JP7281127B2 - Gas sensor with infrared light source and infrared light source - Google Patents

Description

The present invention relates to an infrared light source and a gas sensor with an infrared light source.

In order to detect target gases such as carbon monoxide, infrared gas sensors, such as those of the non-dispersive infrared spectroscopy (NDIR) type, are used. A gas sensor using infrared rays identifies and quantifies a gas to be detected by utilizing the property that infrared rays are absorbed by exciting the vibration of molecules contained in the gas to be detected. Such a gas sensor uses an infrared light source that emits infrared rays for irradiating the gas to be detected.

In order to detect a specific gas to be detected with high accuracy and sensitivity, it is desirable to configure the infrared light source with an infrared emitter that has narrow-band infrared emission characteristics that can preferentially excite the vibration of specific molecules. be As an infrared emitter having narrow-band infrared emission characteristics, for example, an infrared absorbing (emitting) body disclosed in Patent Document 1 is expected. The infrared absorbing (light emitting) body of Patent Document 1 is provided with a metal fine structure layer that causes localized surface plasmon resonance on a substrate, thereby increasing the emission intensity of infrared rays having a specific wavelength that satisfies the resonance conditions of localized surface plasmon resonance. can be enhanced.

JP 2020-134337 A

For example, when the infrared absorbing (light emitting) body of Patent Document 1 is used as an infrared light source, a heating source for heating the infrared absorbing (light emitting) body is provided on the side of the substrate opposite to the side on which the metal fine structure layer is provided. be done. In that case, the heat from the heating source is transferred to the infrared absorbing (emitting) body through the substrate. It may take a long time to stably heat the infrared absorbing (emitting) body. Along with this, it may take a long time to stably radiate infrared rays after starting heating of the infrared light source. As described above, not only the infrared absorbing (emitting) body of Patent Document 1 but also an infrared light source using an infrared emitting body having an infrared emitting structure provided on a substrate heats the infrared light source by thermal diffusion into the substrate. It may take a long time for infrared rays to be emitted stably after the start of

SUMMARY OF THE INVENTION It is an object of the present invention to provide an infrared light source capable of stably emitting infrared light within a short period of time from the start of heating, and a gas sensor equipped with the infrared light source.

The infrared light source of the present invention comprises a substrate, an infrared light emitter provided on the substrate and absorbing heat to emit infrared light, and provided between the substrate and the infrared light emitter to heat the infrared light emitter. and a heating layer, wherein the infrared light source is provided between the substrate and the heating layer, and a heat conduction suppression layer that suppresses heat conduction between the substrate and the heating layer. and an insulating layer provided between the heating layer and the infrared emitter for electrically insulating between the heating layer and the infrared emitter.

In addition, the infrared emitter comprises a metal microstructure layer capable of absorbing heat and causing localized surface plasmon resonance, a dielectric layer provided below the metal microstructure layer, and the metal microstructure layer. and a metal layer provided under the dielectric layer so as to sandwich the dielectric layer therebetween.

Moreover, it is preferable that the heat conduction suppressing layer contains a heat-resistant organic polymer material.

Moreover, it is preferable that the heat conduction suppressing layer has a film thickness of 500 nm or more and 5000 nm or less.

Moreover, it is preferable that the insulating layer contains an inorganic insulating material.

Moreover, it is preferable that the insulating layer has a film thickness of 50 nm or more and 100 nm or less.

A gas sensor according to the present invention includes the infrared light source.

According to the present invention, it is possible to provide an infrared light source capable of stably emitting infrared rays in a short period of time from the start of heating, and a gas sensor equipped with the infrared light source.

1 is a schematic diagram of a gas detector including a gas sensor with an infrared light source according to an embodiment of the invention; FIG. It is a sectional view showing typically a section structure of an infrared light source concerning one embodiment of the present invention.

Hereinafter, an infrared light source and a gas sensor including an infrared light source according to an embodiment of the present invention will be described with reference to the drawings. However, the following embodiments are merely examples, and the infrared light source and gas sensor of the present invention are not limited to the following embodiments.

The infrared light source 1 of this embodiment is a light source capable of emitting infrared rays. An example in which the infrared light source 1 is applied to the light source of a gas sensor N provided in a gas detector M as shown in FIG. 1 will be described below. However, the infrared light source 1 is not limited to gas sensors, and can be applied to other uses that require infrared irradiation.

A gas detector M to which the infrared light source 1 of this embodiment is applied is used to detect a gas to be detected. The gas to be detected by the gas detector M is not particularly limited, and examples thereof include carbon monoxide, carbon dioxide, methane, butane, isobutane, water, ammonia, sulfur dioxide, sulfur trioxide, Gases having absorption peaks in the infrared wavelength region, such as hydrogen sulfide, nitrous oxide, acetone, ozone, sulfur hexafluoride, octafluorocyclopentene, and hexafluoro-1,3-butadiene, are exemplified.

The gas detector M, as shown in FIG. 1, has a gas sensor N for detecting a gas to be detected. The gas detector M optionally includes an operation unit M1 (for example, operation buttons) for operating the gas sensor N and a display unit M2 (for example, a liquid crystal display) for displaying detection results obtained by the gas sensor N. there is The gas detector M is powered by a power source (not shown) such as an internal battery or an external power source.

The gas sensor N detects the detection target gas by irradiating the detection target gas with the infrared rays L and measuring the absorption intensity (attenuation intensity) of the infrared rays absorbed by the detection target gas. The gas sensor N can be configured, for example, as the well-known non-dispersive infrared spectroscopy (NDIR) type. In this embodiment, as shown in FIG. 1, the gas sensor N includes a housing N1 having an internal space V, an infrared light source 1 that emits infrared rays L inside the housing N1, and infrared rays L emitted from the infrared light source 1. , an infrared detector N3 for detecting infrared rays L, and a circuit portion N4 for controlling the infrared light source 1 and the infrared detector N3. The gas sensor N has an infrared light source 1, a reflecting structure N2, an infrared detector N3, and a circuit portion N4 integrally provided in a housing N1 to form a module that can be handled as a single unit. However, in the gas sensor N, for example, the circuit part N4 may be provided separately from the housing N1, and the configuration is not limited to the illustrated example.

In this embodiment, the housing N1 is a member that houses the infrared light source 1, the reflecting structure N2, the infrared detector N3, and the circuit section N4, and supplies the internal space V with the gas to be detected. As shown in FIG. 1, the housing N1 is formed in a tubular shape extending in a direction connecting the infrared light source 1 and the infrared detector N3 (horizontal direction in FIG. 1), and an internal space V is provided therein. . Further, the housing N1 includes a gas introduction portion (not shown) for introducing the detection target gas into the internal space V and a gas discharge portion (not shown) for discharging the detection target gas from the internal space V. there is In the housing N1, the detection target gas is introduced from the gas introduction part, the detection target gas is supplied into the internal space V, and the detection target gas is discharged from the gas discharge part. The housing N1 is not particularly limited, and is formed of, for example, a resin material. Although the housing N1 is formed in a cylindrical shape extending in one direction in this embodiment, it may be formed in another shape such as a substantially rectangular parallelepiped shape.

In this embodiment, the infrared light source 1 emits infrared rays L that can be used to detect the gas to be detected. When applied to the gas sensor N, the infrared light L emitted by the infrared light source 1 may include at least light having the wavelength of the absorption peak in the absorption spectrum of the gas to be detected, and may be monochromatic light of that wavelength. , may be light in a wide wavelength range including the wavelength. The infrared light source 1, as shown in FIG. 1, is communicatively connected to the circuit portion N4 and its output is controlled by the circuit portion N4. The infrared light source 1 may be configured to emit continuous light or pulsed light, for example. The infrared light source 1 can radiate infrared rays of a required wavelength by appropriately selecting the type of the infrared light emitter 3, which will be described later. Details of the infrared light source 1 will be described later.

The reflective structure N2 reflects the infrared rays L emitted from the infrared light source 1 or the infrared rays L reflected from other parts of the reflective structure N2 in the interior space V of the housing N1, and further reflects the infrared rays L. Infrared radiation L is directed to part of structure N2 or to infrared detector N3. In this embodiment, the reflecting structure N2 is provided on the inner surface of the housing N1 adjacent to the internal space V, as shown in FIG. The reflecting structure N2 is not particularly limited, and a known reflecting mirror or the like can be used.

The infrared detector N3 detects the infrared rays L and measures the intensity of the infrared rays L. As shown in FIG. 1, the infrared detector N3 detects the infrared rays L emitted from the infrared light source 1 and propagated through the internal space V of the housing N1. Infrared detector N3 is aligned to detect infrared radiation L emitted from infrared light source 1 and/or reflected infrared radiation L from reflecting structure N2. The infrared detector N3 is communicatively connected to the circuit portion N4 and transmits a signal corresponding to the detected infrared rays to the circuit portion N4. The infrared detector N3 is not particularly limited, and a known infrared detector can be adopted.

Circuit portion N4 is communicatively connected to infrared light source 1 and infrared detector N3 and controls infrared light source 1 and infrared detector N3, as shown in FIG. In addition, the circuit unit N4 compares the intensity of the infrared rays L emitted from the infrared light source 1 and the intensity of the infrared rays L measured by the infrared detector N3 to determine the presence or absence of the gas to be detected, or detect it. Calculate the concentration of the target gas. The circuit portion N4 can be configured by, for example, a known central processing unit (CPU).

As shown in FIG. 2, the infrared light source 1 includes a substrate 2, an infrared emitter 3 provided on the substrate 2 and absorbing heat to emit infrared rays, and provided between the substrate 2 and the infrared emitter 3. and a heating layer 4 for heating the infrared emitter 3 . In the infrared light source 1, heat is applied to the infrared emitter 3 by the heating layer 4, and the infrared emitter 3 absorbs the heat and emits infrared rays, thereby radiating infrared rays.

Substrate 2 supports a laminate structure including infrared emitters 3, heating layer 4, and additional layers described below. The substrate 2 is not particularly limited as long as it can support this laminated structure, and can be made of a semiconductor material, a dielectric material, or a metal material. For example, substrate 2 can be a silicon substrate, a sapphire substrate, or a glass substrate. The thickness of the substrate 2 is not particularly limited, but from the viewpoint of strength, it is, for example, 0.3 mm or more, preferably 0.5 mm or more, more preferably 0.7 mm or more, and even more preferably 0.9 mm. From the viewpoint of ease of handling, the thickness is set to 2.0 mm or less, preferably 1.8 mm or less, more preferably 1.6 mm or less, and even more preferably 1.4 mm or less.

The structure of the infrared emitter 3 is not particularly limited as long as it can absorb heat and emit infrared rays. In this embodiment, as shown in FIG. 2, the infrared emitter 3 is provided in a metal microstructure layer 31 capable of absorbing heat and causing localized surface plasmon resonance, and in a layer below the metal microstructure layer 31. It comprises a dielectric layer 32 and a metal layer 33 provided below the dielectric layer 32 so as to sandwich the dielectric layer 32 between the metal microstructure layer 31 . When the infrared emitter 3 absorbs heat, localized surface plasmon resonance occurs and the infrared emissivity increases. In particular, in the infrared emitter 3, the metal microstructure layer 31 and the metal layer 33 are stacked with the dielectric layer 32 interposed therebetween, thereby enhancing the localized surface plasmon resonance. This is because when heat is absorbed and localized surface plasmon resonance occurs, a strong electric field is localized in the dielectric layer 32 laminated between the metal microstructure layer 31 and the metal layer 33. , is thought to be due to the enhancement of the localized surface plasmon resonance under the influence of the localized electric field. As shown in the figure, the infrared light emitter 3 contains chromium (Cr) or titanium for the purpose of ensuring adhesion between the respective layers of the metal fine structure layer 31, the dielectric layer 32 and the metal layer 33. An adhesion layer A1 such as (Ti) may be provided (in the example shown, provided only between the dielectric layer 32 and the metal layer 33).

The metal microstructure layer 31 is a layer that can absorb heat and cause localized surface plasmon resonance. When heat is applied to the metal fine structure layer 31 , plasmon oscillation of free electrons is excited on the surface of the metal fine structure layer 31 , and free electron density is generated in the metal fine structure layer 31 . A polarized state occurs in When the wavelength of the infrared rays emitted by the absorption of heat and the dielectric constant of the metal microstructure layer 31 mutually satisfy the resonance condition, the polarization generated in the metal microstructure layer 31 by heat becomes very large, and the metal microstructure layer 31 localized surface plasmon resonance occurs. In the infrared emitter 3 , localized surface plasmon resonance occurs in the metal microstructure layer 31 , thereby increasing the infrared emissivity that satisfies the resonance condition. The method of forming the metal fine structure layer 31 is not particularly limited as long as it can absorb heat and cause localized surface plasmon resonance. can be formed.

The structure of the metal fine structure layer 31 is not particularly limited as long as it can generate localized surface plasmon resonance. The metal microstructure layer 31 may have, for example, a nanodisk array structure in which a plurality of island-shaped metal bodies are two-dimensionally distributed, or a plurality of holes are two-dimensionally distributed in the metal layer. It may also have a nanohole array structure. In this embodiment, as shown in FIG. 2, the metal microstructure layer 31 has a plurality of substantially disk-shaped metal microstructures that are substantially circular when viewed from above in a direction perpendicular to the surface of the substrate 2. It has a body 31a. The plurality of metal microstructures 31a are arranged on the dielectric layer 32 with a space therebetween.

The shape and size of the metal microstructure 31a are not particularly limited, and can be appropriately set so as to cause localized surface plasmon resonance in the metal microstructure 31a when heat is absorbed. For example, with respect to the shape, the wavelength of the infrared rays emitted due to localized surface plasmon resonance changes according to the shape of the metal microstructure 31a. By making the shape of the metal microstructure 31a, for example, rod-like or plate-like, the wavelength of infrared rays emitted due to localized surface plasmon resonance is shifted to the longer wavelength side. Therefore, the metal microstructure 31a has a substantially disk shape as in the present embodiment, a substantially rectangular plate shape, or a substantially hemispherical shape, depending on the wavelength of infrared rays emitted due to localized surface plasmon resonance. , a substantially bar-like shape, or any other shape can be selected. As for the size, for example, the wavelength of the infrared rays emitted due to localized surface plasmon resonance changes according to the size of the metal microstructure 31a. As the metal microstructure 31a becomes larger (for example, as the diameter of the metal microstructure 31a becomes larger), the wavelength of infrared rays emitted due to localized surface plasmon resonance shifts to the longer wavelength side. Therefore, the size of the metal microstructure 31a can be appropriately selected according to the wavelength of infrared rays emitted due to localized surface plasmon resonance.

The metal microstructure 31a is not particularly limited, but for example, when the dielectric layer 32 contains an organic polymer material as described later, the radiation intensity of infrared rays caused by the vibration of molecular bonds contained in the organic polymer material is reduced. From the viewpoint of increasing the diameter, for example, it has a diameter of 1000 nm or more and 5000 nm or less, preferably 1000 nm or more and 2000 nm or less, more preferably 1000 nm or more and 1800 nm or less. It is even more preferred to have a diameter of 1600 nm or less.

The thickness of the metal microstructure layer 31 is not particularly limited as long as it can generate localized surface plasmon resonance by absorbing heat. From the viewpoint of enhancing localized surface plasmon resonance, the thickness of the metal fine structure layer 31 is preferably 10 to 200 nm, more preferably 30 to 100 nm, and even more preferably 35 to 75 nm. Preferably, it is most preferably between 40 nm and 70 nm.

The constituent metal of the metal fine structure layer 31 is not particularly limited as long as it is made of a metal that causes localized surface plasmon resonance by absorbing heat. Metal fine structure layer 31 contains, for example, one or more selected from the group consisting of gold (Au), silver (Ag), copper (Cu), platinum (Pt), and palladium (Pd). be done. The metal fine structure layer 31 is selected from the group consisting of gold (Au) and silver (Ag), for example, from the viewpoint of surface chemical stability and the viewpoint of increasing the infrared emissivity due to localized surface plasmon resonance. It is preferably composed of one or two or more. Gold (Au) is preferable from the viewpoint of surface chemical stability, and silver (Ag) is preferable from the viewpoint of increasing the infrared emissivity due to localized surface plasmon resonance.

The dielectric layer 32 is laminated between the metal microstructure layer 31 and the metal layer 33 as shown in FIG. It is a layer that can exist. Dielectric layer 32 is formed as a continuous film within the surface of metal layer 33 . The dielectric layer 32 is not particularly limited, and can be formed by known film formation techniques such as resistance heating vapor deposition, sputtering, electron beam vapor deposition, and spin coating.

If the dielectric layer 32 is laminated between the metal fine structure layer 31 and the metal layer 33 and can cause localized surface plasmon resonance in the metal fine structure layer 31, its constituent material is particularly limited. never. Dielectric layer 32 may be, for example, silicon oxide (such as SiO ₂ ), aluminum oxide (such as Al ₂ O ₃ ), silicon nitride (such as Si ₃ N ₄ ), silicon (Si), zirconium oxide (such as ZrO ₂ ), oxide It can contain one or more selected from the group consisting of titanium (TiO ₂ etc.). From the viewpoint of suppressing the disappearance of localized surface plasmons generated in the metal microstructure layer 31, the dielectric layer 32 is made of silicon oxide ( _SiO2, etc.), aluminum oxide ( _{Al2O3 ,} etc.), silicon nitride ( _Si3N ). ₄ , etc.) is preferably composed of one or more selected from the group consisting of:

The film thickness of the dielectric layer 32 containing the inorganic material described above is not particularly limited, but the localized surface plasmon generated in the metal fine structure layer 31 is suppressed from being affected by the metal layer 33 and disappearing. 10 nm or more, more preferably 20 nm or more, even more preferably 30 nm or more, and most preferably 50 nm or more. In addition, the thickness of the dielectric layer 32 is preferably 200 nm or less, more preferably 150 nm or less, from the viewpoint of enhancing the localized surface plasmon resonance generated by the metal microstructure layer 31 and thereby improving the infrared emissivity. is more preferably 100 nm or less, and most preferably 80 nm or less.

In addition to the materials described above, the dielectric layer 32 may include an organic polymer material having molecular bonds capable of absorbing heat, exciting vibration, and emitting infrared rays due to the vibration. . As a result, when heat is absorbed by the infrared emitter 3, infrared radiation is generated due to excitation of molecular vibration. The wavelength width of the emission peak caused by the excitation of the vibration of the molecular bond contained in the organic polymer material (for example, the emission peak caused by the vibration of the C=O bond) is the wavelength width of the emission peak caused by localized surface plasmon resonance. small compared to Therefore, by utilizing the radiation peak resulting from the excitation of this molecular vibration, it is possible to realize narrow-band infrared radiation characteristics.

In addition, radiation due to localized surface plasmon resonance is generated at the same time as radiation due to excitation of molecular vibration, so that the infrared emissivity due to excitation of molecular vibration is increased. Therefore, the infrared emitter 3 can emit infrared light with a narrow wavelength width and high emissivity by laminating the dielectric layer 32 containing an organic polymer material between the metal fine structure layer 31 and the metal layer 33. can be done. In particular, the closer the wavelength of the emission peak caused by localized surface plasmon resonance to the wavelength of the emission peak caused by the excitation of molecular vibration, the higher the infrared emissivity of the emission caused by the excitation of molecular vibration. It is considered that this is due to strong coupling between the molecular vibration in the dielectric layer 32 and the localized surface plasmon resonance in the metal microstructure layer 31 . From the viewpoint of enhancing the intensity of the emission peak caused by molecular vibration and increasing the infrared emissivity in the wavelength range of the emission peak, the wavelength of the emission peak caused by localized surface plasmon resonance is changed to that caused by molecular vibration. It is preferable to set it so as to be close to the wavelength of the emission peak. For example, the wavelength of the emission peak caused by localized surface plasmon resonance is preferably within ±3 μm of the wavelength of the emission peak caused by molecular vibration, more preferably within ±2 μm, and more preferably within ±1 μm. A range is even more preferred.

The organic polymer material contained in the dielectric layer 32 is not particularly limited as long as it has molecular bonds that can absorb heat and excite vibration. The organic polymer material is preferably a heat-resistant organic polymer material having heat resistance to withstand the heat when heated by the heating layer 4 . The term "heat resistance" as used herein means that the heat-resistant organic polymer material is heated at least in the range of 100 to 200°C, preferably in the range of 200 to 300°C. more preferably in the range of 300 to 400° C., still more preferably in the range of 400 to 500° C., the molecular bonds that can excite vibration are at least 60% or more compared to before heating, preferably means the property of remaining 70% or more, more preferably 80% or more, still more preferably 90% or more.

The heat-resistant organic polymer material is not particularly limited as long as it has heat resistance, absorbs heat, excites vibration, and has a molecular bond capable of emitting infrared rays caused by the vibration. However, it preferably contains one or more selected from the group consisting of polyimide resins, epoxy resins, thermosetting elastomer resins, melamine resins, fluororesins and urea resins. The heat-resistant organic polymer material is one or two selected from the group consisting of polyimide resins, epoxy resins and thermosetting elastomer resins, from the viewpoint of enhancing localized surface plasmon resonance and enhancing molecular vibration. More preferably, it contains more than one species.

The thickness of the dielectric layer 32 containing the organic polymer material is not particularly limited, but from the viewpoint of increasing the radiation intensity of the infrared rays emitted by exciting the vibration of the molecular bonds contained in the dielectric layer 32 , is preferably 50 nm or more, more preferably 100 nm or more, and even more preferably 200 nm or more. The film thickness of the dielectric layer 32 is preferably 600 nm or less, more preferably 500 nm or less, from the viewpoint of further enhancing localized surface plasmon resonance and further enhancing molecular vibration of molecular bonds contained in the dielectric layer 32. More preferably, 400 nm or less is even more preferable.

The metal layer 33 enhances the localized surface plasmon resonance generated in the metal microstructure layer 31 by stacking the metal microstructure layer 31 with the dielectric layer 32 interposed therebetween. The metal layer 33 contains at least a metal component and is formed as a conductive layer. In this embodiment, the metal layer 33 is formed as a continuous film below the dielectric layer 32, as shown in FIG. The metal layer 33 is not particularly limited as long as it can enhance localized surface plasmon resonance, and can be formed by a known film formation method such as resistance heating vapor deposition, sputtering, and electron beam vapor deposition.

The thickness of the metal layer 33 is not particularly limited as long as it can enhance the localized surface plasmon resonance. The metal layer 33 is preferably configured so that the infrared reflectance is higher than the infrared transmittance, from the viewpoint of reflecting infrared rays and suppressing the transmission of infrared rays. The film thickness of the metal layer 33 is, for example, preferably 100 nm or more, more preferably 150 nm or more, and even more preferably 200 nm or more, from the viewpoint of reflecting infrared rays and suppressing transmission of infrared rays. From the viewpoint of uniformity, the thickness of the metal layer 33 is preferably 1000 nm or less, more preferably 600 nm or less, and even more preferably 400 nm or less.

The material of the metal layer 33 is not particularly limited as long as it can enhance the localized surface plasmon resonance. The metal layer 33 is preferably made of, for example, a metal having a high reflectance to infrared rays. , aluminum (Al), osmium (Os), rhodium (Rh), and ruthenium (Ru). Metal layer 33 may be made of indium tin oxide (ITO) containing metal components such as tin (Sn) and indium (In). From the viewpoint of surface chemical stability, the metal layer 33 more preferably contains one or more selected from the group consisting of gold (Au) and silver (Ag). Gold (Au) is most preferable from the viewpoint of surface chemical stability.

The heating layer 4 is a layer that heats the infrared emitter 3 . In the infrared light source 1, the heating layer 4 is provided between the substrate 2 and the infrared emitter 3, and is provided close to the infrared emitter 3 without interposing the substrate 2, so that the infrared emitter of the substrate is Compared to the case where the heating layer is provided on the side opposite to the side where the heating layer is provided, thermal diffusion to the substrate is suppressed, and infrared rays can be stably radiated in a short time from the start of heating. In this embodiment, the heating layer 4 is formed as a continuous film between the substrate 2 and the infrared emitters 3 . The heating layer 4 is not particularly limited, and can be formed by a known film forming method such as resistance heating vapor deposition, sputtering, electron beam vapor deposition.

The heating layer 4 is not particularly limited as long as it can heat the infrared emitter 3, and can be formed using a known resistor that generates heat when energized, for example. Examples of usable resistors include nichrome alloys, kanthal alloys, tungsten, and platinum.

The thickness of the heating layer 4 is not particularly limited as long as it can heat the infrared emitter 3 . From the viewpoint of increasing the heating capacity, the thickness of the heating layer 4 is, for example, preferably 100 nm or more, more preferably 150 nm or more, and even more preferably 200 nm or more. From the viewpoint of uniformity, the thickness of the heating layer 4 is preferably 1000 nm or less, more preferably 600 nm or less, and even more preferably 400 nm or less.

As shown in FIG. 2, the infrared light source 1 includes, in addition to the substrate 2, the infrared emitter 3, and the heating layer 4 described above, a heat conduction suppressing layer 5 provided between the substrate 2 and the heating layer 4, and a heating layer. It further comprises an insulating layer 6 provided between the layer 4 and the infrared emitter 3 . That is, the infrared light source 1 is provided with the heat conduction suppressing layer 5 on the substrate 2, the heating layer 4 on the heat conducting suppressing layer 5, the insulating layer 6 on the heating layer 4, and the insulating layer 6 on the heating layer 4. An infrared emitter 3 is provided on top of the layer 6 . However, the infrared light source 1 is provided with an adhesive layer A2 such as chromium (Cr) or titanium (Ti) between the layers for the purpose of ensuring adhesion between the layers, as shown in the figure. (in the illustrated example, it is provided only between the infrared emitter 3 and the insulating layer 6).

The heat conduction suppressing layer 5 is a layer that suppresses heat conduction between the substrate 2 and the heating layer 4 . In the infrared light source 1, the thermal conduction suppression layer 5 suppresses heat conduction between the substrate 2 and the heating layer 4, thereby suppressing the diffusion of heat to the infrared emitter 3 to the substrate 2. can be done. As a result, infrared radiation can be stably emitted from the infrared emitter 3 in a short time from the start of heating of the heating layer 4 .

The heat conduction suppressing layer 5 is not particularly limited as long as it can suppress heat conduction between the substrate 2 and the heating layer 4, and can be formed of a known low thermal conductivity material. As the low thermal conductivity material, the thermal conductivity at 20° C. is 0.8 W/m·K or less, preferably 0.6 W/m·K or less, more preferably 0.4 W/m·K or less, still more preferably A material of 0.3 W/m·K or less can be used. A heat-resistant organic polymer material is exemplified as such a low thermal conductivity material, and the heat conduction suppressing layer 5 preferably contains the heat-resistant organic polymer material. Examples of heat-resistant organic polymer materials include one or more selected from the group consisting of polyimide resins, epoxy resins, thermosetting elastomer resins, melamine resins, fluororesins and urea resins.

The thickness of the heat conduction suppressing layer 5 is not particularly limited as long as it can suppress heat conduction between the substrate 2 and the heating layer 4 . The film thickness of the heat conduction suppressing layer 5 is preferably 200 nm or more, more preferably 400 nm or more, and even more preferably 500 nm or more, from the viewpoint of further suppressing heat conduction. From the viewpoint of uniformity of the heat conduction suppression layer 5, the thickness of the heat conduction suppression layer 5 is preferably 5000 nm or less, more preferably 3000 nm or less, and even more preferably 1000 nm or less.

The insulating layer 6 is a layer that electrically insulates between the heating layer 4 and the infrared emitter 3 . In the infrared light source 1, the insulating layer 6 electrically insulates the heating layer 4 from the infrared emitter 3, thereby suppressing current flow between the heating layer 4 and the infrared emitter 3. Fluctuations in infrared radiation emitted by the infrared emitter 3 can be suppressed. In particular, when a structure that causes localized surface plasmon resonance is employed in the infrared emitter 3 as in the present embodiment, current flow between the heating layer 4 and the infrared emitter 3 is suppressed. By doing so, attenuation of localized surface plasmon resonance can be suppressed.

The insulating layer 6 is not particularly limited as long as it can electrically insulate between the heating layer 4 and the infrared emitter 3, and can be formed of a known high resistance material. As the high resistance material, a material having a volume resistivity of 10 ⁶ Ω·cm or more, preferably 10 ⁹ Ω·cm or more, more preferably 10 ¹¹ Ω·cm or more, and even more preferably 10 ¹³ Ω·cm or more is used. be able to. The insulating layer 6 is preferably made of a material that ensures insulation between the heating layer 4 and the infrared emitters 3 and does not inhibit heat conduction from the heating layer 4 to the infrared emitters 3 . From such a point of view, the insulating layer 6 is preferably formed of a material having a higher thermal conductivity than, for example, the heat conduction suppressing layer 5 described above, and more specifically, contains an inorganic (electrical) insulating material. is preferred. Examples of inorganic insulating materials include silicon oxide (such as _SiO2 ), silicon nitride (such as _Si3N4 ), aluminum oxide (such as _Al2O3 ), hafnium oxide (such _{as HfO2} ), _and zirconium oxide (such as _ZrO2 ). ) and titanium oxide (TiO ₂ etc.).

The insulating layer 6 is not particularly limited as long as it can electrically insulate between the heating layer 4 and the infrared emitter 3 . From the viewpoint of insulation, the thickness of the insulating layer 6 is preferably 10 nm or more, more preferably 30 nm or more, and even more preferably 50 nm or more. From the viewpoint of thermal conductivity, the thickness of the insulating layer 6 is preferably 200 nm or less, more preferably 150 nm or less, and even more preferably 100 nm or less.

REFERENCE SIGNS LIST 1 infrared light source 2 substrate 3 infrared emitter 31 metal microstructure layer 31a metal microstructure 32 dielectric layer 33 metal layer 4 heating layer 5 heat conduction suppression layer 6 insulation layer A1, A2 adhesion layer L infrared radiation M gas detector M1 operation Part M2 Display Part N Gas Sensor N1 Housing N2 Reflective Structure N3 Infrared Detector N4 Circuit Part V Internal Space

Claims (6)

a substrate;
an infrared light emitter provided on the substrate and absorbing heat to emit infrared light;
An infrared light source comprising a heating layer provided between the substrate and the infrared emitter and heating the infrared emitter,
The infrared light source is
a heat conduction suppression layer provided between the substrate and the heating layer for suppressing heat conduction between the substrate and the heating layer;
an insulating layer provided between the heating layer and the infrared emitter and electrically insulating between the heating layer and the infrared emitter ;
The heat conduction suppressing layer contains a heat-resistant organic polymer material,
infrared light source. The infrared light emitter is
a metal microstructure layer capable of absorbing heat to produce localized surface plasmon resonance;
a dielectric layer provided under the metal microstructure layer;
a metal layer provided under the dielectric layer so as to sandwich the dielectric layer between the metal microstructure layer;
An infrared light source according to claim 1. The heat conduction suppressing layer has a film thickness of 500 nm or more and 5000 nm or less.
3. An infrared light source according to claim 1 or 2 . wherein the insulating layer comprises an inorganic insulating material;
An infrared light source according to any one of claims 1 to 3 . The insulating layer has a thickness of 50 nm or more and 100 nm or less,
An infrared light source according to any one of claims 1-4 . A gas sensor comprising the infrared light source according to any one of claims 1 to 5 .

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