JP5746643B2 - Measuring system and measuring method - Google Patents

Description

Embodiments described below generally, measurement system, and a measurement method.

A fine particle having an antibody that specifically binds to a measurement target substance and an optical waveguide to which an antibody that specifically binds to the measurement target substance is fixed, and the fine particle is separated from the optical waveguide through the measurement target substance by an antigen-antibody reaction. There is an optical waveguide sensor chip that is coupled to the surface.
In such a measurement method using an optical waveguide sensor chip, the amount of the substance to be measured is measured based on the absorbance caused by the fine particles bound to the surface of the optical waveguide by the antigen-antibody reaction. Therefore, the amount of the substance to be measured can be measured without performing a procedure for removing surplus specimens and secondary antibodies.
However, the fine particles may be adsorbed nonspecifically, that is, adsorbed on the surface of the optical waveguide irrespective of the antigen-antibody reaction. In such a case, light is absorbed and scattered also by the fine particles adsorbed on the surface of the optical waveguide regardless of the antigen-antibody reaction, which may cause a measurement error. Further, since the microparticles and the sample solution are mixed at the time of measurement, a complicated manual operation or an automatic machine for mixing is required, and the advantages of the method using the optical waveguide sensor chip may be impaired. .
Therefore, it has been desired to develop a technique capable of performing measurement with higher accuracy by reducing noise components due to nonspecific adsorption. In addition, there has been a demand for a technique for returning to a dispersible state capable of reacting without adding manual or mechanical stirring.

JP 2009-020097 A

An object of the present invention is to provide is to provide a constant system measurement can be measured with high accuracy, and a measurement method.

The measurement system according to the embodiment includes a sensor chip, a magnetic field applying unit that applies a magnetic field to the sensor chip, a light source that emits light toward the sensor chip, and a light receiving unit that receives light emitted from the sensor chip. And an element.
The sensor chip includes an optical waveguide having a sensing area to which a first substance that specifically binds to a measurement target substance is fixed, a reaction part in which a recess for introducing a sample solution is provided facing the sensing area, A second substance that specifically binds to the measurement target substance is fixed, has magnetic properties, and magnetic fine particles having a specific gravity higher than that of the sample solution.
The magnetic field application unit applies the magnetic field having a magnetic field strength such that the magnetic fine particles are separated from the sensing area by a distance satisfying the following expression.
L> λ / {2π (n ₁ sin ² θ-n ₂ ² ) ^1/2 }
Here, L is the distance that the magnetic fine particles are separated from the sensing area, λ is the wavelength of light used for measurement, n ₁ is the refractive index of the optical waveguide, n ₂ is the refractive index of the dispersion medium that disperses the magnetic fine particles, θ is the total reflection angle.

It is a schematic diagram for illustrating the sensor chip and the measurement system according to the first embodiment. It is a schematic diagram for illustrating a magnetic fine particle. (A)-(c) is a schematic process diagram for illustrating the measuring method which concerns on 1st Embodiment. (A), (b) is a graph for demonstrating the effect which applies an upper magnetic field. It is a schematic diagram for illustrating the measurement system which concerns on 2nd Embodiment. (A)-(d) is a schematic process diagram for illustrating the measuring method which concerns on 2nd Embodiment. (A)-(c) is a graph for demonstrating the effect | action and effect of a magnetic field application part. It is a schematic diagram for illustrating the measurement system which concerns on 3rd Embodiment. (A)-(c) is a schematic process diagram for illustrating the measuring method which concerns on 3rd Embodiment. (A)-(c) is a schematic diagram for demonstrating the structure of a magnetic field application part. (A)-(c) is a schematic diagram for demonstrating the structure of a magnetic field application part.

Hereinafter, embodiments will be illustrated with reference to the drawings. In addition, in each drawing, the same code | symbol is attached | subjected to the same component and detailed description is abbreviate | omitted suitably.
In this specification, “upper”, “upward”, and “upward” are “upper”, “upward”, and “upward” in the direction of gravity, and “lower”, “lower”, and “downward”. And “lower”, “lower” and “down” in the direction of gravity.

[First embodiment]
FIG. 1 is a schematic diagram for illustrating the sensor chip and the measurement system according to the first embodiment. In FIG. 1, a cross section of the sensor chip 100 is shown.
As shown in FIG. 1, the measurement system 30 includes a sensor chip 100 provided with a reaction unit 5, a light source 7, a light receiving element 8, a magnetic field application unit 10, and a control unit 20.
The sensor chip 100 is provided with a substrate 1, grating portions 2 a and 2 b, an optical waveguide portion 3, a protection portion 4, a reaction portion 5, and magnetic fine particles 9.
The sensor chip 100 is an optical waveguide type sensor chip.

The substrate 1 has a flat plate shape and is made of a material that can transmit light emitted from the light source 7. The substrate 1 can be formed from, for example, alkali-free glass or quartz.
A pair of grating portions 2a and 2b is provided in the vicinity of both ends of the main surface of the substrate 1 on the side where the optical waveguide portion 3 is provided. That is, the pair of grating portions 2 a and 2 b are provided at a distance from each other on the main surface of the substrate 1. The grating portion 2a is provided near the end of the substrate 1 on the light incident side, and the grating portion 2a is provided near the end of the substrate 1 on the light emitting side. The grating portions 2 a and 2 b function as a diffraction grating when light is introduced into and emitted from the optical waveguide portion 3. Therefore, the grating portions 2a and 2b have a refractive index higher than that of the substrate 1 and are provided in a lattice shape with a predetermined pitch dimension. The grating portions 2a and 2b are formed of, for example, titanium oxide (TiO ₂ ), tin oxide (SnO ₂ ), zinc oxide, lithium niobate, gallium arsenide (GaAs), indium tin oxide (ITO), polyimide, or the like. Can be.

The optical waveguide portion 3 is provided on the main surface of the substrate 1 on the side where the grating portions 2a and 2b are provided. The optical waveguide portion 3 can be a so-called planar optical waveguide. The optical waveguide portion 3 is formed of a material that can transmit light emitted from the light source 7. In this case, the optical waveguide part 3 can have a higher refractive index than the substrate 1. For example, the optical waveguide portion 3 can be formed from a thermosetting resin such as a phenol resin, an epoxy resin, or an acrylic resin, a photocurable resin, or an alkali-free glass. The thickness dimension of the optical waveguide part 3 can be 3 micrometers or more and 300 micrometers or less, for example.
The grating portions 2a and 2b may be provided by forming a concavo-convex pattern on the upper surface of the optical waveguide portion 3 using a photolithography process or the like.

  The protection part 4 is provided so as to cover both ends of the optical waveguide part 3 and a part facing the region where the grating parts 2a and 2b are formed. The protective part 4 is provided with an opening 4a through which the surface of the optical waveguide part 3 is exposed. The opening 4 a can be, for example, a rectangular shape, and the surface of the optical waveguide portion 3 exposed to the opening 4 a becomes a sensing area (detection surface) 101. The protection part 4 can be formed from a material having a lower refractive index than the material forming the optical waveguide part 3, for example. The protection part 4 can be formed from, for example, a fluororesin.

A first substance 6 that specifically reacts with the measurement target substance 14 in the sample solution is fixed to the sensing area 101 that is the detection surface. The first substance 6 can be fixed by, for example, hydrophobic interaction or chemical bond between the first substance 6 and the sensing area 101. For example, the first substance 6 can be fixed to the sensing area 101 by performing a hydrophobic treatment with a silane coupling agent. Alternatively, a functional group may be formed in the sensing area 101 and a known linker molecule may be allowed to act to fix the first substance 6 to the sensing area 101 by chemical bonding.
For example, when the measurement target substance 14 in the sample solution is an antigen, the first substance 6 can be an antibody (primary antibody).

The reaction unit 5 is provided with a recess 5a for introducing the sample solution and a hole 5b penetrating the recess 5a. The reaction unit 5 is provided so that the recess 5a faces the sensing area 101. A space defined by the recess 5 a and the sensing area 101 is a reaction space 102. The reaction unit 5 holds the introduced sample solution and the magnetic fine particles 9 in the reaction space 102.
The hole 5b serves as a hole for introducing the sample solution into the reaction space 102 and a hole for venting air. The number of holes 5b and the positions to be provided are not limited to those illustrated in FIG. 1 and can be changed as appropriate.
The reaction unit 5 can be formed of a resin having resistance to the sample solution.

The magnetic fine particles 9 are held in the reaction space 102. In this case, for example, the magnetic fine particles 9 can be held by applying to a surface holding a slurry containing the magnetic fine particles 9 and a water-soluble substance and drying the slurry. The magnetic fine particles 9 can be held on a surface other than the sensing area 101 in the reaction space 102. For example, as shown in FIG. 1, the magnetic fine particles 9 can be held on a surface facing the sensing area 101 of the recess 5a. The magnetic fine particles 9 may be held on a surface other than the surface facing the sensing area 101 of the recess 5a. However, if the magnetic fine particles 9 are held on the surface of the recess 5a facing the sensing area 101, the dispersibility in the sample solution can be improved.
Further, the magnetic fine particles 9 can be held by a holding plate (not shown) disposed with a space above the sensing area 101.

The magnetic fine particles 9 may be held directly on the held surface, or may be held indirectly on the held surface via a blocking layer (not shown).
The blocking layer may contain a water-soluble substance such as polyvinyl alcohol, bovine serum albumin (BSA), polyethylene glycol, phospholipid polymer, gelatin, casein, and sugars (eg, sucrose and trehalose).

Further, the magnetic fine particles 9 are held in a dry or semi-dry state on the surface of the recess 5a. In this case, it is desirable that the magnetic fine particles 9 be held in a state where they can be easily dispersed when in contact with a dispersion medium such as a sample solution. However, the magnetic fine particles 9 do not necessarily need to be uniformly dispersed and held, and may have a certain degree of bias.
The magnetic fine particles 9 held in a dry or semi-dry state on the surface of the recess 5a are dispersed in the sample solution when the sample solution is introduced.

FIG. 2 is a schematic diagram for illustrating the magnetic fine particles 9.
The magnetic fine particle 9 has a fine particle 12 and a second substance 13 fixed on the surface of the fine particle 12.
The fine particles 12 are, for example, in a form in which the surface of particles formed from a magnetic material is coated with a polymer material, or in a form in which the surface of particles formed from a polymer material is coated with a magnetic material. be able to. Alternatively, it may be a particle itself made of a magnetic material, and in this case, it may have means for binding the second substance to the surface of the particle by a hydrophobic bond or a covalent bond.
Examples of the magnetic material used for the fine particles 12 include various ferrites such as γ-Fe2O3. In this case, it is preferable to use a superparamagnetic material that quickly loses magnetism when the application of the magnetic field is stopped.
If a superparamagnetic material is used, even if the magnetic fine particles 9 aggregate due to magnetization when a magnetic field is applied, they can be easily redispersed by stopping the application of the magnetic field.
For example, even if a magnetic field is applied when the measurement target substance 14 is not present in the sample solution, an aggregate of the magnetic fine particles 9 may be generated and hardly peeled off from the sensing area 101 in some cases. Such agglomerates of magnetic fine particles 9 cause measurement errors. In this case, if the fine particles 12 are formed of a superparamagnetic material, aggregation of the magnetic fine particles 9 can be suppressed, and therefore, generation of measurement errors can be suppressed.

Further, in order to further improve the redispersibility when the application of the magnetic field is stopped, the surface of the fine particles 12 may have a positive or negative charge. Alternatively, a dispersant such as a surfactant may be added to the dispersion medium (for example, the sample solution) of the magnetic fine particles 9.
If the surface of the fine particles 12 is positively or negatively charged, or a dispersant such as a surfactant is added, the magnetic fine particles 9 can be easily redispersed when the application of the magnetic field is stopped, and stirring is further performed. Can be promoted. Thereby, it is possible to perform measurement with higher accuracy.

  The particle size of the fine particles 12 is preferably 0.05 μm or more and 200 μm or less, more preferably 0.2 μm or more and 20 μm or less. If the fine particles 12 having such a particle size are used, the light scattering efficiency can be increased. Therefore, it is possible to perform highly accurate measurement in the measurement system 30 that measures the amount and concentration of the measurement target substance 14 using light.

For example, when the measurement target substance 14 in the sample solution is an antigen, the second substance 13 can be an antibody (secondary antibody).
The second substance 13 can be fixed to the surface of the fine particle 12 by, for example, physical adsorption or chemical bonding via a carboxyl group or an amino group.
The combination of the measurement target substance 14 and the first substance or the second substance is not limited to the combination of the antigen and the antibody.
For example, when the measurement target substance 14 is a sugar, the first substance and the second substance are lectins, and when the measurement target substance 14 is a nucleotide chain, the first substance and the second substance are complementary to each other. In the case of a nucleotide chain and when the substance 14 to be measured is a ligand, the first substance and the second substance can be receptors for the first substance and the second substance.

The light source 7 emits light toward the sensor chip 100. The light source 7 can be, for example, a red laser diode.
The light receiving element 8 receives light from the sensor chip 100 and measures the light intensity. The light receiving element 8 can be, for example, a photodiode.
Light emitted from the light source 7 and incident on the grating part 2 a on the incident side through the substrate 1 is diffracted by the grating part 2 a and propagates while reflecting inside the optical waveguide part 3. Near-field light such as evanescent light is generated in the sensing area 101 by light propagating while reflecting the inside of the optical waveguide section 3. Near-field light is light generated at the interface when the light is totally reflected at the interface between the optical waveguide section 3 and the reaction space 102. The distance that the near-field light reaches (seeding distance) is about a fraction of the wavelength from the surface of the optical waveguide section 3 (the surface of the sensing area 101).
Near-field light is absorbed or scattered by the magnetic fine particles 9 in the vicinity of the sensing area 101. At this time, near-field light is absorbed and scattered according to the amount of the magnetic fine particles 9.

Thereafter, the light is diffracted by the grating part 2b on the emission side and emitted toward the outside. The light emitted toward the outside is received by the light receiving element 8 and the light intensity is measured.
Since the reduction rate of the light intensity can be obtained based on the light intensity emitted toward the outside and the reference light intensity, the amount of the magnetic fine particles 9 in the sensing area 101 can be known. Then, the amount and concentration (for example, antigen concentration) of the measurement target substance 14 in the sample solution can be obtained based on the obtained amount of the magnetic fine particles 9.
Details regarding the determination of the amount and concentration of the measurement target substance 14 in the sample solution based on the amount of the magnetic fine particles 9 will be described later.

The magnetic field application unit 10 generates a magnetic field and applies the generated magnetic field to the sensor chip 100 to change the position of the magnetic fine particles 9 according to the magnetic field. The magnetic field application unit 10 can be provided on the side opposite to the side where the optical waveguide unit 3 is present when viewed from the magnetic fine particles 9.
For example, in the case of the measurement system 30, the magnetic field application unit 10 is provided above the sensor chip 100.
The magnetic field application unit 10 may have, for example, a permanent magnet or an electromagnet.
When the magnetic field application unit 10 includes a permanent magnet such as a ferrite magnet, the magnetic field strength can be adjusted by changing the magnetic force of the permanent magnet or the distance from the sensor chip 100.

In this case, the distance between the permanent magnet and the sensor chip 100 is such that the thickness dimension of the spacer provided between the permanent magnet and the sensor chip 100 is changed or an actuator such as a linear motor is used. It can be changed by changing the relative position with respect to 100.
In the case where the magnetic field application unit 10 includes an electromagnet, the magnetic field strength can be adjusted by changing the value of the current flowing through the coil.
In this case, in order to dynamically adjust the magnetic field strength, it is preferable to adjust the magnetic field strength according to the current value using an electromagnet.

The control unit 20 controls the magnetic field application unit 10 to control the magnetic field strength of the magnetic field applied by the magnetic field application unit 10.
For example, the control unit 20 senses the magnetic fine particles 9 in the state (state 2) and (state 3) described later without peeling off the magnetic fine particles 9 in the state (state 1) described later from the sensing area 101. The magnetic field application unit 10 is controlled so that the magnetic field intensity can be removed from the area 101 to a distance that does not affect the measurement.
The control unit 20 can also adjust the magnetic field strength dynamically by controlling the magnetic field application unit 10.
For example, the control unit 20 can control the magnetic field application unit 10 to control at least one of the timing of applying the magnetic field and the length of time.
In this case, the control unit 20 can control the magnetic field application unit 10 to apply the magnetic field in a pulsed manner.

Next, the measurement method according to the first embodiment will be exemplified together with the operation of the measurement system 30.
FIG. 3 is a schematic process diagram for illustrating the measurement method according to the first embodiment.
3A to 3C illustrate a method of measuring the concentration of the measurement target substance 14 using the measurement system 30. FIG.
3A to 3C, the state in the reaction space 102 is represented in order to avoid complications.

  First, as shown in FIG. 3A, the sample solution is introduced into the reaction space 102 in which the magnetic fine particles 9 are held, and the magnetic fine particles 9 are dispersed in the sample solution.

That is, the sample solution containing the measurement target substance 14 and the magnetic fine particles 9 in which the second substance 13 that specifically binds to the measurement target substance 14 is fixed and have a magnetic property and higher specific gravity than the sample solution are the measurement target substance 14. The first substance 6 that specifically binds to the sensing area 101 is fixed.
The sample solution can be introduced, for example, through the hole 5b.

  Next, as shown in FIG. 3B, the magnetic fine particles 9 settle (sedimentation) toward the sensing area 101 due to gravity. At this time, a first substance 6 (for example, a primary antibody) immobilized on the sensing area 101 and a second substance 13 (for example, a secondary antibody) immobilized on the surface of the microparticles 12 are measured substances 14 (for example, It binds by antigen-antibody reaction via the antigen). Thereby, a part of the magnetic fine particles 9 is coupled to the sensing area 101.

Next, as shown in FIG. 3C, by applying a magnetic field from a direction (for example, upward direction) different from the sedimentation direction when viewed from the magnetic fine particles 9, the sensing area 101 is not passed through the measurement target substance 14. The magnetic fine particles 9 adsorbed on the magnetic particles 9 are removed from the sensing area 101 by moving in a direction (for example, upward) different from the settling direction.
At this time, by setting the magnetic field strength to an appropriate value, the magnetic fine particles 9 bound to the sensing area 101 through the measurement target substance 14 by the antigen-antibody reaction are not peeled off, and the sensing area is not passed through the measurement target substance 14. Only the magnetic fine particles 9 adsorbed on 101 are removed.
Details regarding setting the magnetic field strength to an appropriate value will be described later.

Next, the amount and concentration (for example, antigen concentration) of the measurement target substance 14 in the sample solution are measured by measuring the difference in the detection signal intensity ratio from the light receiving element 8.
For example, as described above, near-field light such as evanescent light is generated in the sensing area 101 by making light incident from the light source 7. The sample solution is introduced into the reaction space 102 in a state where the near-field light is generated. The magnetic fine particles 9 held in the reaction space 102 start to settle immediately after the introduction of the sample solution and reach the vicinity of the sensing area 101, for example, the evanescent light region (FIGS. 3A and 3B). The evanescent light region is a region defined by a distance (exudation distance d) that evanescent light described later reaches. The magnetic fine particles 9 in the evanescent light region absorb and scatter evanescent light, so that the light intensity of light propagating through the optical waveguide section 3 is attenuated. The intensity of light emitted from the grating section 2b on the emission side increases as the amount of magnetic fine particles 9 in the evanescent light region increases. Therefore, the intensity of light emitted from the grating portion 2b decreases with the passage of time as the magnetic fine particles 9 settle.

Thereafter, when an upper magnetic field is applied by the magnetic field application unit 10, the magnetic fine particles 9 in (State 2) and (State 3) move out of the evanescent light region (FIG. 3 (c)). Therefore, the light intensity of the light emitted from the grating portion 2b is recovered to a predetermined value. The rate of decrease in light intensity can be determined from the light intensity when recovered to a predetermined value and the state of FIG. 3A, that is, the light intensity immediately after the sample solution is introduced.
In this case, the intensity of light emitted from the sensor chip 100 is measured after the sample solution is introduced into the sensor chip 100 and before the application of the magnetic field. Further, the intensity of light emitted from the sensor chip 100 is measured after application of the magnetic field. And the quantity and density | concentration of the measuring object substance 14 can be quantified based on the difference of these light intensity.

As described above, the light intensity reduction rate of the light incident on the light receiving element 8 depends on the amount of the magnetic fine particles 9 bound to the sensing area 101 by an antigen-antibody reaction or the like. That is, it is proportional to the amount and concentration (for example, antigen concentration) of the measurement target substance 14 in the sample solution involved in the antigen-antibody reaction.
Therefore, the amount and concentration of the measurement target substance 14 in the sample solution can be quantified by the following procedure.
First, a fluctuation curve of light intensity over time in a sample solution with a known amount and concentration of the measurement target substance 14 is obtained.
Next, in this variation curve, by obtaining the light intensity decrease rate (signal decrease rate) when the light intensity variation is saturated after application of the upper magnetic field, the known amount and concentration of the measurement target substance 14 (for example, A calibration curve showing the relationship between (antigen concentration) and the rate of decrease in light intensity is prepared in advance.
Next, a fluctuation curve of light intensity in a sample solution whose amount and concentration of the measurement target substance 14 are unknown is obtained. Then, using this fluctuation curve, the light intensity reduction rate at a predetermined time is obtained.
Next, the amount and concentration of the measurement target substance 14 in the sample solution are quantified from the calibration curve and the obtained light intensity decrease rate.
In this manner, the amount and concentration of the measurement target substance 14 in the sample solution can be measured.

Here, the magnetic field strength will be further illustrated.
The states of the magnetic fine particles 9 that can be measured in the measurement using near-field light such as evanescent light are classified into the following (State 1) to (State 3) depending on the strength of interaction with the sensing area 101. be able to.
(State 1) is a state of the magnetic fine particles 9 bound to the sensing area 101 by binding (for example, antigen-antibody binding) of the measurement target substance 14 and a molecule that specifically binds to the substance 14 to be measured. The magnetic fine particles 9 in (State 1) will be appropriately referred to as magnetic fine particles 9 combined with the sensing area 101.
(State 2) is a state of the magnetic fine particles 9 adsorbed to the sensing area 101 non-specifically by an intermolecular force or hydrophobic interaction. The magnetic fine particles 9 in (State 2) will be referred to as magnetic fine particles 9 adsorbed on the sensing area 101 as appropriate.
(State 3) is a state of the magnetic fine particles 9 floating in the vicinity of the sensing area 101.

In this case, the interaction in (State 1) is the strongest and the interaction in (State 3) is the weakest.
Further, the magnetic fine particles 9 in (State 1) become magnetic fine particles 9 useful for measuring the amount and concentration of the measurement target substance 14.
The magnetic fine particles 9 in (State 2) or (State 3) become magnetic fine particles 9 that can be a measurement error factor (noise) when measuring the amount and concentration of the substance 14 to be measured.

  Here, when the near-field light generated in the sensing area 101 is evanescent light, the distance that the evanescent light reaches (seeding distance d) can be obtained by the following equation (1).

d = λ / {2π (n ₁ sin ² θ-n ₂ ² ) ^1/2 } (1)
Here, d is the evanescent light penetration distance, λ is the wavelength of the light used for measurement, n ₁ is the refractive index of the optical waveguide section 3, and n ₂ is a dispersion medium (for example, a sample solution) in which the magnetic fine particles 9 are dispersed. The refractive index, θ, is the total reflection angle.
From the equation (1), it can be seen that the permeation distance d is approximately a fraction of the wavelength of light used for measurement.

Therefore, the magnetic field application unit 10 may apply a magnetic field having a magnetic field intensity such that the magnetic fine particles 9 are separated from the sensing area 101 by a distance L that satisfies the following expression (2).
L> λ / {2π (n ₁ sin ² θ-n ₂ ² ) ^1/2 } (2)
Here, L is the distance that the magnetic fine particles 9 are separated from the sensing area 101, λ is the wavelength of light used for measurement, n ₁ is the refractive index of the optical waveguide section 3, and n ₂ is a dispersion medium (for example, a dispersion medium for dispersing the magnetic fine particles 9) The refractive index of the sample solution), θ is the total reflection angle.

For example, if λ = 635 nm, n ₁ = 1.58, n ₂ = 1.33 (when the dispersion medium is water), and θ = 78 °, L> 130 nm. Accordingly, the measurement error can be sufficiently reduced by applying the magnetic field and moving the magnetic fine particles 9 in (State 2) and (State 3) slightly from the sensing area 101 by about several hundred nm. In this case, since the distance L that satisfies Equation (2) is very short, the time required to move the magnetic fine particles 9 in (State 2) and (State 3) away from the sensing area 101 is very short. . If the time is within an allowable range, the magnetic fine particles 9 in (state 2) and (state 3) with a weaker magnetic field strength are required to satisfy the formula (2) even if some time is required. It is possible to move to L. Thereby, it can suppress that the magnetic fine particle 9 which is (state 1) is peeled off excessively. Therefore, the magnetic fine particles 9 that are useful for measurement (state 1) are not peeled off from the sensing area 101, and the magnetic fine particles 9 that are in the state (state 2) or (state 3) can be sensed. Since it can be peeled off from the area 101, the S / N ratio can be improved.

That is, an appropriate magnetic field strength can sense the magnetic fine particles 9 in (state 2) and (state 3), which can cause measurement noise without peeling off the magnetic fine particles 9 in (state 1) useful for measurement from the sensing area 101. The magnetic field intensity can be removed from the area 101 to a distance that does not affect the measurement.
In this case, an appropriate magnetic field strength can be obtained by changing the value of the current flowing through the coil of the electromagnet provided in the magnetic field application unit 10. Alternatively, an appropriate magnetic field strength can be obtained by changing the magnetic force of the permanent magnet provided in the magnetic field application unit 10 or the distance from the sensor chip 100.

Next, the effect of applying the upper magnetic field by the magnetic field application unit 10 will be further illustrated.
Here, an experiment performed using the measurement system 30 in order to confirm the effect of applying the upper magnetic field will be described.
In addition, the specific numerical values and materials illustrated below are examples, and are not limited to these numerical values and materials.

The sensor chip 100 used for the experiment was prepared as follows.
First, the grating portions 2a and 2b are formed on the main surface of the light-transmitting substrate 1 made of non-alkali glass or the like. For example, a titanium oxide film having a refractive index of 2.2 to 2.4 is formed to a thickness of 50 nm on the main surface of the substrate 1 using a sputtering method, and the grating portion 2a is formed using a lithography method and a dry etching method. 2b can be formed.
Next, the optical waveguide 3 is formed on the main surface of the substrate 1 so as to cover the grating portions 2a and 2b. For example, the optical waveguide 3 can be formed by applying an ultraviolet curable acrylic resin to a thickness of about 10 μm on the main surface of the substrate 1 using a spin coating method and curing the resin by ultraviolet irradiation. The refractive index of the cured ultraviolet curable acrylic resin (the refractive index of the optical waveguide 3) was 1.58.

  Next, the protection part 4 is formed on the main surface of the optical waveguide 3. The protection part 4 includes a part facing the area where the grating parts 2a and 2b are formed, and is formed so as to surround the antibody immobilization area which is the sensing area 101. The protection part 4 can be formed by applying a low refractive index resin using a screen printing method and drying it. In addition, the refractive index (refractive index of the protection part 4) of the low refractive index resin after drying was 1.34.

Next, the first substance 6 is fixed to the sensing area 101 by a covalent bond method. In this case, since the measurement target substance 14 is an antigen protein of inactivated influenza virus (type A), the first substance 6 is an anti-influenza nucleoprotein antibody.
On the other hand, the magnetic fine particles 9 on which the second substance 13 is fixed in advance are held on the surface of the recess 5 a of the reaction unit 5. For example, the magnetic fine particles 9 can be held by applying to a surface that holds a slurry containing the magnetic fine particles 9 and a water-soluble substance and drying the slurry. The average particle diameter of the fine particles 12 was 1.1 μm.

Next, the reaction part 5 is provided. The reaction unit 5 is provided so that the recess 5a faces the sensing area 101. The reaction unit 5 can be fixed using a double-sided tape or the like.
The center wavelength of the light emitted from the light source 7 was 635 nm.
In this experiment, the magnetic field application unit 10 is a ferrite magnet, a spacer is provided between the ferrite magnet and the sensor chip 100, and the magnetic field strength is changed by changing the thickness of the spacer.

FIG. 4 is a graph for illustrating the effect of applying the upper magnetic field.
FIG. 4A shows a step of removing magnetic fine particles 9 that may become noise by the magnetic field applying unit 10, and FIG. 4B shows a step of stirring the magnetic fine particles 9 and the sample solution by the magnetic field applying unit 10. This is the case.
As shown in FIG. 4A, when the sample solution is introduced into the reaction space 102, the detection signal intensity ratio decreases as the fine particle density increases in the vicinity of the sensing area 101 due to the sedimentation of the magnetic fine particles 9. After that, when the upper magnetic field is applied by the magnetic field application unit 10, the magnetic fine particles 9 that can become noise adsorbed to the sensing area 101 are removed, so that the detection signal intensity ratio rises again and is lower than the initial detection signal intensity ratio. Saturates. The difference between the detection signal intensity ratio and the initial detection signal intensity ratio at this stage is the ratio to the initial detection signal intensity ratio, that is, the signal decrease rate.

  As can be seen from FIG. 4A, when the sensor chip 100, the measurement system 30, and the measurement method according to the present embodiment are used, the magnetic fine particles 9 in (state 2) and (state 3) that can become measurement noise can be obtained. It can be peeled off from the sensing area 101 to a distance that does not affect the measurement. Therefore, even when the concentration of the measurement target substance 14 is low, highly accurate measurement can be performed.

  4B, after introducing the sample solution into the reaction space 102, the magnetic field application unit 10 applies an upper magnetic field in a pulsed manner. For example, the upper magnetic field is applied every 10 seconds by the magnetic field application unit 10. Thereafter, when the magnetic fine particles 9 are allowed to settle, the detection signal intensity ratio decreases as the fine particle density in the vicinity of the sensing area 101 increases. Next, when the upper magnetic field is applied by the magnetic field application unit 10, the magnetic fine particles 9 that can become noise adsorbed to the sensing area 101 are removed, so that the detection signal intensity ratio rises again and is lower than the initial detection signal intensity ratio. Saturates at.

  Here, in the case shown in FIG. 4B, the detection signal intensity ratio after removing the magnetic fine particles 9 that may be noise is lower than in the case of FIG. 4A. That is, in the case of FIG. 4B, the amount of magnetic fine particles 9 coupled to the sensing area 101 via the measurement target substance 14 is increased. When attention is paid to the speed of signal decrease due to natural sedimentation after the upper magnetic field is applied in a pulse shape, in the case shown in FIG. 4B, the signal due to natural sedimentation after introduction of the sample solution in FIG. Compared with the decrease rate, the signal decrease rate is moderate. This suggests that the degree of aggregation of the fine particles released into the specimen solution from the dry or semi-dry state is smaller in FIG. 4B than in FIG. 4A.

When the upper magnetic field is applied in a pulse form by the magnetic field application unit 10, the magnetic fine particles 9 and the sample solution can be stirred. Therefore, the reaction rate between the second substance 13 fixed to the fine particles 12 of the magnetic fine particles 9 and the measurement target substance 14 is increased, and the amount of the magnetic fine particles 9 coupled to the sensing area 101 via the measurement target substance 14 is increased. For this reason, it is considered that the amount of the magnetic fine particles 9 coupled to the sensing area 101 via the measurement target substance 14 has increased. In addition, it is considered that dispersion by natural diffusion was promoted because the time of floating in the specimen solution was increased by applying the upper magnetic field in pulses.
If the reaction rate between the second substance 13 fixed to the fine particles 12 of the magnetic fine particles 9 and the measurement target substance 14 can be increased, the measurement of the measurement target substance 14 can be performed with higher accuracy.
In addition, although the case where the upper magnetic field was applied was illustrated as an example, it is not necessarily limited to this. The present invention can be applied to magnetic field application for moving the magnetic fine particles 9 away from the sensing area 101. For example, in the case shown in FIG. 8 to be described later, the lower magnetic field may be applied in the form of pulses. Further, the upper magnetic field and the lower magnetic field may be applied in a pulse shape by shifting the application timing. By doing so, the magnetic fine particles 9 and the sample solution can be further agitated.

According to the present embodiment, by providing magnetic particles having a specific gravity higher than that of the sample solution in the reaction space 102 in a dry or semi-dried state in advance, when the sample solution is introduced, the fine particles start to settle by their own weight, and thus manually. It is possible to return to a dispersible state capable of reacting without adding stirring by mechanical means. In addition, by applying a magnetic field in a pulsed manner, sedimentation in the direction of gravity and movement in a direction other than the direction of gravity are repeated, resulting in a longer time for the fine particles to float in the solution. It can be further promoted.
Further, by applying a magnetic field to the magnetic fine particles 9 in a direction different from the settling direction, the magnetic fine particles 9 that may be noise adsorbed on the sensing area 101 without being caused by an antigen-antibody reaction or the like are peeled off from the sensing area 101. be able to. Thereby, it is possible to perform measurement with the magnetic fine particles 9 bound to the sensing area 101 via the measurement target substance 14 by an antigen-antibody reaction or the like. Therefore, it is possible to perform measurement with higher accuracy.
In addition, since the magnetic fine particles 9 that can become noise can be removed by applying a magnetic field, the work of removing such magnetic fine particles 9 by washing becomes unnecessary.

  In addition, according to the present embodiment, since the sensor chip 100 is used and measurement is performed with near-field light such as evanescent light, the distance for peeling the magnetic fine particles 9 from the sensing area 101 to a range that does not affect the measurement is short. Tesumu. Thereby, the time required for peeling off the magnetic fine particles 9 from the sensing area 101 by applying the upper magnetic field can be shortened. Alternatively, the magnetic fine particles 9 can be peeled from the sensing area 101 to a range that does not affect the measurement by a weaker magnetic field.

Further, according to the present embodiment, since the magnetic field strength can be controlled, the magnetic fine particles 9 that can be measurement noise can be measured from the sensing area 101 without peeling off the magnetic fine particles 9 useful for measurement from the sensing area 101. Can be peeled to a distance that does not affect As a result, the S / N ratio can be improved.
Further, according to the present embodiment, since the magnetic field intensity can be dynamically controlled by the control unit 20, it is possible to perform measurement with higher accuracy.
For example, the magnetic fine particles 9 and the sample solution can be agitated by applying a magnetic field in pulses. Therefore, since the reaction rate between the second substance 13 fixed to the fine particles 12 of the magnetic fine particles 9 and the measurement target substance 14 can be increased, the measurement target substance 14 can be measured with higher accuracy.

If a superparamagnetic material is used as the material of the fine particles 12 in the magnetic fine particles 9, the magnetic fine particles 9 can be easily redispersed when the application of the magnetic field is stopped. For this reason, even when the measurement target substance 14 does not exist in the sample solution, the generation of aggregates of the magnetic fine particles 9 is suppressed, so that generation of measurement errors can be suppressed.
Further, by adding a positive or negative charge to the surface of the fine particles 12 in the magnetic fine particles 9 or adding a dispersant such as a surfactant, the magnetic fine particles 9 are redispersed when the application of the magnetic field is stopped. This makes it easy to reduce the measurement error.

  Further, according to the present embodiment, the naturally settled magnetic fine particles 9 can be pulled back by applying a magnetic field in a direction different from the settling direction. By repeating the natural sedimentation of the magnetic fine particles 9 and the upward pulling back by the magnetic field applying unit 10, the sample solution and the magnetic fine particles 9 can be stirred, so that the measurement target substance 14 (for example, an antigen) contained in the sample solution can be obtained. ) And the magnetic fine particles 9 can be promoted. Therefore, the measurement time can be shortened. In addition, high-precision measurement can be performed even when the measurement target substance 14 has a low concentration.

  In addition, according to the present embodiment, the sensor chip 100 is used to measure the amount and concentration of the measurement target substance 14 using near-field light such as evanescent light. In this case, if the magnetic fine particles 9 having the fine particles 12 having a particle size of 0.05 μm or more and 200 μm or less, preferably 0.2 μm or more and 20 μm or less are used, the light scattering efficiency can be increased. Accuracy can be measured.

[Second Embodiment]
In the first embodiment, the case where a magnetic field is applied in a direction opposite to the direction of the optical waveguide 3 when viewed from the magnetic fine particle 9 is exemplified. However, in the second embodiment, the optical waveguide 3 is viewed from the magnetic fine particle 9. An example in which a magnetic field is applied in both the direction and the opposite direction is illustrated.
FIG. 5 is a schematic diagram for illustrating a measurement system according to the second embodiment. FIG. 5 shows a cross section of the sensor chip 100.
The measurement system 30a according to the second embodiment is obtained by further adding a magnetic field application unit 11 to the measurement system 30 according to the first embodiment shown in FIG.

The magnetic field application unit 11 applies a magnetic field to the sensor chip 100 in the direction of the optical waveguide 3 when viewed from the magnetic fine particles 9. Thereby, the magnetic fine particles 9 can be moved in the direction of the optical waveguide 3.
The magnetic field application unit 11 is provided in the direction in which the optical waveguide 3 exists as viewed from the magnetic fine particles 9. In the present embodiment, the magnetic field application unit 11 is provided in the downward direction of the sensor chip 100.
Similar to the magnetic field application unit 10, the magnetic field application unit 11 may have a permanent magnet or an electromagnet.
The adjustment of the magnetic field intensity using the magnetic field application unit 11 and the dynamic adjustment of the magnetic field intensity can be the same as in the case of the magnetic field application unit 10.

The control unit 20a controls the magnetic field strength of the magnetic field applied by the magnetic field application unit 10, the magnetic field application unit 11, or one of them. In this case, for example, as shown in FIG. 5, a common control unit 20 a and a changeover switch 20 a 1 can be provided for the magnetic field application unit 10 and the magnetic field application unit 11. In addition, independent control units may be provided for the magnetic field application unit 10 and the magnetic field application unit 11, respectively. In addition, a control unit that controls the magnetic field strength at the same time for the magnetic field application unit 10 and the magnetic field application unit 11 may be provided. Moreover, it is good also as the control part 20a which controls so that it may become an appropriate magnetic field strength dynamically by controlling a magnetic field strength as needed.
Further, the control unit 20a may control the timing of applying the magnetic field in each of the magnetic field applying unit 10 and the magnetic field applying unit 11. Thereby, the magnetic field application unit 10 and the magnetic field application unit 11 can alternately apply a magnetic field according to a predetermined condition (for example, a predetermined time or a time during which a predetermined magnetic field is continuously applied).

  Next, together with the operation of the measurement system 30a, a measurement method according to the second embodiment will be exemplified.

FIG. 6 is a schematic process diagram for illustrating the measuring method according to the second embodiment.
6A to 6D illustrate a method of measuring the concentration of the measurement target substance 14 using the measurement system 30a.
6 (a) to 6 (d), the state in the reaction space 102 is represented in order to avoid complication.
6 (a) is the same as FIG. 3 (a), FIG. 6 (c) is the same as FIG. 3 (b), and FIG. 6 (d) is the same as FIG. 3 (c). ). Therefore, the description regarding FIG. 6 (a), (c), (d) is abbreviate | omitted.

FIG. 6B-1 shows a case where the lower magnetic field application by the magnetic field application unit 11 is not performed. Therefore, the magnetic fine particles 9 in the sample solution are settled (natural sedimentation) toward the sensing area 101 by gravity.
6B-2, the lower magnetic field is applied in the settling direction (the direction of the optical waveguide 3, for example, the lower direction in FIG. 6) as viewed from the magnetic fine particles 9 by the magnetic field application unit 11. In FIG. Thereby, the magnetic fine particles 9 are attracted to the sensing area 101 by natural sedimentation due to gravity and attraction by applying a lower magnetic field.
However, as shown in FIG. 6 (b-2), in this state, most of the magnetic fine particles 9 are retained along the lines of magnetic force, so that the binding reaction with the first substance 6 does not proceed. Therefore, as shown in FIG. 6 (c), it is necessary to make the external magnetic field zero once and to proceed the reaction by natural diffusion.
A part of the magnetic fine particles 9 that have settled toward the sensing area 101 in FIGS. 6B-1 and 6B-2 are coupled to the sensing area 101. FIG.

FIG. 7 is a graph for illustrating the operation and effect of the magnetic field application unit.
7A shows a case where only the upper magnetic field is applied by the magnetic field application unit 10. FIGS. 7B and 7C show an application of the lower magnetic field by the magnetic field application unit 11 and an upper magnetic field by the magnetic field application unit 10. Is applied in combination with the application of.
In the case shown in FIG. 7A, the magnetic fine particles 9 are allowed to naturally settle after the sample solution is introduced into the reaction space 102. Then, after the detection signal intensity ratio is reduced to a predetermined value, an upper magnetic field is applied to remove magnetic fine particles 9 that may become noise adsorbed to the sensing area 101. That is, this is the case shown in FIGS. 6 (b-1), (c), and (d).

  7B and 7C, after the sample solution is introduced into the reaction space 102, a lower magnetic field is applied to attract the magnetic fine particles 9 in a direction approaching the sensing area 101. Thereafter, the application of the lower magnetic field is stopped, and the magnetic fine particles 9 are allowed to settle naturally. Then, after the detection signal intensity ratio is reduced to a predetermined value, an upper magnetic field is applied to remove magnetic fine particles 9 that may become noise adsorbed to the sensing area 101. That is, this is the case shown in FIGS. 6 (b-2), (c), and (d).

  As can be seen from FIGS. 7A to 7C, when the lower magnetic field is applied and the magnetic fine particles 9 are attracted in the direction approaching the sensing area 101, the time until the upper magnetic field can be applied is obtained. It can be shortened. Therefore, the measurement time can be shortened.

  As an example, the case of the measurement system 30a shown in FIG. 5 is illustrated, but the present invention is not limited to this. For example, in the case of the measurement system 30b shown in FIG. 8 to be described later, the magnetic fine particles 9 that can become noise adsorbed in the sensing area 101 are applied by applying a lower magnetic field by the magnetic field applying unit 10 as compared with the case of natural sedimentation. It can be removed in a short time. Therefore, the measurement time can be shortened.

Moreover, the lower magnetic field application shown in FIG. 6B-2 and the upper magnetic field application shown in FIG. 6D can be alternately repeated.
For example, after applying the upper magnetic field shown in FIG. 6 (d), the lower magnetic field shown in FIG. 6 (b-2) is applied to attract the magnetic fine particles 9 that are not bound by antigen-antibody reaction or the like. Then, the measurement target substance 14 and the measurement target substance 14 bonded to the second substance 13 fixed to the surface of the fine particle 12 are newly bonded to the first substance 6 fixed to the sensing area 101.

  By repeating this, the number of magnetic fine particles 9 that are not bonded to the sensing area 101 due to an antigen-antibody reaction or the like can be reduced, and the number of magnetic fine particles 9 that are bonded to the sensing area 101 due to an antigen-antibody reaction or the like can be increased. As a result, the S / N ratio can be improved.

  According to the present embodiment, the magnetic fine particles 9 can be attracted to the sensing area 101 by applying a magnetic field to the magnetic fine particles 9 by the magnetic field applying unit 11. Thereby, since it becomes easier to couple the magnetic fine particles 9 to the sensing area 101, the detection sensitivity of the measurement target substance 14 can be improved.

  In addition, by quickly drawing the magnetic fine particles 9 in the direction of the sensing area 101 after introducing the sample solution into the reaction space 102, the time for waiting for the natural precipitation of the magnetic fine particles 9 can be shortened. can do. In addition, the coupling between the magnetic fine particles 9 and the sensing area 101 can be promoted before the reaction or aggregation of the magnetic fine particles 9 proceeds. Thereby, since the utilization factor of the measurement target substance 14 for the binding between the magnetic fine particles 9 and the sensing area 101 can be further increased, higher detection sensitivity can be obtained.

  Furthermore, the specimen solution and the magnetic fine particles 9 can be stirred by moving the magnetic fine particles 9 by both or one of the magnetic field applying unit 10 and the magnetic field applying unit 11. As a result, the antigen-antibody reaction between the measurement target substance 14 (for example, antigen) contained in the sample solution and the magnetic fine particles 9 is promoted, and high detection sensitivity can be measured in a shorter time. Further, the magnetic fine particles 9 can be further stirred by repeatedly applying the upper magnetic field by the magnetic field applying unit 10 and applying the lower magnetic field by the magnetic field applying unit 11. As a result, the opportunity for the magnetic fine particles 9 to bind to the sensing area 101 via the measurement target substance 14 increases, so that the measurement target substance 14 can be detected in a shorter time. In addition, the probability that the magnetic fine particles 9 are bonded to the sensing area 101 can be improved, and the detection sensitivity and measurement accuracy of the measurement target substance 14 can be improved. For example, it is effective when the measurement target substance 14 has a low concentration.

  In the present embodiment, since the magnetic fine particles 9 are stirred using a magnetic field, a manual stirring operation or a stirring mechanism having a pump or the like is not necessary, and a simple measurement and a small measurement system can be realized. For example, if the application of the magnetic field by the control unit 20a is automated, measurement can be performed by only one operation in which the measurer introduces the sample solution into the sensor chip 100.

  Furthermore, if a superparamagnetic material that quickly loses magnetization when the application of the magnetic field is stopped is used as the material of the magnetic fine particles 9, even if the magnetic fine particles 9 aggregate due to magnetization when the magnetic field is applied, It can be redispersed by stopping the application.

  Even if the magnetic fine particles 9 aggregate when the magnetic field is applied, by stopping the application of the magnetic field before the aggregate of the magnetic fine particles 9 reaches the vicinity of the sensing area 101, the aggregate of the magnetic fine particles 9 is regenerated. Can be dispersed. Therefore, the magnetic fine particles 9 can reach the sensing area 101 in a dispersed state. Accordingly, it is possible to prevent an increase in measurement noise due to aggregation of the magnetic fine particles 9.

Further, in order to further improve the redispersibility when the application of the magnetic field is stopped, the surface of the fine particles 12 in the magnetic fine particles 9 may be given a positive or negative charge. Alternatively, a dispersant such as a surfactant may be added to a dispersion medium such as a sample solution.
In addition, according to the present embodiment, the detection sensitivity and measurement accuracy of the measurement target substance 14 can be improved by appropriately controlling the magnetic field strengths of the magnetic field application unit 10 and the magnetic field application unit 11 by the control unit 20a.
In this embodiment, the same effect as that of the first embodiment can be obtained.

[Third embodiment]
In the first and second embodiments, the optical waveguide 3 is provided in the natural sedimentation direction as viewed from the magnetic fine particles 9, but in the third embodiment, in the direction opposite to the natural sedimentation direction as viewed from the magnetic fine particles 9. An optical waveguide 3 is provided.
FIG. 8 is a schematic diagram for illustrating a measurement system according to the third embodiment. In FIG. 8, a cross section of the sensor chip 100 is shown.
As shown in FIG. 8, the measurement system 30b is generally obtained by inverting the measurement system 30a according to the second embodiment illustrated in FIG.

That is, in the measurement system 30b, the magnetic field application unit 10 is disposed below the sensor chip 100, and the magnetic field application unit 11 is disposed above the sensor chip 100. Therefore, in the measurement system 30b, the magnetic field application unit 10 applies the lower magnetic field, and the magnetic field application unit 11 applies the upper magnetic field.
The magnetic field application unit 10 is not always necessary.
The sensor chip 100 is provided upside down with respect to the case illustrated in FIGS. 1 and 5. Therefore, a lid 5c for preventing the sample solution introduced into the reaction space 102 from flowing out is provided.

  The control unit 20b controls the strength of the magnetic field applied by the magnetic field application unit 10 and the magnetic field application unit 11, or one of them. In this case, for example, as shown in FIG. 8, independent control units 20 b 1 and 20 b 2 can be provided for the magnetic field application unit 10 and the magnetic field application unit 11, respectively. Further, a common control unit for the magnetic field application unit 10 and the magnetic field application unit 11 and a changeover switch (not shown) may be provided. In addition, a control unit that controls the magnetic field strength at the same time for the magnetic field application unit 10 and the magnetic field application unit 11 may be provided. Alternatively, the control unit 20b may be configured to control the magnetic field strength as needed to dynamically adjust the magnetic field strength to an appropriate value.

Further, the control unit 20b may control the timing of applying the magnetic field in each of the magnetic field application unit 10 and the magnetic field application unit 11. Thereby, the magnetic field application unit 10 and the magnetic field application unit 11 can alternately apply a magnetic field according to a predetermined condition (for example, a predetermined time or a time during which a predetermined magnetic field is continuously applied).
Since the other configuration is the same as that of the second embodiment, description thereof is omitted.

FIG. 9 is a schematic process diagram for illustrating the measurement method according to the third embodiment.
FIGS. 9A to 9C illustrate a method for measuring the concentration of the measurement target substance 14 using the measurement system 30b.
9A to 9C, the state in the reaction space 102 is represented in order to avoid complications.
The amount and concentration (for example, antigen concentration) of the measurement target substance 14 in the sample solution by measuring the difference in the detection signal intensity ratio in the light receiving element 8 is the same as in the first embodiment. The description is omitted for the same reason.

First, as shown in FIG. 9A, the sample solution is introduced into the reaction space 102. The sample solution is introduced through the hole 5b, and the hole 5b is closed by the lid 5c after the sample solution is introduced.
Here, the sample solution may contain a contaminant 17 that settles under its own weight. Examples of the contaminant 17 include blood cell components in blood. If such a contaminant 17 exists in the vicinity of the sensing area 101, it becomes a scatterer itself and causes measurement noise, or the reaction of the magnetic fine particles 9 binding to the sensing area 101 is hindered. Measurement accuracy may be reduced.

  Next, as shown in FIG. 9B, the magnetic field application unit 11 applies a magnetic field in the direction of the sensing area 101 when viewed from the magnetic fine particles 9. Thereby, the magnetic fine particles 9 are attracted to the sensing area 101. At this time, a first substance 6 (for example, a primary antibody) immobilized on the sensing area 101 and a second substance 13 (for example, a secondary antibody) immobilized on the surface of the microparticles 12 are measured substances 14 (for example, It binds by antigen-antibody reaction via the antigen). Thereby, the magnetic fine particles 9 are coupled to the sensing area 101. At the same time, the sedimentary contaminant 17 moves in the downward direction in FIG. 9B (the direction opposite to the sensing area 101) by its own weight.

Next, as shown in FIG. 9C, the magnetic field applying unit 10 applies a downward magnetic field shown in FIG. 9C. Then, regardless of the antigen-antibody reaction or the like, the magnetic fine particles 9 adsorbed on the sensing area 101 without passing through the measurement target substance 14 move in the settling direction and are removed from the sensing area 101.
Here, even if the application of the magnetic field in the upward direction shown in FIG. 9B is simply stopped using a measurement system in which the magnetic field application unit 10 is not provided, the measurement target substance 14 is not affected by the antigen-antibody reaction or the like. The magnetic fine particles 9 adsorbed on the sensing area 101 without being interposed can be moved downward by their own weight. However, with this method, it is difficult to remove the magnetic fine particles 9 adsorbed on the sensing area 101 when the attractive force of the magnetic fine particles 9 on the sensing area 101 is superior to the downward force corresponding to its own weight. It becomes. In addition, also in the process shown in FIG. 9C, the sedimentary contaminant 17 continues to move downward (in the direction opposite to the sensing area 101) in FIG. 9C due to its own weight.

  Also in the present embodiment, the magnetic field application in the upward direction shown in FIG. 9B and the magnetic field application in the downward direction shown in FIG. 9C or sedimentation due to the weight of the magnetic fine particles 9 may be alternately repeated. Since the effect is the same as that described in the second embodiment, the description thereof is omitted.

According to the present embodiment, the sensing area 101 is positioned above the magnetic fine particles 9, and a magnetic field is applied to the magnetic fine particles 9 by the magnetic field application unit 11. Therefore, at the same time as the magnetic fine particles 9 are attracted to the sensing area 101, the sedimentary contaminant 17 can be allowed to settle downward. Thereby, the contaminant 17 can be naturally moved outside the evanescent light region in the vicinity of the sensing area 101. As a result, the measurement accuracy can be further improved without removing the contaminant 17 by filtration or the like in advance.
In this embodiment, the same effects as those of the first and second embodiments can be obtained.

Next, the magnetic field application unit exemplified in the first to third embodiments will be further described. FIG. 10 is a schematic diagram for illustrating the configuration of the magnetic field application unit.
FIG. 10A is a schematic diagram for illustrating the configuration of the magnetic field application unit, FIG. 10B is a view taken along the line AA in FIG. 10A, and FIG. 10C is a schematic perspective view.
The magnetic field application unit 40 illustrated in FIG. 10 can be used for both the magnetic field application unit 10 and the magnetic field application unit 11 described above.
As shown in FIG. 10, the magnetic field application unit 40 is provided with a coil 41 and a core 42.
The coil 41 has a bobbin 41a and an insulated wire 41b. The bobbin 41a has a cylindrical portion 41a1 around which the insulated wire 41b is wound, and flanges 41a2 provided at both ends of the cylindrical portion 41a1. The bobbin 41a is not always necessary and can be provided as appropriate. For example, the coil 41 can be formed by winding an insulated wire 41 b around the core 42.

The core 42 includes a first core portion 42a provided with the coil 41, a second core portion 42b provided outside the coil 41, one end portion of the first core portion 42a, and a second core portion 42b. A connecting portion 42c for magnetically connecting the one end of the second portion. In the magnetic field application unit 40 illustrated in FIG. 10, two second core portions 42 b are provided at symmetrical positions with the first core portion 42 a interposed therebetween.
In this case, the first core part 42a, the second core part 42b, and the connection part 42c can be separated.
By doing so, it is possible to improve the assemblability when the coil 41 is assembled to the core 42.

Further, as shown in FIG. 10B, the side 42b1 on the gap side (first core part 42a side) of the end surface of the second core part 42b on the sensing area 101 side, or the first core part 42a. A side 42 a 1 on the gap side (second core portion 42 b side) of the end surface on the sensing area 101 side is parallel to the direction in which light propagates inside the optical waveguide 3.
By doing so, since a uniform magnetic field can be applied, the distribution of the magnetic fine particles 9 in the sensing area 101 can be made uniform.
In addition, in the direction in which light propagates inside the optical waveguide 3, the lengths of the end surfaces on the sensing area 101 side of the first core portion 42 a and the second core portion 42 b are equal to or greater than the length of the sensing area 101. Yes.
By doing so, since the magnetic field can be applied to the entire sensing area 101, the magnetic fine particles 9 can be moved in the entire sensing area 101.

The end surface on the sensing area 101 side of the first core portion 42a and the end surface on the sensing area 101 side of the second core portion 42b are flat surfaces.
If the end surface on the sensing area 101 side is a flat surface, the distance between the first core part 42a and the sensing area 101 and the distance between the second core part 42b and the sensing area 101 can be reduced.
Although not shown, the first core portion 42a and the second core portion 42b may have a configuration in which the cross-sectional area decreases as the sensing area 101 is approached.
That is, the 1st core part 42a and the 2nd core part 42b can have a form where the front end side becomes thin.
By doing so, since the magnetic flux can be concentrated, a strong magnetic field can be applied.
Moreover, although illustration is abbreviate | omitted, the 2nd core part 42b can have the form which inclined in the direction in which the edge part by the side of the sensing area 101 adjoins mutually.
By doing so, the generation of the magnetic field can be facilitated.

The core 42 can be formed from a material having a smaller residual magnetization than carbon steel.
For example, the core 42 can be formed from pure iron or the like.
By making the material of the core 42 in this way, it is possible to suppress the influence of the residual magnetic field of the core 42 on the movement of the magnetic fine particles 9 described above when the application of the magnetic field is stopped by the control unit 20 or the like. The core 42 may have a structure in which an insulating coated thin magnetic plate (for example, a silicon steel plate) is laminated in a direction parallel to the magnetic field.
The core 42 may have a structure in which an insulating coated magnetic powder (for example, a fine powder made of a ferromagnetic material such as carbonyl iron) is pressure-molded.
If the structure of the core 42 is as described above, eddy current loss can be reduced.

  In FIG. 10, the coil 41 is provided in the first core portion 42a, but the present invention is not limited to this. For example, the coil 41 may be provided in the second core part 42b, or the coil 41 may be provided in the first core part 42a and the second core part 42b. Moreover, you may provide the coil 41 in the connection part 42c.

Next, a magnetic field application unit according to another embodiment is illustrated.
FIG. 11 is a schematic diagram for illustrating the configuration of the magnetic field application unit.
11A is a schematic diagram for illustrating the configuration of the magnetic field application unit, FIG. 11B is a view taken along the line BB in FIG. 11A, and FIG. 11C is a schematic perspective view.
Note that the magnetic field application unit 50 illustrated in FIG. 11 can be used for both the first magnetic field application unit 10 and the magnetic field application unit 11 described above.
As shown in FIG. 11, the magnetic field application unit 50 is provided with a coil 41 and a core 52.
The coil 41 is the same as that described above, and a description thereof will be omitted.

The core 52 includes two core portions 52a where the coil 41 is provided, and a connection portion 52c that magnetically connects one end portions of the core portion 52a.
In this case, the core portion 52a and the connection portion 52c can be separated.
By doing so, it is possible to improve the assemblability when the coil 41 is assembled to the core 52.
Further, as shown in FIG. 11B, the gap side 52 a 1 on the end surface of the core portion 52 a on the sensing area 101 side is parallel to the direction in which light propagates inside the optical waveguide 3.
By doing so, since a uniform magnetic field can be applied, the distribution of the magnetic fine particles 9 in the sensing area 101 can be made uniform.
In addition, the length of the end surface on the sensing area 101 side of the core portion 52 a is greater than or equal to the length of the sensing area 101 in the direction in which light propagates inside the optical waveguide 3.
By doing so, since the magnetic field can be applied to the entire sensing area 101, the magnetic fine particles 9 can be moved in the entire sensing area 101.

The end surface of the core portion 52a on the sensing area 101 side is a flat surface.
If the end surface on the sensing area 101 side is a flat surface, the distance between the core portion 52a and the sensing area 101 can be reduced.
Although not shown, the core portion 52a may have a configuration in which the cross-sectional area decreases as the sensing area 101 is approached.
That is, the core part 52a can have a form in which the tip end side is narrowed. By doing so, since the magnetic flux can be concentrated, a strong magnetic field can be applied.
Moreover, the core part 52a shall have the form which inclined in the direction in which the edge part by the side of the sensing area 101 adjoins mutually.
By doing so, the generation of the magnetic field can be facilitated.
The material and configuration of the core 52 can be the same as those of the core 42 described above.
For example, the core 52 can be formed of a material having a smaller residual magnetization than carbon steel such as pure iron.
If the material of the core 52 is made in this way, the influence of the residual magnetic field of the core 52 on the movement of the magnetic fine particles 9 described above when the application of the magnetic field is stopped by the control unit 20 or the like can be suppressed. In FIG. 11, the coils 41 are provided in the two core portions 52a, but the present invention is not limited to this. For example, the coil 41 may be provided in one core part 52a, or the coil 41 may be provided in the connection part 52c.

According to the embodiments illustrated above, it is possible to realize a sensor chip, a measurement system, and a measurement method that can perform highly accurate measurement.
As mentioned above, although several embodiment of this invention was illustrated, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, changes, and the like can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and equivalents thereof. Further, the above-described embodiments can be implemented in combination with each other.

  1: substrate, 2a: grating section, 2b: grating section, 3: optical waveguide section, 4: protection section, 5: reaction section, 6: first substance, 7: light source, 8: light receiving element, 9: magnetic fine particles, 10: Magnetic field application unit, 11: Magnetic field application unit, 12: Fine particles, 13: Second substance, 14: Substance to be measured, 17: Contaminant substance, 20: Control unit, 20a: Control unit, 20b: Control unit, 20b1: Control unit, 20b2: control unit, 30: measurement system, 30a: measurement system, 30b: measurement system, 40: magnetization application unit, 50: magnetization application unit, 100: sensor chip, 101: sensing area, 102: reaction space

Claims (9)

And the back Nsachippu,
A magnetic field application unit for applying a magnetic field to the sensor chip;
A light source that emits light toward the sensor chip;
A light receiving element that receives light emitted from the sensor chip;
Equipped with a,
The sensor chip is
An optical waveguide having a sensing area to which a first substance that specifically binds to a measurement target substance is fixed;
A reaction part provided with a recess for introducing the sample solution facing the sensing area;
A second substance that specifically binds to the substance to be measured is fixed, has magnetic properties, and magnetic fine particles having a specific gravity higher than that of the sample solution;
Have
The magnetic field application unit applies the magnetic field having a magnetic field intensity such that the magnetic fine particles are separated from the sensing area by a distance satisfying the following expression.
L> λ / {2π (n ₁ sin ² θ-n ₂ ² ) ^1/2 }
Here, L is the distance that the magnetic fine particles are separated from the sensing area, λ is the wavelength of light used for measurement, n ₁ is the refractive index of the optical waveguide, n ₂ is the refractive index of the dispersion medium that disperses the magnetic fine particles, θ is the total reflection angle. A control unit for controlling the magnetic field application unit;
Wherein the control unit, the measurement system of claim 1, wherein controlling at least one of the length of the timing and the time for applying a magnetic field. The measurement system according to claim 2 , wherein the control unit controls the magnetic field application unit to apply a magnetic field in a pulse shape. The measurement system according to claim 2 , wherein after the sample solution is introduced into the recess, the control unit controls the magnetic field application unit to apply a magnetic field that moves the magnetic microparticles in a direction approaching the sensing area. The measurement system according to claim 1, wherein the magnetic fine particles are held on the surface of the recess in a dry state or a semi-dry state. The measurement system according to claim 1, wherein the magnetic fine particles are held on a surface of the recess facing the sensing area. The measurement system according to claim 5 or 6, wherein the magnetic fine particles are dispersed in the sample solution when the sample solution is introduced. A sample solution containing a substance to be measured and a second substance that specifically binds to the substance to be measured are fixed, and magnetic fine particles having magnetism and higher specific gravity than the sample solution are provided on the sensor chip, and the measurement Bringing the first substance that specifically binds to the target substance into contact with the fixed sensing area;
Applying a magnetic field to the sensor chip;
Measuring the light intensity of light emitted from the sensor chip as a first light intensity before application of the magnetic field;
Measuring the light intensity of the light emitted from the sensor chip as the second light intensity after application of the magnetic field;
Quantifying a measurement target substance based on a difference between the first light intensity and the second light intensity;
Equipped with a,
In the step of applying a magnetic field to the sensor chip, a measurement method of applying the magnetic field having a magnetic field strength such that the magnetic fine particles are separated from the sensing area by a distance satisfying the following expression .
L> λ / {2π (n ₁ sin ² θ-n ₂ ² ) ^1/2 }
Here, L is the distance that the magnetic fine particles are separated from the sensing area, λ is the wavelength of light used for measurement, n ₁ is the refractive index of the optical waveguide, n ₂ is the refractive index of the dispersion medium that disperses the magnetic fine particles, θ is the total reflection angle. The measurement method according to claim 8 , wherein in the step of applying a magnetic field to the sensor chip, a magnetic field is applied in a pulse shape.

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