U.S. patent application number 13/347041 was filed with the patent office on 2012-05-03 for electrode arrays and systems for inserting same.
This patent application is currently assigned to THE TRUSTEES OF COLUMBIA UNIVERSITY IN THE CITY OF NEW YORK. Invention is credited to Spiros Manolidis, Nabil Simaan.
Application Number | 20120109274 13/347041 |
Document ID | / |
Family ID | 38534530 |
Filed Date | 2012-05-03 |
United States Patent
Application |
20120109274 |
Kind Code |
A1 |
Simaan; Nabil ; et
al. |
May 3, 2012 |
ELECTRODE ARRAYS AND SYSTEMS FOR INSERTING SAME
Abstract
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; a plurality of
electrodes 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, 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.
Inventors: |
Simaan; Nabil; (Nashville,
TN) ; Manolidis; Spiros; (New York, NY) |
Assignee: |
THE TRUSTEES OF COLUMBIA UNIVERSITY
IN THE CITY OF NEW YORK
New York
NY
|
Family ID: |
38534530 |
Appl. No.: |
13/347041 |
Filed: |
January 10, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11581899 |
Oct 16, 2006 |
8116886 |
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13347041 |
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60726770 |
Oct 14, 2005 |
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60772796 |
Feb 13, 2006 |
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60781994 |
Mar 13, 2006 |
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Current U.S.
Class: |
607/137 |
Current CPC
Class: |
A61N 1/0541 20130101;
B33Y 80/00 20141201 |
Class at
Publication: |
607/137 |
International
Class: |
A61F 11/04 20060101
A61F011/04; A61N 1/05 20060101 A61N001/05 |
Claims
1-23. (canceled)
24. A steerable electrode array that can be implanted in an inner
ear of a patient, comprising: a passive-bending portion; an
active-bending portion coupled to the passive bending portion,
wherein the passive-bending portion and the active-bending portion
can shape at least partially to an anatomy of in an inner ear of a
patient and are configured for permanent implantation in the inner
ear; a plurality of electrodes located in at least one of the
passive-bending portion and the active bending portion and is
configured to excite auditory nerve in the inner ear by providing
electrical stimulation; and at least one actuation thread located
in the passive-bending portion and the active-bending portion and
configured to cause the active-bending portion to deflect from the
passive-bending portion when tension is applied.
25. The steerable electrode array of claim 24, wherein the
active-bending portion is made of a substantially flexible
material.
26. The steerable electrode array of claim 24, wherein the
passive-bending portion and the active-bending portion are made of
a same material or substantially similar materials.
27. The steerable electrode array of claim 24, wherein the at least
one actuation thread is coupled to the active-bending portion at a
distal end of the active-bending portion.
28. The steerable electrode array of claim 27, wherein the at least
one actuation thread is temporarily bonded to the active-bending
portion.
29. The steerable electrode array of claim 27, wherein the at least
one actuation thread is permanently bonded to the active-bending
portion.
30. The steerable electrode array of claim 24, wherein the at least
one actuation thread is coupled to the active-bending portion at a
plurality of points.
31. The steerable electrode array of claim 24, wherein the at least
one actuation thread is one of a magnet or a ferrous material that
can react with a magnet.
32. The steerable electrode array of claim 24, wherein the at least
one actuation thread is made of a uniform material.
33. The steerable electrode array of claim 24, wherein the at least
one actuation thread is one of a braid or weave that is made of
more than one material, including at least two of cotton, silk,
nylon, Teflon, carbon, and/or nickel titanium.
34. The steerable electrode array of claim 24, wherein the at least
one actuation thread has different properties depending on where in
the electrode array the actuation thread is located.
35. The steerable electrode array of claim 24, wherein the at least
one actuation thread is a substantially solid material exhibiting a
uniform cross section.
36. The steerable electrode array of claim 35, wherein the cross
section can be one of circular cross section, square cross section,
rectangular cross section, star shaped cross section or a hollow
cross section.
37. The steerable electrode array of claim 24, wherein the
plurality of electrodes are in a location where the electrodes
contact the inner ear.
38. The steerable electrode array of claim 37, wherein the
plurality of electrodes remain flush with a surface of the
electrode array.
39. The steerable electrode array of claim 37, wherein the
plurality of electrodes extend beyond a surface of the electrode
array.
40. The steerable electrode array of claim 24, wherein the
plurality of electrodes are in a location where the electrodes do
not contact the inner ear.
41. The steerable electrode array of claim 24, wherein the at least
one actuation thread passes through the passive-bending portion
along the passive-bending portion's centerline.
42. The steerable electrode array of claim 24, wherein the at least
one actuation thread passes through the passive-bending portion off
of the passive-bending portion's centerline.
43. The steerable electrode array of claim 24, wherein the at least
one actuation thread passes through the passive-bending portion at
an angle that is not parallel to the passive-bending portion's
centerline.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] 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.
TECHNOLOGY AREA
[0002] The disclosed subject matter relates to electrode arrays and
systems for inserting same.
BACKGROUND
[0003] 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.
[0004] 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.
[0005] 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.
SUMMARY
[0006] In accordance with the disclosed subject matter, electrode
arrays and systems for inserting same are disclosed.
[0007] 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.
[0008] 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.
[0009] 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.
[0010] 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.
[0011] 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.
DESCRIPTION OF DRAWINGS
[0012] The disclosed subject matter will be apparent upon
consideration of the following detailed description, taken in
conjunction with accompanying drawings, in which:
[0013] FIG. 1 is an anatomical depiction of a human ear and
cochlear implant in accordance with some embodiments of the
disclosed subject matter;
[0014] FIG. 2 is a side, cross-sectional view drawing illustrating
an active-bending electrode array in accordance with some
embodiments of the disclosed subject matter;
[0015] FIG. 3 demonstrates an active-bending electrode array during
various ranges of deflection in accordance with some embodiments of
the disclosed subject matter;
[0016] FIG. 4A is a depiction of a system for inserting an
electrode array in accordance with some embodiments of the
disclosed subject matter;
[0017] FIG. 4B is a depiction of another system for inserting an
electrode array in accordance with some embodiments of the
disclosed subject matter;
[0018] FIGS. 5A-5D are graphs that can be presented during
insertion of an electrode array in accordance with some embodiments
of the disclosed subject matter;
[0019] FIG. 6 is a diagram of a process for controlling systems for
inserting an electrode array in accordance with some embodiments of
the disclosed subject matter;
[0020] FIGS. 7A-7C displays various models of a cochlea in
accordance with some embodiments of the disclosed subject matter;
and
[0021] FIGS. 8 and 9 are images demonstrating some of the
dimensions used to determine various mathematical relationships in
accordance with some embodiments of the disclosed subject
matter.
DETAILED DESCRIPTION
[0022] In accordance with the disclosed subject matter, electrode
arrays and systems for inserting same are disclosed.
[0023] 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.
[0024] Referring to FIG. 1, an anatomical depiction of the human
ear is displayed. It will be apparent that the disclosed subject
matter can be used in other parts of the body (e.g., the lungs,
heart, kidneys, fetus, etc.). For ease of understanding, this
application primarily focuses on electrode arrays implanted in the
inner ear 105. In some instances, a device 110 (e.g., transmitter,
receiver, microphone, or processor) can be implanted under skin in
a dimple carved into the mastoid bone and attached to an electrode
array 115 located in inner ear 105 by a wire connection 120. For
ease of reference, the inner ear shall refer to the cochlea,
vestibule, and semi-circular canals.
[0025] Referring to FIG. 2, two illustrations of an active-bending
electrode array 200 that can be used in various embodiments are
shown. In some instances, active-bending electrode array 200 can
comprise multiple portions, such as an active-bending portion 210
and a passive-bending portion 215. Active-bending electrode array
200 can also comprise an actuation thread 220, a bounding portion
225, and a plurality of electrodes (not shown). The electrodes, for
example, may comprise any suitable number of electrodes and may be
positioned at any suitable location in the electrode array.
[0026] 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.
[0027] 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 FIG. 2,
active-bending electrode array 200 can arc by an angle 205 when
tension is applied to actuation thread 220. This angle 205 can
assist surgeons during surgery, reducing damage to the body (e.g.,
the inner ear), and reducing damage to the active-bending electrode
array (e.g., lessen the chances for buckling).
[0028] 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 FIG. 1.
[0029] 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.
[0030] 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 .mu.m.
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.
[0031] 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.
[0032] 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.
[0033] 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).
[0034] Referring to FIG. 3, in some embodiments, actuation thread
220 (not shown) can allow an active-bending electrode array 200 to
deflect various amounts. As shown, applying tension to actuation
thread 220 (not shown) can create a substantial deflection in
active-bending electrode array 200 as is illustrated by deflections
305, 310, 315 and 317. As shown, in some embodiments, various
angles of deflection 320 may be possible. For example, angles of
deflection 320 may be in excess of 360 degrees in some
embodiments.
[0035] Referring to FIG. 4A, in some embodiments, a system 400 can
be used for inserting an electrode array (e.g., an active-bending
electrode array or a passive-bending electrode array). System 400
can comprise an input device 405, an insertion module 410, a data
connection 415, a controller 425, and a monitor 420. System 400 can
also include a table 430 that allows motion in one or more
directions (e.g., motion in a positive or negative direction along
one or more orthogonal axes). In some embodiments, an arm 435 can
connect insertion module 410 with table 430. In some embodiments,
arm 435 can be robotic.
[0036] 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.
[0037] 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.
[0038] 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.
[0039] 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).
[0040] 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.
[0041] 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.
[0042] 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.
[0043] 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.TM. 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.
[0044] 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.
[0045] 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).
[0046] 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.
[0047] 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 FIGS. 5A
and 5B). In some instances, a single line in the graph can
demonstrate all forces applied to an active-bending electrode
array. In other instances, multiple lines in the graph can display
various forces applied to an active-bending electrode array. For
example, one line in the graph can display external forces (e.g.,
force from contacting the body) applied on an active-bending
electrode array and another line can display the force applied by
an actuation thread.
[0048] For example, as shown in FIG. 5A, in some embodiments,
monitor 420 displays the force applied on a passive-bending
electrode array with respect to insertion distance in the body. For
example, at an insertion displacement (i.e., the distance the
electrode array has been inserted into the body) of 30 mm (e.g., 30
mm from the point of entry into the body) the sensed force on the
passive-bending electrode array is 2.5 grams. In some instances, an
electrode array may buckle. Buckled electrode arrays may be
displayed on monitor 420 as a substantial peak in force and/or flat
line. For example, area 540 indicates a buckled passive-bending
electrode array.
[0049] Referring to FIG. 5B, in some embodiments, monitor 420
displays the force applied on an active-bending electrode array
with respect to the insertion distance in the body. For example, at
an insertion displacement of 50 mm the sensed force on the
active-bending electrode array is 5 grams.
[0050] Referring to FIG. 5C, in some embodiments, monitor 420
displays more than one plot of forces applied on an electrode array
(e.g., active-bending electrode array plot 560 and passive bending
electrode array plot 550). For example, force measurements can be
stored and displayed on monitor 420 thereby aiding a surgeon in
determining if the force on the electrode array is beyond an
acceptable limit. In some instances, force measurements displayed
against insertion distances can be used to determine how to bend an
active-bending electrode array at various insertion depths. For
example, if increased force is observed at a certain depth, this
can indicate to the surgeon that a deflection is required.
[0051] Referring to FIG. 5D, in some embodiments, monitor 420
displays insertion speed of an electrode array with respect to
insertion distance. For example, the insertion speed displayed
against insertion displacement can be for an active-bending
electrode array. As shown, in some embodiments, the insertion speed
may remain substantially constant (e.g., constant region 550). In
other embodiments, the insertion speed may change at various depth
of insertion (e.g., variable region 560).
[0052] 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.).
[0053] Referring back to FIG. 4B, in some embodiments, a surgeon
505 can guide the insertion of an electrode array without using an
insertion module 410 or input device 405. Rather, the surgeon 505
can use an insertion module 450. Like insertion module 410,
insertion module 450 can be used to insert an electrode array into
the cochlea. In some embodiments, insertion module 450 can
compensate for external forces. For example, input module 450 can
compensate for tremors in the surgeon's hand using suitable motion
sensors and actuators. External forces (e.g., tremors in the
surgeon's hands) can be detected by a sensor, a digital processing
device can determine the corrective force needed, and an insertion
module can produce the corrective force to compensate for the
external force. External force compensation can be as simple as,
for example, detecting an external force and applying an equal and
opposite force to counter the external force. However, external
force compensation can be significantly more complex, for example,
analyzing the external force and comparing the force to a range of
allowable forces. If the external force falls outside an acceptable
range of allowable force, the force compensation system can cancel
out the force. Force cancellation can involve not simply a single
equal and opposite force, but, rather, for example, it can require
a series of small forces compensating for the larger external
force.
[0054] 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 FIGS. 4A and 4B. For example, controller 450 may
be a general-purpose computer, including a digital processing
device, with suitable interface cards.
[0055] Turning to FIG. 6, a diagram of a process 600 that can
operate in controller 425 is illustrated. As shown, process 600 can
receive user input at 602. This user input may be provided from
user input device 405 or insertion module 450, and may include hand
movements (whether intentional or unintentional), button
depressions, etc. At 604, process 600 can detect forces applied on
an electrode array. These forces may be detected by insertion
module 410 or 450 as described above. At 608, process 600 can
determine the movement required of insertion module 410 or 450.
This movement can include movement to insert the electrode array,
bend the electrode array, remove insertion module 410, remove hand
tremors from insertion module 450, move arm 435, move table 430 or
any other movement associated with insertion module 410, arm 435,
table 430, and insertion module 450. The movement determined by 608
can include movement calculated by a path-planning module as
described herein. At 610, process 610 may drive the movement of
insertion module 410, arm 435, table 430, and insertion module 450.
The drive signals may be generated by a suitable interface in
controller 450. The force detected at 604 and the movement driven
at 610 can be used to provide an output to monitor 420 at 606. At
606, process 600 can additionally or alternatively generate any
other suitable output to monitor 420 as described herein. At 612,
process 600 may provide feedback to a user, such as by creating
force on a joystick being used by the user, as described above.
Process 600 may then loop back to 602. While the blocks of process
600 are illustrated in FIG. 6 as occurring in a specific order, it
should be apparent to one of skill in the art that these blocks may
occur in any suitable order or in parallel.
[0056] Referring to FIG. 7A, in some embodiments, a 3D model can be
used to simulate surgery. For example, as displayed, a computer
model 700 of a cochlea can be produced using Computer-Aided Design
(CAD) tools. Using stereo-lithography, computer model 700 can be
used to create a prototype model 705 of a cochlea. Further, the
prototype model can be used to create a 3D model for performing
simulated surgery (e.g., practicing using a system for inserting an
active-bending electrode array).
[0057] Referring to FIG. 7B, in some embodiments, an electrode
array (i.e., an active-bending electrode array 200 or a
passive-bending electrode array 720) may be delivered into a
cochlea model 710 (e.g., delivered into cochlea model 710 at an
insertion point 750). For example, cochlea model 710 can be used to
facilitate teaching doctors how to deliver active-bending electrode
array 200 and passive-bending electrode array 720 into a cochlea.
Experiments performed on cochlea models can, for example, establish
better deflections for active-bending electrodes and help to
eliminate frictional forces applied to an electrode array during
delivery. It will be understood that frictional forces applied to
an electrode array may buckle the electrode array. For example, as
shown in slides I-V, passive-bending electrode array 720 can be
inserted into cochlea model 710, however, prior to completing the
first 180 degrees, passive-bending electrode array 720 buckles as
shown in area 725. Referring to steps VI-X active-bending electrode
array 200 enters into cochlea model 710 and completes the first 180
degrees without buckling. Referring to step IX, active-bending
electrode array 200 creates a deflection 740. In some embodiments,
deflection 740 allows active-bending electrode array 200 to be
delivered into a cochlea without buckling. In some embodiments, a
cochlea model may be placed in a human skull model. For example,
this may be done to provide the surgeon with a more realistic
training environment.
[0058] Referring to FIG. 7C, in some embodiments, an active-bending
electrode array can shape (e.g., curve, bend, etc.) at least
partially to the anatomy of the cochlea. For example, the shape of
the cochlea can be displayed as a cochlea curve 730, the shape of
an active-bending electrode array delivered into the cochlea can be
displayed as an active-bending electrode array curve 735, and the
shape of a passive-bending electrode array delivered into the
cochlea can be displayed as a passive-bending electrode array curve
740. As shown, for example, active-bending electrode array curve
735 more accurately adheres to cochlea curve 730 than
passive-bending electrode array curve 740. In some embodiments, for
example, an active-bending electrode array delivered into the
cochlea more accurately follows the curvature of the cochlea and
generates less frictional forces than a passive-bending electrode
array. In some embodiments, the active-bending electrode array more
accurately adheres to the curvature of a cochlea than a
passive-bending electrode array because, for example, the
active-bending electrode array can create an deflection.
[0059] Referring to FIGS. 8 and 9, in some embodiments, an
active-bending electrode array can be modeled kinematically. For
example, let {{circumflex over (x)}.sub.w,y.sub.w,{circumflex over
(z)}.sub.w} refer to the world coordinate system, and {{circumflex
over (x)}.sub.l,y.sub.l,{circumflex over (z)}.sub.l} refer to the
coordinate system characterizing the plane in which the
active-bending electrode array deflects. Also, let {{circumflex
over (x)}.sub.p,y.sub.p,{circumflex over (z)}.sub.p} refer to a
coordinate system attached to a moving stand where an insertion
module is located. Coordinate system {{circumflex over
(x)}.sub.e,y.sub.e,{circumflex over (z)}.sub.e} is defined as being
attached at the tip of an active-bending electrode array and
aligned such that {circumflex over (x)}.sub.e lies in {{circumflex
over (x)}.sub.l,{circumflex over (z)}.sub.l} plane and {circumflex
over (z)}.sub.e is the tangent to the active-bending electrode
array at its tip. The shape of the active-bending electrode array
can be characterized using the mathematical representation shown in
equation 1, where .theta. refers to the angle of the curve tangent
in the {{circumflex over (x)}.sub.l,{circumflex over (z)}.sub.l}
plane and s refers to the arc-length parameter along the curve
h(s): .fwdarw..sup.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).
.theta. ( s ) = i = 1 n a n .PHI. n ( s ) = a t .PHI. ( s ) ( 1 )
##EQU00001##
[0060] The active-bending electrode array can be assumed to bend in
the plane {{circumflex over (x)}.sub.l,{circumflex over
(z)}.sub.l}. The configuration of an active-bending electrode array
can be controlled by q.sub.p and q.sub.e, where q.sub.p designates
the joint coordinates of an insertion module holding the
active-bending electrode array and q.sub.e designates the joint
variables of the electrode array. The electrode array coordinates,
q.sub.e, can be related to the bending angle at the tip of the
active-bending electrode array according to q.sub.e=f(.theta.(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): .fwdarw..sup.2 while accounting for any location
contraction .epsilon.(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). .epsilon.(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 .sup.wR.sub.l can refer to the rotation matrix relating
{{circumflex over (x)}.sub.l,y.sub.l,{circumflex over (z)}.sub.l}
coordinated system to {{circumflex over
(x)}.sub.w,y.sub.w,{circumflex over (z)}.sub.w} and t(q.sub.p) can
refer to the position of a stand, where an insertion module is
located, with respect to {{circumflex over
(x)}.sub.w,y.sub.w,{circumflex over (z)}.sub.w}. Using the twist
distribution g(.theta..sub.L,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).epsilon..sup.6x1.
J.sub.p refers to the instantaneous kinematics Jacobian of an
insertion module such that {dot over (q)}.sub.p={dot over
(j)}.sub.p{dot over (x)}.sub.p where {dot over (x)}.sub.p is the
linear and angular velocity of a movable stand. J.sub.e 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.
r ( s ) = R 1 w .intg. 0 e ( ( 1 + ( .tau. ) ) [ cos ( a t .PHI. (
.tau. ) 0 sin ( a t .PHI. ( .tau. ) ] ) .tau. + t ( q p ) ( 2 )
##EQU00002## {dot over (.theta.)}(s)=g(.theta..sub.Ls){dot over
(.theta.)}(L) (3)
{dot over (x)}(s)=J.sub.p.sup.-1{dot over
(q)}.sub.p+.sup.w.sub.lJ.sub.e{dot over (q)}.sub.e (4)
[0061] Still referring to FIGS. 7 and 8, in some embodiments, a
path-planning module can utilize a shape Jacobian to determine the
required level of steering inside the cochlea. The shape Jacobian
can define the relationship between the instantaneous velocity and
the time derivative of an error vector describing the difference
between the actual position of tele-robotic device and a
time-varying curve that defines its desired shape. That is, the
shape Jacobian can be used to determine the required level of
steering inside the cochlea by comparing the actual position
against the theoretical position and compensating for the
difference. For example, the actual position of the insertion
module can be calculated by using equation 5 wherein d represents
the current depth of insertion into the body (e.g., insertion
displacement), the active-bending electrode array is divided into m
segments, and the configurations of m+1 points along the inserted
portion by p({tilde over (q)}) where {tilde over
(q)}=[q.sub.e.sup.l,q.sub.p.sup.l].sup.l refers to the augmented
joint variables' vector. The theoretical location in the body can
be determined using equation 6, wherein p.sub.d is a vector of m+1
configurations along the curve c(s): .fwdarw..sup.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)}=[q.sub.e.sup.l,q.sub.p.sup.l].sup.l.
p ( q ~ ) = [ r ( L ) , [ r ( L - j m d ) ] t ] t j = 1 , 2 , 3 m (
5 ) P d = [ c ( L ) , [ c ( L - j m d ) ] t ] t j = 1 , 2 , 3 m ( 6
) ##EQU00003## e(d): p(q)-P.sub.d. (7)
Min.sub.{tilde over (q)}(e.sup.le) (8)
[0062] Additionally or alternatively, a path planning module in
accordance with some embodiments may calculate the path of an
electrode array as follows. Let s.sub.q represent the electrode
insertion depth and let .theta..sub.c(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 .PHI. and the minimum is
found by numerical interpolation between the columns that best
approximate the minimum value of the objective function.
argmin q .intg. L - s q L ( .theta. c ( s ) - .theta. ( s ) 2 ) ( 9
) ##EQU00004##
[0063] 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(.theta.)
refers to the distance between the inserted portion of the
electrode array and the wall of the cochlea and .theta. 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.
E _ = .intg. .theta. m i n .theta. m ax E ( .theta. ) .theta. / (
.theta. ma x - .theta. m i n ) ( 10 ) ##EQU00005##
[0064] 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, r.sub.c, and the curve
of the outer wall of the cochlea, r.sub.l. Using these polynomial
representations a distance metric
e(.theta.)=.parallel.r.sub.c(.theta.)-r.sub.l(.theta.).parallel..sub.2
.theta..epsilon.[0,.phi.] can be calculated (where .phi. is the
insertion angle) and averaged for every insertion angle during the
insertion as shown in equation (11).
e _ = .PHI. - 1 .intg. 0 .PHI. e ( .theta. ) .theta. ( 11 )
##EQU00006##
[0065] 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.
[0066] In some embodiments, the speed of insertion is adjusted to
minimize the force of insertion. For example, referring to equation
12, f.sub.s refers to the force and m.sub.s refers to force and
moment measured by a force sensor. {dot over (X)}.sub.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)}.sub.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)}.sub.g are represented by .nu..sub.ins and .nu..sub.l. 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)}.sub.g=.nu..sub.ins{circumflex over
(z)}.sub.g+.nu..sub.l((I-{circumflex over (z)}.sub.g{circumflex
over (z)}.sub.g.sup.l)f.sub.s/.parallel.(I-{circumflex over
(z)}.sub.g{circumflex over (z)}.sub.g.sup.l)f.sub.s.parallel..sub.2
(12)
[0067] The insertion speed (i.e., .nu..sub.ins) can be determined
by equation 13. Where .nu..sub.min and .nu..sub.max are the minimal
and maximal tolerable insertion speeds. The parameter t can be
determined based on disparity between the measured insertion force
intensity f.sub.ins=f.sub.s.sup.l{circumflex over (z)}.sub.g and
the magnitude of the typical insertion forces {tilde over
(f)}(.theta.) 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
.alpha. and .beta. can be determined experimentally. Parameter
.beta. will have an inverse relationship with .nu..sub.ins (i.e.,
as .nu..sub.ins decreases as a result of large insertion forces,
.beta. will be increased to provide more motion in the direction of
the electrode involute).
.nu..sub.ins=.nu..sub.min+t.alpha.(.nu..sub.max-.nu..sub.min),t.epsilon.-
[0,1],.alpha..epsilon. (13)
t=({tilde over (f)}(.theta.)=f.sub.ins/{tilde over (f)}(.theta.)
(14)
[0068] 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. f.sub.end refers to any
force action on the tip of the electrode array to prevent it from
sliding against the walls of the cochlea. f.sub.ende.sup.u.theta.
refers to the required force to overcome f.sub.end acting at the
tip of the electrode array. .theta. refers to the total contact
angle between the cochlea and the electrode array.
f.sub.se.sup.u.theta. refers to the expression for the coulomb
friction due to contact pressure generated by the bending rigidity
of the electrode array.
f=f.sub.ende.sup.u.theta.+f.sub.se.sup.u.theta. (15)
[0069] 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.
* * * * *