Magnetic detection device for living cells

Abstract

Magnetic detection device for living cells [Solution] The present invention is configured with a tip diameter of the nT meter sensor element of 15μm or less, which is comparable to the size of a cell (20μm), and a grid sensor with a diameter of 5mm to match the size of a cell body (several mm). This allows the device to detect the minute magnetic field of 0.1nT to 50nT emitted by cells, contributing to research on the activity of the cell body.

Description

[Technical field]

[0001] For physical health, it is common to diagnose the condition by attaching electrodes to the body to measure electrocardiograms and electroencephalograms. In order to obtain more detailed information about the inside of the body, there are attempts to diagnose the condition by measuring magnetocardiograms and magnetoencephalograms using highly sensitive magnetic sensors.

[0002] In basic medical research, electrodes are inserted into cell bodies and the activity of the cells is studied by measuring the electrical potential waveforms generated by the cells. Changes in the electrical potential of the cell body cause current to flow and generate a magnetic field. It is known from Non-Patent Document 1 that the magnetic field changes correspond to changes in electrical potential (Figure 1), and there are hopes for the development of a biological cell magnetic detection device that can perform non-contact measurements. A cell is about 20 μm in size, and the cell body is about a few millimeters in size. In order to detect the nT-level minute magnetic fields emitted from the cell body, it is hoped that a small-sized, highly sensitive magnetic sensor (hereinafter referred to as an nT sensor) will be developed. Here, it is preferable to be able to identify and measure the magnetic field emitted by the entire cell body and a specific cell that emits a strong magnetic field within it.

[0003] Patent Document 1 and Non-Patent Document 1 report that a magnetic sensor with an element length of 10 mm (the magnetic sensor used in this case is an MI sensor) is used to measure biomagnetism by arranging the element longitudinally parallel to a container containing a cell body (Figure 2), and that the magnetic signal corresponds to the electrical signal. Although the magnetic field signal emitted by the cell body as a whole can be measured, the cell that is emitting a strong magnetic field or its position cannot be identified. In addition, the distance between the cell body placed in the container and the sensor is large, at 0.6 mm to 1 mm, making it difficult to accurately measure the magnetic field emitted by the cell body.

[0004] In Patent Document 2, the length of the element is 2 mm or less (the magnetic sensor used in this case is a GSR sensor), the cell body and the sensor are arranged in parallel (Figure 3), and the distance between them is kept to 0.3 mm or less, thereby increasing the measurement sensitivity. The elements are arranged in a grid pattern to measure the magnetic field emitted by the entire cell body, and the image is processed to identify cells that are emitting a strong magnetic field. However, since the elements are arranged parallel to the bottom of the container, it is difficult to identify specific cells that are about 20 μm apart. There is a limit to this arrangement, as shortening the length of the element reduces the sensitivity of the nT sensor.

[0005] However, Patent Document 2 discloses a structure in which the element and the bottom of the container are arranged vertically (Figure 4). The specification comments that this structure is possible, but does not provide any further information. Judging from the specification and the drawings, it can be inferred that the thickness of the container bottom is 160 μm, the sensor covering is 80 μm, and the gap between the element tip and the sensor tip is 60 μm, making the total distance 300 μm. This distance matches the 300 μm or less specified in the claims. If the length of the magnetic wire is 1 mm, and the measurement position of the element is considered to be the center, it is another 500 μm away from the bottom, for a total of 800 μm, and it is expected that the magnetic field cannot be measured with high accuracy.

[0006] In Patent Document 3, the amorphous magnetic wire is changed to a Co-based alloy to improve the sensitivity of the sensor, but in the present invention, it is preferable to employ a small, highly sensitive sensor with as good performance as possible.

[0007] For these reasons, with current technology, it is difficult to detect the magnetic field emitted by cells with a size of about 20 μm and cell bodies with a size of several mm. The present invention solves this problem by devising the arrangement of the nT sensor and the positional relationship between the cell body and the sensor element, based on the premise of an nT sensor that has already been developed and is commercially available. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2011-89894 A [Patent Document 2] Patent No. 7329783 [Patent Document 3] Patent No. 7474968 [Non-patent literature]

[0009] [Non-Patent Document 1] Shinsuke Nakayama, Tsuyoshi Uchiyama nature SCINTIFIC REP0RTS pp1~9 (06.March,2015) Summary of the Invention [Problem to be solved by the invention]

[0010] In order to detect the magnetic field emitted by a 20 μm-sized cell, the inventors came up with the idea of ​​placing the element vertically on the bottom of a container, taking into consideration that the magnetic wire, which is the magnetic sensitive body of the nT sensor (hereinafter referred to as the sensor), has a diameter of 5 μm and a length of 1 mm, and investigated the possibility of doing so. The anticipated problems in this case are: The first issue is the relationship between the distance between the cell body and the tip of the sensor. The magnetic field emitted by the cell body attenuates in proportion to the square of the distance. We investigated how far the distance between the cell and the sensor element should be.

[0011] The second issue is that the sensor uses a calibration curve of magnetic field strength and sensor output voltage by comparing the magnetic field at the center of the sensor element length with the sensor output voltage, and this is used as the detection power of the sensor. If the sensor element is arranged vertically, the distance between the center of the element and the cell body will increase, and it is expected that the magnetic field strength to be measured will decrease and the measurement accuracy will deteriorate. Therefore, the sensor length must be determined by understanding the relationship between the length of the sensor element and the detection power of the sensor.

[0012] The third challenge is to devise a device that, if it is confirmed that biomagnetism can be detected with a single sensor element, can arrange them in a grid pattern, determine the magnetic field distribution emanating from cell bodies, and identify cells that are emitting strong magnetic fields. [Means for solving the problem]

[0013] The inventors fabricated prototypes of a GSR sensor type nT sensor that uses Co alloy-based amorphous wire with sensor element lengths ranging from 1 mm to 10 mm, and measured the magnetic fields emitted from cell bodies with sizes ranging from 1 mm to 20 mm. The results show that the strength of the measured magnetic field drops significantly when the distance between the cell and the sensor element is increased, as shown in Figure 5. To maintain high accuracy, the distance between the two must be kept at least 100 μm or less.

[0014] Based on the above research results, the present inventors have devised a container with a bottom thickness of 100 μm or less in order to minimize the distance between the two.

[0015] In addition, the magnetic wire, which is the magnetosensitive body, was lengthened to the tip of the sensor element (Fig. 6), and the sensor element was placed at the tip of the nT sensor (Fig. 7). This makes it possible for the tip of the magnetic wire to come into contact with the bottom of the container, with the distance between them being only the thickness of the bottom of the container. In addition, since the Co-based alloy has excellent corrosion resistance, it is possible to leave the tip of the magnetic wire exposed as it is. This solved the first problem.

[0016] Regarding the second issue, the measurement value of the nT sensor is determined by measuring the magnetic field at the center of the sensor element. If the length of the sensor element is 1 mm, the center of the sensor element is 0.5 mm away from the bottom of the container, which may result in a significant drop in the measurement value and may make it difficult to obtain high accuracy.

[0017] Therefore, we changed the length of the sensor element from 1 mm to 10 mm and measured by contacting the sensor element with the bottom of the container. We found that when the length was 2 mm or less, the magnetic field at the bottom of the container and the measured value were almost the same (line (a) in Figure 8). For comparison, if we assumed that the magnetic field was being measured at the center of the sensor element, the value would be as shown by line (b) in Figure 8, but the actual measured value was significantly larger. In other words, they discovered that if a sensor element with a length of 2 mm or less is used and the sensor element is brought into contact with the bottom of the container and the magnetic field is measured by touching it vertically to the bottom of the container, the magnetic field strength at the point of contact can be measured. This confirmed the advantage of placing the sensor element vertically against the bottom of the container and measuring in the vertical direction.

[0018] Regarding the third issue, since the coil width of the sensor element is about 40 μm, it is theoretically possible to arrange the sensor elements with intervals of 0.1 mm or more. Regarding the element grid, the proof-of-principle type has one sensor element placed so that it is in vertical contact with the center of the bottom of the container (Fig. 9), and the grid size is increased to 3.5 mm x 3.5 mm, with 2 x 2 elements, 3 x 3 elements, 4 x 4 elements, and up to a maximum of 20 x 20 elements (Fig. 10). The more the number of grid elements increases, the more accurate the distribution of the magnetic field emitted by the cell body and the identification of specific cells that are emitting strong magnetic fields become.

[0019] The present invention is a device (Fig. 11) that has been realized by setting the diameter of the magnetic wire of the sensor element of the GSR sensor type nT sensor to 15 μm or less, the length to 2 mm, arranging the end of the magnetic wire at the end of the sensor, arranging the sensor element perpendicular to the bottom of the container, and setting the thickness of the bottom of the container to 0.1 mm or less, thereby minimizing the distance between the cell body and the end of the sensor element. Furthermore, the device is capable of arranging the sensor elements in a grid pattern, grasping the magnetic field emitted from the entire cell body, and identifying the cell that emits a strong magnetic field from the entire cell body. Effect of the Invention

[0020] This invention makes it possible to measure the biomagnetic field emitted from the cell body, and compared to the current method of inserting electrodes to test the activity of the cell body, this invention is non-contact, so the test can be greatly simplified. It is also possible to identify cells of 20 μm in size that emit strong magnetic fields. It is considered to be a particularly effective device in basic research in the medical field that studies the activity of cells. [Brief description of the drawings]

[0021] [Figure 1] FIG. 11 is a diagram showing the correspondence between a change in electric potential and a change in magnetic field. [Diagram 2] This is a diagram showing a parallel arrangement of a cell body and a magnetic sensor consisting of a sensor element with a length of 10 mm. [Diagram 3] FIG. 1 shows a parallel arrangement of sensor elements of a magnetic microscope. [Figure 4] FIG. 1 shows a vertical arrangement of sensor elements of a magnetic microscope. [Diagram 5] FIG. 13 is a diagram showing the effect of the distance between a cell and a sensor element on the strength of a magnetic field. [Figure 6] FIG. 13 is a diagram showing a magnetic wire disposed at the tip of a sensor element. [Figure 7] FIG. 13 shows the sensor element being placed in contact with the bottom of the container. [Figure 8] FIG. 13 illustrates the effect of the length of the sensor element on the measured magnetic field. [Figure 9] FIG. 1 shows a single sensor element placed in contact with the center of the bottom of a container. [Figure 10] FIG. 1 shows a plurality of sensor elements (grid elements) arranged in a grid shape in contact with the center of the bottom of a container. [Figure 11] FIG. 1 is a conceptual diagram of a biological cell magnetic detection device. BEST MODE FOR CARRYING OUT THEINVENTION

[0022] The biological cell magnetic detection device of the present invention comprises: The device includes a container for holding a cell body and a micromagnetic field measuring device. the container part includes a non-magnetic container for containing the cell body and a container fixing part for fixing the container; The container is in the shape of a cylindrical mortar, the tip of the mortar has a diameter of 5 mm or less, and the thickness of the bottom of the tip is 0.1 mm or less, The micro-magnetic field measuring device comprises an nT sensor having a detection power of 1 nT or less, a magnetic sensitive body of a sensor element of the nT sensor is made of a Co-based amorphous magnetic wire, the size of which is 15 μm or less in diameter and 2 mm or less in length, and the tip of the magnetic sensitive body is disposed at the tip of the nT sensor, The nT sensor, which is made of the sensor element, is installed on an nT sensor fixing part installed below the container, the nT sensor fixing portion includes a position adjustment portion that adjusts the position of the sensor element and the tip end of the container, the position adjustment unit includes an angle adjustment mechanism that adjusts the perpendicularity of the length direction of the sensor element and the bottom surface of the container so that they face each other perpendicularly, and a position adjustment mechanism that adjusts the position of the sensor element and the position of the tip of the container using a moving device on the XY axes (center) and the Z axis (distance); It is characterized by detecting magnetic signals emitted from the cell body.

[0023] The sensor element of the nT sensor is also characterized by being composed of a plurality of grid elements.

[0024] Furthermore, each device is characterized by being made of non-magnetic materials.

[0025] The biological cell magnetic detection device will be described in detail below mainly with reference to FIG. The biological cell magnetic detection device 3 comprises a container portion 31 for containing a cell body and a micromagnetic field measurement device 32 arranged below the container portion 31.

[0026] <Container part> The container part 41 consists of a non-magnetic container 411 and a container fixing part 312 that fixes the container 411. The container 411 is filled with a cell body 4110, which is an aggregate of biological cells (hereinafter referred to as cells), and its culture solution 4111. The container fixing part 412 fixes the container 411 so that it does not move during measurement by the micro magnetic field measuring device 42.

[0027] As illustrated in FIGS. 9 to 11, the shape of the container 411 is a cylindrical mortar shape with a wide upper part and a narrowed tip part forming a small bottom. This is to facilitate putting the cell body 4110 and the culture solution 4111 into the container and to concentrate the cell body 4110 for measurement at the center of the bottom of the tip part. Therefore, the size of the cylindrical mortar-shaped container 411 is preferably about 10 mm to 15 mm in diameter at the upper part and 5 mm or less in diameter at the tip part. The thickness of the bottom of the tip part is 0.1 mm or less. In this way, a cell body 3110 of about several millimeters will exist on the bottom with a thickness of 0.1 mm or less. The material of the container 411 includes non-magnetic metal materials represented by SUS304, organic materials such as plastics and hard vinyl.

[0028] <Micro magnetic field measuring device> The micro magnetic field measuring device 42 consists of an nT sensor 421 and an nT sensor fixing part 422 that fixes the nT sensor 421. The nT sensor 421 has a detection output of 1 nT or less. The magnetosensitive body of the sensor element 4211 of the nT sensor 421 is made of a Co-based amorphous magnetic wire. The diameter of the magnetic wire is 15 μm or less, preferably 2 μm to 10 μm. Its length is 2 mm or less, preferably 0.5 mm to 1.8 mm. The coil pitch is from 0.5 μm to 3 μm. The number of coil turns is from 80 to 1000. This is because when using one sensor element 3211 or forming a grid element, the diameter and length of the magnetic wire are determined corresponding to the number of grid elements. The tip of the magnetosensitive body is arranged at the tip part of the nT sensor 421, which is the tip of the sensor element 4211.

[0029] <nT sensor fixing part> The nT sensor fixing part 422 is placed below the container 411 and fixes the nT sensor 421 made of a sensor element 4211. In addition, a position adjustment part 422 that adjusts the position between the sensor element 4211 and the tip of the container 411 is provided.

[0030] <Position adjustment part> The position adjustment section 422 is made up of an angle adjustment mechanism 4221 and a position adjustment mechanism 4222 . The angle adjustment mechanism 4221 is a mechanism for adjusting the perpendicularity so that the longitudinal direction of the sensor element 4211 faces perpendicularly to the bottom surface of the container 41. By making the angle perpendicular, the magnetic signal emitted from the cell body 4110 can be detected with high accuracy. The position adjustment mechanism 4222 is a mechanism that moves the position of the sensor element 4211 and the position of the tip of the container 41 to the container center by the XY axes, and adjusts the element tip to contact or a small amount by the Z-axis (distance) moving device. The cell body 4110 is located on the bottom of the container 31, and the sensor element 4211 is in contact with it across a bottom that is 0.1 mm thick or less.

[0031] This allows detection of a magnetic signal from a single cell with a size of 20 μm that constitutes the cell body 4110 with a size of several mm and the tip of the magnetic wire with a size of 15 μm or less, which is the magnetic sensitive body of the sensor element 4211, and obtains a magnetic field measurement distribution of the cell body 4110 from the magnetic signal of each cell. It is also possible to identify cells that emit a strong magnetic field from the entire cell body. Furthermore, by using the sensor elements 4211 arranged in a grid, it becomes possible to quickly, easily and accurately measure the distribution of the magnetic field emitted by the cell bodies and to identify specific cells that are emitting strong magnetic fields.

[0032] The performance of the minute magnetic field detection device of the present invention is such that it can measure a minute magnetic field of 0.1 nT to 50 nT emitted by a cell body of several mm in size, and can measure the activity of the cell body in a non-contact manner.

[0033] As described above, since the measurement is performed on a minute magnetic field, that is, biological cell magnetism, it goes without saying that not only the container but also each device and member is made of a non-magnetic material. EXAMPLES

[0034] The biomagnetic detection device of this embodiment and the detection results are as follows. The container is a cylindrical mortar made of vinyl resin, with a diameter of the cylindrical part being 12 mm, a total height being 18 mm, a diameter of the tip of the mortar being 4 mm, and a thickness of the bottom being 0.05 μm. The container fixing part is made of a hard plastic material, has a diameter of 30 mm, a height of 15 mm, and has a cylindrical mortar-shaped hole in the center so that the container can be fixed. The container is inserted and fixed in this hole. The nT sensor of the micro-magnetic field measuring device has a detection power of 0.2 nT. The magnetic sensitive body of the sensor element is a Co-based amorphous magnetic wire with a diameter of 5 μm and a length of 1 mm. The nT sensor fixing part is installed below the container, to which the nT sensor is fixed and which is equipped with a position adjustment part consisting of an angle adjustment mechanism and a position adjustment mechanism. The container fixing part and the nT sensor fixing part are assembled using a non-magnetic jig.

[0035] A 2.0 mm cell body consisting of cells with sizes of 15 μm to 20 μm was placed in the container of this biomagnetic detection device together with culture fluid, and measurements were made, and magnetic signals emitted from the cell body were detected. By processing this magnetic signal, it was possible to measure the distribution of the magnetic field emitted by the cell body and identify specific cells that were emitting a strong magnetic field. [Industrial Applicability]

[0036] Considering the advantages of the cell magnetic detection method, which can measure the activity of living cells without contacting them, compared to the previous method of electrical palpation, in which electrodes are inserted and fluctuations in electrical potential are observed, it is expected that this method will be widely used in basic research in the medical field. [Explanation of symbols]

[0037] 1: Sensor element 12: Magnetic sensitive body (magnetic wire) 2: Sensor device 20: Cell body 201:Culture solution 202:Bottom of container 21: Sensor element 22: nT sensor 23: Wiring on the board 3: 1 sensor element 31: Container 311: Bottom of container 32: Sensor element 4: Biocell magnetic detection device 41: Container part 411: Container 4110: Cell body 4111:Culture solution 412: Container fixing part 42: Micromagnetic field measuring device 421: nT sensor 4211: Sensor element 422:Position adjustment section 4221: Angle adjustment mechanism 4222:Position adjustment mechanism

Claims

1. A biological cell magnetic detection device including a container for holding a cell body and a micromagnetic field measuring device, the container part includes a non-magnetic container for containing the cell body and a container fixing part for fixing the container; The container has a cylindrical mortar shape, the tip of the mortar has a diameter of 5 mm or less, and the thickness of the bottom of the tip is 0.1 mm or less. The micro-magnetic field measuring device comprises an nT sensor having a detection power of 1 nT or less, a magnetic sensitive body of a sensor element of the nT sensor is made of a Co-based amorphous magnetic wire, the size of which is 15 μm or less in diameter and 2 mm or less in length, and the tip of the magnetic sensitive body is disposed at the tip of the nT sensor, The nT sensor, which is made of the sensor element, is installed on an nT sensor fixing part installed below the container, the nT sensor fixing portion includes a position adjustment portion that adjusts the position of the sensor element and the tip end of the container, the position adjustment unit includes an angle adjustment mechanism that adjusts the perpendicularity of the longitudinal direction of the sensor element and the bottom surface of the container so that the longitudinal direction of the sensor element faces perpendicularly to the bottom surface of the container, and a position adjustment mechanism that adjusts the position of the sensor element and the position of the tip of the container using a moving device on the XY axes (center) and the Z axis (distance); A biological cell magnetic detection device that detects magnetic signals emitted from a cell body.

2. In claim 1, A biological cell magnetic detection device, characterized in that the sensor element of the nT sensor is composed of a plurality of grid elements.

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