Systems and methods for controlling multi-degree of freedom bending and bending length of a robot steerable guidewire for coaxial alignment

Abstract

The present disclosure relates generally to systems and methods for guidewire control, and more particularly to systems and methods for controlling the multi-degree of freedom bending and bend length of a coaxially aligned robotically steerable guidewire. The present disclosure is manually actuated, and in other aspects is automated / robotically actuated.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 013,425, filed April 21, 2020, pursuant to 35 USC §119(e), the entire contents of which are incorporated herein by reference as if set forth herein.

[0003] Statement regarding federally funded research or development

[0004] This invention was completed with government support, granted by the National Institutes of Health (NIH) under license number R01HL144714. The government holds certain rights to this invention.

[0005] Names of the parties to the joint research agreement

[0006] not applicable

[0007] sequence list

[0008] not applicable

[0009] Statements regarding prior disclosures by the inventors or co-inventors

[0010] not applicable Technical Field

[0011] This disclosure generally relates to systems and methods for guidewire control, and more particularly to systems and methods for controlling the multi-degree-of-freedom bending and bending length of a robot-manipulated guidewire in coaxial alignment. Background Technology

[0012] Cardiovascular disease (CVD), such as chronic heart disease, stroke, or high blood pressure, is one of the top ten leading causes of death in the United States, contributing approximately $330 billion in direct and indirect costs in 2014. Most minimally invasive treatments for cardiovascular disease begin with a clinician inserting a guidewire into the appropriate location within the patient's vascular system and guiding it to the blocked (or diseased) blood vessel. In most procedures for treating peripheral artery disease (PAD), the surgeon must use various catheters draped over the guidewire. These catheters may be equipped with tools for performing plaque resection (e.g., microdrills) or with drug delivery units (in the form of drug-coated balloons) to help prevent further deposition on the artery.

[0013] A guidewire is a passive wire typically made of nitinol with a diameter of 0.3556 mm to 0.889 mm (typical wire in the range of 0.3556 mm to 0.4572 mm or commonly referred to as 0.014” to 0.018” guidewire), depending on the interventional pathway, with a length of 50 cm to 260 cm. Once the guidewire is navigated to the occluded vasculature, the clinician can use the guidewire as a carrier for various catheters that help clear the occlusion.

[0014] The physician manually steers the guidewire to the target artery by proximally inserting, retracting, and rotating the guidewire base, which is the only degree of freedom (DoF) available to the clinician to control the distal tip, while observing the guidewire’s motion on real-time fluoroscopic images. This dexterous navigation of the guidewire tip under two-dimensional visual feedback is difficult and time-consuming and requires a high level of experience. Furthermore, angulation of the vessel, vessel tortuosity, or calcification can make this control challenging and can lead to guidewire kinking and breakage.

[0015] Replacing the guidewire with an alternative guidewire having a different stiffness / curvature is possible, but requires multiple sets of guidewires and repeated exchange can cause vascular injury. These challenges faced with manual navigation result in prolonged procedure time and increased radiation exposure for the patient, clinician, and operating room staff.

[0016] Traditional steerable guidewires and microcatheters have limitations. Due to size limitations on guidewire diameter, most guidewires are either manually actuated or externally automatically / robotically actuated using, for example, magnetic sources, or are tendon-driven. The bulky equipment required for magnetic actuation can interfere with imaging modalities such as fluoroscopy and magnetic resonance imaging (MRI). Tendon-driven designs have fixed joint lengths and do not perform any type of “follow-the-leader” motion, making these guidewires difficult to navigate into tortuous anatomical pathways.

[0017] To implement follow-the-leader motion, traditional tendon-driven continuum robots have extendable curved segments. However, their limited range of extendable lengths makes it difficult to achieve ideal follow-the-leader motion and their size / complexity makes them unsuitable for guidewire applications.

[0018] Traditional mechanisms such as concentric tube assemblies allow the robot’s curvature and bend angle to vary with joint length, but suffer from complex modeling and instability due to the presence of multiple minimum energy states that cause the robot to “snap” from one minimum energy state to another during a procedure, which can result in unintended trauma to the patient.

[0019] One innovative approach to avoid these issues is to introduce notched structures within individual independent tubular elements.

[0020] However, in all conventional designs, the coupling between the joint length and the bend angle of the system is preserved, i.e., the bend length and bend angle of these systems cannot be controlled independently.

[0021] Accordingly, there is a need for technical innovation to provide a system and method of guidewire control that overcomes the limitations of conventional systems and methods. Accordingly, it is an object of the present invention to provide a tendon-driven coaxially aligned steerable guidewire robot that can simultaneously and independently control the bend angle and length of the bend segments, thereby performing a "follow-the-leader" motion at its distal bend segment. SUMMARY

[0022] According to exemplary embodiments of the present invention, a novel coaxially aligned steerable guidewire is briefly described that is sized to fit the vasculature and provides a variable curvature and independently controlled bend length at the distal end. In some exemplary embodiments, the present invention is manually actuated, while in other exemplary embodiments, the present invention is automatically / robotically actuated.

[0023] In one exemplary embodiment of the present invention, a robotic system includes three coaxially aligned hollow bodies or tubes, with a single tendon extending centrally through the length of the robot. The tendon includes a super-elastic wire. The super-elastic material can include any material that can be reversibly deformed up to a strain of about 10%. For example, in some embodiments, various components of the present invention can be composed of Nitinol. However, it should be appreciated that various components of the present invention can be composed of any material, which if used in a biological environment, can include a biocompatible material that is not necessarily super-elastic, including but not limited to biocompatible metals, biocompatible alloys, biocompatible plastics, or materials containing biocompatible coatings, and the like. Other biocompatible materials can include, for example, but are not limited to, titanium or stainless steel, and the like. In one exemplary embodiment, the outer tubular element is made of micro-machined Nitinol, allowing the robot to bend at various segments of the robot driven by the tendon, thereby achieving a variable bend curvature, while a stainless steel inner tube controls the bend length of the robot. By changing the relative positions of the various tubes and tendon by inserting and retracting throughout the assembly, various joint lengths and curvatures can be achieved, enabling a follow-the-leader motion. A controller controls the distal tip of the robot.

[0024] The entire robotic assembly can be miniaturized to a total outer diameter that fits within the realm of a micro-steerable robotic guidewire. The guidewire can advance its distal end through a complex vasculature with varying curvatures with minimal interaction and support from the vessel wall. The present invention can perform a vascular intervention procedure with a guidewire navigation system, thereby avoiding the replacement of a substitute guidewire, which significantly shortens the procedure time and reduces the workload. In some embodiments, for example, in the case of using a guidewire through an artery, the guidewire tip can have a width of about 0.1 mm to about 0.9 mm. In some embodiments, the width of the guidewire tip can be about 0.3 mm, about 0.33 mm, about 0.35 mm, about 0.4 mm, about 0.45 mm, about 0.50 mm, about 0.55 mm, about 0.60 mm, about 0.65 mm, about 0.7 mm, about 0.75 mm, about 0.78 mm, about 0.8 mm, about 0.85 mm, about 0.88 mm, about 0.89 mm, or about 0.9 mm. In some embodiments, the width of the guidewire can be about 0.31 mm to about 0.34 mm, about 0.36 mm to about 0.39 mm, about 0.41 mm to about 0.44 mm, about 0.46 mm to about 0.49 mm, about 0.51 mm to about 0.54 mm, about 0.56 mm to about 0.59 mm, about 0.61 mm to about 0.64 mm, about 0.66 mm to about 0.69 mm, about 0.71 mm to about 0.74 mm, about 0.76 mm to about 0.79 mm, about 0.81 mm to about 0.84 mm, or about 0.86 mm to about 0.89 mm. In an embodiment, the guidewire tip can have a width greater than about 1.0 mm. For example, in pediatric neurosurgery, an endoscope tool having a width of about 2.0 mm can be used.

[0025] In another exemplary embodiment of the present invention, a robotic steerable guidewire system includes a path-providing guide comprising: coaxially arranged tubular elements and a tendon connected to one of the tubular elements, wherein the path-providing guide has a proximal portion and a distal portion, the path-providing guide is configured to position a distal end of a guidewire to a destination; and a control unit operably connected to the path-providing guide and configured to one or more of: control relative axial alignment of the tubular elements, control relative lateral alignment of the tubular elements, control relative rotational alignment of the tubular elements, and control travel of the tendon, wherein the path-providing guide and the control unit are cooperatively configured to simultaneously and independently control a curvature of the distal portion of the path-providing guide and control an arc length of the distal portion of the path-providing guide.

[0026] One inventive feature of the present invention is to adjust the stiffness / compliance of the length of the guide along the delivery path to become generally less stiff from its proximal end to its distal end, thereby providing innovative control over both its curvature and its length of bend for the distal end. This can be accomplished in a variety of ways. The various segments of the guide of the delivery path can have a relatively uniform stiffness along their length, where the stiffness over the length of the guide of the delivery path can be adjusted in discrete "steps" via the segments. The stiffness can also be controlled by various types of stiffness features on / in one or more tubular elements. For example, the wall thickness of a tubular element can vary along its length to provide a varying stiffness profile along the length of the segment, and thus a varying stiffness profile along the length of the guide of the delivery path. Various other mechanisms can be utilized to vary the stiffness profile, e.g., a change in cross-sectional profile, a change in material composition of the segment, a first material (material mixture) having a first stiffness and another portion / segment of the guide of the delivery path comprising a second material (material mixture) having a second stiffness. In another exemplary embodiment, the stiffness feature can comprise a plurality of notches / a set of notches along a portion of the length of the tubular element. These sets of notches can have the same length or different lengths.

[0027] The coaxially arranged tubular elements can comprise: an inner tubular element having an inner channel; an intermediate tubular element having a stiffness feature comprising a set of notches along at least a portion of the length of the intermediate tubular element; and an outer tubular element having a stiffness feature comprising a set of notches along at least a portion of the length of the outer tubular element, where the tubular elements each have suitable cross-sectional dimensions such that a guidewire is rotatably and laterally displaceable within the inner channel of the inner tubular element, the inner tubular element is rotatably and laterally displaceable within the intermediate tubular element, and the intermediate tubular element is rotatably and laterally displaceable within the outer tubular element.

[0028] The interaction between the sets of notches is useful to vary the stiffness of the guide of the delivery path along its length to become generally less stiff from its proximal end to its distal end, thereby providing innovative control over both its curvature and its length of bend for the distal end. The sets of notches can have the same length or different lengths. The intermediate tubular element can have a length defined from a proximal end to a distal end, and the set of notches begins at an intermediate position of the intermediate tubular element and extends to the distal end of the intermediate tubular element.

[0029] The outer tubular element can have a length defined from a proximal end to a distal end, and the set of notches begins at an intermediate position of the outer tubular element and extends to the distal end of the outer tubular element.

[0030] The length of the set of notches of the outer tubular element can be the same as the length of the set of notches of the intermediate tubular element, or they can be different. For example, in an exemplary embodiment, the length of the set of notches of the outer tubular element is greater than the length of the set of notches of the intermediate tubular element.

[0031] The set of notches of the outer tubular element can have the same phase or a phase difference from the set of notches of the intermediate tubular element. Having different phases can facilitate operational independence of the intermediate tubular element from the outer tubular element, for example, enabling the intermediate tubular element to be operatively rotatably and laterally displaced within the outer tubular element.

[0032] For example, the sets of notches can be offset from each other by 5°, 10°, 15°, 20°, 35°, 30°, 35°, 40°, 45°, 50°, 55°, 60°, 65°, 70°, 75°, 80°, 85°, 90°, 95°, 100°, 105°, 110°, 115°, 120°, 125°, 130°, 135°, 140°, 145°, 150°, 155°, 160°, 165°, 170°, 175°, or 180°. In some embodiments, the sets of notches can be offset from each other by 1° to 5°, 6° to 10°, 11° to 15°, 16° to 20°, 21° to 25°, 26° to 30°, 30° to 45°, 45° to 60°, 60° to 75°, 75° to 90°, 90° to 100°, 100° to 120°, 120° to 135°, 135° to 150°, 150° to 160°, 160° to 175°, or 175° to 180°. The phase (or phases) of the notches within a single set of notches can also vary.

[0033] Each notch can be any geometric shape. In an exemplary embodiment, the recesses can be rectangular. In other embodiments, the recesses can be, for example, sinusoidal or triangular. In some embodiments, the recesses can have different shapes. In other embodiments, the shapes can differ between the sets of notches (one set having one shape and another set having a different shape), and the shapes of the notches within a single set of notches can also differ. For example, within a single set of notches, a portion can have rectangular notches, a portion can have sinusoidal notches, a portion can have triangular notches, and / or the spacing of the notches within a single set can also vary along the length. In essence, the notch geometry can vary along the length of the element. In an embodiment, the shape of the recesses can be selected from the group consisting of rectangular, sinusoidal, semicircular, or triangular.

[0034] Multiple sets of notches can form a unidirectional asymmetric notch articulation of the intermediate and outer tubular elements. Asymmetric notches can be described as notches that can cause the neutral bending plane of the device to shift towards the outer edge of the device, rather than along the central axis of the device as is typically seen in the case of symmetric notches. The asymmetric pattern of notches can allow the guidewire tip to bend in one direction in the plane of the notch cut with a longer moment arm, allowing for a greater range of motion.

[0035] The guidewire tip can be defined by a width and a length. The notches can be defined by a depth. In some embodiments, the depth of the notches can be greater than 50% of the width of the guidewire tip. In some embodiments, the depth of the notches can be about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, or about 95% of the width of the guidewire tip. In some embodiments, the depth of the notches can be about 51% to about 54%, about 56% to about 59%, about 61% to about 64%, about 66% to about 69%, about 71% to about 74%, about 76% to about 79%, about 81% to about 84%, about 86% to about 89%, or about 91% to about 94% of the width of the guidewire tip. In other embodiments, the depth of the notches can be 50% or less of the width of the guidewire tip. For example, in some embodiments, the depth of the notches can be about 10%, about 15%, about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, or about 50% of the width of the guidewire tip. In some embodiments, the depth of the notches can be about 11% to about 14%, about 16% to about 19%, about 21% to about 24%, about 26% to about 29%, about 31% to about 34%, about 36% to about 39%, about 41% to about 44%, or about 46% to about 49% of the width of the guidewire tip. Indeed, in some embodiments, not every notch in the plurality of notches need have the same depth, such that the depth can vary between notches. In an embodiment, the notches can be located at the same location and no more than 50% of the width of the tubular element. In other embodiments, the notches can be located at the same location and can be more than 50% of the width of the tubular element. In embodiments having notches located at the same location, the notches can be about 25% of the outer circumference of the tubular element body. In embodiments having notches located at the same location, the articulation can move with two degrees of freedom due to the notches being located at the same location.

[0036] The path-providing guide can further have an intermediate portion, wherein the rigidity of the proximal portion of the path-providing guide is greater than the rigidity of the intermediate portion of the path-providing guide, and wherein the rigidity of the intermediate portion of the path-providing guide is greater than the rigidity of the distal portion of the path-providing guide.

[0037] The stiffness of each portion of the path-providing guide can be controlled by one or more of relative axial alignment of the tubular elements, relative lateral alignment of the tubular elements, relative rotational alignment of the tubular elements, and travel of the tendon, such that a proximal portion of the path-providing guide is a length of the path-providing guide comprising a first portion of the inner tubular element, a first portion of the middle tubular element without the set of notches, and a first portion of the outer tubular element with the set of notches arranged coaxially, a middle portion of the path-providing guide is a length of the path-providing guide comprising a second portion of the inner tubular element, a second portion of the middle tubular element with the set of notches, and a second portion of the outer tubular element with the set of notches arranged coaxially, wherein the first and second portions of the inner tubular element comprise a full length of the inner tubular element, and a distal portion of the path-providing guide is a length of the path-providing guide comprising a third portion of the middle tubular element with the set of notches and a third portion of the outer tubular element with the set of notches arranged coaxially.

[0038] In some embodiments, the present invention is part of an entire guidewire system, with the part only being at the distal portion to provide the beneficial compliance control. That is, the present invention does not need to incorporate the features of the present invention from end to end, but rather more like a "quick connect" with an end portion of another device. Thus, the present invention can be "retrofitted" onto a prior device to provide the beneficial capabilities of the present invention to other conventional systems.

[0039] In another exemplary embodiment of the present invention, a steerable guidewire system includes a path-providing guide comprising a proximal portion and a distal portion, the path-providing guide configured to position a distal end of a guidewire to a destination, and a control unit operably connected to the path-providing guide, wherein the path-providing guide and the control unit are cooperatively configured to simultaneously and independently control a curvature of the distal portion of the path-providing guide and control an arc length of the distal portion of the path-providing guide.

[0040] The path-providing guide can include tubular elements arranged coaxially and a tendon connected to one of the tubular elements, and the control unit can be configured to control one or more of relative axial alignment of the tubular elements, relative lateral alignment of the tubular elements, relative rotational alignment of the tubular elements, and travel of the tendon.

[0041] The stiffness of the proximal portion of the path-providing guide can be greater than the stiffness of the distal portion of the path-providing guide.

[0042] In another exemplary embodiment of the invention, a robotically steerable guidewire system includes a path-providing guide comprising at least three tubular elements: an inner tubular element having an inner channel, a first intermediate tubular element having a rigidity feature along at least a portion of its length, a second intermediate tubular element (and possibly other intermediate tubular elements) having a rigidity feature along at least a portion of its length, and an outer tubular element having a rigidity feature along at least a portion of its length. As noted, in this embodiment, the path-providing guide can include multiple intermediate tubular elements.

[0043] A control module is operatively connected to the path-providing guide, wherein the control module is configured to laterally shift the relative position of the inner tubular element with respect to the first intermediate tubular element, rotationally shift the relative position of the first intermediate tubular element with respect to the outer tubular element, and laterally shift the relative position of the outer tubular element with respect to the first intermediate tubular element, wherein one or more of these shifts of the tubular elements results in the creation of at least three regions of rigidity along the length of the path-providing guide: a proximal region having a greater rigidity than a middle region, and the middle region having a greater rigidity than a distal region, wherein a guidewire is operatively configured to be fed through the length of the path-providing guide and guided to a destination via the variable flexibility and arc length of the distal region of the path-providing guide.

[0044] In another exemplary embodiment of the invention, a method of steering a distal end of a guidewire along a tortuous path to a destination includes: feeding the guidewire through a path-providing guide having a distal portion through which the distal end of the guidewire is configured to exit; and simultaneously and independently controlling a curvature of the distal portion of the path-providing guide and an arc length of the distal portion of the path-providing guide along the tortuous path.

[0045] The path-providing guide can include coaxially arranged tubular elements and a tendon connected to one of the tubular elements, and the simultaneous and independent control can include one or more of: controlling the relative axial alignment of the tubular elements, controlling the relative lateral alignment of the tubular elements, controlling the relative rotational alignment of the tubular elements, and controlling the travel of the tendon.

[0046] These and other aspects, features, and advantages of the claimed invention (or inventions) will become apparent from the following detailed written description of the preferred embodiments and aspects thereof, taken in conjunction with the accompanying drawings, although alterations and modifications can be made by those having ordinary skill in the art without departing from the spirit and scope of the novel concepts disclosed herein. BRIEF DESCRIPTION OF DRAWINGS

[0047] Embodiments, features, and aspects of the disclosed technology are described in detail herein and are considered a part of the disclosed technology for which protection is sought. Other embodiments, features, and aspects can be appreciated from the following detailed description, the accompanying drawings, and the claims. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like elements. Reference will now be made to the drawings and flow charts, which are not necessarily drawn to scale.

[0048] Figure 1 is a block diagram of an illustrative computer system architecture 100 in accordance with an example embodiment.

[0049] Figure 2 is a schematic diagram of the present invention in accordance with an example embodiment showing various tubular elements and actuation modules for controlling the tendon and coaxial tubular elements.

[0050] Figure 3 is a schematic diagram showing various segments and parts of a guide providing a path in accordance with an example embodiment.

[0051] Figure 4A shows that variable curvature is allowed by controlling tendon stroke X1 and joint length X2. Figure 4B shows that following leader motion is allowed by controlling X1 and X2 while advancing actuation module X4. Figure 4C shows that outer tubular element X3 is independently advanced to further enter the target vasculature while maintaining the curvature at the location of the vessel tortuosity.

[0052] Figure 5A shows coaxial tube and dimensions in accordance with an example embodiment. Figure 5B shows actuation stages showing various independent linear motors to control the guidewire in accordance with an example embodiment.

[0053] Figures 6A to 6C demonstrates a demonstration of the present invention in accordance with an example embodiment achieving various curvatures at different arc lengths X2.

[0054] Figure 7 shows a bent joint schematic and notched cross-sectional view in accordance with an example embodiment.

[0055] Figures 8 to 9 shows a straight configuration Figure 8 and coaxial tube structure geometry with curvature ( Figure 9 ).

[0056] Figure 10 is a stress-strain curve graph of a nitinol muscle tendon.

[0057] Figure 11is a plot of the kappa-X1 relationship as described below for several values of X2.

[0058] Figure 12 shows a cross-section of three segments of the present robot, with a schematic of each segment with inertia values shown, according to an exemplary embodiment.

[0059] Figure 13 is a plot showing decoupling estimates kappa tot for various intermediate and outer tube depths, expressed as a percentage of the outer diameter of each tube.

[0060] Figure 14 is a plot showing experimental results for the kappa-F t relationship as described below.

[0061] Figure 15A , 15B , 15C shows three samples of intermediate and outer tubes with different depths, demonstrating different coupling between curved and non-curved segments.

[0062] Figure 16 is a schematic of a control system for the present robot, according to an exemplary embodiment.

[0063] Figure 17A shows the following leader motion of a guidewire relative to a given reference path in free space. Figure 17B shows a demonstration of the following leader motion at δ = 22.2 mm.

[0064] Figure 18A shows a guidewire being advanced to a bifurcation point in a linear path, Figures 18B to 18D shows that the guidewire can proceed along either channel at the bifurcation given X ref . The dots represent the guidewire tip.

[0065] Figures 19A to 19D shows the advancement of the outer tube over the inner tube after having successfully traversed a vascular bifurcation (δ = 17.2 mm). DETAILED DESCRIPTION

[0066] While the preferred exemplary embodiments of the present disclosure have been illustrated and described in detail, it should be obvious that the inventive example embodiments are capable of further modifications. Therefore, not intending to limit the scope of the present disclosure to the details described herein, it should be understood that the present disclosure is capable of other example embodiments and is realized in various ways. Moreover, in describing the preferred exemplary embodiments, specific terminology is employed for the sake of clarity.

[0067] As used in the specification and the appended claims, the singular forms "a," "an" and "the" include plural referents unless the context clearly dictates otherwise.

[0068] In addition, in describing preferred exemplary embodiments, terminology will be used that, for the purpose of clarity, can be considered as being generic to the technical field. Each term is intended to encompass all technical equivalents that operate similarly.

[0069] Ranges can be expressed herein as from "about" or "approximately" one particular value and / or to "about" or "approximately" another particular value. When such ranges are expressed, another exemplary embodiment includes from the one particular value and / or to the other particular value.

[0070] The use of "including," "containing," or "comprising" and variations thereof herein is meant to encompass the items listed thereafter, and equivalents thereof as well as additional items. Unless otherwise indicated, the use of the terms "or" and "and" are intended to mean "and / or," that is, the term "or" is the inclusive, not the exclusive use.

[0071] Reference to a method step using one or more steps does not preclude the presence of additional method steps between or in between intermediate steps. Similarly, it is to be understood that reference to one or more components in a device or system does not preclude the presence of additional components or intervening components between or in between the components identified.

[0072] Aspects of the disclosed technology can be implemented using at least some of the components shown in the computing device architecture 100 of Figure 1 As shown, the computing device architecture includes a central processing unit (CPU) 102, which processes computer instructions, a display interface 104, which serves as a communication interface and provides functionality for presenting video, graphics, images, and text on a display. In certain exemplary implementations of the disclosed technology, the display interface 104 can be directly connected to a local display, such as a touchscreen display associated with a mobile computing device. In another exemplary implementation, the display interface 104 can be configured to provide data, images, and other information to an external / remote display that is not necessarily physically connected to the mobile computing device. For example, a desktop monitor can be used to mirror graphics and other information presented on the mobile computing device. In certain exemplary implementations, the display interface 104 can communicate wirelessly with the external / remote display, e.g., via a Wi-Fi channel or other available network connection interface 112.

[0073] In an example embodiment, network connection interface 112 can be configured as a communication interface and can provide functionality for presenting video, graphics, images, text, other information, or any combination thereof on a display. In one example, the communication interface can include a serial port, a parallel port, a general purpose input and output (GPIO) port, a game port, a universal serial bus (USB), a micro-USB port, a high-definition multimedia (HDMI) port, a video port, an audio port, a Bluetooth port, a near field communication (NFC) port, another similar communication interface, or any combination thereof. In one example, display interface 104 can be operatively coupled to a local display, such as a touchscreen display associated with a mobile device. In another example, display interface 104 can be configured to provide video, graphics, images, text, other information, or any combination thereof for an external / remote display that is not necessarily connected to a mobile computing device. In one example, a desktop monitor can be used to mirror or extend graphical information that can be presented on a mobile device. In another example, display interface 104 can communicate wirelessly with an external / remote display, such as via network connection interface 112, such as a Wi-Fi transceiver.

[0074] Computing device architecture 100 can include a keyboard interface 106 that provides a communication interface to a keyboard. In one example embodiment, computing device architecture 100 can include a presence-sensitive display interface 108 for connecting to a presence-sensitive display 107. According to certain example embodiments of the disclosed technology, presence-sensitive display interface 108 can provide a communication interface to connect to various devices, such as pointing devices, touchscreens, depth cameras, and the like, that can or can not be associated with a display.

[0075] Computing device architecture 100 can be configured to use input devices via one or more of the input / output interfaces (e.g., keyboard interface 106, display interface 104, presence-sensitive display interface 108, network connection interface 112, camera interface 114, sound interface 116, and the like) to allow a user to capture information into computing device architecture 100. Input devices can include a mouse, trackball, joystick, trackpad, touch verified trackpad, presence-sensitive trackpad, presence-sensitive display, scroll wheel, digital camera, digital video camera, webcam, microphone, sensor, smart card, and the like. Additionally, input devices can be integrated with computing device architecture 100 or can be separate devices. For example, input devices can be an accelerometer, a magnetometer, a digital camera, a microphone, and an optical sensor.

[0076] The exemplary embodiment of the computing device architecture 100 can include an antenna interface 110 that provides a communication interface to an antenna, a network connection interface 112 that provides a communication interface to a network. As described above, the display interface 104 can communicate with the network connection interface 112, for example, to provide information for display on a remote display that is not directly connected or attached to the system. In certain embodiments, a camera interface 114 is provided that serves as a communication interface and provides functionality for capturing digital images from a camera. In certain embodiments, a sound interface 116 is provided as a communication interface for converting sound to electrical signals using a microphone and for converting electrical signals to sound using a speaker. According to an exemplary embodiment, a random access memory (RAM) 118 is provided in which computer instructions and data can be stored for processing by the CPU 102 in volatile storage.

[0077] According to an exemplary embodiment, the computing device architecture 100 includes a read only memory (ROM) 120 in which immutable low level system code or data for basic system functions (e.g., basic input and output (I / O), booting, or receiving keystrokes from a keyboard) is stored in non-volatile storage. According to an exemplary embodiment, the computing device architecture 100 includes a storage medium 122 or other suitable type of memory (e.g., RAM, ROM, programmable read only memory (PROM), erasable programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM), magnetic disks, optical disks, floppy disks, hard disks, removable cartridges, flash drives) in which files include an operating system 124, application programs 126 (including, for example, a web browser application, a widget or gadget engine, and / or other application programs as desired), and data files 128 are stored. According to an exemplary embodiment, the computing device architecture 100 includes a power supply 130 that provides appropriate alternating current (AC) or direct current (DC) to power the various components.

[0078] According to an exemplary embodiment, the computing device architecture 100 includes a telephone subsystem 132 that allows the device 100 to send and receive sound over a telephone network. The constituent devices and the CPU 102 communicate with each other over the bus 134.

[0079] According to an exemplary embodiment, CPU 102 has a suitable architecture for functioning as a computer processor. In one arrangement, CPU 102 may include more than one processing unit. RAM 118 is connected to a computer bus 134 to provide fast RAM storage to CPU 102 during the execution of software programs such as operating system applications and device drivers. More specifically, CPU 102 loads computer-executable processing steps from storage medium 122 or other media into fields of RAM 118 to execute software programs. Data may be stored in RAM 118, whereby the data may be accessed by the computer CPU 102 during execution. In one exemplary configuration, computing device architecture 100 includes at least 98 MB of RAM and at least 256 MB of flash memory.

[0080] Storage medium 122 itself may include multiple physical drive units, such as a redundant array of independent disks (RAID), a floppy disk drive, flash memory, a USB flash drive, an external hard disk drive, a thumb drive, a pen drive, a key drive, a high-density digital versatile disc (HD-DVD) optical disc drive, an internal hard disk drive, a Blu-ray disc drive or a holographic digital data storage (HDDS) optical disc drive, an external micro dual in-line memory module (DIMM) synchronous dynamic random access memory (SDRAM), or an external micro DIMM SDRAM. This computer-readable storage medium allows a computing device to access computer-executable processing steps, applications, etc., stored on removable and non-removable storage media to offload data from or upload data to the computing device. Computer program products (e.g., computer program products using communication systems) may be tangibly included in storage medium 122, which may include machine-readable storage media.

[0081] According to one exemplary implementation, the term computing device, as used herein, may be a CPU, or conceptualized as a CPU (e.g., Figure 1 (CPU 102). In this exemplary embodiment, the CPU may be coupled, connected, and / or communicate with one or more peripheral devices (e.g., a display). In another exemplary embodiment, the term computing device, as used herein, may refer to a mobile computing device, such as a smartphone, tablet computer, or smartwatch. In this exemplary embodiment, the computing device may output content to its local display and / or one or more speakers. In another exemplary embodiment, the computing device may output content to an external display device (e.g., via Wi-Fi), such as a TV or an external computing system.

[0082] like Figures 2-3As shown, the robotic steerable guidewire system 200 can include a path-providing guide 210 including a proximal portion 212 and a distal portion 214 configured to position a distal end of a guidewire to a destination. The path-providing guide 210 has an operational length, which can be described hereinafter as a combined length of consecutive segment lengths of a segment A (SA), a segment B (SB), and a segment C (SC). The operational length of the path-providing guide 210 can also be described as a combined length of consecutive segment lengths of a non-bent portion (NBP) and a bent portion (BP).

[0083] The control unit / actuation module 300 is operatively connected to the path-providing guide 210. The path-providing guide 210 and the control unit 300 are cooperatively configured to simultaneously and independently control (i) the curvature K of the distal portion BP of the path-providing guide 210, and (ii) the available bent length SA of the distal portion BP of the path-providing guide 210.

[0084] The path-providing guide 210 includes coaxially arranged tubular elements 220 and a tendon 222 connected to one of the tubular elements. As used herein, "coaxial" and / or "coaxially aligned" are relative terms and do not require idealized perfect axial alignment of elements. The present invention is viable for a range of alignments that facilitate telescoping capability, including "nested" arrangements of the tubular elements.

[0085] The skilled person will also appreciate that the term "stiffness" and / or terms having the quality of stiffness can also be described using other relative terms, such as "compliant" and / or terms having the quality of compliance. These relative terms can describe components of the present invention from different directions, e.g., a component or a portion of a component has increasing stiffness along a length, or has decreasing compliance. Or more compliant means less stiff.

[0086] The control unit 300 is configured to control (i) the relative axial alignment of the tubular elements 220, and / or (ii) how one tubular element is centred within another tubular element, and / or (iii) the relative lateral alignment of the tubular elements 220, and / or (iv) the telescoping arrangement or lateral displacement of one tubular element relative to another tubular element, and / or (v) the relative rotational alignment of the tubular elements 220, and / or (vi) the travel of the tendon 222.

[0087] Control of the relative axial alignment of the tubular elements 220 depends on the fit of one tubular element within the other. For example, if the tolerance between the outer wall of the innermost tubular element and the inner wall of the abutting tubular element is negligible, then the amount by which the innermost tubular element is "off-center" can be negligible. Alternatively, if there is a difference between the diameters of the tubular elements (the cross-sections should be identically ovoid), then the greater the tolerance of the relative axial alignment of the tubular elements from the common axis of rotation.

[0088] Control of the relative lateral alignment of the tubular elements 220 is less dependent on the above-described tolerances. As long as one tubular element can "slide" relative to the other, then the length by which one tubular element can extend or retract relative to the other is fairly easily controlled.

[0089] Control of the relative rotational alignment of the tubular elements 220 enables fine-tuning of the stiffness of the distal portion (or portions) of the pathway-providing guide 210 and enables the guidewire to travel out-of-plane (in three dimensions).

[0090] Control of the relative rotational alignment of the tubular elements 220 is relevant when the outer / inner geometry of the tubular elements is not uniform. For example, if the innermost tubular element has a uniform circular cross-section along its length (with a uniform wall thickness and composed entirely of the same material) and if the abutting tubular element has a uniform circular cross-section along its length that is large enough to accommodate the innermost tubular element therethrough and has a uniform wall thickness and is composed entirely of the same material, then the relative rotational alignment between the tubular elements is not affected by the rotation of either tubular element. The rotational condition between them is effectively bland.

[0091] However, if one tubular element has a set of features that do not have rotational symmetry, then how much one tubular element is rotated relative to the other will affect the relationship between the tubular elements.

[0092] In an exemplary embodiment, at least one tubular element 220 has a stiffness feature that enables the stiffness of the proximal portion NBP of the pathway-providing guide 210 to be greater than the stiffness of the distal portion BP of the pathway-providing guide 220.

[0093] The tubular elements 220 can include an inner tubular element 224 having an inner channel, an intermediate tubular element 226 having a stiffness feature 232 along at least a portion of the length of the intermediate tubular element 226, and an outer tubular element 228 having a stiffness feature along at least a portion of the length of the outer tubular element 228.

[0094] Tubular elements 224, 226, 228 each have suitable cross-sectional dimensions such that a guidewire can be rotationally and laterally displaced within the inner passageway of inner tubular element 224, such that inner tubular element 224 can be rotationally and laterally displaced within intermediate tubular element 226, and such that intermediate tubular element 226 can be rotationally and laterally displaced within outer tubular element 228.

[0095] Intermediate tubular element 226 has a length defined from a proximal end to a distal end, and stiffness feature 232 can include a set of notches 242 extending from a proximal end of intermediate tubular element 226 (SB) to a distal end of intermediate tubular element 226 (SA).

[0096] Outer tubular element 228 has a length defined from a proximal end to a distal end, and stiffness feature 234 can include a set of notches 244 extending from a proximal end of outer tubular element 228 (SC) to a distal end of outer tubular element 228 (SA).

[0097] As shown, the length of the set of notches 244 of outer tubular element 228 is greater than the length of the set of notches 242 of intermediate tubular element 226, although the length of one or more sets of notches can vary.

[0098] The set of notches 244 of outer tubular element 228 preferably has a phase difference from the set of notches 242 of intermediate tubular element 226 such that intermediate tubular element 226 is operably rotationally and laterally displaceable within / out of outer tubular element 228. The phase difference of the sets of notches is preferably, but not necessarily, 180°.

[0099] Either or both sets of notches 242, 244 can form a variety of notch geometries / patterns, for example, unidirectional asymmetric notch joints of intermediate tubular element 226 and outer tubular element 228 can be formed.

[0100] By controlling tendon 222, the telescoping of tubular elements 224, 226, 228, the relative rotational alignment of stiffness features 232, 234, and the overall displacement of system 200 define the reach of the guidewire and the ability to navigate an arcuate path of the guidewire (e.g., vasculature). System 200 generally embodies the serpentine ability of the present invention by varying the stiffness of portions of guide 210 providing the path.

[0101] Those skilled in the art will appreciate that the present invention can include more than one tendon and more than three tubular elements, which additional components can expand the reach and ability to follow tortuous paths.

[0102] Furthermore, the skilled person will appreciate that the tubular elements can all have similar cross-sectional profiles to each other or some or all of the tubular elements can have cross-sectional profiles that are similar to each other, indeed even a single tubular element need not have a uniform cross-section along its length. Where the tubular elements have cross-sectional shapes that vary from each other and where there is a variation in cross-sectional shape and / or size over the length of a single tubular element, the tubular elements can slide within / over each other and rotate inside or outside each other.

[0103] The stiffness of the portion SC of the path-providing guide 210 is greater than the stiffness of the portion SB of the path-providing guide 210. The stiffness of the portion SB of the path-providing guide 210 is greater than the stiffness of the portion SA of the path-providing guide 210.

[0104] The stiffness of each portion of the path-providing guide 210 can be controlled by the relative axial alignment of the tubular elements 220, the relative lateral alignment of the tubular elements 220, the relative rotational alignment of the tubular elements 226, 228 and the travel of the tendon 222, such that the portion SC of the path-providing guide 210 is a length segment of the path-providing guide comprising a first portion of the inner tubular element 224, a first portion of the intermediate tubular element 226 (which is free of the set of notches) and a first portion of the outer tubular element 228 (which is provided with the set of notches 244) arranged coaxially.

[0105] The portion SB of the path-providing guide 210 is a length segment of the path-providing guide 210 comprising a second portion of the inner tubular element 224, a second portion of the intermediate tubular element 226 (which is provided with the set of notches 242) and a second portion of the outer tubular element 228 (which is provided with the set of notches 244) arranged coaxially, wherein the first and second portions of the inner tubular element 224 constitute the full length of the inner tubular element 224.

[0106] The portion BP of the path-providing guide 210 is a length segment of the path-providing guide 210 comprising a third portion of the intermediate tubular element 226 (which is provided with the set of notches 242) and a third portion of the outer tubular element 228 (which is provided with the set of notches 244) arranged coaxially.

[0107] The coaxial tubular elements 220 enable the present invention to achieve a "follow-the-leader" motion with limited degrees of freedom (DOF) in the compact space required for a guidewire. In an exemplary embodiment, the inner tubular element 224 is made of stainless steel and has a regular cylindrical cross-section with an internal channel. In an exemplary embodiment, the intermediate tubular element 226 and the outer tubular element 228 are nitinol tubes provided with a micro-machined notch pattern along at least a portion of the length of each tube.

[0108] Each of the tubular elements has a suitable size such that they can slide within each other respectively. To avoid collision / interference between the notches on the intermediate and outer tubular elements, there is a 180° phase difference between the notches. The tendon 222 passes through the inner tubular element 224 and is connected to the distal end of the intermediate tubular element 226.

[0109] Depending on the relative position of each tubular element and the notch pattern, in SA, the notch pattern on the intermediate tubular element reduces its second moment of area and moves its neutral axis to the side without notches, which increases the segment's compliance and tendon force arm. However, in SB, the introduction of the stainless steel inner tubular element increases the combined structure's second moment of area, resulting in a significant increase in the segment's stiffness and a decrease in the force arm. Finally, only the outer tubular element 228 maintains its notch pattern in SC, which helps to increase the segment's stiffness.

[0110] Thus, the present invention as shown has three segments with varying stiffness and can be primarily divided into a bending portion BP (i.e., SA) and a non-bending portion NBP (i.e., SB and SC) depending on the relative position of the inner tubular element 224.

[0111] Reference Figure 2 The control unit / actuation module 300 drives the guide 210 that provides the path. The tendon 222 and the inner and outer tubular elements 224, 228 are connected to drivers 302, 304, 312 respectively. In an exemplary embodiment, these drivers are linear motors.

[0112] Those skilled in the art will appreciate that for particular modes of use, not only the motors, but all elements of the present invention can be selected. For example, if the present invention is to be used in a magnetic resonance imaging (MRI) environment, the motors, tubular elements, and tendons should avoid using those materials that are harmful in an MRI environment.

[0113] The adaptability of the present invention is further enhanced with the selection of the types of components selected. While linear motors can be used, many other displacement mechanisms can be used, including piezoelectric motors and rack and pinion gears. Further, while stainless steel can be used for the inner tubular element, other materials can be used to provide the present invention with the beneficial flexibility / stiffness disclosed herein. Further, while nitinol can be used for the intermediate and outer tubular elements, other materials are known that have sufficient elasticity but still have rigidity to embody the stiffness features such as notches.

[0114] The intermediate tubular element 226 can be fixed to the control unit / actuation module 300 itself or rotatably driven by a driver 308 / gear 314 assembly that can impart rotation to the intermediate tubular element 226. It will be appreciated by those skilled in the art that the operative consideration is the relative rotation of the intermediate tubular element 226 and the outer tubular element 228. Thus, in alternative arrangements, the outer tubular element 228 can be rotated with control of the intermediate tubular element 226 having a fixed rotation, or both elements 226, 228 can have rotational control.

[0115] As shown, the actuation module has five control variables: X1, X2, X3, X4, and ψ, which correspond to the tendon stroke, the relative distance between the inner tubular element and the tubular element, the displacement of the outer tubular element, the displacement of the actuation module, and the rotation of the intermediate tubular element, respectively.

[0116] Given the control variables, the present invention can form any arc shape within the geometric constraints, as X1 and X2 control the curvature and arc length, respectively, of the distal portion of the guide 210 (curved segment A) that provides the path (see Figure 4A ). Thus, by controlling X1 and X2 and by feeding the actuation module X4, the curved segment A can follow the tortuous path of the vasculature, which is a function of the curvature and arc length, which results in the follower motion following the leader during guidance along the curved path (see Figure 4B ).

[0117] The outer tubular element 228 can slide along the curved intermediate tubular element 226 and further travel (see Figure 4C ). The intermediate tubular element 226 can provide a stable passage for the outer tubular element 228 as a guide sheath to reach the appropriate position while maintaining the curvature at the location of the curved path. The entire process can then be repeated at the next curved path until the final target position is reached. Thus, the present invention provides easy insertion of the guidewire in the tortuous vasculature without the need to change the guidewire, thereby significantly reducing the surgery time.

[0118] A prototype of the present invention is shown in Figure 5BThe intermediate tubular element 226 and the outer tubular element 228 were manufactured using super-elastic Nitinol so as to have high bending capabilities, their notched patterns were manufactured on a femtosecond laser (WS-Flex Ultra-Short Pulse Laser Workstation, Optec, Neraemere, Belgium). The tendons 222 were also made of Nitinol so as to be easily inserted through the tubular elements and easily attached. Finally, the inner tubular element 224 was stainless steel because it has higher stiffness than the intermediate and outer tubular elements. The outer tubular element 228, the inner tubular element 224 and the tendons 222 were connected to a linear motor (Maxon Precision Motors, Massachusetts, USA, resolution ~ 2.8 pm) and generated linear motion sliding on each surface (see Figure 5B ). During the motion stroke, the tendon displacement X1 and the arc length X2 of the SA can be controlled so as to achieve variable curvature at several arc lengths of the SA (see Figure 6A , 6B , 6C). The whole actuation platform 300 was mounted on a base with linear guides and driven by a base linear motor 306 (to control X4). The tendons 222 were connected to micro force sensors to measure the tendon tension. The dimensions of the tubular elements as shown in Figure 5A were used in the prototype machine are summarized in Table I.

[0119] Table I

[0120]

[0121]

[0122] In the tested embodiment, the system was manufactured with a shorter length (lo) than the conventional guidewire used for in-vitro feasibility tests.

[0123] To derive the relationship between the tendon stroke X1, the required curvature K and the arc length X2 of the SA and to derive the statics model of the curved part BP and the coupling model in the non-curved part NBPs of the guidewire, the case of a single notched tubular element (“tube”) with a notch depth d, a notch width h and n notches in the joint was considered (see Figure 7 ). Moreover, r o and r i are the outer and inner radii of the tube, respectively, the laser micromachining creates a cross-section of area A o - A i at the notches (see Figure 7 (inset)).

[0124] This cross-section is expressed as the subtraction of the sector area from the sector area where is the central angle produced by the laser micromachining. In order to derive the kinematics of the joint, the expression of the joint's neutral axis must first be obtained. As seen in Figure 7 , the joint's neutral axis is offset from the center axis of the tube along the y-axis due to the notch pattern. For an outer circular sector with area A o , the position of the neutral axis is given as For an inner circular sector with area A i , the position of the neutral axis is given as Finally, the neutral axis of the composite structure (e.g., a notched cross-section with area A o - A i ) is given as follows:

[0125]

[0126] Thus, the position of the neutral axis of the current tube is given as follows (where the subscript "j" refers to the outer tubular element, the intermediate tubular element, or the inner tubular element):

[0127]

[0128] The cross-sectional second moment of the notched segment with area A o - A i is given as follows:

[0129]

[0130] Now, according to the parallel axis theorem and equation (2), the cross-sectional second moment of the notched segment about the neutral axis of the tube is given by:

[0131]

[0132] Given the desired curvature κ and the joint length X2, the required bending angle is given by θ = κX2. In Figure 8 , a schematic of the bending portion of the robot is shown along with the various lengths and radii of the tube. The tendon diameter is denoted as t d . The initial length of the tendon in this straight configuration is given by Here, is the offset between the inner tube and the intermediate notched joint. This is the length at which the joint bending begins and is therefore critical to eliminate any tendon slack at any stage.

[0133] As the wire's bending segment SA is bent to a certain curvature κ, the inner wall of the intermediate tube forms an arc with center "O" and angle θ (see Figure 9 ). As a result, the path of the tendon through the intermediate tube can be split into two parts. In Figure 9 , the two parts are denoted by line segments The straight portion of the indicated rib extends from the inner wall of the inner tube and intersects with the curved portion of the intermediate tube at point 'A', making the line... Point 'A' is tangent to the curved curve.

[0134] exist Figure 9 Central arc The second part, as indicated, bends along with the intermediate tube and travels along the inner wall of the intermediate tube with a radius of r. cur .also, (Derived from equation (2) and abbreviated in the following citation) The notched section of the intermediate tube is located in its central coordinate system. Geometrically, the triangle ΔOAB formed by the straight portions of the tendons is a right triangle, where... also, It is the radius of curvature of the intermediate joint, r t =t d / 2 = 0.038mm is the radius of the cross-section of the tendon bundle.

[0135] The length of the straight portion of the fascia is given as side and The interior angle θ between str Given as θ str =arccos(r cur / r str The length of the curved portion of the fascia is L. cur =r cur (θ-θ str Finally, the required tendon displacements κ and X2 for the target geometry assembly are determined by ΔL. kin (κ,X2)=L i (X2)-(L str +L cur The given information is as follows. Furthermore, the motor stroke X1 height is governed by the tendon elongation for any combination of κ, X2. Therefore, an elongation term is added to the kinematic model as follows:

[0136]

[0137] Here, the applied tendon tension is F. t L total =337.2mm is the original, "unstretched" length of the entire fascia from the robot's end effector to the actuator. E t =53.965 GPa is the Young's modulus of nickel-titanium ribs in its austenitic phase, and it was derived experimentally (see [reference]). Figure 10). To test the used kinematic model, K-X1was evaluated for several joint length X2values (see Figure 11

[0138] For each experiment, the tendon force F t was evaluated and interpreted. The motor stroke data from the encoder was used as ground truth for each case. Finally, for each case, also the kinematic term AL kin In each case, the tendon elongation dominated the joint kinematics. Moreover, equation (5) correctly predicted the joint kinematics, especially for higher values of X2( Figure 11 X2={37.45 mm, 32.45 mm, 27.45 mm} in RMSE = 0.0324 mm). The deviation of the model was higher for lower X2values Figure 11 X2= 17.45 mm, RMSE = 0.1331 mm) which was attributed to higher friction losses when the joint stiffens as the joint length decreases.

[0139] Ideally, the design goal is that the tendon stroke X1would result in the curved segment A (see Figures 2 to 3 in SA) to develop a curvature K, while the non-curved segments B, C (see Figures 2 to 3 in SB and SC) would not undergo any deformation. However, due to the arrangement of the coaxial tubes within the non-curved segments and the coupling between the segments, these segments also undergo a small amount of deformation.

[0140] A statics model for SA and a coupling model related to the coupling effects of the joint recess depth and the non-curved segments were developed and validated. SA (see Figure 12 in the inset) is composed of a recessed middle tube and a recessed outer tube and is driven by a tendon placed along the inner wall of the middle tube. Since the tendon is connected to the distal end of the middle tube, the moment AM=F t Ay n is applied to the whole structure. Here, the force arm Ay n is the displacement between the neutral axis of the tendon and the middle tube in segment n (see Figure 12 in SA, SB, SC). Moreover, due to the actuation of the tendon, the middle tube is displaced and contacts the outer tube (see Figure 12 in the cross-section of SB). The force arm of the tendon force The bending of any recessed tube (recessed middle tube or recessed outer tube) is considered to occur due to the accumulation of the individual curved segments at each recess along the tube.

[0141] ​Since the number of notches in each joint is high (n = {95, 160} for the mid- and outer tube, respectively), the curvature achieved by the bending elements is considered negligible for the individual notched elements of the tubes (≤ 2° for a 180° bend in the joint). Furthermore, it is assumed that the total bending angle is evenly distributed among all notches, while the segment of length c between two notches (see Figure 7 ) does not undergo any bending.

[0142] The uniform notch spacing β = h / (h + c) within a segment is defined as the ratio of the width of an individual notch to the sum of the individual notched and unnotched segments of the joint. For a particular joint segment, the notched and unnotched segments are repeated evenly. Note that the mid- and outer tube are designed with the same value of c. By applying the Euler beam equation for the κ-F t relationship of the SA, the following is obtained:

[0143]

[0144] Since the two tubes are not bonded together and can slide on top of each other, a curvature κ results due to the sum of the inertia terms in the above equation. In equation (6), the second moment of area I is defined in equation (4) for j = {out, mid}. For the SB, the tendon is no longer located at the inner wall of the mid-tube but inside the inner tube (as shown in the cross-sectional view in Figure 12 ). This reduces the force arm of the applied tendon tension to

[0145] Furthermore, the addition of the inner tube in the SB adds an inertia term in the static model (see Figure 12 ):

[0146]

[0147] The inner tube is made of 304 stainless steel and therefore E inn = 200 GPa from the manufacturer's data sheet is assumed. Furthermore, the inner tube is not notched and therefore from equation (4) it follows that Since the tendon tension F t remains constant over the entire length of the robot, the value F t from equation (6) can be substituted into equation (7) to obtain the following coupling ratio between the curvatures (i.e., κ and κ s2 ) of the SA, SB:

[0148]

[0149] Like SB, SC is composed of all three tubes. However, the main difference is that in this segment, the middle tube does not have notches (see Figure 12 ). The force arm of the applied tendon tension is reduced to and the coupling relation between SA and SC gives as follows:

[0150]

[0151] Here, is the moment of inertia of the middle tube without notches and is defined in equation (4). It is clear from equations (8) and (9) that the coupling ratio between the bending and non-bending segments depends only on the geometry of the cross-sections of the segments (not on their relative lengths). Therefore, (d mid , d out ) are the only two parameters that can influence the coupling. The sum of the coupling ratios is used as the cost function for the optimization.

[0152] Figure 13 (d mid , d out ) vs. K tot is shown. The parameters (d mid , d out ) are expressed as a percentage of their corresponding outer diameter. As the micro-machined notch depth increases, the degree of coupling between the segments decreases. However, this decoupling is achieved at the expense of the robot’s end-effector stiffness.

[0153] Three samples corresponding to varying values of (d mid , d out ) (see Figure 15A , 15B , 15C) were micro-machined. As expected, the highest coupling was found in ‘G1’( Figure 15A ), and negligible coupling in ‘G2’( Figure 15B ). Joint ‘G1’ is stiff enough for navigating the vasculature but highly coupled, while sample ‘G2’ is very compliant but can only be used in cases where large curvatures are needed and interaction with the vessel wall is minimal. Therefore, joint ‘G3’( Figure 15B ) was selected as the most likely candidate to achieve high curvatures, minimal coupling, and high stiffness.

[0154] Next, the SA statics model (see equation (6)) was verified for sample ‘G3’. The prototype of the present invention was actuated so that the guide wire could achieve several curvatures to obtain the K-F t relation (see Figure 14). First, for various curvatures and arc lengths of SA (X2={37.45mm, 32.45mm, 27.45mm, 22.45mm, 17.45mm}), it is noted that κ-F t the relationship remains unchanged and can be approximated by a linear fit (RMSE=0.064N) for this geometry. By using this linear approximation and equation (6) and knowing the values of , the elastic modulus of the assembly can be estimated to be E=77.3GPa, which falls within the effective values of super-elastic nitinol in the austenite phase.

[0155] From equations (5) and (6), a direct relationship between κ and X1 is derived as follows, given X2:

[0156]

[0157] Therefore, without any force information, κ can be directly controlled by X1.

[0158] Based on equation (10) and the geometric information of the blood vessel G=[δ, θ, a1, a2] T (see Figure 16 ), the variables (i.e., X1, X2, X3, and X4) can be controlled to follow a specific path of the vasculature. It is assumed that G of the vasculature can be identified by using non-invasive imaging observations such as fluoroscopy or MRI, and that the curve has a constant curvature.

[0159] Along the centerline of the blood vessel, the interventional distance s in the form of path variables is input into the kinematics / statics model with G and it generates the reference X ref.n (n=1, 2, 3, and 4) of the nth linear actuator. Then, according to P1, P2, or P3 in s (i.e., Figure 16 ref ref.1 ref.2 ref.3 ref.4 ] T as follows:

[0160]

[0161] Figure 17A 、 17B It is shown that by using the proposed control scheme in free space (here, a1 and a2 are assumed to be 0), the X-Y coordinates of the tip follow a given reference curved path with various curvatures, and the X-Y coordinates are measured by an electromagnetic tracker in a single tracking experiment. The low curvature path error is relatively small (average L 2 ​​​​​Distance = 4.53 mm) ; however, the error significantly increased in high curvature paths (average L 2 Distance = 14.66 mm). It is believed that this occurs mainly due to the coupling of SB and SC, which shifts the coordinates of SA. However, it is important to note that this robot is intended to be actuated in confined spaces and this coupling problem can be compensated in confined spaces such as vasculature.

[0162] To validate the present invention, a 3D printed vascular phantom was used with various paths that replicated pediatric carotid, aortic arch, and aortic bifurcation with a range of curvatures between 0.08 mm -1 and 0.015 mm -1 . The guidewire was fed into a linear channel (s e P1 in equation (11)) and made to have a curvilinear shape with constant curvature to follow a given reference path at the bifurcation (s e P2 in equation (11)). Figures 18A-18D

[0163] When the distal tip of the robot reaches the end of the curved path, the outer tube slides over the curved intermediate tube (s e P3 in equation (11)) and travels further (see Figures 19A-19D ), which can provide a stable passage for the intermediate tube as a guide sheath to reach the next point of operation. The entire process is repeated for the next curved path.

[0164] Thus, the interventional and navigation functions of the guidewire of the present invention were successfully demonstrated at the bifurcation with various curvatures in the vascular phantom. This feature can prevent the kinking and breaking problems of guidewires that are common in current clinical practice without changing the guidewire and provide a stable and fast interventional procedure to treat cardiovascular diseases in a minimally invasive manner.

[0165] The present invention is a coaxially aligned steerable guidewire robot designed using coaxial tubes (three tubes in an exemplary embodiment) and a tendon (one tendon in an exemplary embodiment). Independent control of the curved arc length and curvature allows the robot to follow the vascular curvatures with varying lengths and bending angles using its inherent follower motion.

[0166] The kinematic and static models of the robot were derived and control algorithms based on these models were proposed to control the present invention. The diameter of the robot prototype is compatible with commercial guidewires. The performance of the present invention was evaluated using a vascular phantom in free space. The robot successfully passed through several high curvature vascular structures. The present invention is also capable of navigating through a three-dimensional virtual vasculature with vascular stiffness properties and a pulsatile blood flow system under fluoroscopy guidance.

[0167] ​While certain embodiments of the disclosed technology have been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the disclosed technology is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

[0168] This written description uses examples to disclose certain embodiments of the disclosed technology, including the best mode, and also to enable any person skilled in the art to practice certain embodiments of the disclosed technology, including making and using any devices or systems and performing any incorporated methods. The patent range of certain embodiments of the disclosed technology is defined by the claims, and can include other examples that occur to those skilled in the art. Such other examples are intended to fall within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent struc tural elements with insubstantial differences from the literal language of the claims.

Claims

1. A steerable guidewire system, comprising: a path-providing guide comprising: a coaxially arranged tubular elements comprising: an inner tubular element having an inner channel; an intermediate tubular element having a set of notches along at least a portion of a length of the intermediate tubular element; and an outer tubular element having a set of notches along at least a portion of a length of the outer tubular element, the set of notches of the outer tubular element having a phase difference from the set of notches of the intermediate tubular element, such that the intermediate tubular element is operably rotatably and laterally displaceable within the outer tubular element; a tendon routed through the inner channel of the inner tubular element of the coaxially arranged tubular elements and attached to a distal end of the intermediate tubular element of the coaxially arranged tubular elements; a proximal portion of the path-providing guide comprising a length segment of a first portion of the inner tubular element, a first portion of the intermediate tubular element free of the set of notches, and a first portion of the outer tubular element having the set of notches coaxially arranged; an intermediate portion of the path-providing guide comprising a length segment of a second portion of the inner tubular element, a second portion of the intermediate tubular element having the set of notches, and a second portion of the outer tubular element having the set of notches coaxially arranged, wherein the first and second portions of the inner tubular element constitute a full length of the inner tubular element; and a distal portion of the path-providing guide comprising a length segment of a third portion of the intermediate tubular element having the set of notches and a third portion of the outer tubular element having the set of notches coaxially arranged, wherein the path-providing guide is configured to position a distal end of a guidewire to a destination; and a control unit operably connected to the path-providing guide; wherein the path-providing guide and the control unit are cooperatively configured to simultaneously and independently control both: a curvature of the distal portion of the path-providing guide via activation of the tendon; and an arc length of the distal portion of the path-providing guide via relative positions of the inner tubular element in lateral displacement of the coaxially arranged tubular elements; and wherein a stiffness of each portion of the path-providing guide is controllable by relative axial alignment of the coaxially arranged tubular elements, relative lateral alignment of the coaxially arranged tubular elements, relative rotational alignment of the coaxially arranged tubular elements, and a stroke of the tendon.

2. The steerable guidewire system of claim 1, wherein, the control unit is a manually operable control unit or an automated control unit; and wherein the steerable guidewire system is a manually steerable guidewire system with the manually operable control unit or a robotic steerable guidewire system with the automated control unit.

3. The steerable guidewire system of claim 1 or 2, wherein: The control unit is configured to one or more of: control the relative axial alignment of the coaxially arranged tubular elements; control the relative lateral alignment of the coaxially arranged tubular elements; control the relative rotational alignment of the coaxially arranged tubular elements; and control the stroke of the tendon. The path-providing guide has a variable stiffness profile along a length of the path-providing guide.

4. The steerable guidewire system of claim 1 or 2, wherein, The variable stiffness profile varies continuously along the length of the path-providing guide.

5. The steerable guidewire system of claim 4, wherein, The variable stiffness profile varies discretely along the length of the path-providing guide; and 6. The steerable guidewire system of claim 4, wherein, wherein along one or more portions of the path-providing guide, the one or more portions have a same stiffness along a length of the one or more portions.

7. The steerable guidewire system of claim 1, wherein: the steerable guidewire system is a robotically steerable guidewire system; and the control unit is configured to one or more of: control the relative axial alignment of the coaxially arranged tubular elements; control the relative lateral alignment of the coaxially arranged tubular elements; control the relative rotational alignment of the coaxially arranged tubular elements; and control the stroke of the tendon.

8. The steerable guidewire system of claim 1 or 2, wherein: the inner tubular element, the intermediate tubular element, and the outer tubular element each have a suitable cross-sectional dimension such that: a guidewire is rotatably and laterally displaceable within the inner passageway of the inner tubular element; the inner tubular element is rotatably and laterally displaceable within the intermediate tubular element; and the intermediate tubular element is rotatably and laterally displaceable within the outer tubular element. the intermediate tubular element has a length defined from a proximal end to a distal end, and the set of notches of the intermediate tubular element begin at an intermediate position of the intermediate tubular element and extend to a distal end of the intermediate tubular element; wherein the outer tubular element has a length defined from a proximal end to a distal end, and the set of notches of the outer tubular element begin at an intermediate position of the outer tubular element and extend to a distal end of the outer tubular element.

9. The steerable guidewire system of claim 1 or 2, wherein, the set of notches of the outer tubular element and the set of notches of the intermediate tubular element form a one-way asymmetric notch joint of the intermediate tubular element and the outer tubular element; and wherein a phase difference between the set of notches of the outer tubular element and the set of notches of the intermediate tubular element is 180°.

10. The steerable guidewire system of claim 1 or 2, wherein, 11. The steerable guidewire system of claim 1 or 2, wherein: a stiffness of the proximal portion of the path-providing guide is greater than a stiffness of the intermediate portion of the path-providing guide; and a stiffness of the intermediate portion of the path-providing guide is greater than a stiffness of the distal portion of the path-providing guide.

12. The steerable guidewire system of claim 1 or 2, wherein: the control unit is a control module operably connected to the path-providing guide; the control module is configured to: ​ ​ laterally displacing the relative position of the inner tubular element with respect to the intermediate tubular element; rotationally displacing the relative position of the intermediate tubular element with respect to the outer tubular element; and laterally displacing the relative position of the outer tubular element with respect to the intermediate tubular element; one or more of the displacements of the inner tubular element, the intermediate tubular element, and the outer tubular element results in a stiffness region along the length of the guide of the provision path, the stiffness of a proximal region being greater than the stiffness of an intermediate region, and the stiffness of the intermediate region being greater than the stiffness of a distal region; and a guidewire is operably configured to pass through the length of the guide of the provision path and be guided to a destination via the variable flexibility and arc length of the intermediate region and the distal region of the guide of the provision path.

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