Propeller and method of moving propeller

Abstract

To provide a method of moving a propeller relative to a medium that at least partially surrounds the propeller.SOLUTION: Provided is a method of moving a propeller 1 relative to a medium that at least partially surrounds the propeller, wherein an actuator induces a rotation of the propeller about a rotational axis 4 of the propeller relative to the medium, and the propeller converts the rotational movement into a movement of the propeller relative to the medium. The aspect ratio of at least one cross section 5 of the propeller, the cross section being associated with the rotational axis of the propeller, is greater than or equal to 3. Also provided are a propeller and a method of making a propeller.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method of moving a propeller relative to a medium that at least partially surrounds the propeller, wherein an actuator induces rotation of the propeller about an axis of rotation of the propeller relative to the medium, and the propeller converts its rotational motion into movement of the propeller relative to the medium. The present invention also relates to a helical or modified helical propeller that converts rotation of the propeller into movement of the propeller relative to the medium. Further, the present invention relates to a method of manufacturing a propeller.

Background Art

[0002] In many applications in medicine and biology, it would be advantageous if it were possible to pass through biological media, including biological fluids and soft tissues. For example, in minimally invasive procedures such as targeted delivery of substances or minimally invasive surgery, it is desirable to move a small untethered device through the medium. This is because such methods are less invasive and provide better control than methods using large or tethered devices.

[0003] Small untethered devices have already been reported in the literature. For example, Non-Patent Document 1 (A Ghosh and P Fischer: "Controlled Propulsion of Artificial Magnetically Nanostructured Propellers", Nano Letters, vol 9, pp 2243-2245, 2009) and the supporting information published together with this document reveal that rotation in a cork-screw-like shape provides forward propulsion in a fluid. The rotation is caused by a rotating magnetic field. This concept is also described in Patent Document 1. are carried. Swimming objects having somewhat different shapes are described in Non-Patent Document 2 (L Zhang, J J Abb ott, L X Dong, B E Kratochvil, D Bell, and B J Nelson: "Artificial Bacterial Flagella: Fabrication and Magnetic Control", Applied Physics Letters, vol 94, p 064107, 2009). This swimming object is also driven by rotating a magnetic field. Non-Patent Document 3 (K Ishiya ma, M Sendoh, A Yamazaki and K I Arai: "Swimming Micromechanisms Driven by Magnetic Torque", Sensors and Actuators A: Physical, vol 91, pp 141-144, 2001) describes a screw having a length of several millimeters passing through a porcine tissue (meat) sample when rotating by a rotating magnetic field Non-Patent Document 4 (T Qiu, J Gibbs, D Schamel, A Mark, U Choudhury, and P Fischer: "From Nanohelices to Magnetically Actuated Microdrills: A Universal Platform for Some of the Smallest Unconnected Microrobot Systems in a Low Reynolds Number Biological Environment", Nanometers to Millimeters Scale Size Robot Systems and Applications: vol 8336, I Paprotny and S Bergbreiter, 1st ed Berlin: Springer, pp 53-65, 2 014) describes the fabrication of corkscrew-shaped propellers by oblique deposition (GLAD) and the fabrication of propellers similar to conventional screws by microextrusion molding. This document is also carried

[0004] ​​​​​​​Also, the movement of the propeller within the agarose gel when the propeller is actuated by a rotating magnetic field is described. is described.

[0005] In all of the above disclosures, the propeller has a portion where a permanent magnet moment orthogonal to its major axis acts, or is attached to a permanent magnet. By applying an external rotating magnetic field, torque is given to rotate the uncoupled propeller, and translational movement of the propeller through the medium will also occur. is attached to a permanent magnet. By applying an external rotating magnetic field, torque is given to rotate the uncoupled propeller, and translational movement of the propeller through the medium will also occur. is attached to a permanent magnet. By applying an external rotating magnetic field, torque is given to rotate the uncoupled propeller, and translational movement of the propeller through the medium will also occur. will occur.

[0006] Patent Document 2 discloses a medical device inserted into a patient's organ, which is repeatedly moved by an external magnetic field. Patent Document 3 discloses nanoparticles that move along the gradient of a magnetic field generated from a permanent magnet or an electromagnet. The nanoparticles have a strong tendency to adhere to target cells. An electric field is applied to these nanoparticles to produce an effect sufficient to kill the target cells. Patent Document 4 discloses a handheld automated biopsy device having a drill-shaped tip. This device can be rotated by an actuator. Patent Document 2 discloses a medical device inserted into a patient's organ, which is repeatedly moved by an external magnetic field. Patent Document 3 discloses nanoparticles that move along the gradient of a magnetic field generated from a permanent magnet or an electromagnet. The nanoparticles have a strong tendency to adhere to target cells. An electric field is applied to these nanoparticles to produce an effect sufficient to kill the target cells. Patent Document 4 discloses a handheld automated biopsy device having a drill-shaped tip. This device can be rotated by an actuator. Patent Document 3 discloses nanoparticles that move along the gradient of a magnetic field generated from a permanent magnet or an electromagnet. The nanoparticles have a strong tendency to adhere to target cells. An electric field is applied to these nanoparticles to produce an effect sufficient to kill the target cells. Patent Document 4 discloses a handheld automated biopsy device having a drill-shaped tip. This device can be rotated by an actuator. Patent Document 3 discloses nanoparticles that move along the gradient of a magnetic field generated from a permanent magnet or an electromagnet. The nanoparticles have a strong tendency to adhere to target cells. An electric field is applied to these nanoparticles to produce an effect sufficient to kill the target cells. Patent Document 4 discloses a handheld automated biopsy device having a drill-shaped tip. This device can be rotated by an actuator. Patent Document 4 discloses a handheld automated biopsy device having a drill-shaped tip. This device can be rotated by an actuator. Patent Document 4 discloses a handheld automated biopsy device having a drill-shaped tip. This device can be rotated by an actuator.

[0007] Patent Document 5 discloses a medical implant device implanted in a human or animal body. This device includes intertwined helical wires, and one of these wires is screwed into the tissue during rotation. Patent Document 6 discloses a catheter system having a male thread, and the catheter system advances into the body passage by rotation. Patent Document 7 discloses a surgical device that penetrates into tissue. The distal tip of the device is at least partially covered by a cloth, and by rotating this cloth, the device is made to penetrate into the tissue. Patent Document 5 discloses a medical implant device implanted in a human or animal body. This device includes intertwined helical wires, and one of these wires is screwed into the tissue during rotation. Patent Document 6 discloses a catheter system having a male thread, and the catheter system advances into the body passage by rotation. Patent Document 7 discloses a surgical device that penetrates into tissue. The distal tip of the device is at least partially covered by a cloth, and by rotating this cloth, the device is made to penetrate into the tissue. Patent Document 5 discloses a medical implant device implanted in a human or animal body. This device includes intertwined helical wires, and one of these wires is screwed into the tissue during rotation. Patent Document 6 discloses a catheter system having a male thread, and the catheter system advances into the body passage by rotation. Patent Document 7 discloses a surgical device that penetrates into tissue. The distal tip of the device is at least partially covered by a cloth, and by rotating this cloth, the device is made to penetrate into the tissue. Patent Document 6 discloses a catheter system having a male thread, and the catheter system advances into the body passage by rotation. Patent Document 7 discloses a surgical device that penetrates into tissue. The distal tip of the device is at least partially covered by a cloth, and by rotating this cloth, the device is made to penetrate into the tissue. Patent Document 7 discloses a surgical device that penetrates into tissue. The distal tip of the device is at least partially covered by a cloth, and by rotating this cloth, the device is made to penetrate into the tissue. Patent Document 7 discloses a surgical device that penetrates into tissue. The distal tip of the device is at least partially covered by a cloth, and by rotating this cloth, the device is made to penetrate into the tissue.

[0008] The issue is to further miniaturize existing devices. Furthermore, it has been found that it is difficult to obtain propulsion in viscoelastic media by existing devices. The well-known corkscrew shape functions well in viscous liquids such as water or glycerol and elastic solids such as agarose and meat. However, many important tissues in the biomedical field are neither completely viscous fluids nor completely elastic solids. Rather, these tissues are viscoelastic media that exhibit the combined properties of both liquids and solids. The inventors have found that the well-known propeller shape is insufficient in viscoelastic media.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Patent Document 7

Non-Patent Documents

[0010]

Non-Patent Document 1

[0011] The object of the present invention is to provide a method for moving a propeller relative to a medium that at least partially surrounds the propeller. The improved method of rotating a propeller relative to a medium, comprising: The rotation of the propeller is induced by the medium, and the propeller rotates in a circular motion. Another object of the present invention is to provide a method for converting an improved helical or modified A modified helical propeller that converts the rotational motion of the propeller into the movement of the propeller relative to the medium. The present invention also provides an improved or modified helical propeller that converts It is an object of the present invention to provide an improved propeller. The object of the present invention is to provide an improved method for manufacturing a roper. The present invention can address one or more of the above-mentioned problems. [Means for solving the problem]

[0012] According to one aspect of the present invention, the above problem is solved by providing a medium at least partially surrounding the propeller. This is addressed by providing a method for moving the propeller relative to the actuator. The force induces a rotation about the propeller's axis of rotation relative to the medium, and the propeller continues its rotational motion. and converting the motion of the propeller relative to the medium. Also, at least one cross-section of the propeller, The aspect ratio of the cross section associated with the propeller's axis of rotation is 3 or greater.

[0013] The inventors believe that such a large aspect ratio can be a driving force, especially in viscoelastic media. Without being bound by any particular theory, the inventors et al. consider that the present invention effectively utilizes a newly discovered propulsion mechanism that uses elastic deformation of a medium caused by the rotation of a propeller. A large aspect ratio results in large deformation, and thus causes strong propulsion.

[0014] In the context of the present invention, the term "propeller" means a propulsion structure capable of moving a load attached to itself or to it relative to a medium. In the context of the present invention, the "aspect ratio" of a cross-section is the maximum radius of the cross-section divided by the minimum radius of the cross-section, where the radius is the distance from the center of the cross-section to a point on the periphery of the cross-section. The center of the cross-section is the point through which the axis "related" to the cross-section passes through the cross-section. Further, the cross-section is perpendicular to the axis to which the cross-section is related. The periphery of the cross-section is the outer boundary of the cross-section. Thus, if the cross-section is related to the axis of rotation of the propeller, the radius for determining the aspect ratio is the distance from the point where the axis of rotation passes through the cross-section at a right angle to a point on the periphery of the cross-section. Similarly, if the propeller is a helicoid (described below) and its cross-section is related to the helical axis of the propeller, the radius for determining the aspect ratio is the distance from the point where the helical axis passes through the cross-section at a right angle to a point on the periphery of the cross-section.

[0015] In another aspect of the present invention, the above problem is solved by providing a method of moving a propeller relative to a medium that at least partially surrounds the propeller. An actuator induces rotation of the propeller about the axis of rotation of the propeller relative to the medium, and the propeller converts its rotational motion into movement of the propeller relative to the medium. In this aspect of the present invention, the propeller and The part of the medium that is separated from the rest of the medium by the rotation of the propeller and rotates with the propeller is at least one cross-section of a rotating body comprising, and is a cross-section associated with the axis of rotation of the rotating body has an aspect ratio of 3 or more. Advantageously, according to this aspect of the invention, it is possible to rotate the part of the medium separated from the rest of the medium by the rotation of the propeller at the same speed as the propeller

[0016] This embodiment of the invention is based on the discovery by the inventors that a part of the medium is separated from the rest of the medium, for example by adhesion, and as a result rotates with the propeller. The inventors have found that such co-rotation, despite significantly impeding propulsion, enables powerful propulsion to be achieved by the high aspect ratio of the rotating body comprising the propeller and the co-rotating part of the medium. Here too, without being bound by a particular theory, the inventors believe that in the newly discovered propulsion mechanism, propulsion is mainly caused by the elastic deformation of the medium that does not co-rotate with the propeller, and as a result, the aspect ratio of the rotating body comprising the propeller and the co-rotating part of the medium is important for powerful propulsion

[0017] In a further aspect of the invention, the above problem is solved by a helical or modified helical propeller that converts the rotational movement of the propeller into a movement of the propeller relative to a medium that at least partially surrounds the propeller. The aspect ratio of at least one cross-section of the propeller, which is associated with the helical axis of the propeller, is 3 or more

[0018] According to the experiments of the inventors, the helical and modified helical shapes are particularly effective in providing propulsion​​​​​​​​​​​​​ has been found to be suitable. Further, it has also been found that the production of the spiral shape and the modified spiral shape is easy.

[0019] In the context of the present invention, if the three-dimensional shape of a propeller is obtained by extending a certain two-dimensional shape along a curve while rotating the two-dimensional shape, this propeller is "helical" (hereinafter, helical may sometimes be referred to as helix). The two-dimensional shape is extended along a curve (also referred to as the helical axis), and as a result, any two cross-sections of the propeller will coincide with the two-dimensional shape if each cross-section is orthogonal to the curve at the point where the curve passes through the cross-section. The helical axis is a curve, and the two-dimensional shape is extended along this curve. A certain helix is chiral. In the context of the present invention, if the shape of a propeller is different from its mirror image shape, the propeller is "chiral". In other words, a propeller has chirality (asymmetry) if the image that ideally reflects in a plane mirror does not coincide with itself. Also, a propeller can become chiral by the orientation of the magnetic moment with respect to the body of the propeller. Such a propeller is defined as "generalized chiral" in the context of the present invention. Even a propeller having an achiral shape can be made chiral by an appropriately oriented magnetic moment.

[0020] In the context of the present invention, "modified helical" or a modified helix means that the two-dimensional shape does not maintain identity but changes while extending along a curve. ​​​​​​​​​​​ In this regard, it is different from a "helix". Note that "modified helical" may hereinafter also be referred to as "modified helix". The two-dimensional shape development is continuously differentiable (in contrast to being mathematically discontinuous or non-differentiable). For example, the two-dimensional shape may be stretched in a one-dimensional direction, compressed, bent, or balanced and contracted or expanded in the two-dimensional direction. As a result of the latter, for example, a section of a propeller or the entire propeller

[0021] In a further aspect of the present invention, the above problem is a method of manufacturing a propeller, comprising: (1) defining a straight helical axis; (2) preparing a plate extending along the helical axis, wherein at least one cross-section (preferably all cross-sections) of the plate has an aspect ratio of the cross-section associated with the helical axis of 3 or more; and (3) applying torque along the helical axis to the plate to twist the plate into a helical shape. defining a straight helical axis; (2) preparing a plate extending along the helical axis, wherein at least one cross-section (preferably all cross-sections) of the plate has an aspect ratio of the cross-section associated with the helical axis of 3 or more; and (3) applying torque along the helical axis to the plate to twist the plate into a helical shape. defining a straight helical axis; (2) preparing a plate extending along the helical axis, wherein at least one cross-section (preferably all cross-sections) of the plate has an aspect ratio of the cross-section associated with the helical axis of 3 or more; and (3) applying torque along the helical axis to the plate to twist the plate into a helical shape. defining a straight helical axis; (2) preparing a plate extending along the helical axis, wherein at least one cross-section (preferably all cross-sections) of the plate has an aspect ratio of the cross-section associated with the helical axis of 3 or more; and (3) applying torque along the helical axis to the plate to twist the plate into a helical shape. defining a straight helical axis; (2) preparing a plate extending along the helical axis, wherein at least one cross-section (preferably all cross-sections) of the plate has an aspect ratio of the cross-section associated with the helical axis of 3 or more; and (3) applying torque along the helical axis to the plate to twist the plate into a helical shape. This method effectively utilizes the insight of the inventors, such as that a high ratio of width or length to thickness defined by the plate will transition to the aspect ratio of the helix if the helix is twisted by applying torque. The inventors have thus found a method for easily and reliably manufacturing a helical propeller having a high aspect ratio.

[0022]

[0023]

[0023] According to a further aspect of the present invention, the above problem is a method of manufacturing a propeller, comprising: (1 Step of preparing a first structure having a predetermined geometric shape, and (2) the first structure is cast into a second material, the first structure is removed from the second material, and a female mold replica of the first structure is generated; (3) injecting one or more molding materials into the female mold and curing the molding material under predetermined physical and chemical conditions to form a second solid structure body; and (4) detaching the second solid structure from the female mold, thereby obtaining a desired propeller. This is solved by a method including the steps.

[0024] The present invention is advantageously used in medical diagnosis and treatment, for example, endoscopy, biopsy, drug delivery or delivery of grafts or radioactive substances, or local heat generation. For example, the propeller can transfer an active drug attached to the propeller and release the drug at the disease site. In tumor treatment, the propeller advances through normal tissue to the tumor tissue. If the propeller is made of or contains a metallic magnetic material, heat can be generated in the material by induction heating to kill tumor cells. In addition, the propeller can carry a thin flexible tube to the tumor site and continuously deliver a drug to the tumor through the tube. Similarly, the propeller can pull an electrode connected to an electric wire and move to a specific region of the brain to measure or electrically stimulate the electrical signals of neurons.

[0025] Furthermore, the preferred features of the present invention, which may be used alone or in combination, are considered in the dependent claims, the following description, and the drawings.

[0026] In a preferred embodiment of the present invention, at least one cross-section of the propeller, preferably all The aspect of the cross-section is 2 or more, more preferably 3 or more, still more preferably 5 or more, still more preferably 10 or more, still more preferably 20 or more, still more preferably 50 or more, still more preferably 100 or more, and the one or more cross-sections are associated with the rotational axis of the propeller or, alternatively, with the helical axis of the propeller. This embodiment of the invention effectively utilizes the inventors' discovery that a particularly high aspect ratio is associated with particularly powerful propulsion. The cross-section preferably has a continuous shape.

[0027] Preferably, at least one cross-section of the propeller, more preferably each cross-section, which is associated with the rotational axis of the propeller, has a cross-sectional area of at least 50%, more preferably 100%, still more preferably 3 00%, still more preferably 1000% of the cross-sectional area of the portion of the medium that is separated from the remainder of the medium by the rotation of one or more propellers and rotates with the one or more propellers (in the same cross-section ). This embodiment effectively utilizes the inventors' discovery that co-rotating media can potentially impede propulsion, but such impediments can be limited by restricting the amount of co-rotating material. .

[0028] Preferably, in at least one cross-section of the propeller, more preferably in all cross-sections, the rotational axis of the propeller passes through the region of the cross-section, i.e., inside the periphery of the cross-section, and the one or more cross-sections are associated with the rotational axis of the propeller or, alternatively, with the helical axis of the propeller. In other words, in a preferred embodiment of the invention, the rotational axis or the helical axis at least partially passes through the propeller.

[0029] Preferably, at least 20% of the surface area of the propeller, more preferably at least 50 %, more preferably at least 80%, still more preferably at least 95% is less than 3.2 μm, more preferably less than 1.6μm, still more preferably less than 0.4μm, still more preferably less than 0.025μm, still more preferably less than 0.006μm (in accordance with DIN 4760 of the German Institute for Standardization) and has a surface roughness Ra. According to this embodiment of the present invention , advantageously, it is possible to reduce the adhesion of media that impede the movement of the propeller, for example, biological tissues. The surface roughness of the propeller is reduced to minimize the adhesion of media to the surface of the propeller . Preferably, in order to minimize adhesion, at least the surface material of the propeller is metal, an anti-adhesive polymer and / or a biocompatible polymer. A coating may be applied to the surface of the propeller to minimize the adhesion of media to the surface of the propeller. In order to minimize the adhesion of media, a special operating method that causes a large shear on the surface, for example an operating method that results in a sudden start or stop at a large rotation angle or vibration at a large rotation angle may be used. For example, before the propeller is rotated completely, the amplitude can be gradually increased from 10° to 300

[0030] ° and / or the frequency can be gradually increased from 0.1 Hz to 10 Hz to vibrate the propeller. Due to the viscoelasticity of the media, for example the shear-thinning effect, this operating method will reduce the starting torque required for the complete rotation of the propeller .

[0031] ​​​​​​​In a particularly preferred embodiment of the present invention, the low surface roughness is achieved by at least partially coating the surface of the propeller. More preferably, the entire surface of the propeller may be coated. Examples of preferred coating materials include Teflon (registered trademark), PEG (polyethylene glycol), titanium, or combinations thereof. In a preferred embodiment of the present invention, at least one cross-section of a rotating body comprising a propeller and a portion of the medium separated from the rest of the medium by the rotation of the propeller and rotating with the propeller, preferably all cross-sections, and the aspect ratio of the cross-section associated with the axis of rotation of the rotating body is 2 or more, more preferably 3 or more, more preferably 5 or more, more preferably 10 or more, more preferably 20 or more, more preferably 50 or more, more preferably 100 or more. This embodiment of the present invention effectively utilizes the inventors' discovery that strong propulsion is achieved by the high aspect ratio of a rotating body comprising one or more propellers and a co-rotating portion of the medium, even though co-rotation hinders propulsion. The cross-section of the rotating body preferably has a continuous shape. In a preferred embodiment of the present invention, at least one cross-section of a rotating body comprising a propeller and a portion of the medium separated from the rest of the medium by the rotation of the propeller and rotating with the propeller, preferably all cross-sections, and the aspect ratio of the cross-section associated with the axis of rotation of the rotating body is 2 or more, more preferably 3 or more, more preferably 5 or more, more preferably 10 or more, more preferably 20 or more, more preferably 50 or more, more preferably 100 or more. This embodiment of the present invention effectively utilizes the inventors' discovery that strong propulsion is achieved by the high aspect ratio of a rotating body comprising one or more propellers and a co-rotating portion of the medium, even though co-rotation hinders propulsion. The cross-section of the rotating body preferably has a continuous shape. In a preferred embodiment of the present invention, at least one cross-section of a rotating body comprising a propeller and a portion of the medium separated from the rest of the medium by the rotation of the propeller and rotating with the propeller, preferably all cross-sections, and the aspect ratio of the cross-section associated with the axis of rotation of the rotating body is 2 or more, more preferably 3 or more, more preferably 5 or more, more preferably 10 or more, more preferably 20 or more, more preferably 50 or more, more preferably 100 or more. This embodiment of the present invention effectively utilizes the inventors' discovery that strong propulsion is achieved by the high aspect ratio of a rotating body comprising one or more propellers and a co-rotating portion of the medium, even though co-rotation hinders propulsion. The cross-section of the rotating body preferably has a continuous shape.

[0032] In a preferred embodiment of the present invention, at least one cross-section of a rotating body comprising a propeller and a portion of the medium separated from the rest of the medium by the rotation of the propeller and rotating with the propeller, preferably all cross-sections, and the aspect ratio of the cross-section associated with the axis of rotation of the rotating body is 2 or more, more preferably 3 or more, more preferably 5 or more, more preferably 10 or more, more preferably 20 or more, more preferably 50 or more, more preferably 100 or more. This embodiment of the present invention effectively utilizes the inventors' discovery that strong propulsion is achieved by the high aspect ratio of a rotating body comprising one or more propellers and a co-rotating portion of the medium, even though co-rotation hinders propulsion. The cross-section of the rotating body preferably has a continuous shape. In a preferred embodiment of the present invention, at least one cross-section of a rotating body comprising a propeller and a portion of the medium separated from the rest of the medium by the rotation of the propeller and rotating with the propeller, preferably all cross-sections, and the aspect ratio of the cross-section associated with the axis of rotation of the rotating body is 2 or more, more preferably 3 or more, more preferably 5 or more, more preferably 10 or more, more preferably 20 or more, more preferably 50 or more, more preferably 100 or more. This embodiment of the present invention effectively utilizes the inventors' discovery that strong propulsion is achieved by the high aspect ratio of a rotating body comprising one or more propellers and a co-rotating portion of the medium, even though co-rotation hinders propulsion. The cross-section of the rotating body preferably has a continuous shape. In a preferred embodiment of the present invention, at least one cross-section of a rotating body comprising a propeller and a portion of the medium separated from the rest of the medium by the rotation of the propeller and rotating with the propeller, preferably all cross-sections, and the aspect ratio of the cross-section associated with the axis of rotation of the rotating body is 2 or more, more preferably 3 or more, more preferably 5 or more, more preferably 10 or more, more preferably 20 or more, more preferably 50 or more, more preferably 100 or more. This embodiment of the present invention effectively utilizes the inventors' discovery that strong propulsion is achieved by the high aspect ratio of a rotating body comprising one or more propellers and a co-rotating portion of the medium, even though co-rotation hinders propulsion. The cross-section of the rotating body preferably has a continuous shape. In a preferred embodiment of the present invention, at least one cross-section of a rotating body comprising a propeller and a portion of the medium separated from the rest of the medium by the rotation of the propeller and rotating with the propeller, preferably all cross-sections, and the aspect ratio of the cross-section associated with the axis of rotation of the rotating body is 2 or more, more preferably 3 or more, more preferably 5 or more, more preferably 10 or more, more preferably 20 or more, more preferably 50 or more, more preferably 100 or more. This embodiment of the present invention effectively utilizes the inventors' discovery that strong propulsion is achieved by the high aspect ratio of a rotating body comprising one or more propellers and a co-rotating portion of the medium, even though co-rotation hinders propulsion. The cross-section of the rotating body preferably has a continuous shape. In a preferred embodiment of the present invention, at least one cross-section of a rotating body comprising a propeller and a portion of the medium separated from the rest of the medium by the rotation of the propeller and rotating with the propeller, preferably all cross-sections, and the aspect ratio of the cross-section associated with the axis of rotation of the rotating body is 2 or more, more preferably 3 or more, more preferably 5 or more, more preferably 10 or more, more preferably 20 or more, more preferably 50 or more, more preferably 100 or more. This embodiment of the present invention effectively utilizes the inventors' discovery that strong propulsion is achieved by the high aspect ratio of a rotating body comprising one or more propellers and a co-rotating portion of the medium, even though co-rotation hinders propulsion. The cross-section of the rotating body preferably has a continuous shape. In this embodiment of the present invention, despite the fact that co-rotation hinders propulsion, strong propulsion is achieved by the high aspect ratio of a rotating body comprising one or more propellers and a co-rotating portion of the medium, effectively utilizing the inventors' discovery. The cross-section of the rotating body preferably has a continuous shape. In this embodiment of the present invention, despite the fact that co-rotation hinders propulsion, strong propulsion is achieved by the high aspect ratio of a rotating body comprising one or more propellers and a co-rotating portion of the medium, effectively utilizing the inventors' discovery. The cross-section of the rotating body preferably has a continuous shape. In this embodiment of the present invention, despite the fact that co-rotation hinders propulsion, strong propulsion is achieved by the high aspect ratio of a rotating body comprising one or more propellers and a co-rotating portion of the medium, effectively utilizing the inventors' discovery. The cross-section of the rotating body preferably has a continuous shape. In this embodiment of the present invention, despite the fact that co-rotation hinders propulsion, strong propulsion is achieved by the high aspect ratio of a rotating body comprising one or more propellers and a co-rotating portion of the medium, effectively utilizing the inventors' discovery. The cross-section of the rotating body preferably has a continuous shape.

[0033] A preferred propeller is chiral. More preferably, the propeller is helical or a modified helix. This embodiment of the present invention is based on the inventors' discovery that chirality, particularly a helical shape or a modified helical shape, is particularly effective in achieving propulsion. A preferred propeller is chiral. More preferably, the propeller is helical or a modified helix. This embodiment of the present invention is based on the inventors' discovery that chirality, particularly a helical shape or a modified helical shape, is particularly effective in achieving propulsion. A preferred propeller is chiral. More preferably, the propeller is helical or a modified helix. This embodiment of the present invention is based on the inventors' discovery that chirality, particularly a helical shape or a modified helical shape, is particularly effective in achieving propulsion. Furthermore, it has been found that helical shapes and modified helical shapes are easy to manufacture. Preferably, the helical axis is straight. If the propeller is helical or a modified helix, A preferred propeller is chiral. More preferably, the propeller is helical or a modified helix. This embodiment of the present invention is based on the inventors' discovery that chirality, particularly a helical shape or a modified helical shape, is particularly effective in achieving propulsion. The rotating shaft preferably coincides with a helical shaft. A preferred helical propeller or a modified helical propeller has a constant pitch.

[0034] The preferred propeller has a forward taper at at least one end, more preferably at both ends. In the context of the present invention, the term "forward taper" means that the propeller gradually becomes smaller or thinner towards the end of the propeller. Preferably, the front end of the propeller has a forward taper. In the context of the present invention, "front end" is the tip side of the propeller with respect to the direction of movement. An achievable advantage of this embodiment of the present invention is that at the front end of the propeller, the taper reduces the contact area with the medium. In particular, if the medium has viscoelastic properties, at the front end of the propeller, the pressure exerted by the propeller on the medium becomes greater

[0035] than the tensile strength of the medium. In one embodiment, the tapered tip is located on the rotation axis and / or the helical axis of the propeller when the propeller is helical. In other embodiments, when the propeller is helical, the tip is eccentric, i.e., located away from the rotation axis and / or away from the helical axis. Particularly preferably, the tip is located near the outer periphery with respect to the rotation axis or the helical axis of the propeller. This embodiment effectively utilizes the fact that many media have thixotropic properties and a large shear rate promotes the forward propulsion of the propeller. Since

[0036] the speed at the outer periphery of the propeller is maximum, the tip arranged there can achieve the is 5 mm or less, more preferably 3 mm or less, still more preferably 1 mm or less, even more preferably 500 μm or less, still more preferably 300 μm or less, even more preferably 100 μ m or less, still more preferably 50 μm or less, even more preferably 30 μm or less.

[0037] The minimum radius of any cross-section of the propeller perpendicular to the rotation axis or spiral axis of the propeller is 300 μ m or less, more preferably 100 μm or less, still more preferably 50 μm or less, even more preferably 30 μm or less, still more preferably 10 μm or less, even more preferably 5 μm or less, still more preferably 3 μm or less.

[0038] The length of the propeller divided by the maximum radius of any cross-section of the propeller perpendicular to the rotation axis or spiral axis of the propeller is preferably 0.5 or more, more preferably 1 or more, still more preferably 3 or more, still more preferably 5 or more.

[0039] Preferably, the propeller is unconnected. In the context of the present invention, the term "unconnected (unte thered)" means that no material connection (e.g., a material connection in the form of a wire, tube, or rod is made to the space outside the medium that at least partially, preferably completely, surrounds the propeller. Alternatively, the propeller may be connected to the extent that it is minimally connected. In this case, the driving torque for the propeller is applied wirelessly, and the propeller is connected to a passive element that pulls, for example, the other end of a tube and / or wire whose one end is located outside the medium to a specific position within the medium. A connecting material may be used to effect material transfer, signal measurement ​​​​It is passive and does not provide any active driving force or torque to the propeller. In principle, the propeller may be of the articulated type, in which case, for example, the driving torque of the propeller may be is input by a string, wire, or rod, the rotation of which causes the movement of the propeller together with the connecting member. It is designed to bring about

[0040] The rotation of the propeller is preferably induced remotely. The term "effected remotely" means that the rotation of the propeller can be controlled in any direction. This means that the impact is triggered at a distance of at least five times the maximum diameter of the propeller. In a preferred embodiment of the invention, the rotation of the propeller is remotely induced by a magnetic field. Therefore, the magnetic field source must be at least five times its maximum diameter away from the propeller in any direction. The magnetic field source acts as an actuator to induce the rotation of the propeller. Preferably, the magnetic field source at least partially, and preferably completely, envelops the propeller. Located outside the enclosing medium.

[0041] The magnetic field preferably rotates, thereby inducing the rotation of the propeller. The magnetic moment tends to align with the external magnetic field, causing the propeller to move along the axis of least resistance. As it rotates along the axis of the propeller, the orientation of the propeller is determined by the rotating external magnetic field. , for example, by a set of electrical coils, e.g., Helmholtz coils, or by a permanent magnet. It is possible.

[0042] Preferably, if the magnetic field applies a magnetic gradient force to the propeller in the direction of movement, The force becomes too weak to cause the propeller to move by itself. In this case, the magnetic field has no gradient component in the direction of movement. The preferred magnetic field is 1 G (Gauss). More preferably, the force is greater than 10G, and even more preferably, the force is greater than 50G. The preferred magnetic field is less than 10,000 G, and more preferably less than 1,000 G. , and more preferably less than 500G, for example 100G.

[0043] Preferably, the propeller is at least partially magnetic, so that the rotation is induced by a magnetic field. The components that are magnetically coupled to the propeller or that are materially connected to the propeller are at least partially magnetic. The magnetization is preferably permanent. For this purpose, the propeller is magnetized For example, the propellers are made of magnetized or magnetizable materials. It may be made of magnetized or magnetizable material or may be made of magnetized or magnetizable material. or may be coated with a magnetized or magnetizable material. Examples of suitable materials are Fe, Co, Ni, or magnetic alloys, preferably those mentioned above. The preferred magnetizable materials for the propeller include magnetic alloys that contain some or all of the metals. The material is magnetized in the direction of its maximum length in cross section.

[0044] Additionally or alternatively, the actuator is preferably at least partially similar to a propeller. Or it is completely surrounded by the medium and materially connected to the propeller. The actuator may be an electric motor or a molecular motor, and the material connection The actuator may include a drive shaft. A battery, for example an electrical battery, may likewise be at least partially, preferably completely, medium Surrounded by, and preferably, in this case, an energy source, such as electricity or chemicals stored in an energy reservoir, is provided to the actuator by a material connection, such as , a wire or tube may be provided between the reservoir and the actuator. Additionally or alternatively, the actuator may preferably comprise an energy reservoir that receives energy in a non-connected manner from an energy transmitter located in a space outside the medium. That is, in this case, there will be no material connection between the energy transmitter and the energy receiver. Preferably, the torque applied to the propeller when inducing the rotation of one or more propellers is less than 100 mN·mm (millinewton·millimeter), preferably less than 50 mN·mm, 10 mN·mm, 5 mN·mm, 1 mN·mm. Preferably, the propeller is operated at a speed less than 0.9 times its step-out frequency, more preferably less than 0.8 times , more preferably less than 0.7 times, more preferably less than 0.5 times. Preferably, the propeller is operated at a speed greater than 0.05 times its step-out frequency, more preferably greater than 0.1

[0045] times, more preferably greater than 0.2 times, more preferably greater than 0.3 times. In the context of the present invention, the "step-out frequency" is the frequency at which a torque is produced that is not large enough to exceed the traction force of the medium. The step-out frequency is measured, for example, by driving the propeller by a rotating magnetic field. If the magnetic field rotates slowly enough, the propeller rotates in synchronization with the magnetic field. However, when the magnetic field rotation frequency exceeds a certain value, the applied torque will cause the propeller to lose synchronization with the magnetic field and step out of the rotation.

[0046] Preferably, the propeller is operated at a speed less than 0.9 times its step-out frequency, more preferably less than 0.8 times , more preferably less than 0.7 times, more preferably less than 0.5 times. Preferably, the propeller is operated at a speed greater than 0.05 times its step-out frequency, more preferably greater than 0.1 times, more preferably greater than 0.2 times, more preferably greater than 0.3 times. In the context of the present invention, the "step-out frequency" is the frequency at which a torque is produced that is not large enough to exceed the traction force of the medium. The step-out frequency is measured, for example, by driving the propeller by a rotating magnetic field. If the magnetic field rotates slowly enough, the propeller rotates in synchronization with the magnetic field. However, when the magnetic field rotation frequency exceeds a certain value, the applied torque will cause the propeller to lose synchronization with the magnetic field and step out of the rotation. The step-out frequency is the frequency at which a torque is produced that is not large enough to exceed the traction force of the medium. The step-out frequency is measured, for example, by driving the propeller by a rotating magnetic field. If the magnetic field rotates slowly enough, the propeller rotates in synchronization with the magnetic field. However, when the magnetic field rotation frequency exceeds a certain value, the applied torque will cause the propeller to lose synchronization with the magnetic field and step out of the rotation. If the magnetic field rotates too slowly, the propeller rotates in synchronization with the magnetic field. But when the magnetic field rotation frequency exceeds a certain value, the applied torque will cause the propeller to lose synchronization with the magnetic field and step out of the rotation. The applied magnetic torque does not act strongly enough to synchronize and hold the propeller in the magnetic field. This results in the critical magnetic field rotation frequency being the detuning frequency.

[0047] In a preferred embodiment according to the present invention, the propeller is completely surrounded by a medium. According to this embodiment of the present invention, particularly powerful propulsion is achieved when the entire propeller is in permanent contact with the medium.

[0048] A preferred medium is a viscoelastic body. In the context of the present invention, the term "viscoelastic" means a medium that exhibits both viscous and elastic properties when deformed. Particularly preferred media are viscoelastic fluids in which the viscous properties are dominant over the elastic properties at the applied shear frequency (or shear stress), such as synovial fluid, vitreous humor, mucus. Other particularly preferred media are viscoelastic solids in which the elastic properties are dominant over the viscous properties at the applied shear frequency (or shear stress), such as connective tissue, brain tissue, Matrigel (registered trademark).

[0049] A preferred medium is biological tissue. Particularly preferred biological tissues are brain tissue, kidney tissue, prostate tissue, bladder tissue, vascular tissue, liver tissue, pancreatic tissue, thoracic tissue, lung tissue, skin tissue, adipose tissue, connective tissue, vitreous humor, mucus, or tumor tissue.

[0050] Preferably, the rotation of the propeller induces strain in the medium, and this strain changes the elastic energy of the medium, thereby causing the translational movement of the propeller.

[0051] In a preferred embodiment of the present invention, a load moving relative to the medium by the propeller is ​​It is attached to the propeller. Examples of preferred loads include molecules, nanoparticles, porous polymer substrates , porous silicon, and / or one or more electrical circuits attached to the propeller Advantageously, one or more electronic circuits are adapted to control the movement of the propeller Alternatively or additionally, one or more tubes and / or wires pulled from the outside to the inside of the medium may be attached to the propeller .

[0052] The trajectory of movement is preferably remotely controlled, for example, by changing the direction and / or rotational frequency of a magnetic field, or by changing the direction, rotational axis, rotational direction and / or rotational frequency of an actuator at least partially surrounded by the medium . Also, a number of propellers according to the invention may be combined in one device, and in such a case, the propulsion direction of the device may be controlled by individually varying the rotational frequencies of these propellers . Preferably, a control device, for example, a suitably equipped and programmed PC, may be connected to the actuator to control the trajectory of movement (in this case, for example, a magnetic field source or actuator is at least partially surrounded by the medium) . . . . .

[0053] The trajectory of movement is preferably imaged and / or measured by one or more of the following imaging methods, namely, optical microscopy, fluorescence imaging, X-ray imaging, computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), infrared imaging, and ultrasonic imaging . . .

[0054] The propeller is made of, for example, one or more kinds of metals, such as copper, gold, cobalt, nickel Iron, steel, titanium, one or more polymers, e.g., Teflon®, PLA, PMMA, PC, and / or one or more semiconductors, e.g., silicon, or a combination of such materials. In a particularly preferred embodiment of the present invention, the propeller may be made of a biocompatible material. An achievable advantage of this embodiment of the present invention is that it does not need to be retrieved after deployment within the tissue. This is because the propeller decomposes and is absorbed into the body. The propeller may, for example, be composed of two or more regions, specifically, one rigid region may be provided

[0055] for propulsion and one biocompatible region may be provided for drug delivery and drug release. Examples of suitable methods for manufacturing the propeller include molding, in particular injection molding, electrodeposition, direct drawing, 3D printing, and machining. A preferred manufacturing method is (1) a step of defining a straight helical axis, and (2) a step of preparing a plate extending along the helical axis, wherein the aspect ratio of at least one cross-section, preferably all cross-sections, of the plate associated with the helical axis is 2 or more, and (3) a step of applying torque to the plate along the helical axis

[0056] to thereby twist the plate into a helical shape. In the next step, the helix is a step of...; (2) casting the first structure into the second material, removing the first structure from the second material, and generating a female mold replica of the first structure; (3) injecting a molding material into the female mold, curing the molding material under predetermined physical and chemical conditions, and forming a second solid structure; and (4) detaching the second solid structure from the female mold, thereby obtaining a predetermined propeller. The molding material is a mixture of at least two component materials. Examples of preferred component materials include polymer materials, magnetic materials, drug molecules, and radioactive materials. Accordingly, the molding material may be composed of, for example, a polymer material and a magnetic material. The curing conditions preferably include at least one of temperature, pH, magnetic field, electric field, sound field, light field, and radiation. For example, the mixture is an epoxy resin mixed with ferromagnetic particles, and the polymer is cured at room temperature in a direction perpendicular to the helical axis in a magnetic field. In step (3) above, a drug may be incorporated, or in step (4) above, the drug may be absorbed by the propeller material after detachment. By this method, the structuring, magnetization, and functionalization of the propeller can be achieved in a single process. Hereinafter, the present invention will be described in more detail based on schematic diagrams. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1(a) is a perspective view of an embodiment of a propeller according to the present invention. FIG. 1(b) is a cross-sectional view of the propeller of FIG. 1(a).

[0057]

[0058]

[0059]

[0060]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

DETAILED DESCRIPTION OF THE INVENTION

[0061] [Propeller Moving within the Tissue Model] An achievable advantage of Propeller 1 according to the present invention is that Propeller 1 can efficiently self-propel within a viscoelastic medium, such as a biological tissue. FIG. 2 shows Propeller 1 according to the present invention fully immersed in a gel medium of Matrigel (registered trademark), a hydrogel used as a tissue model for verifying the propeller. Gibco (registered trademark) or Matrigel commercially available from Life Technologies (registered trademark) is a trade name for a gelatin protein mixture secreted from mouse sarcoma cells. Matrigel is similar to the complex extracellular matrix (EMC) found in many tissues and is widely accepted as an in vitro model for cell 3D culture, tumor cell metastasis research, and cancer drug screening. Here, Matrigel will serve as the gel medium 2 of the connective tissue through which Propeller 1 passes. The Matrigel solution was received in an ice-cold state and gelled by being held in a 37 °C incubator for one hour. Propeller 1 was inserted into the gel medium 2 with tweezers. A uniform magnetic field (adjustable within the range of 50 to 1000 gauss) and a continuous rotational direction (frequency within the range of 1 to 100 Hz) were applied, and the magnetic field was rotated at a speed of 10 Hz. A circle was formed at one end of Propeller 1.

[0062] ​​​​​The cylindrical magnet 3 is mounted so as to withstand torque. The cylindrical magnet 3 is made of a neodymium, iron, and boron (NdFeB) material, has a diameter of 200 μm and a length of 400 μm, and is magnetized in the diameter direction. This magnet has a permanent magnetic moment and is adapted to rotate with an external rotating magnetic field. The propeller, due to its special shape design, converts rotation into translation (forward or backward propulsion), resulting in a net displacement within the gel medium 2 or biological tissue.

[0063] As best shown in FIG. 1(a), the propeller 1 has a chiral shape, more precisely, a helical shape. This propeller 1 is left-handed, but of course, a right-handed one is equally suitable. In the propeller of FIG. 1, the rotation axis 4 and the helical axis coincide. The moving direction v is indicated by the rightward arrow v. The rotation direction is indicated by the semi-circular arrow ω. As shown in the cross-sectional view of FIG. 1( b), the aspect ratio of any cross-section 5 of the propeller 1 orthogonal to the helical axis is significantly larger than 5. The aspect ratio is obtained by dividing the maximum radius 6 of the cross-section 5 by the minimum semi- radius 7 of the cross-section 5. The radii 6, 7 are the distances from the point 8 where the rotation axis 4 perpendicularly penetrates the cross-section 6 to the point on the periphery 9 of the cross-section.

[0064] From the image of FIG. 3, it can be seen how the propeller 1 propagates within the gel medium 2 of Matrigel. The lower image is the image 18 seconds after the upper image. The dotted line indicates the initial position of the magnet 3. At a rotational frequency of 10 Hz, a speed of approximately 45 μm / s along the helical axis of the propeller was observed. By selecting the rotation direction clockwise or counterclockwise, the propeller 1 can move either forward or backward. ​

[0065] In FIGS. 4(a) to 4(d), the cross-sectional shape of the propeller 1 according to the present invention is schematically compared with the cross-sectional shapes of the propellers known from the following non-patent literature (Non-Patent Document 2 (L Zhang, J J Abbott, L X Dong, B E Kratochvil, D Bell, and B J Nelson): FIG. 4(b), Non-Patent Document 1 (A Ghosh and P Fischer): FIG. 4(c), and Non-Pat ent Document 4 (T Qiu, J Gibbs, D Schamel, A Mark, U Choudhury, and P Fischer): FIG. 4 (d)). Three-dimensional figures are shown in the upper part, and cross-sectional shapes are shown in the lower part. The cross-section 5 of the propeller of the present invention has a significantly larger aspect ratio than the cross-section 5' based on the radii 6', 7' of the propeller 1' according to the prior art. It will be understood that the ratio is significantly larger. Furthermore, when the propeller 1 rotates in the viscoelastic medium 2 and moves through the viscoelastic medium 2,

[0066] a portion 10 of the medium 2 adheres to the surface of the propeller 1 and rotates with the propeller 1. This is schematically shown in FIG. 5. In the example of FIG. 5, the aspect ratio of the cross-section of the rotating body including the propeller 1 and the portion 10 of the medium 2 that rotates with the propeller 1 is also greater than 3. In this case, the aspect ratio is obtained by dividing the maximum radius 11 of the cross-section of the rotating body by the minimum radius 12 of the cross-section of the rotating body. The radii 11, 12 are the distances from the point 8 where the rotation axis 4 perpendicularly penetrates the cross-section to the points on the periphery 9 of the cross-section of the rotating body.

[0067] [Propulsion mechanism of the propeller] The inventor has found that, without affecting other rights, the propeller 1 according to the present invention is a viscoelastic medium When used in the body, it is considered to effectively utilize a novel propulsion mechanism different from the propulsion mechanism in the viscous fluid as described in the prior art. Figures 6(a) and 6(b ) show the results of an experiment by particle image velocimetry (PIV). In this experiment, to show the movement, particularly the deformation, of the gel medium 2, fluorescent polystyrene beads with a diameter of 15 μm (Fl uoSpheres (registered trademark), Life Technologies) were used as tracer particles and mixed in the gel medium 2 of Matrigel . A beam of a green laser having a wavelength of 532 nm was expanded into a laser sheet by a cylindrical lens and then guided onto a thin sheet of the gel medium 2 of Matrigel . The movement of the propeller 1 and the tracer particles was recorded by a microscope and a video camera equipped with a long-pass filter (OD4 - 550 nm, Edmund Optics ). The positions of the tracer particles were analyzed by a special specification script in Matlab (R2014b, Mathworks) and plotted as circles in each frame of the video. These circles are shown in Figure 6(a) and enlarged in Figure 6(b ). The trajectory of one tracer particle 13 is shown in Figure 6(b). The particle 3 follows a closed, essentially elliptical orbit 14 over multiple rotations of the propeller 1 . The normalized deformation can be calculated from the ratio of the radial displacement d to the distance r from the axis of rotation . . . . . . .

[0068] This experiment suggests that the movement (deformation) of the viscoelastic medium 2 is clearly different from the flow around the propeller in the viscous fluid. In the fluid, the particles rotate with the propeller when the propeller makes a full rotation and move in two mutually orthogonal directions at low Reynolds numbers . . A forward thrust is generated by the difference in hydrodynamic traction. This is explained by the aforementioned literature. However, in the case of the propeller 1 disclosed herein, different particle trajectories of motion have been found. This suggests that the novel design of the propeller 1 enables a novel propulsion mechanism in a viscoelastic medium that has not been reported heretofore.

[0069] The relaxation time of viscoelastic solids, including most biological tissues, is often on the order of minutes, but the propeller typically rotates at a frequency of 1 - 10 Hz. Therefore, the cycle time (0.1 - 1 s) of the rotation of the propeller 1 is significantly shorter than this relaxation time, so only the elastic response of the gel needs to be considered. For example, as shown in FIG. 7, the cross - section 5 of the propeller 1 is modeled as a rectangular solid that rotates within the initial rectangular hole 15 of the medium 2. Note in FIG. 7(b) that when the propeller 1 rotates, the medium 2 deforms without flowing. A large deformation (strain) of the medium 2 is caused by the rotation of the propeller 1. The effective deformation of the medium 2 around the propeller 1 is much larger than that in the prior - art propeller designs (the propeller 1' in FIG. 8 where the corresponding elements are in the form of a screw reported in the prior art and the propeller 1' in FIG. 9 where the corresponding elements are in the form of a conventional screw, which are exemplarily shown). In the medium 2' (where the gap 15' and the hatched effective deformation region are shown). The medium 2 is considered an elastic body, that is, a spring where the reaction force is actively related to the deformation. Therefore, a large deformation of the medium 2 requires a larger rotational torque and results in a large forward thrust. These two phenomena have been observed in experiments.

[0070] For further explanation, a force diagram of a small area of the propeller 1 (which rotates counterclockwise and has its leading edge move upward to move rightward) is shown in FIG. 10. The direction of rotation is indicated by the upward arrow v. From this force diagram, it is clear that there is a propulsive force component Fp directed rightward. Similar to the situation shown in FIG. 7, the greater the deformation, the greater the forward propulsive force. Therefore, the proposed propulsion mechanism of the propeller 1 according to the present invention can be summarized in the following three aspects. First, the rotation of the propeller 1 causes a large deformation of the gel medium 2. More specifically, the large aspect ratio of the cross-section 5 of the propeller 1 induces a large deformation of the gel medium 2, which will result in a large forward propulsive force Fp. Second, the pressure of the tip 16 of the propeller 1 should be higher than the tensile strength of the gel medium 2 to break the gel medium 2. The area of the tip 16 of the propeller 1 is preferably as small as possible. For example, a sharp tip 16 is preferred. Further, the new cutting region (crack) 15 of the medium 2 due to the forward movement of the tip 16 of the propeller also has a high aspect ratio, such as a rectangular shape, as shown by the white region in FIG. 7(a). This also results in a large deformation when the propeller 1 rotates. This is different from the design of the conventional propeller 1'. In the design of the conventional propeller 1', as shown in FIG. 9(a), the crack 15' is almost circular, and the deformation of the medium 2' induced by the conventional propeller 1' is small. Third, as shown in FIG. 5, after the effective adhesion of the medium 2 around the propeller 1, the above two conditions are satisfied. This criterion ensures the continuous movement of the propeller 1 within the tissue. (The propeller that rotates upward at the leading edge to move rightward) is shown in FIG. 10. The direction of rotation is indicated by the upward arrow v. From this force diagram, it is clear that there is a propulsive force component Fp directed rightward. Similar to the situation shown in FIG. 7, the greater the deformation, the greater the forward propulsive force. Therefore, the proposed propulsion mechanism of the propeller 1 according to the present invention can be summarized in the following three aspects. First, the rotation of the propeller 1 causes a large deformation of the gel medium 2. More specifically, the large aspect ratio of the cross-section 5 of the propeller 1 induces a large deformation of the gel medium 2, which will result in a large forward propulsive force Fp. Second, the pressure of the tip 16 of the propeller 1 should be higher than the tensile strength of the gel medium 2 to break the gel medium 2. The area of the tip 16 of the propeller 1 is preferably as small as possible. For example, a sharp tip 16 is preferred. Further, the new cutting region (crack) 15 of the medium 2 due to the forward movement of the tip 16 of the propeller also has a high aspect ratio, such as a rectangular shape, as shown by the white region in FIG. 7(a). This also results in a large deformation when the propeller 1 rotates. This is different from the design of the conventional propeller 1'. In the design of the conventional propeller 1', as shown in FIG. 9(a), the crack 15' is almost circular, and the deformation of the medium 2' induced by the conventional propeller 1' is small. Third, as shown in FIG. 5, after the effective adhesion of the medium 2 around the propeller 1, the above two conditions are satisfied.

[0071] Design of a conventional propeller 1' having a hollow opening in the center, e.g., as shown in FIGS. 4(b) and 4(c ) of the prior art design does not efficiently propel in a viscoelastic medium. The reason is , as follows. That is, during the rotation of the propeller, considering that the opening is filled with the viscoelastic medium and the medium rotates together with the propeller, as shown in FIG. 8(b), the entire structure will not have a high aspect ratio at any cross-section. In other words, the gel filling part changes the conventional propeller shape to a substantially cylindrical shape, inducing extremely limited deformation of the surrounding medium. As a result, the conventional propeller can only rotate at the same position in the viscoelastic medium and cannot achieve a net deformation. The present invention in the preferred embodiment is significantly different from the prior art design at least at one cross-section, preferably at all cross-sections, at the point where the axis penetrates the propeller in a cross-section perpendicular to the helical axis of the propeller. In other words, at least at one cross-section, preferably at all cross-sections, during rotation, the center is inside the propeller. In some specific types of viscoelastic media, such as yield stress fluids, the propeller can break (or liquefy) a part of the medium by the shear stress induced by the rotation of the propeller. Also, the forward propulsion of the propeller can be brought about by the rearward transfer of the broken (liquefied) part of the medium. Preferably, in order to operate the propeller 1, a rotational speed that brings the highest propulsion speed should be used. The value, which depends on both the geometric shape of the propeller 1 and the rheology of the medium, can be determined experimentally by sweeping the frequency and measuring the propulsion speed. In the viscoelastic medium, the conventional propeller can only rotate at the same position and cannot achieve a net deformation. The present invention in the preferred embodiment is significantly different from the prior art design at least at one cross-section, preferably at all cross-sections, at the point where the axis penetrates the propeller in a cross-section perpendicular to the helical axis of the propeller. In other words, at least at one cross-section, preferably at all cross-sections, during rotation, the center is inside the propeller. at least one cross-section, preferably all cross-sections, perpendicular to the helical axis of the propeller, at the point where the axis penetrates the propeller, is clearly different from the prior art design. In other words, at least at one cross-section, preferably at all cross-sections, during rotation, the center is inside the propeller. In some specific types of viscoelastic media, such as yield stress fluids, the propeller can break (or liquefy) a part of the medium by the shear stress induced by the rotation of the propeller. Also, the forward propulsion of the propeller can be brought about by the rearward transfer of the broken (liquefied) part of the medium. Preferably, in order to operate the propeller 1, a rotational speed that brings the highest propulsion speed should be used. The value, which depends on both the geometric shape of the propeller 1 and the rheology of the medium, can be determined experimentally by sweeping the frequency and measuring the propulsion speed. Preferably, in order to operate the propeller 1, a rotational speed that brings the highest propulsion speed should be used. The value, which depends on both the geometric shape of the propeller 1 and the rheology of the medium, can be determined experimentally by sweeping the frequency and measuring the propulsion speed.

[0072] In some specific types of viscoelastic media, such as yield stress fluids, the propeller can break (or liquefy) a part of the medium by the shear stress induced by the rotation of the propeller. Also, the forward propulsion of the propeller can be brought about by the rearward transfer of the broken (liquefied) part of the medium. In some specific types of viscoelastic media, such as yield stress fluids, the propeller can break (or liquefy) a part of the medium by the shear stress induced by the rotation of the propeller. Also, the forward propulsion of the propeller can be brought about by the rearward transfer of the broken (liquefied) part of the medium. In some specific types of viscoelastic media, such as yield stress fluids, the propeller can break (or liquefy) a part of the medium by the shear stress induced by the rotation of the propeller. Also, the forward propulsion of the propeller can be brought about by the rearward transfer of the broken (liquefied) part of the medium. In some specific types of viscoelastic media, such as yield stress fluids, the propeller can break (or liquefy) a part of the medium by the shear stress induced by the rotation of the propeller. Also, the forward propulsion of the propeller can be brought about by the rearward transfer of the broken (liquefied) part of the medium.

[0073] Preferably, in order to operate the propeller 1, a rotational speed that brings the highest propulsion speed should be used. The value, which depends on both the geometric shape of the propeller 1 and the rheology of the medium, can be determined experimentally by sweeping the frequency and measuring the propulsion speed. Preferably, in order to operate the propeller 1, a rotational speed that brings the highest propulsion speed should be used. The value, which depends on both the geometric shape of the propeller 1 and the rheology of the medium, can be determined experimentally by sweeping the frequency and measuring the propulsion speed. Preferably, in order to operate the propeller 1, a rotational speed that brings the highest propulsion speed should be used. The value, which depends on both the geometric shape of the propeller 1 and the rheology of the medium, can be determined experimentally by sweeping the frequency and measuring the propulsion speed. It is possible. The optimal frequency in the viscoelastic medium 2 of the propeller 1 disclosed herein can be made significantly lower than the detuning frequency. It has been found that as the frequency increases beyond the optimal value, the propeller 1 continues to rotate, but the propulsion speed decreases dramatically until it reaches zero. Conversely, in a viscous fluid with a low Reynolds number, the optimal frequency of the propeller 1 is very close to the detuning frequency, and the propulsion speed increases in proportion to the driving frequency until detuning occurs. This observation also suggests that the propeller 1 of the present invention enables a novel propulsion mechanism in a viscoelastic medium.

[0074] [Propeller Moving Inside Brain Sample] The optical micrograph of FIG. 11 shows the propeller according to the present invention passing through porcine brain tissue to demonstrate the ability to move inside actual biological soft tissue. Fresh porcine brains stored in an ice-cold state were received from a local abattoir. A portion of the brain approximately 25×25×8 mm3 was excised, and the propeller 1 was inserted by forceps. Since this brain tissue was relatively thin, the movement of the propeller within the brain tissue was observed by using white light backlighting. The dashed line indicates the initial position of the propeller 1. An average propulsion speed of approximately 35 μm was measured at a rotational frequency of about 1 Hz. Due to the shape of the propeller 1, the rotation of the propeller 1 could be actuated by a limited magnetic torque. In the experiment, a magnetic field of 100 - 300 G was sufficient to drive the propeller 1 through the brain tissue sample. This magnetic field can be applied by a conventional magnetic field generator, for example, an electric coil or a permanent magnet mechanism to be discussed in more detail below.

[0075] [Manufacture of Propeller] The method for manufacturing the propeller 1 according to the present invention is shown in FIG. 12. By machining approach, the propeller 1 was made from copper. A copper wire having a diameter of 50 μm was mechanically rolled to obtain a flat plate 18 having a width of 255 μm and a thickness of 13 μm. As shown in FIG. 12 The plate 17 was attached between two concentric clamps 18, 19 that can be rotated relative to each other. One of the clamps 19 was stationary and the other clamp 18 was rotated to twist the plate 17 to obtain a chiral structure. While twisting, a normal force is generated in the axial direction v, so the distance between the two clamps 18, 19 was adjusted accordingly. During this pro cess, sensors may be used to measure the force and torque. The distance and angular position of the clamps may be controlled by a computerized motor. In this way, the pitch dimensions and chirality of the propeller can be controlled. Subsequently, the twisted long plate 17 was cut into individual propellers 1 having a desired length of 2 mm. Finally, a small magnet having a diameter of 200 μm and a length of 400 μm was attached to one tip of the propeller 1.

[0076] The cutting procedure can be performed by machining, laser cutting, (focused) ion etching, or chemical etching ing. The mask for etching can be provided on both sides of the plate by photolithography before the twisting process. In this way, a mass production process for the propeller is achieved.

[0077] Another method for manufacturing the propeller 1 according to the present invention is shown in FIG. 13. The structure of the propeller 1 is initially obtained from, for example, a copper material by the method described above or by 3D printing (FIG. 1 ​​​3(a). Next, this structure is cast into a second material, such as a soft polymer like PDMS (Fig. 13(b)). The first structure is removed from the female mold 20, for example, by rotating the propeller 1 in the right direction and sending the propeller 1 out of the female mold 20, or by expanding the soft polymer female mold 20. A liquid polymer material or mixture, such as a mixture of an epoxy resin and ferromagnetic particles (with an average diameter of 40 μm) is injected into the female mold 20 (Fig. 13(d)), and the polymer is cured at room temperature in the presence of an external magnetic field as indicated by the arrow in Fig. 13(d). Finally, the propeller 1 is obtained by destroying the female mold 20 or by rotating the propeller 1 in the right direction (Fig. 13(e)). The propeller 1 has a rightward magnetic moment M (as shown in Fig. 13(f)). This is because when an external magnetic field B is applied, the magnetic particles in the structure align in the right direction . In the above molding steps, it may be incorporated into the drug-polymer mixture or absorbed by the propeller material after detachment in the last step. . The propeller 1 has a rightward magnetic moment M (as shown in Fig. 13(f)). This is because when an external magnetic field B is applied, the magnetic particles in the structure align in the right direction . . In the above molding steps, it may be incorporated into the drug-polymer mixture or absorbed by the propeller material after detachment in the last step. .

[0078] Fig. 14 shows how the two tips 16 of the propeller 1 are shaped, preferably into sharp tips, by cutting, etching, or molding. In this way, by reducing the contact area of the tip 16, the pressure on the tip 16 can be increased , or the shear rate of the medium 2 in front of the propeller can be increased. Since many biological media tend to shear thinning, a large shear rate promotes the forward propulsion of the propeller . In this case, the sharp tip of the propeller is preferably the edge of the propeller tip 16 and is located far from the axis of rotation. . . . .

[0079] "Operation of the Propeller" A suitable mechanism for inducing rotation in the propeller by a rotating magnetic field is known, for example, from the aforementioned non-patent document 4 (T Qiu, J Gibbs, D Schamel, A Mark, U Choudhury, and P Fischer). The relevant part of this document is hereby incorporated by reference and made part of what is included here.

[0080] The magnetic field may be spatially homogeneous or may have a magnetic gradient within the space. However, preferably, the tensile force acting on the propeller caused by the magnetic gradient is generated in the same direction as the direction of the self-propulsion force of the propeller 1. The magnetic field can be generated by an electric coil. For example, three pairs of Helmholtz coils can control the movement of the propeller in three-dimensional space by changing the phase and amplitude of the current in different coils. Also, the magnetic field can be generated by one or more permanent magnets, for example, several permanent magnets specially arranged in the space or only one magnet separated from the propeller by the required distance. In order to control the propulsion trajectory by a permanent magnet mechanism, the rotation axis of the mechanism will be changed.

[0081] To implement the present invention in various embodiments, the features disclosed in the description, claims, and drawings of this embodiment may be associated individually or in any combination. ​​​​​​​​​​​​

Claims

1. a medium (2) surrounding the propeller (1) at least partially; A method for moving a medium (2), comprising the steps of: an actuator moving the propeller (1) relative to the medium (2); ) to induce rotation of the propeller (1) about the axis of rotation (4) of the propeller (1) a method for converting said rotational motion into a movement of said propeller (1) relative to said medium (2) At least one cross section (5) of the propeller (1), The aspect ratio of the cross section (5) associated with the axis of rotation of the method.

2. a medium (2) surrounding the propeller (1) at least partially; A method for moving a medium (2), comprising the steps of: an actuator moving the propeller (1) relative to the medium (2); ) to induce rotation of the propeller (1) about the axis of rotation (4) of the propeller (1) In a method of converting the rotational motion of the rotor (1) into a movement of the propeller (1) relative to the medium (2), The propeller (1) and the rotation of the propeller (1) causes the medium (2) to be removed from the remainder of the medium (2). and a portion (10) of the medium (2) that is separated from the propeller (1) and rotates together with the propeller (1). At least one cross section (5) of a rotating body including a rotor, the cross section (5) being associated with the axis of rotation of the rotating body. The method according to claim 1, characterized in that the aspect ratio of the cross section (5) is 3 or more.

3. The propeller (1) is chiral or generalized chiral, 2. The method according to claim 1 .

4. The propeller (1) is a spiral or modified spiral propeller.

2. The method according to claim 1 .

5. According to any of the preceding claims, the front end of the propeller is provided with a forward taper. The method according to any one of the preceding claims.

6. 10. Any of the preceding claims, characterized in that the propeller (1) is non-articulated. The method according to one aspect.

7. The rotation of the propeller (1) is remotely induced by a magnetic field.

20. A method according to claim 1, wherein

8. The medium (2) is at least one of a viscoelastic fluid, a viscoelastic solid, or a physiological tissue.

2. The method according to claim 1, further comprising:

9. The rotation of the propeller (1) induces a strain in the medium (2), which changes the elastic energy of the medium, causing a translational movement of the propeller (1).

4. The method according to any one of the preceding claims, characterized in that

10. A helical or modified helical propeller (1), comprising at least The rotational movement of the propeller (1) relative to a partially surrounding medium is controlled by the translation of the propeller (1). A helical or modified helical propeller (1) for converting the propeller (1) into a rotating one. ) associated with the helical axis of the propeller (1), A spiral or modified spiral is characterized in that the aspect ratio of the cross section (5) is 3 or more. Spiral propeller.

11. Any cross section (5) of the propeller (1) perpendicular to the rotation axis (4) of the propeller (1) 11. The propeller according to claim 10, characterized in that the maximum radius (6) of １）。

12. Any cross section (5) of the propeller (1) perpendicular to the rotation axis (4) of the propeller (1) 12. The method according to claim 10 or 11, characterized in that the minimum radius (7) of the Propeller (1).

13. determining a straight helical axis; Providing a plate (17) extending along the helical axis, At least one cross section (5) of the shaft (17), said cross section being associated with said helical axis. (5) having an aspect ratio of 3 or more; A torque is applied to the plate (17) along the helical axis, thereby twisting the wire (17) into a helical shape; 1. A method for manufacturing a propeller comprising:

14. Providing a first structure having a desired geometric shape; The first structure is injected into a second material and the first structure is removed from the second material. and generating a female replica of said first structure; A molding material is injected into the female mold, and the molding material is hardened under predetermined physical and chemical conditions. forming a second solid structure; The second solid structure is separated from the female mold, thereby obtaining a desired propeller. Steps and 1. A method for manufacturing a propeller comprising:

15. The molding material is a mixture of at least two component materials. Item 15. The method according to item 14.

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