WO2018183949A1 - Magnetically actuatable probe for tissue penetration - Google Patents

Abstract

A medical apparatus for probing into organic tissue includes a probe having an elongate body extending along a central axis and having a first and second ends and a taper at the first end. An internal channel extends within the probe body between the first and second ends, and a resilient member within the channel is disposed adjacent the second end. The probe further includes a magnetic member disposed within the channel and configured to move between the resilient member and the first end.

Description

MAGNETICALLY ACTUATABLE PROBE FOR TISSUE PENETRATION

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims benefit of U.S. provisional patent application Serial No 62/479,249 filed March 30, 2017, and entitled "Magnetic Hammer for Tissue Penetration," which is hereby incorporated herein by reference in its entirety for all purposes.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] This project includes work sponsored by National Science Foundation grant number 1646566, CPS: Synergy: Collaborative Research: MRI Powered & Guided Tetherless Effectors for Localized Therapeutic Interventions.

BACKGROUND

[0003] Field of the Disclosure

[0004] This disclosure relates generally to surgery within a living body and medical devices used therewith. More particularly, it relates to an apparatus and system for probing into a living body during minimally invasive surgeries.

[0005] Background to the Disclosure

[0006] Many surgeries and surgical interventions (drug delivery, placement of brachy therapy, delivery of stem cells) are needed in places deep within the human body. Traditional surgery requires opening the patient with macro-incisions. Even minimally invasive surgeries need to cut holes, called 'ports' into the patient's tissue. Catheter-based systems pass catheters through the vasculature, including blood vessels, in the body to reach surgery locations, but this commonly requires a long catheter that drags along the vasculature walls and that may cause damage or increase the risk of strokes by dislodging plaques. The extended length limits the amount of force that can be applied at the end of the catheter.

[0007] Other work has presented a way to avoid cutting ports or inserting long catheters by using untethered capsules or probes propelled by an external magnetic field. This arrangement is sometimes called a micro-robot, a mini-scale robot, or a millirobot. The magnetic field can be provided by an MRI scanner and, within limits of the conventional technology, can push the capsule through the blood vessels and vasculature of the body to a certain degree. However, using conventional systems, the MRI scanner cannot provide enough force to push the capsule through tissue, including vessel walls, or through blockages. Conventional MRI scanners also cannot provide enough force to conduct surgeries. Thus, present methods of probing inside the human body during surgery have been successful when it is desirable to cause a capsule to travel through the vasculature of the body, but not when it is necessary or desirable to cause the capsule to travel in other areas within the body where it must pass through tissue or blockages. Examples include the ferrous capsules described in [Vartholomeos, Panagiotis, M. Reza Akhavan- Sharif, and Pierre E. Dupont. "Motion planning for multiple millimeter-scale magnetic capsules in a fluid environment." Robotics and Automation (ICRA), 2012 IEEE International Conference on. IEEE, 2012], and the capsule described in [Martel, Sylvain, et al. "Automatic navigation of an untethered device in the artery of a living animal using a conventional clinical magnetic resonance imaging system." Applied physics letters 90.11 (2007): 114105].

BRIEF SUMMARY OF THE DISCLOSURE

[0008] Disclosed herein are apparatus, systems and methods by which a probe may be magnetically induced during surgical procedures to pass though tissue, including vascular walls and other tissue of a living patient, and/or through vasculature blockages. In some embodiments, a medical apparatus for probing into organic tissue includes a probe having an elongate body extending along a central axis and having a first and second ends and a taper at the first end. An intemal channel extends within the probe body between the first and second ends, and a resilient member within the channel is disposed adjacent the second end. The probe further includes a magnetic member disposed within the channel and configured to move between the resilient member and the first end. In some embodiments, the probe includes an impact surface disposed within the channel at the first end, and the magnetic member is configured to strike periodically the impact surface when a force generated by an alternating magnetic gradient acts on the magnetic member. In some embodiments, a rigid member extends from the impact surface and forms a tapered tip at the first end. The magnetic member is a sphere in some embodiments.

[0009] The medical apparatus may further comprise a magnetic source configured to generate an alternating magnetic gradient, which reverses direction repeatedly, and the alternating magnetic gradient may, in some embodiments, be configured to cause the magnetic member to oscillate between the resilient member and the impact surface that is disposed within the channel at the first end. In some embodiments, the alternating magnetic gradient is configured to cause the magnetic member to oscillate between the resilient member and the impact surface at a resonant frequency. The magnetic source is a magnetic resonance imaging device (MRID) in some embodiments.

[0010] Also disclosed herein is surgical apparatus for probing into organic tissue, comprising: a probe body having a first end and a second end, the first end having a taper; an elongate chamber within the probe body; a resilient member within the chamber and disposed adjacent the second end; an impact surface disposed within the chamber opposite from the resilient member; and a magnetic member disposed within the chamber and configured to move within the chamber between the resilient member and the impact surface. In some embodiments, the magnetic member is configured to strike periodically the impact surface when a force generated by an alternating magnetic gradient acts on the magnetic member. The surgical apparatus may include a knife at the first end, or a tissue sampling device, such as barbs, or a biopsy punch. In some embodiments, the surgical apparatus further includes a magnetic source configured to generate an alternating magnetic gradient, which reverses direction repeatedly, and to cause the magnetic member to oscillate between the resilient member and the impact surface.

[0011] Also disclosed herein is a method for performing surgeries or surgical interventions using a probe driven by a magnetic field, the method including: providing a probe having a magnetic member configured to oscillate within an internal channel of the probe body; and controlling a magnetic gradient to cause the magnetic member to oscillate within the probe body. In some embodiments, the method also includes: monitoring the movement of the magnetic member relative to the probe body; wherein controlling a magnetic gradient includes adjusting the magnetic gradient based on the movement of the magnetic member relative to the probe body. The method may also include taking a tissue sample using the probe. In some embodiments, the method also includes delivering a drug into organic tissue using the probe.

[0012] Thus, embodiments described herein include a combination of features and characteristics intended to address various shortcomings associated with certain prior devices, systems, and methods. The various features and characteristics described above, as well as others, will be readily apparent to those of ordinary skill in the art upon reading the following detailed description, and by referring to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] For a detailed description of the disclosed exemplary embodiments, reference will now be made to the accompanying drawings:

[0014] Figure 1 shows a cross-sectional side view of an embodiment of a probe in accordance with principles described herein;

[0015] Figure 2 shows a schematic view in cross-section of a medical apparatus that includes a magnetic source and the probe of Figure 1 in accordance with principles described herein.

[0016] Figure 3 shows a cross-sectional side view of an embodiment of a probe having a tip in accordance with principles described herein;

[0017] Figure 4 shows a cross-sectional side view of an embodiment of a probe having a tether attached to its posterior end, in accordance with principles described herein;

[0018] Figure 5 shows a cross-sectional side view of an embodiment of a probe having a tip that includes a sharp, hollow biopsy punch for gathering a sample, in accordance with principles described herein;

[0019] Figure 6 shows a cross-sectional side view of an embodiment of a probe having a barbed tip in accordance with principles described herein; and

[0020] Figures 7 A and 7B show a perspective and cross-sectional views, respectively, of an embodiment of a probe having an extendable-retractable knife at the leading end of the probe in accordance with principles described herein, the tip being in a retracted position;

[0021] Figures 8A and 8B show a perspective and cross-sectional views, respectively the probe of Figure 7A with the knife in an extended position;

[0022] Figures 9A and 9B show an embodiment of a probe having position sensors at each end to detect a movable magnetic member in accordance with principles described herein;

[0023] Figure 10 shows an embodiment of a probe having a position sensor at one end to detect a movable magnetic member in accordance with principles described herein;

[0024] Figure 11 shows a perspective view, including schematic elements, of a medical apparatus that includes a probe and a magnetic source coupled with Hall-effect sensors in accordance with principles described herein; and

[0025] Figure 12 is a graph of a magnetic member's cycle period between impacts with an impact surface as a function of reverse force duration for different initial velocities, as is applicable to a probe, such as the probe of Figure 1, in accordance with principles described herein.

NOTATION AND NOMENCLATURE

[0026] The following description is exemplary of certain embodiments of the disclosure. One of ordinary skill in the art will understand that the following description has broad application, and the discussion of any embodiment is meant to be exemplary of that embodiment, and is not intended to suggest in any way that the scope of the disclosure, including the claims, is limited to that embodiment.

[0027] The figures are not necessarily drawn to-scale. Certain features and components disclosed herein may be shown exaggerated in scale or in somewhat schematic form, and some details of conventional elements may not be shown in the interest of clarity and conciseness. In some of the figures, to improve clarity and conciseness, one or more components or aspects of a component may be omitted or may not have reference numerals identifying the features or components. In addition, within the specification, including the drawings, like or identical reference numerals may be used to identify common or similar elements.

[0028] As used herein, including in the claims, the terms "including" and "comprising," as well as derivations of these, are used in an open-ended fashion, and thus are to be interpreted to mean "including, but not limited to... ." Also, the term "couple" or "couples" means either an indirect or direct connection. Thus, if a first component couples or is coupled to a second component, the connection between the components may be through a direct engagement of the two components, or through an indirect connection that is accomplished via other intermediate components, devices and/or connections. In addition, if the connection transfers electrical power or signals, whether analog or digital, the coupling may comprise wires or a mode of wireless electromagnetic transmission, for example, radio frequency, microwave, optical, or another mode. So too, the coupling may comprise a magnetic coupling to transfers a physical force, electrical power, or communication signals. The coupling may include any other mode of transfer known in the art, or the coupling may comprise a combination of any of these modes. The recitation "based on" means "based at least in part on." Therefore, if X is based on Y, then X may be based on Y and on any number of other factors. The word "or" is used in an inclusive manner. For example, "A or B" means any of the following: "A" alone, "B" alone, or both "A" and "B." In addition, when used herein including the claims, the word "substantially" means within a range of plus or minus 10%.

[0029] In addition, the terms "axial" and "axially" generally mean along or parallel to a given axis, while the terms "radial" and "radially" generally mean perpendicular to the axis. For instance, an axial distance refers to a distance measured along or parallel to a given axis, and a radial distance means a distance measured perpendicular to the axis. Furthermore, any reference to a relative direction or relative position is made for purpose of clarity, with examples including "top," "bottom," "up," "upper," "upward," "down," "lower," "clockwise," "left," "leftward," "right," and "right-hand." For example, a relative direction or a relative position of an object or feature may pertain to the orientation as shown in a figure or as described. If the object or feature were viewed from another orientation or were implemented in another orientation, it may be appropriate to describe the direction or position using an alternate term.

DETAILED DESCRIPTION OF THE DISCLOSED EXEMPLARY EMBODIMENTS

[0030] This disclosure presents embodiments of a medical device or apparatus, including a millirobot or a probe powered by a magnet field, configured to perform surgeries or surgical interventions (inject drug or stem cells, pierce a blockage, etc.) within tissue, including within a living body, such as a human body, an animal body, or a plant body as examples. The magnetic field that drives and steers the probe is produced outside the living body, being produced, for example, by a magnetic resonance image (MRI) scanner. The configuration of the probe includes technology that augments or efficiently utilizes the force provided by the external magnetic field alone. As a result, the probe can be steered or driven within vasculature, including blood vessels, though blood vessel walls, and into and through other tissue. The probe may enter the body or tissue through a closed surface, such as skin, or through an opening such a pore, as examples. The probes disclosed herein may be described as a biological probe, a medical probe, or a robotic probe. Embodiments of a method for performing surgeries or surgical interventions using a probe driven by a magnetic field are also disclosed.

[0031] Referring to Figure 1, in an exemplary embodiment, a probe 50 is configured to enter and travel, untethered, within living or non-living organic tissue. Probe 50 extends from a posterior end 52 to a leading or anterior end 51 along a central axis "x" and includes a tubular body 56, and a substantially blunt end cap 58 at posterior end 52, all made of bio-compatible materials, such as titanium. An elongate chamber or channel 59 extending within probe body 56 between first and second ends 52, 51. The anterior end 51 includes a taper, becoming a smaller diameter distal the opposite end 52. Anterior end 51 may include a point or tip. The tapered tip may be shaped with barbs, ridges, or other features depending on the operation that is to be accomplished. In the example of Figure 1, end 51 includes a rigid member 60 and a frustoconical ring 62 located about member 60. Rigid member 60 is configured as a tapered end cap for body 56 and includes a cylindrical portion 61 that extends from an impact surface 65 within channel 59 to the base end of ring 62 and entirely through the ring 62. Rigid member 60 also includes a conical portion 63 that extends beyond ring 62 and extends to form a tapered point or tip 64. In some embodiments, member 60 includes titanium and may be entirely titanium. Other bio-compatible materials may be used.

[0032] A resilient member 66 is located within the channel 59 and disposed adjacent the second end 52. Resilient member 66 is, for example, a compression spring 66 (a coil spring in this embodiment) mounted on a cylindrical boss 68 extending inward on cap 58. A magnetic member is located within channel 59 and is configured to move between the resilient member and the first end. As used herein, a "magnetic member" is a something that is capable of being magnetized or being attracted (or repelled) by a magnet, but the term does not require that the member be a magnet. Thus, a ferrous metal ball is an example of a magnetic member. In most of the examples disclosed herein, the magnetic member is a ball or sphere 70, having a diameter D_s and a radius r_s. In some embodiments, the magnetic member may be cylindrical or may have another shape. The diameter of channel 59 is essentially equivalent to sphere diameter, D_s, except having sufficient clearance to allow sphere 70 to move linearly and to rotate. Tubular body 56, cap 58, rigid member 60, ring 62, and spring 66 include non-magnetic material, and in at least some embodiments, are entirely non-magnetic. In some embodiments, the magnetic member, e.g. sphere 70, may include non-magnetic material as well as magnetic material. In various embodiments, the materials and configurations of components of probe 50 are selected such that probe 50 is neutrally buoyant relative to water or relative to a selected biological fluid. As examples, the volume of channel 59 and the type of gas inside channel 59 may be adjusted or selected to achieve neutrally buoyancy for probe 50. Within probe 50, sphere 70 is a magnetically-driven hammer. The engaging or impacting surfaces that cause probe 50 to move are totally enclosed inside probe 50. [0033] A few of the possible positions for the center of sphere 70 along the x-axis are indicated in Figure 1 by dashed lines. At position 70A, sphere 70 contacts spring 66 with the spring at its normal, uncompressed length. At position 70B, sphere 70 contacts impact surface 65. At position 70C, sphere 70 compresses spring 66 as much as possible without sphere 70 "bottoming-out," i.e. without contacting boss 68. The travel distance between positions 70A, 70B may be called the free length of channel 59 and is indicated by L. The travel distance between positions 70A, 70C may be called the free length of the spring and is indicated by L_cs. The free length of the spring L_cs may be described as being the maximum amount of compression of spring 66 that is intended for the design. In some instances or in some methods of operation, sphere 70 may be caused to bottom-out, contacting boss 68 occasionally or periodically.

[0034] Referring now to Figure 2, an embodiment of a medical system or apparatus 100 that includes a magnetic source 102, and a controller 104. Magnetic source 102 is configured to generate a magnetic gradient, the direction of which can be reoriented and can be oscillated or alternated at a selected "driving" frequency. In at least some embodiments, magnetic source 102 is also configured to generate a static magnetic field. In the example of Figure 2, magnetic source 102 is a magnetic resonance imaging (MRI) scanning device, which is also be designated as an MRID 102. MRID 102 includes a magnetic coil or coils 105 centered on an equipment axis 107 and forming a channel 106, and MRID 102 includes a table 108 configured to support and transport a patient 110 or sample of tissue to a location within magnetic coil 105. A probe 50 is shown operating within patient 110, who is supported on table 108. In various embodiments, probe 50 is considered to be a member of medical apparatus 100.

[0035] MRID 102 is configured to generate a magnetic field that has an associated magnetic flux density that includes a static component B₀ along axis 107 and a dynamic (changing with time) component G(Y). B₀ and G(Y) are vector fields in at least some embodiments. The main flux density B₀ magnetizes sphere 70, and the flux density G(Y) produces magnetic gradient capable of exerting magnetic forces to move sphere 70. When the apparatus of Figure 2 operates, flux density B₀ is aligned with or parallel to axis 107. The flux density G(Y) and its magnetic gradient are directed along a "gradient axis" 112. The orientation of axis 112 is selectable by controller 104 to adjust the direction of travel of probe 50. Axis 112 may be oriented at any angle 115 with respect to axis 107. (As used herein "115" is a reference numeral for an angle. The number 115 is not an angular measurement, unless stated with the units of "degrees.") Angle 115 may range from zero to 180 to 360 degrees, with 360 degrees being equivalent to 0 degrees. Axis 1 12 and angle 115 may be rotated about axis 107. Thus, gradient axis 1 12 may be oriented in any direction within the 3 -dimensional (3D) space inside channel 106. If angle 115 is zero or 180 degrees, axis 112 is aligned on or parallel to axis 107. MRID 102 may be, for example, a clinical 3T Siemens MRI scanner.

[0036] Controller 104 is coupled for signal or power communication with MRID 102 and includes a control module 1 16 and a control module 118. Controller 104 may also include a user interface or may be coupled for communication with a computer. Modules 116 & 1 18 may include any of the following: hardware, sensors, logic circuitry, and machine-readable instruction code stored in memory devices, as examples. In various embodiments, modules 1 16 & 1 18 are contained in the same or different housings or in the same or different computers, as examples. Module 1 16 includes standard technology used to control an MRID (or technology appropriate for another magnetic source). As such, module 116 is configured to control the magnetic flux density B( and to track the location or movement of a magnetic sphere or another ferromagnetic object within channel 106, using the conventional technology associated with MRI. Module 1 18 not found in a typical MRID controller. In various embodiments, module 118 is configured is configured to exchange data or control commands for the magnetic flux density B( with module 1 16 and to track and control the location or movement of a ferromagnetic object within channel 106, such as sphere 70 of probe 50. In various embodiments, module 1 18 is configured to exchange data with a sensor on a robotic probe and to track and control the location or movement of the robotic probe based on that data. As used herein, exchanging data may include one-way data transfer or two-way data transfer. Examples of probes with sensors for tracking an incorporated ferromagnetic object or hammer are described below. Data exchanged by a module 118 with a probe may be in addition to data exchanged with module 1 16. In some embodiments a controller similar to controller 104 combines the functionality of modules 1 16, 1 18 into a single control module.

[0037] In various embodiments, either module 116, 1 18 may be used to track the location of sphere 70 relative to the remainder of probe 50 to detect or predict impact of sphere 70 against surface 65 or against spring 66. This tracked information is used by module 1 16, 1 18

(i.e. by module 116 or 1 18) to control the intensity and direction of the magnetic gradient.

Some embodiments of controller 104 may use both modules 1 16, 118 to track the location of sphere 70. Aided by module 1 16, 1 18, controller 104 governs the intensity of the flux density B₀ by varying the current supplied to coils 105 and varies the dynamic flux density G(Y) and its magnetic gradient by adjusting or modulating the current supplied to coils 105.

[0038] Referring to both Figure 1 and Figure 2, during operation of apparatus 100, the magnetic gradient generates a force that acts on magnetic sphere 70. The flux density G(Y) generates a magnetic gradient. The magnetic gradient is periodically alternated along axis 112, changing between a first direction along axis 112 and a second, opposite direction along axis 112. The alternating magnetic gradient causes sphere 70 to oscillate between the spring 66 and impact surface 65, striking spring 66 and surface 65 periodically. Thus, sphere 70 may also be called a magnetically-driven hammer. The frequency at which the magnetic gradient (e.g. the dynamic flux density G( ) changes direction is called the driving frequency and is selectable. In some instances, the driving frequency of the magnetic gradient is chosen to achieve resonance for sphere 70 in regard to its travel within channel 59. At resonance, the driving frequency of the magnetic gradient is equal to the oscillation frequency of sphere 70 within channel 59 as sphere 70 repeatedly travels back and forth, striking spring 66 and surface 65 repeatedly or periodically. Between spring 66 and surface 65, sphere 70 may travel a distance equal to the value of L plus L_cs, as an example. The matched value that may be achieved for the driving frequency and the oscillation frequency may be called a resonant frequency. Essentially, at resonance, the controller 104 changes the direction of the magnetic gradient when sphere 65 impacts surface 65 at location 70B and again when sphere 65 reaches the maximum compression for spring 66 at location 70C. In at least some instances, operating the driving frequency at a resonance will maximize the velocity of sphere 70 as it oscillates. In such situations, probe 50 or sphere 70 may be said to be driven at their resonant frequency. Probe 50 or apparatus 100 may have more than one point of resonance, each corresponding to a unique value of resonant frequency, resulting, for example, from a selected maximum magnitude of the driving force from flux density G(t). Whether being driven at its resonant frequency or at some other frequency, the impact of sphere 70 against surface 65 transfers momentum from the driven sphere 70 to the remainder of probe 50, driving probe 50 in the forward direction along axis x, with tip 64 leading. The softer rebound of sphere 70 against spring 66 and the blunt outer surface at end 52 attenuate the momentum transfer and reverse travel of probe 50. As probe 50 travels under the influence of the magnetic gradient generated by coil 105, probe axis x aligns with gradient axis 112 or becomes parallel to gradient axis 112. [0039] In various embodiments, probe 50 further includes components configured to take a tissue sample from organic tissue, such as tissue of a living patient. In various embodiments probe 50 includes components configured to deliver a drug into an organic tissue disposed within the patient or configured to deliver a substance to an implanted device already disposed within the organic tissue. For example, a tip 64, ring 62, or an entire probe 50 can contain or be composed of a slow-release therapeutic drug, brachy therapy, or material for inductive heating. Figure 3 shows a probe 50A that includes a tapered tip 64A at end 51 comprising a slow-release therapeutic drug that will be left within a patent after the probe arrives at its targeted destination. In some instances, the probe components can be biocompatible or biodegradable and the probe, containing therapeutic material, can then be broken up by external sonification (e.g., ultrasound) or by localized heating after it reaches the target area. In some instances, a control signal that avoids impacts at 65 can be used to steer the probe backwards along the trajectory it entered along. As shown in Figure 4, in some instances, a tether 120 is attached to posterior end 52 of a probe 50B and can be used to pull the probe backwards. In some embodiments, tether 120 includes a communication or power coupling, such as an electrical or a fiber optic cable. As shown in Figure 5, in some instances, a member 60C and its tip 64C of a probe 50C include a sharp, hollow biopsy punch for gathering a sample. Tip 64C has internal barbs 122 to hold the tissue sample, some embodiments lack barbs. In another configuration, a probe 50D in Figure 6 includes a tapered rigid member 60D that is serrated with multiple barbs 124 spaced apart from a tip 64D. Barbs 124 face backwards, that is to say: barbs 124 point away from tip 64D, to encourage probe 50D to travel forward.

[0040] Figures 7A and 7B, show another embodiment of probe 50. A probe 50E extends from a leading or anterior end 51 to a posterior end 52 along a central axis "x" and includes a tubular probe body 56, a substantially blunt end cap 58 at posterior end 52, a tapered rigid member 60E at anterior end 51, and an extendable-retractable knife 76 movably coupled within member 60E at the leading end 51. Probe body 56 includes an internal channel 59 extending axially. A compression spring 66 is located within channel 59 at cap 58. A sphere 70 is located in channel 59. Rigid member 60E is configured as a tapered end cap for body 56 and includes a base 78 coupled at body 56, an exterior tip 64E distal body 56, a cylindrical portion 61 E extending from base 78, a conical portion 63E extending from portion 61E to tip 64E, and a pair of axially extending slots 80 oriented at 90 degrees from each other, but other angles may be utilized. Slots 80 extend axially from base 78 through tip 64E and extend radially through the outer surface of member 60E.

[0041] Knife 76 includes a pair of double-sided blades 82 that extend axially and are coupled together along axis x, forming a knife tip 83. The edges of blades 82 are serrated with multiple barbs 124 spaced apart and facing backwards, away from tip 64E, to encourage probe 50D to travel forward. Blades 82 are slidingly disposed within slots 80, being 90 degrees from each other. In at least some embodiments, all blades 82 are, together, formed as a single, integral member. Knife 76 also includes a push rod 84 that extends from the base of blades 82, through base 78, and into channel 59. Within channel 59, rod 84 includes a contact plate 85. A resilient member, which will be called knife spring 86, is located between base 78 and impact plate 85, around a portion of push rod 84. Spring 86 biased the blades 82 to be retracted into member 60E, such that tip 83 is beneath probe tip 64E. Sphere 70 is movably disposed within channel 59 between spring 66 and impact plate 85. Probe 50E may be operated as previously described regarding probe 50. As sphere 70 oscillates in channel 59, it may impact spring 66 and plate 85. As best shown in Figures 8A and 8B, probe 50E is configured so that, when given sufficient momentum by an external magnetic gradient, sphere 70 strikes plate 85 with sufficient force to cause blades 82 and knife tip 83 to slide and extend beyond tip 63E of the tapered end cap, member 60E. In general, blades 82 extend during forward motion of probe 60E. In at least some instances, when sphere 70 moves in the opposite direction, knife spring 86 causes knife 76 to retract or partially retract within member 60E as shown in Figures 7A and 7B. In some embodiments, knife tip 83 is flush with or extends beyond the probe tip 64E when blades 82 are retracted into member 60E.

[0042] Figures 9A and 9B show another embodiment of probe 50. In this example, a probe

5 OF extends from an anterior end 51 to a posterior end 52 along a central axis "x" and includes a tubular body 56, a tapered rigid member 60 at anterior end 51 , and a substantially blunt end cap 58 at posterior end 52. Rigid member 60 includes a cylindrical portion 61 that extends from an impact surface 65 within channel 59 to a conical portion 63 that terminates at an exterior tip 64. A compression spring 66 is mounted on a cylindrical boss 68 extending inward on cap 58. A sphere 70, having a diameter D_s is located in channel 59 and is free to move axially and to rotate. Probe 50F also includes a pair of axially spaced position sensors

140 configured to detect or measure the location of sphere 70. In this example, each position sensors 140 includes a laser diode 142 aligned with a corresponding light sensor 144. Probe

50F and sensors 140 are coupled for wireless or wired communication with controller 104 (Figure 2) to provide a signal when sphere 70 blocks a beam path between light laser diode 142 and the corresponding sensor 144. The first position sensor 140 is located such that its beam path is located a distance of Lf from impact surface 65 at axial location 70B, and the second position sensor 140 is located such that its beam path is located a distance of ¾ from location 70A, where sphere 70 may contact spring 66, when spring 66 is uncompressed. Preferably, distances Lf and L> are chosen so that sphere 70 can completely cross each beam path as it approaches a probe end 51, 52. Thus, the distances may be chosen such that Lf> D_s and Lb≤ (D_s - L_cs) with L_cs being the free length or maximum compression of spring 66, as previously discussed. In various embodiments, probe 50 include any of the probe tips and body configurations described herein, such as those of probes 50A, 50B, 50C, 50D, 50E. In some other embodiments, position sensors 140 use another technology for sensing sphere 70, such as a type of proximity sensor, for example. Probe 50F may be operated as previously described regarding probe 50. Modes of operation for probe 50F are discussed below.

[0043] Figure 10 shows another embodiment of probe 50. In this example, a probe 50G has the same features as probe 50F, except probe 50G has a single position sensor 140 located proximal the impact surface 65 and distal the spring 66. As defined above, sensor 140 is located at a distance of Lf from impact surface 65, which is at axial location 70B. Probe 50G and sensor 140 are coupled for wireless or wired communication with controller 104 (Figure 2) to provide a signal when sphere 70 passes by sensor 140. In various embodiments, probe 50 include any of the probe tips and body configurations described herein, such as those of probes 50A, 50B, 50C, 50D, 50E. In some embodiments, position sensors 140 use another technology for sensing sphere 70 or another magnetic member, such as a type of proximity sensor, for example. Probe 50G may be operated as previously described regarding probe 50. Modes of operation for probe 50F are discussed below.

[0044] Although the discussion above tended to focus on the example of an MRI device as a magnetic source, other controllable magnetic sources may be used to drive any of the probes 50. An example is provided in Figure 11.

[0045] Figure 11 presents an embodiment of a medical system or apparatus 200 that includes a magnetic source 202 and a controller 204. Magnetic source 202 includes multiple magnetic coils 205, located around an equipment axis 207 and forming a channel 206. Medical apparatus 200 also includes a table 208 extending through channel 206 parallel to axis 207 and an array of multiple Hall-effect sensors 214 surrounding channel 206. Sensors 214 are spaced apart about the perimeter of channel 206 and are spaced apart axially. The multiple Hall-effect sensors 214 are configured to monitor the location of a magnetic obj ect that may be located within channel 206, such as a sphere 70 (Figure 1) of a probe 50. Table 208 is configured to support a patient 210 or sample of tissue within magnetic coils 205. Coils 205 are coupled to table 208 by a mounting apparatus 209 that is configured to move coils 205 axially relative to table 208 and relative to a patient, when a patient is present. Mounting apparatus 209 includes a threaded rod, a hydraulic cylinder, or another type of actuator for moving coils 205 linearly along axis 207. A probe 50 is shown resting on the top of table 208. During operation, probe 50 would be located within channel 206. In various embodiments, probe 50 is considered to be a member of medical apparatus 200. In general, any of the probes disclosed herein may be used with magnetic source 202 and controller 204.

[0046] Magnetic source 202 is configured to generate a magnetic field that has an associated flux density, G(Y) that produces a magnetic gradient to move sphere 70. The direction of the flux density can be reoriented and can be oscillated or alternated at a selected "driving" frequency to control the movement of sphere 70. In at least some embodiments, magnetic source 202 is also configured to generate a static magnetic flux density, B₀, which can induce a magnetization within a ferromagnetic object, such as a sphere 70 to make the object susceptible to flux density G(t).

[0047] Continuing to reference Figure 11, controller 204 is coupled for signal or power communication with magnetic source 202 and mounting apparatus 209. Controller 204 includes a control module 216 and a control module 218. Controller 204 may also include a user interface or may be coupled for communication with a computer. Modules 216 & 218 may include any of the following: hardware, sensors, logic circuitry, and machine-readable instruction code stored in memory devices, as examples. In various embodiments, modules

216 & 218 are contained in the same or different housings or in the same or different computers, as examples. Module 216 is configured to control the magnetic flux density produced by coils 205 to move probe 50. Module 216 may do this, for example, by adjusting or modulating the current supplied to coils 205. Module 216 includes machine readable instructions for these purposes. Module 128 is configured to track and control the location or movement of a robotic probe 50 and its sphere 70. Module 218 includes machine readable instructions for these purposes. Module 218 is configured to exchange data with Hall-effect sensors 214 to monitor to location of sphere 70 within channel 206. In various embodiments, module 218 is also configured to exchange data with a sensor on a robotic probe, such as a sensor 140 of a probe 50F (Figure 9A), 50G (Figure 10) to measure or track the location of sphere 70 relative to the impact surface 65 (Figure 1). Thus, in one or more ways, Module 218 is configured to track the location or movement of a ferromagnetic object within channel 206, such as sphere 70 of probe 50. Module 218 is configured is configured to exchange data, including commands with module 216. In some embodiments, a controller similar to controller 204 combines the components or functionality of modules 216, 218 into a single control module. In some embodiments, in additional to or in place of Hall-effect sensors 214 or a sensor 140 on probe 50, system 200 includes a microphone coupled with module 218 to perform the tracking function by acoustically detecting the impact of sphere 70 against impact surface 65 at anterior end 51 or the contact or engagement of sphere 70 at probe posterior end 52.

[0048] Referring to Figure 2 and Figure 11, multiple modes of operation are possible for various embodiments of the robotic probes and controllers disclosed herein. As used herein, the term "operation" refers to usage of a probe or to the usage of a controller to control a probe. The term operation does not necessarily refer to medical procedure. The modes of operation include open-loop operation and closed-loop operation, depending on whether data regarding the location of sphere 70 relative to probe body 56 is used by a controller 104, 204, as sphere 70 moves within channel 59. During open-loop operation, the direction of flux density G( is periodically alternated by controller 104, 204 based on a preprogrammed sequence of switching times or a constant driving frequency. In some embodiments or instances, the driving frequency has a 50% duty cycle while in other embodiments or instances, the driving frequency has a duty cycle that is greater than or less than 50%. In some, the duty cycle is set so that the time for the forward force is less than the time for the reverse force relative to the x-axis. In some, the duty cycle is set so that the time for the reverse force is less than the time for the forward force. The location of sphere 70 relative to another component of probe 50 is not considered and, in some examples, is not measured. Thus, no feed-back of data related to the location of sphere 70 within probe 50 is utilized in the control process. Any of the probes disclosed herein may be operated in the open-loop control mode.

[0049] During a mode of closed-loop operation, the direction of the flux density G( is adjusted or alternated by controller 104, 204 based on the detected or measured locations of sphere 70 as sphere 70 approaches or engages each end 51, 52 of probe 50 repeatedly. For example, the position data for sphere 70 may be generated by the first and second sensors 140 of probe embodiment 50F in Figure 9B to achieve closed-loop operation. For each detection, the controller 104 switches the direction of flux density G(Y) to drive sphere 66 back toward the opposite end of probe channel 59. Thus, the driving frequency for flux density G(t) is adjusted based on the position data for sphere 70. The travel time between sequential impacts with surface 65 may be measured or estimated based on the position data for sphere 70. In some embodiments or instances, the driving frequency has a 50% duty cycle while in other embodiments or instances, the driving frequency has a duty cycle that is greater than or less than 50%. In some, the time for the forward force is less than the time for the reverse force. In some, the time for the reverse force is less than the time for the forward force relative to the x-axis.

[0050] During another mode of closed-loop operation, the direction the flux density G(Y) is adjusted or alternated by controller 104, 204 based on the detected or measured locations of sphere 70 as sphere 70 approaches or engages anterior end 51 of probe 50 repeatedly. More particularly, controller 104, 204 responds to sphere 70 as it approaches or impacts the impact surface 65. In this mode of operation, the location of sphere 70 relative to end 52 or spring 66 is not measured or detected, or such data is ignored by the controller. However, the time of engagement with spring 66 or the travel time between sequential impacts against surface 65 may be estimated, as will be discussed below. The travel time between sequential impacts with surface 65 may be measured or estimated. In an example, the position data for sphere 70 may be generated by the first sensor 140 that is proximal to surface 65 of probe embodiment 50F in Figure 9B. As another example, the position data for sphere 70 may be generated by the single sensor 140 located proximal to surface 65 of probe embodiment 50G in Figure 10. Again, in this mode of operation, the driving frequency for flux density G(Y) is adjusted based on the position data for sphere 70. This mode of closed-loop operation may also be called "partially closed-loop operation," due to measuring or detecting the position of sphere 70 adjacent only one end of probe body 56; whereas, the controller changes the direction of the magnetic field gradient when the probe is adjacent each of the two ends 51, 52.

[0051] During the various modes of operation, controller 104, 204 may use different or additional data when adjusting or alternating the magnetic gradient. For example, controller

104 of Figure 2 may use data related to the position of sphere 70 within the volume of channel 106. This data may be sensed by coils 105 in response to the magnetic field that is induced within sphere 70 by coils 105 and may indicate the location of probe 50 within channel 106. Optionally, because sphere 70 will be oscillating, the data sensed by coils 105 may be used to detect or estimate the position of sphere 70 relative to one or both ends 51, 52 of probe 50, to allow any of the probes disclosed herein to be operated in the closed-loop or partially closed-loop mode of operation. Likewise, controller 204 of Figure 11 may use data related to the position of sphere 70 within the volume of channel 206. This data may be generated by Hall-effect sensors 214 in response to the magnetic field of sphere 70 that, for example, may be induced by coils 105 and may indicate the location of probe 50 within channel 106. Optionally, because sphere 70 will be oscillating, the data from sensor 214 may be used to detect or estimate the position of sphere 70 relative to one or both ends 51, 52 of probe 50, to allow any of the probes disclosed herein to be operated in the closed-loop or partially closed-loop mode of operation.

[0052] In some instances of a closed-loop or a partially closed-loop mode of operation, a controller 104, 204 achieves or selects a resonant driving frequency to govern the flux density G( - When using a resonant driving frequency, the oscillations of the magnetic gradient are periodic, changing steadily with time, and the velocity of the sphere 70 becomes maximized. In other modes, the controller achieves or selects another driving frequency. Considering Figure 1 for reference, in one mode of operation, resonance is achieved for sphere 70 by changing the direction of the magnetic gradient when the velocity of sphere 70 becomes zero adjacent to either end 51, 52 of probe 50, which is immediately followed by sphere 70 changing direction due to impact. Resonance may be achieved by changing the magnetic gradient toward posterior end 52 when sphere 70 impacts surface 65 and by changing the magnetic gradient again (toward anterior end 51) when sphere 70 pushes spring 66 to a point of maximum compression but prior to bottoming-out at posterior end 52, corresponding in some instances to position 70C. As examples, the repeated impacts with surface 65 or the repeated impacts with spring 66 may be detected by a sensor 140 (Figure 9B, 10), by Hall- effect sensors 214 (Figure 11), by a magnetic coil 105, 205 (Figure 2, 11), or by an acoustic sensor(s), as described above(s).

[0053] Motion of a Magnetic Member in a Probe

[0054] The motion of a magnetic member to act as a hammer in a probe will be described with reference to probe 50 of Figure 1 and apparatus 100 in Figure 2. However, this discussion is also applicable to other probes disclosed herein and to apparatus 200 of Figure 11. The time-varying forces acting on sphere 70 as well as the time-varying position, x_s(t), and velocity, v_s(t), of sphere 70 will be discussed.

[0055] The positions of sphere 70 as it moves back-and-forth within probe body 56 may be described in terms of a position function, x_s(t), defined along the x-axis of probe 50 as a function of time, t. Some of the values of position x_s(t) are summarized in Table 1 below, based on Figures 1, and 3-5:

Table 1: Designated Positions of Sphere 70 within Probe 50

[0056] Here, L_cs is the free length of the spring, which is the maximum amount of compression of spring 66 that is intended for the selected design, without allowing sphere 70 to "bottom-out," i.e. without contacting boss 68, at the bottom of spring 66. The position function x_s(t) may be evaluated further based on the following discussion. During operation, the sphere oscillates between ends 51, 52 in repeated cycles of motion. In an example, a cycle for sphere 70 is defined to span from one impact of sphere 70 against surface 65 until the next impact against surface 65. The travel time of the sphere between impacts is the duration or period of the cycle and will be designated by At. This cycle period is influenced at least by the intensity of the magnetic force applied to sphere 70 and by properties of probe 50. Evaluation of the sphere's cycle period will be considered below. The starting or initial time for the cycle will be designated by to, and the ending time will be (to+At). Considering Table 1, at the start and at the end of a cycle, the sphere is located at position 70B, so that x_s(t = to) = L and also x_s(t = h+At) = L. The inverse of the cycle period gives the frequency of the sphere's travel cycle,/

^/s At

[0057] As introduced above, magnetic source 102 is capable of generating a magnetic flux density B(Y) that includes a static magnetic flux density B₀ along axis 107 and a dynamic magnetic flux density G(Y) thus:

B(t) = B₀ + G t) 2 [0058] As indicated, G(Y) and therefore B are variable with time, being adjustable by controller 104. B₀ and G(Y) are vectors in at least some embodiments. B₀ may be zero in some embodiments. The static flux density B₀ magnetizes sphere 70 in some embodiments, and the flux density G(Y) produces the forces necessary to move sphere 70. When the apparatus of Figure 2 operates, the flux density B₀ is aligned with or parallel to axis 107. The magnetic gradient generated by G(Y) is directed along a "gradient axis" 112. The orientation of axis 112 with respect to axis 107 is adjustable by controller 204. The magnetic force vector, F(t) produced by the magnetic flux density at a time, t, may be evaluated using equation 2:

F(t) = V(m - B(t)) 3

[0059] Here m is the magnetic moment of the sphere, and B(t) is the external flux density at a time t. Because sphere 70 is constrained within tubular probe body 56, only the x- component of magnetic force vector, F(t) acts to move sphere 70, causing it to move between probe ends 51, 52. So, the net magnetic force acting on sphere 70 in the x-direction at time t is:

fmag(t) = F_*(0 4

[0060] Controller 104 can be optimized to always choose B(t) such that the magnitude of the magnetic force is always constant and maximized for a giving power setting of coils 102; therefore, for any value of time, t:

[0061] Equations 5 says that, during operation, the magnetic force F_mag(t) = F_x exerted on sphere 70 by magnetic source 102 has a constant value, F^, that is either acting in the positive direction along the x-axis, which is a forward force, or is acting in the negative direction along the x-axis which is a reverse force, acting opposite the desired direction of travel of probe 50. This maximized value of magnetic force, F^, is selectable by adjusting the power or current supplied to coils 102 using controller 104. The controller is programmed to alternate the direction of magnetic force F_mag(t) = ¥_x, as described above.

The example cycle, as defined, starts at or just after an impact with surface 65 so that during the first portion of a cycle, sphere 70 is traveling toward spring 66. Therefore, during the first portion of a cycle, the magnetic force is made to act in the negative x-direction, starting from the initial time, to, until the completion of a reverse force duration, Atr_f, which is a time period that is selectable by the controller. The cycle's initial time and reverse force duration establish a switching for the magnetic force. After the reverse force duration time is completed, the controller switches the magnetic gradient to apply the magnetic force in the positive x-direction during a forward force duration. In some embodiments, the forward force duration continues until impact occurs at surface 65. When optimized to achieve a resonant state, controller 104 applies the magnetic force in the same direction as the velocity, v_s(t), of the sphere, therefore equation 5 can be rewritten as:

6

[0062] The function sign( ) returns 1 if the argument is positive and -1 otherwise. So, a change in velocity from a negative to a positive direction relative to the x-axis determines the reverse force duration, At^. Determining of the velocity of the sphere will be discussed below.

[0063] The force of spring 66 is only active on sphere 70 when the spring is in contact with the sphere. The spring force may be written as a function of the sphere's position, x_s t), which varies with time:

^spring (·½) ^

[0064] The force of the spring may also be written as F_sprin5(x_s (t)), and k is the spring constant. Combining the magnetic force of equation 5 and the spring force of equation 7, the total force that acts on sphere 70 is:

[0065] As sphere 70 oscillates, the force acting on the sphere, F_s(t) applies an acceleration to sphere 70 that is inversely proportional to the s here's mass, m_s:

m_s

[0066] To calculate the time-varying velocity of the sphere, v_s(t), at a time t, acceleration, s(t), may be integrated from the initial time t₀ of the sphere's travel cycle to the selected time t and then added to an estimated or a known initial velocit , v_s(t = to),

[0067] The position of the sphere, x_s (t), may be evaluated by integrating equation 10 over the same span of time: from initial time t₀ to the selected time t. By evaluating and also integrating equation 10 from initial time to to the time t = to+At and then solving for At, the cycle period At may be determined. Iteration may be used in some cases. Thus, the length of a travel period for sphere 50, At, may be solved numerically or may be measured by apparatus 100 using magnetic source 102 or sensor 140, which are examples that are described above.

[0068] The velocity that the sphere achieves just as impact occurs at surface 65 will be called the impact velocity, v_\mv. The impact velocity is the final value of velocity for the time period, so v_\mv = v_s(t = t₀+At). These equations may be solved iteratively for sequential time periods. During the iteration, the initial velocity, v_s(t₀), for a current cycle or period may be set to a value based on the impact velocity of the sphere from the previous time period. The relationship between these velocities is based on the coefficient of restitution, e, of impact surface 65, which is related to the mechanical properties of surface 65 and indicates the capability of surface 65 to return to the sphere the momentum that surface 65 receives during impact. The coefficient of restitution may have a value 0 < e < 1. Values of e closer to 1 enable a faster resonance frequency. At the start of the current time period, just after a zero- velocity condition, the velocity of the sphere is:

v_s(t₀) = -e ^■ v _mp 11

[0069] The negative superscript on the variable for impact velocity indicates that this is the value from calculations or measurements of the previous time period. The new or current time period starts just after impact with surface 65, which has caused sphere 70 to change directions, so that sphere 70 starts a cycle by traveling from surface 65 toward spring 66. This change in direction is accounted by the negative sign after the equal sign. Based on equation 11, the initial velocity, v_s(to), for a travel cycle of sphere 60 may also be called a post impact velocity.

[0070] From the equations given above, a resonant driving frequency can be generated by controller 104 to drive the flux density G(Y) such that G(Y) always points in the same direction as the velocity v_s(t) of the sphere. For a selected value of magnetic force, F^, an impact velocity at resonance, Vj_{mp res}, for a selected probe can be evaluated as:

[0071] In equation 12, m_s is the mass of the sphere, e is the coefficient of restitution for the impact surface, and L is the travel distance between the uncompressed spring 66 and impact surface 65, as shown in Figure 1. and k were defined above. The radius of sphere 70 indirectly influences the impact velocity through and m_s, both of which depend on the volume of the sphere.

[0072] Operating at a resonance condition can be beneficial in various situations or for various embodiments. Equation 12 provides a method for determining an impact velocity at resonance. Next, a method for achieving a resonance condition will be considered.

[0073] Figure 12 provides a graph that can used to determine operating parameters that lead to or achieve a resonance condition for a probe as disclosed herein, such as probe 50. Figure 12 is unique to a particular embodiment of probe 50, and must be reconstructed based on an embodiment's characteristics to be applied to some embodiments. Figure 12 plots in seconds the sphere's cycle period, At, between impacts as a function of reverse force duration in seconds, At^, for different initial velocities, v_s(Y₀). The multiple curves labeled according to a value of initial velocity, v_s(Y₀), are the functions of cycle period with respect to reverse force duration. Other similar functions may be plotted between these curves or outside the bounds of these curves in accordance with principles described herein. Various regimes of operation are labeled with lower-case Roman numerals. Some of these regimes are indicated by curves extending from the lower left to the upper right, passing through multiple of the functions.

[0074] The graph shows that for a selected or estimated value of initial velocity, v_s(to), an optimum value for At^ exists. An iterative optimization algorithm can be used to progressively converge toward the optimum value for reverse force duration, At^. A small change is applied to the reverse force duration for each iteration. The resulting variation on the next cycle period, At, is observed by measurement or calculation of At. For example, on a majority of the graph, the curves for initial velocity, v_s(Y₀), are generally horizontal or they curve generally from horizontal on the right, toward vertical on the left. For these regions, if the value of cycle period, At, has decreased, then the reverse force duration, Δ¾ is changed again in the same direction during the next iteration. For example, increase At^ if previously increased, or decrease Atr_f if previously decreased. If At has increased, then At^ is changed in the opposite direction. This process will lead toward an optimum value for reverse force duration, A¾ that corresponds to a local minimum value of cycle period, At, for the current cycle's value of initial velocity, v_s(Y₀). This optimum value is situated on a curve iv that intersects each of the graphed functions of At^ which are labeled according to a value of initial velocity. A minimum value of cycle period, At, is consider to be optimal because it corresponds to a maximizing of the velocity, v_s(t), of the sphere during a travel cycle, which is an indicator of resonance. A gradient descent optimization can be used to increase the convergence rate of this algorithm. During iteration, the equation of curve iv can be used to calculate the next t_s value to apply. The value of initial velocity changes in the next iteration. The intersection of the optimum line iv and the line for At as a function of the new v_s(Y₀) can be calculated to determine the new optimum value for Ata. This process may iterate indefinitely during the simulation or operation of a probe and it naturally converges to achieve and maintain an optimum value for At^.

[0075] Considering Figure 12 again, during operation of a probe, the graph provides a method for estimating the initial velocity, v_s(Y₀), of a sphere's travel cycle, as a function of the reverse force duration t_s and the sphere's cycle period At, e.g. the time between impacts with surface 65. To accomplish this, the reverse force duration, t_s, can be selected using control 104, and the cycle period At (e.g., the time between impacts with surface 65) can be measured based on detecting the location of sphere 70 during a cycle. Using the values of t_s and At as a coordinate for the graph, a corresponding value of initial velocity, v_s(Y₀), may be located or estimated. This process for estimating the initial velocity, v_s(Y₀), may be performed for multiple cycles or may provide an averaged result based on multiple cycles. The estimated values of initial velocity can be used to progressively choose Ata values that bring the sphere to a condition of resonance during closed-loop or partially closed-loop operation.

[0076] A method of operating a probe using a magnetic field source may be developed based on the principles disclosed herein. The method may be used to operate various of the probe embodiments disclosed herein or embodiments of the apparatuses 100, 200, as examples.

[0077] In general, other than the differences noted above, the probe embodiments 50A, 50B, 50C, 50D, 50E, 50F are similar to probe 50 and may replace probe 50 to accomplish one or any of the uses of probe 50 discussed herein, including use in an apparatus 100, 200. As with probe 50, probes 50A, 50B, 50C, 50D, 50E, 50F may include a magnetic member that is cylindrical or has another suitable shape in place of sphere 70. In some embodiments, the magnetic member is not magnetized until a coil or coils 102, 202 induces a magnetic field in the magnetic member, and in some embodiments, the magnetic member includes a permanent magnet. In addition to or in place of the methods discussed above, in some embodiments, the position of sphere 70 relative to probe body 56 may be determined or estimated with the aid of a X-ray or ultrasound imaging technology.

[0078] The various probe embodiments disclosed herein may be used in a similar manner. For example, a method for performing surgeries or surgical interventions using a probe (such as probe embodiments 50 as well as 50A - 50F) driven by a magnetic field includes: providing a probe having a magnetic member configured to oscillate within an internal channel of the probe body; and controlling a magnetic gradient to cause the magnetic member to oscillate within the probe body. In some embodiments, the method also includes: monitoring the movement of the magnetic member relative to the probe body; wherein controlling a magnetic gradient includes adjusting the magnetic gradient based on the movement of the magnetic member relative to the probe body. In some embodiments, adjusting the magnetic gradient includes performing an iteration step that includes:

selecting a length of time for a reverse force duration;

applying a magnetic force that pulls the magnetic member toward the second end during a reverse force duration;

applying a magnetic force that pulls the magnetic member toward the first end after completing the reverse force duration;;

determining a cycle period between impacts of the magnetic member with an impact surface that is proximal the first end based on monitoring the movement of the magnetic member;

developing a cycle period comparison based on the cycle period and a member selected from among a plurality of previously determined cycle periods;

changing the length of time for the reverse force duration based on the result of the cycle period comparison;

repeating the iteration step until the cycle period is a minimum value as compared to at least two members of the plurality of previously determined cycle periods; wherein the cycle period becomes a member of the plurality of previously determined cycle periods before developing a cycle period comparison in the subsequent iteration step.

[0079] In some embodiments, the method further includes causing the probe to move into the organic tissue; and wherein controlling a magnetic gradient causes the magnetic member to oscillate within the probe body at a resonant frequency. The method may include causing the probe to move within the body of a living patient by controlling a magnetic gradient. The method may also include taking a tissue sample from the organic tissue using the probe; and causing the probe to move into the organic tissue. In some embodiments, the method also includes delivering a drug into an interior portion of the organic tissue using the probe.

[0080] In its various embodiments, probe 50 and apparatus 100, 200 are suited for experimental use. Some embodiments created in accordance with principles described herein may be approved for medical use, which may include use inside a living human body. One or more embodiments may be suitable for additional uses that are unrelated to the medical field.

[0081] While exemplary embodiments have been shown and described, modifications thereof can be made by one of ordinary skill in the art without departing from the scope or teachings herein. The embodiments described herein are exemplary only and are not limiting. Many variations, combinations, and modifications of the systems, apparatuses, and processes described herein are possible and are within the scope of the disclosure. Accordingly, the scope of protection is not limited to the embodiments described herein, but is only limited by the claims that follow, the scope of which shall include all equivalents of the subject matter of the claims. The inclusion of any particular method step or operation within the written description or a figure does not necessarily mean that the particular step or operation is necessary to the method. The steps or operations of a method listed in the specification or the claims may be performed in any feasible order, except for those particular steps or operations in the claims, if any, for which a sequence is expressly stated. In some implementations two or more of the method steps or operations may be performed in parallel, rather than serially.

Claims

CLAIMS What is claimed is:

1. Medical apparatus for probing into organic tissue, the medical apparatus including a probe that comprises:

a central axis;

a probe body extending along the axis and having a first end and a second end, the first end having a taper;

a channel extending within the probe body between the first and second ends;

a resilient member within the channel and disposed adjacent the second end; and a magnetic member disposed within the channel and configured to move between the resilient member and the first end.

2. The medical apparatus of claim 1 wherein the probe includes an impact surface disposed within the channel at the first end, and;

wherein the magnetic member is to strike periodically the impact surface when a force generated by an alternating magnetic gradient acts on the magnetic member.

3. The medical apparatus of claim 2 further comprising a rigid member extending from the impact surface and forming a tapered tip at the first end.

4. The medical apparatus of claim 1 wherein the medical device comprises biocompatible materials suitable for entry into living tissue of the body of a living patient.

5. The medical apparatus of claim 1 wherein the magnetic member is a sphere.

6. The medical apparatus of claim 1 further comprising a magnetic source configured to generate an alternating magnetic gradient, which reverses direction repeatedly;

wherein the probe includes an impact surface disposed within the channel at the first end;

wherein the alternating magnetic gradient is configured to cause the magnetic member to oscillate between the resilient member and the impact surface.

7. The medical apparatus of claim 6 wherein the alternating magnetic gradient is configured to cause the magnetic member to oscillate between the resilient member and the impact surface at a resonant frequency.

8. The medical apparatus of claim 7 wherein the magnetic source is a magnetic resonance imaging device (MRID).

9. A method for performing surgeries or surgical interventions using a probe driven by a magnetic field, the method comprising:

providing a probe for entry into organic tissue, the probe comprising:

a central axis;

a probe body extending along the axis and having a first end and a second end, the first end having a taper;

a channel extending within the probe body between the first and second ends; a resilient member within the channel and disposed adjacent the second end; and

a magnetic member disposed within the channel and configured to move between the resilient member and the first end; and controlling a magnetic gradient to cause the magnetic member to oscillate within the probe body.

10. The method of claim 9 further comprising:

monitoring the movement of the magnetic member relative to the probe body; and wherein controlling a magnetic gradient includes adjusting the magnetic gradient based on the movement of the magnetic member relative to the probe body.

1 1. The method of claim 10 wherein the probe further comprises an impact surface disposed proximal the first end;

wherein adjusting the magnetic gradient includes performing an iteration step that includes:

selecting a length of time for a reverse force duration;

applying a magnetic force that pulls the magnetic member toward the second end during a reverse force duration; applying a magnetic force that pulls the magnetic member toward the first end after completing the reverse force duration;

determining a cycle period between impacts of the magnetic member with the impact surface based on monitoring the movement of the magnetic member;

developing a cycle period comparison based on the cycle period and a member selected from among a plurality of previously determined cycle periods;

changing the length of time for the reverse force duration based on the result of the cycle period comparison;

repeating the iteration step until the cycle period is a minimum value as compared to at least two members of the plurality of previously determined cycle periods;

wherein the cycle period becomes a member of the plurality of previously determined cycle periods before developing a cycle period comparison in a subsequent iteration step;

12. The method of claim 10 further comprising causing the probe to move into organic tissue; and

wherein controlling a magnetic gradient causes the magnetic member to oscillate within the probe body at a resonant frequency.

13. The method of claim 10 further comprising:

taking a tissue sample from the organic tissue using the probe.

14. The method of claim 10 further comprising:

delivering a drug into the organic tissue using the probe.

15. The method of claim 9 wherein the organic tissue is part of the body of a living patient, method further comprising causing the probe to move within the body of the patient by controlling a magnetic gradient.

16. Surgical apparatus for probing into organic tissue, comprising: a probe body having a first end and a second end, the first end having a taper;

an elongate chamber within the probe body;

a resilient member within the chamber and disposed adjacent the second end;

an impact surface disposed within the chamber opposite from the resilient member; and

a magnetic member disposed within the chamber and configured to move within the chamber between the resilient member and the impact surface.

17. The surgical apparatus of claim 16 wherein the magnetic member is configured to strike periodically the impact surface when a force generated by an alternating magnetic gradient acts on the magnetic member.

18. The surgical apparatus of claim 16 further comprising a knife at the first end.

19. The surgical apparatus of claim 16 further comprising a tissue sampling device at the first end and selected from the group consisting of barbs and biopsy punch.

20. The surgical apparatus of claim 16 further comprising a magnetic source configured to generate an alternating magnetic gradient, which reverses direction repeatedly, and to cause the magnetic member to oscillate between the resilient member and the impact surface.