Cell excitation device

Abstract

To apply magnetic stimulation to cells with high spatial resolution while sufficiently suppressing the magnetic signals generated at a signal source.SOLUTION: A cell excitation device comprises: a magnetic field source; a substrate placed on the magnetic field source and having a second surface, different from the first surface facing the magnetic field source, to place cells on the surface, or a surface placed to face the cells; a magnetic concentrator array composed of multiple magnetic concentrators placed two-dimensionally within the substrate; each of the multiple magnetic concentrators having magnetic anisotropy, when the magnetic field source is placed on an extension of the easy axis of magnetization of the magnetic concentrator, a magnetic circuit being formed in which a magnetic signal generated by the magnetic field source is output to the second surface via the magnetic concentrator.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a cell excitation device. [Background technology]

[0002] It has been known that applying magnetic stimulation to cells can induce various reactions, such as inducing cell differentiation and promoting or inhibiting cell proliferation. Furthermore, while electrical stimulation, which uses electrodes to connect cells to the outside world, carries the risk of generating harmful ions and environmental pollution, magnetic stimulation minimizes stress on living organisms without harming healthy tissues, making it a relatively safe method useful in medical fields. For example, Patent Document 1 discloses a method for inducing morphological and functional changes in cells, i.e., cell differentiation, by culturing cells in a continuous pulsed magnetic field. Patent Document 2 discloses a non-invasive method for magnetically stimulating neurons in a target region of the human brain by electromagnetic induction using a changing magnetic field. Furthermore, Non-Patent Document 1 discloses that by using magnetoelectric nanoparticles (MENPs), a wirelessly applied magnetic field is converted into a dipole electric field (magnetoelectric effect), and the electric field from the nanoparticles can affect the membrane potential and generate action potentials. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-161323 [Patent Document 2] Japanese Patent Application Publication No. 7-143971 [Non-patent literature]

[0004] [Non-Patent Document 1] E. Zhang et al., "Magnetic-field-synchronized wireless modulation of neural activity by magnetoelectric nanoparticles" Brain Stimulation, vol.15, (2022) 1451-1462 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the above-described conventional cell magnetic stimulation methods have two problems. First, the magnetic signal to be generated in the signal source for cell stimulation is relatively large. Specifically, the configuration described in Patent Document 1, in which a signal source for magnetic stimulation is placed outside the culture vessel in which the target cells grow, and the configuration described in Patent Document 2, in which a signal source for magnetic stimulation is placed outside the skull in which the target neurons reside, require a signal source that generates a magnetic signal at the Tesla level (0.1 T to 10 T). The need for such a large magnetic field has led to an increase in the size and complexity of the signal source device configuration. Specifically, because the magnetic signal attenuates in proportion to the cube of the distance between the signal source and the cells, taking signal attenuation into consideration, a larger magnetic field generator (coil) is required for a signal source placed outside the culture vessel or the skull. Furthermore, because such a signal source requires a large current to be applied, the use of a cooling system further increases the size and complexity of the device.

[0006] Second, there is the problem that the spatial resolution of magnetic field stimulation is insufficient, at the centimeter level. For example, to apply magnetic field stimulation to a localized region at the single-cell level, a spatial resolution of several tens of micrometers is required. In contrast, in Patent Document 1, magnetic field stimulation is applied widely within the cell culture vessel from outside the vessel, making it difficult to achieve high spatial resolution. Patent Document 2 describes magnetic stimulation of neurons and neuronal cell bodies, but does not address higher spatial resolution that would enable magnetic field stimulation at the single-cell level. Furthermore, in Non-Patent Document 1, although individual magnetoelectric nanoparticles (MENPs), which are magnetoelectric transducers, are considered to be sufficiently small compared to the size of the cells to be stimulated, applying magnetic field stimulation from outside the cell culture vessel causes magnetoelectric conversion by MENPs throughout the area to which the magnetic stimulation is applied, making it impossible to stimulate individual cells with sufficient spatial resolution. As described above, there has been insufficient research into technologies that apply magnetic stimulation to cells with high spatial resolution while sufficiently suppressing magnetic signals generated by the signal source. [Means for solving the problem]

[0007] The present disclosure can be realized in the following forms. (1) According to one aspect of the present disclosure, there is provided a cell excitation device, comprising: a magnetic field generating source that generates a magnetic field; a substrate disposed on the magnetic field generating source, the substrate having a second surface, different from a first surface facing the magnetic field generating source, on which a cell is to be placed or a surface facing a cell; and a magnetic concentrator array constituted by a plurality of magnetic concentrators two-dimensionally arranged within the substrate, each of the plurality of magnetic concentrators having magnetic anisotropy; When the magnetic field source is positioned on an extension of the easy axis of magnetization of the magnetic material concentrator, a magnetic circuit is formed in which a magnetic signal generated by the magnetic field source is output to the second surface via the magnetic material concentrator. According to this embodiment of the cell excitation device, when the magnetic field source is arranged on an extension of the easy axis of magnetization of the magnetic material concentrator, a magnetic circuit is formed in which a magnetic signal generated by the magnetic field source is output to the second surface of the substrate via the magnetic material concentrator. Therefore, the magnetic signal generated by the magnetic field source is efficiently input to and converged by the magnetic material concentrator, and output to the cells arranged on the second surface of the substrate on an extension of the easy axis of the magnetic material concentrator. As a result, the magnetic signal that should be generated by the magnetic field source can be suppressed. Furthermore, because the magnetic material concentrators are arranged two-dimensionally, by appropriately setting the size of the magnetic material concentrators and the distance between adjacent magnetic material concentrators depending on the cells to be stimulated, it is possible to apply stimulation with improved spatial resolution. (2) The cell excitation device of the above aspect may further include a current supply unit that supplies a current for generating a magnetic field to the magnetic field generation source, and the magnetic field generation source may be configured with a coil or a coil and a magnetic core. With this configuration, it is possible to efficiently stimulate the cells to be stimulated while suppressing the AC current supplied from the AC current supply unit to the magnetic field generation source. (3) The cell excitation device of the above aspect may include a plurality of the magnetic field generating sources, the plurality of magnetic field generating sources having a two-dimensional array structure, each of the magnetic field generating sources constituting a magnetic field generating unit together with the corresponding magnetic material concentrator, and the magnetic field generating source in each of the magnetic field generating units may be arranged on an extension of the magnetic easy axis of the corresponding magnetic material concentrator. With this configuration, cells to be stimulated can be arranged on an extension of the magnetic easy axis, thereby enabling efficient cell stimulation. (4) In the cell excitation device of the above aspect, each of the plurality of magnetic concentrators may be arranged so that the direction perpendicular to the surface of the substrate is the axis of easy magnetization, and each of the magnetic field generating sources may be arranged so as to overlap with the corresponding magnetic concentrator in the direction perpendicular to the surface of the substrate. With this configuration, cells to be stimulated can be efficiently stimulated by arranging the cells on the substrate at a position perpendicular to the surface of the substrate with respect to the magnetic concentrator. (5) The cell excitation device of the above embodiment may further include a moving mechanism that horizontally moves at least one of the magnetic field source and the substrate in two dimensions so that the magnetic field source is positioned on an extension of the magnetic easy axis of each of the magnetic concentrators. With this configuration, cells can be efficiently stimulated by moving the magnetic field source so that it is positioned on an extension of the magnetic easy axis of the magnetic concentrator corresponding to the cell to be stimulated. (6) In the cell excitation device of the above aspect, each of the plurality of magnetic concentrators may be embedded in the substrate or may be disposed so as to penetrate the substrate, thereby simplifying the structure of the cell excitation device. (7) In the cell excitation device of the above aspect, each of the plurality of magnetic concentrators may be made of a soft magnetic material having one or more of shape magnetic anisotropy, induced magnetic anisotropy, stress magnetic anisotropy, and magnetocrystalline anisotropy, which allows the magnetic concentrator to easily converge the magnetic flux. (8) In the cell excitation device of the above aspect, each of the plurality of magnetic concentrators may have shape magnetic anisotropy and may be formed in a shape selected from the group consisting of a cylindrical shape, a rectangular parallelepiped shape, a capsule shape whose cross section parallel to the central axis is elliptical, a pyramidal shape, and a conical shape. With this configuration, the magnetic concentrator can be configured with a relatively simple structure. (9) In the cell excitation device of the above aspect, each of the plurality of magnetic material concentrators may have magnetic anisotropy and a closed-circuit magnetic domain structure at the outer periphery including the surface of the magnetic material concentrator, which suppresses the intrusion of magnetic flux from directions other than the easy axis of magnetization related to the magnetic anisotropy. With this configuration, the magnetic material concentrator suppresses the intrusion and exit of magnetic flux from directions other than the easy axis of magnetization, so that the magnetic flux in the easy axis direction is concentrated, thereby further improving the spatial resolution when stimulating cells. (10) In the cell excitation device of the above aspect, the magnetic concentrator and at least a part of the magnetic field source provided corresponding to the magnetic concentrator may be integrally formed, which simplifies the overall structure of the cell excitation device. (11) In the cell excitation device of the above aspect, a coating layer containing a cell adhesive component may be provided on the second surface of the substrate so as to cover an area including the area where the plurality of magnetic concentrators are formed, and the diameter of a cross section of each of the plurality of magnetic concentrators parallel to the surface direction of the substrate may be 5 μm or more and 1000 μm or less. With this configuration, it becomes easy to apply a magnetic field stimulus to each individual cell cultured on the second surface of the substrate. (12) In the cell excitation device of the above aspect, the magnetic concentrator may be exposed on the second surface of the substrate, and the difference in height between the second surface of the substrate and the portion of the magnetic concentrator exposed on the second surface may be 10 μm or less. With this configuration, when cells cultured on the second surface of the substrate are to be stimulated, cell culture on the second surface can be performed more effectively. (13) The cell excitation device of the above aspect may further include a shielding portion on the second surface of the substrate, protruding from the second surface and surrounding the entire area where the plurality of magnetic concentrators are arranged, to prevent the passage of magnetic flux. With this configuration, environmental noise from around the cell excitation device can be blocked, and a desired magnetic field stimulus can be applied accurately to the cells arranged on the second surface of the substrate. (14) In the cell excitation device of the above aspect, a shielding portion may be provided on the second surface of the substrate, protruding from the second surface, for each magnetic concentrator, surrounding the area where the magnetic concentrator is arranged, to prevent the passage of magnetic flux. This configuration can improve the reliability of blocking environmental noise from around the cell excitation device and further improve the accuracy of cell stimulation. (15) In the cell excitation device of the above aspect, magnetic sensor elements may be arranged on the first surface side of the substrate in place of the magnetic field source, corresponding to some of the plurality of magnetic concentrators, and the magnetic sensor elements and the magnetic concentrators provided corresponding to the magnetic sensor elements may be arranged to form a magnetic circuit in which a magnetic signal is input to the magnetic sensor elements via the magnetic concentrators. With this configuration, cells on the second surface of the substrate can be stimulated with high spatial resolution and precision using the magnetic field source and the magnetic concentrators, and magnetic signals from the cells on the second surface of the substrate can be detected with high spatial resolution and precision using the magnetic sensor elements and the magnetic concentrators. (16) The cell excitation device of the above aspect may further include a magnetoelectric element on the second surface of the substrate that converts a magnetic signal into an electric signal, and at least one of the cells and the magnetoelectric element may be arranged on the second surface of the substrate on an extension of the easy axis of magnetization of the magnetic concentrator. With this configuration, the magnetic signal from the magnetic field generating source that is concentrated by the magnetic concentrator is converted into an electric signal in the magnetoelectric element, so that an electric stimulus can be applied to cells present in the vicinity of the magnetoelectric element by using the magnetic signal from the magnetic field generating source. The present disclosure can be realized in various forms other than those described above, for example, a method for manufacturing a cell excitation device, a method for inducing cell differentiation, a method for regulating cell proliferation, a method for stimulating cells, etc. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is an explanatory diagram showing a schematic configuration of a cell excitation device according to a first embodiment. [Figure 2] FIG. 2 is a perspective view showing a part of the appearance of the cell excitation device. [Figure 3] FIG. 4 is an explanatory diagram showing the magnetization curve of a cylindrical magnetic concentrator 42. [Figure 4] 10 is a flowchart showing a method for manufacturing a cell excitation device. [Figure 5] FIG. 3 is an enlarged cross-sectional view showing a portion of a substrate including a magnetic concentrator. [Figure 6] 10 is a flowchart showing a method for manufacturing a cell excitation device. [Figure 7] FIG. 10 is an explanatory diagram showing the state of a magnetic signal when a magnetic concentrator is provided. [Figure 8] FIG. 10 is an explanatory diagram showing the state of a magnetic signal when a magnetic concentrator is not provided. [Figure 9] 10A to 10C are explanatory diagrams showing substrates with magnetic concentrators of different shapes; [Figure 10] 10A to 10C are explanatory diagrams showing substrates with magnetic concentrators of different shapes; [Figure 11]10A to 10C are explanatory diagrams showing substrates with magnetic concentrators of different shapes; [Figure 12] FIG. 10 is an explanatory diagram showing the configuration of a magnetic concentrator according to a third embodiment. [Figure 13] FIG. 2 is an explanatory diagram showing a magnetization curve for a magnetic concentrator. [Figure 14] FIG. 10 is an explanatory diagram showing a schematic configuration of a cell excitation device according to a fourth embodiment. [Figure 15] FIG. 10 is an explanatory diagram showing a schematic configuration of a cell excitation device according to a fifth embodiment. [Figure 16] FIG. 2 is a perspective view showing a part of the appearance of the cell excitation device. [Figure 17] FIG. 10 is an explanatory diagram showing the state of a magnetic signal when a magnetic concentrator is provided. [Figure 18] FIG. 10 is an explanatory diagram showing the state of a magnetic signal when a magnetic concentrator is not provided. [Figure 19] FIG. 10 is an explanatory diagram showing a schematic configuration of a cell excitation device according to a sixth embodiment. [Figure 20] FIG. 13 is an explanatory diagram showing a schematic configuration of a cell excitation device according to a seventh embodiment. [Figure 21] FIG. 13 is an explanatory diagram showing a schematic configuration of a cell excitation device according to an eighth embodiment. [Figure 22] FIG. 13 is an explanatory diagram showing a schematic configuration of a cell excitation device according to a ninth embodiment. [Figure 23] FIG. 20 is an explanatory diagram showing a schematic configuration of a cell excitation device according to a tenth embodiment. [Figure 24] FIG. 1 is an explanatory diagram showing a photograph of a cell excitation device. [Figure 25] FIG. 4 is an explanatory diagram showing the results of examining the surface roughness of the second surface of the substrate. [Figure 26] FIG. 4 is an explanatory diagram showing the results of examining the surface roughness of the second surface of the substrate. [Figure 27] FIG. 10 is an explanatory diagram showing the results of fluorescence observation of cells after culturing. DETAILED DESCRIPTION OF THE INVENTION

[0009] A. First embodiment: (A-1) Cell excitation device configuration: FIG. 1 is an explanatory diagram showing the schematic configuration of a cell excitation device 10 according to a first embodiment of the present disclosure, and FIG. 2 is a perspective view showing a portion of the exterior of the cell excitation device 10. In FIGS. 1 and 2, as well as in FIGS. 9 to 11, 14 to 16, and 19 to 23 described below, mutually orthogonal X, Y, and Z axes are shown to identify directions. The X, Y, and Z axes shown in each figure each indicate the same direction. In this specification, the Z axis indicates the vertical direction, and the X and Y axes indicate the horizontal direction. The vertical and horizontal directions are specified for convenience of explanation and may not coincide with the orientation of the cell excitation device 10 when in use. In FIG. 2 and the perspective views shown in FIGS. 9 to 11, 16, and 23 described below, internal structures that cannot be seen from the outside are indicated by dashed lines. Note that FIGS. 1 and 2 show the layout of each component only and do not accurately represent the dimensional ratios of each component.

[0010] As shown in FIG. 1, the cell excitation device 10 includes a magnetic field source array 20 having a plurality of magnetic field sources 22, a substrate 30 arranged on the magnetic field source array 20, and a magnetic concentrator array 40 consisting of a plurality of magnetic concentrators 42 arranged within the substrate 30.

[0011] The magnetic field source array 20 is composed of multiple magnetic field sources 22 arranged two-dimensionally on the XY plane. The magnetic field generated by the magnetic field sources 22 may be either an AC magnetic field or a DC magnetic field. FIG. 1 shows the magnetic field sources 22 as AC electromagnets that generate an AC magnetic field. The magnetic field sources 22 that generate an AC magnetic field may be composed of a coil or a coil and a magnetic core. In this case, the cell excitation device 10 may further include an AC current supply unit 24 that supplies AC current to each magnetic field source 22 for magnetic field generation. The AC current supply unit 24 may be configured as a device including, for example, a power supply unit for supplying AC current to each magnetic field source 22 and a control unit for controlling the AC current supplied from the power supply unit to each magnetic field source 22. The AC current supplied to each magnetic field source 22 by the AC current supply unit 24 may be, for example, a sinusoidal AC current, a square wave AC current, or a pulse signal. 1, a DC current supply unit may be provided instead of the AC current supply unit 24 as a current supply unit that supplies a current for generating a magnetic field to the magnetic field generation source 22, and the magnetic field generation source 22 may be a DC electromagnet that generates a DC magnetic field. Furthermore, when the magnetic field generation source 22 that generates a DC magnetic field is provided, the magnetic field generation source 22 may be configured by a permanent magnet.

[0012] The substrate 30 is formed into a plate-like shape and includes a magnetic concentrator array 40 therein, which is composed of a plurality of magnetic concentrators 42 arranged two-dimensionally on the XY plane. The substrate 30 is made of a non-magnetic material, preferably a highly transparent material. There are no particular restrictions on the material from which the substrate 30 is made, as long as it is a non-magnetic material. However, for ease of microscopic observation, it is preferable to make the substrate 30 from glass or resin. Furthermore, the substrate 30 does not need to be a single member made of a solid material; for example, the substrate 30 may have thin-film members on the surface layers of its upper and lower surfaces, with the rest of the surface layers being composed of a vacuum layer or air layer.

[0013] The magnetic concentrator 42 is made of a magnetic material (ferromagnetic material). The material constituting the magnetic concentrator 42 is preferably a soft magnetic material with high magnetic permeability. The material constituting the magnetic concentrator 42 can be, for example, nickel (Ni), cobalt (Co), iron (Fe), NiFe-based soft magnetic material, CoNiFe-based soft magnetic material, CoTaZr-based soft magnetic material, or a combination of multiple materials selected from these, or may be an amorphous magnetic material.

[0014] The magnetic concentrator 42 of this embodiment has magnetic anisotropy. Specifically, the magnetic concentrator 42 is made of a soft magnetic material having one or a combination of shape magnetic anisotropy, induced magnetic anisotropy, stress magnetic anisotropy, and magnetocrystalline anisotropy, and has an easy axis, which is a specific direction in which magnetization is easy. As an example, FIGS. 1 and 2 show a cylindrical magnetic concentrator 42 having at least shape magnetic anisotropy.

[0015] 3 is an explanatory diagram showing the magnetization curve of a cylindrical magnetic concentrator 42 having shape magnetic anisotropy. In the graph of FIG. 3, the horizontal axis represents the magnetic field H (Oe), and the vertical axis represents the magnetization strength M (emu / cm 3 1, the vertical direction (Z-axis direction) is the easy axis direction, and the horizontal direction (direction parallel to the XY plane) is the hard axis direction.

[0016] 2, the plurality of magnetic concentrators 42 included in the cell excitation device 10 of this embodiment have a two-dimensional array structure arranged within the substrate 30. The magnetic concentrators 42 may be arranged, for example, so as to penetrate the substrate 30, or may be arranged so as to be embedded within the substrate 30. FIG. 2 shows how cylindrical magnetic concentrators 42 are provided, penetrating the highly transparent substrate 30.

[0017] As shown in FIG. 1 , the cell excitation device 10 of this embodiment is provided with a magnetic material concentrator 42 corresponding to each magnetic field generation source 22. Hereinafter, the combination of the magnetic field generation source 22 and the corresponding magnetic material concentrator 42 will also be referred to as a magnetic field generation unit 12. In each magnetic field generation unit 12, the magnetic field generation source 22 is disposed on an extension of the easy axis of magnetization of the magnetic material concentrator 42, forming a magnetic circuit in which a magnetic signal generated by the magnetic field generation source 22 is output to the surface of the substrate 30 via the magnetic material concentrator 42. Specifically, the magnetic signal generated by the magnetic field generation source 22 is converged by the magnetic material concentrator 42 and output to a second surface 34 of the substrate 30, which is different from the first surface 32 facing the magnetic field generation source 22. In particular, since the easy axis of the magnetic material concentrator 42 of this embodiment is the Z-axis direction, the magnetic field generation source 22 is disposed directly below the magnetic material concentrator 42 so as to overlap with the magnetic material concentrator 42 in the Z-axis direction (the direction perpendicular to the surface of the substrate 30). The direction of the magnetic signal output from the magnetic concentrator to the second surface of the substrate 30 is the easy axis direction in the magnetic concentrator .

[0018] When exciting cells using the cell excitation device 10 (applying a magnetic field stimulus to the cells), the cells to be excited may be placed on the second surface 34 of the substrate 30. FIG. 1 shows a state in which a cell 50 cultured on the second surface 34 is the excitation target. When the cell 50 to be excited is present on the magnetic concentrator 42, i.e., on an extension of the easy axis of the magnetic concentrator 42, the magnetic signal generated by the magnetic field generating source 22 is converged by the magnetic concentrator 42 and output from the second surface 34, stimulating the cell 50 located on an extension of the easy axis of the magnetic concentrator 42.

[0019] In the magnetic concentrator 42, which has magnetic anisotropy, magnetic flux easily passes through the easy axis direction inside the magnetic material, resulting in high magnetic permeability. Other hard axes are difficult to magnetize. Therefore, by arranging the cell 50, the magnetic concentrator 42, and the magnetic field source 22 in this order on the easy axis of the magnetic concentrator 42, the magnetic signal generated by the magnetic field source 22 can be converged within the magnetic concentrator 42 and focused in a single direction in which the cell 50 is located. In this way, the magnetic signal generated by the magnetic field source 22 is converged in the magnetic concentrator 42, thereby reducing the magnitude of the magnetic signal to be generated by the magnetic field source 22. In general, magnetic signals have the property of attenuating in proportion to the cube of the distance depending on the distance from the signal source. Therefore, from the viewpoint of suppressing attenuation of the magnetic signal output from the magnetic field source 22 to the cell 50, it is desirable to shorten the distance between the cell 50 and the magnetic concentrator 42 and the distance between the magnetic concentrator 42 and the magnetic field source 22, and it is even more desirable for them to be in contact with each other.

[0020] The size of each magnetic material concentrator 42 and the distance between adjacent magnetic material concentrators 42 may be appropriately set depending on the desired spatial resolution when exciting cells 50 using the cell excitation device 10. For example, when using cylindrical magnetic material concentrators 42 as shown in FIGS. 1 and 2, the diameter of the magnetic material concentrators 42 is preferably 1 mm or less, more preferably 100 μm or less. Furthermore, the distance between adjacent magnetic material concentrators 42 is preferably 1 mm or less, more preferably 100 μm or less. With this configuration, sufficient spatial resolution can be achieved even when stimulating cells of typical size having a diameter of approximately several tens of μm. Furthermore, the length of the magnetic material concentrators 42 can be, for example, 0.1 mm or more and 2 mm or less.

[0021] (A-2) Manufacturing method of cell excitation device: FIG. 4 is a flowchart showing a first manufacturing method as an example of a manufacturing method for the cell excitation device 10 of this embodiment. When manufacturing the cell excitation device 10 according to the first manufacturing method, first, a plurality of concentrator members for forming the magnetic material concentrator 42 are prepared (step T100). The concentrator members may be made of the magnetic material already described as a constituent material of the magnetic material concentrator 42, and may be shaped (e.g., cylindrical) according to the desired shape of the magnetic material concentrator 42. Then, the prepared concentrator members are subjected to a heat treatment such as magnetic annealing (step T110). The heat treatment performed in step T110 can be a treatment to improve the magnetic properties of the concentrator members or a treatment to remove and alleviate residual stress caused by processing (e.g., pressing, welding, bending, cutting, etc.) performed to fabricate the concentrator members. Magnetic annealing is a heat treatment performed primarily for the purposes of improving the magnetic properties of the concentrator members and removing and alleviating the residual stress in the concentrator members. Magnetic annealing also has the effect of increasing the magnetic permeability of the magnetic material. The heat treatment performed in step T110 may be, in addition to or instead of the magnetic annealing described above, a magnetic field heat treatment, tension heat treatment, or Joule annealing (current annealing). Magnetic field heat treatment generates magnetic anisotropy, including induced magnetic anisotropy and stress magnetic anisotropy, thereby improving the magnetic properties.

[0022] In addition to steps T100 and T110, a substrate plate for forming the substrate 30 is prepared (step T120). The substrate plate may be a plate-shaped member made of the material already described as the constituent material of the substrate 30. Then, the prepared substrate plate is drilled to form a plurality of holes arranged in an array (arranged two-dimensionally) (step T130). The positions of the arrayed holes formed in step T130 correspond to the positions where the magnetic concentrators 42 should be arranged on the substrate 30 of the cell excitation device 10. The size of the holes formed in step T130 may be slightly larger than the cross-sectional size of the concentrator member that has undergone step T110.

[0023] Thereafter, the concentrator members that have undergone step T110 are inserted into each of the holes formed in the substrate plate in step T130 (step T140). Then, the substrate plate and the concentrator members are bonded together using an adhesive to integrate them (step T150). After step T150, the surface of the substrate plate integrated with the concentrator members is polished (step T160), and further integrated with the magnetic field generation source array 20 (step T170), completing the cell excitation device 10.

[0024] FIG. 5 is an enlarged cross-sectional view of a portion of the substrate 30 including the magnetic material concentrator 42 in the cell excitation device 10 obtained by the first manufacturing method shown in FIG. 4 . As shown in FIG. 5 , the inner wall of a hole formed in the substrate 30 is bonded to the magnetic material concentrator 42 with an adhesive 35. In the cell excitation device 10, the magnetic material concentrator 42 generally has a higher thermal expansion coefficient than the substrate 30. Therefore, it is desirable to select an adhesive 35 that has a high ability to absorb stress generated between the substrate 30 and the magnetic material concentrator 42 during thermal expansion of the magnetic material concentrator 42, taking into account the thermal expansion coefficient of the magnetic material concentrator 42, for example. The adhesive 35 may be selected appropriately depending on the material of the magnetic material concentrator 42. Examples of adhesives that can be used for the adhesive 35 include silica-based adhesives, alumina-based adhesives, magnesia-based adhesives, and α-cyanoacrylate-based adhesives. Because the cell excitation device 10 uses cells 50 as stimulation targets, it is desirable for the adhesive 35 to be biocompatible.

[0025] 6 is a flowchart showing a second manufacturing method as an example of a manufacturing method of the cell excitation device 10 of this embodiment. In FIG. 6, steps common to those in FIG. 4 are assigned the same step numbers. When manufacturing the cell excitation device 10 according to the second manufacturing method, as in the first manufacturing method, first, multiple concentrator members are prepared (step T100), and the prepared concentrator members are subjected to heat treatment such as magnetic annealing (step T110). In addition to steps T100 and T110, a substrate plate is prepared (step T120).

[0026] Then, in the second manufacturing method, without processing the substrate plate, each concentrator member is heated to a temperature equal to or higher than the melting point of the material constituting the substrate plate. Then, each concentrator member is pressed against the respective location on the substrate plate where the magnetic concentrator 42 is to be arranged, and the concentrator member penetrates the substrate plate while melting the substrate plate with the heat of the concentrator member (step T145). Then, the surface of the substrate plate integrated with the concentrator member is polished (step T160), and further integrated with the magnetic field source array 20 (step T170), completing the cell excitation device 10.

[0027] The polishing process in step T160 shown in FIGS. 4 and 6 may be performed as appropriate to achieve a desired surface roughness for the substrate plate integrated with the concentrator member, depending on the purpose and mode of use of the cell excitation device 10, or the cells 50 to be stimulated. For example, when culturing cells 50 on the second surface 34 of the substrate 30 in the fabricated cell excitation device 10, it is desirable to minimize the surface roughness of the substrate 30 so as not to hinder the growth of the cultured cells. From this perspective, for example, it is desirable that the height difference between the highest and lowest points on the second surface 34 be 10 μm or less. Furthermore, when the end of the magnetic concentrator 42 is exposed on the second surface 34 of the substrate 30, it is desirable that the height difference between the second surface 34 of the substrate 30 and the exposed portion of the magnetic concentrator 42 on the second surface 34 (the height difference between the highest and lowest points) be 10 μm or less.

[0028] Furthermore, when cells 50 are cultured on the second surface 34 of the substrate 30 in the cell excitation device 10 as described above, the second surface 34 may be subjected to a surface treatment suitable for cell culture after the polishing process in step T160 of FIGS. 4 and 6 . Specifically, for example, the entire second surface 34, including the area where the magnetic concentrator 42 is to be disposed, may be coated with a cell adhesion coating agent. Examples of the cell adhesion coating agent that can be used include extracellular matrices such as collagen, laminin, fibronectin, and proteoglycan. This configuration facilitates the growth of cultured cells on the substrate 30, enabling longer-term culture. Furthermore, the coating process may involve coating with a resin that readily adheres to cells, in addition to the biomolecules described above. In this case, a thin film having a thickness of about 1 nm to 100 μm may be formed using, for example, polystyrene, polyethylene terephthalate, polycarbonate, polymethyl methacrylate, polydimethylsiloxane, cycloolefin polymers and copolymers thereof, or biocompatible metal compounds such as titania, which are used in tissue culture plates and cover glasses for cell observation.

[0029] Furthermore, when cells 50 are cultured on the second surface 34 of the substrate 30 of the cell excitation device 10 as described above, the diameter of the cross section of each of the multiple magnetic concentrators 42 parallel to the surface direction of the substrate 30 is preferably 5 μm or more and 1000 μm or less. Setting the diameter to 1000 μm or less facilitates application of magnetic stimulation to individual cells. From this perspective, the diameter is more preferably 800 μm or less, and even more preferably 500 μm or less. However, the diameter may exceed 1000 μm and may be appropriately set depending on the type of cultured cells. Furthermore, setting the diameter to 5 μm or more facilitates the manufacture of the cell excitation device 10.

[0030] Whether the first or second manufacturing method described above is adopted, the cell excitation device 10 having an array structure can be manufactured while maintaining the magnetic domain structure and magnetic properties of the components constituting the magnetic material concentrator 42. Furthermore, the second manufacturing method eliminates the need for drilling in step T130, simplifying the manufacturing process and eliminating the need for adhesive 35. However, in the second manufacturing method, the temperature to which the concentrator components are heated in step T145 must be set sufficiently lower than the Curie temperature of the magnetic material constituting the concentrator components. Therefore, the type of magnetic material constituting the concentrator components must be selected depending on the melting temperature of the substrate plate. Therefore, the first manufacturing method allows for greater freedom in selecting the components of the substrate 30 and the magnetic material concentrator 42.

[0031] According to the cell excitation device 10 of the present embodiment configured as described above, the magnetic material concentrator 42 has magnetic anisotropy, and the magnetic field generating source 22 is disposed on an extension of the easy axis of magnetization of the magnetic material concentrator 42, forming a magnetic circuit in which a magnetic signal generated by the magnetic material concentrator 42 is output to the second surface 34 of the substrate 30 via the magnetic material concentrator 42. Therefore, the magnetic signal generated by the magnetic material concentrator 22 is efficiently input to and converged by the magnetic material concentrator 42, and output to the cell 50 disposed on an extension of the easy axis of the magnetic material concentrator 42. As a result, the magnetic signal that should be generated by the magnetic material concentrator 22 can be suppressed, and the configuration of the magnetic material concentrator 42 and the AC current supply unit 24 attached to the magnetic material concentrator 42 can be simplified and made smaller. Furthermore, because the magnetic field generating unit 12, which is composed of the magnetic field generating source 22 and the magnetic concentrator 42, is arranged two-dimensionally, stimulation with higher spatial resolution can be achieved by appropriately setting the size of the magnetic concentrators 42 arranged in the substrate 30 and the distance between adjacent magnetic concentrators 42 according to the cells 50 to be stimulated. As described above, by realizing high spatial resolution while suppressing the magnetic signal generated by the magnetic field generating source 22, it becomes possible to apply magnetic field stimulation to each individual cell 50 cultured on the second surface 34 of the substrate 30, for example.

[0032] 7 and 8 are explanatory diagrams showing the results of a simulation comparing the behavior of magnetic signals between a configuration including a magnetic material concentrator 42 with magnetic anisotropy, such as the cell excitation device 10 of this embodiment, and a configuration without the magnetic material concentrator 42. FIG. 7 shows the results of investigating the behavior of magnetic signals for a configuration including a magnetic material concentrator 42 with magnetic anisotropy, and FIG. 8 shows the results of investigating the behavior of magnetic signals for a configuration without the magnetic material concentrator 42. FIGS. 7(A) and 8(B) show gray color maps of magnetic signal strength. FIGS. 7(B) and 8(B) show the magnetic flux density distribution on the second surface 34 of the substrate 30, illustrating the magnetic signal attenuation suppression effect. In FIGS. 7(B) and 8(B), the horizontal axis represents the distance in the planar direction on the second surface 34 of the substrate 30, where the midpoint between the two magnetic field generating sources 22 shown in FIGS. 7(A) and 8(A) and the point where the midpoint overlaps with the point in the Z-axis direction are set to 0, and the vertical axis represents magnetic flux density (T). The above simulation was performed using COMSOL Multiphysics, a general-purpose physical simulation software.

[0033] The simulation results shown in FIG. 7 were obtained using a magnetic field source 22 that generated a magnetic field of 5 mT and was placed below a glass substrate 30. A cylindrical magnetic concentrator 42 (height: 300 μm, diameter: 100 μm) made of permalloy (NiFe alloy) was embedded in the glass substrate 30, and the magnetic signal attenuation suppression effect of this flux concentrator structure was simulated. FIG. 8 shows the results of a simulation performed under the same conditions as FIG. 7 except that the magnetic concentrator 42 was not provided. The results shown in FIGS. 7 and 8 indicate that providing the magnetic concentrator 42 of this embodiment increases the magnetic flux density in the area directly above the magnetic concentrator 42 (coordinates −0.2 mm and +0.2 mm) by more than 30 times compared to when the magnetic concentrator 42 is not provided.

[0034] In the cell excitation device 10 of the first embodiment, the magnetic material concentrator 42 is arranged so that the direction perpendicular to the surface direction of the substrate 30 (the Z-axis direction) is the easy axis, and the magnetic field generation source 22 is positioned on an extension of the easy axis of the magnetic material concentrator 42, i.e., so that the magnetic material concentrator 42 and the magnetic field generation source 22 overlap in the Z-axis direction. However, the arrangement of the magnetic material concentrator 42 and the magnetic field generation source 22 may be different from the above. For example, the magnetic material concentrator 42 may be arranged within the substrate 30 so that the easy axis of the magnetic material concentrator 42 is oblique to the surface direction of the substrate 30, and the magnetic field generation source 22 may be positioned on an extension of the easy axis of the magnetic material concentrator 42. Even with such a configuration, it is possible to obtain the same effect as the first embodiment, that is, to achieve high spatial resolution while suppressing the magnetic signal generated by the magnetic field generation source 22.

[0035] B. Second embodiment: In the first embodiment, a cylindrical magnetic material concentrator having at least shape magnetic anisotropy is used as the magnetic material concentrator 42, but a different shape may be used. In the following, as a second embodiment, another example of the magnetic material concentrator 42 having at least shape magnetic anisotropy will be described.

[0036] 9 to 11 are explanatory diagrams showing the configuration of a substrate having an array structure formed by magnetic concentrators having a shape different from that of the first embodiment. FIGS. 9(A), 10(A), and 11(A) are cross-sectional views, while FIGS. 9(B), 10(B), and 11(B) are perspective views. In FIGS. 9(B), 10(B), and 11(B), the position of the cross section of the corresponding FIG. 9(A), 10(A), or 11(A) is shown as an AA cross section. Each of the substrates 130, 230, and 330 shown in FIGS. 9 to 11 can be used in place of the substrate 30 of the first embodiment shown in FIG. 1, and can have the same configuration as the first embodiment except for the shapes of the magnetic concentrators 142, 242, and 342 provided in the substrates 130, 230, and 330.

[0037] FIG. 9 shows each magnetic material concentrator 142 in a conical shape, FIG. 10 shows each magnetic material concentrator 242 in a capsule shape with an elliptical cross section parallel to the central axis, and FIG. 11 shows each magnetic material concentrator 342 in a rectangular parallelepiped shape. In all of FIGS. 9 to 11, each magnetic material concentrator is arranged so that the Z-axis direction (thickness direction of the substrate 30) is the easy axis direction, and in the cell excitation device, the magnetic field generating source 22 is arranged below each magnetic material concentrator on an extension of the easy axis of the magnetic material concentrator. Even with this configuration, the same effects as those of the first embodiment can be obtained. Note that, as the magnetic material concentrator having shape magnetic anisotropy with the Z-axis direction as the easy axis direction, other shapes, such as a pyramidal shape with a polygonal base, may be used.

[0038] C. Third embodiment: FIG. 12 is an explanatory diagram showing the configuration of a magnetic material concentrator 442 according to a third embodiment. Note that FIG. 12 shows a portion of the magnetic material concentrator 442 in a cutaway view. The magnetic material concentrator 442 according to the third embodiment can be used in place of the magnetic material concentrator 42 in the cell excitation device 10 according to the first embodiment. Like the magnetic material concentrator 42, the magnetic material concentrator 442 has a cylindrical shape, with the longitudinal direction of the cylindrical shape being the formal easy axis direction of the magnetic material concentrator. However, the magnetic material concentrator 442 differs from the magnetic material concentrator 42 in that a portion including its surface (side surface) has a closed-circuit magnetic domain structure in a direction perpendicular to the easy axis direction. That is, the magnetic material concentrator 442 has a closed-circuit magnetic domain structure in the circumferential direction in a portion including the surface (side surface) of the cylindrical shape. In FIG. 12, the direction of the local easy axis in the outer periphery, including the side surface, of the cylindrical magnetic material concentrator 442 is indicated by an arrow. 12, in the cylindrical magnetic material concentrator 442, an easy axis is formed in the circumferential direction (perpendicular to the longitudinal direction of the cylindrical shape) along the outer periphery at the outer periphery including the side surfaces, and this prevents magnetic flux from penetrating into the magnetic material concentrator 442 from directions other than the easy axis (the longitudinal direction of the cylindrical shape). Such a closed-circuit magnetic domain structure can be formed, for example, by performing tension heat treatment or Joule annealing on the cylindrical member that will become the magnetic material concentrator 442.

[0039] FIG. 13 is an explanatory diagram showing the magnetization curve of the magnetic material concentrator 442. FIG. 13(A) shows the magnetization curve in the longitudinal direction of the cylindrical shape, and FIG. 13(B) shows the magnetization curve in the circumferential direction. The magnetic material concentrator 442 has a closed-circumferential magnetic domain structure, which generates a ferromagnetic hysteresis curve as shown in FIG. 13(B). As shown in FIG. 13(B), this generates a large coercive force and reduces the magnetic permeability near zero magnetic field. Therefore, in the magnetic material concentrator 442, magnetic flux is less likely to enter from the side, and the direction of magnetic flux convergence, i.e., the direction of magnetic flux for stimulating cells 50, can be limited to the easy axis direction (the longitudinal direction of the cylindrical shape). Therefore, a cell excitation device having such an array structure of magnetic material concentrators 442 can further improve the spatial resolution for exciting cells 50.

[0040] D. Fourth embodiment: Fig. 14 is an explanatory diagram showing the schematic configuration of a cell excitation device 510 of the fourth embodiment in the same manner as Fig. 1. In the cell excitation device 510, parts common to the cell excitation device 10 of the first embodiment are given the same reference numerals.

[0041] In the cell excitation device, a magnetic field source or a part of the magnetic field source can be used as a magnetic concentrator, and the magnetic field source and the magnetic concentrator can be integrated. As an example, FIG. 14 shows a magnetic field source that generates an AC magnetic field using part of the components constituting the magnetic concentrator. Specifically, the cell excitation device 510 includes, instead of the magnetic concentrator 42, a magnetic concentrator 542, which is a magnetic wire having magnetic anisotropy with the easy axis in the Z-axis direction. The magnetic concentrator 542 extends further in the -Z-axis direction from the first surface 32 of the substrate 30. This portion extending in the -Z-axis direction is combined with a coil to form the magnetic field source 522.

[0042] With this configuration, in addition to the same effects as the cell excitation device 10 of the first embodiment, the connection structure between the magnetic material concentrator and the magnetic field generation source is not required, thereby simplifying the overall configuration of the cell excitation device. Furthermore, since there is no magnetic circuit gap between the magnetic material concentrator and the magnetic field generation source, attenuation of the magnetic signal generated by the magnetic field generation source can be suppressed, thereby improving the efficiency of stimulating the cells 50. In the cell excitation device 510 shown in FIG. 14, the magnetic material concentrator 542 may further have a closed-circuit magnetic domain structure as described in the third embodiment.

[0043] E. Fifth embodiment: Fig. 15 is an explanatory diagram showing the schematic configuration of a cell excitation device 610 of the fifth embodiment in the same manner as Fig. 1, and Fig. 16 is a perspective view showing part of the appearance of the cell excitation device 610 in the same manner as Fig. 2. In the cell excitation device 610, parts common to the cell excitation device 10 of the first embodiment are given the same reference numerals.

[0044] In the cell excitation device 10 of the first embodiment, a pair of magnetic concentrators 42 and a magnetic field source 22 constitute a magnetic field generating unit 12, and within the magnetic field generating unit 12, the magnetic field generating source 22 is arranged on an extension of the easy axis of magnetization of the single magnetic field concentrator 42 corresponding to the magnetic field generating source 22. However, a different configuration may be used. In the cell excitation device, the magnetic field generating source and the magnetic field concentrator corresponding to the magnetic field generating source are only required to be arranged so as to form a magnetic circuit in which a magnetic signal generated by the magnetic field generating source is output to the second surface of the substrate via the magnetic field concentrator. In the cell excitation device 610 shown in FIGS. 15 and 16, a pair of magnetic field concentrators 642 arranged adjacent to each other within the substrate 30 and a magnetic field generating source 622 arranged magnetically connected to both of the pair of magnetic field concentrators 642 on the first surface 32 of the substrate 30 constitute a magnetic field generating unit 612, and multiple magnetic field generating units 612 are arranged in an array.

[0045] As shown in Figures 15 and 16, each of the pair of magnetic concentrators 642 constituting the magnetic field generating unit 612 has shape magnetic anisotropy and is formed in a quadrangular pyramidal truncated shape. Also, Figures 15 and 16 show how a magnetic field generating source 622 that generates an AC magnetic field with a coil wound around a magnetic core is arranged horizontally (parallel to the XY plane) and magnetically connected to each of the pair of magnetic concentrators 642. In the cell excitation device 610 of the fifth embodiment, as described above, two magnetic concentrators 642 are provided for each of the magnetic field generating sources 22.

[0046] In such a cell excitation device 610, when a cell 50 is placed between a pair of magnetic concentrators 642 on the second surface 34 of the substrate 30, magnetic flux from the magnetic field generating source 622 flows into one of the magnetic concentrators 642, where it is converged, and then flows out toward the cell 50. This flow of magnetic flux then flows from the cell 50 into the other magnetic concentrator 642, where it is converged. In this way, the magnetic circuit formed by the magnetic field generating unit 612, including the cell 50, has two flows, a clockwise flow and a counterclockwise flow, as shown in FIG. 15 , and the flow direction of the magnetic flux is converted from a lateral direction to a direction toward the cell 50 by passing through the magnetic concentrator 642 within the magnetic circuit.

[0047] 17 and 18 are explanatory diagrams showing the results of a simulation comparing the behavior of magnetic signals between a configuration including a pair of magnetic material concentrators 642 with magnetic anisotropy, such as the cell excitation device 610 of the fifth embodiment, and a configuration without such a configuration. FIG. 17 shows the results of investigating the behavior of magnetic signals for a configuration including magnetic material concentrators 642 with magnetic anisotropy, and FIG. 18 shows the results of investigating the behavior of magnetic signals for a configuration without magnetic material concentrators 642. FIGS. 17(A) and 18(A) show gray color maps of magnetic signal strength. FIGS. 17(B) and 18(B) show the magnetic flux density distribution in the longitudinal direction of the magnetic field generator 622 on the second surface 34 of the substrate 30 (the X-axis direction in FIG. 15, where the longitudinal length of the magnetic field generator 622 is 0.1 mm), showing the magnetic signal attenuation suppression effect. 17(B) and 18(B), the horizontal axis represents the distance from the position where the center of the magnetic field generating source 622 in the longitudinal direction on the second surface 34 of the substrate 30 overlaps with the Z-axis direction, and the vertical axis represents the magnetic flux density (T). The above simulation was performed using COMSOL Multiphysics, which is general-purpose physical simulation software.

[0048] The simulation results shown in FIG. 17 were obtained using a magnetic field generating source 622 that generates a magnetic field of 5 mT and is disposed below a glass substrate 30. A truncated-pyramid magnetic concentrator 642 made of permalloy (NiFe alloy) was embedded in the glass substrate 30, and the magnetic signal attenuation suppression effect of this flux concentrator structure was simulated. The magnetic concentrator 642 had dimensions of 0.2 mm in width, 0.3 mm in height, and 0.02 mm in depth. FIG. 18 shows the results of a simulation performed under the same conditions as FIG. 17 except that the magnetic concentrator 642 was not provided. The results shown in FIGS. 17 and 18 indicate that by adopting the structure of the magnetic field generating unit 612 of this embodiment, the magnetic flux density in the area directly above the magnetic concentrator 642 is increased by more than 30 times compared to when the magnetic concentrator 642 is not provided.

[0049] F. Sixth embodiment: Figure 19 is an explanatory diagram showing the schematic configuration of a cell excitation device 710 of the sixth embodiment in the same manner as Figure 1. In the cell excitation device 710, parts common to the cell excitation device 10 of the first embodiment are given the same reference numerals.

[0050] 1, the cell excitation device 710 of the sixth embodiment includes a substrate 30 on which a plurality of magnetic material concentrators 42 are arranged two-dimensionally. In the cell excitation device 710, some of the plurality of magnetic material concentrators 42 arranged on the substrate 30 constitute a magnetic field generating unit 12 together with a corresponding magnetic field generating source 22. The magnetic field generating sources 22 included in the cell excitation device 710 are arranged two-dimensionally to form a magnetic field generating source array 20, and each of the magnetic field generating sources 22 receives an alternating current from an alternating current supply unit 24 to generate a magnetic field.

[0051] Furthermore, in the cell excitation device 710, among the multiple magnetic material concentrators 42 provided on the substrate 30, each of the remaining magnetic material concentrators 42, which are different from the aforementioned partial magnetic material concentrators 42, constitutes a sensor unit 14 together with a corresponding magnetic sensor element 72. The magnetic sensor element 72 can be configured in the same manner as the magnetic field generating source 22, i.e., by a coil or a coil and a magnetic material core. In FIG. 19, the magnetic sensor element 72 is represented as a magnetic impedance element in which a pickup coil is wound around a magnetic wire. The magnetic sensor elements 72 provided in the cell excitation device 710 are arranged two-dimensionally in the XY plane to form a magnetic sensor array 70, and each magnetic sensor element 72 is connected to a detection unit 74. The detection unit 74 individually acquires a detection signal from each magnetic sensor element 72 to which a magnetic signal is input.

[0052] In each sensor unit 14, when a cell 50 serving as a signal source is present on the magnetic concentrator 42 on the second surface 34 of the substrate 30, the magnetic flux emitted from the cell 50 is converged by the magnetic concentrator 42 to suppress attenuation and applied to the magnetic sensor element 72. This increases the detection sensitivity when detecting a magnetic signal from the cell 50 using the magnetic sensor element 72. At this time, the direction of the magnetic flux converged by the magnetic concentrator 42 is limited to one direction corresponding to the easy axis of the magnetic concentrator 42, and each magnetic concentrator 42 mainly converges the magnetic flux from a specific cell 50 serving as a signal source arranged on the magnetic concentrator 42, allowing the corresponding magnetic sensor element 72 to detect the magnetic flux from the specific cell 50 with high sensitivity. Furthermore, since the sensor unit 14, which is composed of the magnetic sensor element 72 and the magnetic concentrator 42, is arranged two-dimensionally, measurements with higher spatial resolution can be performed by appropriately setting the size of the magnetic concentrators 42 arranged in the substrate 30 and the distance between adjacent magnetic concentrators 42 according to the cells 50 to be detected. By achieving high spatial resolution while increasing the detection sensitivity as described above, it becomes possible to distinguish and detect weak signals, such as magnetic signals from individual cardiomyocytes or nerve cells, for each cell.

[0053] As described above, in the cell excitation device 710 of the sixth embodiment, the magnetic field generation source 22 and the magnetic sensor element 72 are formed from the same material, and the magnetic field generation unit 12 and the sensor unit 14 have a common structure. Therefore, instead of using the structure functioning as the magnetic field generation unit 12 or the sensor unit 14 for only one purpose, the structure may be made switchable between being connected to the AC current supply unit 24 or the detection unit 74, so that it can be used for either the magnetic field generation unit 12 or the sensor unit 14. With this configuration, both cell excitation and detection of magnetic signals from cells can be performed with high spatial resolution in a wide area where the structure functioning as the magnetic field generation unit 12 or the sensor unit 14 is provided.

[0054] G. Seventh embodiment: Figure 20 is an explanatory diagram showing the schematic configuration of a cell excitation device 810 of the seventh embodiment in the same manner as Figure 1. In the cell excitation device 810, parts common to the cell excitation device 10 of the first embodiment are given the same reference numerals.

[0055] The cell excitation device 810 of the seventh embodiment includes a substrate 30 on which a plurality of two-dimensionally arranged magnetic material concentrators 42 are provided, similar to the cell excitation device 10 shown in FIG. 1 . However, in the cell excitation device 810, a magnetic field generation source 22 is not provided for each magnetic material concentrator 42, but one magnetic field generation source 22 is provided for each of the plurality of magnetic material concentrators 42. The cell excitation device 810 also includes a movement mechanism 880 that two-dimensionally moves at least one of the magnetic field generation source 22 and the substrate 30 horizontally so that the magnetic field generation source 22 is positioned on an extension of the magnetization easy axis of each of the plurality of magnetic material concentrators 42. That is, the movement mechanism 880 may horizontally move a stage supporting the substrate 30 in the XY plane while the magnetic field generation source 22 is fixed, or may horizontally move the magnetic field generation source 22 while the substrate 30 is fixed, or may horizontally move both the magnetic field generation source 22 and the substrate 30 in the XY plane. With this configuration, it is possible to reduce the number of magnetic field generating sources 22 provided in the cell excitation device 810, while applying magnetic field stimulation to the cell 50 via the magnetic concentrator 42 located close to the cell 50 to be stimulated.

[0056] H. Eighth embodiment: Fig. 21 is an explanatory diagram showing the schematic configuration of a cell excitation device 910 of the eighth embodiment in the same manner as Fig. 1. However, Fig. 21 shows an enlarged view of a specific magnetic field generating unit 12. In the cell excitation device 910, parts common to the cell excitation device 10 of the first embodiment are given the same reference numerals.

[0057] The cell excitation device 910 of the eighth embodiment has a structure similar to that of the cell excitation device 10 shown in FIG. 1, and further includes a magnetoelectric element 982 that converts magnetic signals into electric signals, disposed on the second surface 34 of the substrate 30. The magnetoelectric element 982 is formed of a material in which electric polarization is induced when a magnetic field is applied, and may be formed of, for example, antiferromagnetic materials such as α-TiO and α-CrO, or ferrimagnetic materials such as GaFeO. The magnetoelectric element 982 may be disposed near the cell 50, and it is desirable that at least one of the cell 50 and the magnetoelectric element 982 be disposed on an extension of the easy axis of magnetization of the magnetic material concentrator 42. In other words, the cell 50 may be disposed on an extension of the easy axis of magnetization of the magnetic material concentrator 42, and the magnetoelectric element 982 may be disposed near the cell 50. Alternatively, the magnetoelectric element 982 may be disposed on an extension of the easy axis of magnetization of the magnetic material concentrator 42, and the cells 50 may be present near the magnetoelectric element 982. The magnetoelectric element 982 may or may not be in contact with the magnetic material concentrator 42. Even if the magnetoelectric element 982 and the magnetic material concentrator 42 are spaced apart, the distance between them is preferably within 5 mm. The magnetoelectric element 982 does not need to be fixed on the second surface 34 of the substrate 30. For example, the magnetoelectric element 982 may be further dispersed in a culture medium after the cells 50 are seeded on the second surface 34 of the substrate 30. Alternatively, a gel layer that holds the magnetoelectric element 982 may be provided on the second surface 34 of the substrate 30, and the cells 50 may be seeded and cultured on this gel layer. From the viewpoint of applying a stimulus to each cell 50, the particle diameter of the magnetoelectric element 982 may be approximately the same as the diameter of the cylindrical magnetic material concentrator 42, and is preferably, for example, 1 mm or less, and more preferably, 100 μm or less. With this configuration, the magnetic signal from the magnetic field generating source 22, which is converged by the magnetic material concentrator 42, is converted into an electric signal in the magnetoelectric element 982, and an electric stimulus is applied to the cell 50 present in the vicinity of the magnetoelectric element 982. Such an electric stimulus can be, for example, a stimulus for inducing a membrane potential change related to the opening and closing of a channel in the cell membrane.

[0058] In the cell excitation device 910 of the eighth embodiment, the magnetoelectric element 982 is disposed in advance on the second surface 34 of the substrate 30, but a different configuration may be used. For example, a method may be used in which an antibody to a surface protein (membrane protein) of the cell 50 is immobilized on the magnetoelectric element 982, and particles of the magnetoelectric element 982 are attached to the cell 50 by utilizing an antigen-antibody reaction.

[0059] I. Ninth embodiment: Fig. 22 is an explanatory diagram showing the schematic configuration of a cell excitation device 1010 of the ninth embodiment. Fig. 22(A) is a perspective view, and Fig. 22(B) is a cross-sectional view. In the cell excitation device 1010, parts common to the cell excitation device 10 of the first embodiment are given the same reference numerals. Note that in Fig. 22, the internal structure of the magnetic field generation source array 20 is omitted.

[0060] In addition to the same configuration as the cell excitation device 10, the cell excitation device 1010 further includes a shield portion 1060 provided on the second surface 34 of the substrate 30, protruding from the second surface 34 and surrounding the entire area where the multiple magnetic concentrators 42 are arranged. FIG. 22 shows a cylindrical shield portion 1060 provided along the outer periphery of the substrate 30. The shield portion 1060 is a structure for blocking magnetic flux and may be made of a material that prevents the passage of magnetic flux, such as a ferromagnetic material (high-permeability magnetic material) that absorbs magnetic force. With this configuration, each magnetic field generating unit 12 can block environmental noise from around the cell excitation device 1010 and accurately apply the desired magnetic stimulation to the cells to be stimulated that are arranged on the second surface 34 of the substrate 30.

[0061] J. Tenth embodiment: Figure 23 is an explanatory diagram showing the schematic configuration of a cell excitation device 1110 of the tenth embodiment. Figure 23(A) is a top view of one magnetic field generating unit 12, Figure 23(B) is a perspective view of the cell excitation device 1110, and Figure 23(C) is a cross-sectional view of the cell excitation device 1110. In the cell excitation device 1110, parts common to the cell excitation device 10 of the first embodiment are given the same reference numerals. Note that in Figure 23, the internal structure of the magnetic field generation source array 20 is omitted.

[0062] In addition to the same configuration as the cell excitation device 10, the cell excitation device 1110 further includes a shield portion 1160 provided on the second surface 34 of the substrate 30, protruding from the second surface 34 and surrounding the area where each magnetic concentrator 42 is arranged. FIG. 23 shows a cylindrical shield portion 1160 provided to surround each magnetic concentrator 42. The shield portion 1160 is a structure for blocking magnetic flux and may be made of a material that prevents the passage of magnetic flux, such as a ferromagnetic material (high-permeability magnetic material) that absorbs magnetic force. This configuration improves the reliability of blocking environmental noise from around the cell excitation device in each magnetic field generating unit 12, further improving the accuracy of applying the desired magnetic stimulation to the cells to be stimulated.

[0063] K. Other Embodiments: In the above-described embodiments, when applying a magnetic field stimulus to cells using the cell excitation device, the cells to be stimulated are cultured on the second surface 34 of the substrate 30. However, other configurations are also possible. For example, when cultured cells prepared separately from the cell excitation device are used as the stimulation target, the cell excitation device can be inverted and the second surface 34 of the substrate 30 can be brought close to or in contact with the cells prepared separately from the cell excitation device, thereby stimulating the cells. Furthermore, the stimulation target may be, in addition to cultured cells, for example, biological tissue composed of cells or a living organism having such biological tissue. [Example]

[0064] A substrate 30 including a magnetic concentrator 42 in the cell excitation device 10 described in the first embodiment was fabricated, and it was confirmed that it could be suitably used in applications in which cells cultured on the second surface 34 of the substrate 30 were used as stimulation targets. Here, the manufacturing method shown in FIG. 4 was followed. A cylindrical member (diameter 0.6 mm) made of permalloy (NiFe alloy) was used as the concentrator member prepared in step T100. A glass plate (thickness 1 mm) was used as the substrate plate prepared in step T120. A silica-based adhesive was used as the adhesive used in step T150.

[0065] Figure 24 is an explanatory diagram showing a photograph of the fabricated cell excitation device 10. Figure 24(A) shows a photograph of the cell excitation device 10 viewed from above, and Figure 24(B) is a photograph of a perspective view of the cell excitation device 10. As shown in Figure 24, a plurality of magnetic concentrators 42 were provided in an array within a highly transparent glass substrate 30, penetrating the substrate 30 so that their ends were exposed on the second surface 34 of the substrate 30.

[0066] 25 and 26 are explanatory diagrams showing the results of a non-contact measurement of the surface roughness of the second surface 34 of the substrate 30 using a 3D measuring laser microscope after the polishing process (mechanical polishing) in step T160. FIG. 25(A) shows the surface height display (2D), and FIG. 25(B) shows the surface height display (3D). Height profiles were also acquired along two orthogonal lines shown as "Line 1" and "Line 2" in FIG. 24(A). That is, height profiles were acquired continuously along "Line 1" and "Line 2" on the second surface 34, from outside the outer periphery of the magnetic concentrator 42, across the edge of the magnetic concentrator 42 so as to pass through the center of the magnetic concentrator 42, and beyond the outer periphery of the magnetic concentrator 42. FIG. 26(A) shows the height profile along "Line 1," and FIG. 26(B) shows the height profile along "Line 2." 26(A) and 26(B), the horizontal axis indicates the distance from the starting point of the profile acquisition for each line, and the vertical axis indicates the height profile. As shown in FIGS. 25 and 26, the difference in height between the highest and lowest points on the second surface 34 was 10 μm or less, specifically 4 μm or less.

[0067] After polishing in step T160, a coating layer made of a cell adhesion coating agent was formed on the second surface 34 of the substrate 30, covering the area including the region where the plurality of magnetic concentrators 42 were formed. Specifically, the coating layer was formed so as to cover the entire second surface 34 of the substrate 30, inside which the plurality of magnetic concentrators 42 were formed. Two types of cell adhesion coating agents were used: collagen and Matrigel. Specifically, the substrate 30 was placed in a 6-well plate, 2 mL of phosphate buffered saline was added, and 20 μL of Cellmatrix type IA (Nitta Gelatin Co., Ltd.), which contains collagen, or typically 20 μL of Matrigel (Corning Incorporated; Matrigel is a registered trademark) (variable depending on the lot) was added. The plate was stirred and then allowed to stand in a CO2 incubator for 1 hour, thereby carrying out the coating process. After the above coating process, the liquid containing the cell adhesive coating agent was removed by suction from the substrate 30, and then cells were seeded and cultured on each substrate 30 on which the coating layer had been formed. First, to disinfect bacteria present on the surface of the substrate 30, the substrate was placed in a well of a 12-well multiwell plate and treated with 70% ethanol for 15 minutes. Then, the ethanol was removed, and the surface of the substrate 30 was rinsed with sterilized water to completely remove the cleaning solution, and then air-dried. HEK293 cells were used for seeding the cells at a density of 1.5 x 104 cells / cm. 2 The cells were seeded at a density of 1000 x g in a suspension in a medium (RPMI1640-10% FBS).

[0068] Figure 27 is an explanatory diagram showing the results of fluorescent observation of cells after culture. Figure 27 shows the results of a substrate 30 with magnetic concentrators 42 formed thereon, using collagen or Matrigel as a cell adhesion coating agent, as well as the results of similar cell seeding and culture using a slide glass coated with collagen or Matrigel as a comparative example. Figure 27 shows a bright-field image, fluorescently stained images of live cells, and fluorescently stained images of dead cells. In the image of the substrate 30 with magnetic concentrators 42 formed thereon, the area where the magnetic concentrators 42 are formed is indicated by a dashed line. As shown in Figure 27, cells adhered and proliferated on the substrate 30 with magnetic concentrators 42 as well as on a slide glass, and the coated surface was efficiently covered by cells. Furthermore, like a slide glass, the substrate 30 with magnetic concentrators 42 formed thereon exhibited no cytotoxicity, confirming its suitability for use in applications where cells cultured on the substrate 30 are used as a stimulation target.

[0069] The present disclosure is not limited to the above-described embodiments, and can be realized in various configurations without departing from the spirit thereof. For example, the technical features in the embodiments corresponding to the technical features in each aspect described in the Summary of the Invention section can be appropriately replaced or combined to solve some or all of the above-described problems or achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted.

[0070] The present disclosure can also be realized in the following forms. [Application example 1] 1. A cell excitation device, comprising: a magnetic field source that generates a magnetic field; a substrate disposed on the magnetic field generating source, the substrate having a second surface different from a first surface facing the magnetic field generating source, the second surface being a surface for arranging cells on the surface or a surface for arranging cells facing the surface; a magnetic concentrator array configured by a plurality of magnetic concentrators arranged two-dimensionally within the substrate; Equipped with each of the plurality of magnetic concentrators has magnetic anisotropy; In a state where the magnetic field generating source is disposed on an extension line of the easy axis of magnetization of the magnetic material concentrator, a magnetic circuit is formed in which a magnetic signal generated by the magnetic field generating source is output to the second surface via the magnetic material concentrator. Cell excitation device. [Application example 2] The cell excitation device according to Application Example 1, further comprising: a current supply unit that supplies a current for generating a magnetic field to the magnetic field generation source, The magnetic field source is composed of a coil or a coil and a magnetic core. Cell excitation device. [Application example 3] The cell excitation device according to Application Example 1 or 2, a plurality of said magnetic field generating sources; the plurality of magnetic field generating sources have a two-dimensionally arranged array structure; each of the magnetic field generating sources constitutes a magnetic field generating unit together with the corresponding magnetic material concentrator; In each of the magnetic field generating units, the magnetic field generating source is disposed on an extension of the magnetic easy axis of the corresponding magnetic material concentrator. Cell excitation device. [Application example 4] The cell excitation device according to Application Example 3, each of the plurality of magnetic concentrators is arranged such that the direction perpendicular to the surface direction of the substrate is the axis of easy magnetization; Each of the magnetic field generating sources is disposed at a position overlapping the corresponding magnetic concentrator in a direction perpendicular to the surface direction of the substrate. Cell excitation device. [Application example 5] The cell excitation device according to Application Example 1 or 2, further comprising: a moving mechanism for two-dimensionally moving at least one of the magnetic field generating source and the substrate horizontally so that the magnetic field generating source is positioned on an extension line of the magnetic easy axis of each of the plurality of magnetic concentrators; Cell excitation device. [Application Example 6] The cell excitation device according to any one of Application Examples 1 to 5, Each of the plurality of magnetic concentrators is disposed embedded in the substrate or disposed through the substrate. Cell excitation device. [Application Example 7] The cell excitation device according to any one of Application Examples 1 to 6, Each of the plurality of magnetic concentrators is made of a soft magnetic material having one or more of shape magnetic anisotropy, induced magnetic anisotropy, stress magnetic anisotropy, and magnetocrystalline anisotropy. Cell excitation device. [Application Example 8] The cell excitation device according to Application Example 7, Each of the plurality of magnetic concentrators has shape magnetic anisotropy and is formed in a shape selected from a cylindrical shape, a rectangular parallelepiped shape, a capsule shape in which the cross section parallel to the central axis is an ellipse, a pyramidal shape, and a conical shape. Cell excitation device. [Application Example 9] The cell excitation device according to any one of Application Examples 1 to 8, Each of the plurality of magnetic concentrators has magnetic anisotropy, and has a closed-circuit magnetic domain structure in an outer periphery including a surface of the magnetic concentrator that suppresses the penetration of magnetic flux from directions other than the easy magnetization direction related to the magnetic anisotropy. Cell excitation device. [Application Example 10] The cell excitation device according to any one of Application Examples 1 to 9, The magnetic concentrator and at least a part of the magnetic field generating source provided corresponding to the magnetic concentrator are integrally formed. Cell excitation device. [Application Example 11] The cell excitation device according to any one of Application Examples 1 to 10, a coating layer including a cell adhesive component is provided on the second surface of the substrate so as to cover an area including an area where the plurality of magnetic concentrators are formed; The diameter of a cross section of each of the plurality of magnetic concentrators parallel to the surface direction of the substrate is 5 μm or more and 1000 μm or less. Cell excitation device. [Application Example 12] The cell excitation device according to any one of Application Examples 1 to 11, the magnetic concentrator is exposed on the second surface of the substrate; The difference in height between the second surface of the substrate and the portion of the magnetic concentrator exposed at the second surface is 10 μm or less. Cell excitation device. [Application Example 13] The cell excitation device according to any one of Application Examples 1 to 12, further comprising: a shield portion that protrudes from the second surface of the substrate and is provided so as to surround the entire area in which the plurality of magnetic concentrators are arranged, and that prevents passage of magnetic flux; Cell excitation device. [Application Example 14] The cell excitation device according to any one of Application Examples 1 to 12, further comprising: a shield portion provided on the second surface of the substrate, protruding from the second surface, surrounding an area where the magnetic concentrator is disposed for each magnetic concentrator, and preventing passage of magnetic flux; Cell excitation device. [Application Example 15] The cell excitation device according to any one of Application Examples 1 to 14, a magnetic sensor element is disposed on the first surface side of the substrate in place of the magnetic field generation source in correspondence with some of the plurality of magnetic concentrators; The magnetic sensor element and a magnetic concentrator provided corresponding to the magnetic sensor element are arranged to form a magnetic circuit in which a magnetic signal is input to the magnetic sensor element via the magnetic concentrator. Cell excitation device. [Application Example 16] The cell excitation device according to any one of Application Examples 1 to 15, further comprising: a magnetoelectric element on the second surface of the substrate that converts a magnetic signal into an electric signal; On the second surface of the substrate, at least one of the cells and the magnetoelectric element is arranged on an extension of the easy axis of magnetization of the magnetic concentrator. Cell excitation device. [Explanation of symbols]

[0071] 10,510,610,710,810,910,1010,1110...Cell excitation device 12,612...magnetic field generating unit 14...Sensor unit 20...Magnetic field source array 22,522,622...magnetic field source 24...AC current supply section 30, 130, 230, 330... PCB 32...First side 34...Second side 35...Adhesive 40...Magnetic concentrator array 42, 142, 242, 342, 442, 542, 642...Magnetic concentrators 50...cell 70...Magnetic sensor array 72...Magnetic sensor element 74...Detection unit 880…Movement mechanism 982...Magnetoelectric elements 1060, 1160...Shield part

Claims

1. 1. A cell excitation device, comprising: a magnetic field source that generates a magnetic field; a substrate disposed on the magnetic field generating source, the substrate having a second surface different from a first surface facing the magnetic field generating source, the second surface being a surface for arranging cells on the surface or a surface for arranging cells facing the surface; a magnetic concentrator array configured by a plurality of magnetic concentrators arranged two-dimensionally within the substrate; Equipped with each of the plurality of magnetic concentrators has magnetic anisotropy; In a state where the magnetic field generating source is disposed on an extension line of the easy axis of magnetization of the magnetic material concentrator, a magnetic signal generated by the magnetic field generating source is output to the second surface via the magnetic material concentrator, forming a magnetic circuit. Cell excitation device.

2. The cell excitation device according to claim 1, further comprising: a current supply unit that supplies a current for generating a magnetic field to the magnetic field generation source, The magnetic field source is composed of a coil or a coil and a magnetic core. Cell excitation device.

3. 2. The cell excitation device according to claim 1, a plurality of said magnetic field generating sources; the plurality of magnetic field generating sources have a two-dimensionally arranged array structure, each of the magnetic field generating sources constitutes a magnetic field generating unit together with the corresponding magnetic material concentrator; In each of the magnetic field generating units, the magnetic field generating source is disposed on an extension of the magnetic easy axis of the corresponding magnetic material concentrator. Cell excitation device.

4. 4. The cell excitation device according to claim 3, each of the plurality of magnetic concentrators is arranged such that the direction perpendicular to the surface direction of the substrate is the axis of easy magnetization; Each of the magnetic field generating sources is disposed at a position overlapping the corresponding magnetic concentrator in a direction perpendicular to the surface direction of the substrate. Cell excitation device.

5. The cell excitation device according to claim 1, further comprising: a moving mechanism for two-dimensionally moving at least one of the magnetic field generating source and the substrate horizontally so that the magnetic field generating source is positioned on an extension line of the magnetic easy axis of each of the plurality of magnetic concentrators; Cell excitation device.

6. 2. The cell excitation device according to claim 1, Each of the plurality of magnetic concentrators is disposed embedded in the substrate or disposed through the substrate. Cell excitation device.

7. 2. The cell excitation device according to claim 1, Each of the plurality of magnetic concentrators is made of a soft magnetic material having one or more properties of shape magnetic anisotropy, induced magnetic anisotropy, stress magnetic anisotropy, and magnetocrystalline anisotropy. Cell excitation device.

8. 8. The cell excitation device according to claim 7, Each of the plurality of magnetic concentrators has shape magnetic anisotropy and is formed in a shape selected from a cylindrical shape, a rectangular parallelepiped shape, a capsule shape in which the cross section parallel to the central axis is an ellipse, a pyramidal shape, and a conical shape. Cell excitation device.

9. 2. The cell excitation device according to claim 1, Each of the plurality of magnetic concentrators has magnetic anisotropy, and has a closed-circuit magnetic domain structure in an outer periphery including a surface of the magnetic concentrator that suppresses the penetration of magnetic flux from directions other than the easy magnetization direction related to the magnetic anisotropy. Cell excitation device.

10. 2. The cell excitation device according to claim 1, The magnetic concentrator and at least a part of the magnetic field generating source provided corresponding to the magnetic concentrator are integrally formed. Cell excitation device.

11. 2. The cell excitation device according to claim 1, a coating layer including a cell adhesive component is provided on the second surface of the substrate so as to cover an area including an area where the plurality of magnetic concentrators are formed; The diameter of a cross section of each of the plurality of magnetic concentrators parallel to the surface direction of the substrate is 5 μm or more and 1000 μm or less. Cell excitation device.

12. 12. The cell excitation device according to claim 11, the magnetic concentrator is exposed at the second surface of the substrate; The difference in height between the second surface of the substrate and the portion of the magnetic concentrator exposed at the second surface is 10 μm or less. Cell excitation device.

13. The cell excitation device according to claim 1, further comprising: a shield portion that protrudes from the second surface of the substrate, is provided so as to surround the entire area in which the plurality of magnetic concentrators are arranged, and prevents passage of magnetic flux; Cell excitation device.

14. The cell excitation device according to claim 1, further comprising: a shield portion provided on the second surface of the substrate, protruding from the second surface, surrounding an area where the magnetic concentrator is disposed for each magnetic concentrator, and preventing passage of magnetic flux; Cell excitation device.

15. 2. The cell excitation device according to claim 1, magnetic sensor elements are arranged on the first surface side of the substrate in correspondence with some of the plurality of magnetic concentrators, instead of the magnetic field generation sources; The magnetic sensor element and a magnetic concentrator provided corresponding to the magnetic sensor element are arranged to form a magnetic circuit in which a magnetic signal is input to the magnetic sensor element via the magnetic concentrator. Cell excitation device.

16. The cell excitation device according to claim 1, further comprising: a magnetoelectric element on the second surface of the substrate for converting a magnetic signal into an electric signal; On the second surface of the substrate, at least one of the cells and the magnetoelectric element is arranged on an extension of the easy axis of magnetization of the magnetic concentrator. Cell excitation device.

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