JP5030059B2 - Sensor substrate and composite sensor using the same - Google Patents

Description

  The present invention relates to a sensor substrate using a piezoelectric element that can be used for substance adsorption detection. In particular, the present invention relates to a composite sensor using a quartz crystal microbalance and an optical waveguide.

As a conventional substance adsorption sensor, as disclosed in Patent Document 1, a small amount of NO ₂ gas is utilized by utilizing the fact that the oscillation frequency of the crystal resonator is lowered according to NO ₂ gas adsorbed on the gas sensitive film. There is known a sensor capable of detecting

  In addition, as disclosed in Patent Document 2, a method is known in which substance adsorption is detected by absorbing an evanescent field generated by guiding light through an optical waveguide by the adsorbed substance and attenuating the guided light. ing.

  Further, as disclosed in Patent Document 3, a metal thin film is deposited on an optical waveguide, and when the surface plasmon is excited on the metal thin film by the guided light, the guided light is attenuated. In connection with this, there is known a method for detecting substance adsorption by measuring the emitted light using the change in the surface plasmon excitation condition.

  Further, Patent Document 4 has a structure in which a clad made of a low refractive index medium and a core made of a high refractive index medium are laminated on a crystal resonator, and an optical waveguide layer serving as an optical waveguide for guiding light is provided. A composite sensor characterized by the above has been proposed. Detection of the target substance by utilizing both the change in the emitted light due to the change in the propagation loss and the change in the oscillation characteristics of the crystal unit as the target substance is adsorbed on the core surface of the optical waveguide. There is an advantage that can be easily identified.

Patent Document 4 discloses a sensor characterized in that a metal thin film is provided on an optical waveguide. A prism arrangement method is also disclosed. Further, Patent Document 4 discloses a sensor including a metal colloid layer formed on a quartz resonator. The arrangement method of the prism is also disclosed in the same manner. That is, in the conventional method, the incident prism to the core layer functioning as the optical waveguide is disposed so as to be in contact with the core layer as in Patent Document 4 (for example, FIG. 1). It is customary to arrange the same in the prism coupling method to a well-known optical waveguide.
JP 7-43285 A Japanese Patent Laid-Open No. 9-61346 JP 2001-108612 A International Publication WO2006 / 038367

  However, in the conventional sensor disclosed in Patent Document 1, a small amount of gas adsorbed on a gas-sensitive thin film by utilizing the nature of a crystal resonator, the so-called QCM (Quartz Crystal Microbalance) principle. However, there is a problem that it is not possible to directly know the optical properties of the substance to be detected and the sensitive thin film after adsorption.

  Further, the conventional sensors disclosed in Patent Documents 2 and 3 have a problem in that it is impossible to directly know how much mass of the detection target substance is adsorbed on the element and causes a change in emitted light. It was.

  Therefore, in view of the above problems, the present invention utilizes a piezoelectric element, and a sensor substrate capable of accurately and simultaneously detecting the amount of change in adsorbed mass of a substance to be detected and the amount of change in optical characteristics associated therewith, and a substance using the same An object is to provide a composite sensor for adsorption.

  On the other hand, in the composite sensor described in Patent Document 4, since the arrangement of the prisms for entering and exiting the light into the optical waveguide layer has a conventional structure, the operation of bringing the prisms into contact with the core layer is extremely skillful. In addition, it was time consuming. In addition, since the process of patterning the sensing layer and exposing the core layer is necessary, the cost tends to increase for manufacturing the sensor substrate portion.

  Furthermore, since it was difficult to form an optical waveguide layer on a quartz crystal substrate used as a QCM (hereinafter referred to as a QCM substrate as appropriate) with high accuracy, optical coupling between the prism and the core layer was realized. It was difficult to do. In addition, if a sensor substrate with poor flatness is used, variations in optical coupling efficiency are likely to occur between sensor substrates, making it difficult to perform stable measurement.

  For this reason, when measuring by exchanging a plurality of sensor substrates, there is a particularly inconvenient and inconvenient place. Such a usage method is a general usage method in a QCM sensor, and is also a usage mode desired in a composite sensor with an optical waveguide sensor.

  That is, the present invention has been made as a result of diligent efforts to solve the above-described problems in manufacturing and use of the sensor substrate, and specifically uses the composite sensor described in Patent Document 4. In accordance with the form, it is improved and put into practical use at a low cost. In particular, the present invention has been achieved after diligent efforts to realize a form that is easy to use by separating the composite sensor substrate from the measurement apparatus.

  In order to solve the above problems, a sensor substrate according to the present invention is a sensor substrate in which a clad layer, a core layer, and a sensing layer are laminated in this order on at least one side of a substrate made of a piezoelectric material having electrodes formed on both sides. Thus, the electrode acts as an electrode of the vibrator, and the core layer constitutes an optical waveguide that is a main waveguide region.

  In this sensor substrate, the piezoelectric material is preferably quartz. The core layer is preferably a resin material. Moreover, it is preferable that the sensing layer is a resin material containing cobalt chloride.

  The core layer and / or the cladding layer is preferably a fluorine-containing resin. Moreover, it is preferable that the water absorption rate of the resin material of the sensing layer is larger than the water absorption rate of the resin material of the core layer. A metal thin film layer is preferably formed between the core layer and the sensing layer.

  In order to solve the above-described problem, the composite sensor according to the present invention has an incident prism on the surface of the sensor substrate on which the sensing layer is formed so that the optical path of the optical waveguide crosses the facing portion of the electrode of the vibrator. And an emission prism is disposed, and the sensor substrate is supported by pressing of the two prisms and the base material, and the surface of the base material is insulative except for a contact point with an electrode lead portion of the sensor substrate. It is a composite sensor of an optical waveguide characterized by being covered with a material and a crystal resonator used as a QCM.

  It is preferable that a base material provided with an opening or a counterbore at least at a portion facing the electrode is disposed on a surface opposite to the surface on which the sensing layer is formed.

  This composite sensor is a surface of the sensor substrate on which the sensing layer is formed, and introduces a gas containing a substance to be detected into the sensor substrate between the incident prism and the output prism. It is preferable that a gas introduction cell for this purpose is provided in close contact with the sensing layer.

  Further, it is preferable that the gas introduction cell uses silicon rubber at a close contact portion with the sensing layer. The gas introduction cell preferably has an exhaust port for exhausting the gas. The gas introduction cell preferably has a double pipe structure.

  In the present invention, the sensing layer is formed on the entire surface of the sensor substrate like the optical waveguide layer. By doing so, it is not necessary to pattern the sensing layer, and the number of processes is greatly reduced, so that a sensor substrate can be manufactured at low cost. On the other hand, if the thickness of the sensing layer is too thick, there is a possibility that coupling will not occur even if the prism is pressed. Therefore, in the present invention, the operation is actually confirmed by forming the sensing layer as a thin film.

  On the other hand, in order to form the sensing layer as a thin film, it is necessary to control the film thickness with high accuracy. However, by using a sensor substrate structure that combines QCM as in the present application, the thickness of the sensing layer can be easily specified by performing QCM measurement during or after the sensing layer is formed. It is.

  In the composite sensor of the present invention, the gas introduction cell is provided in close contact with the sensing layer between the incident prism and the emission prism on the surface of the sensor substrate where the sensing layer is formed. Gas is introduced only into the waveguide portion so that the gas does not reach the coupling portion with the prism.

  In the sensor substrate and the composite sensor using the same according to the present invention, the change in the emitted light due to the change in the propagation loss and the oscillation characteristics of the quartz crystal resonator due to the adsorption of the substance to be detected on the core surface of the optical waveguide. It is possible to easily detect and identify the substance to be detected by utilizing the fact that both change. For example, when substances other than the detection target substance are adsorbed at the same time, it is impossible to identify only by the oscillation characteristics of the quartz crystal resonator in the sensor, but it is possible to simultaneously measure the refractive index by changing the optical characteristics. You can see that different media are adsorbed.

  Further, by providing a metal thin film on the core, surface plasmons can be resonantly excited in the metal thin film by evanescent waves generated in the vicinity of the core by guided light. When surface plasmons are excited, the guided light attenuates, and the excitation conditions change sensitively due to the adsorption of the substance, so measuring the optical characteristics with higher sensitivity by measuring the emitted light, Oscillation characteristics can be observed. Furthermore, by depositing a sensitive material whose optical characteristics change due to substance adsorption on the surface of the metal thin film, it is possible to detect a trace amount of substance better.

  Furthermore, by utilizing the characteristics of metal colloid that generates local plasmons (LP) when irradiated with light, it is possible to measure changes in transmitted light or scattered light accompanying substance adsorption.

  Furthermore, since a sensitive material is deposited on the uppermost layer so that the optical characteristics change due to the adsorption of the substance to be detected, and thereby the propagation loss is greatly changed, a trace substance can be detected well.

  The sensor substrate of the present invention and the composite sensor using the same are piezoelectric elements (quartz vibrators or surface acoustic wave elements) having an optical waveguide, and can detect the adsorption mass of a substance by the piezoelectric element and accompany the substance adsorption. From the change of the emitted light, the optical characteristics of the adsorbed substance or the thin film for detection after the substance adsorption can be observed with one element.

  Compared to the case where a piezoelectric element and an element for measuring optical characteristics are separately manufactured and observed, the above method can accurately detect the amount of change in adsorption mass and the amount of change in optical characteristic. In particular, when the adsorbed substance is decomposed by light irradiation, or when adsorption or desorption is promoted, a large error will occur if it is produced separately. It is possible to measure in detail the photodecomposition and the adsorption phenomenon by light.

  In addition, by observing the relationship between the adsorption mass and optical properties of several detection target substances, it is possible to identify substances with different masses that give the same change in optical properties per number of adsorbed molecules. It is.

  Furthermore, since the core layer is made of a resin material, the elastic modulus is smaller than that of the inorganic material, so that it is easy to press the prism for entering / exiting light to / from the optical waveguide. In the case of a material having a high elastic modulus, since deformation due to pressing is small, it is usually necessary to perform prism coupling in combination with matching oil or the like. However, when used as a sensor of a substance like the present invention, sensing If there is a liquid such as matching oil in the vicinity of the layer, contamination to the sensing layer is likely to occur, so the reliability as a sensor is lacking.

  Since the sensing layer is a resin material containing cobalt chloride, a color reaction due to moisture absorption or the like occurs, so that not only the mass but also a change in color, that is, a change in the propagation light intensity of the optical waveguide can be sensed simultaneously.

  Since the core layer is made of a fluorine-containing resin, the water absorption is smaller than that of a normal resin, so that background noise generated by the core layer can be reduced. It is particularly effective in detecting water-soluble substances and moisture. In addition, because the clad layer and core layer are made of fluorine-containing resin, the dielectric constant is lower than that of ordinary resin, so that attenuation of the QCM signal at high frequency can be suppressed, and highly sensitive mass change detection. Is possible. In particular, fluorinated polyimide is preferable for the core layer and the cladding layer. Fluorinated polyimide has a lower water absorption than ordinary resins. In addition, since fluorinated polyimide has high workability, when it is used as a waveguide, it becomes easy to form a multilayer of the waveguide because of easy lamination.

  By setting the water absorption rate of the resin material of the sensing layer to be larger than the water absorption rate of the resin material of the core layer, detection with a high S / N becomes possible. It is particularly effective in detecting water-soluble substances and moisture.

  Since the metal thin film layer is formed between the core layer and the sensing layer, the effect of surface plasmon resonance can be used, and the change in the refractive index of the sensing layer can be detected with high sensitivity.

  By using the counter electrode portion of the QCM as an opening, the offset of the oscillation frequency can be reduced, and highly accurate mass measurement can be performed. Further, it has been found that the prism can be easily pressed in this way. The reason is assumed to be due to minute deformation of the sensor substrate itself.

  According to the composite sensor of the present invention, the gas introduction cell is provided in close contact with the sensing layer between the incident prism and the emission prism on the surface of the sensor substrate where the sensing layer is formed. Therefore, the gas can be introduced only into the waveguide portion, and the gas can be prevented from reaching the coupling portion with the prism. When the gas reaches the prism, the incident light and the emitted light can be prevented from being physically affected by the gas, and the adsorbed substance can be detected with high accuracy.

  Hereinafter, preferred embodiments of the sensor substrate of the present invention will be described with reference to the drawings. Note that, in each of these embodiments, the same portions are denoted by the same reference numerals, and the description of the common parts will be omitted as much as possible. Although a case where a quartz substrate is used as the piezoelectric material will be described, the scope of the present invention is not limited to this. For example, a surface acoustic wave element can be used as the piezoelectric material. As the sensing layer, a layer having a property of causing a change in absorption spectrum due to absorption or adsorption of the substance to be detected is employed.

  The present invention is a sensor substrate in which a clad layer, a core layer, and a sensing layer are laminated in this order on at least one side of a substrate made of a piezoelectric material having electrodes formed on both sides, and the electrode functions as an electrode of a vibrator. , A sensor substrate characterized in that the core layer constitutes an optical waveguide serving as a main waveguide region, wherein the oscillation characteristics of the crystal resonator and the light emitted from the waveguide are observed simultaneously or alternately. is there.

(Embodiment 1)
FIG. 1 shows an arrangement example of the sensor substrate 10 in the present embodiment. A crystal resonator 11 including a crystal (substrate) 1 and a pair of crystal oscillation electrodes 2 and 3, and the crystal oscillation electrode 3 are shown. An optical waveguide layer 12 comprising a cladding part 4 made of a low refractive index medium, a core part 5 made of a high refractive index medium, and an adsorbed substance detection thin film (sensing layer) 7 placed thereon; Consists of. The sensing layer 7 becomes a gas adsorption part.

In the sensor substrate 10, the sensing layer 7 is formed of an organic functional material such as a resin in which cobalt chloride CoCl ₂ is dispersed. As the resin, it is preferable to use polyvinyl alcohol PVA. That is, as the sensing layer 7, it is preferable to use polyvinyl alcohol PVA in which cobalt chloride CoCl ₂ is dispersed.

Cobalt chloride CoCl ₂ has a chromism phenomenon in which the color tone changes from blue to red when moisture is absorbed to become a hydrate, and the color tone returns from red to blue when moisture is lost. By forming a sensing layer 7 made of polyvinyl alcohol PVA in which cobalt chloride CoCl ₂ having this chromism phenomenon is dispersed on the core of the optical waveguide, and utilizing the light absorption characteristics due to moisture absorption of the sensing layer 7, the change of the waveguide characteristics Can be observed.

FIG. 2 shows the light absorption characteristics of the cobalt chloride CoCl ₂ dispersed polyvinyl alcohol PVA thin film. The horizontal axis indicates the wavelength of light (Wavelength [nm]), and the vertical axis indicates the absorbance (Absorbance [arb.units]. The initial state is a state dried at 120 degrees in the atmosphere, and the expired state is about 100% humidity. The absorbance changes reversibly in a dry state and a moisture absorption state when the light wavelength is from 550 nm to 750 nm, and light having a wavelength of 632.8 nm is particularly preferable as a wavelength incident on the optical waveguide because the absorbance change is large. .

The sensing layer 7 is produced by, for example, a dip coating method on an optical waveguide substrate formed on the crystal resonator 11. Specifically, the optical waveguide substrate is dipped in a cobalt chloride CoCl ₂ dispersed polyvinyl alcohol PVA thin film solution and pulled up. The thickness of the sensing layer 7 can be determined by the concentration of the cobalt chloride CoCl ₂ -dispersed polyvinyl alcohol PVA thin film solution. The film thickness is preferably 0.3 μm or less, for example, 30 nm, 63 nm, 100 nm, 143 nm, 216.4 nm, or the like.

For example, the CoCl ₂ / PVA concentration is 3 g / l (liter) with respect to water, or 4 g / l. When both are 4 g / l, a sensing layer with a film thickness of 30 nm is obtained assuming a density of 1 g / cm ³ . Further, when the CoCl ₂ concentration is 5 g / l and the PVA concentration is 20 g / l, a sensing layer having a film thickness of 143.6 nm is obtained on the assumption that the density is 1 g / cm ³ . Further, when the CoCl ₂ concentration is 10 g / l and the PVA concentration is 30 g / l, a sensing layer having a film thickness of 216.4 nm is obtained on the assumption that the density is 1 g / cm ³ .

As the sensing layer is thicker and the CoCl ₂ concentration is higher, the absorbance increases. However, in the waveguide type sensor of the present invention, this does not directly increase the sensitivity of the sensor. That is, in the sensor of the configuration of the present invention, the change in the refractive index of the sensing layer or the change in absorbance is felt by the evanescent wave component of the light guided through the adjacent core layer. The intensity of this evanescent wave component is When the refractive index is selected to be smaller than the refractive index of the core layer, it attenuates exponentially as the distance from the interface between the core layer and the sensing layer increases. That is, when the sensing layer is thin, the evanescent wave has an intensity from the entire sensing layer to the outside of the sensing surface, so that the sensitivity increases as the sensing layer becomes thicker. However, if the sensing layer becomes thicker to some extent and the evanescent wave no longer reaches the surface of the sensing layer, the sensitivity will increase because the evanescent wave will not overlap even if the sensing layer is thick. I can't hope. Rather, the apparent sensitivity may increase or decrease gradually due to the diffusion of the analyte in the sensing layer, which will be described later, which is not preferable depending on the purpose of use of the sensor. The penetration depth of the evanescent wave from the interface between the core layer and the sensing layer to the sensing layer varies depending on the thickness, refractive index, and wavelength of the cladding layer, the core layer, and the sensing layer. From this viewpoint, the optimum thickness of the sensing layer is preferably 1/10 to 2 times the wavelength. Further, it is preferable to set the wavelength to 1/5 to 1 time. More preferably, the wavelength is 1/3 to 1/2 times the wavelength.

  When the refractive index of the sensing layer is selected to be larger than the refractive index of the core layer, the sensing layer becomes a waveguide region together with the core layer, and the main total reflection interface on the sensing layer surface side is the sensing layer and the core layer. It becomes the sensing layer surface, not the interface. When the sensing layer is thin, only a slight perturbation is added to the waveguide conditions of the entire waveguide, but when the sensing layer is thick, the sensing layer becomes the main waveguide region. In this case, when the sensing layer absorbs the analyte, the waveguide conditions of the entire waveguide constituting the sensor greatly fluctuate, and there is a possibility that it cannot be distinguished from the change in absorbance of the sensing layer. For this reason, it is preferable that the core layer is the main waveguide region. In order to make the core layer the main waveguide region, the sensing layer may be selected such that the refractive index of the sensing layer is smaller than the refractive index of the core layer, or the thickness of the sensing layer may be reduced. In this respect, the thickness of the sensing layer is preferably 1/1000 to 1/10 of the thickness of the core layer. Further, it is 1/500 to 1/50.

  Note that if the sensing layer absorbs the sample and the input / output conditions at the prism fluctuate, it is not suitable for input / output at the prism. Is preferred.

Moreover, it is considered that the response speed with respect to the moisture absorption change is better as the sensing layer is thinner and the CoCl ₂ concentration is higher. That is, if the thickness of the sensing layer is too large, the specimen adsorbed on the surface of the sensing layer diffuses inside the sensing layer and is close enough to be detected by the guided light until it approaches the core layer. Since it is not detected as a change in the guided light signal, there may be a time lag corresponding to the diffusion time. On the other hand, when the environmental gas concentration on the surface of the sensing layer is decreased, the sample diffused inside the sensing layer as described above is desorbed along with the desorption of surface adsorbed molecules (analyte). Since the concentration of the analyte in the vicinity of the core layer decreases and the opposite change of the guided light signal occurs, there is a possibility that a time lag may occur here.

  Further, the optimum film thickness is set to 50 nm to 500 nm in consideration of repeated use or considering strength. More preferably, the thickness of the sensing layer is 100 nm to 300 nm.

The sensing layer 7 can also be produced by spin-coating a cobalt chloride CoCl ₂ -dispersed polyvinyl alcohol PVA thin film solution on the optical waveguide layer 12 by spin coating.

  The sensing layer may be made of any material that adsorbs a substance to be detected and whose optical characteristics (complex dielectric constant) change accordingly. For example, any material that is formed from an organic functional substance such as porphyrin and that adsorbs a substance to be detected and changes its optical characteristics (complex dielectric constant) accordingly can be used. The sensing layer can be made of any material that is formed of an organic functional substance such as a dye exhibiting solvatochromism, and that adsorbs a substance to be detected and changes its optical characteristics (complex dielectric constant). Further, for example, any material that is formed from an organic functional substance such as lychart dye and that adsorbs a substance to be detected and changes its optical characteristics (complex dielectric constant) accordingly can be used.

  The cladding portion 4 of the low refractive index medium used for the optical waveguide layer 12 enables optical waveguide in the core portion 5. The core portion 5 is made of a medium having a refractive index higher than that of the cladding portion 4 and the outside that exposes the element. The low refractive index and the high refractive index described here are relative values obtained by comparing the refractive indexes of the cladding portion 4 and the core portion 5. For example, the refractive index of the cladding part 4 is 1.547 for TE light having a measurement wavelength of 632.8 nm. Further, it is 1.538 for TM light of the same wavelength. The refractive index of the core part 5 is 1.552 to 1.597 for TE light having the same wavelength. Further, it is 1.542 to 1.597 for TM light.

  The core part 5 and the clad part 4 are made of a fluorine-containing resin. In particular, fluorinated polyimide is preferred. Fluorinated polyimide has a lower water absorption than ordinary resins. In addition, since fluorinated polyimide has high workability, when it is used as a waveguide, it becomes easy to form a multilayer of the waveguide because of easy lamination. Of course, the material of the clad part 4 and the core part 5 is not limited to fluorinated polyimide as long as it enables optical waveguide, but is preferably a visible transparent resin. The film thickness of the cladding part 4 is preferably constant in the range of 5 μm to 20 μm. Moreover, it is preferable that the film thickness of the core part 5 is also constant within the range of 5 μm to 20 μm.

  The optical waveguide layer 12 is formed by forming a fluorinated polyimide on one surface of the crystal resonator 11 by a spin coating method. Specifically, the clad fluorinated polyimide is spin-coated on the crystal oscillation electrode 3 and then heated to form the clad portion 4, and the core fluorinated polyimide is spin-coated on the clad portion 4. Then, the core part 5 is formed by heating. The film thickness can be controlled by changing the spin coating speed, that is, the spin rotation speed.

  When light is incident on the core 5, the light is guided while being totally reflected inside the core. At this time, the change of the emitted light from the core part 5 by adsorption | suction of to-be-detected substance is observed. Furthermore, the crystal unit 11 can detect the amount of adsorption of the substance to be adsorbed.

As described above, the crystal unit 11 is composed of the crystal (substrate) 1 and the pair of crystal oscillation electrodes 2 and 3, and is gas sensitive by utilizing the Quartz Crystal Microbalance (QCM) phenomenon. A small amount of gas adsorbed on the thin film can be detected. Specifically, the property that the oscillation frequency changes according to the mass of the substance to be detected is used. This oscillation frequency is sometimes referred to as the QCM frequency. For example, the QCM frequency decreases with respect to N ₂ gas containing moisture. For dry N ₂ gas, the QCM frequency is restored to the initial state.

  The composite sensor using the sensor substrate of the above embodiment measures the oscillation characteristics of the crystal resonator 11 and the intensity of light guided using the optical waveguide layer 12 as an optical waveguide. That is, by utilizing the fact that the change in the emitted light due to the change in the propagation loss and the change in the oscillation characteristics of the crystal resonator 11 are accompanied by the adsorption of the substance to be detected on the core portion 5 of the optical waveguide layer. Thus, detection and identification of a substance to be detected can be easily performed. For example, when substances other than the detection target substance are adsorbed at the same time, it cannot be identified only by the oscillation characteristics of the crystal resonator 11 on the sensor substrate 10, but due to changes in the optical characteristics of the optical waveguide layer 12. It is possible to know that different media are adsorbed by measuring the refractive index simultaneously.

  Furthermore, a sensitive material such as the sensing layer 7 that changes the optical characteristics due to adsorption of the substance to be detected on the surface of the core portion 5 positioned at the uppermost layer of the optical waveguide layer 12 and thereby greatly changes the propagation loss. Since they are deposited, the detection of trace substances can be performed well.

  Further, the adsorption mass of the substance can be detected by the oscillation frequency characteristic of the crystal resonator, and the optical characteristic of the adsorbed substance or the sensing layer 7 after the substance adsorption can be observed with one element from the change of the emitted light accompanying the substance adsorption.

  Compared to the case where the quartz vibrator and the element for measuring the optical characteristics are separately manufactured and observed, the above-described composite sensor can accurately detect the amount of change in adsorption mass and the amount of change in optical characteristics. In particular, when the adsorbed substance is decomposed by light irradiation, or when adsorption or desorption is promoted, a large error will occur if the QCM and the optical waveguide are manufactured separately. By doing so, it is possible to measure in detail such photodecomposition and adsorption phenomenon by light.

  Furthermore, by observing the relationship between the adsorption mass and optical properties of several substances to be detected, it is possible to identify substances with different masses that give the same change in optical properties per number of adsorbed molecules. It is.

(Embodiment 2)
In the second embodiment, a metal thin film 6 having an appropriate thickness is installed between the core portion 5 and the sensing layer 7 as shown in FIG. In this case, with respect to a certain wavelength and incident angle determined by the film thickness and dielectric constant of the core part 5 and the metal thin film 6, the film thickness and dielectric constant of the sensing layer 7, and the dielectric constant of the outside world, Surface plasmons can be excited on the surface of the metal thin film by the generated evanescent wave. At this time, the transmitted light is attenuated at a wavelength for exciting the surface plasmon. By theoretically calculating the attenuation of the transmitted light, the dielectric constant or film thickness of the sensing layer 7 after adsorption of the substance to be detected is obtained, and the state of oscillation of the crystal resonator is detected. In this case, the sensing layer and the substance to be detected are not necessarily light-absorbing.

  Of course, since the sensing layer 7 whose optical characteristics change due to substance adsorption is deposited on the surface of the metal thin film 6 also in the second embodiment, it is possible to detect a trace amount of substance better.

(Embodiment 3)
In recent years, a sensor using a local plasmon (LP) generated when a metal colloid having a diameter of about several tens of nanometers is irradiated with light has been proposed. This is based on the fact that when a substance is adsorbed on the metal colloid surface, the resonance wavelength, light absorption intensity or light scattering intensity of LP changes depending on the refractive index and film thickness of the substance.

  In this embodiment, this metal colloid is deposited on a quartz resonator, and the optical change and mass change associated with substance adsorption are combined by measuring the resonance wavelength of LP and the oscillation frequency change of the quartz resonator simultaneously. taking measurement. FIG. 4 shows a structural example. A gold (Au) colloid 17 as a metal colloid layer is deposited on a crystal resonator 11 in which the crystal 1 is sandwiched between a pair of electrodes 2 and 3. A substance to be detected is adsorbed on the gold colloid 17, the mass is changed by a quartz oscillator, and the resonance wavelength (absorption peak wavelength) of LP in the gold colloid 17 and the refractive index of the adsorbed substance are measured by measuring transmitted light or scattered light. Observe. At this time, if the electrodes 2 and 3 are transparent, the transmitted light of the gold colloid thin film on the electrodes can be observed. If the electrodes 2 and 3 are not transparent, the transmitted light of the gold colloid thin film in the vicinity of the electrodes is measured.

  According to said structure, the change of the transmitted light accompanying substance adsorption | suction can be measured using the characteristic of the gold colloid 17 which generate | occur | produces a local plasmon (LP) when light is irradiated. At this time, scattered light may be used for light detection. A surface acoustic wave element may be used as the mass detection means.

(Embodiment 4)
FIG. 5 is an explanatory view including the prism arrangement of the composite sensor 30 using the sensor substrate described in the first to third embodiments. Although illustrated with respect to the sensor substrate of the first embodiment, in the second and third embodiments, a composite sensor can be realized with the same configuration.

  The composite sensor 30 includes a crystal resonator 11 including a crystal 1 and a pair of crystal oscillation electrodes 2 and 3, a cladding portion 4 including a low refractive index medium on the crystal oscillation electrode 3, and a high height disposed thereon. Light is incident on the optical waveguide layer 12 composed of the core portion 5 made of a refractive index medium, the sensing layer 7 acting as a gas adsorbing portion, which is a thin film for detecting an adsorbed material disposed thereon, and the core portion 5. A light incident prism 8 serving as a light incident means, a light emitting prism 9 serving as a light emitting means for extracting light from the core 5, and a base material 31 disposed on a surface opposite to the prisms 8 and 9. In addition, a lead (not shown) from the counter electrode of the QCM is formed on the base material and an insulating layer 32 for electrically insulating.

  The composite sensor 30 has a structure in contact with the sensing layer 7 instead of the conventional structure in which the prism is in direct contact with the core layer. For this reason, it is not necessary to remove a part of the sensing layer 7 and directly contact the prism with the core layer as in the prior art, so that it can be easily manufactured and can be easily coupled to and detached from the prism.

  In addition, the base material 31 is provided with an opening or a punch at a portion facing the crystal electrode 2. A plan view of the substrate 31 is shown in FIG. 29 described later. A rectangular opening 31 a of 13 mm × 10 mm is provided at a portion facing the crystal electrode 2. As a result, the composite sensor 30 has a free space on the back surface of the crystal unit 11 and can oscillate stably.

(Material adsorption detection system)
Next, a substance adsorption detection system using the composite sensor 30 of the present invention will be described with reference to FIG. FIG. 6 is a diagram illustrating a specific example of the substance adsorption detection system 40 using the composite sensor 30. In the substance adsorption detection system, it is required to perform measurement while replacing a plurality of composite sensors. The substance adsorption detection system 40 using the composite sensor 30 can also perform measurement while replacing the composite sensor 30. In this case, the composite sensor 30 is sandwiched between the incident light prism 8 and the outgoing light prism 9 and the base material 31 and attached to the sensor holding portion.

  In the substance adsorption detection system 40, laser light having a wavelength λ = 633 nm is incident on a light incident prism 8 of the composite sensor 30 from a helium-neon laser (He-Ne Lather) 41. After this laser beam is emitted from the laser 41, a TM mode or a TE mode is set by selectively attaching a polarizing plate. For example, the laser beam in the TM mode is incident obliquely on the light incident prism 8 through a chopper (not shown).

  The laser light incident on the optical waveguide layer 12 of the composite sensor 30 from the light incident prism 8 propagates while totally reflecting the core portion 5 and is emitted from the light emitting prism 9. The emitted light emitted from the light emitting prism 9 is detected by a photodetector (PD) 42. The detection signal of the PD 42 is supplied to the multimeter 43 and read. The detection signal read by the multimeter 43 is processed by a personal computer (PC) 44 and displayed on the monitor 44a as a detection value or a change in characteristics.

  The crystal oscillator (QCM oscillator) 11 is connected to an oscillation controller 45 for supplying power to the crystal oscillation electrodes 2 and 3 and measuring the oscillation frequency. The oscillation controller 45 is connected to the PC 44 and sends a signal indicating the oscillation frequency value to the PC 44.

  The PC 44 displays the emitted light intensity of the laser beam transmitted from the optical waveguide layer 12 via the PD 42 and the multimeter 43 on the monitor 44 a and also transmits the QCM transmitted from the QCM transmitter 11 via the oscillation controller 45. Displays the frequency.

The sensing layer 7 of the composite sensor 30 is supplied with dry N ₂ gas flowing through the pipe 52 or wet N ₂ gas bubbled in the solution to be measured from the jet port 52a. These gases pass through a silica gel container 49 or solution container 50 from N ₂ gas from the N ₂ gas cylinder 46 is flow adjusted by a float meter 47 through the valve 48, flows through the pipe 52 through the valve 51 It is obtained by coming. The N ₂ gas whose flow rate is adjusted from the float meter 47 is adjusted through a valve 48 and passed through a silica gel container 49 to obtain dry N ₂ gas. The valve 51 is opened and dry N ₂ gas is supplied to the sensing layer 7 from the jet port 52a through the pipe 52. On the other hand, the N ₂ gas whose flow rate is adjusted from the float meter 47 is bubbled into the solution container 50 by adjusting the valve 48 to obtain, for example, N ₂ gas containing moisture. The valve 51 is opened, and N ₂ gas containing moisture is supplied to the sensing layer 7 from the jet port 52a through the pipe 52.

Thus material suction detecting system 40, while switching dried N ₂ gas or solution to be measured through silica gel container 49, the N ₂ gas valves 48 and 51 that was bubbled in, for example, pure water flowing in the pipe 52, The emission light intensity guided through the optical waveguide layer 12 and the oscillation frequency of the quartz crystal resonator 11 at the same time are alternately or alternately measured from the jet nozzle 52a on the sensing layer 7 of the composite sensor 30. Are processed and displayed on the monitor 44a.

  More specifically, the sensing layer 7 of the composite sensor 30 is exposed to the substance to be detected, and a change in the oscillation frequency of the crystal resonator 11 is observed by the oscillation controller 45 and the PC 44 during that time. For example, at the same time, laser light is incident on the core 5 from the light source 41 through the light incident prism 8 to guide the optical waveguide layer 12. The incident angle of light is an angle within a range in which light is totally reflected in the core portion 5 and light is guided. When the laser light is guided through the core portion 5, an evanescent field is generated in the vicinity of the core surface outside the core (this distance is determined by the dielectric constant and the incident angle of the interface medium). If a light-absorbing substance is present in the region where the evanescent field is generated, the light guided through the core portion 5 is attenuated by the absorption of the evanescent field. The sensing layer 7 exists in a region where the evanescent wave oozes, and when the light absorption characteristic of the sensing layer 7 that has adsorbed the substance to be detected changes before the adsorption, the absorption of the evanescent wave by the sensing layer 7 changes. Therefore, the state of attenuation of light emitted from the core portion 5 through the light emitting prism 9 also changes. The emitted light is measured by the photodetector 42. Then, the measurement result is processed by the multimeter 43 and the PC 44 and displayed on the monitor 44a.

  If the substance to be detected itself is light-absorbing, the sensing layer 7 may not be light-absorbing. In addition, if the refractive index of the sensing layer 7 is larger than the refractive index of the core part 5, light leaks from the core part 5, but this is used to change the refractive index due to adsorption of the substance to be detected. Thus, a substance capable of changing the light confinement and the propagation loss in the core portion 5 to change the emitted light may be used for the sensing layer 7.

  Further, the incident laser light is white light or monochromatic light including a wavelength that is absorbed by the sensing layer 7 or the substance to be detected, or whose propagation loss changes due to adsorption of the substance to be detected and the emitted light intensity changes. When the substance to be detected is adsorbed on the element and thus the surface of the sensing layer 7, the spectrum or intensity of the light emitted from the core unit 5 changes as described above. In this system, the wavelength of the incident laser light is 633 nm, but the wavelength is not limited to this.

  At this time, the mass of the composite sensor substrate element increases by the amount of adsorption of the substance to be detected. Since the crystal oscillator 11 has a property (QCM) in which the inherent oscillation frequency changes according to the mass of the deposit adhered to the surface thereof, the frequency decreases as the amount of gas to be detected increases. . That is, the frequency characteristic of the crystal unit 11 changes in proportion to the mass of the detected gas that has been adsorbed.

FIG. 7 shows a specific example of the humidity detection characteristic obtained by the substance adsorption detection system 40. FIG. 7A shows the first measurement and FIG. 7B shows the second measurement. The horizontal axis represents time, the left vertical axis represents a change in oscillation frequency (Frequency shift [Hz]: FS), and the right vertical axis represents light intensity (Light intensity [V]: LI). By switching the valves 48 and 51, a humidity of 15% dry _{N 2} gas, a humidity of 70% of the wet _{N 2} gas was blown from the alternating ejection port 52a to the sensing layer 7 of the composite sensor 30.

In the first measurement shown in FIG. 7A, first, dry N ₂ gas was sprayed for 15 minutes. The outgoing light intensity Light detected by the PD 42 after being guided through the optical waveguide layer 12 in this initial dry section is about 0.11 [V] when 10 minutes have elapsed. Further, the oscillation frequency shift FS of the crystal unit 11 was about 300 [Hz] during this initial drying period. When wet N ₂ gas was blown onto the sensing layer 7 after 15 minutes had elapsed, the oscillation frequency shift FS decreased and the emitted light intensity LI increased. At about 10 minutes after the wet period, the oscillation frequency shift FS was −1600 Hz, and the emitted light intensity LI was 0.145 [V]. At this time (25 minutes in total), the wet period was switched to the dry period. That is, when dry N ₂ gas was sprayed onto the sensing layer 7, the oscillation frequency shift FS increased and returned to the initial dry zone state. Further, the emitted light intensity LI decreased and returned to the initial dry section state.

In the second measurement shown in FIG. 7 (B), the time to switch from the dry section, which is the initial state, to the wet section was 6 minutes later, and wet N ₂ gas was sprayed onto the sensing layer 7 for 10 minutes. Then, it returned to the initial state at the time of 16 minutes in total, that is, the drying section. Changes in the oscillation frequency shift FS and the emitted light intensity LI in each section are substantially the same as in the first measurement. Of course, when wet N ₂ gas with a humidity of 70% was introduced, the oscillation frequency shift FS decreased and the emitted light intensity LI increased. Then, when dry N ₂ gas having a humidity of 15% was introduced, the initial state was restored.

  Since these emitted light characteristics and frequency characteristics show specific values according to the amount and type of adsorption of the substance to be detected, changes in adsorption mass and light transmission characteristics observed for some detection target substances in advance. By comparing the relationship, the detected substance can be detected and identified. Specifically, adsorption mass and light transmission characteristics data observed for some detection target substances in advance are stored in a table memory, and the relationship of changes in each measured characteristic is referred to the table memory. The detected substance can be detected and identified by comparing with known data and the target substance name.

  As described above, it is possible to detect and identify the substance to be detected from the amount of adsorption of the substance to be detected, that is, the amount of change in the emitted light corresponding to the frequency change of the crystal resonator.

  In the composite sensor according to the present invention, the adsorption mass of the substance can be detected by the oscillation frequency characteristic of the quartz crystal resonator 11 with one sensor substrate, and the change amount of the emitted light characteristic with respect to the adsorption mass can be observed by the optical waveguide layer 12. Thereby, since it is not necessary to use two sensors side by side like the past, it is possible to pinpoint and accurately detect one point (one point) to be detected. For example, when the core layer is patterned by a known method to form a plurality of optical waveguides on the same substrate and a plurality of sensor substrate configurations of the present invention are formed on the same substrate, multipoint sensing is performed. Is possible and effective.

  In the above embodiments, the sensor may be in gas or liquid. In addition, this invention is not limited to said each embodiment, It can change in the range which does not deviate from the meaning of this invention. The shape of the sensing layer (adsorbed substance detection thin film) 7 is not particularly limited, and various substances can be detected by changing the material.

  By the way, in the substance adsorption detection system 40 using the composite sensor 30 of the fourth embodiment, the dry gas is blown from the outlet 52 a of the pipe 52 to the sensing layer 7 between the light incident prism 8 and the light emitting prism 9. It was. However, the gas is adsorbed to the prism 8 and the prism 9 due to the gas flow rate or the distance between the prisms being narrow, and the adsorbed moisture may affect the coupling of the prism to the sensing layer 7.

(Embodiment 5)
Therefore, a composite sensor of Embodiment 5 different from the composite sensor 30 was produced. FIG. 8 is a schematic configuration diagram of the composite sensor 60. In the composite sensor 60, a gas introduction cell 61 is provided on the surface of the sensor substrate on which the sensing layer 7 is formed. The gas introduction cell 61 is disposed in close contact with the sensing layer 7 in order to introduce a gas containing a substance to be detected into the sensor substrate. In particular, the gas introduction cell 61 is in close contact with the sensing layer 7 between the light incidence prism 8 and the light emission prism 9 that are arranged at a distance of, for example, 12 mm.

  The gas introduction cell 61 is made of, for example, polypropylene and has a cylindrical shape inside. The gas containing the substance to be detected or the dry gas supplied from the pipe 52 connected to the gas incident end 61c is supplied from the gas emission end 61d to the sensing layer. 7 is sprayed. The gas introduction cell 61 is provided with an exhaust port 61 b for exhausting the gas returned from the sensing layer 7. Further, the gas introduction cell 61 has a close contact portion 61a on the gas emission end 61d side.

FIG. 9 is a view showing the appearance of the gas introduction cell 61. The gas introduction cell 61 has a height of 102 mm, for example. The gas introduction cell contact portion 61a has a rectangular shape having a side r ₁ wider than the inner diameter r ₀ of the cylindrical gas introduction cell 61 main body. The cylindrical main body of the gas introduction cell 61 is a double-structured cylinder with an inner diameter of about 2.5 mm and an outer shape of about 3.00 mm. For the contact surface 61d, for example, a silicon rubber with a thickness of 0.5 mm having a refractive index lower than that of the core 5 or the like is used. Further, the original thickness of the gas introduction cell contact portion 61a is also 0.5 mm. Therefore, the distance from the sensing surface of the spraying part in the close contact part is 1 mm. The pressure for pressing the silicon rubber against the sensing layer 7 needs to be adjusted appropriately so as not to affect the refractive index change, the pressing pressure of the prism against the sensing layer 7, and the like. Of course, the silicone rubber is preferably transparent.

  By using the gas introduction cell 61 described above, the composite sensor 60 can introduce the gas only into the waveguide portion and prevent the gas from reaching the coupling portion with the prism.

(Embodiment 6)
Next, the composite sensor of Embodiment 6 will be described. FIG. 10 is a schematic configuration diagram of the composite sensor 70. This composite sensor 70 also has a gas introduction cell 71 on the surface of the sensor substrate on which the sensing layer 7 is formed. The gas introduction cell 71 is disposed in close contact with the sensing layer 7 in order to introduce a gas containing a substance to be detected into the sensor substrate. In particular, the gas introduction cell 71 is in close contact with the sensing layer 7 between the light incidence prism 8 and the light emission prism 9 which are arranged at a distance of, for example, 12 mm.

  The gas introduction cell 71 used in the composite sensor 70 has a double-pipe structure, and has a structure in which two gas introduction cells 61 of the fifth embodiment are stacked. Of course, the silicone rubber described above is used for the contact portion with the sensing layer 7.

  By using the gas introduction cell 71 having the double pipe structure described above, the composite sensor 70 can efficiently introduce the gas containing the substance to be detected or the dry gas into the sensing layer 7, and the prism and The gas can be prevented from reaching the coupling portion.

(Substance adsorption detection system using embodiment 5)
Next, a substance adsorption detection system using the composite sensor 60 will be described with reference to FIG. FIG. 11 is a diagram illustrating a specific example of the substance adsorption detection system 80 using the composite sensor 60.

  The substance adsorption detection system 80 is different from the substance adsorption detection system 40 shown in FIG. 6 in that a composite sensor 60 using a gas introduction cell 61 is provided instead of the composite sensor 30.

The sensing layer 7 of the composite sensor 60 will flow through a pipe 52, the N ₂ gas was bubbled into dry N ₂ gas or solution to be measured gas coupling portion between the prism is prevented from reaching the gas introducing cells 61 Supplied from the contact portion 61a.

Thus material suction detecting system 80, while switching dried N ₂ gas or solution to be measured through silica gel container 49, the N ₂ gas valves 48 and 51 that was bubbled in, for example, pure water flowing in the pipe 52, It is introduced into the sensing layer 7 of the composite sensor 60 from the close contact portion 61a of the gas introduction cell 61, and the intensity of the emitted light guided through the optical waveguide layer 12 and the oscillation frequency of the crystal resonator 11 are measured simultaneously or alternately. The measurement results are processed by the PC 44 and displayed on the monitor 44a.

  As described above, the substance adsorption system 80 having the composite sensor 60 having the gas introduction cell 61 is shown with reference to FIG. 11, but the composite sensor 70 having the gas introduction cell 71 having the double inter-structure shown in FIG. Needless to say, the substance adsorption system can be a specific example (hereinafter referred to as a modified example).

  Next, a specific example of the humidity detection characteristic obtained by the substance adsorption detection system 80 or the modified system will be described. FIG. 12 is a humidity detection characteristic diagram obtained by the substance adsorption detection system 80 having the composite sensor 60 provided with the gas introduction cell 61. The horizontal axis represents time, the right vertical axis represents oscillation frequency shift (Frequency shift [Hz]: FS), and the left vertical axis represents light intensity (Light intensity [V]: LI).

The sensing layer 7 was formed as a thin film by spin-coating cobalt chloride CoCl ₂ -dispersed polyvinyl alcohol PVA on the core portion 5 of the optical waveguide layer 12. Concentrations at that time are 30 g / l of cobalt chloride CoCl _{2 and} 10 g / l of polyvinyl alcohol PVA with respect to 1 l (liter) of pure water.

After the initial state, the valves 48 and 51 were switched, and dry N ₂ gas and wet N ₂ gas were alternately introduced from the gas introduction cell 61 to the sensing layer 7 of the composite sensor 60. Specifically, after introducing dry N ₂ gas for 5 minutes in the initial state, wet N ₂ gas is introduced for 10 minutes, then dry N ₂ gas is introduced for 10 minutes, and then wet N ₂ gas is introduced for 5 minutes. Dry N ₂ gas was introduced for an additional 10 minutes.

  In the initial state, the oscillation frequency shift FS was 0 Hz, and the emitted light intensity LI was 0.01V. In the next wet section, the oscillation frequency shift FS greatly shifted to −2000 Hz. In addition, the light intensity LI changed greatly to 0.05V. Thereafter, a large change in oscillation frequency (QCM frequency) and light intensity was observed with repeated drying and wet. The recovery at the time of switching was also good.

  As described above, the substance adsorption detection system 80 having the composite sensor 60 including the gas introduction cell 61 can observe the change in the QCM frequency) and the light intensity when the dry gas and the wet gas are alternately introduced into the sensing layer 7. It was. Therefore, in the substance adsorption detection system 80, adsorption mass and light transmission characteristics data observed for some detection target substances in advance are stored in a table memory, and changes in the measured characteristics are measured. The detected substance can be detected and identified by comparing the relationship with the known data and the target substance name with reference to the table memory.

  Hereinafter, some examples of the embodiments 1 to 6 and the substance adsorption detection system using them will be described.

<Formation of optical waveguide on crystal resonator>
Example 1
FIG. 13 is a plan view and a cross-sectional view of the quartz substrate 104 with electrodes. As shown in FIG. 13, a quartz substrate (AT cut made by MAXTEK) with electrodes 102 and 103 in which a titanium and gold thin film is patterned into a predetermined shape on both sides of a quartz substrate 101 having a thickness of 0.333 mm and a diameter of 25.4 mm as a quartz substrate. ) 104 was prepared.

  Next, the clad part of the optical waveguide is formed using the spin coater 105 shown in FIG. As shown in FIG. 15, a fluorine-containing polyimide resin (OPI-N3305: trade name, manufactured by Hitachi Chemical Co., Ltd.) is used as the lower clad layer on the entire upper surface of the crystal substrate 104 with electrodes. The quartz crystal substrate 101 was set so as to be in the center, and a material solution film was formed by spin coating at a rotation speed of 1800 rpm × 30 seconds. Thereafter, the solvent is evaporated by heating at 100 ° C. for 30 minutes and then at 200 ° C. for 30 minutes using a dryer, and then the resin is cured by heating at 370 ° C. for 60 minutes, so that the center of the quartz substrate with electrodes is A lower clad layer was formed so as to have a thickness of 5 μm.

  On this lower clad, a fluorine-containing polyimide resin (OPI-N3405: trade name, manufactured by Hitachi Chemical Co., Ltd.) is used as a core layer, as shown in FIG. 15, and the substrate chuck 105a of the spin coater 105 becomes the center of the substrate. In this manner, the quartz substrate 101 having the lower clad formed thereon was set and spin-coated at a rotation speed of 1060 rpm × 30 seconds to form a material solution film. Thereafter, the solvent is evaporated by heating at 100 ° C. for 30 minutes and then at 200 ° C. for 30 minutes using a dryer, and then the resin is cured by heating at 370 ° C. for 60 minutes, so that the center of the quartz substrate with electrodes is The core layer was formed so as to have a thickness of 10 μm.

(Example 2)
The substrate used, the material of the waveguide layer, and the curing conditions were the same as in Example 1, and only the film thickness was changed by changing the number of spin rotations.

  A lower clad layer was spin-coated on the entire upper surface of the quartz substrate 101 at a rotation speed of 900 rpm × 30 seconds to form a material solution film, and then the resin was cured using a drier to form a lower clad layer having a thickness of 10 μm. .

  On the lower clad, the core layer was spin-coated at a rotation speed of 1060 rpm × 30 seconds to form a material solution film, and then the resin was cured using a drier to form a 10 μm thick core layer.

(Example 3)
The substrate used, the material of the waveguide layer, and the curing conditions were the same as in Example 1, and only the film thickness was changed by changing the number of spin rotations.

  A lower clad layer was spin-coated on the entire upper surface of the quartz substrate 101 at a rotation speed of 500 rpm × 30 seconds to form a material solution film, and then the resin was cured using a dryer to form a lower clad layer having a thickness of 15 μm. .

  On the lower clad, the core layer was spin-coated at a rotation speed of 1060 rpm × 30 seconds to form a material solution film, and then the resin was cured using a dryer to form a core layer having a thickness of 10 μm.

Example 4
The substrate used, the material of the waveguide layer, and the curing conditions were the same as in Example 1, and only the film thickness was changed by changing the number of spin rotations.

  A lower clad layer was spin-coated on the entire upper surface of the quartz substrate 101 at a rotation speed of 900 rpm × 30 seconds to form a material solution film, and then the resin was cured using a drier to form a lower clad layer having a thickness of 10 μm. .

  On the lower clad, the core layer was spin-coated at a rotation speed of 680 rpm × 30 seconds to form a material solution film, and then the resin was cured using a dryer to form a core layer having a thickness of 15 μm.

  FIG. 16 shows the film thicknesses of the lower cladding layer and the core layer manufactured under these conditions. The horizontal axis indicates the R direction of the quartz substrate, and 0 indicates one end of the quartz substrate. The measurement was performed using a stylus type film thickness meter DEKTAKst3 (manufactured by ULVAC).

  From FIG. 16, it can be seen that the film thicknesses of the lower cladding layer and the core layer of Example 4 are 10 μm and 15 μm in the vicinity of 10000 μm to 15000 μm (center portion). Further, it can be seen that both end portions of 5000 nm or less and 17000 nm or more differ by about 5 to 15 μm from the center portion.

(Example 5)
The substrate used, the material of the waveguide layer, and the curing conditions were the same as in Example 1, and only the film thickness was changed by changing the number of spin rotations.

  A lower clad was spin-coated on the entire upper surface of the quartz substrate at a rotation speed of 1800 rpm × 30 seconds to form a material solution film, and then the resin was cured using a drier to form a lower clad layer having a thickness of 5 μm.

  On the lower clad, the core was spin-coated at a rotation speed of 500 rpm × 30 seconds to form a material solution film, and then the resin was cured using a dryer to form a core layer having a thickness of 20 μm.

  FIG. 17 shows the film thicknesses of the lower cladding layer and the core layer manufactured under these conditions. The horizontal axis indicates the R direction of the quartz substrate, and 0 indicates one end of the quartz substrate. The measurement was performed using a stylus type film thickness meter DEKTAKst3 (manufactured by ULVAC).

  From FIG. 17, it can be seen that the film thicknesses of the lower cladding layer and the core layer of Example 5 are 5 μm and 15 μm in the vicinity of 10000 μm to 15000 μm (center portion). Further, it can be seen that both end portions of 6000 nm or less and 19000 nm or more differ by about 10 to 15 μm from the central portion.

(Example 6)
A quartz substrate with electrodes (ATTE made by MAXTEK) prepared by patterning a titanium and gold thin film into a predetermined shape on a quartz substrate having a thickness of 0.333 mm and a diameter of 25.4 mm as a quartz substrate was prepared.

  A fluorine-containing polyimide resin (OPI-N3305: trade name, manufactured by Hitachi Chemical Co., Ltd.) as a lower clad on the entire top surface of the electrode-attached crystal substrate having a diameter of 25.5 mm that can accommodate a crystal substrate with an electrode as shown in FIG. A crystal substrate 104 is set as shown in FIG. 19 in a spin jig 110 having a counterbore hole (depth of counterbore 0.350 mm) 111 and having a diameter of 125 mm, and a substrate chuck 105a of a spin coater 105 is shown in FIG. Was set at the center of the spin jig 110 and spin-coated at a rotation speed of 900 rpm × 30 seconds to form a material solution film. Then, after evaporating the solvent to some extent by heating at 100 ° C. for 30 minutes using a dryer, the crystal substrate 104 with the electrode coated with the lower clad is taken out from the spin jig, and then heated at 200 ° C. for 30 minutes. Then, the solvent was further evaporated and the resin was cured by heating at 370 ° C. for 60 minutes to form a lower cladding layer having a thickness of 10 μm.

  A spin having a counterbore 111 on which a quartz substrate 104 with electrodes as shown in FIG. 10 can be accommodated on this lower clad with a fluorine-containing polyimide resin (OPI-N3405: trade name, manufactured by Hitachi Chemical Co., Ltd.) as a core layer. As shown in FIG. 19, the crystal substrate 104 with electrodes is set on the jig 110, and the substrate chuck 105a of the spin coater 105 is set at the center of the jig as shown in FIG. 20, and the rotational speed is 680 rpm × 30. A material solution film was formed by spin coating in seconds. Then, after evaporating the solvent to some extent by heating at 100 ° C. for 30 minutes using a dryer, the electrode-attached crystal substrate 104 coated with the lower clad is taken out from the spin jig 110 and then heated at 200 ° C. for 30 minutes. Thus, the solvent was further evaporated, and subsequently the resin was cured by heating at 370 ° C. for 60 minutes to form a core layer having a thickness of 15 μm.

  FIG. 21 shows the film thicknesses of the lower cladding layer and the core layer manufactured under these conditions. The horizontal axis indicates the R direction of the quartz substrate, and 0 indicates one end of the quartz substrate. The measurement was performed using a stylus type film thickness meter DEKTAKst3 (manufactured by ULVAC).

  From FIG. 21, it can be seen that the film thicknesses of the lower cladding layer and the core layer of Example 5 are substantially the same as 10 μm and 10 μm at both end portions and the central portion.

(Example 7)
The substrate used, the material of the waveguide layer, the use of the spin jig, and the curing conditions were the same as in Example 6, and the film thickness was changed by changing the spin rotation speed.

  A lower clad was spin-coated on the entire upper surface of the quartz substrate 101 at a rotation speed of 1800 rpm × 30 seconds to form a material solution film, and then the resin was cured using a dryer to form a lower clad layer having a thickness of 5 μm.

  On this lower clad layer, a core is spin-coated at a rotation speed of 1060 rpm × 30 seconds to form a material solution film, and then the resin is cured using a dryer to form a core layer having a thickness of 10 μm as a core layer. Formed.

(Example 8)
The substrate used, the material of the waveguide layer, the use of the spin jig, and the curing conditions were the same as in Example 6. Only the film thickness was changed by changing the number of spin rotations.

  A lower clad was spin-coated on the entire upper surface of the quartz substrate 101 at a rotation speed of 680 rpm × 30 seconds to form a material solution film, and then the resin was cured using a dryer to form a lower clad layer having a thickness of 15 μm.

  On this lower clad layer, a core was spin-coated at a rotation speed of 1060 rpm × 30 seconds to form a material solution film, and then the resin was cured using a dryer to form a core layer having a thickness of 10 μm.

Example 9
The substrate used, the material of the waveguide layer, the use of the spin jig, and the curing conditions were the same as in Example 6. Only the film thickness was changed by changing the number of spin rotations.

  A lower clad was spin-coated on the entire upper surface of the quartz substrate 101 at a rotation speed of 1800 rpm × 30 seconds to form a material solution film, and then the resin was cured using a dryer to form a lower clad layer having a thickness of 5 μm.

  On the lower clad layer, a core was spin-coated at a rotation speed of 500 rpm × 30 seconds to form a material solution film, and then the resin was cured using a drier to form a core layer having a thickness of 20 μm.

<Formation of sensing layer>
(Example 10)
A sensing layer was formed on the optical waveguide substrate formed on the quartz resonator as in Examples 1 to 9 as follows. A cobalt chloride (CoCl ₂ ) -dispersed polyvinyl alcohol (PVA: degree of polymerization 500, Kanto Chemical 32283-02) thin film was prepared by dip coating. The concentration of CoCl ₂ -dispersed PVA was 3 g / l with respect to pure water, and the ratio of CoCl ₂ and PVA was 1: 1.

(Example 11)
A cobalt chloride-dispersed PVA thin film was formed in the same manner as in Example 10 except that the concentration of PVA was 4 g / l on the optical waveguide substrate formed on the crystal resonator as in Examples 1 to 9. A film was formed as a sensing layer.

(Example 12)
A sensing layer was formed on the optical waveguide substrate formed on the quartz resonator as in Examples 1 to 9 as follows. It was prepared by dip coating a lychart dye (272442 manufactured by Sigma-Aldrich) dispersed polyvinyl alcohol (PVA: polymerization degree 500, Kanto Chemical 32283-02) thin film. The concentration of the lychet dye-dispersed PVA was 4 g / l with respect to pure water, and the ratio of the lychet dye and PVA was 1: 1.

<Measurement of sensing layer thickness>
(Example 13)
The thickness of the sensing layer formed as in Examples 10 to 12 was evaluated from the measured value of the change in the frequency of the QCM as follows. In the evaluation, the Sauerbrey equation (1) was used.

  The thickness of the sensing layer in Example 10 was calculated to be 63 nm because the QCM frequency before forming the sensing layer was 477769 Hz and the QCM frequency after forming the sensing layer was 4771413 Hz.

  The thickness of the sensing layer in Example 11 was calculated to be 108 nm because the QCM frequency before forming the sensing layer was 4771769 Hz, and the QCM frequency after forming the sensing layer was 477159 Hz.

  The thickness of the sensing layer in Example 12 was calculated to be 143 nm because the QCM frequency before forming the sensing layer was 477769 Hz and the QCM frequency after forming the sensing layer was 4770957 Hz.

  Thus, it was shown that the film thickness of the sensing layer can be accurately identified by forming the sensing layer with a simple structure of the sensor substrate as in the present invention.

<Sensor measurement>
As the measurement sample, a sensing layer was produced as in Examples 10 to 12 on the QCM produced in Examples 1 to 9. The QCM of the measurement sample was sandwiched between two prisms 8 and 9 for incident light and outgoing light using a base material 31 as shown in FIG. 5 of an optical waveguide measuring device. The distance between the prisms, that is, the waveguide length was about 1 cm. As shown in FIG. 6, a He—Ne laser (λ = 633 nm) 41 was used as the light source.

  The laser light was changed to TM mode by a polarizing plate, passed through a chopper (about 737 Hz) and obliquely incident on the incident light prism. The incident angle was 30 degrees. The incident light propagates while totally reflecting the core portion 5 in the optical waveguide layer 12 on the QCM, and is emitted by another outgoing light prism 9. The emitted light intensity at this time was detected by the PD 42, and the GPIB output of the lock-in amplifier (NF 5610 B) was read by a multimeter (Advantest R6551 / EMC) 43. The QCM oscillator (quartz crystal) 11 is a RQCM manufactured by Maxtek. Aluminum foil electrodes 2 and 3 were provided between the electrically insulated substrate and the QCM, from which they were connected to the electrode portion of the RQCM holder 31 by means of an alligator clip and a copper wire, and measurement was performed.

N ₂ gas was used as the gas, and the flow rate was adjusted with the float meter 47. (Flow rate of the experiment is about 158.5ml / min) dry _{N 2} gas or measured in solution through silica gel container 49 (pure water) a _{N 2} gas was bubbled into the vessel 50 directly by switching the valves 49 and 51 Then, the sensing layer 7 on the optical waveguide layer 12 was sprayed, and the emitted light intensity LI and the oscillation frequency shift FS were measured simultaneously.

  In FIG. 22, each film thickness of the sensor substrate of Examples 1-9, a manufacturing method, etc. are shown collectively. In Example 1, the thickness of the core part is 10 μm, the thickness of the cladding part is 5 μm, the spin coating method of the core part and the cladding part is performed using the spin coater 105 shown in FIG. 14, and the sensing layer is further implemented. It is formed as distinguished in Examples 10, 11 and 12, indicating that the film thickness is 63 nm, 108 nm and 143 nm, respectively. Further, in Example 6, the core part has a thickness of 15 μm, the cladding part has a thickness of 10 μm, and the spin coating method of the core part and the cladding part is performed using the spin jig 110 having the counterbore shown in FIG. It represents that the sensing layer was formed as distinguished in Examples 10, 11 and 12, and the film thickness was 63 nm, 108 nm and 143 nm, respectively.

FIG. 23 shows humidity detection characteristics in Example 5 or 9 when the thickness of the sensing layer 7 is 63 nm. That is, the film thickness of the core part is 20 μm, the film thickness of the clad part is 5 μm, the sensing layer is 1: 1 by setting the concentration of the cobalt chloride CoCl ₂ -dispersed polyvinyl alcohol PVA thin film solution to 3 g / l, and by dip coating. This is the characteristic when The horizontal axis represents time, the left vertical axis represents the oscillation frequency change FS, and the right vertical axis represents the light intensity LI. By switching the valves 48 and 51 In the Adsorption detection system 40 shown in FIG. 6, a humidity of 15% dry _{N 2} gas, a humidity of 70% of the wet _{N 2} gas, integrated sensor from the ejection port 52a alternately 30 The sensing layer 7 was sprayed. When wet N ₂ gas is sprayed on the sensing layer 7, the oscillation frequency shift FS decreases due to moisture adsorption, but the emitted light intensity LI increases. This is because the light absorption of cobalt chloride CoCl ₂ in the sensing layer 7 decreases. When dry N ₂ gas is introduced into the sensing layer 7, the initial state is restored. That is, the change in the light absorption characteristics could be measured by the moisture absorption of the sensing layer 7 using the cobalt chloride CoCl ₂ dispersed polyvinyl alcohol PVA thin film.

  Since these emitted light characteristics LI and frequency characteristics FS show specific values according to the amount and type of adsorption of the substance to be detected, the adsorbed mass and light transmission characteristics of some of the substances to be detected previously observed. By comparing the change relationship, it is possible to detect and identify the substance to be detected. Specifically, adsorption mass and light transmission characteristics data observed for some detection target substances in advance are stored in a table memory, and the relationship of changes in each measured characteristic is referred to the table memory. The detected substance can be detected and identified by comparing with known data and the target substance name.

  However, in this case, an overshoot 121 was seen that returned after the light intensity LI changed significantly when switching from dry to wet and from wet to dry.

FIG. 24 shows humidity detection characteristics when the film thickness of the sensing layer 7 is 108 nm in Example 5 or 9. That is, the film thickness of the core part is 20 μm, the film thickness of the clad part is 5 μm, the sensing layer is 1: 1 with the concentration of the cobalt chloride CoCl ₂ -dispersed polyvinyl alcohol PVA thin film solution being 4 g / l, and formed by dip coating. This is the characteristic when The horizontal axis represents time, the left vertical axis represents the oscillation frequency change FS, and the right vertical axis represents the light intensity LI. By switching the valves 48 and 51 In the Adsorption detection system 40 shown in FIG. 6, a humidity of 15% dry _{N 2} gas, a humidity of 70% of the wet _{N 2} gas, integrated sensor from the ejection port 52a alternately 30 The sensing layer 7 was sprayed. When wet N ₂ gas is sprayed on the sensing layer 7, the oscillation frequency shift FS decreases due to moisture adsorption, but the emitted light intensity LI increases. This is because the light absorption of cobalt chloride CoCl ₂ in the sensing layer 7 decreases. When dry N ₂ gas is introduced into the sensing layer 7, the initial state is restored. That is, the change in the light absorption characteristics could be measured by the moisture absorption of the sensing layer 7 using the cobalt chloride CoCl ₂ dispersed polyvinyl alcohol PVA thin film.

  In this case, in the characteristic (122) when switching from dry to wet and from wet to dry, there was no overshoot that returned after the light intensity LI changed significantly.

Next, humidity detection characteristics when using a sensing layer (film thickness: 143 nm) dip-coated with lychar dye-dispersed PVA in Example 3 or Example 8 will be described with reference to FIGS. That is, the thickness of the core portion was 10 μm, the thickness of the cladding portion was 15 μm, and the sensing layer was formed by the dip coating method with the concentration of the lychart dye-dispersed polyvinyl alcohol PVA thin film solution being 4 g / l and 1: 1. Is a characteristic. In particular, FIG. 25 uses alcohol bubble gas. FIG. 26 shows acetone bubble gas. When a substance alcohol gas or acetone gas is sprayed on the sensing layer, the oscillation frequency shift FS decreases due to moisture adsorption, but the emitted light intensity LI increases. This is because the light absorption of the lychart dye in the sensing layer is reduced. When dry N ₂ gas is introduced into the sensing layer, it returns to the initial state. That is, the change in the light absorption characteristics could be measured by the moisture absorption of the sensing layer using the lychar dye-dispersed polyvinyl alcohol PVA thin film.

(Comparative Example 1)
Instead of forming the sensing layers of Examples 10 to 12 of the measurement samples used for the measurement of the humidity characteristics shown in FIGS. 23 to 27, experiments were similarly performed by forming a thin film of only PVA. FIG. 28 is a humidity absorption characteristic diagram thereof. The oscillation frequency decreased during the period in which the wet gas was introduced, and the dry gas was introduced to restore the initial state. However, the emitted light intensity LI did not have satisfactory characteristics.

<Comparison of sensor structures>
A specific example of the sensor structure of the present invention in the fourth embodiment described with reference to FIG. 5 will be described. As shown in the plan view of the base material 31 in FIG. 29, the base material 31 has a structure in which an opening 31 a is opened in the base material portion corresponding to the region of the crystal electrode 2 of the crystal resonator 11.

  The frequency of the QCM was measured with the sensor substrate sandwiched between the base material 31 and the incident / exit prisms 8 and 9. The results are shown in FIG. In the figure, it was described as “New optical waveguide holder”.

(Comparative Example 2)
The frequency of the QCM was measured in the same manner with the sensor substrate sandwiched between the entire flat substrate surface and the prism without providing holes in the substrate portion. The results are shown in FIG. In the figure, it was described as “front optical waveguide holder”.

(Comparative Example 3)
Using the standard QCM holder attached to the RQCM apparatus, the frequency of the QCM was measured in the same manner. The results are shown in FIG. In the figure, it is described as “RQCM holder”.

  As shown in FIG. 30, when the measurement was performed with a hole in the holder so that the back surface of the QCM became a space, the frequency measurement value of the QCM was a value close to the result of Comparative Example 3, which was the original measurement value. . Although a shift of about 1000 Hz remains, it is smaller than the shift of about 7000 Hz when the hole of Comparative Example 2 is not opened. Further, in the specific example in which the opening 31a is provided in the base material 31, the stability of the measurement data is improved as compared with the comparative example 2.

  As described above, it was found that the fourth embodiment is effective for forming the optical waveguide on the QCM and performing the simultaneous measurement of the mass change and the light intensity change with high reliability.

<Example of composite sensor using gas introduction cell>
Next, some examples of the composite sensors 60 and 70 using the gas introduction cells 61 and 71 shown in the embodiments 5 and 6 will be described.

(Example 14)
First, a quartz substrate (AT-cut made by MAXTEK) 104 with electrodes 102 and 103 prepared by patterning a thin film of titanium and gold into a predetermined shape on both sides of a quartz substrate 101 having a thickness of 0.333 mm and a diameter of 25.4 mm was prepared. .

  Next, the clad part of the optical waveguide is formed using the spin coater 105 shown in FIG. As shown in FIG. 15, a fluorine-containing polyimide resin (OPI-N3305: trade name, manufactured by Hitachi Chemical Co., Ltd.) is used as the lower clad layer on the entire upper surface of the crystal substrate 104 with electrodes. The quartz crystal substrate 101 was set so as to be in the center, and a material solution film was formed by spin coating at a rotation speed of 1800 rpm × 30 seconds. Thereafter, the solvent is evaporated by heating at 100 ° C. for 30 minutes and then at 200 ° C. for 30 minutes using a dryer, and then the resin is cured by heating at 370 ° C. for 60 minutes, so that the center of the quartz substrate with electrodes is A lower clad layer was formed so as to have a thickness of 5 μm.

  On this lower clad, a fluorine-containing polyimide resin (OPI-N3405: trade name, manufactured by Hitachi Chemical Co., Ltd.) is used as a core layer, as shown in FIG. 15, and the substrate chuck 105a of the spin coater 105 becomes the center of the substrate. In this manner, the quartz substrate 101 having the lower clad formed thereon was set and spin-coated at a rotation speed of 1060 rpm × 30 seconds to form a material solution film. Thereafter, the solvent is evaporated by heating at 100 ° C. for 30 minutes and then at 200 ° C. for 30 minutes using a dryer, and then the resin is cured by heating at 370 ° C. for 60 minutes, so that the center of the quartz substrate with electrodes is The core layer was formed so as to have a thickness of 10 μm.

On the optical waveguide substrate thus formed on the quartz resonator, a sensing layer was formed as follows. A cobalt chloride (CoCl ₂ ) -dispersed polyvinyl alcohol (PVA: degree of polymerization 500, Kanto Chemical 32283-02) thin film was prepared by dip coating. The concentration of CoCl ₂ -dispersed PVA was 5 g / l PVA and 20 g / l CoCl ₂ with respect to pure water. The ratio of PVA to CoCl ₂ is 1: 4. A sensing layer with a film thickness of 143.6 nm was obtained.

  Two prisms 8 and 9 for incident light and outgoing light were arranged on the sensing layer of the sensor substrate, and a gas introduction cell 61 was further placed between them to produce a specific example (Example 14) of the composite sensor 60.

  The composite sensor 60 of the fourteenth embodiment is set in the substance adsorption detection system 80 shown in FIG. 11, and the substance adsorption detection of the substance to be detected is performed. The incident angle (laser incident angle) of the laser beam to the composite sensor 60 is 28.33 degrees, and the polarization component is TM. In addition, the intensity of the incident laser beam is made smaller by using a light shielding plate (38.1%) than in the case of Example 15 described later. Therefore, the intensity of the emitted light is also smaller than the measurement of Example 15.

  FIG. 31 shows the humidity detection characteristics of Example 14. The horizontal axis represents time, the left vertical axis represents the oscillation frequency change FS, and the right vertical axis represents the light intensity LI that is the output of the photodetector PD. 32 to 35 show enlarged views in which the time axis is extended.

After the initial state, the valves 48 and 51 were switched, and dry N ₂ gas and wet N ₂ gas were alternately introduced from the gas introduction cell 61 to the sensing layer 7 of the composite sensor 60. First, as shown in FIG. 32, from 0 minutes to 30 minutes, the wet gas was repeated for 1 minute and the dry gas was 2 minutes. The gas flow rate was about 70 ml / min for wet gas and about 87 ml / min for dry gas. In the initial state, the oscillation frequency shift FS was 0 Hz, and the emitted light intensity LI was 0.1V. In the next wet section, the oscillation frequency shift FS greatly shifted to −1000 Hz. In addition, the light intensity LI changed greatly to 0.3V.

  Next, as shown in FIG. 33, the process was repeated for 40 minutes to 65 minutes with a wet gas of 2 minutes and a dry gas of 3 minutes. The gas flow rate was about 65 ml / min for wet gas and about 85 ml / min for dry gas. Even in this time zone, the oscillation frequency shift FS and the emitted light intensity LI alternately decreased and recovered repeatedly.

  Next, as shown in FIG. 34, from 80 minutes to 105 minutes, the process was repeated with 2 minutes of wet gas and 3 minutes of dry gas. The gas flow rate was about 120 ml / min for wet gas and about 150 ml / min for dry gas. Although the gas flow rate was changed significantly, the oscillation frequency shift FS and the emitted light intensity LI alternately decreased and recovered repeatedly during this time period.

  Next, as shown in FIG. 35, from 110 minutes to 150 minutes, the process was repeated with a wet gas of 10 minutes and a dry gas of 10 minutes. The gas flow rate was about 120 ml / min for wet gas and about 140 ml / min for dry gas. Although the gas introduction time was significantly changed, the oscillation frequency shift FS and the emitted light intensity LI alternately decreased and recovered repeatedly during this time period.

  Thus, in the substance adsorption detection system using Example 14, a relatively stable humidity detection characteristic was obtained although the base was changed.

(Example 15)
The substrate used for the optical waveguide layer 12, the material of the waveguide layer, the curing conditions, and the film thickness of the clad portion and the core portion were the same as those in Example 14. The film thickness of the sensing layer 7 was also set to a ratio of PVA to CoCl ₂ of 1: 4 and a film thickness of 143.6 nm. However, the intensity of the incident laser beam is not reduced by using a light shielding plate, as compared with the case of the above-described Example 14. Therefore, the emitted light intensity is also increased compared to the measurement of Example 14.

  The composite sensor 60 of the fifteenth embodiment is set in the substance adsorption detection system 80 shown in FIG. 11, and the substance adsorption detection of the substance to be detected is performed. The incident angle (laser incident angle) of the laser beam to the composite sensor 60 is 28.33 degrees, and the polarization component is TM.

  FIG. 36 shows the humidity detection characteristics of Example 15. The horizontal axis represents time, the left vertical axis represents the oscillation frequency change FS, and the right vertical axis represents the light intensity LI that is the output of the photodetector PD.

After the initial state, the valves 48 and 51 were switched, and dry N ₂ gas and wet N ₂ gas were alternately introduced from the gas introduction cell 61 to the sensing layer 7 of the composite sensor 60. Repeated for 5 minutes with wet gas and 5 minutes with dry gas. The gas flow rate was about 90 ml / min for wet gas and about 110 ml / min for dry gas. In the next wet section from the initial state, the oscillation frequency shift FS was greatly shifted, and the light intensity LI was also significantly changed and increased. And even if drying and wet were repeated, the oscillation frequency shift FS and the emitted light intensity LI alternately decreased and recovered repeatedly.

(Example 16)
The substrate used for the optical waveguide layer 12, the material of the waveguide layer, the curing conditions, and the film thickness of the cladding and core were the same as those in Example 15. The film thickness of the sensing layer 7 was also set to a ratio of PVA to CoCl ₂ of 1: 4 and a film thickness of 143.6 nm. Further, the intensity of the incident laser beam is not reduced without using a light shielding plate, as in the case of the fifteenth embodiment. However, in Example 16, compared with Example 15, the polarization component of the incident laser light is the TE component.

  The composite sensor 60 of Example 16 is set in the substance adsorption detection system 80 shown in FIG. 11, and the substance adsorption detection of the substance to be detected is performed. The incident angle (laser incident angle) of the laser beam to the composite sensor 60 is 28.33 degrees, and the polarization component is TE as described above.

  FIG. 37 shows the humidity detection characteristics of Example 16. The horizontal axis represents time, the left vertical axis represents the oscillation frequency change FS, and the right vertical axis represents the light intensity LI that is the output of the photodetector PD.

After the initial state, the valves 48 and 51 were switched, and dry N ₂ gas and wet N ₂ gas were alternately introduced from the gas introduction cell 61 to the sensing layer 7 of the composite sensor 60. Wet gas was introduced for 10 minutes and dry gas was introduced for 10 minutes. On the way, wet gas was introduced for 5 minutes and dry gas was introduced for 5 minutes. In other words, the gas introduction time was shortened. The gas flow rate was about 105 ml / min for wet gas and about 125 ml / min for dry gas. In the next wet section from the initial state, the oscillation frequency shift FS was greatly shifted, and the light intensity LI was also significantly changed and increased. And even if drying and wet were repeated, the oscillation frequency shift FS and the emitted light intensity LI alternately decreased and recovered repeatedly.

(Example 17)
The substrate used for the optical waveguide layer 12, the material of the waveguide layer, the curing conditions, and the film thickness of the cladding and core were the same as those in Example 15. The film thickness of the sensing layer 7 was also set to a ratio of PVA to CoCl ₂ of 1: 4 and a film thickness of 143.6 nm. Further, the intensity of the incident laser light is not reduced without using a light shielding plate, as in the case of the above-described embodiment 16. Further, in Example 17, similarly to Example 16, the polarization component of the incident laser light is used as the TE component. Example 17 differs from Example 16 in that the gas introduction time was switched at 5 minutes at the beginning and the wet gas introduction time was increased to 13 minutes later.

  The composite sensor 60 of Example 17 is set in the substance adsorption detection system 80 shown in FIG. 11, and substance adsorption detection of the substance to be detected is performed. The incident angle (laser incident angle) of the laser beam to the composite sensor 60 is 28.33 degrees, and the polarization component is TE as described above.

  FIG. 38 shows the humidity detection characteristics of Example 17. The horizontal axis represents time, the left vertical axis represents the oscillation frequency change FS, and the right vertical axis represents the light intensity LI that is the output of the photodetector PD.

After the initial state, the valves 48 and 51 were switched, and dry N ₂ gas and wet N ₂ gas were alternately introduced from the gas introduction cell 61 to the sensing layer 7 of the composite sensor 60. Wet gas was introduced for 5 minutes and dry gas was introduced for 5 minutes. On the way, the introduction of wet gas for 13 minutes and dry gas for 5 minutes was performed. The gas flow rate was about 105 ml / min for wet gas and about 125 ml / min for dry gas. In the next wet section from the initial state, the oscillation frequency shift FS was greatly shifted, and the light intensity LI was also significantly changed and increased. And even if drying and wet were repeated, the oscillation frequency shift FS and the emitted light intensity LI alternately decreased and recovered repeatedly.

(Example 18)
The substrate used for the optical waveguide layer 12, the material of the waveguide layer, the curing conditions, and the film thickness of the clad portion and the core portion were the same as those in Example 14. The thickness of the sensing layer 7 is such that the concentration of CoCl ₂ dispersed PVA is 10 g / l PVA and 30 g / l CoCl ₂ with respect to pure water, so that the ratio of PVA and CoCl ₂ is 1: 3. .4 nm was obtained.

  The composite sensor 60 of Example 18 is set in the substance adsorption detection system 80 shown in FIG. 11, and the substance adsorption detection of the substance to be detected is performed. The incident angle (laser incident angle) of the laser beam to the composite sensor 60 is 28.33 degrees, and the polarization component is TM.

  FIG. 39 shows humidity detection characteristics of Example 18. The horizontal axis represents time, the left vertical axis represents the oscillation frequency change FS, and the right vertical axis represents the light intensity LI that is the output of the photodetector PD. 40 and 41 show enlarged views in which the time axis is extended.

After the initial state, the valves 48 and 51 were switched, and dry N ₂ gas and wet N ₂ gas were alternately introduced from the gas introduction cell 61 to the sensing layer 7 of the composite sensor 60. First, from 10 minutes to 35 minutes in the initial state shown in FIG. 40, the process was repeated with wet gas for 2 minutes and dry gas for 3 minutes. The gas flow rate was about 130 ml / min for wet gas and about 150 ml / min for dry gas. In the initial state, the oscillation frequency shift FS was 0 Hz, and the emitted light intensity LI was 0.25V. In the next wet section, the oscillation frequency shift FS greatly shifted to −1000 Hz. In addition, the light intensity LI changed greatly to 0.6V.

  Next, as shown in FIG. 41, from 30 minutes to 70 minutes, it was repeated while introducing wet gas for 5 minutes and dry gas for 10 minutes, and then changed to introduction of wet gas for 10 minutes and dry gas for 10 minutes. It was. The gas flow rate was about 120 ml / min for wet gas and about 140 ml / min for dry gas. Even in this time zone, the oscillation frequency shift FS and the emitted light intensity LI alternately decreased and recovered repeatedly.

  Even in the substance adsorption detection system using Example 18, a relatively stable humidity detection characteristic was obtained although the base was changed.

(Example 19)
The substrate used for the optical waveguide layer 12, the material of the waveguide layer, the curing conditions, and the film thickness of the clad portion and the core portion were the same as those in Example 14. The thickness of the sensing layer 7 is such that the concentration of CoCl ₂ dispersed PVA is 10 g / l PVA and 30 g / l CoCl ₂ with respect to pure water, so that the ratio of PVA and CoCl ₂ is 1: 3. .4 nm was obtained. The difference between the nineteenth embodiment and the nineteenth embodiment is that the incident angle of the laser beam and the polarization component are TE.

  The composite sensor 60 of Example 19 is set in the substance adsorption detection system 80 shown in FIG. 11, and the substance adsorption detection of the substance to be detected is performed. The incident angle (laser incident angle) of the laser beam to the composite sensor 60 is 28.5 degrees, and the polarization component is TE.

  FIG. 42 shows humidity detection characteristics of Example 19. The horizontal axis represents time, the left vertical axis represents the oscillation frequency change FS, and the right vertical axis represents the light intensity LI that is the output of the photodetector PD. 43 and 44 show enlarged views in which the time axis is extended.

After the initial state, the valves 48 and 51 were switched, and dry N ₂ gas and wet N ₂ gas were alternately introduced from the gas introduction cell 61 to the sensing layer 7 of the composite sensor 60. First, from 0 minute to 25 minutes in the initial state shown in FIG. 43, the process was repeated with wet gas for 2 minutes and dry gas for 3 minutes. The gas flow rate was about 120 ml / min for wet gas and about 140 ml / min for dry gas. In the initial state, the oscillation frequency shift FS was 0 Hz, and the emitted light intensity LI was 0.006V. In the next wet section, the oscillation frequency shift FS greatly shifted to −1000 Hz. In addition, the light intensity LI changed greatly to 0.002V.

  Next, as shown in FIG. 44, the process was repeated from 20 minutes to 40 minutes while introducing wet gas for 10 minutes and dry gas for 10 minutes. The gas flow rate was about 120 ml / min for wet gas and about 140 ml / min for dry gas. Even in this time zone, the oscillation frequency shift FS and the emitted light intensity LI alternately decreased and recovered repeatedly.

  Even in the substance adsorption detection system using Example 19, a relatively stable humidity detection characteristic was obtained although the base was changed.

(Example 20)
Next, as Example 20, a configuration in which the core unit 5 also serves as a sensing layer in the composite sensor 60 of Embodiment 5 will be described. That is, the gas introduction cell 61 is in close contact with the core portion 5 which also serves as a sensing layer in the composite sensor 60 shown in FIG. The composite sensor of Example 20 is set in the substance adsorption detection system shown in FIG. 11, and substance adsorption detection is performed. The incident angle (laser incident angle) of the laser beam to the composite sensor 60 is 28.33 degrees, and the polarization component is TE.

  FIG. 45 shows humidity detection characteristics of Example 20. The horizontal axis represents time, the right vertical axis represents the oscillation frequency change FS, and the left vertical axis represents the light intensity LI, which is the output of the photodetector PD.

After the initial state, the valves 48 and 51 were switched, and dry N ₂ gas and wet N ₂ gas were alternately introduced from the gas introduction cell 61 to the sensing layer 7 of the composite sensor 60. The oscillation frequency shift FS and the emitted light intensity LI repeatedly decreased and recovered alternately.

  In this way, the composite sensor can have the core portion also serving as the sensing layer, but as can be seen from FIG. 45, the characteristics of the oscillation frequency shift FS and the emitted light intensity LI are different from those in Examples 14 to 14 in which the sensing layer is provided separately from the core layer. Compared with Example 19, a slight decrease and recovery are applied to stability.

(Example 21)
This Example 21 also has a configuration in which the core unit 5 also serves as the sensing layer 7 in the composite sensor 60 of the fifth embodiment. The composite sensor of Example 21 is set in the substance adsorption detection system shown in FIG. 11, and substance adsorption detection is performed. The incident angle (laser incident angle) of the laser beam to the composite sensor 60 is 28.33 degrees, and the polarization component is TM.

  FIG. 46 shows the humidity detection characteristics of Example 21. The horizontal axis represents time, the right vertical axis represents the oscillation frequency change FS, and the left vertical axis represents the light intensity LI, which is the output of the photodetector PD.

After the initial state, the valves 48 and 51 were switched, and dry N ₂ gas and wet N ₂ gas were alternately introduced from the gas introduction cell 61 to the sensing layer 7 of the composite sensor 60. The oscillation frequency shift FS and the emitted light intensity LI repeatedly decreased and recovered alternately.

  As described above, in the composite sensor of Example 21, the core portion also serves as the sensing layer. As can be seen from FIG. 46, the characteristics of the oscillation frequency shift FS and the emitted light intensity LI are different from those of Example 14 in which the sensing layer is provided separately from the core layer. ~ Slight reduction and recovery compared to Example 19 on stability.

  As shown in Examples 21 and 22, although the sensitivity may not always be good, in the present invention, the core layer can also be used with the function of the sensing layer. It was confirmed that it was further effective to make an optimum design individually.

(Comparative Example 4)
Next, Comparative Example 4 is given for comparison with Example 14 to Example 21 of Embodiment 5 or 6. Comparative Example 4 is an example in which the gas introduction cell 61 was not used in the composite sensor 60 of Example 18.

That is, the substrate used for the optical waveguide layer 12, the material of the waveguide layer, the curing conditions, and the film thickness of the clad and core portions were the same as those in Example 18. The film thickness of the sensing layer 7 is such that the concentration of CoCl ₂ dispersed PVA is 10 g / l for PVA and 30 g / l for CoCl ₂ with respect to pure water, so that the ratio of PVA and CoCl ₂ is 1: 3. A thickness of 216.4 nm was obtained. Furthermore, the incident angle (laser incident angle) of the laser beam to the composite sensor 60 is 28.33 degrees, and the polarization component is TM.

  FIG. 47 shows humidity detection characteristics of Comparative Example 4. The horizontal axis represents time, the left vertical axis represents the oscillation frequency change FS, and the right vertical axis represents the light intensity LI that is the output of the photodetector PD.

After the initial state, the valves 48 and 51 were switched, and dry N ₂ gas and wet N ₂ gas were alternately introduced into the sensing layer 7 of the composite sensor 60 from the outlet of the pipe 52. As can be seen from FIG. 47, the decrease and recovery of the light intensity LI are unstable. This indicates that the sensor sensitivity falls unless the gas introduction cell is used.

(Comparative Example 5)
Finally, as Comparative Example 5, an example in which an optical waveguide serving as a main waveguide region, which is a main component of the present invention, is not described. In particular, Comparative Example 5 employs a conventional transmission method without using a waveguide layer. Light was incident on the substrate from a substantially vertical direction, and the transmitted light intensity was measured.

  FIG. 48 is a diagram showing a change in emitted light intensity with time. In the section where the wet N 2 gas is introduced, the intensity is slightly higher than in the initial state, but there is no significant intensity change as seen in the embodiment of the present invention using the optical waveguide. When the dry gas is introduced after the wet gas, the emitted light intensity is restored to the initial state.

  In order to construct an optical waveguide, it is necessary to enter light from the edge or from a prism. However, if it is entered from the top without a prism as in the prior art, the light is transmitted without forming a waveguide, as shown in FIG. So that the sensitivity is low. From the above, it is clear that the embodiment using the waveguide as the main component of the present invention has higher sensitivity than the transmission method.

  As an application example of the present invention, by selecting an adsorbent detection substance, detection and identification of an oxidizing gas such as nitrogen oxide, a basic gas such as ammonia, an organic solvent gas, a biological substance in a liquid, etc. Can be considered. Furthermore, it can be used for environmental monitoring and process management.

It is a longitudinal cross-sectional view which shows the structure of the sensor board | substrate in the 1st embodiment of this invention. It is a light absorption characteristic figure of a cobalt chloride dispersion polyvinyl alcohol thin film. It is a longitudinal cross-sectional view which shows the structure of the sensor board | substrate in the 2nd embodiment of this invention. It is a longitudinal cross-sectional view which shows the structure of the sensor board | substrate in the 3rd embodiment of this invention. It is a perspective view which shows the structure of the sensor in the 4th embodiment of this invention. It is a schematic diagram showing a substance adsorption detection system. It is a humidity detection characteristic view obtained by the substance adsorption detection system. 10 is a schematic configuration diagram of a composite sensor according to Embodiment 5. FIG. It is an external view of a gas introduction cell. It is an external view of the gas introduction cell of a double pipe structure. 6 is a schematic diagram of a substance adsorption system having the composite sensor of Embodiment 5. FIG. It is a humidity detection characteristic view obtained by the substance adsorption detection system which has a compound sensor provided with a gas introduction cell. 2 is a plan view and a cross-sectional view of Example 1. FIG. It is the upper side figure and side view of a spin chuck. It is the upper side figure and sectional drawing which set the quartz substrate to the spin chuck. It is a figure which shows the film thickness of the lower clad layer in Example 4, and a core layer. FIG. 10 is a diagram showing the film thicknesses of a lower cladding layer and a core layer in Example 5. It is the top view of a spin jig, and the partial cross section figure of a counterbore part. It is the upper side figure which set the crystal substrate with an electrode to the spin jig, and its partial sectional view. It is the top view and sectional drawing which set the spin jig by which the crystal substrate with an electrode was set in the spin chuck. It is a figure which shows the film thickness of the lower clad layer in Example 6, and a core layer. It is a figure which shows collectively each film thickness, manufacturing method, etc. of the sensor substrate of Examples 1-9. In Example 5 or 9, it is a figure which shows a humidity detection characteristic when the film thickness of a sensing layer is 63 nm. In Example 5 or 9, it is a figure which shows a humidity detection characteristic when the film thickness of the sensing layer 7 is 108 nm. It is a figure which shows the measurement result (alcohol gas detection) at the time of using the sensing layer of Example 12. FIG. It is a figure which shows the measurement result (acetone gas detection) at the time of using the sensing layer of Example 12. FIG. It is another figure which shows the measurement result at the time of using the sensing layer of Example 12 (alcohol gas detection). It is a humidity absorption characteristic figure at the time of forming only PVA into a film and making it into a sensing layer. It is the figure seen from the plane direction of the base material in the specific Example of the sensor structure of this invention in a 4th embodiment. It is a frequency change characteristic view at the time of using various holders. It is a humidity detection characteristic figure of Example 14. It is an expansion humidity detection characteristic view of Example 14. It is an expansion humidity detection characteristic view of Example 14. It is an expansion humidity detection characteristic view of Example 14. It is an expansion humidity detection characteristic view of Example 14. FIG. 18 is a humidity detection characteristic diagram of Example 15. It is a humidity detection characteristic figure of Example 16. FIG. 18 is a humidity detection characteristic diagram of Example 17; FIG. 18 is a humidity detection characteristic diagram of Example 18; FIG. 20 is an enlarged humidity detection characteristic diagram of Example 18. FIG. 20 is an enlarged humidity detection characteristic diagram of Example 18. It is a humidity detection characteristic view of Example 19. It is an expansion humidity detection characteristic view of Example 19. It is an expansion humidity detection characteristic view of Example 19. FIG. 20 is a humidity detection characteristic diagram of Example 20. 22 is a humidity detection characteristic diagram of Example 21. FIG. FIG. 10 is a detection characteristic diagram of Comparative Example 4. 10 is a detection characteristic diagram of Comparative Example 5. FIG.

Explanation of symbols

1 Crystal (substrate)
2 Crystal oscillation electrode 3 Crystal oscillation electrode 4 Clad (optical waveguide)
5 core (optical waveguide)
6 Metal thin film (giving surface plasmon resonance effect)
7 Adsorbed material detection thin film (sensing layer)
8 Light incident prism 9 Light emission prism 17 Adsorbed substance detection thin film (metal colloid layer)
30 Composite sensor 31 Base material 32 Insulating film 40 Substance adsorption detection system 61 Gas introduction cell

Claims (13)

A sensor substrate in which a clad layer, a core layer, and a sensing layer are laminated in this order on at least one surface of a substrate made of a piezoelectric material having electrodes formed on both sides,
The electrode acts as an electrode of a vibrator, and the core layer constitutes an optical waveguide that is a main waveguide region ,
On the sensing layer on the surface on which the sensing layer of the sensor substrate is formed, an entrance prism and an exit prism are arranged so that the optical path of the optical waveguide crosses a portion facing the electrode of the vibrator. A sensor substrate.   The sensor substrate according to claim 1, wherein the piezoelectric material is quartz.   The sensor substrate according to claim 1, wherein the core layer is a resin material.   The sensor substrate according to claim 1, wherein the sensing layer is a resin material containing cobalt chloride.   The sensor substrate according to claim 1, wherein the core layer and / or the cladding layer is a fluorine-containing resin.   The sensor substrate according to claim 4, wherein the water absorption rate of the resin material of the sensing layer is larger than the water absorption rate of the resin material of the core layer.   The sensor substrate according to claim 1, wherein a metal thin film layer is formed between the core layer and the sensing layer. Using the sensor substrate according to any one of claims 1 to 7,
Wherein the sensor substrate is supported, the surface of the substrate is coated with insulating material except for the contact between the electrode lead portion of the sensor substrate by the pressing of the two prisms and the substrate Combined optical waveguide and quartz crystal sensor.   9. The substrate according to claim 8, wherein a substrate having an opening or a counterbore provided at least at a portion facing the electrode is disposed on a surface opposite to the surface on which the sensing layer is formed. Compound sensor. Between the incident prism and the emission prism on the surface of the sensor substrate where the sensing layer is formed,
The composite sensor according to claim 8 or 9, wherein a gas introduction cell for introducing a gas containing a substance to be detected into the sensor substrate is provided in close contact with the sensing layer.   The composite sensor according to claim 10, wherein the gas introduction cell uses silicon rubber in a close contact portion with the sensing layer.   12. The composite sensor according to claim 10, wherein the gas introduction cell has an exhaust port for exhausting the gas.   The composite sensor according to claim 10, wherein the gas introduction cell has a double pipe structure.

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