magnetic field generator

Abstract

To provide a magnetic field generator which realizes a magnet field of a variable direction for use in magnetically operating medical objects in the body.SOLUTION: A magnetic field generator comprises at least three magnet groups consisting of permanent magnets 1. The magnetic moment of each magnet is rotatable about a rotation axis. Each group arranged on opposed sides of a workspace 3 comprises at least two magnets. Each group has an orientation such that the rotation axes of the magnetic moments of the magnets included in the group extend in the group's orientation. The orientations of the multiple groups are linearly independent.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a magnetic field generating device. The present invention further relates to a magnetic field generating device. Finally, the present invention relates to the above magnetic field generating device and the above method. Regarding the use of. [Background technology]

[0002] In a three-dimensional working space, a magnetic field with high magnetic flux density and whose direction can be arbitrarily controlled is called the working space. It is desirable to generate it while keeping the space accessible. Three techniques are used to achieve this.

[0003] A magnetic field can be generated by an electromagnetic coil. The strength and direction of the magnetic field can be controlled by moving the coil. It can be easily controlled by the current flowing through it. Typical examples are Helmholtz coils and Maxwell coils. However, electromagnets can have many drawbacks in practice. a) Joule heating causes the temperature of the coil (and therefore its resistance) to rise and This leads to increased temperatures in the surrounding workspace and often requires complex cooling systems. Furthermore, b) the coil structure that realizes a large magnetic field is heavy and requires a large amount of electricity to drive it. amplifiers are expensive, and c) the magnetic field strength is limited, requiring a workspace enclosed by the coil. Increasing or decreasing the magnetic field strength to allow for a larger capacity (e.g., large enough to accommodate a person) It's not easy.

[0004] Another approach is to use superconducting magnetic coils, such as those used in MRI machines. The superconducting magnetic coil can generate a very strong magnetic field (0.2T to 9T). However, it is not easy to change the direction and magnitude of the magnetic field, and it is difficult to achieve a cryogenic temperature. A cooling system is required.

[0005] The third method involves superimposing the magnetic fields generated by each permanent magnet to produce a stronger magnetic field. The purpose of this method is to arrange multiple permanent magnets so that the magnets can be rotated in a direction and at least By mechanically changing either one, the direction of the superimposed magnetic field can be changed. .

[0006] Compared to electromagnetic coils and superconducting coils, permanent magnets do not require any current, so they do not generate heat or On the other hand, changing the magnet direction or position requires mechanical rotation or translation. This requires a high degree of precision, but vibrations can occur and, more seriously, mechanical movement of the magnets. This limits access to the workspace, i.e., the volume enclosed by the magnet. access to medical services may be restricted (or even completely blocked). In some applications, constrained workspaces limit the position and orientation of the patient, and can be difficult to access tools, electrical equipment, and other equipment. Medical instruments, including air wires and tubes, may be blocked from reaching the patient, and the optical path may be blocked. This makes observation and imaging unclear.

[0007] Non-Patent Document 1 describes eight rotatable magnets for generating magnetic fields and gradients in any direction. A system of permanent magnets is described. Each magnet is oriented perpendicular to its magnetic moment. The position of the magnet and the direction of the rotation axis are determined by the average magnetic field and It is obtained by maximizing a metric that describes the gradients as well as their standard deviations. The authors used the system to control the path of a 250 μm micromagnet.

[0008] Non-Patent Document 2 discloses an array of six magnets arranged equidistantly in a circle. Each magnet is rotatable around an axis extending parallel to the axis of the circle, and the magnetic motor of each magnet is The magnets extend in a direction perpendicular to the axis of rotation. All the magnets rotate synchronously in the same direction, creating a circular motion. A constant intensity, counter-rotating magnetic field is generated in the central area.

[0009] Non-Patent Document 3 describes several compact permanent magnet configurations, which This configuration produces a magnetic field greater than the remanence of the magnetic material that composes them. Halbach hollow cylindrical flux source (HCFS) and hollow sphere It is based on the principle of a hollow spherical flux source (HSFS).

[0010] As seen in Patent Document 1, a magnet assembly capable of adjusting a magnetic field is known. The stone assembly includes at least two rotatably mounted magnets. The rotation of the stone changes the magnetic field generated by the magnet assembly. The intended use of the assembly is The magnets constituting the assembly may be rotated, or the entire assembly may be rotated. A magnetic field of variable direction that is used to magnetically manipulate medical devices inside the body. Other magnet assemblies are disclosed in Patent Documents 2 to 6. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] U.S. Patent No. 6,537,196 [Patent Document 2] U.S. Patent No. 6,157,853 [Patent Document 3] U.S. Patent Application Publication No. 2008 / 016677 [Patent Document 4] European Patent Application Publication No. 1156739 [Patent Document 5] European Patent Application Publication No. 1168974 [Patent Document 6] European Patent Application Publication No. 1030589 [Non-patent literature]

[0012] [Non-Patent Document 1] P Ryan and E Diller, “Five-Degree-of-Freedom Magnetic Control of Micro-Robots Using Rotating Permanent Magnets”, 2016 IEEE International Conference on Robotics and Automation (ICRA), Stockholm, Sweden, 16 to 21 May 2016 [Non-patent document 2] W Zhang et al, “A Novel Method of Arraying Permanent Magnets Circumferentially to Generate a Rotation Magnetic Field”, IEEE Transactions on Magnetics, Vol 44, No 10, October 2008 [Non-patent document 3] HA Leupold and E Potenziani, “Novel High-Field Permanent Magnet Flux Sources” Summary of the Invention [Problem to be solved by the invention]

[0013] An object of the present invention is to provide an improved magnetic field generating device. To provide an improved method for changing at least one characteristic of a magnetic field emanating from a magnet. Finally, it is an object of the present invention to provide uses of the above magnetic field generating device and the above method. It is target. [Means for solving the problem]

[0014] Reference signs in the claims are not intended to imply limitations but are intended to make the claims easier to read. It is merely a means to make things easier.

[0015] According to one aspect of the present invention, the above problem is solved by a magnetic field generating device according to claim 1. The magnetic field generator comprises at least three groups of magnets, each of which has a magnetic moment centered on the axis of rotation. Each group includes at least two magnets. Each group has a direction, and the direction The rotation axis of the magnetic moment of the magnets included in the group extends along the axis. The directions of are linearly independent.

[0016] In the context of the present invention, "linearly independent" with respect to a set of directions The term "is" refers to a vector having a direction included in the set of directions being in the set of directions. All remaining directions involved cannot be defined as linear combinations of vectors with This means that

[0017] In the context of the present invention, the requirement that the magnetic moment extend "along the group direction" There is a direction (the "direction of the group"), and the magnetic field of the magnets included in the group is The tilt of each rotation axis of the air moment is less than 15 degrees (when the circumference is 360 degrees), preferably It is preferably less than 10 degrees, more preferably less than 5 degrees, and even more preferably less than 1 degree. Hereinafter, unless otherwise specified, the term "group" always refers to the aforementioned It means a group with a direction.

[0018] According to a related aspect of the invention, there is provided a method for detecting a magnetic field generated by a magnet, comprising the steps of: The above problem can be solved by changing at least one of the properties of the magnet. From the three groups, the magnetic moment of each magnet is generated by rotating it around the axis of rotation. Each group includes at least two magnets. Each group has a direction along which the group The axes of rotation of the magnetic moments of the magnets in each group are linearly independent.

[0019] In another aspect of the present invention, the above problem is solved by a magnetic field generating device according to claim 2. The magnetic field generating device comprises at least six magnets and a means for inputting a set of control parameters. The magnetic moment of each magnet can rotate around the rotation axis, and in the working space, each magnet The combination of the stones' magnetic fields generates a magnetic field with any direction and any magnetic flux density. The direction and flux density of the resulting magnetic field are determined by the values of fewer than six control parameters.

[0020] In the present invention, the "control parameter" is a scaler. The value of the control parameter may be expressed in any suitable format, for example, as a magnitude or as an electrical signal that digitally encodes the value of the control parameter; It can be provided to a magnetic field generating device.

[0021] In the present invention, a "workspace" is a volume of three-dimensional space. The magnetic field generated is the magnetic field in the working space. The direction and magnetic flux density of the magnetic field generated are Therefore, in the present invention, the "direction and "Magnetic mean direction and magnetic flux density" refers to the arithmetic mean magnetic field direction and arithmetic mean magnetic flux density in the working space. Similarly, the spatial gradient of the magnetic flux density of the resulting magnetic field (see below) is It means the spatial gradient as the arithmetic mean of the magnetic flux density.

[0022] In the context of the present invention, "any direction" with respect to the generated magnetic field means any direction in three-dimensional space. The "any magnetic flux density" in relation to the resulting magnetic field is the difference between zero and the maximum achievable magnetic flux density. In some embodiments of the present invention, the magnetic flux density produced is The maximum achievable magnetic flux density of a field depends on the direction of the resulting magnetic field. The density is determined by the construction details of the magnetic field generator, such as the magnet position and magnetic moment. Therefore, according to this aspect of the invention, the magnetic field generated can be directed in any direction in three-dimensional space. and any magnetic flux density between 0 and the maximum achievable magnetic flux density for each direction. It is possible.

[0023] The requirement that "any direction and any magnetic flux density are determined by the value of the control parameters" The condition is that for any combination of direction and magnetic flux density, the value of the control parameter is at least When one set exists and the set is input to the magnetic field generator, the set of direction and magnetic flux density and prompting the magnetic field generating device to generate a generated magnetic field having the desired alignment at a position in the workspace. In other words, each set of control parameter values determines the direction and flux density of the resulting magnetic field. It is clearly defined.

[0024] In a related aspect of the invention, a magnetic field generated from a magnet according to claim 12 is The above problem is solved by a method for changing at least one property. By rotating at least six magnets around the axis of rotation, the magnetic moment of each magnet can be The resulting magnetic field can have any direction and any magnetic flux density. The direction of the magnetic field and the magnetic flux density depend on the rotation angle of the magnetic moment around each rotation axis. is determined by setting the value derived from the values of a set of less than six control parameters. do.

[0025] In another aspect of the present invention, the above problem is solved by a magnetic field generating device having the features of claim 3. The magnetic field generating device includes at least two groups of magnets, and the magnetic moment of each magnet is Each group contains at least two magnets. Each group has a direction. The rotation axes of the magnetic moments of the magnets in the group extend along this direction. Magnets in the same group are combined so that their magnetic moments can rotate. The magnetic moments rotate simultaneously over the same angle around their respective axes of rotation. Rotate.

[0026] In the context of the present invention, "simultaneously over the same angle" means that the magnetic moments This means that the magnetic moment does not necessarily have to be in the same direction. It does not mean that the magnetic moment rotates in either a clockwise or counterclockwise direction. This does not necessarily mean that the magnetic motors rotate from the same starting angle. The rotation angles of the elements can be offset relative to one another.

[0027] In a related aspect of the invention, at least one of the magnetic fields generated by the magnets according to claim 13 is The above problem is solved by a method for changing one characteristic. The magnetic field is generated by changing the magnetic field of at least two magnets. The magnetic moment of each magnet is generated from the group by rotating it around the axis of rotation. Each group includes at least two magnets. Each group has a direction along which the magnets included in that group are The rotation axis of the magnetic moment of the magnets in the group extends. rotate simultaneously through the same angle around the axis of rotation.

[0028] In another aspect of the present invention, the above problem is solved by a magnetic field generating device having the features of claim 4. The magnetic field generating device includes at least two groups of magnets, and the magnetic moment of each magnet is Each group contains at least two magnets. Each group has a direction. The rotation axes of the magnetic moments of the magnets in the group extend along this direction. Each magnet is located on a side of a parallelepiped or on an intersecting circle of a sphere.

[0029] In other words, for each magnet there exists a parallelepiped having sides on which the magnet is substantially located. Alternatively, there is a periphery that intersects the surface of the ellipsoid, and the magnet is located substantially on that periphery. The "perimeter" of an ellipsoid is the circumference of all points whose geometric centers coincide with the geometric center of the ellipsoid. The term "intersecting circumferences" refers to the curves of other This means that the magnets intersect with each other and are substantially located there. The requirement that the magnet be located on the side or the circumference means that the distance between the magnet and the side or the circumference is This means that the length or circumference is less than 15% of the average diameter.

[0030] In a related aspect of the invention, a method for varying at least one characteristic of the magnetic field produced is provided. The magnetic field is generated from at least two groups of magnets, and the magnetic moment of each magnet is generated. Each group consists of at least two Each group has a direction along which the magnetic moments of the magnets in that group are The rotation axis of the magnet extends along the side of the parallelepiped, and the magnet intersects with the ellipsoid. It is located substantially on the circumference of the circle.

[0031] The achievable advantages of the magnetic field generating device and method according to the present invention are: The resulting magnetic field is one or more of the properties of the magnetic moment of the magnet. The characteristics that can be changed are those that can be changed by rotating the axis. includes the direction of the resulting magnetic field, the magnetic flux density, and the spatial gradient.

[0032] In a further aspect of the invention, the problem is solved by the use according to claim 15. Neither the magnetic field generating apparatus nor the method described above operates a tethered device having a magnetic moment. Alternatively, either the magnetic field generating device or the method may be used to generate a magnetic field. It is used to actuate untethered devices with

[0033] [Preferred embodiment of the present invention] Preferred features of the present invention, which may be applied alone or in combination, are set out below: and in the dependent claims.

[0034] As mentioned above, a group of magnets has a direction, and the magnets contained in that group have a direction. The tilt of each axis of rotation of the magnetic moment of the stone is less than 15 degrees (when the circumference is 360 degrees). In the following, unless otherwise specified, the term "group" always refers to a group having the above mentioned orientation. The tilt of the rotation axis of the magnetic moment of each magnet in the group is preferably less than 10 degrees. , more preferably less than 5 degrees, and even more preferably less than 1 degree.

[0035] In a preferred embodiment of the present invention, the magnetic field generating device comprises at least one group of magnets. , more preferably two groups, more preferably three groups. is rotatable about a rotation axis, and each group contains at least two magnets. In the three cases, the group directions are linearly independent. An achievable advantage of this embodiment of the present invention is that it is possible to obtain a generated magnetic field that A preferred magnetic field generating device has three or less groups.

[0036] The angle between the direction of each group and the direction of other groups is preferably greater than 50 degrees. It is preferable that the angle is less than 65 degrees, and more preferably greater than 70 degrees. In a highly preferred embodiment, the direction of each group is "substantially perpendicular" to the direction of each other group. This means that the direction of each group is perpendicular to the direction of other groups with a deviation of less than 15 degrees. This deviation is more preferably less than 10 degrees, and even more preferably It is less than 5 degrees, and more preferably less than 1 degree.

[0037] Preferably one, more preferably two, and even more preferably three of the groups contain three or more magnets. For example, three, four, five, or six magnets. This embodiment of the invention may be used with more Many magnets produce a more uniform and / or stronger magnetic field or This can be exploited to provide a stronger gradient.

[0038] Preferably, the magnetic field generating device comprises means for inputting a set of control parameters to control the magnetic field to be generated. The direction and magnetic flux density are determined by a set of control parameters. The control parameters are less than six control parameters, more preferably less than five control parameters. In a particularly preferred embodiment of the invention, the number of control parameters is three. This embodiment of the present invention allows for the generation of magnetic fields of any direction and / or any magnetic flux density. and exploiting the fact that three scalar parameters are sufficient to define the magnetic moment. In another preferred embodiment of the present invention, the number of control parameters is two. In this embodiment, two factors are used to determine the direction of the generated magnetic field in two-dimensional space and the arbitrary magnetic flux density. We take advantage of the fact that a scalar parameter of is sufficient.

[0039] The preferred control parameters are those in which the value of each control parameter is greater than or equal to the value of the other control parameter(s). Independent in the sense that they can be selected independently from the values. In this case, the relationship between the direction of the magnetic field and the magnetic flux density and the control parameters is expressed as a bijection. ction).

[0040] In a preferred embodiment of the present invention, the control parameters are: The control parameter is preferably a rotation angle of the magnetic moment around the rotation axis. Each set of data values clearly defines the angle of rotation of the magnetic moment of the magnet. In a preferred embodiment, for each group of magnets, the rotation of the magnetic moments of all magnets in the group is There is one control parameter that determines the angle, and each group has a different control parameter. In this embodiment of the invention, when the direction of the generated magnetic field and the magnetic flux density are considered as vectors, each The group can contribute one component to this vector, and the control parameters control the direction and direction of this component. This utilizes the ability to control the combination of magnetic flux density.

[0041] Preferably, the control parameters do not define the translation of the magnet. The parameter only determines the rotation angle of the magnetic moment of the magnet. In a preferred embodiment, the magnet is not translatable but is fixed relative to the workspace. Thus, in the preferred magnetic field generating device, the rotation angle of the magnetic moment is defines the direction and flux density of the resulting magnetic field.

[0042] The preferred magnets are permanent magnets. Permanent magnets include, for example, neodymium, iron, and boron. Preferably, all magnets in the magnetic field generator are made of a neodymium magnet made of an alloy of Preferably, all magnets in the same group have a coercive force of at least 600 kA / m. More preferably, all magnets in the same group have the same coercivity. Alternatively, all magnets in all groups have the same standard manufacturing precision.

[0043] The magnetic moment of at least one magnet, and preferably all magnets in the group, is directed towards the axis of rotation. In this context, "substantially perpendicular" means that the magnetic moment is , which means that the axis of rotation extends perpendicular to the axis of rotation with a deviation of less than 15 degrees. , more preferably less than 10 degrees, more preferably less than 5 degrees, and even more preferably less than 1 degree. .

[0044] Preferably, at least one group of magnets has a "hub" and all of the magnets in that group The magnets are at the same distance to the hub of the group. More preferably, all groups have their own hub. Particularly preferably, the hubs of the various groups of magnetic field generators coincide. At least one group of stones has a "plane" and all magnets in that group are positioned on that plane. More preferably, all groups each have a plane. When a group has a hub and a plane, Note that the magnets in the group are arranged in a circle. The stones are spaced equidistantly, meaning that every magnet in the group is connected to the nearest magnet in the group. Therefore, in a particularly preferred embodiment of the present invention, In the group, all magnets are arranged in a circle and equidistantly.

[0045] Preferably, the magnetic moment of at least one magnet, preferably all magnets, is in particular If the magnet is a permanent magnet, the magnet is rotated around the axis of rotation of each of the magnetic moments. The magnet is preferably driven by an electric motor. However, the present invention also includes embodiments in which the magnetic moment is rotated by other means, such as , the magnetic moment of an electromagnet with multiple electrical loops or coils is It can be varied by changing the current supplied to the coil's electromagnet.

[0046] In a preferred embodiment of the present invention, in at least one group, the magnets in the group The magnetic moments of the magnets are combined in a rotating manner, The magnetic moments rotate simultaneously through the same angle around their respective axes of rotation. More preferably, in all groups, the magnets in each group are combined to operate in this manner. Preferably, the simultaneous movement of all operatively associated magnets in a group is In another embodiment of the present invention, some magnets, e.g. For example, half of the magnets rotate in one direction and the other magnets, e.g., the remaining half, rotate in the opposite direction. In other words, some magnets rotate clockwise and others counterclockwise. Thus, a plurality of magnets are operatively combined.

[0047] In a preferred embodiment of the present invention, to achieve simultaneous transfer of magnetic moments, Two or more magnets, most preferably all magnets, are connected to each other and / or to gearing, Chain, belt, or other mechanical transmission, e.g., cogwheel drive, scooter Connected to the motor by a drive, belt drive, or a combination of both .

[0048] Preferably, at least one group has a "center" and the magnets of any pair of magnets in that group are The rotation angle of the magnetic moment around each axis of rotation of the magnetic moment is determined by a certain coefficient and its group offset by a value that is the product of the angular distance of the rotation axes of the two magnetic moments measured from the center of the The factor is preferably 2. "Angular distance" means the distance from the center perpendicular to the group direction. The angular distance is measured in a plane perpendicular to the magnetic field. The lines extending to the intersection of the rotation axis of each magnetic moment of the pair of magnetic moments with the measurement plane are More preferably, all groups have a center. Preferably, at least one Each group, more preferably all groups, has a hub and a center, and even more preferably the two coincide. Preferably, at least one group, more preferably all groups, have a plane and a center. , and even more preferably, the plane and the measurement plane coincide.

[0049] Preferably, in at least one group, and more preferably in all groups, the magnets are , located substantially on the sides of a parallelepiped or on intersecting peripheries of a substantially ellipsoid. The parallelepiped is preferably a rectangular parallelepiped, and particularly preferably a cube. An ellipsoid is preferred. The working space is preferably a parallelepiped. A possible advantage of this embodiment of the invention is that the working space are obtained from six windows defined by the six faces of a parallelepiped, or from the intersecting perimeter of an ellipsoid. It is freely accessible from the six windows between the two.

[0050] In the case of a parallelepiped, including a rectangular parallelepiped or a cube, the magnets are preferably located in the sides of the parallelepiped. In this context, "near the center" means closer to the edge of the magnet than the center of gravity. The distance to the edge is greater than 70% of the distance from the center of gravity of the magnet to the far right edge of the edge. It means that the ratio is more preferably greater than 80%, and even more preferably greater than 90%.

[0051] In an exemplary embodiment of the present invention, the direction, hub, plane, center, measurement plane, It should be understood by those skilled in the art that the circles, edges, and spheres are imaginary and not physically embodied. Those skilled in the art will appreciate that the present invention nevertheless includes the possibility that one or more of these may be used in combination, e.g. , which can be seen as the physical equivalent of shafts, beams, panels, and hole forms for manufacturing purposes. Embodiments are also included.

[0052] The working space from the combined magnets in each of the possible directions of the resulting magnetic field The maximum achievable magnetic flux density of the magnetic field generated between the As mentioned above, the "magnetic flux density of the magnetic field generated" in the work space is the magnetic flux density generated in the work space. Preferably, the magnetic flux density of the magnetic field generated within the working space is uniform, which is the magnetic flux density of the magnetic field generated in the working space (i.e., the magnetic flux as the arithmetic mean in the working space) density) by more than 20%, preferably by more than 10%, more preferably by 5% This means that there is no point in the workspace where the magnetic flux density deviates by more than Or, the direction of the magnetic field generated in the working space is uniform, which means that the magnetic field generated in the working space from the field direction (i.e., the direction as the arithmetic mean in the working space) by more than 10% Preferably, this means that there are no points in the workspace where the magnetic field direction is misaligned by more than 5%. Preferably, the working space is 1 cm 3 (cubic centimeters) greater volume The direction of the resulting magnetic field is preferably greater than 0.1 degrees per second, more preferably greater than 1 It can change at a rate greater than degrees per second.

[0053] In a preferred embodiment of the present invention, the magnetic moment of one or more of the magnets By rotating the magnets, the magnetic flux density of the magnetic field generated in the working space by the combined magnets is Preferably, the direction and flux density of the resulting magnetic field are controlled by a set of controls. The direction of the spatial gradient is preferably greater than 0.1 degrees / second. The angle can be changed at a rate of 1 degree per second or more preferably at a rate of 1 degree per second or more.

[0054] The magnetic field generating apparatus or method described above preferably comprises a tethered device having a magnetic moment. Alternatively, any of the above magnetic field generating devices or methods may be used to generate magnetic Used to actuate untethered devices with moment. "ered" means that the medical device is physically (i.e., substantially) outside the workspace. "Tethered" on the other hand means that the workspace is not connected. Refers to a device or tool that is physically (i.e., substantially) connected to the outside world.

[0055] Preferably, the magnetic field generating device and method are for use in or within a biological tissue or organ or lumen or animal. It is used to activate and operate small devices inside the human body. In a preferred embodiment, the magnetic field generating device may be a small propeller, a stent, an implant, a particle child, magnet, actuator, end effector, robot, grasper, lens, needle, tube actuate and manipulate optics, endoscopes, catheters, optical fibers, electrical wires, or medical devices It is used to create

[0056] More preferred embodiments of the present invention will be described below. However, the present invention is not limited to these examples. It is not something that is done. [Brief explanation of the drawings]

[0057] [Figure 1] FIG. 1 is a perspective view of a magnetic field generating device having a cylindrical magnet. [Figure 2]FIG. 1 is a perspective view of a magnetic field generating device having a cubic magnet. [Figure 3] This is a cross-sectional view through one group of permanent magnets in the magnetic field generator of Figure 1. Magnetic moments M1, M2, M3, and M4 are the same magnitude within manufacturing tolerances, and all of the magnetic moments extend along the plane of the page. However, these magnetic moments have different rotation angles α1, α2, α3, and α4 with respect to a rotation axis extending perpendicular to the page. Furthermore, all of the magnetic moments rotate at angular velocities whose absolute values are |ω|, but two magnetic moments rotate clockwise while the other two rotate counterclockwise. [Figure 4] 1 is an illustration of a magnetic field generating apparatus having three groups of magnets for actuating an untethered medical device inside the human body, the top left image is a top view, the top right image is a side view, and the bottom image is a front view. [Figure 5] 1 is an illustration of a magnetic field generating apparatus having three groups of magnets for actuating a tethered medical device inside the human body, the top left image is a top view, the top right image is a side view, and the bottom image is a front view. [Figure 6] Components of the generated magnetic field measured in the workspace generated by a group of four rotating magnets. The magnets are spherical, 30 mm in diameter, and have a coercive force of approximately 955 kA / m. The generated magnetic field is a spatially uniform 20 mT field, rotating at 1 Hz from approximately 1 s. [Figure 7] This is a comparison of the measurement results of the maximum magnetic field generated by the magnet group and the simulation results. [Figure 8] Simulation results of the generated magnetic field oscillating along the z-axis. [Figure 9] Figure 1 shows the simulated results ("Sim") and measured results ("Exp") of an oscillating generated magnetic field B(G) with three directions in the xy plane: (a) αB=0°, (b) αB=45°, (c) αB=90°. The magnetic field components in the x and z directions are labeled "Bx" and "Bz", respectively. The curves are the simulated results (labeled "Sim"), and the symbols are the experimental results (labeled "Exp"). [Figure 10] (a) An explanatory diagram showing the component vectors Bx, By, and Bz of the generated magnetic field B along the axes of a coordinate system, and the angles that determine the direction of the magnetic field vector in the same coordinate system. (b) An explanatory diagram of the three magnetic fields Bxy, Bxz, and Byz that are generated by the magnetic moments of the three magnet groups, respectively. The directions of the latter three magnetic fields are determined by the angles αxy, αxz, and αyz, respectively. [Figure 11] FIG. 1 is a cross-sectional view in the yz plane of a group of four permanent magnets that generate a magnetic field Byz. [Figure 12] A cross-sectional view in the yz plane of a group of five permanent magnets that generates a magnetic field Byz. (a) is a cross-sectional view of the array. (b) is the result of a numerical simulation verifying the rotating magnetic field. The arrows in the simulation indicate the direction of the magnetic field, and the length of the arrow corresponds to the magnetic field strength. [Figure 13] In tree-dimensional space, the vector

number

[0058] In the following description of preferred embodiments of the present invention, identical reference numerals refer to identical or similar elements. Indicates the element.

[0059] [Example: A magnetic field generator with 12 magnets] The magnetic field generating device shown in FIGS. 1 to 3 has three groups of a plurality of permanent magnets 1, and each group has four The magnets 1 in the drawing are cylindrical or cubic in shape, but may be of other shapes. The permanent magnets 1 may be arranged in a shape such as a sphere or a rectangular parallelepiped. The permanent magnets 1 have a magnetization strength and a permanent magnetization direction. The magnetic moment M of the magnets 1 is i The magnet is configured to rotate by an electric motor (not shown) about an axis perpendicular to the axis of rotation. The magnetic field 2 generated by the magnetic field vector B is generated at the center of the magnetic field generating device where the workspace 3 is located. occurs.

[0060] In many applications, a uniform magnetic field 2 with negligible field gradient forces is applied to a large working space. In the magnetic field generating device of FIGS. 1 to 3, the magnet 1 is The hub is positioned in the center of the workspace 3 so that the distances to the adjacent magnets are equal. The magnetic field 2 is arranged in a circle around the magnet, minimizing the spatial and temporal gradient of the generated magnetic field 2. 1. When the magnetization of multiple magnets 1 is different, in principle, the arrangement of multiple magnets 1 can In this case, the magnets 1 are no longer separated from the hub. It is not at the same distance or is no longer equidistant from its neighboring magnets.

[0061] Advantageously, in the configurations of FIGS. 1 to 3, the magnetic field B can be adjusted while also allowing for adjustment of the magnetic flux density of the magnetic field B. To change the direction of vector B to point in any direction in three-dimensional space, we use three independent Only the angular inputs (shown as α, β, and γ in Figures 1 and 2) are required. can be zero, but the maximum magnetic field achievable depending on the direction of the vector B The magnetic field generating devices shown in Figures 1 to 3 have a total of There are 12 magnets (3 groups x 4 magnets per group), but 3 independent rotation inputs Only one motor is required, and therefore only three motors are required for the setup.

[0062] Each group has at least two magnets (located on opposite sides of the workspace). There may be five or more magnets 1. The more magnets 1 there are, the larger the workspace 3. A higher magnetic flux density is obtained over a wide area. The magnet 1 does not require a direct connection to the belt drive, gear drive, or other An actuation means may be included.

[0063] The magnets 1 are placed on the sides of the cube, so that the workspace 3 can be accessed from many directions. Only one rotational degree of freedom is required for each magnet 1, and the magnet 1 can be translated. This design feature allows for a change in the magnetic field 2 to be realized. This design feature also allows for long-term accessibility to workspace 2. As shown in Figure 2 by the large hollow arrows, the workspace 3 contains four magnets 1. This allows access from the sides as well as from the top and bottom. 4 and 5. A patient 11 is placed in the patient access section 1 The patient can be placed on a sliding bed in the magnetic field generator by means of the anesthesia tube. The valve, intravenous (IV) injections, and electrical sensor 12 are operable. The patient 11 can remain connected to the device while the device is in use. Computer tomography (CT), ultrasound, light, etc.) It is also possible to do so from the imaging access unit 13 on the surface.

[0064] The possible uses of the present invention are: (1) the methods described in, for example, EP 17166356 and As disclosed in US Pat. No. 17,187,924, the invention provides a method for the migration or penetration of biological fluids or tissues. (2) driving a propeller or robot that cuts through biological tissue; (3) steering an endoscope or catheter within a body lumen. (3) to drive wireless miniaturized actuators; (4) for biological research or For example, magnetic microscopy can be used for intracellular delivery or for microrheological studies. (5) magnetically steering electron beams. However, this is not limited to this.

[0065] [Example: Operation of a medical device inside the human body] An exemplary application of the disclosed invention is the use of a generated magnetic field to stimulate medical devices inside the human body. Figures 4 and 5 show the operation of an untethered medical device. Two embodiments are shown for actuating a medical device and a tethered medical instrument, respectively. The space has a connection to a physical device, such as a cable, that leads to the outside of the workspace. An untethered medical device does not have such a connection.

[0066] In FIG. 4, an untethered medical device 15 operates within a workspace 3 using a magnetic field 2. The device 15 has a finite magnetic field (e.g., due to a permanent magnet attached to the device). Since they have a magnetic moment, they tend to align in the direction of the external magnetic field 2. The magnetic field 2 can be used to apply a torque to the medical device 15, The device 15 operates in this way. The device 15 may be of any suitable shape, e.g., translation during rotation. The device 15 may have the shape of a spiral propeller to allow for magnetic movement. The device is configured with multiple magnetic moments so that the shape of the device changes under the application of field 2. For example, the medical device may have a grasper that opens and closes or can be a stent, a valve that opens and closes, or a pump that moves periodically.

[0067] In FIG. 5, a tethered flexible medical device 15 is manipulated within a workspace 3 by a magnetic field 2 . A body part of the patient 11 (in the example of FIG. 5, the head for neurosurgery) is connected to the access part 1. 6. Surgical tools 15 can be placed in the workspace via another access 14. The tip of 15 is a permanent magnetic motor (e.g., by a permanent magnet encapsulated in the tip). (This permanent magnet moment is along the long axis of the instrument 15.) ), the tip can be oriented in the direction of the external magnetic field 2, thus forming the instrument 15 The direction of the tip of the flexible instrument is controlled by the disclosed method. 15 includes endoscopes, catheters, optical fibers, optical fiber bundles, tubes, wires, graspers, Or it may be any other suitable device.

[0068] The present invention relates to an active device for ablating through biological tissue, e.g. In order to operate an optical fiber that transmits laser light (e.g., pulsed laser light) It can be used for

[0069] The parts of the human or animal body that are placed in the magnetic field generating device include the head, brain, eyes, arms, legs, knees, It can be a hand, a foot, or any other desired part of the body (whole or part). The position of the patient 11 can be adjusted relative to the device inside the human body, i.e. Monitoring of the instrument 15 is performed by a suitable medical imaging modality. The position information of the tip of the instrument 15 is used in a feedback control loop to drive the magnetic field generator. The relative position of the patient 11 and the magnetic field generator is , the tip of the device 15 or instrument 15 is placed sufficiently inside the working space 3, for example, at its center. Alternatively, the working space 3 of the magnetic field generator can be adjusted to keep it close to the device. Since the range of movement required for the device 15 is larger than that required for the device 15, the position of the patient 11 relative to the magnetic field generator and fixed in place.

[0070] The device or instrument 15 can be used to extract solid or liquid biological tissue, e.g., brain, liver, prostate, muscle, On the skin, in the eyes, or in certain organs, or in the body, such as the ureters, kidneys, bladder, eyes, heart, stomach, lungs, blood vessels, etc. It may operate or operate within a body lumen or within any other suitable biological tissue.

[0071] The device may be adapted to move in accordance with the present invention while an additional external force is applied to the tethered medical device. In this embodiment, the magnetic field generating device or method may be operated by The biodevice may be configured such that the force required to penetrate tissue or other biological material is provided by other means. Control the direction while holding.

[0072] The magnetic field generating device or method according to the present invention has several advantages: a) it is Potentially a wireless approach, thus allowing greater flexibility for the medical device 15 b) The workspace 3 is large enough to accommodate a human body or part of a human body. c) Higher magnetic flux density is achieved, resulting in greater actuation force or d) Access 16 to workspace 3 allows for positioning of patient 11; Other medical devices, such as IV tubing 12, anesthesia tubing 12, and sensors 12, can be connected and and medical imaging instruments 13 and surgical tools 14, e.g. For example, scalpels, scissors, and needles can be applied.

[0073] [Analytical theory for generating superposed magnetic fields] The present invention generates a magnetic field 2 in a workspace 3, the magnetic field strength and direction of which are controlled. To explain the theory behind the present invention, we will first consider a magnet 1. This describes the situation where a single group of magnetic fields generates a generated magnetic field 2 with a constant strength and continuously changing direction. Next, a group of magnets 1 generates a generated magnetic field 2 with oscillating strength and a constant direction. Finally, we will explain the generated magnetic field 2 having an arbitrary direction and magnetic flux density.

[0074] [Spatially uniform and rotating generated magnetic field] In this embodiment, four magnets 1 are arranged in a group to control the generated magnetic field 2 in the plane. These magnets 1 have the same magnitude of magnetic moment and are adjacent to each other. The magnets are spaced equally apart and are positioned at the same distance from the hub of the group. The spatially uniform magnetic field 2 in the working space is expressed by the following equation:

number

[0075] Each permanent magnet 1 is a cylindrical or disc-shaped magnet 1, and as shown in FIG. 3, the magnetic field is distributed in the radial direction. It has a dipole and rotates about its cylindrical axis (along the x-axis and perpendicular to the dipole moment) The magnetization vector Mi is in the yz plane at an angle α i At point p, there are four dipoles The vector B of magnetic field 2 generated by the superposition of magnetic fields generated by the electrons is as follows: is.

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[0076] The magnetic moments of the magnets 1 are arranged in pairs at diagonal positions, i.e., M1 and M4. While aligning the pair with the pair of M2 and M3, the two pairs are in opposite directions ( When the phase difference is 180 degrees, the maximum magnetic field strength is obtained. From this state, magnet 1 is mechanically rotated clockwise at the same angular velocity ( α B =α B0-ωt), the magnetic field of magnet 1 rotates with the same angular velocity ω but counterclockwise. The rotation angle is φ=ωt.

number

[0077] The measured generated magnetic field 2 follows theoretical predictions. As shown in Figure 6, the magnetic field 2 in the y and z directions The components oscillate with a phase difference of π / 2, and therefore the combined magnetic field has a constant strength. The coercive force of each spherical magnet, which has a diameter of 30 mm, is approximately 955 kA / m. The maximum magnetic field B obtained by this setting max As shown in Figure 7, the distance between the magnets is also measured. The measurements fit the simulations very well, and the maximum The strength exceeds 500G at this setting.

[0078] [Magnetic field oscillating along a given axis] The oscillating generated magnetic field 2 is at an angle α to the y-axis. B Fixed vibration axis (direction) determined as and the magnetic field strength oscillates, which can be expressed as:

number

[0079] The geometry and initial conditions of the setup are the same in equations (3) to (5). The difference is In particular, as shown in Figure 3, M1 and M2 rotate in opposite directions. M1 and M2 rotate clockwise with angular velocity -ω, and M2 and M3 rotate counterclockwise with angular velocity ω. Since the vibration angle is φ=ωt, the rotation angle of the four magnets 1 is expressed as follows: do.

number

[0080] This approach results in two outputs: the magnetic field generated at the hub of the group of magnets 1; The magnitude and direction of field 2 is completely controlled by two independent inputs α 0 and φ.

[0081] The simulation results of the magnetic flux density are shown in FIG. B = The example shows the generated magnetic field 2 oscillating at a distance of 120 mm. from a maximum of approximately 374 G at a distance of 110 mm to a maximum of approximately 485 G at a distance of 110 mm, The simulation also showed that the force increases nonlinearly to a maximum value of approximately 645 G at 100 mm. This is shown by the same magnet 2, both of which have a relatively small diameter of 30 mm. This simulation clearly demonstrates the advantages of the permanent magnet 1 setup over the electromagnet. This is clearly shown because the magnetic field does not require special cooling or expensive power amplifiers. It is possible to easily achieve a strength three to six times that of a general electromagnet without the need for a system. The magnetic field 2 generated at the hub is measured by a Gauss meter and is shown in Figure 9. The experimental results are in excellent agreement with the simulations.

[0082] [Generated magnetic field with arbitrary direction and magnetic flux density] The magnetic field generating device disclosed in this specification can generate any magnetic field within a three-dimensional space surrounded by a magnet 1. It is also possible to generate a vector B of magnetic field 2 pointing in the direction, and to control the magnitude of the generated magnetic field 2. The direction and strength of the generated magnetic field can be controlled by three independent angle controls for each group of magnets. The control parameters (shown as α, β, and γ in Figures 1 and 2) are completely controlled. At the same time, the magnetic flux density of the generated magnetic field B ranges from zero to the maximum achievable magnetic flux density. is adjusted within the range.

[0083] The desired generated magnetic field 2 in the workspace is:

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[0084] The generated magnetic field 2 is composed of three magnets 1, each of which is perpendicular to the other magnets 1, as shown below. is the sum of the magnetic vectors of

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[0085] In some embodiments, the same size, same magnetic moment, and from the hub of the group If magnets 1 are used at the same distance, and the magnetic field strength is equal in each direction, then equation (16) can be written as: B xy =B xz =B yz Simplify by =B1. Match equations (15) and (17). By doing this, the following formula is obtained:

number

[0086] The right side of equation (17) is the three parameters B0, θ W , φ W The required generated magnetic field By defining the field and solving equation (18), the three unknown parameters α xy , α xz , α yz From the viewpoint of controlling the instrument, the three input parameters α x y , α xz , α yz is the three output parameters as the magnitude and 3D direction of the magnetic field vector. Data B0, θ W , φ W In some embodiments, formula (18) provides complete control of is solved numerically using Matlab (R2017a, MathWorks).

[0087] In some embodiments, the magnet groups are not orthogonal to each other, but equation (16) still holds. The decomposition of each magnetic field vector into three axes also gives a new set of equations (17) and (18). However, the general principles are the same as those presented here. Three input parameters α of angles in two directions .. By controlling the magnetic field vector Three output parameters B0, θ as magnitude and 3D direction W , φ W Gives you complete control of Glass.

[0088] The angle α solved for each direction .. The angle of each magnet 1 in the group is determined in the following way: For example, as shown in FIG. 11, if there are four permanent magnets in one group, Consider the cross section of each group with n=4. In this embodiment, each magnet 1 is The i-th rotation is made around the axis perpendicular to the axis of rotation (x-axis in this case) with the same angular velocity ω. Magnet rotation angle β i follows the relationship:

number

[0089] Equation (19) is true if the number of magnets 1 in each group is two or more (n≧2), and the number is odd. This always holds true whether the number is even or even. Figure 12 shows an example with five magnets. The length of the side of the magnet is 30 mm, and the center point of the magnet is placed on a circle with a diameter of 70 mm. The angle of each magnet is calculated using equation (19), and the structure is then The results were verified by finite element simulation (Comsol multiphysics 5.2a, Comsol). In Figure 12b, a series of images shows the simulation results at 90 degree intervals. 2 is uniform in time and space in the workspace 3. Five magnets 1 are The magnetic field rotates counterclockwise as it rotates clockwise. do.

[0090] In another embodiment, it is necessary to create a rotating generated magnetic field 2. is spatially and temporally uniform in magnetic field strength, and the magnetic field direction is defined in three dimensions. As shown in Figure 13, the rotation axis is the unit vector

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[0091] The rotating magnetic field vector is a function of time as follows:

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[0092] [Generation of a three-dimensional magnetic field by a group of magnets on a rotating stage] A group of four magnets 1 provides a rotating magnetic field in a plane (as shown in Figure 3). To realize three-dimensional manipulation of the rotation axis of the magnetic field, the magnet is The stage is mounted on a rotation stage with two degrees of freedom (DoF). The entire setup (relative to the patient) is rotated in two directions β and γ. The points are: 1) Access to the workspace is limited to one direction only, i.e., the γ axis. However, access along another direction, e.g., the β axis, is always possible. 2) the rotation of the entire device drives the magnet 1 3) the overall device requires a large amount of rotation. Electrical power is required, increasing the risk to the patient 11 or the operator.

[0093] [Example: Creating a three-dimensional magnetic field using six magnets, each of which can rotate in two directions] As shown in FIG. 15, the spherical permanent magnets 1 are arranged in three groups, each containing two magnets. The magnets in each group rotate simultaneously with 2-DoF. The direction and magnitude of the magnetic vector are It is also possible to achieve complete control of both. Each magnet 1 (magnetic moment) is orthogonal to It is rotatable about two axes (two of the three axes denoted as α, β, and γ).

[0094] [Example: Experimental method for magnetic field generating device] The magnetic setup consisted of four spherical magnets (K-30-C, Neo) with a diameter of 30 mm. The spherical magnet is made by Supermagnete (Jim N40). The magnet is held in a spherical cavity in the custom-made coupler. The orientation of magnet 1 is determined by the clamping force. The four wheels are held together by the large friction induced by the Stepping motor (1.8 degrees / step, stall torque: 0.15 N m, SH3 537-12U40, Sanyo Denki, not shown) with two separate driver boards (US1D2 00P10, 2.0A, 16 divisions, Sanyo Denki, not shown). The initial direction α0 of the four magnets 1 was manually adjusted. After adjusting the magnets 1, they were connected to a function generator (33220A, Agilent, not shown). The motor rotates at the same absolute speed and is controlled by the square wave signal generated by the magnetic torque. Because heat is generated especially when held in a fixed stationary position against the The motor was air-cooled.

[0095] The distance between the diagonal centers of magnet 1 was set to 120 mm. The large magnetic field strength changes. Reducing the distance results in a large magnetic field, which is It also requires a larger driving torque from the motor, which is larger for a specific orientation of magnet 1. This exceeds the stall torque of the motor.

[0096] Measure the magnetic field 2 generated at the center of the magnetic field generator in each of the x and z directions. A digital gaussmeter (HGM09s, MAGSYS) was used to measure the magnetic field 2. The results are plotted as symbols in Figure 7. The measurement was repeated three times. The magnitude was reproducible within ±0.5 G at the same position. Therefore, error bars are not plotted in the figure.

[0097] For magnetic field strength and direction, Comsol 5.2a (Comsol Multiph Simulations were also performed using magnetic insulating boundary conditions. The 3D simulation was carried out within a cubic volume of 0 mm. The spherical magnets 1 were arranged with a center-to-center distance of 120 mm between diagonal corners as shown in FIG. 3a. The relative permeabilities of air and the four spherical magnets 1 are set as 1 and 4000, respectively. The magnetization strength of the stone was set to 955 kA / m, and each direction was calculated according to Equations 6 to 9. Calculated. α B = 0 degrees, 15 degrees, 30 degrees, 45 degrees, 90 degrees, and β = 0 degrees in 10 degree increments A parametric sweep was performed over 360 degrees. The magnetic flux density is shown in grayscale. The direction of the magnetic field is indicated by the arrow in Figure 6.

[0098] [Example: Multiple magnets in one group] In each group there are at least two magnets 1 (placed on opposite sides of the workspace) More magnets result in a higher magnetic flux density over a larger workspace 3. Therefore, there may be five or more magnets 1. The mechanical drive mechanism (not shown) for the magnets 1 is It does not require a direct connection to a specific magnet 1, but can be driven by a belt drive, gear drive, or Any other suitable actuation means may be included.

[0099] Each group of magnets 1 has a flat surface and a hub, and the magnets 1 are equidistant in the circle. The hubs of each group are As shown in Figure 16, the central symmetry axis of each group is perpendicular to the central symmetry axis of the group, but perpendicular to the axes of workspace 3 (in this case, the patient's coordinate system). The three orthogonal groups are not necessarily oriented in the same direction. This allows for complete control of the direction and strength of the magnetic field 2 generated within the workspace 3.

[0100] In one embodiment, a configuration having multiple magnets 1 may be implemented as shown in FIGS. 16 and 17: It can be scaled to human scale. Each group has a diameter of 100mm and a length of 200m. There are 18 magnets 1, each with a diameter of m. The inner diameter (gap) of each group is The rectangular parallelepipeds in Figures 16 and 17 are set to a width of 500 mm, which is suitable for people within the The figure shows the outer bounding box of a human body, with a diameter of 1700 mm, a thickness of 300 mm, and a length of 1700 mm. A finite element analysis of one group of 18 magnets showed a magnetic flux density of 955 kA / m. is uniform in the working space and reaches approximately 448 Gauss.

[0101] [Example: Activating a linear actuator using a magnetic field generator] One application of the oscillating magnetic field generated by the device is the linear magnetic field shown in Figure 18a. The actuator was operated wirelessly. When the external magnetic field was equal to zero, this soft The structure retains its original shape (Figure 18b). When a magnetic field in the z direction is applied, A magnetic torque is applied to the embedded small magnet, and this torque also rotates the soft link mechanism. The actuator is compressed (Fig. 18a). The actuator is reduced to a minimum length of l = 3.7 mm. When pressure is applied, the actuator extends to l = 10.5 mm. The motor achieves a linear displacement of approximately 6.8 mm overall without any external load. is longer than 70% of its original length. The displacement during compression (5.1 mm) is This is much larger than the 0.7mm (0.017 in) because the magnetic torque is nonlinear with the magnet orientation. This is because the angle varies and is greatest when the angle is 90 degrees (close to the situation shown in FIG. 19).

[0102] The load characteristics of the actuator were also tested. Figure 20b shows the maximum displacement as a function of the external load. As the load increases, the displacement decreases nonlinearly due to the variation in the magnet orientation. The output work of the actuator also decreases significantly as the displacement decreases. Further optimization of the structure and matching the elastic modulus of the soft material to the load will improve the actuator's This improves performance. The miniature actuator can exert a maximum force of approximately 84 mN. This small actuator can displace 40% of its own weight while still achieving 10% of the displacement. The soft structure is flat, so it can lift twice as much as the traditional soft structure. It is fully compatible with photolithography processes and therefore allows the fabrication of soft structures to micrometer scale. It is also worth noting that the proposed method can be scaled down to the scale of

[0103] The features set forth in the foregoing description, claims and drawings are intended to provide various embodiments of the present invention. These can be associated individually or in any combination to achieve the following:

Claims

1. at least six magnets and means for inputting a set of control parameters; The magnetic moment of each magnet is rotatable around a rotation axis, and magnetic fields generated by the plurality of magnets are combined in the working space to generate a magnetic field with an arbitrary direction and magnetic flux density; the direction and flux density of the resulting magnetic field are determined by values of a set of control parameters; the set of control parameters includes less than six control parameters; Magnetic field generator.

2. 1. A method of altering at least one characteristic of a magnetic field produced by at least six magnets by rotating the magnetic moment of each magnet about an axis of rotation, comprising: the resulting magnetic field can be of any direction and any magnetic flux density; the direction of the magnetic field and the magnetic flux density produced are determined by setting the rotation angles of the magnetic moments about the axis of rotation to values derived from values in a set of less than six control parameters; method.

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