The disclosed subject matter relates to electrode arrays and systems for inserting same.
Cochlear implants have been a major advent in the field of hearing repair. Cochlear implants have aided patients suffering from severe hearing loss due to damaged neuroepithelial cells of the inner ear. Typically, during cochlear implant surgery, a cochlear implant is placed under the skin in a small dimple carved in the mastoid bone. The implant comprises a receiver and a delicate, highly flexible beam called an electrode array that is inserted into the cochlea. The receiver receives (e.g., from an external microphone with a processor and a transmitter) and delivers the necessary excitation to the auditory nerve via the electrode array. In this way, the electrode array restores some sense of hearing by bypassing damaged neuroepithelial cells (hair cells) in the inner ear and directly providing electrical stimulation to the auditory nerve.
During insertion, the electrode array is usually inserted into the cochlea through a round window into the scala tympani channel. This surgery involves a high level of risk because injuring the basilar membrane can result in complete loss of residual hearing.
The success and applicability of cochlear implants are currently limited by several factors. For example, during cochlear implantation, electrode array insertion is performed “blindly,” without controlling the interaction of the electrode array and cochlear duct. Also, for example, during implantation, the electrode array can buckle (e.g., from impacting the inner ear) and be rendered nonfunctional. Because of the risk, this surgery is typically performed on a limited subset of the population.
In accordance with the disclosed subject matter, electrode arrays and systems for inserting same are disclosed.
In some embodiments, electrode arrays are provided, the electrode arrays comprising: a passive-bending portion; an active-bending portion coupled to the passive bending portion; at least one electrode located in at least one of the passive-bending portion and the active bending portion; and an actuator that causes the active-bending portion to deflect from the passive-bending portion.
In some embodiments, electrode arrays are providing, comprising: means for providing a passive-bending portion; means for providing an active-bending portion coupled to the passive bending portion; means for providing a plurality of electrodes located in at least one of the passive-bending portion and the active bending portion; and means for deflecting the active-bending portion from the passive-bending portion.
In some embodiments, electrode arrays configured for insertion into a cavity are provided, comprising: a body defining a long-axis and having a distal tip; and an actuator for deflecting the distal tip from the long axis.
In some embodiments, systems for inserting an electrode array in the body are provided, the systems comprising: an insertion module for controllably inserting the electrode array in the body and sensing forces applied to the electrode array; a monitor for providing information to a user; and a controller coupled to the insertion module and the monitor, wherein the controller causes the insertion module to control an amount of force that is applied to the electrode array.
In some embodiments, systems for inserting an electrode array in the body are provided, comprising: a means for controllably inserting the electrode array in the body and sensing forces applied to the electrode array; and a means, coupled to the insertion module and the monitor, for causing the means for controllably inserting to control an amount of force that is applied to the electrode array.
The disclosed subject matter will be apparent upon consideration of the following detailed description, taken in conjunction with accompanying drawings, in which:
In accordance with the disclosed subject matter, electrode arrays and systems for inserting same are disclosed.
In some embodiments, an active-bending electrode array can be inserted in the cochlea to restore hearing loss. As described in more detail below, in some embodiments, force can be applied to an actuation thread in the active-bending electrode array creating a deflection in an active-bending electrode array. In some embodiments, magnetic forces may be used to create a deflection in an active-bending electrode array. This deflection can assist the surgeon in implanting an active-bending electrode array in the cochlea and minimize buckling of the electrode array. In some embodiments, a system can be used to insert an electrode array (whether an active-bending electrode array or a passive-bending electrode array) in the cochlea. The system allows a surgeon to visualize the delivery of electrode array into the cochlea. For example, the surgeon can monitor forces applied on an electrode array during insertion to insure that the inner ear is not injured and the electrode array does not buckle.
Referring to
Referring to
As shown, actuation thread 220 is located inside active-bending portion 210 and passive-bending portion 215. Further, actuation thread 220 can attach to active-bending portion 210 at bounded portion 225. Bounded portion 225 can attach actuation thread 220 to active-bending portion 210 using an adhesive (cyanoacrylates, polymer adhesives, etc.) or other means (melting, stitching, etc.). As shown, in some instances, actuation thread 220 can pass through passive-bending portion 215 along centerline 230 and, as actuation thread 220 passes through active-bending portion 210, actuation thread 220 diverges from centerline 230. In some instances, actuation thread 220 can pass through passive-bending portion 215 off of centerline 230. For example, actuation thread 220 can pass through passive-bending portion 215 at some distance away from centerline 215. In some embodiments, actuation thread 220 can pass through passive-bending portion 215 at an angle that is not parallel to centerline 230.
Active-bending portion 210 can deflect (e.g., from its resting configuration) when tension is applied to actuation thread 220. In some instances, passive-bending portion 215 can also deflect when tension is applied to actuation thread 220. For example, tension applied to actuation thread 220 may impart force on active-bending portion 210 causing active-bending portion 210 to deflect. In some embodiments, lessening the tension on actuation thread 220 returns active-bending portion 210 to its resting configuration. As shown in the bottom half of
In some instances, a plurality of electrodes can be located within an active-bending electrode array. Electrodes located in active-bending electrode array 200 can comprise platinum or any other material deemed suitable. In some instances, electrodes located within active-bending electrode array 200 are in a location where they contact the inner ear. For example, the surface of an active-bending electrode array can have holes (e.g., pores, dimples, cut outs, etc.) where electrodes can touch the inner ear of a patient. That is, the electrodes may remain flush with the surface of an active-bending electrode array or they may extend beyond the surface of an active-bending electrode array (e.g., dimple out). In other instances, electrodes located within active-bending electrode array 200 can be in a location where they do not contact the inner ear of a patient. For example, the electrodes can be fully embedded in the active-bending electrode array. The electrodes in electrode array can be electrically coupled to any suitable device, such as device 110 of
In some instances, both active-bending portion 210 and passive-bending portion 215 comprise a substantially similar material. For example, active-bending portion 210 and passive-bending portion 215 can comprise a flexible material (e.g., silicon rubber, plastic, urethane, etc.). In other instances, the properties of active-bending portion 210 and passive-bending portion 215 are substantially different. For example, passive-bending portion 215 can comprise a material that is substantially more rigid than active-bending portion 210. This can be done, for example, to increase the ability to push active-bending electrode array while still allowing a substantial deflection in active-bending portion 210.
In some instances, actuation thread 220 can be a single uniform material. For example, actuation thread 220 can be constructed of a Kevlar thread with a diameter of about 10 μm. In other instances, the properties across the length of actuation thread 220 can vary. That is, actuation thread 220 can have different properties depending on where it is located in an active-bending electrode array. It will be understood that actuation thread 220 can be a substantially solid material exhibiting a uniform cross section (e.g., circular, hollow, square, rectangular, star shaped, etc.). Further, actuation thread 220 can comprise more than one material. For example, actuation thread 220 can be a braid or weave of more than one material. Actuation thread 220 can comprise any suitable material, such as a natural material (cotton, silk, etc.), synthetic material (nylon, Teflon, etc.), metallic material (carbon, NiTi, etc.), or any other suitable material. In some instances, more than one actuation thread can be used in an active-bending electrode array.
In some embodiments, active-bending electrode array 200 can have a substantially consistent shape and can have a substantially smooth outer surface. In some embodiments, variations in the shape and/or the outer surface of active-bending electrode array 200 can change the properties of active-bending electrode array 200. For example, active-bending electrode array 200 can include surface variations (e.g., pits or grooves) or varying thickness (e.g., thinned in the active-bending portion) thereby concentrating stress at a specific location. This concentrated stress can provide enhanced control over angle 205 when force is applied.
In some instances, bonding portion 225 can be located near a distal end of active-bending electrode array 200. Bonding portion 225 alternatively can be located at any other location or set of locations.
In some embodiments, a magnet and a magnetic steering device can be used to create angle 205. For example, a magnetic stylet may be located within array 200, and a magnetic steering device may include controller-controlled electro-magnets. Steering can be accomplished utilizing the intrinsic properties of magnets (e.g., like charges repel, opposite charges attract, etc.). One or more magnets can be located at different locations in an active-bending electrode array. Bonding portion 225 can bond a magnet to an active-bending electrode array. Any material that reacts with a magnet (e.g., ferrous materials) can be used instead of a magnet in suitable circumstances. In some instances, a magnet can be permanently bonded in an active-bending electrode array. In other instances, a magnet can be temporarily bonded in an active-bending electrode array. For example, after an active-bending electrode array is placed in a patient the surgeon can remove the magnet (e.g., by pulling on a thread attached to the magnet).
Referring to
Referring to
In use, insertion module 410 can be placed near the site of entry into the body (e.g., the ear canal, incision point, etc.). In some instances, insertion module 410 can sit on table 430 that is also located near the site of entry into the body. In some embodiments, insertion module 410 may be attached to a patient's head using a stereotactic frame or any other suitable mechanism. Using input device 405, the user can steer insertion module 410 into and inside the body. Insertion module 410 can then advance an electrode array into the body. While advancing, insertion module 410 can receive force and location measurements on the electrode array from sensors in insertion module 410. Force and location measurements can be displayed to the user on monitor 420. If an active-bending electrode array is used, controller 425 can deflect the active-bending electrode array by applying force (e.g., tension on an actuation thread) to the active-bending electrode array. When the electrode array is in a desirable position, insertion module 410 can be removed from the body leaving the electrode array in the body. In some embodiments, the angle of approach and deflection of an electrode array can be controlled by a path-planning module in controller 425, while the depth of insertion can be controlled through input device 405 by the user.
In some embodiments, insertion module 410 can reduce frictional forces on an electrode array by vibrating the electrode array. For example, insertion module 410 can vibrate an electrode array to decrease frictional forces as the electrode array traverses the inner ear. In some instances, vibration in insertion module 410 is a periodic oscillation, aperiodic oscillation, or a combination of both periodic and aperiodic oscillations.
In some instances, vibration can be sensed by at least one sensor in system 400 and a counteractive force created by an at least one actuator located in insertion module 410.
In some embodiments, insertion module 410 can move in many directions. For example, insertion module 410 can have six-axis motion. Six-axis motion in insertion module 410 can be provided by a six-axis miniature parallel system. Further, insertion module 410 can have at least one sensor (e.g., an ATI Nano 17 U-S-3 six-axis force sensor produced by ATI Industrial Automation located in Apex N.C.) for measuring force (e.g., force applied to an electrode array).
In some embodiments, system 400 guides an under-actuated active-bending electrode array. That is, system 400 has fewer actuators than degrees-of-freedom that can be controlled.
In some embodiments, rather than delivering an active-bending electrode array, system 400 delivers a passive-bending electrode array into the body. A passive-bending electrode array deflects when an external force (e.g., impacting tissue in the body) is applied to it.
In some embodiments, system 400 can incorporate a magnetic guidance system. In these embodiments, an active-bending electrode array comprises an active-bending portion, a passive-bending portion, and a magnet or a magnetic material. In some instances, there may be no actuation thread in the active-bending electrode array. A magnetic guidance system can be located external to the body. In some instances, a magnetic guidance system can be attached to insertion module 410. A magnetic guidance system can incorporate electro magnets. When a deflection is desired, the system can apply magnetic force to an active-bending electrode array and produce a deflection similar to that seen when force is applied by an actuation thread. In some instances, a magnet can be attached (e.g., by a thread) to insertion module 410. When desired, insertion module 410 can apply force and remove the magnet from the active-bending electrode array.
In some embodiments, input device 405 can incorporate force feedback. When force is detected on an electrode array (e.g., a force detected by an active-bending electrode array connected to the parallel robot through a small ATI Nano 17 U-S-3 six-axis force sensor) force can be applied by input device 405 (e.g., Sidewinder Force Feedback™ from Microsoft Co., Impulse Stick from Immersion Corporation, etc.) to the user. For example, as force applied to an active-bending electrode array increases, input device 405 can vibrate or provide resistance with increasing strength indicating the situation to the surgeon.
In some embodiments, the surgeon controls the motion of the insertion module in all directions using the input device and relies on information displayed on monitor 420. For example, the surgeon can deliver an electrode array into the body and determine the safety of insertion based on, for example, the insertion force measurements provided on monitor 420 based on force feedback.
In some embodiments, the surgeon controls the insertion module in the axial direction during insertion while a controller 425 steers all other directions. In some instances, the controller, for example, has a preset path-planning module. In some instances, the preset path-planning module is based on, for example, 3D extensions of a 2D template of a cochlea. In some instances, using a path-planning module, the forces on the electrode array are reduced during insertion. In some instances, the surgeon controls the speed of the insertion (e.g., via the input device) while the controller controls the orientation of insertion and the bending of the electrode (e.g., using the insertion module).
In some embodiments, system 400 can perform the insertion automatically while offering the surgeon the possibility to take control. For example, the system may deliver an electrode array by following a path-planning module based on patient data.
In some embodiments, monitor 420 can display the location of the active-bending electrode array in the body (e.g., the inner ear) and can also display a graph of the force being applied to the active-bending electrode array (e.g., as illustrated in
For example, as shown in
Referring to
Referring to
Referring to
It will be understood that monitor 420 can display any form of information (e.g., forces, temperature, time, velocity, acceleration, vibration, etc.) to the surgeon related to an electrode array insertion (e.g. delivering, positioning, etc.).
Referring back to
Controller 450 may be any suitable device or devices for receiving input from and controlling the operation of input device 405, insertion modules 410 and 450, arm 435, table 430, and monitor 420 illustrated in
Turning to
Referring to
Referring to
Referring to
Referring to →
2 describing the backbone of the active-bending electrode array (i.e., the length from s=0 at the base of the active-bending electrode array to s=1 at the tip of the active-bending electrode array).
The active-bending electrode array can be assumed to bend in the plane {{circumflex over (x)}l,{circumflex over (z)}l}. The configuration of an active-bending electrode array can be controlled by qp and qe, where qp designates the joint coordinates of an insertion module holding the active-bending electrode array and qe designates the joint variables of the electrode array. The electrode array coordinates, qe, can be related to the bending angle at the tip of the active-bending electrode array according to qe=f(θ(L)). As shown in equation 2, each point along the backbone of an active-bending electrode array can be given by direct integration along h(s): →
2 while accounting for any location contraction ε(s)<0 due to the actuation forces acting on the body of the active-bending electrode array (e.g., forces acting on the silicon rubber). ε(s) can be computed based on the stiffness properties of an active-bending electrode array and can, for example, be verified experimentally by visually tracking motions of markers along the active-bending electrode array's axis. Matrix wRl can refer to the rotation matrix relating {{circumflex over (x)}l,ŷl,{circumflex over (z)}l} coordinated system to {{circumflex over (x)}w,ŷw,{circumflex over (z)}w} and t(qp) can refer to the position of a stand, where an insertion module is located, with respect to {{circumflex over (x)}w,ŷw,{circumflex over (z)}w}. Using the twist distribution g(θL,s), as in equation 3, one can define the instantaneous kinematics for each point along the backbone of the electrode array as in equation 4. The configuration vector (i.e., the position and orientation of each location coordinate system along the backbone) is defined by x(s)ε
6x1. Jp refers to the instantaneous kinematics Jacobian of an insertion module such that {dot over (q)}p={dot over (j)}p{dot over (x)}p where {dot over (x)}p is the linear and angular velocity of a movable stand. Je refers to the Jacobian of an active-bending electrode array to be derived. The first term of equation 4 represents the kinematics of the insertion module and the second term represents the kinematics of an active-bending electrode array.
{dot over (θ)}(s)=g(θLs){dot over (θ)}(L) (3)
{dot over (x)}(s)=Jp−1{dot over (q)}p+wlJe{dot over (q)}e (4)
Still referring to →
3. Thus, for each insertion depth, d, an error vector can be quantified using equation 7. The distance between the center of the inner ear and the inserted portion of the electrode array is minimized using equation 8. The solution of equation 8 can be achieved using a mathematical optimization technique (e.g., least-squares sense) and will yield the value of the desired actuation variables {tilde over (q)}=[qel,qpl]l.
e(d): p(q)−Pd. (7)
Min{tilde over (q)}(ele) (8)
Additionally or alternatively, a path planning module in accordance with some embodiments may calculate the path of an electrode array as follows. Let sq represent the electrode insertion depth and let θc(s) be the shape of the cochlea. Equation 9 returns the optimal value of q that minimizes the shape difference between the inserted portion of the electrode and the cochlea. The optimal value of q is found by calculating the objective function for all columns of Φ and the minimum is found by numerical interpolation between the columns that best approximate the minimum value of the objective function.
In some embodiments, the distance between the electrode array and the wall of the cochlea can be calculated. The calculated distances between the electrode array and the wall of the cochlea can be used to lessen frictional forces between the electrode array and the cochlea. For example, equation 10 can be used to quantify the performance of an active-bending electrode array. E(θ) refers to the distance between the inserted portion of the electrode array and the wall of the cochlea and θ refers to the angle of the electrode curve tangent to the x-y plane. In some embodiments, equation 10 may be used to determine the optimal routing of an actuation thread.
The insertion force due to friction between the electrode and cochlea may be equivalent to friction force in a band brake system, which depends on the contact angle of the electrode with the external walls of the cochlea. To explain this, third-order polynomials can be fitted to the digitized data to represent the curve of the external wall of the electrode, rc, and the curve of the outer wall of the cochlea, rl. Using these polynomial representations a distance metric e(θ)=∥rc(θ)−rl(θ)∥2 θε[0,φ] can be calculated (where φ is the insertion angle) and averaged for every insertion angle during the insertion as shown in equation (11).
This explains the decrease in the insertion forces when the electrode is actuated since the average distance metric is increased significantly compared to the passive electrode array. Moreover, the difference between the active electrode array and the passive electrode array becomes more prominent as the insertion depth increases.
In some embodiments, the speed of insertion is adjusted to minimize the force of insertion. For example, referring to equation 12, fs refers to the force and ms refers to force and moment measured by a force sensor. {dot over (X)}q refers to the twist (i.e., linear and angular velocity) of the parallel robot at the point where the electrode is supported. {circumflex over (z)}g refers to the tangent to the electrode at the point where the electrode is supported. Scalars that adjust the insertion speed along and perpendicular to the electrode tangent {circumflex over (z)}g are represented by νins and νl. The first term in equation 12 determines the insertion speed while the second term in equation 12 adjusts the velocity to follow the involute of the electrode shape as the insertion forces increase.
{dot over (X)}
g=νins{circumflex over (z)}g+νl((I−{circumflex over (z)}g{circumflex over (z)}gl)fs/∥(I−{circumflex over (z)}g{circumflex over (z)}gl)fs∥2 (12)
The insertion speed (i.e., νins) can be determined by equation 13. Where νmin and νmax are the minimal and maximal tolerable insertion speeds. The parameter t can be determined based on disparity between the measured insertion force intensity fins=fsl{circumflex over (z)}g and the magnitude of the typical insertion forces {tilde over (f)}(θ) for a non-steerable electrode based on a friction model or on experimental results. Equation 14 relies on the assumption that a steerable electrode will be able to follow the shape of the cochlea and to reduce insertion forces. Parameters α and β can be determined experimentally. Parameter β will have an inverse relationship with νins (i.e., as νins decreases as a result of large insertion forces, β will be increased to provide more motion in the direction of the electrode involute).
νins=νmin+tα(νmax−νmin),tε[0,1],αε (13)
t=({tilde over (f)}(θ)=fins/{tilde over (f)}(θ) (14)
In some embodiments, the friction force between the walls of the inner ear (e.g., scala tympani) and the electrode array may be calculated and used to better the design of the electrode array. For example using equation 15 the deflection in an active-bending electrode array may be optimized to minimize frictional forces on an active-bending electrode array. f refers to the total friction force (i.e. insertion force) required. fend refers to any force action on the tip of the electrode array to prevent it from sliding against the walls of the cochlea. fendeuθ refers to the required force to overcome fend acting at the tip of the electrode array. θ refers to the total contact angle between the cochlea and the electrode array. fseuθ refers to the expression for the coulomb friction due to contact pressure generated by the bending rigidity of the electrode array.
f=f
end
e
uθ
+f
s
e
uθ (15)
Other embodiments, extensions, and modifications of the ideas presented above are comprehended and are within the reach of one versed in the art upon reviewing the present disclosure. Accordingly, the scope of the present invention in its various aspects are not be limited by the examples presented above. The individual aspects of the present invention, and the entirety of the invention are to be regarded so as to allow for such design modifications and future developments within the scope of the present disclosure. For example, although specific features are described herein in certain combinations, the present invention may be practiced using any combination of any of all or a subset of these features. The present invention is limited only by the claims that follow.
This application claims the benefit of U.S. Provisional Patent Application No. 60/726,770, filed on Oct. 14, 2005, U.S. Provisional Patent Application No. 60/772,796, filed on Feb. 13, 2006, and U.S. Provisional Patent Application No. 60/781,994, filed on Mar. 13, 2006, which are hereby incorporated by reference herein in their entirety.
Number | Date | Country | |
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60726770 | Oct 2005 | US | |
60772796 | Feb 2006 | US | |
60781994 | Mar 2006 | US |
Number | Date | Country | |
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Parent | 11581899 | Oct 2006 | US |
Child | 13347041 | US |