rectangular patterns having the above-mentioned dimensions by changing the pattern shape from a circular shape to a quadrangular shape, the presence or absence of shape deterioration could be confirmed almost at the boundary of 50 μm ^□ . The maximum length at this time is about 70 μm of the diagonal length, and it was found from this result that the film shape does not deteriorate even if the maximum length of the pattern is 70 μm.
However, when the pattern size is larger than 100 μmφ and 100 μm ^□ , the film is lifted up or locally peeled off.
Even when the film thickness of the palladium film is increased to 80 nm, the surface unevenness is increased by about 10% compared to before the hydrogen exposure experiment at 50 μm ^□ (diagonal length = about 70 μm), but no significant film peeling is confirmed. It was. From this, it was found that if the longest dimension of the pattern is about 70 μm or less for both the circle and the rectangle, the film shape hardly deteriorates.

Further, a circular and rectangular pattern made of a tungsten oxide film having a thickness of 500 nm having the above seven dimensions is randomly deposited and formed on a flat glass substrate at intervals of a maximum of 30 μm, and then the film is formed using a vacuum deposition method. A 50 nm thick palladium film is deposited on the entire surface of the glass substrate so as to be deposited on the side of the tungsten oxide film, that is, a continuous film on the upper surface of the tungsten oxide film and the surface of the glass substrate. The hydrogen exposure experiment was conducted. At this time, the side surface of the tungsten oxide film pattern is processed and formed to be substantially perpendicular to the substrate surface.
As a result, in a larger pattern including a tungsten oxide film having a pattern shape including 100 μmφ and 100 μm ^□ , a lift of the palladium film was observed locally on the upper surface of the tungsten oxide film.
This defect has a greater degree of film peeling as the pattern size increases, and also in the peripheral part of the pattern where film peeling occurs, that is, in the palladium film on the glass substrate extending from the side surface of the tungsten oxide film and the side surface of the tungsten oxide film. Further, film peeling and surface roughness considered to be due to the influence of the film peeling were observed.
On the other hand, in the pattern having pattern dimensions of 50 μmφ and 50 μm ^□ (diagonal length = about 70 μm) or less, the above film peeling and surface roughness were not observed.

From the above, it has been found that the deterioration of the shape of the film can be prevented by reducing the deposition area of the catalytic metal film such as palladium, which has been damaged by the influence of repeated stress due to the insertion and extraction of hydrogen. Even when the catalytic metal film has a large area, it is equivalent to when the catalytic metal film on the same plane is patterned by reducing the maximum length on the same plane by providing locally steep steps. It has also been found that the film is resistant, that is, the film stress generated by the expansion and contraction of the catalytic metal film can be relaxed to prevent deterioration of the film shape.
That is, the present invention is characterized in that, in a hydrogen detection element formed by forming a catalytic metal film on a transparent substrate or a metal oxide, the maximum length in the catalytic metal film forming region on the same plane is 70 μm or less. By using an element having this structure, which is a photodetection type hydrogen detection element, the conventional high sensitivity and stable detection performance for hydrogen detection can be maintained, and at the same time, the lifetime of the element can be increased.

In the present invention, a catalyst film single film or a catalyst film / metal oxide bilayer structure film may be formed not only on the surface side of the transparent substrate but also on the back surface side. Since it becomes 2 times, further high sensitivity can be achieved.
In the above experiment, a pattern shape consisting of a circle and a rectangle is used. If the maximum length in the catalytic metal film pattern region on the same plane is 70 μm or less, any shape such as an ellipse or a polygon can be used. Obviously, a pattern may be used.

  Furthermore, the pattern may be other than a predetermined pattern, and if it is a catalyst film / metal oxide bilayer structure, a metal composed of amorphous crystal grains having a size or shape of about 0.1 to 10 μm. It is apparent that the object of the present invention can be achieved even when the oxide film is sparsely formed on the entire surface of the transparent substrate and then the catalyst film is deposited on the entire upper surface.

  In the above experiment, tungsten oxide is used for the metal oxide and palladium is used for the catalyst metal. However, the above hydrogen exposure experiment is performed using each combination of vanadium oxide and molybdenum oxide for the metal oxide and platinum for the catalyst metal. Even when the measurement was performed, the shape of the catalytic metal film did not deteriorate in any combination as long as it was within the dimensional range of the catalytic metal film pattern.

  The photodetection type hydrogen detection element of the present invention is a long-life element in which defects such as catalyst film peeling do not occur even when hydrogen exposure is repeated many times. In the case of a catalyst film / metal oxide structure, the shape of the metal oxide In some cases, the hydrogen sensitive surface increases, so that a photodetection type hydrogen detection element having a higher sensitivity and longer-term reliability than a conventional structure and a hydrogen detection device equipped with the same can be easily produced with good reproducibility.

  Hereinafter, the present invention will be described based on examples.

<Example 1>
FIG. 1 shows an embodiment of a hydrogen detecting element having a catalyst film / metal oxide bilayer structure according to the present invention.
A 500 nm-thickness tungsten oxide film 11 is deposited on the glass substrate 10 by using a well-known high-frequency magnetron sputtering method.
Using a photolithographic technique, a plurality of openings made of a resist pattern of 20 μmφ are provided over the entire surface of the substrate 10 at intervals of a maximum of 20 μm, a palladium film having a thickness of 50 nm is deposited using a well-known vacuum deposition method, and then lift-off method Thus, the unnecessary resist pattern and palladium film are removed to form a 20 μmφ palladium pattern 12, thereby completing the hydrogen detection element 13.
As a result of measuring and observing the surface of the catalyst membrane palladium pattern 12 after repeating the above-described hydrogen exposure experiment (hydrogen concentration of hydrogen-containing air is 1%) 100 times for the completed hydrogen detection element 13, the surface roughness was found. No shape degradation such as film peeling was observed.

At the same time, the light with a wavelength of 1.2 μm was irradiated from the surface side toward the substrate to observe the change in the amount of transmitted light, but it was confirmed that the transmitted light attenuated immediately after exposure to hydrogen-containing air. After 10 seconds, it attenuated to half the amount of transmitted light before exposure. Furthermore, it was confirmed that the same characteristics as the first time were obtained in the 100th hydrogen exposure with respect to the attenuation of transmitted light.
In the above embodiment, an example was described in which an element was fabricated using tungsten oxide and palladium. In addition to this, hydrogen exposure was performed in various combinations using vanadium oxide or molybdenum oxide as a metal oxide and platinum as a catalyst metal. Even when the experiment was performed, the shape of each catalytic metal film did not deteriorate.

<Example 2>
FIG. 2 shows another embodiment of the hydrogen detection element using the catalyst film monolayer of the present invention.
A plurality of openings made of a resist pattern of 50 μm ^□ are provided on the glass substrate 20 over the entire surface of the substrate 20 at intervals of a maximum of 30 μm using a photolithography technique, and a palladium film having a thickness of 80 nm is formed using a well-known vacuum evaporation method. After the deposition, an unnecessary resist pattern and palladium film are removed by a lift-off method to form a 50 μm ^square palladium pattern 21, thereby completing the hydrogen detection element 22.
As a result of measuring and observing the surface of the palladium pattern 21 by performing the same hydrogen exposure experiment (hydrogen concentration of hydrogen-containing air as 5%) on the completed hydrogen detection element 22, the surface roughness was slightly generated. However, no film peeling was observed.

At the same time, light with a wavelength of 740 nm was irradiated toward the substrate from the surface side, and the change in the amount of reflected light was observed, but it was confirmed that the amount of reflected light was attenuated about 2 seconds after exposure to hydrogen-containing air. It was. After about 20 seconds, it was confirmed that it attenuated to 1/3 of the amount of reflected light before exposure.
Moreover, although the example which used the palladium film | membrane was described in the said Example, even if it performed the said hydrogen exposure experiment using the platinum film | membrane, film | membrane shape degradation, such as film | membrane peeling, was not seen.

<Example 3>
FIG. 3 shows an embodiment of the hydrogen detection element having a special structure in which the catalyst film / metal oxide bilayer structure region and the catalyst film single film region of the present invention coexist.
A plurality of openings made of a resist pattern of 30 μmφ are provided on the entire surface of the glass substrate 30 at intervals of 50 μm on the glass substrate 30 using a photolithography technique, and a vanadium film having a film thickness of 100 nm is coated using a well-known vacuum deposition method. After the deposition, an unnecessary resist pattern and vanadium film are removed by a lift-off method.

By performing heat treatment at about 600 ° C. in an oxygen atmosphere, a large number of vanadium oxide patterns 31 having a size of 30 μmφ are formed on the glass substrate 30.
At this time, the cross section of the vanadium oxide film 31 indicated by the broken line AA ′ has a convex portion formed by the vanadium oxide pattern 31 as shown in FIG. 3B, and the film thickness of the vanadium oxide pattern 31 is measured. As a result, it was confirmed that the thickness was about 250 nm.
A hydrogen detection element in which a catalyst film / metal oxide bilayer structure region and a catalyst film single film region coexist by depositing a platinum film 32 having a film thickness of 30 nm on the entire surface of the substrate 30 using a known vacuum deposition method. 33 is completed.

  The hydrogen detection element of the present invention is characterized in that a catalyst film single film region excellent in high-speed response and a catalyst film / metal oxide two-layer structure region capable of low concentration detection are mixed, so that the detection location, etc. This is a hydrogen detection element that can be applied to cases where there is no limitation on the application range of the sensor and hydrogen detection is required from a low concentration to a high concentration range.

<Example 4>
FIG. 4 shows an embodiment of a hydrogen detecting element having a special uneven shape by the catalyst film / metal oxide bilayer structure of the present invention.
After depositing a molybdenum film having a thickness of 100 nm on the glass substrate 40 using a vacuum deposition method, a heat treatment at about 650 ° C. is performed in a normal air atmosphere to form a molybdenum oxide film 41 on the entire surface of the glass substrate 40. Form. At this time, as a result of measuring the film thickness of the molybdenum oxide film 41, it was confirmed to be about 250 nm.

Using photolithography technology, openings made of a regular hexagonal resist pattern having a diagonal length of 20 μm are formed at intervals of a maximum of 20 μm.
After depositing a molybdenum film having a thickness of 100 nm using a vacuum deposition method, unnecessary resist patterns and molybdenum films are removed by a lift-off method to form a regular hexagonal molybdenum pattern having a diagonal length of 20 μm.
By performing heat treatment at about 650 ° C. again in an air atmosphere, a regular hexagonal molybdenum oxide pattern 42 bonded to the molybdenum oxide film 41 is formed.
At this time, in the cross section of the region where the molybdenum oxide film 41 and the regular hexagonal molybdenum oxide pattern 42 indicated by the broken line BB ′ overlap, the unevenness by the molybdenum oxide film as shown in FIG. 4B is formed. ing.

The other hydrogen detection element 44 having a special structure is completed by depositing a palladium film 43 having a thickness of 10 nm on the entire surface of the substrate 40 using a known vacuum deposition method.
In the hydrogen detection element of the present invention, the catalyst film / metal oxide bilayer structure region, which is the hydrogen detection region, is also formed on the side surface of the regular hexagonal molybdenum oxide pattern 42. The sensitivity and response speed are further improved as compared with a normal planar hydrogen detection element fabricated on a transparent substrate.

  Hydrogen exposure experiment (3 levels of hydrogen concentration of hydrogen-containing air: 0.2%, 0.5%, 1%) while irradiating light of 1.2μm wavelength toward the substrate from the surface side to the completed hydrogen detection element 44 As a result of observing the change in the amount of transmitted light at this time, it was confirmed that the transmitted light was attenuated immediately after exposure to hydrogen-containing air. Furthermore, it was also confirmed that the attenuation of transmitted light at each hydrogen concentration increased proportionally as the concentration increased.

<Example 5>
FIG. 5 shows an embodiment of another hydrogen detection element having a special structure in which the catalyst film / metal oxide bilayer structure region, the catalyst film single film region, and the region where the glass substrate is exposed are mixed.
A plurality of openings made of a resist pattern of 30 μmφ are provided over the entire surface of the glass substrate 50 at a maximum interval of 30 μm on the glass substrate 50 using a photolithography technique, and a tungsten film having a thickness of 50 nm is formed using a well-known vacuum evaporation method. After deposition, an unnecessary resist pattern and tungsten film are removed by a lift-off method.

By performing heat treatment at about 500 ° C. in an oxygen atmosphere, a plurality of tungsten oxide patterns 51 having a size of 30 μmφ are formed on the glass substrate 50.
An opening made of a resist pattern having a diameter of 5 μm and a diameter of 5 μm larger than that of the previously formed circular tungsten oxide pattern 51 is formed on the outer peripheral portion of each tungsten oxide pattern 51 on the glass substrate 50 using photolithography technology. .
After depositing a platinum film having a thickness of 20 nm using a well-known vacuum deposition method, an unnecessary resist pattern and platinum film are removed by a lift-off method to form a palladium pattern 52, whereby a catalyst film / metal oxide is formed. The hydrogen detection element 53 in which the two-layer structure region, the catalyst film single film region, and the region where the glass substrate surface is exposed is mixed is completed.
It was confirmed that this element 53 also showed good hydrogen sensitivity as in the above example. An example in which a hydrogen detection device is constructed using this element will be described later in <Example 7>.

<Example 6>
FIG. 6 shows an example of another hydrogen detection element having a structure in which a metal oxide formed on a glass substrate is made of fine crystal grains and a catalyst film is deposited and formed on the entire upper surface thereof.
Tungsten oxide crystal grains having a size of 0.1 to 5 μm are deposited on the glass substrate 60 to form a tungsten oxide layer 61 having minute irregularities and a space between the crystal grains. As this formation method, for example, after applying an organic solvent containing tungsten oxide crystal grains, there is a method of performing an annealing process at about 400 ° C. in a nitrogen atmosphere.
Next, a palladium film 62 having a thickness of 20 nm is deposited on the entire surface of the substrate using a well-known vacuum deposition method, whereby a catalyst film / metal oxide bilayer structure in which tungsten oxide, which is a metal oxide, consists of fine crystal grains. The hydrogen detection element 63 is completed.
In the hydrogen detection element 63 of the present invention, the catalyst film / metal oxide two-layer structure region, which is a hydrogen sensitive region, has an extremely large area, so that the normal hydrogen detection element manufactured on the same size transparent substrate is used. In comparison, the detection sensitivity and response speed are significantly improved.

A hydrogen exposure experiment (hydrogen concentration of hydrogen-containing air is 0.5%) was performed while irradiating the completed hydrogen detection element 63 with light having a wavelength of 1.2 μm toward the substrate from the surface side. As a result of observing the change in the amount of reflected light, it was confirmed that the transmitted light and the reflected light rapidly attenuated immediately after exposure to hydrogen-containing air. After about 5 seconds, it was confirmed that the light quantity was stabilized by attenuation to 1/3 of the transmitted light quantity before exposure and 1/4 of the reflected light quantity. Furthermore, when it was returned to normal air, each light quantity began to recover rapidly, and returned to its original value 20 seconds after exposure to normal air.
In Example 6 described above, the metal oxide layer is formed by applying an organic solvent containing tungsten oxide crystal grains and annealing treatment. In addition, any other method such as a CVD method or a sputtering method may be used. Needless to say, it may be formed. Further, it goes without saying that the same effect can be obtained by using a metal oxide layer made of molybdenum oxide crystal grains and vanadium oxide crystal grains.

In the above embodiments relating to the hydrogen detection element, the case where a glass substrate is used as the transparent substrate has been described, but it goes without saying that a substrate made of another transparent material such as plastic may be used.
In addition, in the hydrogen detection elements of various shapes manufactured in the above embodiments, examples of using tungsten oxide, vanadium oxide, and molybdenum oxide are described, but each shape has its own characteristics described in the above embodiments. In addition to the metal oxide, any metal oxide selected from tungsten oxide, molybdenum oxide, and vanadium oxide may be used, and any catalyst film selected from palladium or platinum may be used. It may be used.

<Example 7>
Next, an embodiment in which the hydrogen detection element 53 of the present invention is applied to a hydrogen detection apparatus configured by applying an OTDR (optical timedomain reflectometer) method which is a kind of general remote sensing using an optical fiber is shown in FIG. 7 shows.
OTDR is generally known to be able to measure the loss distribution of connection loss in a fiber by detecting the break point of an optical fiber cable and detecting backscattered light, and is widely used in the field of maintenance of optical communication cables. It has been broken.

  In the hydrogen detection apparatus equipped with the hydrogen detection element 53 of the present invention, a plurality of optical fibers and optical fibers are connected using a plurality of connection connectors equipped with the hydrogen detection element 53 of the present invention. One optical signal propagation path using a plurality of connection connectors is configured. For example, by appropriately laying this in the hydrogen flow path region, hydrogen can be individually detected for each connector by the hydrogen detection element mounted on each connection connector. In this case, the location of hydrogen leakage can be identified.

The principle of operation of the hydrogen detector of the present invention will be described with reference to FIG.
The semiconductor laser 71 is driven by a pulse current controlled by a signal from the timing generator 70, and pulsed light is generated from the semiconductor laser with a constant pulse width.
This pulsed light is emitted through the coupler 72 to the optical fiber 74A connected to the input / output connector 73 of the OTDR.
The light pulse incident on the optical fiber 74A is propagated forward through the optical fiber 74A.
The propagating light pulse plays a role of connecting the optical fiber 74A and the optical fiber 74B, is equipped with the hydrogen detection element 53 of the present invention, and is intended to bring outside air into contact with the hydrogen detection element 53. The hole reaches the hydrogen detecting element mounting connector 75 provided on the outer peripheral portion.
Since the hydrogen detection element mounting connector 75 is mounted with the hydrogen detection element 53 described in the sixth embodiment, the optical pulse that has passed through the optical fiber 74A is reflected and returned to the OTDR. A part of the light pulse transmitted through the detection element 53 can be propagated to the front optical fiber 74B.

Furthermore, the detection area can be further expanded by alternately connecting the hydrogen detection element mounting connector and the optical fiber in front of the connector.
The time until the light pulse incident on the optical fiber returns to the OTDR is proportional to the distance to the reflection point, and the returned light is incident on the photodetector through the coupler 72 to be electrically Converted to a signal.
This signal is amplified by an amplifier 76 and then converted to a digital signal by an analog-digital converter 77 to display the light intensity.

  Using the hydrogen detection device produced in this example, an optical signal propagation path constituted by the optical fiber and the hydrogen detection element mounting connector, for example, a petrochemical plant or a device that handles hydrogen, or hydrogen as fuel By properly laying the unit in the hydrogen gas and hydrogen gas flow paths, such as in automobiles, the hydrogen leak can be detected safely and quickly, and the location of the leak can be identified very easily. It becomes.

<Example 8>
Next, FIG. 8 shows an embodiment in which the hydrogen detection element 22 of the present invention is applied to another hydrogen detection apparatus using an optical fiber. FIG. 8 shows an example of a transmission type.
The light from the light source at a distant place is introduced into the hydrogen flow path by the optical fiber 80A, and the light emitted from the optical fiber 80A is converted into a parallel light beam by the optical lens 81 and then into the hydrogen flow path. Is projected onto the hydrogen detection element 22 of the present invention provided in The light that has passed through the hydrogen detection element 22 is incident on the optical fiber 80B through the condenser lens 82, and is incident on the photodetector 83 at a location away through the optical fiber 80B.
The hydrogen detection element 22 of the present invention has a shape in which a palladium pattern is formed only on the front surface side of a glass substrate that is a transparent substrate. Since it is doubled, the sensitivity can be further increased.

<Example 9>
Next, FIG. 9 shows an embodiment in which the hydrogen detection element 13 of the present invention is applied to another hydrogen detection apparatus using an optical fiber. FIG. 9 shows an example of a reflection type.
The back side of the hydrogen detection element 13 is directly connected to the exit end of the optical fiber 90, and the exit end is introduced into the hydrogen flow path. The light emitted from the semiconductor laser 91 in the hydrogen detector main body 94 is emitted to the optical fiber 90 connected to the input / output connector 93 through the coupler 92, and hydrogen connected to the emission end of the optical fiber 90. The detection element 13 is reached. The light is reflected with the palladium surface provided on the surface of the hydrogen detection element 13 as a reflection surface, and is introduced into the optical fiber 90 again. The returned light is incident on the photodetector 94 through the coupler 92.

Since the hydrogen detection device manufactured in this example can exchange a hydrogen detection signal with one optical fiber, a portable hydrogen detection device can be easily manufactured.
Further, in the hydrogen detection device, as shown in FIG. 9B, the hydrogen detection element provided at the emission end of the optical fiber includes a reflecting mirror that reflects light in a form having a space of about 1 to 3 mm. As a result, the reflected light intensity can be further increased, so that a minute change in the reflected light can be detected quickly, and the hydrogen detection performance is improved.
The present invention can be used for a hydrogen leak detector, a detection system, or the like that prevents an explosion accident due to hydrogen leak in a petrochemical plant, a device that handles hydrogen, or an apparatus such as an automobile that uses hydrogen as fuel.

  In addition, the description of the code | symbol in this-application drawing is as follows.

DESCRIPTION OF SYMBOLS 10 ... Glass substrate, 11 ... Tungsten oxide film, 12 ... Palladium pattern, 13 ... Hydrogen detection element, 20 ... Glass substrate, 21 ... Palladium pattern, 22 ... Hydrogen detection element,
DESCRIPTION OF SYMBOLS 30 ... Glass substrate, 31 ... Vanadium oxide pattern, 32 ... Platinum film, 33 ... Hydrogen detection element, 40 ... Glass substrate, 41 ... Tungsten oxide film, 42 ... Tungsten oxide pattern, 43 ... Palladium film, 44 ... Hydrogen detection element, DESCRIPTION OF SYMBOLS 50 ... Glass substrate, 51 ... Tungsten oxide pattern, 52 ... Platinum pattern, 53 ... Hydrogen detection element, 60 ... Glass substrate, 61 ... Tungsten oxide layer, 62 ... Palladium film, 63 ... Hydrogen detection element, 70 ... Timing generator, 71 ... Semiconductor laser, 72 ... Coupler, 73 ... Input / output connector, 74A, 74B ... Optical fiber, 75 ... Hydrogen detection element mounting connector, 76 ... Amplifier, 77 ... Analog to digital converter, 80A, 80B ... Optical fiber 81 ... Optical lens, 82 ... Condensing lens, 83 ... Photo detector, 90 ... Optical fiber 91, semiconductor laser, 92 ... coupler, 93 ... input / output connector, 94 ... photodetector, 95 ... hydrogen detector main body.

The figure which shows the 1st Example of this invention. The figure which shows the 2nd Example of this invention. The figure which shows the 3rd Example of this invention. The figure which shows the 4th Example of this invention. The figure which shows the 5th Example of this invention. The figure which shows the 6th Example of this invention. The figure which shows the 7th Example of this invention. The figure which shows the 8th Example of this invention. The figure which shows the 9th Example of this invention.

Claims (17)

A first hydrogen reaction film deposited on the transparent substrate and having optical characteristics changed by reaction with hydrogen; and a second hydrogen reaction film deposited on the first hydrogen reaction film and having a property of occluding and releasing hydrogen. A hydrogen reaction membrane,
The first hydrogen reaction film comprises a plurality of crystal grains in contact with the transparent substrate, and the second hydrogen reaction film is deposited on each of the crystal grains. Detection type hydrogen detection element. A first hydrogen reaction film whose optical properties change by reaction with hydrogen;
A second hydrogen reaction film having a property of occluding and releasing hydrogen is laminated on a transparent substrate;
In the hydrogen detection element that detects a change in the amount of reflection and transmission of light irradiated on the surface of the transparent substrate,
At least one of the first and second hydrogen reaction films is processed into a polygonal or circular pattern, and the diagonal line or the diameter thereof is 70 μm or less. . The first hydrogen reaction membrane is processed into a polygonal or circular pattern,
2. The photodetection type hydrogen according to claim 1, wherein the second hydrogen reaction film is formed of a continuous single-leaf film and is formed on the first hydrogen reaction film or the transparent substrate. Detection element. The first hydrogen reaction membrane is processed into a polygonal or circular pattern,
The second hydrogen reaction film is formed so as to cover an upper end surface and a side surface of the first hydrogen reaction film, and is processed into a pattern having the same shape as the first hydrogen reaction film, and a part thereof is The photodetection type hydrogen detection element according to claim 1, wherein each of the processed patterns extends on a transparent substrate and is spaced apart. A first hydrogen reaction film formed on the transparent substrate, the optical properties of which change by reaction with hydrogen;
A first hydrogen reaction film formed on the first hydrogen reaction film and processed into a polygonal or circular pattern;
2. The photodetection type hydrogen detection element according to claim 1, further comprising a second hydrogen reaction film formed on the first hydrogen reaction film or the transparent substrate and made of a continuous single-leaf film. . A second hydrogen reaction film having a property of occluding and releasing hydrogen is deposited on a transparent substrate;
In the hydrogen detection element that detects a change in the amount of reflection and transmission of light irradiated on the surface of the transparent substrate,
The second hydrogen reaction film has a polygonal or circular pattern, and its diagonal line or its diameter is 70 μm or less.   2. The photodetection type hydrogen detection element according to claim 1, wherein the first hydrogen reaction film and the second hydrogen reaction film are also formed on a back surface side of the transparent substrate.   The photodetection type hydrogen detection element according to claim 1, wherein the first hydrogen reaction film is made of a metal oxide.   2. The photodetection type hydrogen detection element according to claim 1, wherein the first hydrogen reaction film is made of an oxide containing tungsten (W) as a main component.   2. The photodetection type hydrogen detection element according to claim 1, wherein the first hydrogen reaction film is made of an oxide containing molybdenum (Mo) as a main component.   2. The photodetection type hydrogen detection element according to claim 1, wherein the first hydrogen reaction film is made of an oxide containing vanadium (V) as a main component.   The photodetection type hydrogen detection element according to claim 1, wherein the second hydrogen reaction film is made of a catalyst metal.   2. The photodetection type hydrogen detection element according to claim 1, wherein the second hydrogen reaction film is made of palladium (Pd) or an alloy containing palladium as a main component.   2. The photodetection type hydrogen detection element according to claim 1, wherein the second hydrogen reaction film is made of platinum (Pt) or an alloy containing platinum as a main component.   2. The light according to claim 1, wherein the second hydrogen reaction material is present in a film shape on the transparent substrate including a region having a convex shape made of the first hydrogen reaction material. Detection type hydrogen detection element.   A hydrogen detection apparatus comprising an optical fiber, wherein the light detection type hydrogen detection element according to claim 1 is connected to a light emitting end of the optical fiber. In the hydrogen detection apparatus including a plurality of optical fibers, the light detection type hydrogen detection element according to claim 1 is provided between the optical fibers so that light passes through the front and back surfaces of the element. To detect hydrogen.

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