Chemical sensor, chemical sensor module, chemical detection apparatus, and chemical detection method

A chemical sensor according to an embodiment of the present technology includes a substrate, a low refractive index layer, a high refractive index layer, and a light detection unit. The low refractive index layer is laminated on the substrate and has a second refractive index smaller than a first refractive index that is a refractive index of a detection target object. The high refractive index layer is laminated on the low refractive index layer, has a third refractive index larger than the first refractive index, and includes a holding surface on which the detection target object is held, and illumination light propagates therein. The light detection unit is provided on the substrate and detects detection target light generated from the detection target object by the illumination light.

TECHNICAL FIELD

The present technology relates to a chemical sensor, a chemical sensor module, a chemical detection apparatus, and a chemical detection method for detecting chemicals using light emission due to a chemical bond.

BACKGROUND ART

A chemical sensor that detects chemicals using light emission due to a chemical bond has been studied. Specifically, if a probe material specifically bonding to a target material to be detected is adhered to the sensor and a sample is supplied to the sensor, a target material included in the sample bonds to the probe material. For example, by using a fluorescent label that can be introduced into a composite material of a target material and a probe material to cause the composite material to emit light, it is possible to detect the emitted light by a photoelectric conversion element. By causing a plurality of types of probe materials to be adhered to the sensor, it is also possible to specify the type of the target material included in the sample.

In such a chemical sensor, in order to perform the detection with high sensitivity and high accuracy, it is necessary to introduce only emitted light generated due to the bond between the target material and the probe material into the photoelectric conversion element and to eliminate light other than that, e.g., excitation light for generating fluorescent light.

For example, Patent Document 1 discloses a “biosensor with evanescent waveguide and integrated sensor” that uses an evanescent wave (near-field light) of excitation light to cause a sample to emit fluorescent light, similarly. The sensor has a configuration in which a detector, a filter, a contact cladding layer, and a waveguide layer are laminated in the stated order, and a sample is placed on the waveguide layer. It has a configuration in which excitation light (laser) is introduced into the waveguide layer in a direction parallel to the layer, and the detector detects the fluorescent light the fluorescent light from the sample that is excited with an evanescent wave leaked from the interface of the waveguide layer.

Moreover, Patent Document 2 discloses an “all polymer optical waveguide sensor” that uses an evanescent wave of excitation light to cause a sample to emit fluorescent light. The sensor has a configuration in which a polymer waveguide is formed on a polymer substrate, and a sample is fixed on the polymer substrate. The sample is excited with an evanescent wave of a light wave (coherent light) traveling through the polymer waveguide, and generates fluorescent light, which is detected by a detector.

In any of the inventions described in Patent Document 1 and Patent Document 2, the excitation light is confined in the waveguide structure to prevent the excitation light from reaching the photoelectric conversion element. Therefore, the evanescent wave for causing the sample fixed on the waveguide structure to emit fluorescent light is an element in both inventions.

CITATION LIST

Patent Document

DISCLOSURE OF THE INVENTION

Problem to be Solved by the Invention

However, because the intensity of the evanescent wave is much smaller than the intensity of light introduced into the waveguide structure, the inventions described above cannot use optical energy efficiently. Furthermore, because the thickness of the waveguide structure is limited (to several ten nm) to use the evanescent wave in the optimal conditions, the manufacture of the sensor is considered to be difficult or to cost a lot. Furthermore, because the travel distance of the evanescent wave is very small (about several ten nm), if a fluorescent material is not present in the vicinity of the surface of the sample (within the travel distance of the evanescent wave), it cannot be detected.

In view of the circumstances as described above, it is an object of the present technology to provide a chemical sensor, a chemical sensor module, a chemical detection apparatus, and a chemical detection method that are capable of detecting chemicals with high accuracy and high sensitivity.

Means for Solving the Problem

In order to achieve the above-mentioned object, a chemical sensor according to an embodiment of the present technology includes a substrate, a low refractive index layer, a high refractive index layer, and a light detection unit.

The low refractive index layer is laminated on the substrate and has a second refractive index smaller than a first refractive index that is a refractive index of a detection target object.

The high refractive index layer is laminated on the low refractive index layer, has a third refractive index larger than the first refractive index, and includes a holding surface on which the detection target object is held, and illumination light propagates therein.

The light detection unit is provided on the substrate and detects detection target light generated from the detection target object by the illumination light.

According to this configuration, the illumination light introduced into the high refractive index layer is refracted and transmitted to the detection target object, and the first refractive index being a refractive index of the detection target object is larger than the second refractive index being a refractive index of the low refractive index layer as described above. Therefore, by causing the illumination light to enter the high refractive index layer at an appropriate incidence angle, it is possible to cause the illumination light to be refracted and transmitted to the detection target object while causing the illumination light to be totally reflected on the interface of the high refractive index layer and the low refractive index layer. Therefore, it is possible to detect the detection target light generated from the detection target object by the light detection unit while preventing the illumination light from reaching the light detection unit located below the low refractive index layer. Therefore, it is possible to prevent the detection accuracy of the illumination light by the light detection unit from lowering.

The holding surface may further have adsorption regions to which the detection target object is adsorbed and non-adsorption regions to which the detection target object is not adsorbed.

According to this configuration, because the non-adsorption region is not in contact with the detection target object that causes the illumination light to be refracted and transmitted thereto, it is possible to prevent the refraction and transmission of the illumination light in the non-adsorption region from occurring. That is, in the case where the non-adsorption region faces air or is in contact with at least a material having a refractive index sufficiently smaller than a refractive index of the detection target object (first refractive index), the illumination light may be totally reflected in the non-adsorption region. Accordingly, because the illumination light reaches the detection target object on the adsorption region but is totally reflected on the non-adsorption region, it is possible to prevent the optical energy from being lost.

The adsorption regions may be separated by the non-adsorption regions.

According to this configuration, because the adsorption regions can be disposed in an island shape, it is possible to detect various types of chemicals at the same time by causing different target materials to be adsorbed in the respective adsorption regions.

The light detection unit may include a plurality of light detection units, and the adsorption regions may be opposed to the light detection units, respectively.

According to this configuration, because the one-to-one relationship is established between the detection target object adsorbed to the respective adsorption regions and the light detection unit, it is possible to detect the detection target light with high accuracy.

The light detection unit may include a plurality of light detection units, and the respective adsorption regions may be opposed to the plurality of light detection units.

According to this configuration, because the detection target object adsorbed to the respective adsorption regions corresponds to the plurality of light detection units, it is possible to confirm the properties of light emission spectrum of the detection target light in one adsorption region.

The adsorption regions may be formed in such a way that an area thereof is increased along a direction in which the illumination light propagates.

According to this configuration, it is possible to cause a uniform amount of illumination light to enter the respective adsorption regions. As described above, because the illumination light is totally reflected on the non-adsorption region, the optical energy is not lost. However, in the adsorption area, it is lost by entering the detection target object. That is, in the adsorption area located at a long distance in the direction in which the illumination light propagates, the intensity of the illumination light per unit surface is small, as compared with the adsorption region located at a short distance. Here, as in this configuration, by gradually increasing the size of the adsorption region, it is possible to adjust the proportion of the amount of light entering the detection target object and the amount of light totally reflected, and to cause a uniform amount of illumination light to enter the respective adsorption region.

The adsorption regions may be formed by hydrophilic processing applied to the holding surface, and the non-adsorption regions may be formed by hydrophobic processing applied to the holding surface.

According to this configuration, the adsorption region and the non-adsorption region can be segmented in the case where the detection target object includes a hydrophilic material.

The adsorption regions may be formed by hydrophobic processing applied to the holding surface, and the non-adsorption regions may be formed by hydrophilic processing applied to the holding surface.

According to this configuration, the adsorption region and the non-adsorption region can be segmented in the case where the detection target object includes a hydrophobic material.

The non-adsorption regions may be covered by a coating film to which the detection target object is not adsorbed, and the adsorption regions do not have to be covered by the coating film.

According to this configuration, the adsorption region and the non-adsorption region can be segmented in the case where the detection target object includes a material that can be adsorbed to the holding surface.

The coating film may have light reflectivity.

According to this configuration, it is possible to reflect the illumination light by the coating film. This is particularly effective in the case where a material having a high refractive index is laminated on the non-adsorption region.

The above-mentioned chemical sensor may further include a color filter that is provided between the light detection unit and the low refractive index layer, and blocks wavelengths other than that of the detection target light.

According to this configuration, it is possible to secondarily prevent the illumination light from reaching the light detection unit. As described above, because the illumination light is totally reflected on the interface of the high refractive index layer and the low refractive index layer, it does not reach the light detection unit in principle. However, for example, the case where it reaches the light detection unit through the same path as that of the detection target light by being reflected on the detection target object is conceivable. Here, by removing such an illumination light component with a color filter, it is possible to detect the detection target light with higher accuracy.

The chemical sensor may further include an on-chip lens that is provided between the light detection unit and the low refractive index layer, and collects the detection target light on the light detection units.

According to this configuration, it is possible to collect the detection target light on the light detection unit by the on-chip lens, and thus to detect the detection target light with higher accuracy.

The chemical sensor may further include light blocking walls that are provided on the low refractive index layer and partition the low refractive index layer into areas opposed to the respective light detection units.

According to this configuration, it is possible to block the detection target light generated from an adjacent detection target object, and to prevent cross talk from occurring.

The illumination light may be excitation light, and the detection target light may be fluorescent light.

In order to achieve the above-mentioned object, a chemical sensor module according to an embodiment of the present technology includes a chemical sensor and a light introduction unit.

The chemical sensor includes a substrate, a low refractive index layer that is laminated on the substrate and has a second refractive index smaller than a first refractive index that is a refractive index of a detection target object, a high refractive index layer in which illumination light propagates, which is laminated on the low refractive index layer, has a third refractive index larger than the first refractive index, and includes a holding surface on which the detection target object is held, and a light detection unit that is provided on the substrate and detects detection target light generated from the detection target object by the illumination light.

The light introduction unit is joined to the chemical sensor and introduces the illumination light into the high refractive index layer.

In order to achieve the above-mentioned object, a chemical detection apparatus according to an embodiment of the present technology includes a chemical sensor module and a light source.

The chemical sensor module includes a chemical sensor including a substrate, a low refractive index layer that is laminated on the substrate and has a second refractive index smaller than a first refractive index that is a refractive index of a detection target object, a high refractive index layer in which illumination light propagates, which is laminated on the low refractive index layer, has a third refractive index larger than the first refractive index, and includes a holding surface on which the detection target object is held, and a light detection unit that is provided on the substrate and detects detection target light generated from the detection target object by the illumination light, and a light introduction unit that is joined to the chemical sensor and introduces the illumination light into the high refractive index layer.

The light source applies the illumination light to the light introduction unit.

In order to achieve the above-mentioned object, a chemical detection method according to an embodiment of the present technology includes preparing a chemical sensor including a substrate, a low refractive index layer that is laminated on the substrate and has a second refractive index smaller than a first refractive index that is a refractive index of a detection target object, a high refractive index layer in which illumination light propagates, which is laminated on the low refractive index layer, has a third refractive index larger than the first refractive index, and includes a holding surface on which the detection target object is held, and a light detection unit that is provided on the substrate and detects detection target light generated from the detection target object by the illumination light.

By a light introduction unit, the illumination light is introduced into the high refractive index layer.

By the light detection unit, the detection target light is detected.

Effect of the Invention

As described above, according to the present technology, it is possible to provide a chemical sensor, a chemical sensor module, and a chemical detection method that are capable of detecting chemicals with high accuracy and high sensitivity.

MODE(S) FOR CARRYING OUT THE INVENTION

First Embodiment

A chemical sensor according to a first embodiment of the present technology will be described.

[Configuration of Chemical Sensor]

FIG. 1is a cross-sectional view showing a configuration of a chemical sensor1according to the first embodiment. As shown in the figure, the chemical sensor1has a configuration in which a substrate2, a low refractive index layer3, and a high refractive index layer4are laminated in the stated order. Moreover, a detection target object covers the chemical sensor1when the chemical sensor1is used.FIG. 2is a cross-sectional view showing detection target objects S placed on the chemical sensor1.

In the following description, the refractive index (absolute refractive index, the same shall apply hereinafter) of the detection target object S is referred to as a first refractive index n1, the refractive index of the low refractive index layer3is referred to as a second refractive index n2, and the refractive index of the high refractive index layer4is referred to as a third refractive index n3. Although the details will be described later, these refractive indexes have a relationship of increasing in the order of the second refractive index n2, the first refractive index n1, and the third refractive index n3.

On the substrate2, light detection units21are provided. The light detection unit21may each be an image sensor (CMOS, CCD, or the like) in which pixels (photoelectric conversion elements) are two-dimensionally arranged, and various sensors such as a line sensor in which pixels are one-dimensionally arranged and a photosensor using organic photoelectric conversion that are capable of detecting light can be used. On the substrate2, a wiring or the like (not shown) that is connected to the light detection unit21may be provided. InFIG. 1andFIG. 2, a protective insulating film22of the image sensor is provided on the substrate2. However, it is not provided depending on the configuration of the light detection unit21in some cases.

The low refractive index layer3is a layer laminated on the substrate2, and has the second refractive index n2 smaller than the first refractive index n1 (refractive index of the detection target objects S). That is, the low refractive index layer3can be formed of a material having a refractive index that is more than 1 (air) and less than the first refractive index (e.g., 1.5). In addition, as a material of the low refractive index layer3, a material having at least high optical transparency in the wavelength range of light to be detected (hereinafter, referred to as detection target light) to be described later is favorable.

Examples of such a material include fluorine containing-hollow silica particle-containing polysiloxane resin (n=1.2 to 1.35 (depending on silica particle size)), fluorine-containing polysiloxane resin (n=1.42), fluorine-containing acrylic resin (n=1.42), and hollow silica particle-containing polysiloxane resin (n=1.2 to 1.35) depending on silica particle size)). It should be noted that the refractive index shown here is a refractive index with respect to an optical wavelength of 550 nm.

The thickness of the low refractive index layer3is favorably not less than 50 nm and not more than 1 mm, and is more favorably not less than 100 nm and not more than 1 μm, or not less than 50 μm and not more than 500 μm.

The high refractive index layer4is a layer laminated on the low refractive index layer3, and has the third refractive index n3 larger than the first refractive index n1 (refractive index of the detection target object S). That is, the high refractive index layer4can be formed of a material having a refractive index higher than the first refractive index (e.g., 1.5). In addition, as a material of the high refractive index layer4, a material having at least high optical transparency in the wavelength range of the detection target light is favorable. Furthermore, a material having high optical transparency in the wavelength range of light to be introduced into the high refractive index layer4(hereinafter, referred to as illumination light) to be described later is favorable.

Examples of such a material include silicon nitride (n=1.9), silicon nitride oxide (n=1.85), titanium oxide dispersion polysiloxane resin (n=1.8), and titanium oxide dispersion acrylic resin to which a thermosetting material is added (n=1.8). It should be noted that the refractive index shown here is a refractive index with respect to an optical wavelength of 550 nm.

The thickness of the high refractive index layer4is not particularly limited, but is favorably thin to prevent the detection target light from attenuating. The high refractive index layer4may be directly deposited on the low refractive index layer3or may be laminated by bonding a plate-like member formed of the above-mentioned material to a part obtained by laminating the low refractive index layer3on the substrate2.

As shown inFIG. 2, the surface of the high refractive index layer4is a surface on which the detection target objects S are held. Hereinafter, the surface is referred to as holding surface4a. The holding surface4acan be segmented into regions to which the detection target objects S are adsorbed. Hereinafter, the region to which the detection target object S is adsorbed is referred to as adsorption region, and the region to which the detection target object S is not adsorbed is referred to as non-adsorption region.

FIG. 3is a schematic diagram showing adsorption regions4a1and non-adsorption regions4a2formed on the holding surface4a. As shown in the figure, the adsorption regions4a1may be regions surrounded by the non-adsorption regions4a2. By partitioning the holding surface4ain this way, different types of detection target objects S can be arranged on the respective adsorption regions4a1. Further, it is possible to cause the detection target objects S that cover the respective adsorption regions4a1to be opposed to the respective light detection units21in the one-to-one relationship.

It should be noted that the adsorption region4a1is not limited to the case where it is formed with respect to the light detection unit21with the one-to-one relationship, and the plurality of adsorption regions4a1may be formed to be opposed to one light detection unit21. However, with the one-to-one relationship, it is possible to improve the detection accuracy.

It is assumed that the chemical sensor1in the state where surface processing is applied thereto as described above is supplied to a user, and the user use the chemical sensor1by covering the adsorption regions4a1with arbitrary detection target objects S, for example.

The adsorption regions4a1and the non-adsorption region4a2can be segmented by surface processing on the holding surface4a. Specifically, in the case where the detection target objects S include a hydrophilic material, a region to which hydrophilic processing is applied can be assumed to be the adsorption region4a1, and a region to which hydrophobic is applied can be assumed to be the non-adsorption region4a2. In addition, in the case where the detection target objects S include a hydrophobic material, a region to which hydrophobic processing is applied can be assumed to the adsorption region4a1, and a region to which hydrophilic processing is applied can be assumed to be the non-adsorption region4a2.

Moreover, the adsorption regions4a1and the non-adsorption region4a2can be segmented by a coating film deposited on the holding surface4a. Specifically, in the case where the holding surface4aincludes a material to which the detection target object S is adsorbed, by forming a coating film formed of a material to which the detection target object S is not adsorbed, a region on which the coating film is formed can be assumed to be the non-adsorption region4a2and a region on which the coating film is not formed can be assumed to be the adsorption region4a1. In addition, although the details will be described later, the coating film favorably has light reflectivity, and may be an aluminum coating film, for example.

It should be noted that the entire region of the holding surface4acan be assumed to be the adsorption region4a1, and the non-adsorption region4a2may not be formed. In this case, the entire region of the holding surface4ais covered by the detection target objects S uniformly.

[Configuration of Chemical Sensor Module]

The above-mentioned chemical sensor1can be used as a chemical sensor module.FIG. 4is a cross-sectional view showing a chemical sensor module5. As shown in the figure, a light introduction unit6is joined to the chemical sensor1, thereby forming the chemical sensor module5.

The light introduction unit6is a member that introduces light into the high refractive index layer Oat a predetermined angle. The details of the incidence angle of light will be described later. The light introduction unit6can be a light introduction prism joined to the high refractive index layer4as shown inFIG. 4, and may be another member that is capable of introducing light into the high refractive index layer4at a predetermined angle. The light introduction unit6can be joined to the high refractive index layer4via index matching oil or the like so that an air layer does not enter between the light introduction unit6and the high refractive index layer4.

The light introduction unit6is not necessarily arranged on the high refractive index layer4.FIG. 5andFIG. 6are schematic diagrams showing different examples of arrangement of the light introduction unit6. The light introduction unit6may be on the upper layer side of the high refractive index layer4as shown inFIG. 5, and may be on the lower layer side of the high refractive index layer4as shown inFIG. 6. In addition, a plurality of light introduction units6may be provided so that illumination light (to be described later) can be introduced into the high refractive index layer4from a plurality of directions.

[Configuration of Chemical Detection Apparatus]

The chemical sensor module5can be used as the chemical detection apparatus together with a light source.FIG. 22is a schematic diagram showing the configuration of the chemical detection apparatus. As shown in the figure, a chemical detection apparatus10includes the chemical sensor module5and a light source11. In addition, a lens12is provided between the chemical sensor module5and the light source11.

The illumination light emitted from the light source11can be made to be parallel light by the lens12, and can enter the high refractive index layer4via the light introduction unit6. It is favorable that the incidence angle of the illumination light on the high refractive index layer4can be changed depending on the position or angle of the light source11and the lens12.

[Detection of Target Material Using Chemical Sensor]

A method of detecting a target material using the chemical sensor1(and the chemical sensor module5) will be described.

If various kinds of probe materials are adsorbed to the adsorption regions4a1and a sample including a target material is supplied to the chemical sensor1, the target material in the sample specifically bonds to a predetermined probe material. A fluorescent label material that is capable of performing fluorescent labeling of a composite material of a target material and a probe material is supplied to the chemical sensor1, only the detection target object S including the composite material of a target material and a probe material is fluorescent-labeled. By detecting the fluorescent light, it is possible to specify the target material included in the sample.

In addition, the target material may be subjected to fluorescent labeling in advance. In this case, because the target material that is not bonded to the probe material adsorbed to the adsorption regions4a1is removed from the chemical sensor1, it is possible to use the fluorescent light to specify the target material, similarly to the above. In addition, the target material may be specified by applying fluorescent labeling to the probe material in advance and detecting the wavelength and change in luminance of the fluorescent light generated due to the bonding of the probe material and the target material.

As described above, the chemical sensor1can specify the target material by detecting fluorescent light generated from the detection target object S, it is important to measure the fluorescent light accurately. If the light detection unit21detects excitation light for generating fluorescent light, a value of the intensity of fluorescent light different from that of normal fluorescent light is output from the light detection unit21. However, in the chemical sensor1according to the present technology, the excitation light is prevented from reaching the light detection unit21by a mechanism to be described later, i.e., the fluorescent light can be measured accurately.

It should be noted that here, although the description has been made that fluorescent light generated from the detection target object S by the irradiation of excitation light is detected by the light detection unit21, but it is not limited thereto. It is only necessary that if some kind of light is applied to the detection target object S, some kind of light is generated from the detection target object S. For example, the case where scattered light is generated from the detection target object S only in the case where the detection target object S includes a specific material is conceivable.

In the following description, light applied to the detection target object S as in the above-mentioned excitation light is referred to as “illumination light”, and light generated from the detection target object S by the irradiation of light as in the fluorescent light is referred to as “detection target light.”

The chemical sensor1can be used in the following fields. The fields include chemical or biochemical analysis including analysis of biological fluid such as yolk, blood, serum and plasma, environmental analysis including analysis of water, dissolved soil extract, and dissolved plant extract, chemical production, particularly analysis in a dye solution or a reaction solution, dispersion or formulation analysis, quality protection analysis, and gene analysis.

[Operation of Chemical Sensor]

The operation of the chemical sensor1(and the chemical sensor module5) will be described.FIG. 7is a schematic diagram showing the operation of the chemical sensor1.

First, the case where the detection target objects S do not cover the holding surface4aof the high refractive index layer4will be described. As shown inFIG. 7(a), illumination light is introduced into the high refractive index layer4via the light introduction unit6. The illumination light enters the holding surface4aof the high refractive index layer4within a predetermined angle range, but the angle range will be described later.

Here, because the refractive index of the high refractive index layer4(third refractive index n3) is larger than air (refractive index n=1) and the refractive index of the low refractive index layer3(the second refractive index n2) as described above, total reflection of the illumination light that has entered within the appropriate angle range is repeated on the interface of the high refractive index layer4and air and the interface of the high refractive index layer4and the low refractive index layer3, and the illumination light propagates in the high refractive index layer4as shown inFIG. 7(a). That is, in this state, the illumination light propagates in the high refractive index layer4without leaking to the outside.

Next, the case where the detection target objects S cover the holding surface4awill be described. As shown inFIG. 7(b), by causing the illumination light to enter the high refractive index layer4at an appropriate incident angle, the illumination light that has reached the adsorption regions4a1on which the detection target object S is provided is refracted and transmitted thereto without being totally reflected thereon, and then enters the detection target object S. This is because the refractive index of the detection target object S (first refractive index n1) is larger than the refractive index of air.

On the other hand, light that has reached the non-adsorption region4a2on which the detection target object S is not provided is totally reflected thereon similarly to the above, and propagates in the high refractive index layer4again.

That is, it is possible to cause the illumination light to enter the detection target object S in a region (the adsorption regions4a1) on which the detection target object S exists, and cause the illumination light to be totally reflected on a region (the non-adsorption region4a2) on which the detection target object S does not exist. In addition, also in this case, because the refractive index of the low refractive index layer3(the second refractive index n2) is smaller than the refractive index of the detection target object S (the first refractive index n1), the illumination light is totally reflected on the interface of the high refractive index layer4and the low refractive index layer3.

Therefore, in this state, the illumination light enters only the detection target object S while propagating in the high refractive index layer4. Because the illumination light does not leak from the non-adsorption region4a2on which the detection target object S does not exist, optical energy is not lost. Because the illumination light does not reach the light detection unit21, the illumination light is not detected by the light detection unit21.

Moreover, also in the case where the non-adsorption region4a2is formed of a coating film including a material to which the detection target object S is not adsorbed, by using the coating film having light reflectivity, it is possible to prevent the illumination light from leaking from the non-adsorption region4a2. Also in this case, it is possible to prevent optical energy to be lost or the illumination light to be detected by the light detection unit21.

As shown inFIG. 7(c), the illumination light that has entered the detection target object S generates the detection target light (fluorescent light or the like) from the detection target object S, and the detection target light is detected by the light detection unit21. Although the detection target light is emitted from the detection target object S in all directions, a part thereof is transmitted through the high refractive index layer4and the low refractive index layer3and is detected by the light detection unit21. It should be noted that because the detection target light enters the high refractive index layer4at a steep incidence angle, it reaches the light detection unit21without being totally reflected on the interface of the high refractive index layer4or the like.

As described above, according to the configuration of the chemical sensor1of this embodiment, the illumination light that has entered the high refractive index layer4does not reach the light detection unit21and it is possible to prevent the illumination light from being detected by the light detection unit21. Furthermore, the illumination light that has entered the high refractive index layer4does not attenuate except when it enters the detection target object S. That is, it is possible to use the optical energy effectively.

[Regarding Incidence Angle of Illumination Light]

Although the case where the illumination light enters the high refractive index layer4at an appropriate incidence angle in the operation of the chemical sensor1described above has been described, the incidence angle will be described in detail.

FIG. 8is a schematic diagram showing the interface of the high refractive index layer4and the low refractive index layer3. Assuming that the incidence angle of the illumination light (shown by arrows in the figure) on the interface is an angle θ3 and an output angle of the illumination light from the interface is an angle θ2, the relationship of the following equation (1) is established according to the Snell's law.
n3×sin θ3=n2×sin θ2  (1)

As described above, because the third refractive index n3 is larger than the second refractive index n2, the angle θ3 exists such that the angle θ2 is not less than 90°. In this state, the illumination light cannot be refracted and transmitted from the high refractive index layer4to the low refractive index layer3, is totally reflected, and returns to the high refractive index layer4.

FIG. 9is a schematic diagram showing the interface of the high refractive index layer4and the detection target object S. In the non-adsorption region4a2that is not covered by the detection target object S, because the refractive index of air n=1, and is smaller than the third refractive index n3, the illumination light is totally reflected at the angle θ3 such that the angle θ2 is not less than 90°.

Moreover, the illumination light is refracted and transmitted from the interface to the detection target object S in the adsorption regions4a1, as described above. Assuming that an output angle of the illumination light from the interface is an angle θ1, the following equation (2) is satisfied similarly to the equation (1).
n3×sin θ3=n2×sin θ2=n1×sin θ1  (2)

Because the first refractive index n1 is larger than the second refractive index n2, θ1<90° from the equation (2) even in the case where the angle θ2 is 90°. That is, the illumination light is refracted and transmitted to the detection target object S.

As described above, the incidence angle of the illumination light on the high refractive index layer4can be selected depending on the respective values of the first refractive index n1, the second refractive index n2, and the third refractive index n3. Accordingly, it is possible to cause the illumination light to be totally reflected on the interface of the low refractive index layer3and the non-adsorption region4a2and to cause the illumination light to be refracted and transmitted on the interface with the adsorption regions4a1(detection target object S).

FIG. 10is a table showing incidence angles at which total reflection of the illumination light occurs with respect to the values of the first refractive index n1 (detection target object S), the second refractive index n2 (low refractive index layer3), and the refractive index3(high refractive index layer4). For example, in the case where the third refractive index n3 is 1.9, the second refractive index n2 is 1.3, and the first refractive index n1 is 1.4, from the table, total reflection occurs if the incidence angle is not less than 43.2°. In addition, if the incidence angle is less than 47.5°, refraction and transmission to the detection target object S occurs. That is, if the incidence angle is not less than 43.2° and less than 47.5°, it is possible to cause the illumination light to be refracted and transmitted to only the detection target object S, and to be totally reflected on another interface.

[Method of Manufacturing Chemical Sensor]

A method of manufacturing the chemical sensor1(and the chemical sensor module5) will be described.FIG. 11is a schematic diagram showing a method of manufacturing the chemical sensor1.

As shown inFIG. 11(a), the light detection unit21including an impurity region is formed on a surface of the substrate2formed of, for example, single crystal silicon by ion-implantation from a mask and the subsequent heat treatment, and the like. Next, as shown inFIG. 11(b), the protective insulating film22is formed on the substrate2on which the light detection unit21is formed.

Next, as shown inFIG. 11(c), the low refractive index layer3is laminated on the protective insulating film22. The low refractive index layer3can be formed by, for example, applying raw material resin by a method such as spin coating and drying it.

Furthermore, as shown inFIG. 11(d), the high refractive index layer4is laminated on the low refractive index layer3. The low refractive index layer3can be formed by, for example, applying raw material resin by a method such as spin coating and drying it. It should be noted that the high refractive index layer4can be formed by printing or applying a resin sheet.

Moreover, the high refractive index layer4can be formed by applying a plate-like member on the low refractive index layer3.FIG. 12is a schematic diagram showing a method of manufacturing the chemical sensor1in accordance with this method. Specifically, thin plate glasses such as L-LAH84 (n=1.80), L-NBH (n=1.92), S-LAH79 (n=2.0), and L-BBH1 (n=2.10), which are manufactured by OHARA INC. and have high refractive index, are prepared.

As shown inFIG. 12(a), to a thin plate glass G, a resin sheet F having a low (n=about 1.4) refractive index is applied by vacuum lamination. Next, as shown inFIG. 12(b), the thin plate glass G is applied to the low refractive index layer3by vacuum lamination with the resin sheet F side being the low refractive index layer3side.

Next, the adsorption regions4a1and the non-adsorption region4a2are formed on the holding surface4aof the high refractive index layer4. In the case where a hydrophilic material is scheduled to be used as the detection target object S, a region to which hydrophilic processing is applied can be the adsorption regions4a1, and a region to which hydrophobic processing is applied can be the non-adsorption region4a2. In addition, in the case where a hydrophobic material is scheduled to be used as the detection target object S, a region to which hydrophobic processing is applied can be the adsorption regions4a1, and a region to which hydrophilic processing is applied can be the non-adsorption region4a2. Furthermore, a metal thin film is formed on the holding surface4a, which can be the non-adsorption region4a2.

In this way, the chemical sensor1can be manufactured. Furthermore, by joining the light introduction unit6to the chemical sensor1, the chemical sensor module5can be manufactured.FIG. 13is a schematic diagram showing a mode in which the light introduction unit6is joined to the chemical sensor1. As shown inFIG. 13(a), in the chemical sensor1, a sensor region A in which the light detection unit21is formed is provided, and terminals B for joining the chemical sensor1to another member are provided on three sides thereof.

In this case, the light introduction unit6is joined to a region for light introduction unit C on which the terminal B is not provided, via index matching oil, for example. Accordingly, as shown inFIG. 13(b), the light that has entered the light introduction unit6propagates in the high refractive index layer4periodically. In this way, the chemical sensor module5can be manufactured.

Second Embodiment

A chemical sensor according a second embodiment of the present technology will be described. It should be noted that in this embodiment, the same configurations as those of the chemical sensor according to the first embodiment will be denoted by the same reference symbols and a description thereof will be omitted. The chemical sensor according to this embodiment has the same layered structure as the chemicals sensor according to the first embodiment, but has an adsorption region that is covered by a detection target object, which is different from that of the first embodiment.

FIG. 14is a schematic diagram showing a chemical sensor201according to this embodiment. As shown in the figure, adsorption regions204a1of the chemical sensor201are formed such that the area thereof increases for every three columns from the side of the light introduction unit6. In other words, non-adsorption regions204a2that separate the adsorption regions204a1are formed such that they get thin for every three columns. It should be noted that the area of the adsorption regions204a1is not limited to the case of increasing for every three columns, and can increase for every columns, ever two columns, or every multiple columns.

By making the adsorption region204a1to have such a configuration, it is possible to cause uniform amounts of illumination light to enter the detection target objects S. As described in the first embodiment, by entering the detection target object S, the illumination light that propagates in the high refractive index layer4attenuates as it moves away from the light introduction unit6. Therefore, the intensity of the illumination light per unit area decreases in the adsorption region204a1that is distant from the light introduction unit6as compared with the adsorption region204a1that is close to the light introduction unit6.

Accordingly, by increasing the area of the adsorption region204a1opposed to the light detection unit21such that the area increases with the increasing distance from the light introduction unit6, it is possible to cause uniform amounts of illumination light to enter the adsorption regions204a1.

Hereinafter, the area ratio (opening ratio) of the adsorption region204a1and the non-adsorption region204a2will be described in detail. As described above, the illumination light introduced into the high refractive index layer4propagates in the high refractive index layer4while being totally reflected on the interface. The illumination light is emitted from the adsorption region204a1(hereinafter, opening) for every total reflection. Therefore, assuming that the number of times of total reflection is n, the proportion of the size of a side of the adsorption region204a1(hereinafter, opening size) is Xn, and the amount of emitted illumination light from the opening at the n-th total reflection is In, the following equation (3) is satisfied.

Moreover, if all illumination light is considered to be emitted at the time of the propagation of the illumination up to the n-th total reflection, assuming that the total amount of illumination light is 1 and the amount of illumination light emitted from the opening of each place is obtained by dividing the total amount illumination light by the number of times of total reflection, i.e., equal, the following formula (4) is satisfied.
1=I1/n+I2/n+I3/n+ . . . +In/n(4)

FIG. 15is a table showing the amount of illumination light in the case where the number of times of total reflection is 4 and the illumination light is applied to the entire surface of the holding surface4a. As shown in the figure, by setting the ratio of the opening size to 50% in the case of openings within the range of the 1st total reflection, to 57.7% in the case of openings within the range of the 2nd total reflection, to 70.7% in the case of openings within the range of the 3rd total reflection, and to 100% in the case of openings within the range of the 4th total reflection, it is possible to equally illuminate the entire surface.

It should be noted that because the opening is connected to an adjacent opening in the case where the opening size is 100%, there is a need to set an upper limit of the opening size actually. Therefore, the case where the maximum opening size is set to about 90% is conceivable.FIG. 16is a table showing the amount of illumination light in the case where the number of times of total reflection is 4, the illumination light is applied to the entire surface of the holding surface4a, and the opening size is about 90%.

Moreover, the case where the number of times of total reflection is 8 and the illumination light is applied to the entire surface of the holding surface4ais as follows.FIG. 17is a table showing the amount of illumination light in the case where the number of times of total reflection is 8 and the illumination light is applied to the entire surface of the holding surface4a.

As described above, by increasing the area of the adsorption region204a1with the increasing distance from the light introduction unit6, it is possible to cause uniform amounts of illumination light to enter the detection target objects S.

Third Embodiment

A chemical sensor according to a third embodiment of the present technology will be described. It should be noted that in this embodiment, the same configurations as those of the chemical sensor according to the first embodiment will be denoted by the same reference symbols and a description thereof will be omitted. The chemical sensor according to this embodiment is obtained by adding on-chip lenses and color filters to the layered structure of the chemical sensor according to the first embodiment.

FIG. 18is a cross-sectional view showing the configuration of a chemical sensor301according to this embodiment. As shown in the figure, the chemical sensor301includes color filters302and on-chip lenses303in addition to the substrate2, the low refractive index layer3, and the high refractive index layer4. The color filters302and the on-chip lenses303are formed on the substrate2in the stated order.

The color filters302can be one that has optical properties in which the detection target light is transmitted and the illumination light is blocked. As described above, the illumination light does not leak from the high refractive index layer4to the side of the light detection unit21in principle. However, the case where the illumination light that has entered the detection target object S is reflected or scattered in the detection target object S and travels to the side of the detection target object S is also conceivable. Even in such a case, because the illumination light can be blocked by the color filters302, it is possible to prevent the illumination light from being detected by the light detection unit21.

Moreover, the color filters302may have different transmission wavelengths for the regions opposed to the detection target objects S. Accordingly, in the case where the detection target light generated from the adjacent detection target objects S has different wavelengths, it is possible to block the detection target light from the adjacent detection target objects S and to prevent cross talk from occurring.

Furthermore, by forming one adsorption region4a1so as to be opposed to a plurality of light detection units21and providing the color filters302having different colors to the light detection units21, it is possible to confirm the properties of light emission spectrum of the detection target light in the detection target object S in one adsorption region4a1.FIG. 23andFIG. 24are each a graph showing an example of the light emission spectrum of the detection target light and light transmittance of the color filter302.

FIG. 23(a)andFIG. 24(a)each show a transmission wavelength (C1) in the case where the color filters302have one color, andFIGS. 23(b)andFIG. 24(b)each show transmission wavelengths (C1, C2, and C3) in the case where the color filters302have 3 colors. As shown inFIG. 23(b)andFIG. 24(b), in the case where the detection target light includes a plurality of wavelength components, the difference can be discriminated.

The on-chip lenses303collects the incident detection target light on the light detection unit21. The on-chip lenses303may have a hemispherical shape in which the side of the detection target object S is spherical, and may have a lens shape different from this. Moreover, the respective on-chip lenses303may be provided to be opposed to the light detection unit21. With the on-chip lenses303, it is possible to collect the detection target light isotropically emitted from the detection target object S on the light detection unit21and to improve the detection accuracy of the detection target light.

The chemical sensor301is configured as described above. It should be noted that either one of the color filters302and the on-chip lenses303may be provided.

A method of manufacturing the chemical sensor301will be described.FIG. 19andFIG. 20are each a schematic diagram showing a method of manufacturing the chemical sensor301.

As shown inFIG. 19(a), the light detection unit21is formed on the substrate2and the protective insulating film22is formed thereon, in the same way as that in the first embodiment. The protective insulating film22is formed to have a film thickness adjusted so that the on-chip lens303is focused on the light detection unit21, taking into account of the focal length of the on-chip lens303.

Next, as shown inFIG. 19(b), the color filters302are formed on the protective insulating film22. The color filters302are formed by spin coating, for example. Furthermore, as shown inFIG. 19(c), the on-chip lenses303are formed on the color filters302. The on-chip lenses303can be formed by a melt flow method.

Specifically, a lens material, e.g., silicon nitride, is deposited on the color filters302, and a resist pattern having an island shape is formed thereon. Next, the resist pattern is fluidized by heat treatment, and the resist pattern is molded into a convex lens shape using surface tension. By etching the resist pattern and the lens material from its upside, the lens shape of the resist pattern is transferred to the lens material and the lens material can be processed into a lens shape.

Next, as shown inFIG. 20(a), the low refractive index layer3is laminated so that the on-chip lenses303are embedded. The low refractive index layer3can be formed by a spin coating method. For example, in the case where fluorine-containing polysiloxane resin (refractive index n1=1.42) is used as the material of the low refractive index layer3, this resin is dissolved in propylen glycol monomethyl ether acetate (PEGMEA) being a solvent. The saturated solubility of fluorine-containing polysiloxane resin in PEGMEA is small, and the solution has extremely low viscosity. However, here, it is only necessary that the on-chip lenses303having a lens shape are embedded and the surface is flat. For example, the solution is applied such that the film thickness is about 1 μm from the top of the on-chip lens303. By using the solution having low viscosity as described above, it is possible to improve the embeddability of the on-chip lenses303and to prevent a void (cavity) from being formed.

After that, a solvent in the solution is dried and removed by heat treatment at 120° C. for 1 minute, and the fluorine-containing polysiloxane resin is sufficiently cured by heat treatment at 230° C. for 5 minutes. In this way, the on-chip lenses303having a lens shape are embedded, and the low refractive index layer3whose surface is molded into flat can be formed.

Next, as shown inFIG. 20(b), the high refractive index layer4is laminated on the low refractive index layer3. The high refractive index layer4can be laminated by a spin coating method, for example. It should be noted that the high refractive index layer4can be formed also by printing, applying a resin sheet, or applying a plate-like member.

In this way, the chemical sensor301can be manufactured. By joining the light introduction unit6to the chemical sensor301in the same way as that in the first embodiment, the chemical sensor module can be obtained.

Fourth Embodiment

A chemical sensor according to a fourth embodiment of the present technology will be described. It should be noted that in this embodiment, the same configurations as those of the chemical sensor according to the first embodiment will be denoted by the same reference symbols and a description thereof will be omitted. The chemical sensor according to this embodiment is obtained by adding light blocking walls to the layered structure of the chemical sensor according to the first embodiment.

FIG. 21is a cross-sectional view showing the configuration of a chemical sensor401according to this embodiment. As shown in the figure, the chemical sensor401includes light blocking walls402in addition to the substrate2, the low refractive index layer3, and the high refractive index layer4. The light blocking walls402are formed in the low refractive index layer3in a direction perpendicular to the layer.

The light blocking walls402block the detection target light from the adjacent detection target objects S. The light blocking walls402are formed of a material that is capable of blocking at least the wavelength of the detection target light, and can be arranged such that the low refractive index layer3is partitioned into areas opposed to the light detection units21. In addition, the light blocking walls402can be provided for every a plurality of light detection units21.

The light blocking walls402can be formed by laminating the low refractive index layer3before patterning the low refractive index layer3, and filling a material. In addition, other than that, the low refractive index layer3can be formed by forming the light blocking walls402on the substrate2in advance and filling a material therein.

With the light blocking walls402, the detection target light that has entered from the adjacent detection target object S is blocked, i.e., it is possible to prevent the cross talk of the light detection unit21from occurring. In the case where the light blocking walls402are formed in the high refractive index layer4, the illumination light that propagates in the high refractive index layer4is blocked. However, by forming the light blocking walls402in the low refractive index layer3, it is possible to introduce the illumination light without hindering the propagation of the illumination light.

It should be noted that the light blocking walls402may be added to the chemical sensor described in the third embodiment. In this case, the light blocking walls402can be arranged such that the on-chip lenses303are partitioned. In addition to the light collection with the on-chip lenses303, it is possible to further prevent cross talk from occurring.

The present technology is not limited to the above-mentioned embodiments and various modifications can be made without departing from the gist of the present technology.

It should be noted that the present technology may also take the following configurations.

a substrate;

a low refractive index layer that is laminated on the substrate and has a second refractive index smaller than a first refractive index that is a refractive index of a detection target object;

a high refractive index layer in which illumination light propagates, which is laminated on the low refractive index layer, has a third refractive index larger than the first refractive index, and includes a holding surface on which the detection target object is held; and

a light detection unit that is provided on the substrate and detects detection target light generated from the detection target object by the illumination light.

(2) The chemical sensor according to (1) above, in which

the holding surface has adsorption regions to which the detection target object is adsorbed and non-adsorption regions to which the detection target object is not adsorbed.

(3) The chemical sensor according to (1) or (2) above, in which

the adsorption regions are separated by the non-adsorption regions.

(4) The chemical sensor according to any one of (1) to (3) above, in which

the light detection unit includes a plurality of light detection units, and the adsorption regions are opposed to the plurality of light detection units, respectively.

(5) The chemical sensor according to any one of (1) to (4) above, in which

the light detection unit includes a plurality of light detection units, and the adsorption regions are opposed to the plurality of respective light detection units, respectively.

(6) The chemical sensor according to any one of (1) to (5) above, in which

the adsorption regions are formed in such a way that an area thereof is increased along a direction in which the illumination light propagates.

(7) The chemical sensor according to any one of (1) to (6) above, in which

the adsorption regions are formed by hydrophilic processing applied to the holding surface, and

the non-adsorption regions are formed by hydrophobic processing applied to the holding surface.

(8) The chemical sensor according to any one of (1) to (7) above, in which

the adsorption regions are formed by hydrophobic processing applied to the holding surface, and the non-adsorption regions are formed by hydrophilic processing applied to the holding surface.

(9) The chemical sensor according to any one of (1) to (8) above, in which

the non-adsorption regions are covered by a coating film to which the detection target object is not adsorbed, and

the adsorption regions are not covered by the coating film.

(10) The chemical sensor according to any one of (1) to (9) above, in which

the coating film has light reflectivity.

(11) The chemical sensor according to any one of (1) to (10) above, further including

a color filter that is provided between the light detection unit and the low refractive index layer, and blocks wavelengths other than that of the detection target light.

(12) The chemical sensor according to any one of (1) to (11) above, further including

an on-chip lens that is provided between the light detection unit and the low refractive index layer, and collects the detection target light on the light detection units.

(13) The chemical sensor according to any one of (1) to (12) above, further including

light blocking walls that are provided on the low refractive index layer and partition the low refractive index layer into areas opposed to the respective light detection units.

(14) The chemical sensor according to any one of (1) to (13) above, in which

the illumination light is excitation light, and

the detection target light is fluorescent light.

a chemical sensor includinga substrate,a low refractive index layer that is laminated on the substrate and has a second refractive index smaller than a first refractive index that is a refractive index of a detection target object,a high refractive index layer in which illumination light propagates, which is laminated on the low refractive index layer, has a third refractive index larger than the first refractive index, and includes a holding surface on which the detection target object is held, anda light detection unit that is provided on the substrate and detects detection target light generated from the detection target object by the illumination light; and

a light introduction unit that is joined to the chemical sensor and introduces the illumination light into the high refractive index layer.

a chemical sensor module includinga chemical sensor includinga substrate,a low refractive index layer that is laminated on the substrate and has a second refractive index smaller than a first refractive index that is a refractive index of a detection target object,a high refractive index layer in which illumination light propagates, which is laminated on the low refractive index layer, has a third refractive index larger than the first refractive index, and includes a holding surface on which the detection target object is held, anda light detection unit that is provided on the substrate and detects detection target light generated from the detection target object by the illumination light, anda light introduction unit that is joined to the chemical sensor and introduces the illumination light into the high refractive index layer; and

a light source that applies the illumination light to the light introduction unit.

preparing a chemical sensor includinga substrate,a low refractive index layer that is laminated on the substrate and has a second refractive index smaller than a first refractive index that is a refractive index of a detection target object,a high refractive index layer in which illumination light propagates, which is laminated on the low refractive index layer, has a third refractive index larger than the first refractive index, and includes a holding surface on which the detection target object is held, anda light detection unit that is provided on the substrate and detects detection target light generated from the detection target object by the illumination light;

introducing, by a light introduction unit, the illumination light into the high refractive index layer; and

detecting, by the light detection unit, the detection target light.

DESCRIPTION OF REFERENCE NUMERALS