JP7097563B2 - Target substance detection device and target substance detection method - Google Patents

Description

The present invention relates to a target substance detection device and a target substance detection method capable of optically detecting a target substance existing in a liquid by utilizing an evanescent field generated by total internal reflection of light.

In recent years, methods for detecting and quantifying minute substances existing in a solution, particularly biological substances such as DNA, RNA, proteins, viruses, and bacteria, have been developed. As such a method, for example, a method using an evanescent field by total reflection is known.
As a method of utilizing the evanescent field by total reflection, for example, a total reflection illumination fluorescence microscope can be mentioned. The total reflection illumination fluorescence microscope totally reflects the incident light at the interface between the liquid sample and the cover glass or the slide glass, and uses the generated evanescent field as the excitation light to observe fluorescence with less background light that causes noise. This is a technique to be performed (see Patent Document 1). Further, the technique is a technique capable of realizing super-resolution and enables single molecule observation.

Regarding the method using total reflection, magnetic particles that bind to the target substance are used, and a bond between the target substance and the magnetic particles is formed on the surface of the detection chip by applying a magnetic field based on a magnet arranged under the detection chip. A method has been proposed in which the target substance is detected by attracting the local region to the local region and irradiating the local region with the excitation light (see Patent Document 2). According to this proposal, the application of a magnetic field promotes the adsorption or proximity of the target substance to the surface of the detection chip, and measurement can be performed in a short time.
However, in this proposal, since the optical prism is present under the detection chip, the distance between the local region and the magnet cannot be sufficiently made, and the strength of the magnetic field applied by the magnet cannot be sufficiently reduced. However, there is a problem that the target substance cannot be sufficiently attracted to the local region because the target substance is attenuated by the time it reaches the surface of the detection chip.
Further, if an attempt is made to apply a strong magnetic field in order to solve this problem, the device becomes large and the manufacturing cost increases.

As a fluorescence detection method using the magnetic particles, by comparing and observing the state before and after the application of the magnetic field by the magnetic field application unit (for example, a magnet), the detection excluding the noise signal from the optical signals before the application of the magnetic field can be detected. A method for doing so has been proposed (see Non-Patent Documents 1 and 2). According to this proposal, the target substance bonded to the magnetic particles moves due to the application of the magnetic field, whereas the noise generated in the scratches on the surface of the detection chip does not move due to the application of the magnetic field. The noise signal can be eliminated by performing the detection focusing on the optical signal.
However, since the optical prism is also used in the method of comparatively observing the state before and after the application of the magnetic field, it is difficult to move the target substance due to the attenuation of the strength of the magnetic field, and the strength of the magnetic field is increased. If this is the case, the equipment will become large and the manufacturing cost will increase.

Japanese Patent Application Laid-Open No. 2002-236258 Japanese Patent No. 5301894

Masato Yasuura, Makoto Fujimaki "Development of Waveguide Mode Image Sensor for Trace Detection" Materials of the Institute of Electrical Engineers of Japan, Sensors and Micromachines Division General Study Group (June 29, 30, 2016), pp. 45-52, Institute of Electrical Engineers of Japan (2016) M. Yasuura and M. Fujimaki, Sci. Rep. Vol. 6, pp. 39241-1-39241-7 (2016)

The present invention uses a target substance detection device and a target substance detection device that can be used for detecting a target substance using magnetic particles by solving the above-mentioned problems in the prior art, and can be manufactured in a small size and at low cost. It is an object to provide a method for detecting a target substance.

The means for solving the above problems are as follows. That is,
<1> With respect to the detection surface arranged on the surface on the upper surface side with respect to the bottom surface, the upwardly inclined surface inclined in the direction away from the detection surface as the upper surface toward the bottom surface side with respect to the thickness direction, and the thickness direction. An overall schematic plate having one of the inclined surfaces of the downward inclined surface that inclines in a direction away from the detection surface as it goes from the bottom surface to the upper surface side, and a main body portion that receives light and can guide light inside. A second type of light-transmitting member having a shape, the light-transmitting member is irradiated from the upper surface side and passed through the upwardly inclined surface, and the light is incident on the detection surface via the main body under full reflection conditions. One of the light incident structure 1 and the second light incident structure in which the light emitted from the upper surface side and reflected by the downward inclined surface is incident on the detection surface via the main body under all reflection conditions. A detection chip having a light incident structure, a light irradiation unit arranged on the upper surface side of the light transmissive member, and a light irradiation unit capable of irradiating the detection surface with the light under all reflection conditions via the light incident structure. A magnetic field application portion arranged on the bottom surface side of the light transmissive member and a region located on the detection surface and near the surface of the detection surface are defined as a detection region, and the target substance and magnetic particles are irradiated with the light. A V-shaped cross section comprising a light detection unit capable of detecting an optical signal emitted from a coupled body including The object material is characterized by having at least one notch of the bottom surface side notch having a V-shaped cross section formed on the upper surface side notch portion and the bottom surface and having the downward inclined surface. Detection device.
<2> The target substance detection device according to <1>, wherein a low-refractive index material having a refractive index lower than that of the main body is embedded in the notch.
<3> After the light incident structure reflects at least one of the light passed through the upward inclined surface in the first light incident structure and the light reflected on the downward inclined surface in the second light incident structure on the bottom surface. The target substance detection device according to any one of <1> to <2>, which is capable of incident on the detection surface under total reflection conditions.
<4> The target substance according to any one of <1> to <3>, wherein the shortest distance between the light incident position on the inclined surface and the light irradiation position on the detection surface is 1.0 mm to 50.0 mm. Detection device.
<5> The target substance detection device according to any one of <1> to <4>, wherein the thickness of the light transmissive member is 0.1 mm to 10.0 mm.
<6> The target substance detection device according to any one of <1> to <5>, wherein a liquid sample storage groove having at least a part as a detection surface is formed on the upper surface of the light transmissive member.
<7> The target substance detection according to <6>, wherein the liquid sample storage groove has an inclined detection surface as a detection surface, which is inclined in a direction away from the inclined surface from the upper surface toward the bottom surface in the thickness direction of the light transmissive member. Device.
<8> The above <1>, in which a part of the upper surface of the light transmissive member is used as a detection surface and a side wall portion is erected around the detection surface so as to form a box-shaped body having the detection surface as the bottom. > To the target substance detection device according to any one of <5>.
<9> The target substance detection method using the target substance detection device according to any one of <1> to <8>, from the upper surface side of the light transmissive member to the detection surface via the light incident structure. A light irradiation step of irradiating light under reflection conditions, a magnetic field application step of applying a magnetic field from the bottom surface side of the light transmissive member, and light emitted from a conjugate containing a target substance and magnetic particles due to the light irradiation. A method for detecting a target substance, which comprises an optical detection step for detecting a signal.

According to the present invention, a target substance detection device that can solve the above-mentioned problems in the prior art, can be used for detecting a target substance using magnetic particles, and can be manufactured in a small size and at low cost, and the object thereof. It is possible to provide a target substance detection method using a substance detection device.

It is explanatory drawing explaining the outline of the target substance detection apparatus which concerns on 1st Embodiment. It is explanatory drawing explaining the outline of the target substance detection apparatus which concerns on 2nd Embodiment. It is explanatory drawing (1) which shows an example of the incident angle of light. It is explanatory drawing (2) which shows an example of the incident angle of light. It is explanatory drawing (3) which shows an example of the incident angle of light. It is explanatory drawing explaining the outline of the target substance detection apparatus which concerns on 3rd Embodiment. It is explanatory drawing explaining the outline of the target substance detection apparatus which concerns on 4th Embodiment. It is explanatory drawing explaining the outline of the target substance detection apparatus which concerns on 5th Embodiment. It is explanatory drawing (1) which shows the modification. It is explanatory drawing (2) which shows the modification. It is explanatory drawing explaining the outline of the target substance detection apparatus which concerns on 6th Embodiment. It is explanatory drawing explaining the outline of the target substance detection apparatus which concerns on 7th Embodiment.

(Target substance detector)
The target substance detection device of the present invention has a detection chip, a light irradiation unit, a magnetic field application unit, and further includes a light detection unit, if necessary.

<Detection chip>
The detection chip includes a light transmissive member described below.

-Light transmissive member-
The light transmissive member includes a detection surface arranged on a surface on the upper surface side with respect to the bottom surface, an upwardly inclined surface that inclines in a direction away from the detection surface as the upper surface toward the bottom surface side in the thickness direction, and the above. One of the inclined surfaces of the downward inclined surface that inclines in the direction away from the detection surface as it goes from the bottom surface to the upper surface side in the thickness direction, and the main body portion that receives light and can guide the inside. It is a member having a substantially plate-like shape as a whole.
Further, the light transmissive member has a first light incident structure in which the light irradiated from the upper surface side and passed through the upward inclined surface is incident on the detection surface via the main body portion under total reflection conditions. It has one of the light incident structures of the second light incident structure in which the light irradiated from the upper surface side and reflected by the downward inclined surface is incident on the detection surface via the main body under the total reflection condition. It is composed of.
In the light transmissive member, it is preferable that the surface on which the light acts, that is, the surface on which the light is incident and the surface on which the light is reflected is optically smooth.

The light transmissive member has both a role of an optical prism in a conventional detection chip and a role of forming an evanescent field based on total reflection of light on the detection surface, and a setting position of the detection surface in the detection chip. Since the magnetic field application portion can be arranged on the lower side, it has a role of guiding the light emitted from the upper surface side of the light transmissive member to the detection surface.
That is, the light transmissive member is characterized by having the light incident structure in which the light emitted from the upper surface side is incident on the detection surface under total reflection conditions.

The material for forming the light-transmitting member is not particularly limited and may be appropriately selected depending on the intended purpose. However, plastic materials such as polystyrene, polycarbonate, cycloolefin and acrylic that can be mass-produced by injection molding and high transparency A glass material such as silica glass is preferable. The polystyrene and the cycloolefin have less autofluorescence and can reduce noise, and the polycarbonate can realize a high refractive index, so that the size can be reduced. Further, since the acrylic has high transparency, it is possible to suppress the attenuation of light at the time of guiding light.
The thickness of the light transmissive member is not particularly limited, but is preferably 0.1 mm to 10.0 mm from the viewpoint of rigidity, light guide performance, and degree of magnetic attenuation. If the thickness is less than 0.1 mm, cracks, distortions, etc. are likely to occur and handling may be difficult. Further, if the thickness is smaller than the beam diameter of the incident light, light loss occurs at the time of incident and noise light is generated. Therefore, the thickness is preferably larger than the beam diameter. Further, since the magnetic field is applied from the bottom surface side, if the thickness exceeds 10.0 mm, it may be difficult to apply a suitable magnetic field on the detection surface due to attenuation. Further, when the thickness is 5.0 mm or less, the attenuation of the magnetic field can be greatly suppressed.

As the light transmissive member, a liquid sample whose presence or absence of the target substance is verified is introduced into the region where the detection surface is formed. The configuration for holding the liquid sample to be introduced is not particularly limited, but it is preferable to apply the following configuration.
That is, as one configuration, a side wall portion stands around the detection surface so that a part of the upper surface of the light transmissive member serves as the detection surface and forms a box-shaped body having the detection surface as the bottom. The configuration to be set is mentioned. In this configuration, the liquid sample is held in the box. The side wall portion can be formed, for example, by using the same material and forming method as the light transmissive member.
Further, as another configuration, there is a configuration in which a liquid sample storage groove having at least a part thereof as the detection surface is formed on the upper surface of the light transmissive member. In this configuration, the liquid sample is held in the liquid sample storage groove. The liquid sample storage groove may be formed by a molding process at the time of forming the plate-shaped member constituting the light transmissive member, or may be formed by a cutting process after the plate-shaped member is formed.
Further, as yet another configuration, the liquid sample storage groove is bored from the side surface of the light transmissive member on the side opposite to the side surface on which the inclined surface is formed toward the inclined surface side. Examples thereof include a configuration formed as a groove. In this configuration, among the surfaces constituting the liquid sample storage groove (drilling groove), the surface facing the bottom surface at the position closest to the bottom surface constitutes the detection surface.
In order to prevent the liquid sample from spilling from the liquid sample storage groove, the opening of the liquid sample storage groove can be sealed with a cover glass or the like, if necessary.

When forming the liquid sample storage groove, any shape such as concave, V-shaped, trapezoidal or the like can be applied as the shape of the groove in a cross-sectional view, but a flat surface such as a semicircle is formed. If the shape is not present, the detection surface cannot be formed, so such a shape is excluded.
The liquid sample storage groove is not particularly limited, but as the detection surface, an inclined detection surface that inclines in a direction away from the inclined surface toward the bottom surface side from the upper surface in the thickness direction of the light transmissive member. It may be configured to have. That is, when such an inclined detection surface is provided as the detection surface, the incident angle of the light with respect to the inclined surface set to irradiate the detection surface with the light propagating in the main body under the total reflection condition is set. It can be set in a wide range, and the degree of freedom of setting can be expanded.

The detection chip is irradiated with the light from the light irradiation unit arranged on the upper surface side of the light transmissive member from the viewpoint of avoiding competition with the magnetic field application portion arranged on the bottom surface side of the light transmissive member. It is assumed that it will be done.
That is, in the light incident structure, the light can be incident on the detection surface under the total reflection condition by changing the traveling direction of the light emitted from the upper surface side of the light transmissive member by the inclined surface. And.
The inclined surface may be formed as a side surface of the light transmitting member as long as it plays such a role, and a notch formed on at least one of the upper surface and the bottom surface of the light transmitting member. It may be formed as a constituent surface of the portion.

The notch is formed on the upper surface of the light transmissive member and has an upward inclined surface on the upper surface side, and is formed on the bottom surface of the light transmissive member and has a downward inclined surface. It is formed as at least one of the side notches. The cutout portion may be formed by a molding process at the time of forming the plate-shaped member constituting the light transmissive member, or may be formed by a cutting process after the plate-shaped member is formed.

Further, as the notch portion on the upper surface side, the notched portion may be a void, but since it is difficult to clean the notched portion when the liquid sample invades this portion, the refractive index is lower than that of the main body portion. A refracting material may be embedded. That is, when the upper surface side notch is embedded in the low refraction material, it is possible to prevent the liquid sample from invading the upper surface side notch.
Further, since the low refraction material is used, the light can be guided to the detection surface by utilizing the refraction at the interface between the upward inclined surface of the notch on the upper surface side and the main body portion.
When the low refractive index material is embedded in the notch on the upper surface side, for example, a known plastic material having a refractive index of about 1.4 is embedded in the notch on the upper surface side, and the main body portion has a refractive index. The light transmissive member can be formed by forming it from a known plastic material of about 1.6.

Further, since the bottom surface side notch portion is formed on the bottom surface of the light transmissive member, the liquid sample introduced to the top surface side does not invade the notched portion.
However, from the viewpoint of preventing the downwardly inclined surface of the bottom surface side notch portion from being exposed to the outside and becoming dirty due to adhesion of dust or the like in the atmosphere, the notch portion is the same as the top surface side notch portion. It is preferable to embed a low refraction material.

By the way, when the distance between the light incident position on the inclined surface and the light irradiation position on the detection surface (the set position of the detection surface on the upper surface side) is long, the light traveling in the main body portion is weakened. Further, each time the light is reflected by the main body, the light is weakened. On the other hand, if the distance between the light incident position and the light irradiation position on the detection surface is too close, noise due to scattering or the like generated at the time of incident is mixed in the optical signal, which causes a decrease in detection accuracy.
Therefore, there is a suitable range for the distance between the light incident position on the inclined surface and the light irradiation position on the detection surface, and specifically, the shortest distance is 1.0 mm to 50.0 mm. Is preferable.
With such a distance, it is possible to suppress the weakening of the light traveling in the main body, suppress noise, and reduce the number of times the light is reflected by the main body, which is optimal. , The number of times can be set to be one. Further, even when the inclined surface is formed as the downward inclined surface, it is preferable to reduce the number of times the light is reflected by the main body portion, and the number of times the light is reflected by the main body portion is set to zero and the downward direction is set. It is optimally set so that the light is incident on the detection surface with only one reflection on the inclined surface.
In addition, in this specification, "light transmittance" means that the visible light transmittance is 0.5% or more.

<Coating layer>
As the light transmissive member, a coating layer may be formed on the detection surface.
The material for forming the coating layer is not particularly limited as long as it has light transmission as in the case of the light transmitting member, and examples thereof include known resin materials and glass materials.
The method for forming the coating layer is not particularly limited, and examples thereof include known methods such as a sputtering method, a vapor deposition method, a spin coating method, coating, pasting, and laminating.
The coating layer is formed so as to cover the detection surface of the light transmissive member, and the upper surface of the coating layer serves as the detection surface.
According to this coating layer, when the light-transmitting member is made of a relatively soft resin, the detection surface of the light-transmitting member is scratched by coating with a hard resin or a glass material which is hard to be scratched. It can be prevented from sticking.
Further, when the coating layer is formed of a fluororesin or the like, an antifouling effect for preventing the detection surface from becoming dirty can also be obtained. In addition, due to this antifouling effect, it is possible to prevent the target substance and magnetic particles from adsorbing on the upper surface of the coating layer, and by extension, the target substance bonded to the magnetic particles by a magnetic field application portion described later. When the magnetic particles and the target substance are adsorbed on the surface of the coating layer and are detected, it is possible to prevent the magnetic particles from adhering to the surface of the coating layer and not moving.
Further, when the processing accuracy of the light transmissive member is poor and the detection surface is roughened, the coating layer alleviates the roughness of the detection surface and suppresses light scattering during total reflection. , Noise can be reduced. In this case, although there is no particular limitation, it is particularly preferable to select a thin glass film as the coating layer and laminate it on the detection surface of the light transmissive member from the viewpoint of obtaining the detection surface having excellent smoothness.
Further, when the coating layer made of glass is formed on the detection surface of the light transmissive member made of resin, it is possible to obtain a detection chip having high chemical resistance and resistance to organic solvents, strong acids and strong alkalis.

The light incident structure includes an inclination angle of the inclined surface, an irradiation angle of the light with respect to the inclined surface, a material (refractive index) of the light transmissive member, a light incident position on the inclined surface, and the detection surface. A known optical calculation method for a path of the light emitted from the upper surface side of the light transmissive member to the detection surface by giving conditions such as a distance from the light irradiation position and the thickness of the light transmissive member. It can be set by calculating with.

<Light irradiation part>
The light irradiation unit is a unit arranged on the upper surface side of the light transmissive member and capable of irradiating the detection surface with the light under total reflection conditions via the light incident structure of the light transmissive member. ..

The light source of the light irradiation unit is not particularly limited and may be appropriately selected depending on the intended purpose, and examples thereof include known lamps, LEDs, and lasers. In the target substance detection device, the detection surface is irradiated with the light under the total reflection conditions to form the evanescent field in the vicinity of the surface of the detection surface, and the combination containing the target substance and magnetic particles is formed. The detection principle is to generate an optical signal. Therefore, the role required of the light irradiation unit is only to irradiate the detection surface with the light under the total reflection conditions, and there is no limitation on the selection of the light source as long as it plays such a role.

When a radiation light source such as a lamp or an LED is used, the irradiation light may be incident on the light incident portion by using a guide portion such as a collimating lens that regulates the irradiation direction of the irradiation light to a specific direction. can.
Further, as the light incident on the light incident portion, monochromatic light having a wavelength capable of exciting fluorescence or light from a light source having a wide wavelength band such as a lamp or an LED is used for the conjugate. It is preferable that the light is transmitted through an optical filter such as a bandpass filter to make it monochromatic, and the light has only a wavelength that can excite the fluorescence.

<Magnetic field application part>
The magnetic field application portion is a portion arranged on the bottom surface side of the light transmissive member.
The magnetic field application portion is not particularly limited, but is arranged directly below the bottom surface of the light transmissive member at a position facing the detection surface of the detection chip in the thickness direction from the viewpoint of exerting a strong magnetic field on the liquid sample. Is preferable.

The constituent member of the magnetic field application portion is not particularly limited as long as the magnetic field can be applied to the region where the liquid sample is introduced, and known permanent magnets, electromagnets, and the like can be mentioned.

Known magnetic particles such as magnetic beads are added to the liquid sample, and when the target substance is present, a bond between the target substance and the magnetic particles is formed. When the target substance is a substance that does not easily generate fluorescence, a fluorescent labeling substance that specifically adsorbs or binds to the target substance to label the target substance may be used. As the fluorescent labeling substance, for example, a known fluorescent substance such as a fluorescent dye, a quantum dot, or a fluorescent dye can be used.
Further, as a method for detecting the target substance, in addition to fluorescence detection, there is also a method of detecting scattered light emitted from the conjugate by receiving the evanescent light in the evanescent field.
When detecting the scattered light, if the target substance is a substance that does not easily generate scattered light, a light scattering substance that specifically adsorbs or combines with the target substance and scatters the light may be used. Examples of the light scattering substance include nanoparticles such as polystyrene beads and gold nanoparticles.
The method for binding the target substance, the magnetic particles, the fluorescent labeling substance, and the light scattering substance is not particularly limited, and depending on the substance, physical adsorption, antigen-antibody reaction, DNA hybridization, biotin-avidin. Known binding methods such as binding, chelate binding, and amino binding can be applied.

Since light from the target substance or the like is generated in the evanescent field formed near the surface of the detection surface, the conjugate floating in the liquid sample is required to detect the optical signal in a short time. It is necessary to draw the light to the vicinity of the surface of the detection surface.
In the magnetic field application unit, the magnetic field is applied to attract the conjugate floating in the liquid sample to the surface of the detection surface, enabling detection in a short time.

By the way, in the detection, in order to perform detection excluding noise caused by scratches or the like on the detection surface, the state before and after the movement of the coupled body accompanied by the application of the magnetic field by the magnetic field application portion is compared and observed. , The detection may be performed excluding the noise signal included in the optical signal before the movement of the conjugate. According to such detection, the target substance bonded to the magnetic particles moves by the magnetic field application portion, whereas noise generated in scratches or the like on the detection surface does not move by the magnetic field application portion. The noise signal can be eliminated by performing detection focusing on the moving optical signal.
In the case of performing such detection, the magnetic field applying portion of the detection surface on the bottom surface side of the light transmissive member in a state where the magnetic field is applied in order to compare and observe the state before and after the movement of the coupled body. It is a member that can move in a direction having a vector component in a direction parallel to the in-plane direction, and can be composed of, for example, a permanent magnet or the like and a slide member that can slide and move while supporting the permanent magnet or the like. ..

<Light detector>
The photodetector is arranged on the detection surface, has a region near the surface of the detection surface as a detection region, and can detect an optical signal emitted from the conjugate containing the target substance upon irradiation with the light. Will be done.
The photodetector is not particularly limited and may be appropriately selected depending on the intended purpose. Known photodetectors such as known photodiodes and photomultiplier tubes, CCD image sensors, CMOS image sensors and the like are known. Imaging device can be used.

(Target substance detection method)
The target substance detection method of the present invention is a method of detecting a target substance using the target substance detection device of the present invention, and includes at least a light irradiation step and a magnetic field application step, and further, if necessary, Includes a light detection step.

<Light irradiation process>
The light irradiation step is a step of irradiating the detection surface with light from the upper surface side of the light transmissive member via the light incident structure of the light transmissive member under total reflection conditions.
As the method for carrying out the light irradiation step, the matters described for the light irradiation unit in the target substance detection device of the present invention can be applied, so duplicate description will be omitted.

<Magnetic field application process>
The magnetic field application step is a step of applying a magnetic field from the bottom surface side of the light transmissive member by the magnetic field application portion, and preferably, the magnetic field application portion is placed in the plane of the detection surface in a state where the magnetic field is applied. This is a process of moving in a direction having a vector component parallel to the direction.
As the method for carrying out the magnetic field application step, the matters described for the magnetic field application unit in the target substance detection device of the present invention can be applied, so duplicate description will be omitted.

<Light detection process>
The light detection step is a step of detecting an optical signal emitted from the conjugate in connection with the irradiation of the light.
As the method for carrying out the light detection step, the matters described for the photodetector in the target substance detection device of the present invention can be applied, so duplicate description will be omitted.

Regarding the target substance detection device and the target substance detection method according to the present invention, the positional relationship was explained based on the positional relationships of the "top surface", "bottom surface", and "side surface" of the light transmissive member. However, these positional relationships indicate relative positional relationships, and even when the target substance detection device is used upside down or tilted, there is no change in the relative positional relationships. Is included in the technical scope of the present invention. For example, even when the target substance detection device is used at an angle of 90 ° and the "top surface" and "bottom surface" are located laterally and the "side surface" is located above or below, the magnetic field application portion is arranged. If there is no change in the relative positional relationship between the "top surface" and the "side surface" when the surface of the light transmissive member on the side is viewed as the "bottom surface", it is included in the technical scope of the present invention ( For example, see the seventh embodiment described later, FIG. 12).

[First Embodiment]
Hereinafter, a configuration example of the target substance detection device of the present invention will be specifically described with reference to the drawings.
First, the target substance detection device according to the first embodiment will be described with reference to FIG. Note that FIG. 1 is an explanatory diagram illustrating an outline of the target substance detection device according to the first embodiment.

As shown in FIG. 1, the detection chip 1 in the first embodiment has a light transmitting member 2. The light transmissive member 2 is a plate-shaped member, a part of the upper surface is a detection surface 2a, the side surface is an upward inclined surface 2b, and the body portion receives light from the upper surface and can guide the inside. The main body is 2c. Here, the detection surface 2a is a surface set on a part of the upper surface of the light transmissive member 2, and when the back surface (the bottom surface side of the light transmissive member 2) is irradiated with light under total reflection conditions. , An evanescent field is formed near the surface (upper surface side of the light transmissive member 2).
Further, on the upper surface of the light transmissive member 2, a side wall portion 4 is erected around the detection surface 2a so as to form a box-shaped body having the detection surface 2a as the bottom, and the liquid sample A is placed in the box-shaped body. be introduced.

Here, the upward inclined surface 2b configured as the side surface of the light transmitting member 2 is a surface inclined in a direction away from the detection surface 2a from the upper surface to the bottom surface side with respect to the thickness direction Y of the light transmitting member 2. In the main body 2c, the light emitted from the light irradiation unit B arranged to face the upward inclined surface 2b is inclined with respect to the length direction X orthogonal to the thickness direction Y of the light transmissive member 2. Being incident.
The light incident on the main body 2c is reflected a plurality of times on the upper surface and the bottom surface of the main body 2c and propagates in the main body 2c along the length direction X.
The light propagating in the main body 2c is totally reflected at the position of the detection surface 2a to form an evanescent field near the surface of the detection surface 2a (first light incident structure).

When the target substance detection device is configured by using the detection chip 1, as shown in FIG. 1, the light irradiation unit B faces the upward inclined surface 2b on the side surface of the light transmissive member 2 on the upper surface side of the light transmissive member 2. The magnetic field application unit C is arranged directly below the bottom surface of the light transmissive member 2 at a position facing the detection surface 2a in the thickness direction Y, and the light detection unit D is arranged on the upper surface side of the light transmissive member 2. Will be done.
In the magnetic field application unit C, the application of the magnetic field attracts the conjugate containing the target substance and the magnetic particles suspended in the liquid sample A to the vicinity of the surface of the detection surface 2a on which the conjugate can emit an optical signal. Enables measurement in a short time. Further, by sliding the magnetic field application unit C, for example, in the length direction X and detecting the optical signals before and after the slide movement, it is possible to detect only the coupled body that follows the slide movement of the magnetic field application unit C, and the detection is possible. It is possible to perform detection excluding noise signals caused by scratches or the like on the surface 2a.
Further, the photodetection unit D can detect the light from the conjugate in the vicinity of the surface of the detection surface 2a.

In the target substance detection device according to the first embodiment configured as described above, the magnetic field application unit C is placed on the bottom surface of the light transmissive member 2 without competing for the arrangement positions of the light irradiation unit B and the magnetic field application unit C. Since it can be arranged at a position close to the detection surface 2a and the light emitted from the light irradiation unit B can be irradiated to the detection surface 2a under all reflection conditions, it is separated from the detection surface 2a. It is not necessary to use a strong magnetic field applying member capable of applying a magnetic field from a vertical position, it is possible to avoid a large-scale device, and it can be manufactured in a small size and at low cost.

[Second Embodiment]
Next, the target substance detection device according to the second embodiment will be described with reference to FIG. Note that FIG. 2 is an explanatory diagram illustrating an outline of the target substance detection device according to the second embodiment.

As shown in FIG. 2, the detection chip 10 in the second embodiment has a light transmitting member 12. In the light transmitting member 12, unlike the light transmitting member 2 in the first embodiment, a liquid sample storage groove 14 for introducing the liquid sample A is formed on the upper surface thereof. The liquid sample storage groove 14 is formed in a concave cross section, and the bottom surface thereof is a detection surface 12a.
Further, unlike the light transmitting member 2 in the first embodiment, the light transmitting member 12 is formed on the upper surface and has an upper surface side notch portion 15 having an upward inclined surface 12b. The notch portion 15 on the upper surface side is formed in a shape having a substantially V-shaped cross section.

Here, the upward inclined surface 12b is a surface that inclines in a direction away from the detection surface 12a from the upper surface toward the bottom surface side with respect to the thickness direction Y of the light transmitting member 12, and is arranged so as to face the upward inclined surface 12b. The light emitted from the light irradiation unit B is incident on the main body portion 12c in a state of being inclined with respect to the length direction X orthogonal to the thickness direction Y of the light transmissive member 12.
Further, the distance W between the light incident position on the upward inclined surface 12b and the light irradiation position on the detection surface 12a is preferably 1.0 mm to 50.0 mm as the shortest distance.
Further, the light incident on the main body 12c is guided to the detection surface 12a in a state of being reflected by the bottom surface of the main body 12c as few times as possible, preferably only once, and is guided to the detection surface 12a on the back surface of the detection surface 12a. It is totally reflected and an evanescent field is formed near the surface of the detection surface 12a (first light incident structure).

When the target substance detection device is configured by using the detection chip 10, the light irradiation unit B is arranged at a position on the upper surface side of the light transmissive member 12 facing the upward inclined surface 12b, as shown in FIG.

In the detection chip 10 configured as described above, the distance W between the light incident position on the upward inclined surface 12b and the light irradiation position on the detection surface 12a is the upward inclined surface 2b (light) in the detection chip 1 in the first embodiment. Since it is shorter than the distance between the light incident position on the side surface of the transmissive member 2) and the light irradiation position on the detection surface 2a, it is possible to suppress the attenuation of the light traveling in the main body portion 12c.
Since the other configurations and effects are the same as those of the target substance detection device according to the first embodiment, the description thereof will be omitted.

Subsequently, a supplementary explanation will be given with reference to FIGS. 3 to 5 regarding the incident angle of light with respect to the upwardly inclined surface 2b of the light transmitting member 2 of the detection chip 1 in the first embodiment. It should be noted that each figure of FIGS. 3 to 5 is an explanatory view showing an example of the incident angle of light.
As shown in FIG. 3, the detection chip 1'has a structure in which a part of the upper surface of the light transmissive member 2'is a detection surface 2a.
Here, in the example shown in FIG. 3, light is transmitted from the normal direction, that is, the direction perpendicular to the upward inclined surface 2b'with respect to the upward inclined surface 2b' configured as the side surface of the light transmitting member 2'. The light irradiation direction of the light irradiation unit B is set so that it is incident inside the sex member 2', and the upwardly inclined surface 2b'when viewed as a V-shaped groove angle with the upper surface side of the light transmissive member 2'opened. It is assumed that θ ₁ , which is an angle formed between the light irradiation unit B and the light irradiation direction of the light irradiation unit B, is 90 °.
As described above, when the light is incident from the direction perpendicular to the upward inclined surface 2b'with θ ₁ set to 90 °, the light is not refracted on the upward inclined surface 2b'. Further, the angle θ ₂ formed by the thickness direction Y of the light transmitting member 2'and the incident direction of light with respect to the bottom surface of the light transmitting member 2', and the bottom surface and side surfaces (upward inclined surface 2b') of the light transmitting member 2'. ) Is equal to the angle α (θ ₂ = α). Since these events occur regardless of the material of the light transmissive member 2', the light reflection position in the main body of the light transmissive member 2'is uniquely specified based on the setting of the angle α. It is possible to simplify the setting of the position of the detection surface 2a'on the detection chip and the setting of the optical system on the target substance detection device. In the example shown in FIG. 3, if the angle α is too small, θ ₂ is also too small, and the incident light is not totally reflected by the bottom surface of the light transmitting member 2'and is transmitted to the outside of the light transmitting member 2'as it is. Produces ingredients. In this state, it should be noted that the incident light will not be applied to the detection surface 2a'under the total reflection condition. On the other hand, if the angle α is too large, it becomes difficult for light to enter from the upper surface side, so the angle α is preferably 50 ° to 80 °.

On the other hand, in the example shown in FIG. 4, the angle formed by the upwardly inclined surface 2b'when viewed as a V-shaped groove angle with the upper surface side of the light transmissive member 2'open and the light irradiation direction of the light irradiation unit B. It is assumed that a certain θ ₁ is less than 90 °.
In this way, when light is incident on the upward inclined surface 2b'with θ ₁ set to less than 90 °, the light refracted by the upward inclined surface 2b'is reflected by the bottom surface of the light transmitting member 2'and guided to the upper surface. Be taken.
However, if the light incident angle θ ₁ is too smaller than 90 °, the light refracted by the upward inclined surface 2b'is not totally reflected by the bottom surface of the light transmitting member 2', and is directly outside the light transmitting member 2'. Produces a transparent component. In this state, it should be noted that the incident light will not be applied to the detection surface 2a'under the total reflection condition.
Further, if θ ₁ is too smaller than 90 °, the position of the upper surface to which the reflected light is guided becomes too close to the side surface (upward inclined surface 2b'), and it becomes difficult to set the position of this upper surface as the detection surface 2a'. It is necessary to keep in mind.
Therefore, when θ ₁ is set to less than 90 °, the lower limit thereof depends on the angle α, but is the light irradiation direction of the light irradiation unit B and the length direction of the light transmission member 2'on the detection surface 2a'side. It is preferable that the angle formed with X is 90 ° or more.

On the other hand, in the example shown in FIG. 5, the angle formed by the upwardly inclined surface 2b'when viewed as a V-shaped groove angle with the upper surface side of the light transmitting member 2'open and the light irradiation direction of the light irradiation unit B. It is assumed that a certain θ ₁ is an angle exceeding 90 °.
In this way, when light is incident on the upward inclined surface 2b'with θ ₁ as an angle exceeding 90 °, the light refracted by the upward inclined surface 2b'is reflected by the bottom surface of the light transmitting member 2'and is reflected on the upper surface. Is guided by. At the time of reflection, the light refracted by the upward inclined surface 2b'is easily totally reflected by the bottom surface of the light transmissive member 2', which is preferable.
However, it should be noted that if θ ₁ is larger than 90 °, the position of the upper surface from which the reflected light is guided moves away from the upward inclined surface 2b', resulting in an increase in the size of the detection chip 1'.
When θ ₁ is set to an angle exceeding 90 °, the upper limit thereof is an angle that does not reach parallel to the length direction X of the detection chip 1', although the upper limit depends on the angle α. be.

Here, FIGS. 3 to 5 are given to supplementarily explain the incident angle of light with respect to the upwardly inclined surface 2b of the light transmitting member 2 of the detection chip ₁ in the first embodiment. It can also be applied to the upward inclined surface 12b of the light transmitting member 12 of the detection chip 10 in the second embodiment.
However, when θ ₁ is an angle exceeding 90 °, if θ ₁ is too larger than 90 °, the light transmissivity forming the surface opposite to the upward inclined surface 12b of the V-shaped upper surface side notch portion 15. It should be noted that the constituent parts of the member 12 obstruct the light irradiation, and the angle setting of θ ₁ is restricted. On the contrary, when θ ₁ is 90 ° and less than 90 °, such a restriction is unlikely to occur.

<Third Embodiment>
Next, the target substance detection device according to the third embodiment will be described with reference to FIG. Note that FIG. 6 is an explanatory diagram illustrating an outline of the target substance detection device according to the third embodiment.
As shown in FIG. 6, the detection chip 20 in the third embodiment has a light transmitting member 22. The light transmissive member 22 is a plate-shaped member, and a part of the upper surface thereof is a detection surface 22a, and the body portion receives light from the upper surface and is a main body portion 22c capable of guiding the inside. Further, on the upper surface of the light transmissive member 22, a side wall portion 24 is erected around the detection surface 22a so as to form a box-shaped body having the detection surface 22a as the bottom, and the liquid sample A is introduced into the box-shaped body. Will be done.
Unlike the light transmissive member 2 in the first embodiment, the light transmissive member 22 has a downwardly inclined surface 22b that inclines in a direction away from the detection surface 22a as the side surface moves from the bottom surface to the upper surface side with respect to the thickness direction Y. The light is incident on the upper surface of the light transmissive member 22 at a position facing the side surface in the thickness direction Y.

Here, the light radiated from the light irradiation unit B to the upper surface is reflected in the order of the downward inclined surface 22b and the bottom surface as shown in the figure after being introduced into the main body portion 22c, and is totally reflected at the position of the detection surface 22a. It is reflected and forms an evanescent field near the surface of the detection surface 22a (second light incident structure).

As described above, unlike the detection chip 1 in the first embodiment in which the side surface of the light transmissive member 2 faces the upper surface side, the detection in the third embodiment in which the side surface of the light transmissive member 2 faces the bottom surface side. Also in the chip 20, an evanescent field can be obtained as in the detection chip 1 in the first embodiment.

<Fourth Embodiment>
Next, the target substance detection device according to the fourth embodiment will be described with reference to FIG. 7. Note that FIG. 7 is an explanatory diagram illustrating an outline of the target substance detection device according to the fourth embodiment.

As shown in FIG. 7, the detection chip 30 in the fourth embodiment has a light transmitting member 32. In the light transmissive member 32, unlike the light transmissive member 2 in the first embodiment, a liquid sample storage groove 34 for introducing the liquid sample A is formed on the upper surface thereof. The liquid sample storage groove 34 is formed in a shape having a substantially V-shaped cross section, and a surface forming one side of the groove having a substantially V-shaped cross section is referred to as a detection surface 32a.

Here, unlike the light transmissive member 2 in the first embodiment, the light transmissive member 32 has a downwardly inclined surface 32b that inclines in a direction away from the detection surface 32a as the side surface moves from the bottom surface to the upper surface side with respect to the thickness direction Y. The light is incident on the upper surface of the light transmissive member 32 at a position facing the side surface in the thickness direction Y.
The light irradiation unit B irradiates the upper surface of the light transmissive member 32 with light from the direction Y in the thickness direction, that is, from the direction perpendicular to the upper surface, and the light incident on the main body portion 32c is the downward inclined surface 32b. Is reflected only once, that is, it is propagated in the main body 32c along the length direction X without being reflected on the upper surface and the bottom surface of the main body 32c, and is totally reflected and detected at the position of the detection surface 32a. An evanescent field is formed near the surface of the surface 32a (second light incident structure).

In the detection chip 30 configured in this way, the light incident on the main body 32c is guided to the detection surface 32a without being reflected by the upper surface and the bottom surface of the main body 32c, so that the light is guided to the detection surface 32a on the upper surface and the bottom surface. It is possible to suppress the deterioration of the light due to the reflection of the light.
Further, since the other configurations and effects are the same as those of the target substance detection device according to the first embodiment, the description thereof will be omitted.

[Fifth Embodiment]
Next, the target substance detection device according to the fifth embodiment will be described with reference to FIG. Note that FIG. 8 is an explanatory diagram illustrating an outline of the target substance detection device according to the fifth embodiment.

The detection chip 40 in the fifth embodiment is a modification of the detection chip 10 in the second embodiment, and like the detection chip 10 in the second embodiment, the detection surface 42a, the upward inclined surface 42b, the main body portion 42c, and the liquid sample. A light transmitting member 42 having a storage groove 44 is provided.
In the detection chip 40 in the fifth embodiment, the upper surface side notch portion 45 is different from the detection chip 10 according to the second embodiment, and the upper surface side notch portion 45 has a lower refractive index than the material for forming the main body portion 42c. The refraction material 45a is embedded.

In the detection chip 40 configured in this way, the low refraction material 45a is embedded in the notch portion 45 on the upper surface side, and the entire upper surface of the light transmissive member 42 is in a flat state, so that the liquid sample A is introduced and discharged. The inside of the notch 45 on the upper surface side is not contaminated by the liquid sample A that sometimes invades from the liquid sample storage groove 44.
Further, even when the upper surface side notch portion 45 is configured in this way, the refraction of light on the upwardly inclined surface 42b forming the interface between the low refraction material 45a and the main body portion 42c formed of the high refraction material is utilized. Similar to the detection chip 10 in the second embodiment, the light emitted from the light irradiation unit B can be guided to the detection surface 42a in a state of being reflected only once in the main body portion 42c.
Since the other configurations and effects are the same as those of the target substance detection device according to the second embodiment, the description thereof will be omitted.

Subsequently, the detection chip 40 in the fifth embodiment will be supplementarily described with reference to the modified examples shown in FIGS. 9 and 10. It should be noted that each of FIGS. 9 and 10 is an explanatory diagram showing a modified example.
As shown in FIG. 9, the detection chip 40'has a structure in which a part of the upper surface of the light transmissive member 42'is a detection surface 42'and a notch portion 45'on the upper surface side is arranged.
Here, in the example shown in FIG. 9, as compared with the example shown in FIG. 8, the light irradiation unit B is on the upper surface side of the light transmitting member 42'with respect to the upward inclined surface 42 b'of the upper surface side notch portion 45'. The angle formed by the upwardly inclined surface 42b'and the light irradiation direction of the light irradiation unit B when viewed as a V-shaped groove angle in which the upper surface side of the light transmissive member 42'is opened. The angle β) in FIG. 9 is set at a relatively small angle.
When β is small, the light introduced from the upward inclined surface 42b'is not totally reflected by the bottom surface of the light transmitting member 42', and a component is generated which is transmitted to the outside of the main body portion 42c' in the light transmitting member 42'as it is. Therefore, it should be noted that in this state (see the dotted arrow in FIG. 9), the incident light is not emitted to the back surface under the total reflection condition.
Therefore, β must be at least the minimum angle at which the incident light can satisfy the total reflection condition with respect to the detection surface 42'.
Even when the low refraction material 45a'is not embedded in the notch portion 45'on the upper surface side, if the refractive index of the light transmissive member 42'is not high, the light refracted by the upward inclined surface 42b'is the light transmissive member. It should be noted that a component that is not totally reflected at the bottom surface of the 42'and is transmitted to the outside of the light transmitting member 42' as it is is generated.

Further, even when the light incident angle β is set to a relatively small angle, as shown in FIG. 10, the light transmissive member 42'is formed to be inclined with respect to the in-plane direction of the bottom surface, and is a downwardly inclined surface. By forming the bottom surface side notch 46 having 46a on the bottom surface of the light transmitting member 42', the reflected light is guided to the detection surface 42a'set on the upper surface so as to be a total reflection condition. You may. The bottom surface side notch portion 46 can be formed in the same manner as the top surface side notch portion 45'. Further, the low refraction material 46a may be embedded in the bottom surface side notch portion 46 as in the case of the top surface side notch portion 45'.

[Sixth Embodiment]
Next, the target substance detection device according to the sixth embodiment will be described with reference to FIG. Note that FIG. 11 is an explanatory diagram illustrating an outline of the target substance detection device according to the sixth embodiment.

The detection chip 50 in the sixth embodiment is a modification of the detection chip 20 in the third embodiment.
As shown in FIG. 11, the detection chip 50 in the sixth embodiment has a light transmitting member 52. In the light transmitting member 52, unlike the light transmitting member 22 in the third embodiment, a liquid sample storage groove 54 for introducing the liquid sample A is formed on the upper surface thereof. The liquid sample storage groove 54 is formed in a concave cross section, and the bottom surface thereof is a detection surface 52a.
Further, unlike the light transmitting member 22 in the third embodiment, the light transmitting member 52 is formed on the bottom surface and has a bottom surface side notch 56 having a downward inclined surface 52b, and the bottom surface side notch portion 56 is formed. A low-refractive-index material 56a having a refractive index lower than that of the material for forming the main body 52c is embedded in the body, if necessary.

In the detection chip 50 configured in this way, since the bottom surface side notch 56 is formed on the bottom surface of the light transmissive member 52, the liquid sample that invades from the liquid sample storage groove 54 when the liquid sample A is introduced and discharged. Due to A, the inside of the notch portion 56 on the bottom surface side is not contaminated.
Further, when the bottom surface side notch 56 is configured by embedding the low refraction material 56a, it is possible to prevent the downward inclined surface 52b from being exposed to the outside and being contaminated by adhesion of dust or the like in the atmosphere.
Further, also in the bottom surface side notch 56, the light emitted from the light irradiation unit B is reflected once by the downward inclined surface 52b and the bottom surface by utilizing the reflection of the light on the downward inclined surface 52b, and the detection surface 52a is also used. Can be guided to (second light incident structure).
Since the other configurations and effects are the same as those of the target substance detection device according to the third embodiment, the description thereof will be omitted.

[7th Embodiment]
Next, the target substance detection device according to the seventh embodiment will be described with reference to FIG. Note that FIG. 12 is an explanatory diagram illustrating an outline of the target substance detection device according to the seventh embodiment.

The target substance detection device according to the seventh embodiment relates to a modified example in which the target substance detection device according to the first embodiment is used at an angle of 90 °. Therefore, in the target substance detection device according to the seventh embodiment, the "top surface" and "bottom surface" of the target substance detection device according to the first embodiment are located sideways, and the "side surface" is located above, but the magnetic field application unit C The positional relationship between the "top surface", "bottom surface", and "side surface" in the target substance detection device according to the first embodiment is maintained, assuming that the surface of the light transmissive member 62 on the side to which is arranged is viewed as the "bottom surface". I will give an explanation.
The detection chip 60 in the seventh embodiment is a modification of the detection chip 1 in the first embodiment.
As shown in FIG. 12, the detection chip 60 in the seventh embodiment has a light transmitting member 62. Unlike the light-transmitting member 2 in the first embodiment, the light-transmitting member 62 is formed with a liquid sample storage groove 64 on the side surface for introducing the liquid sample A.
The liquid sample storage groove 64 is formed as a drilling groove having a concave cross section, and among the surfaces constituting the drilling groove, the surface facing the bottom surface at the position closest to the bottom surface is referred to as a detection surface 62a.
As described above, the target substance detection device and the target substance detection method according to the present invention can detect the target substance in any direction as long as the relative positional relationship between the “top surface”, “bottom surface” and “side surface” is maintained. It can be used by changing the posture of the device.
Since the other configurations and effects are the same as those of the target substance detection device according to the first embodiment, the description thereof will be omitted.

1,1', 10,20,30,40,40', 50,60 Detection chip 2,2', 12,22,32,42,42', 52,62 Light transmitting member 2a, 2a', 12a , 22a, 32a, 42a, 42a', 52a, 62a Detection surface 2b, 2b', 12b, 42b, 42b', 62b Upward inclined surface 2c, 12c, 22c, 32c, 42c, 42c', 52c, 62c Main body 4 , 24 Side wall portion 14, 34, 44, 54, 64 Liquid sample storage groove 15, 45, 45'Top side notch 45a, 45a', 56a Low refraction material 46, 56 Bottom side notch 22b, 32b, 46a , 52b Downward inclined surface A Liquid sample B Light irradiation part C Magnetic field application part D Light detection part W Distance X Length direction Y Thickness direction θ ₁ , θ ₂ , α, β Angle

Claims (9)

A detection surface arranged on the surface on the upper surface side with respect to the bottom surface, an upwardly inclined surface that inclines in a direction away from the detection surface as it goes from the upper surface to the bottom surface side in the thickness direction, and from the bottom surface in the thickness direction. Overall substantially plate-like light having one of the inclined surfaces of the downward inclined surface that inclines toward the upper surface side and away from the detection surface, and a main body portion that receives light and can guide the inside. A first light having a transmissive member and having the light transmissive member irradiated from the upper surface side and passing through the upwardly inclined surface is incident on the detection surface through the main body under all reflection conditions. Any of the incident structure and the light incident structure of the second light incident structure in which the light emitted from the upper surface side and reflected by the downward inclined surface is incident on the detection surface via the main body under all reflection conditions. With a detection chip that has
A light irradiation unit arranged on the upper surface side of the light transmissive member and capable of irradiating the detection surface with the light under total reflection conditions via the light incident structure.
A magnetic field application portion arranged on the bottom surface side of the light transmissive member,
Light detection that is arranged on the detection surface and has a region near the surface of the detection surface as a detection region, and is capable of detecting an optical signal emitted from a conjugate containing a target substance and magnetic particles upon irradiation with the light. Department and
Equipped with
A cross section in which the light transmissive member is formed on the upper surface and has a V-shaped upper surface side notch having an upward inclined surface and a bottom surface having the downward inclined surface. A target substance detection device having at least one notch of a V-shaped bottom surface side notch. The target substance detection device according to claim 1, wherein a low-refractive index material having a refractive index lower than that of the main body is embedded in the notch. The light incident structure reflects at least one of the light passed through the upwardly inclined surface in the first light incident structure and the light reflected by the downwardly inclined surface in the second light incident structure on the detection surface after being reflected by the bottom surface. The target substance detection device according to any one of claims 1 to 2, which is capable of incident light under total reflection conditions. The target substance detection device according to any one of claims 1 to 3, wherein the shortest distance between the light incident position on the inclined surface and the light irradiation position on the detection surface is 1.0 mm to 50.0 mm. The target substance detection device according to any one of claims 1 to 4, wherein the thickness of the light transmissive member is 0.1 mm to 10.0 mm. The target substance detection device according to any one of claims 1 to 5, wherein a liquid sample storage groove having at least a part as a detection surface is formed on the upper surface of the light transmissive member. The target substance detection device according to claim 6, wherein the liquid sample storage groove has an inclined detection surface as a detection surface, which is inclined in a direction away from the inclined surface from the upper surface toward the bottom surface side with respect to the thickness direction of the light transmissive member. Claims 1 to 5 in which a part of the upper surface of the light transmissive member is used as a detection surface and a side wall portion is erected around the detection surface so as to form a box-shaped body having the detection surface as the bottom. The target substance detection device according to any one. A method for detecting a target substance using the target substance detecting device according to any one of claims 1 to 8.
A light irradiation step of irradiating the detection surface with light from the upper surface side of the light transmissive member via a light incident structure under total reflection conditions, and
A magnetic field application step of applying a magnetic field from the bottom surface side of the light transmissive member, and
A light detection step of detecting an optical signal emitted from a conjugate containing a target substance and magnetic particles upon irradiation with light, and a light detection step.
A method for detecting a target substance, which comprises.

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