Apparatus and method for detecting a substance to be measured

Abstract

The purpose of a detecting device for a substance being measured, according to an embodiment of the present disclosure, is to detect a living-organism-related substance such as a bacterium or a true fungus, in a simple manner. A detecting device according to an embodiment of the present disclosure is characterized by including: a container for accommodating a solution, and composite particles in which a substance being measured and a magnetic labeling substance are bound together; a magnetic field applying unit which is provided with a plurality of magnets arranged in positions other than in a lower portion of the container in such a way that magnetic pole surfaces having the same polarity oppose one another, spaced apart from one another by a prescribed spacing, and which applies a magnetic field in such a way that the composite particles are collected together in a prescribed region upon which spatial light is incident, being a region other than a lower region of the container; an imaging unit for imaging the composite particles which have been collected together in the prescribed region, and upon which the spatial light is incident through a region between the opposing magnetic pole surfaces having the same polarity; and a detecting unit for detecting the composite particles on the basis of an image captured by the imaging unit.

Description

[Technical Field]

[0001] The present invention relates to a detection device and a detection method for a substance to be measured. [Background technology]

[0002] There has been a growing need for methods to detect biologically relevant substances, such as viruses, bacteria, and fungi, present in biological sample solutions. Optical detection methods using near-field light are known as methods for detecting biologically relevant substances, such as viruses, that are several hundred nanometers in size (see, for example, Patent Document 1). Here, near-field light refers to light that, when light travels from a medium with a high refractive index to a medium with a low refractive index, if the angle of incidence exceeds a certain critical angle, the light undergoes total reflection at the interface, preventing the light from traveling into the medium with a low refractive index. However, a very thin light, approximately one wavelength of light, seeps into the medium with a low refractive index. Near-field light does not propagate through space and is therefore not diffracted. Therefore, it is used as a means of obtaining information about substances with wavelengths smaller than the diffraction limit of light, which is previously limited by the resolution of microscopes. It is also attracting attention as a method for processing microscopic materials.

[0003] However, because biological substances such as bacteria and fungi are several microns in size, it has been difficult to detect them using optical detection methods that use near-field light. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2017 / 187744 Summary of the Invention

[0005] The object of the detection device for a substance to be measured according to an embodiment of the present disclosure is to simply and easily detect a biologically-related substance such as bacteria or fungi.

[0006] A detection device according to an embodiment of the present disclosure is characterized by comprising: a container for containing a solution and composite particles in which a substance to be measured and a magnetically labeled substance are bound; a plurality of magnets arranged at a position other than the bottom of the container so that their magnetic pole faces of the same polarity face each other at a predetermined distance; a magnetic field application unit that applies a magnetic field so that the composite particles are collected in a predetermined region other than the bottom region of the container where spatial light is incident; an imaging unit that images the composite particles collected in the predetermined region where the spatial light is incident through the region between the opposing magnetic pole faces of the same polarity; and a detection unit that detects the composite particles based on the image captured by the imaging unit.

[0007] In the detection device according to the embodiment of the present disclosure, it is preferable that, among the magnetic pole faces of the multiple magnets, the magnetic pole faces having polarities opposite to those of the opposing magnetic pole faces are positioned outside the peripheral wall of the container.

[0008] In a detection device according to an embodiment of the present disclosure, it is preferable that the position where the magnetic field strength is at its maximum in a plane parallel to the multiple magnets is included in the imaging area of ​​the imaging unit, and that at a position a predetermined distance below the upper end of the container, there is a region where the magnetic field strength is almost constant near the maximum value.

[0009] In the detection device according to the embodiment of the present disclosure, the plurality of magnets are preferably columnar.

[0010] In the detection device according to the embodiment of the present disclosure, the plurality of magnets may have a conical or pyramidal shape.

[0011] In the detection device according to the embodiment of the present disclosure, the plurality of magnets may have an annular shape.

[0012] In the detection device according to the embodiment of the present disclosure, it is preferable that the opposing magnetic poles of the multiple magnets have a tapered shape with a portion cut out on the imaging unit side.

[0013] Preferably, the detection device according to the embodiment of the present disclosure further includes a light-transmitting member that houses the plurality of magnets.

[0014] A detection method according to an embodiment of the present disclosure is characterized in that a solution and composite particles formed by binding a substance to be measured and a magnetically labeled substance are placed in a container, multiple magnets are arranged at positions other than the bottom of the container so that magnetic pole faces of the same polarity face each other at a predetermined distance apart, a magnetic field is applied so that the composite particles are collected in a predetermined region other than the bottom region of the container where spatial light is incident, an image of the composite particles collected in the predetermined region where spatial light is incident is taken through the region between the opposing magnetic pole faces of the same polarity, and the composite particles are detected based on the image captured.

[0015] In a detection method according to an embodiment of the present disclosure, it is preferable that the position where the magnetic field strength is at its maximum in a plane parallel to the multiple magnets is included in the imaging area, and that there is an area on the upper surface of the solution where the magnetic field strength is almost constant near its maximum value.

[0016] According to the detection device for a substance to be measured according to the embodiment of the present disclosure, biologically-related substances such as bacteria or fungi can be detected more easily than when near-field light is used. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a configuration diagram of a detection device for a substance to be measured according to a first embodiment of the present disclosure. [Figure 2] 1 is a side view of a container constituting a detection device for a substance to be measured according to a first embodiment of the present disclosure. [Figure 3] FIG. 1 is a side view of a container constituting a detection device for a substance to be measured according to a first embodiment of the present disclosure, showing a state in which the substance to be measured and a magnetically labeled substance are placed in a solution and stirred to promote the reaction. [Figure 4] 2 is an example of an image of a predetermined region in a solution captured by an imaging section constituting the detection device for a substance to be measured according to the first embodiment of the present disclosure. [Figure 5] FIG. 1 is a side view of a container constituting a detection device for a substance to be measured according to a first embodiment of the present disclosure, showing the state in which the substance to be measured, a magnetically labeled substance, and a fluorescently labeled substance are placed in a solution and stirred to promote the reaction. [Figure 6] 10 is another example of an image of a predetermined region in a solution captured by the imaging section constituting the detection device for a substance to be measured according to the first embodiment of the present disclosure. [Figure 7] FIG. 1 is a configuration diagram of a detection device for a substance to be measured according to a first embodiment of the present disclosure, showing the positional relationship between a magnetic field application unit and a container. [Figure 8] 2(a) to 2(c) are plan views of a plurality of magnets used in a detection device for a substance to be measured according to a first embodiment of the present disclosure. [Figure 9] 2 is a diagram showing the distribution of a magnetic field formed by a plurality of magnets used in the detection device for a substance to be measured according to the first embodiment of the present disclosure. FIG. [Figure 10] 1 is a graph showing the relationship between the distribution of magnetic field strength formed by a plurality of magnets used in the detection device for a substance to be measured according to the first embodiment of the present disclosure and the distance from the magnets. [Figure 11] 1 is a plan view showing the relationship between the regions in which composite particles collected by the detection device for a substance to be measured according to the first embodiment of the present disclosure are distributed and the positions of a plurality of magnets. [Figure 12] 5(a) to 5(c) are plan views of a first modified example of a plurality of magnets used in the detection device for a substance to be measured according to the first embodiment of the present disclosure. [Figure 13] 10(a) and 10(b) are plan views of a second modified example of a plurality of magnets used in the detection device for a substance to be measured according to the first embodiment of the present disclosure. [Figure 14] 10 is a graph showing the relationship between the distribution of magnetic field strength formed by a plurality of magnets in a second modified example used in a detection device for a substance to be measured according to the first embodiment of the present disclosure and the distance from the magnets. [Figure 15] (a) is a cross-sectional view of multiple magnets used in a measurement substance detection device according to a first embodiment of the present disclosure, and (b) is a cross-sectional view of multiple magnets used in a measurement substance detection device according to a second embodiment of the present disclosure. [Figure 16]10A and 10B are a plan view and a cross-sectional view showing a plurality of magnets, a permeable member, and a container used in a detection device for a substance to be measured according to a third embodiment of the present disclosure. [Figure 17] 10A and 10B are cross-sectional views of a plurality of magnets, a permeable member, and a container used in a detection device for a substance to be measured according to a third embodiment of the present disclosure, where (a) is a comparative example assuming that there is no permeable member, and (b) is a cross-sectional view when there is a permeable member. [Figure 18] FIG. 10 is a cross-sectional view of a plurality of magnets, a permeable member, and a container used in a detection device for a substance to be measured according to a third embodiment of the present disclosure, showing a modified example of the container. [Figure 19] 10A and 10B are cross-sectional views of modified examples of multiple magnets, permeable members, and containers used in a detection device for a substance to be measured according to a third embodiment of the present disclosure, where (a) is a comparative example assuming that there is no permeable member, and (b) is a cross-sectional view of a case where there is a permeable member. [Figure 20] FIG. 10 is a configuration diagram of a detection device for a substance to be measured according to a fourth embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, a detection device and a detection method for a substance to be measured according to embodiments of the present disclosure will be described with reference to the drawings. However, it should be noted that the technical scope of the present invention is not limited to these embodiments, but extends to the inventions set forth in the claims and their equivalents.

[0019] [First embodiment] First, a detection device for a substance to be measured according to a first embodiment of the present disclosure will be described. Fig. 1 shows a configuration diagram of a detection device 101 for a substance to be measured according to the first embodiment of the present disclosure. The detection device 101 for a substance to be measured according to the first embodiment has a container 3, a magnetic field application unit 2, and an imaging device 4.

[0020] The container 3 contains a solution 31 and composite particles 54 in which a target substance 51 and a magnetically labeled substance 53 are bonded. The container 3 is not a channel through which a fluid flows, but rather a container for holding a liquid. A biological sample solution, for example, is used as the solution 31. Examples of biological sample solutions include saliva, blood, urine, and sweat. FIG. 2 shows a side view of the container 3 constituting the target substance detection device 101 according to the first embodiment of the present disclosure. FIG. 3 shows a side view of the container 3 constituting the target substance detection device 101 according to the first embodiment of the present disclosure, in which the target substance 51 and the magnetically labeled substance 53 are placed in the solution 31 and stirred to promote the reaction. Preferably, the magnetically labeled substance 53 is bonded to all of the target substance 51 in the solution 31 to form composite particles 54. Furthermore, the target substance 51 and the magnetically labeled substance 53 do not necessarily need to be bonded to each other when they are placed in the container 3. That is, the reaction in which the magnetically labeled substance 53 binds to the substance to be measured 51 may be promoted by the flow of the solution 31 generated by stirring in the container 3, thereby producing composite particles 54. Examples of the substance to be measured 51 include Candida fungus, Escherichia coli, and CRP (C-reactive protein).

[0021] As shown in FIG. 1, the predetermined region 1 is a region other than the lower region of the container 3, where spatial light is incident. In the lower region of the container 3, "other substances" 52, which are substances that do not fall into any of the following categories: a substance to be measured 51, a magnetically labeled substance 53, and a composite particle 54, are precipitated. The other substances 52 include impurities. It is preferable that the predetermined region 1 is a region other than the lower region and does not contain the other substances 52.

[0022] Spatial light (also referred to as "propagating light") refers to general light that propagates through space and does not include localized light such as near-field light. Specifically, spatial light is generally defined as light that does not include near-field light, which exhibits rapid attenuation at a distance of several hundred nanometers to several microns from the source. In this specification, spatial light refers to light that does not include near-field light and does not exhibit rapid attenuation at a distance of several hundred nanometers to several microns from the interface between the container and the solution. In detection methods using near-field light, the detectable region for the substance to be measured is limited to a range on the order of several hundred nanometers from the surface of the solution. Because bacteria and fungi are on the order of several microns, they are difficult to detect using near-field light. Furthermore, detection devices using near-field light have the problem of complex detection substrates and optical systems. In contrast, the detection device for a substance to be measured according to an embodiment of the present disclosure uses spatial light, making it possible to observe substances larger than the wavelength of light. There is no size limit for the substance to be measured 51 as long as it is present in the predetermined region 1. Therefore, the detection device for a substance to be measured according to the embodiment of the present disclosure is capable of detecting bacteria, fungi, and the like having a size on the order of several microns with a simple structure. Spatial light is irradiated toward the predetermined area 1 from an illumination device 6 disposed below the container 3. However, this is not limited to this example, and the illumination device 6 may be disposed on the side or top surface of the container 3. Furthermore, the use of the illumination device 6 is not limited, and natural light may also be used as spatial light.

[0023] The solution 31 in the container 3 may be stirred by shaking the container 3 by hand before setting it in the detection device 101, or by equipping the detection device 101 with a stirring mechanism and stirring inside the detection device 101. When a stirring mechanism is equipped in the detection device 101, a stirring method in which the container 3 is pressed against a rotating disk like a vortex mixer, centrifugal stirring, ultrasonic vibration, etc. can be used. Furthermore, when spatial light is irradiated onto the solution 31, the solution 31 is heated by the light (excitation light, white light) irradiated from the illumination device 6, and convection occurs in the solution 31 due to the heating. Note that when the imaging unit 41 images the solution 31, the solution 31 does not necessarily need to be stirred.

[0024] The magnetic field application unit 2 includes a plurality of magnets (21, 22) arranged at a position other than the bottom of the container 3 (e.g., at the top of the container 3) so that magnetic pole faces (21n, 22n) of the same polarity (e.g., N pole) face each other at a predetermined distance. Here, the state in which the plurality of magnets are "facing" each other refers to a state in which the plurality of magnets face each other, i.e., a state in which the same polarity of the plurality of magnets faces the center. Therefore, this includes not only a state in which the plurality of magnets are symmetrically arranged but also a state in which the plurality of magnets are asymmetrically arranged. Furthermore, it is preferable that the plurality of magnets (21, 22) are arranged on the same plane. The magnets (21, 22) can be, for example, alnico magnets, iron-chromium-cobalt magnets, samarium-cobalt magnets, neodymium magnets, ferrite magnets, etc. The magnetic field application unit 2 applies a magnetic field so as to collect the composite particles 54 in a region other than the bottom region of the container 3, in a predetermined region 1 where spatial light is incident.

[0025] When the magnetic field application unit 2 is placed above the container 3, the composite particles 54, which are magnetically labeled substances to be measured, and the unreacted magnetically labeled substances 53, gather in the predetermined region 1, which is the detection region at the top of the container 3. Meanwhile, the other substances 52 settle to the bottom of the container 3 due to gravity. The reason why the composite particles 54 are gathered in the predetermined region 1, which is a region other than the bottom region of the container 3, is because the other substances 52 that settle in the bottom region of the container 3 may become noise, making detection of the composite particles 54 difficult. The detection device 101 for a substance to be measured according to the first embodiment can separate the predetermined region 1 where the composite particles 54 gather from the bottom region where the other substances 52 settle. Here, in the orientation of the detection device 101 during use, the direction of gravity is referred to as the "downward" direction of the detection device, and the direction opposite to the direction of gravity is referred to as the "upward" direction of the detection device.

[0026] The imaging device 4 includes an imaging unit 41, a detection unit 42, and a control unit 43. Spatial light incident on the predetermined region 1 is reflected or scattered by composite particles 54 in the solution 31 contained in the predetermined region 1, and then enters the imaging unit 41 of the imaging device 4 to form an image. The imaging unit 41 images the composite particles 54 collected in the predetermined region 1 where the spatial light is incident, through the region between the opposing magnetic pole faces (21n, 22n) of the same polarity. The magnetic field application unit 2 is disposed between the container 3 and the imaging unit 41. The imaging unit 41 can image the composite particles 54 collected in the predetermined region 1 without being blocked by the magnetic field application unit 2, and therefore can image the composite particles 54 without moving the magnetic field application unit 2. Therefore, it is possible to apply a magnetic field to the composite particles and image the composite particles 54 while they are collected in the predetermined region.

[0027] The imaging unit 41 has a function of capturing an image of an object and acquiring the image. For example, a device such as a camera or video camera that captures still or moving images can be used as the imaging unit 41. Fig. 4 shows an example of an image 100 of a predetermined region in a solution captured by the imaging unit 41 constituting the detection device 101 for a substance to be measured according to the first embodiment of the present disclosure.

[0028] The detection unit 42 of the imaging device 4 detects the composite particles 54 based on the image 100 captured by the imaging unit 41. The detection unit 42 detects the composite particles 54 from an image including the composite particles 54 and unreacted magnetically labeled substances 53 collected in the predetermined region 1, which is the detection area. Specifically, the magnetically labeled composite particles 54 collected on the upper surface of the container 3 are image-analyzed based on their shape, brightness, and movement due to magnetic fields and convection. Not only the composite particles 54 but also the unreacted magnetically labeled substances 53 are present on the upper surface of the solution 31, but they can be distinguished based on the shape of the analyte 51 and the fact that the analyte 51 and the magnetically labeled substances 53 are bound to each other.

[0029] The control unit 43 of the imaging device 4 controls the entire imaging device 4. In addition, the control unit 43 controls each unit and device other than the imaging device 4 included in the detection device 101 as necessary.

[0030] The imaging device 4 can be, for example, a computer equipped with a CPU and a memory. The memory may be a computer-readable recording medium. The function of the detection unit 42 to detect the composite particles 54 from the image 100 captured by the imaging unit 41 and the function of the control unit 43 are executed by the CPU in the imaging device 4 in accordance with a program pre-stored in the memory in the imaging device 4. Note that the imaging unit 41, the detection unit 42, and the control unit 43 do not necessarily have to be realized by a single computer, but may be realized by multiple computers.

[0031] The magnetically labeled substance 53 specifically binds to the analyte 51. The magnetically labeled substance 53 does not bind to other substances 52. As shown in FIG. 1 , the composite particles 54 are formed by binding the magnetically labeled substance 53 to the analyte 51, and are therefore affected by the magnetic field applied by the magnetic field application unit 2 and move in the direction of arrow A. On the other hand, the other substances 52 do not contain the magnetically labeled substance 53 and therefore settle to the lower region of the container 3 due to gravity acting downward on the container 3 as shown by arrow B. Therefore, the magnetic field applied by the magnetic field application unit 2 causes the composite particles 54 to be collected in a predetermined region 1 other than the lower region of the container 3. Spatial light is incident on this predetermined region 1, and the reflected light, transmitted light, scattered light, etc. from the predetermined region 1 are captured by the imaging unit 41, thereby obtaining an image including the composite particles 54.

[0032] Furthermore, by additionally labeling with a substance having optical characteristics, such as a fluorescent labeling substance, the S / N ratio can be improved. Fig. 5 is a side view of a container 3 constituting an analyte detection device 101 according to a first embodiment of the present disclosure, showing a state in which an analyte 51, a magnetically labeled substance 53, and a fluorescently labeled substance 55 are placed in a solution 31 and stirred to promote a reaction. If the fluorescently labeled substance 55 has the property of specifically binding to the analyte 51, stirring the solution 31 containing the analyte 51, the magnetically labeled substance 53, and the fluorescently labeled substance 55 can form composite particles 54a in which the magnetically labeled substance 53 and the fluorescently labeled substance 55 are bound to the analyte 51.

[0033] 1, a magnetic field can be applied to this solution 31 by placing a magnetic field application unit 2 at a position other than the bottom of the container 3, and composite particles 54a (not shown) can be collected in a predetermined region 1 other than the bottom region of the container 3. Meanwhile, other substances 52 settle due to gravity and are collected in the bottom region of the container 3.

[0034] 6 shows another example of an image of a predetermined region 1 in a solution 31 captured by the imaging unit 41 constituting the detection device 101 for a substance to be measured according to the first embodiment of the present disclosure. The image 100 of the predetermined region 1 captured by the imaging unit 41 includes images of composite particles 54a and magnetically labeled substances 53 collected by the magnetic field application unit 2, but does not include other substances 52. Furthermore, because the composite particles 54a contain fluorescently labeled substances 55, the composite particles 54a can be easily observed by irradiating the predetermined region 1 with fluorescent light.

[0035] Next, the positional relationship between the magnetic field application unit and the container in the detection device for a substance to be measured according to the first embodiment of the present disclosure will be described. FIG. 7 is a configuration diagram of the detection device for a substance to be measured according to the first embodiment of the present disclosure, showing the positional relationship between the magnetic field application unit and the container. FIG. 7 shows an example in which the magnetic pole faces (21n, 22n) of the north poles of two magnets (21, 22) are arranged opposite each other. The magnetic field application unit 2 including the magnets (21, 22) is disposed between the container 3 and the imaging unit 41.

[0036] As shown in Figure 7, a magnetic field is generated around the magnets (21, 22). The graph of magnetic field strength shown at the bottom of Figure 7 shows the magnetic field strength at a position corresponding to the upper surface 31a of the solution 31 in the container 3. As can be seen from the graph of magnetic field strength, the magnetic field strength is highest in the range indicated by W4, and is highest in region 30 of the upper surface 31a near the region sandwiched between the N-pole magnetic pole faces (21n, 22n). Therefore, many composite particles 54 are collected in region 30 where the magnetic field strength is highest, as indicated by the arrows. Therefore, if the region indicated by W3 in Figure 7 is the imaging region, it is preferable that the position where the magnetic field strength is maximum in a plane parallel to the multiple magnets (21, 22) be included in the imaging region W3 of the imaging unit 41.

[0037] However, the magnetic field strength is also strong near the magnetic pole faces (21s, 22s) of the pole (S pole) opposite to the pole (N pole) of the opposing magnetic pole faces (21n, 22n), and the magnetic field strength has peaks (P1, P2), respectively, so that the composite particle 54 is also attracted to the S pole. If the composite particle 54 is attracted to the vicinity of the S pole, it may be blocked by the magnets (21, 22), and the imaging unit 41 may not be able to image the composite particle 54 attracted to the vicinity of the S pole.

[0038] Therefore, in the detection device of this embodiment, it is preferable that, among the magnetic pole faces (21n, 21s, 22n, 22s) of the multiple magnets (21, 22), the magnetic pole faces (21s, 22s) of the opposite poles (S poles) to the poles (N poles) of the opposing magnetic pole faces (21n, 22n) are positioned outside the peripheral wall 3a of the container 3.

[0039] That is, when the width of the peripheral wall 3a of the container 3 is W1 and the distance between the magnetic pole faces (21s, 22s) of the south poles of the two magnets (21, 22) is W2, it is preferable to set the size of the peripheral wall 3a of the container 3 and the positions of the magnetic pole faces (21s, 22s) of the south poles of the magnets (21, 22) so that W2 is greater than W1.

[0040] With this configuration, the composite particles 54 attracted to the south pole are blocked by the peripheral wall 3a of the container 3, and the composite particles 54 can be collected only in the area 30 observed by the imaging unit 41 through the magnetic pole surface (21n, 22n) of the opposing north pole, thereby enabling the composite particles 54 to be detected efficiently.

[0041] Furthermore, it is preferable to configure the magnets (21, 22) so that the positions where the magnetic field strength exhibits the minimum values ​​(Q1, Q2) are outside the peripheral wall 3a of the container 3. If the magnetic field strength exhibits the minimum values ​​(Q1, Q2) inside the peripheral wall 3a of the container 3, the magnetic field strength at the peripheral wall 3a will be greater than the minimum values ​​(Q1, Q2), and there is a risk that the composite particles 54 will remain attracted to the south pole. By configuring the positions where the minimum values ​​(Q1, Q2) are exhibited to be outside the peripheral wall 3a of the container 3, it is possible to prevent the composite particles 54 from being attracted to the south pole.

[0042] Next, the configuration of the multiple magnets used in the detection device for a substance to be measured according to the first embodiment will be described. The multiple magnets are preferably cylindrical. FIGS. 8(a) to 8(c) are plan views of the multiple magnets used in the detection device for a substance to be measured according to the first embodiment of the present disclosure, showing examples in which two, three, and four rectangular parallelepiped magnets are used as the cylindrical magnets. FIGS. 8(a) to 8(c) also show the position of the peripheral wall 3a of the container. However, the present invention is not limited to this example, and cylindrical or prismatic magnets may also be used as the cylindrical magnets.

[0043] 8(a), when two magnets are used, it is preferable to arrange the magnets (21, 22) so that their north pole magnetic faces (21n, 22n) face each other and their south pole magnetic faces (21s, 22s) are positioned outside the peripheral wall 3a of the container. It is also preferable that the two magnets (21, 22) are arranged on the same plane.

[0044] 8(b), when three magnets are used, it is preferable to arrange the magnets (211, 212, 213) so that their north pole magnetic pole faces (211n, 212n, 213n) face each other and are offset by 120 degrees, and their south pole magnetic pole faces (211s, 212s, 213s) are positioned outside the peripheral wall 3a of the container. It is also preferable that the three magnets (211, 212, 213) are arranged on the same plane.

[0045] 8(c), when four magnets are used, it is preferable to arrange the magnets (221, 222, 223, 224) so ​​that the pole faces (221n, 223n) of the north poles (221n, 222n, 223n, 224n) of the magnets (221, 222, 223, 224) are opposite each other and the pole faces (222n, 224n) are opposite each other, with the magnets (221, 222, 223, 224) offset by 90 degrees, and the south pole faces (221s, 222s, 223s, 224s) are positioned outside the peripheral wall 3a of the container. Furthermore, it is preferable that the four magnets (221, 222, 223, 224) are arranged on the same plane.

[0046] Next, the positional relationship between the area surrounded by multiple magnets and the area where composite particles are collected will be described. Fig. 9 shows the distribution of the magnetic field formed by multiple magnets used in the detection device for a substance to be measured according to the first embodiment of the present disclosure. Fig. 9 also shows the magnetic field distribution in the cross section of line DD in Fig. 8(c). It can be seen that a magnetic field of uniform strength is formed near the magnetic pole faces of the N poles of the opposing magnets (221, 223).

[0047] Fig. 10 shows the relationship between the distribution of magnetic field strength generated by multiple magnets used in the detection device for a substance to be measured according to the first embodiment of the present disclosure and the distance from the magnets. Fig. 10 shows the distribution of magnetic field strength in the cross section of line DD in Fig. 8(c), at a distance d from the bottom surfaces of the four magnets (221-224). The distance between opposing magnetic pole faces is 2 mm. In Fig. 10, the horizontal axis represents the distance [mm] from the center position C of the area surrounded by the magnets (221-224), and the vertical axis represents the magnetic field strength [mTesla].

[0048] As shown in FIG. 10, the region with uniform magnetic field strength is widest when the distance d from the bottom surface of the magnets (221-224) is 1 mm. In the example shown in FIG. 10, the width of the region W4 where the magnetic field strength is a predetermined strength, for example, 93 mTesla or more, is approximately 1.6 mm. Therefore, by setting the position of the upper surface 31a of the solution 31 to be 1 mm from the bottom surface of the magnets (221-224), the region with uniform magnetic field strength on the upper surface 31a of the solution 31 is widest, and the composite particles can be uniformly distributed on the upper surface 31a of the solution 31. Here, the upper surface 31a of the solution 31 is positioned at a predetermined distance below the upper end of the container 3. In this way, it is preferable that a region where the magnetic field strength is approximately constant near its maximum value exists at a position a predetermined distance below the upper end of the container 3. If the magnetic field strength is high at a specific position, the composite particles may become densely packed, making it difficult to accurately count the number of composite particles from the captured image. According to the detection device of the embodiment of the present disclosure, the composite particles can be uniformly distributed on the upper surface of the solution, thereby enabling accurate counting of the number of composite particles. Figure 10 shows the distribution of the electric field strength when four magnets are arranged as shown in Figure 8(c). However, this is not limited to this example, and it is preferable to use three or more magnets so that the magnetic field is generated symmetrically about the center of the container when viewed from above.

[0049] FIG. 11 shows the distribution of composite particles observed by the detection device for a substance to be measured according to the first embodiment of the present disclosure and the positional relationship between the multiple magnets. Composite particles 54 are attracted to the position where the magnetic field strength is strongest. If composite particles 54 are collected in region 30 in FIG. 11 according to the magnetic field strength distribution shown in FIG. 10, the spacing between the N-pole magnetic pole faces (221n, 223n) of the opposing magnets (221, 223) and the spacing between the N-pole magnetic pole faces (222n, 224n) of the opposing magnets (222, 224) are both W3 (=2 [mm]), and therefore region 30 where composite particles 54 are collected is included in region 50 surrounded by the opposing magnetic pole faces (221n, 222n, 223n, 224n). In other words, the predetermined spacing W3 is wider than the width W4 at which the magnetic field strength generated by the multiple magnets is equal to or greater than a predetermined strength. With this configuration, the imaging section can capture images of the composite particles 54 collected in the region 30 without being blocked by the magnets (221 to 224).

[0050] Next, a first modified example of the detection device for a substance to be measured according to the first embodiment will be described. Figures 12(a) to 12(c) are plan views of a first modified example of the multiple magnets used in the detection device for a substance to be measured according to the first embodiment of the present disclosure, showing examples in which two, three, and four magnets, each having a conical or pyramidal shape, are used. Figures 12(a) to 12(c) also show the position of the peripheral wall 3a of the container.

[0051] 12(a), when two magnets having a conical or pyramidal shape are used, it is preferable to arrange the magnets (231, 232) so that their north pole magnetic faces (231n, 232n) face each other and their south pole magnetic faces (231s, 232s) are positioned outside the peripheral wall 3a of the container. It is also preferable that the two magnets (231, 232) are arranged on the same plane.

[0052] 12(b), when three conical or pyramidal magnets are used, it is preferable to arrange the magnets (241, 242, 243) so that their north pole magnetic faces (241n, 242n, 243n) face each other and are offset by 120 degrees, and their south pole magnetic faces (241s, 242s, 243s) are positioned outside the peripheral wall 3a of the container. It is also preferable that the three magnets (241, 242, 243) are arranged on the same plane.

[0053] 12(c), when four magnets having a conical or pyramidal shape are used, it is preferable to arrange the magnets (251, 252, 253, 254) so ​​that the north pole magnetic pole faces (251n, 252n, 253n, 254n) of the magnets (251, 252, 253, 254) face each other, and the north pole magnetic pole faces (251n, 253n) face each other, and the magnets (251, 252, 253, 254) are offset by 90 degrees, and the south pole magnetic pole faces (251s, 252s, 253s, 254s) are positioned outside the peripheral wall 3a of the container. Furthermore, it is preferable that the four magnets (251, 252, 253, 254) are arranged on the same plane.

[0054] Next, a second modified example of the detection device for a substance to be measured according to the first embodiment will be described. Figures 13(a) to 13(c) are plan views of a second modified example of the multiple magnets used in the detection device for a substance to be measured according to the first embodiment of the present disclosure, showing examples in which one, two, or four annular magnets are used. Figures 13(a) to 13(c) also show the position of the peripheral wall 3a of the container.

[0055] 13(a), when using a single magnet having an annular shape whose inner and outer peripheral surfaces are magnetized to a single pole, it is preferable to arrange magnet 26 so that, for example, north pole magnetic pole face 26n of magnet 26 is located inside and south pole magnetic pole face 26s of the outer peripheral surface is located outside peripheral wall 3a of the container. Alternatively, magnet 26 may be arranged so that south pole magnetic pole face 26s is located inside and north pole magnetic pole face 26n of the outer peripheral surface is located outside peripheral wall 3a of the container.

[0056] 13(b), when two annular magnets are used, it is preferable to arrange the magnets (261, 262) so that their north pole magnetic faces (261n, 262n) face each other and their south pole magnetic faces (261s, 262s) are positioned outside the peripheral wall 3a of the container. It is also preferable that the two magnets (261, 262) are arranged on the same plane.

[0057] 13(c), when four magnets having an annular shape are used, it is preferable to arrange the magnets (271, 272, 273, 274) so ​​that the magnetic pole faces (271n, 273n) of the north poles (271n, 272n, 273n, 274n) of the magnets (271, 272, 273, 274) are opposite each other and the magnetic pole faces (272n, 274n) are opposite each other, and the magnets (271, 272, 273, 274) are arranged with a 90-degree offset, and the south pole magnetic pole faces (271s, 272s, 273s, 274s) are positioned outside the peripheral wall 3a of the container. Furthermore, it is preferable that the four magnets (271, 272, 273, 274) are arranged on the same plane.

[0058] FIG. 14 shows the relationship between the magnetic field strength distribution generated by multiple magnets and the distance from the magnets in the second modified example used in the detection device for a substance to be measured according to the first embodiment of the present disclosure. FIG. 14 shows the magnetic field distribution in the cross section of the E-E line in FIG. 13(c), illustrating the magnetic field strength distribution at a distance d from the bottom surface of the magnets (271-274). The distance between the opposing N-pole magnetic pole faces (271n, 273n) and (272n, 274n) is 2 mm. As can be seen from FIG. 14, when four annular magnets are used, the area of ​​uniform magnetic field strength is widest when the distance d from the bottom surface of the magnets (271, 272, 273, 274) is 1 mm, just as when rectangular magnets are used. In the example shown in FIG. 14, the width of the area W4 where the magnetic field strength is a predetermined strength, e.g., approximately 280 mTesla, is approximately 1.6 mm. Therefore, the area where the composite particles are collected is included in the area surrounded by the opposing magnetic pole faces (271n, 273n) and (272n, 274n). With this configuration, the imaging unit can capture images of the composite particles without being blocked by the magnets (271 to 274).

[0059] As described above, according to the detection device for the substance to be measured of the first embodiment, the composite particles 54 can be collected in a predetermined area by the magnetic field application unit 2, and then the composite particles can be imaged through the area between the opposing magnetic pole faces of the same polarity, making it possible to easily detect the substance to be measured.

[0060] [Second embodiment] Next, a detection device for a substance to be measured according to a second embodiment of the present disclosure will be described. FIG. 15(a) shows a cross-sectional view of multiple magnets used in the detection device for a substance to be measured according to the first embodiment of the present disclosure. For example, FIG. 15(a) is a cross-sectional view taken along line AA in FIG. 8(a). FIG. 15(b) shows a cross-sectional view of multiple magnets used in the detection device for a substance to be measured according to the second embodiment of the present disclosure. The detection device for a substance to be measured according to the second embodiment differs from the detection device for a substance to be measured according to the first embodiment in that the opposing magnetic poles of the multiple magnets have a tapered shape with a portion cut out on the imaging unit side. The other configurations of the detection device for a substance to be measured according to the second embodiment are the same as those of the detection device for a substance to be measured according to the first embodiment, and therefore detailed description will be omitted.

[0061] As shown in Figure 15(a), when rectangular magnets (21, 22) are used as multiple magnets in the first embodiment, the corner portions (21e, 22e) of each magnet on the imaging unit 41 side overlap with the imaging area when the imaging unit 41 is brought close to the liquid surface L1 of the solution, and the position of the liquid surface L1 that can be imaged by the imaging unit 41 is limited to a distance d1 from the bottom surface of the magnets (21, 22).

[0062] 15(b), in the second embodiment, the opposing magnetic poles of the magnets (21a, 22a) have a tapered shape with portions (21b, 22b) cut out on the imaging unit 41 side. Therefore, a portion of the imaging area of ​​the imaging unit 41 is not blocked by the corners of the magnets, and the imaging area can be lowered to a position L2 on the bottom side of L1. In other words, if the distance between the magnets (21, 22) and the liquid level L2 is d2, d2 can be made larger than d1 (d2>d1).

[0063] In the above explanation, an example was given in which multiple magnets were used, but a tapered shape can also be formed when a single magnet is used as shown in Fig. 13(a). For example, if the cross-sectional view shown in Fig. 15(a) is a cross-sectional view taken along line BB in Fig. 13(a), the inner circumferential side of magnet 26 may have a tapered shape with a portion on the imaging unit 41 side cut out.

[0064] As described above, the detection device for a substance to be measured according to the second embodiment can capture images of a solution in a deeper range. Furthermore, it can prevent the outer periphery of the imaging area from becoming dark due to light being blocked by the corners (21e, 22e).

[0065] [Third embodiment] Next, a detection device for a substance to be measured according to a third embodiment of the present disclosure will be described. Figures 16(a) and 16(b) show a plurality of magnets, a transparent member, and a container used in the detection device for a substance to be measured according to the third embodiment of the present disclosure, with Figure 16(a) being a plan view and Figure 16(b) being a cross-sectional view taken along line FF in Figure 16(a). The detection device for a substance to be measured according to the third embodiment differs from the detection device for a substance to be measured according to the first embodiment in that the magnetic field application unit further includes a transparent member that houses the plurality of magnets. The other configurations of the detection device for a substance to be measured according to the third embodiment are the same as those of the detection device for a substance to be measured according to the first embodiment, and therefore detailed description thereof will be omitted.

[0066] As shown in FIG. 16(a), the light-transmitting member 60 can accommodate, for example, four magnets (221-224). A magnetic field application unit including the four magnets (221-224) is disposed between the container 3 and the imaging unit 41. When the same poles of multiple magnets face each other, a repulsive force is generated, causing the magnets to move outward. The light-transmitting member 60 can accommodate the four magnets (221-224) and fix their respective positions. However, the number and shape of the magnets accommodated in the light-transmitting member 60 are not limited to this example; they may be shaped other than a rectangular parallelepiped, and the number of magnets accommodated may be more than four. Plastic can be used for the light-transmitting member 60. Because the light-transmitting member 60 is light-transmitting, it does not interfere with imaging by the imaging unit 41. In other words, there is no object between the container 3 and the imaging unit 41 that would interfere with imaging by the imaging unit 41.

[0067] Furthermore, as shown in Figure 16(b), when the imaging unit 41 is positioned so as to be in contact with the light-transmitting member 60, if the distance d3 from the bottom surface of the light-transmitting member 60 to the upper surface 31a of the solution 31 is known, the distance d5 (= d3 + d4) from the imaging unit 41 to the upper surface 31a of the solution 31 can be adjusted by the thickness d4 of the light-transmitting member 60.

[0068] Next, the effects obtained by using a light-transmitting member will be described. FIG. 17(b) is a cross-sectional view of a plurality of magnets, a light-transmitting member, and a container used in a detection device for a substance to be measured according to a third embodiment of the present disclosure. FIG. 17(a) is a cross-sectional view of a comparative example in which a light-transmitting member is not used. In FIGS. 17(a) and 17(b), 41a denotes the objective lens of the imaging unit 41, 41b denotes a light beam, 41c denotes the tip of the objective lens, and WD and WD' denote the working distance. The working distance is the distance from the tip 41c of the objective lens used in the imaging unit 41 to the focal point. A magnetic field application unit including magnets (221, 223) is disposed between the container 3 and the imaging unit 41.

[0069] The light-transmitting member 60 has a refractive index n greater than 1 (for example, a refractive index n of 1.5). Here, a comparison is made between a case where the light-transmitting member 60 is present (FIG. 17(b)) and a case where the light-transmitting member 60 is not present (FIG. 17(a)). The working distance WD' when the light-transmitting member 60 is present is longer than the working distance WD when the light-transmitting member 60 is not present. This is because, when the light-transmitting member 60 is present, the optical path length in the light-transmitting member 60 increases from approximately d4 to d4Xn, and the working distance WD increases by d4(n-1), compared to a case where the light-transmitting member 60 is not present.

[0070] 17(b), the distance between the light-transmitting member 60 and the upper surface 31a of the solution 31 can be increased by this increase in working distance, making it difficult for the liquid surface to come into contact with the light-transmitting member 60. This increase can also be used to increase the thickness of the magnet by this increase in working distance, thereby strengthening the magnetic force.

[0071] While the above-described third embodiment of the detection device for a substance to be measured has been described with reference to an example in which the container 3 is open, the container may also be closed. FIG. 18 is a cross-sectional view of a plurality of magnets, a transparent member, and a container used in the detection device for a substance to be measured according to the third embodiment of the present disclosure, illustrating a modified example of the container. A magnetic field application unit including magnets (221, 223) is disposed between the container 300 and the image capture unit 41. The closed container 300 can be filled with a solution 31 without introducing air bubbles. In this case, the upper surface 31a of the solution 31 contacts the upper lid 301 of the container 300. As shown in FIG. 18, when the image capture unit 41 is disposed so as to contact the light-transmitting member 60, the distance d7 (= d4 + d6) from the image capture unit 41 to the upper surface 31a of the solution 31 can be adjusted by adjusting the thickness d4 of the light-transmitting member 60, assuming that the thickness of the upper lid 301 is d6.

[0072] Next, the effect obtained by using a light-transmitting member when the container is sealed will be described. Fig. 19(b) is a cross-sectional view of a modified example of a plurality of magnets, a light-transmitting member, and a container used in a detection device for a substance to be measured according to a third embodiment of the present disclosure. Fig. 19(a) is a cross-sectional view of a comparative example in which it is assumed that there is no light-transmitting member. A magnetic field application unit including magnets (221, 223) is disposed between the container 300 and the imaging unit 41.

[0073] The light-transmitting member 60 has a refractive index n greater than 1 (for example, a refractive index n of 1.5). Here, a comparison is made between a case where the light-transmitting member 60 is present (FIG. 19(b)) and a case where the light-transmitting member 60 is not present (FIG. 19(a)). The working distance WD' when the light-transmitting member 60 is present is longer than the working distance WD when the light-transmitting member 60 is not present. This is because, when the light-transmitting member 60 is present, the optical path length in the light-transmitting member 60 increases from approximately d4 to d4Xn compared to a case where the light-transmitting member 60 is not present, and therefore the working distance WD increases by d4(n-1).

[0074] 19(b), the distance between the light-transmitting member 60 and the upper surface 31a of the solution 31 can be increased by this increase in working distance, making it less likely that the liquid surface will come into contact with the light-transmitting member 60. This increase can also be used to increase the thickness of the magnet by this increase in working distance, thereby strengthening the magnetic force.

[0075] As described above, according to the detection device for a substance to be measured according to the third embodiment, it is possible to easily fix a plurality of magnets.

[0076] [Fourth embodiment] Next, a detection device for a substance to be measured according to a fourth embodiment of the present disclosure will be described. FIG. 20 shows a configuration diagram of a detection device for a substance to be measured according to the fourth embodiment of the present disclosure. A detection device 102 for a substance to be measured according to the fourth embodiment differs from the detection device 101 for a substance to be measured according to the first embodiment in that an imaging device 4 and a magnetic field application unit 2 are disposed on the side of a container 3. The magnetic field application unit 2 is disposed between the container 3 and the imaging unit 41. The other configurations of the detection device for a substance to be measured according to the fourth embodiment are the same as those of the detection device for a substance to be measured according to the first embodiment, and therefore detailed description will be omitted.

[0077] As shown in Figure 20, other substances 52 that are not the object to be measured settle to the bottom of the container 3 due to gravity, but composite particles 54 are collected on the side of the container 3 by the magnetic field application unit 2 and can be imaged by the imaging unit 41.

[0078] According to the detection device for a substance to be measured according to the fourth embodiment, the composite particles 54 can be fixed to the side surface of the container 3, and therefore the composite particles can be easily detected.

[0079] The above description has been given using an example in which other substances, not the substance to be measured, settle in the solution due to gravity. However, the detection device of the embodiment of the present disclosure can also be used when the other substances move in the solution in the opposite direction to gravity. That is, a magnetic field application unit may be installed at the bottom of the container so that the substance to be measured, to which the magnetically labeled substance is bound, moves in the opposite direction to the other substances. By placing the magnetic field application unit in an appropriate position depending on the behavior of the other substances in the solution, the positions of the other substances and the substance to be measured in the solution can be separated.

[0080] Furthermore, in the above embodiment, an example was shown in which the north poles of the multiple magnets were opposed to each other, but the present invention is not limited to this example, and the south poles may be opposed to each other.

[0081] In the above description, an example has been given in which a magnet is used as the magnetic field applying unit 2, but the present invention is not limited to this example, and an electromagnet having an iron core and a coil may also be used.

[0082] According to the detection device and detection method for a substance to be measured according to the embodiments of the present disclosure described above, bacteria, fungi, etc. having a size of several microns in a solution can be detected.

Claims

1. a container for containing a solution and composite particles in which a substance to be measured and a magnetically labeled substance are bound; a magnetic field applying unit including a plurality of magnets arranged at a position other than the bottom of the container so that magnetic pole faces of the same polarity face each other at a predetermined interval, the magnetic field applying unit applying a magnetic field so as to collect the composite particles in a predetermined region other than the bottom region of the container where spatial light is incident; an imaging unit that images the composite particles collected in the predetermined area where spatial light is incident through an area between the opposing magnetic pole faces of the same polarity; a detection unit that detects the composite particle based on the image captured by the imaging unit; and the plurality of magnets are arranged between the imaging unit and the container such that the distance between the magnetic pole faces of the poles opposite to the same poles facing each other is longer than the width of the container, and the distance between the magnetic pole faces of the same poles facing each other is shorter than the width of the container. A detection device characterized by:

2. The detection device of claim 1 , wherein the plurality of magnets are disposed on an upper portion of the container.

3. a position where the magnetic field strength is maximized in a plane parallel to the plurality of magnets is included in an imaging area of ​​the imaging unit; a region where the magnetic field strength is substantially constant near a maximum value exists at a position spaced a predetermined distance downward from the upper end of the container; The detection device according to claim 1 or 2.

4. The detection device according to claim 1 , wherein the plurality of magnets are cylindrical.

5. The detection device according to claim 1 , wherein the plurality of magnets have a conical or pyramidal shape.

6. The detection device according to claim 1 , wherein the plurality of magnets have an annular shape.

7. The detection device according to claim 1 , wherein the opposing magnetic poles of the plurality of magnets have a tapered shape with a portion thereof on the imaging unit side cut out.

8. The detection device according to claim 1 , wherein the magnetic field applying unit further comprises a light-transmitting member that houses the plurality of magnets.

9. 9. The detection device according to claim 1, wherein the plurality of magnets are replaced by a single magnet having an annular shape whose inner and outer peripheral surfaces are magnetized to a single pole.

10. The detection device according to claim 9 , wherein the outer peripheral surface is disposed outside a peripheral wall of the container.

11. The detection device according to claim 9 , wherein the inner circumferential side of the magnet has a tapered shape with a portion thereof on the imaging unit side cut away.

12. a container for containing a solution and composite particles in which a substance to be measured and a magnetically labeled substance are bound; a magnetic field applying unit including a plurality of magnets arranged at a position other than the bottom of the container so that magnetic pole faces of the same polarity face each other at a predetermined interval, the magnetic field applying unit applying a magnetic field so as to collect the composite particles in a predetermined region other than the bottom region of the container where spatial light is incident; an imaging unit that images the composite particles collected in the predetermined area where spatial light is incident through an area between the opposing magnetic pole faces of the same polarity; a detection unit that detects the composite particle based on the image captured by the imaging unit; and the plurality of magnets are disposed between the imaging unit and the container, The opposing magnetic poles of the plurality of magnets have a tapered shape with a portion cut out on the imaging unit side. A detection device characterized by:

13. a container for containing a solution and composite particles in which a substance to be measured and a magnetically labeled substance are bound; a magnetic field applying unit including a plurality of magnets arranged at a position other than the bottom of the container so that magnetic pole faces of the same polarity face each other at a predetermined interval, the magnetic field applying unit applying a magnetic field so as to collect the composite particles in a predetermined region other than the bottom region of the container where spatial light is incident; an imaging unit that images the composite particles collected in the predetermined area where spatial light is incident through an area between the opposing magnetic pole faces of the same polarity; a detection unit that detects the composite particle based on the image captured by the imaging unit; and the plurality of magnets are disposed between the imaging unit and the container, Instead of the plurality of magnets, one magnet having an annular shape whose inner and outer peripheral surfaces are magnetized to a single pole is used, The inner circumferential side of the magnet has a tapered shape with a portion thereof on the imaging unit side cut out. A detection device characterized by:

14. A solution and composite particles in which a substance to be measured and a magnetically labeled substance are bound are placed in a container; a plurality of magnets are arranged at positions other than the bottom of the container so that magnetic pole faces of the same polarity face each other at a predetermined interval, and a magnetic field is applied so that the composite particles are collected in a predetermined region other than the bottom region of the container where spatial light is incident; an imaging unit capturing an image of the composite particles collected in the predetermined region where spatial light is incident through a region between the opposing magnetic pole faces of the same polarity; Detecting the composite particles based on the captured image; the plurality of magnets are arranged between the imaging unit and the container such that the distance between the magnetic pole faces of the poles opposite to the same poles facing each other is longer than the width of the container, and the distance between the magnetic pole faces of the same poles facing each other is shorter than the width of the container. A detection method characterized by:

15. A solution and composite particles in which a substance to be measured and a magnetically labeled substance are bound are placed in a container; a plurality of magnets are arranged at positions other than the bottom of the container so that magnetic pole faces of the same polarity face each other at a predetermined interval, and a magnetic field is applied so that the composite particles are collected in a predetermined region other than the bottom region of the container where spatial light is incident; an imaging unit capturing an image of the composite particles collected in the predetermined region where spatial light is incident through a region between the opposing magnetic pole faces of the same polarity; Detecting the composite particles based on the captured image; the plurality of magnets are disposed between the imaging unit and the container, The opposing magnetic poles of the plurality of magnets have a tapered shape with a portion cut out on the imaging unit side. A detection method characterized by:

16. A solution and composite particles in which a substance to be measured and a magnetically labeled substance are bound are placed in a container; a plurality of magnets are arranged at positions other than the bottom of the container so that magnetic pole faces of the same polarity face each other at a predetermined interval, and a magnetic field is applied so that the composite particles are collected in a predetermined region other than the bottom region of the container where spatial light is incident; an imaging unit capturing an image of the composite particles collected in the predetermined region where spatial light is incident through a region between the opposing magnetic pole faces of the same polarity; Detecting the composite particles based on the captured image; the plurality of magnets are disposed between the imaging unit and the container, Instead of the plurality of magnets, one magnet having an annular shape whose inner and outer peripheral surfaces are magnetized to a single pole is used, The inner circumferential side of the magnet has a tapered shape with a portion thereof on the imaging unit side cut out. A detection method characterized by:

17. a position where the magnetic field strength is maximized in a plane parallel to the plurality of magnets is included in the imaging area; a region where the magnetic field intensity is substantially constant near a maximum value exists on the upper surface of the solution; 17. The method of claim 14.

Images