Source: http://www.google.com/patents/US8078284?ie=ISO-8859-1&dq=U.S.+Patent+
Timestamp: 2014-07-25 19:36:34
Document Index: 621608340

Matched Legal Cases: ['Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 20020111658']

Patent US8078284 - Retinal prosthesis with a new configuration - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign in<nobr>Advanced Patent Search</nobr>PatentsPolymer materials are useful as electrode array bodies for neural stimulation. They are particularly useful for retinal stimulation to create artificial vision, cochlear stimulation to create artificial hearing, and cortical stimulation, and many related purposes. The pressure applied against the retina,...http://www.google.com/patents/US8078284?utm_source=gb-gplus-sharePatent US8078284 - Retinal prosthesis with a new configurationAdvanced Patent SearchPublication numberUS8078284 B2Publication typeGrantApplication numberUS 11/523,965Publication dateDec 13, 2011Filing dateSep 19, 2006Priority dateMay 25, 2004Also published asUS8510939, US20070055336, US20080275527, US20130289688Publication number11523965, 523965, US 8078284 B2, US 8078284B2, US-B2-8078284, US8078284 B2, US8078284B2InventorsRobert J. Greenberg, Matthew J. McMahon, James Singleton Little, Kelly H. McClure, Brian V. Mech, Neil Hamilton Talbot, Jordan M. NeysmithOriginal AssigneeSecond Sight Medical Products, Inc.Export CitationBiBTeX, EndNote, RefManPatent Citations (16), Referenced by (1), Classifications (22), Legal Events (1) External Links: USPTO, USPTO Assignment, EspacenetRetinal prosthesis with a new configurationUS 8078284 B2Abstract Polymer materials are useful as electrode array bodies for neural stimulation. They are particularly useful for retinal stimulation to create artificial vision, cochlear stimulation to create artificial hearing, and cortical stimulation, and many related purposes. The pressure applied against the retina, or other neural tissue, by an electrode array is critical. Too little pressure causes increased electrical resistance, along with electric field dispersion. Too much pressure may block blood flow. Common flexible circuit fabrication techniques generally require that a flexible circuit electrode array be made flat. Since neural tissue is almost never flat, a flat array will necessarily apply uneven pressure. Further, the edges of a flexible circuit polymer array may be sharp and cut the delicate neural tissue. By applying the right amount of heat to a completed array, a curve can be induced. With a thermoplastic polymer it may be further advantageous to repeatedly heat the flexible circuit in multiple molds, each with a decreasing radius. Further, it is advantageous to add material along the edges. It is further advantageous to provide a fold or twist in the flexible circuit array. Additional material may be added inside and outside the fold to promote a good seal with tissue.
18. The flexible circuit electrode array of claim 1, wherein the electrode array is coupled to a drug reservoir, wherein drugs are delivered from the drug reservoir to the retina based on the stimulation signals to the flexible circuit electrode array. Description
CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Application No. 60/718,660, entitled �System Architecture and Stimulation Methods for a Retinal Prosthesis�, filed Sep. 19, 2005, the disclosures of which is incorporated herein by reference.
This application claims the benefit of U.S. Provisional Application No. 60/718,769 now abandoned, entitled �System for Testing and Configuring a Retinal Prosthesis�, filed Sep. 19, 2005, the disclosures of which is incorporated herein by reference.
This application claims the benefit of U.S. Provisional Application No. 60/718,779, �Transretinal Flexible Circuit Electrode Array�, filed Sep. 19, 2005, the disclosures of all which is incorporated herein by reference.
This application claims the benefit of U.S. patent application Ser. No. 11/521,281, �Transretinal Flexible Circuit Electrode Array�, filed Sep. 13, 2006, the disclosures of which is incorporated herein by reference.
This application claims the benefit of U.S. patent application Ser. No. 11/413,689, �Flexible circuit electrode array�, filed Apr. 28, 2006, which is a Continuation-In-Part of U.S. application Ser. No. 11/207,644, �Flexible circuit electrode array�, filed Aug. 19, 2005 which claims the benefit of U.S. Provisional Application No. 60/676,008 �Thin Film Electrode Array�, filed Apr. 28, 2005, the disclosures of all are incorporated herein by reference.
This application is a Continuation-in-Part of the U.S. patent application Ser. No. 10/918,112 �Retinal prosthesis�, filed Aug. 13, 2004 now U.S. Pat. No. 7,263,403, which claims the benefit of U.S. Provisional Application No. 60/574,130 �Retinal Prosthesis�, filed May 25, 2004, the disclosures of all are incorporated herein by reference.
FIELD OF THE INVENTION The present invention is generally directed to neural stimulation and more specifically to an improved electrode array for neural stimulation.
SUMMARY OF THE INVENTION Polymer materials are useful as electrode array bodies for neural stimulation. They are particularly useful for retinal stimulation to create artificial vision, cochlear stimulation to create artificial hearing, or cortical stimulation for many purposes. Regardless of which polymer is used, the basic construction method is the same. A layer of polymer is laid down, commonly by some form of chemical vapor deposition, spinning, meniscus coating or casting. A layer of metal, preferably platinum, is applied to the polymer and patterned to create electrodes and leads for those electrodes. Patterning is commonly done by photolithographic methods. A second layer of polymer is applied over the metal layer and patterned to leave openings for the electrodes, or openings are created later by means such as laser ablation. Hence the array and its supply cable are formed of a single body. Alternatively, multiple alternating layers of metal and polymer may be applied to obtain more metal traces within a given width.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following description is of the best mode presently contemplated for practicing the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of describing the general principles of the invention. The scope of the invention should be determined with reference to the claims.
FIG. 6 depicts a side view of the prosthesis insight of the eye with an angle K of the flexible circuit cable 12 and a fold A between the circuit electrode array 10 and the flexible circuit cable 12. The angle K is about 45�-180� and preferably 80�-100�. The fold K also called knee is advantageous because it decreases pressure which would be applied by the flexible circuit cable 10.
Human vision provides a field of view that is wider than it is high. This is partially due to fact of having two eyes, but even a single eye provides a field of view that is approximately 90� high and 140� to 160� degrees wide. It is therefore, advantageous to provide a flexible circuit electrode array 10 that is wider than it is tall. This is equally applicable to a cortical visual array. In which case, the wider dimension is not horizontal on the visual cortex, but corresponds to horizontal in the visual scene.
FIG. 16 depicts the flexible circuit array 1 before it is folded and attached to the implanted portion containing an additional fold A between the flexible electrode array 10 and the flexible cable 12. The angle in the fold A, also called ankle, has an angle of 1�-180�, preferably 80�-120�. The ankle is advantageous in the process of inserting the prostheses in the eye and attaching it to the retina.
FIG. 19 depicts a top view of a flexible circuit array and flexible circuit cable showing the additional horizontal angel H between the flexible electrode array 10 and the flexible cable 12. The angle H is from about 1� to about 90� and preferably from about 30� to about 60�.
FIG. 37 depicts the top view of the flexible electrode array 10 being enveloped within an insulating material 11. The electrode array 10 comprises oval-shaped electrode array body 10, a plurality of electrodes 13 made of a conductive material, such as platinum or one of its alloys, but that can be made of any conductive biocompatible material such as iridium, iridium oxide or titanium nitride. The electrode array 10 is enveloped within an insulating material 11 that is preferably silicone. �Oval-shaped� electrode array body means that the body may approximate either a square or a rectangle shape, but where the corners are rounded. This shape of an electrode array is described in the U.S. Patent Application No. 20020111658, entitled �Implantable retinal electrode array configuration for minimal retinal damage and method of reducing retinal stress� and No. 20020188282, entitled �Implantable drug delivery device� to Rober J. Greenberg et al., the disclosures of both being incorporated herein by reference.
The retinal electrophysiology and human clinical testing are designed to provide valuable information required to make device development decisions. In some cases, device performance is limited by physical and electrical constraints�i.e. material charge density limits or voltage limits in today's integrated circuit technology. In other cases it is limited by the biology�i.e. tissue damage tolerance evaluated above, retinal biology, or eye movements.
The simultaneous stimulation of two or more very small electrodes spaced 60 μm apart results in independent activation of ganglion cells near each stimulation site. Increasing the number of place-pitch steps a factor of 2-9� over single electrodes available to cochlear implant listeners.
The proportion of the total current directed to each electrode will vary between p=1 only the first electrode stimulated to p=0 only the second of the two electrodes stimulated. If both electrodes are stimulated with equal amounts of current, normalized for electrode sensitivity, presented to each electrode then, p=0.5. On each trial, multiple stimuli p=1, p=0.5 or p=0 separated in time will be presented in random order, and the subject asked to press a key every time the stimulus appears further to the right than the previous one assuming laterally adjacent electrodes. If this experiment results in the perception of three phosphenes that are distinctly located in space, then a second experiment will be conducted where more discrete levels for p are selected. Analysis of the function relating current ratio (p) to the perceived spatial position will be used to determine whether current steering can produce reliable shifts in the position of the resulting phosphene and how many intervening �virtual electrodes� can be produced.
For an epiretinal prosthesis, the size of the electrode array is dictated by surgical concerns to about 5�6 mm. This is the area which fits comfortably between the large �arcade� blood vessels which surround the macula. If an array were larger than this, blood flow to the distant retina might be compromised. It is currently unknown how large a subretinal array can be, but surgical limitations may limit its size to something similar.
(4) Development of an integrated array and channel selector IACS, including a means of forming the array. The IACS will contain a 1-to-4 channel demultiplexer and will have integrated electronics on the �back� flat surface and electrodes on the �front� formed surface. It is anticipated that the IACS will be made from silicon using a combination of standard micro-fabrication procedures to integrate the required electrical components and custom MEMS engineering to shape the array portion and provide electrical feedthroughs to the electrodes.
Electrophysiology�Patch pipettes will be used to make small holes in the inner limiting membrane and ganglion cells will be targeted under visual control. Light responses will be used to assign the targeted cell to a known ganglion cell type. Spiking will be recorded with a cell-attached patch electrode 5-6 MΩ, filled with superfusate. Excitatory and inhibitory input currents will be measured with whole-cell patch clamp electrodes 6-7 MΩ.
This suggests that one or more spikes are buried within this transient current. To reveal the spike(s) it is reasoned that the response in TTX did not contain neural activity and was therefore mainly electrical artifact generated by the stimulus pulse. Subtraction of the electrical artifact TTX response from the control response reveals an additional pulse-elicited spike (inset, solid trace, n=5/5). The waveform of this spike is nearly identical to the average light-elicited spike for this cell (inset, dotted trace). It is referred to this single spike as the �early-phase� spike and referred to the subsequent series of multiple spikes biphasic waveforms as �late-phase� spikes. Similar results are found in all ganglion cell types of the rabbit retina. The onset of the TTX-extracted pulse-elicited spike closely follows the onset of the cathodic pulse (mean=580 μs, range=400-680 μs, n=5). Without TTX, it is difficult to precisely determine the onset of the elicited spike, but comparison of control records in 5 TTX and 15 non-TTX experiments are similar, providing additional support that the elicited spike closely and consistently follows the stimulus pulse onset.
The threshold is the stimulation intensity at which the subject performs at 50% correct, corrected for the false alarm rate in the case of the yes-no paradigm) and is 80% correct performance in the case of the procedure. Errors in the threshold estimation are characterized by the 90% confidence interval in which the �true� threshold value will fall.
Brightness or size matching�The subject is presented with two intervals: one containing a �standard� stimulation pulse whose parameters will remain fixed throughout the experiment and a second containing a �matching� stimulation pulse produced using different parameters. The subject selects the interval that contained the brighter stimulus. If they report that the matching pulse was brighter, its intensity will be reduced on the next trial. If they report that the standard pulse was brighter, the matching pulse's intensity will be increased on the next trial. The technique described above will be used to fit the data and the 50% correct value is considered the point of �subjective equality�.
Eye movement recording�A video-based eye tracking system (Arrington Research) is used to record eye position, including nystagmus. Because the pupil position of blind subjects cannot be calibrated to the position of visual targets using usual techniques, a novel calibration technique is developed that maps the pupil position to the location of tactile calibration points across the visual field.
To determine the smallest safe electrode size for a high resolution prosthetic, it is necessary to know whether perceptual thresholds for electrical stimulation are determined by the amount of charge or the charge density. If thresholds are determined by the total charge, then the small electrodes required to increase spatial resolution are likely to result in charge densities that reach unacceptable levels. Charge thresholds generally decrease with electrode size. The solid line in FIG. 56 represents a line of constant charge density (0.2 mC/cm2) which yields a correlation coefficient R2=0.75. While larger electrodes clearly require higher charge injection for successful stimulation, the data points lie close to the line denoting constant charge density. These stimulation experiments in isolated retina show that spikes can be readily elicited in ganglion cells, even with very small electrodes, without exceeding the charge density limit for platinum gray electrodes (1.0 mC/cm2). Solid circles denote the average data from 3 human subjects tested using 250 μm and 500 μm electrodes (means�standard deviation).
Recent threshold measurements in transgenic rats with severely degenerated retinas showed that spike thresholds in degenerated retina are not different from those of normal retina (FIG. 57). These findings suggest that very small electrodes can directly stimulate ganglion cells. Avarage threshold currents in normal (dark bars) and degenerated (light bars) retinal using 0.1 ms pulses (�SEM). Three electrode diameter ranges are shown. Number indicate numbers of stimulated cells. To verify this, blockers of synaptic transmission were added to the perfusion. Spike shapes, latencies, and response rates were unchanged in 9 cells tested (FIG. 58), indicating that ganglion cells were activated directly and not by presynaptic input from bipolar cells. Response to 10 stimulus pulses in a cell with spikes at latency 5.5 ms in rat retina. Bottom: A combination of glutamate receptor antagonists was added to the perfusion solution. The finding that thresholds are determined by charge density (FIG. 56), and our demonstration that these results also hold for degenerated retina (FIG. 58) suggest that it may indeed be possible to significantly reduce electrode sizes.
FIG. 60 shows the ability of two subjects to discriminate between a single stimulated electrode and a pair of stimulated electrodes. The currents needed to produce equal apparent brightness for the single pulse and the pulse pair were equalized prior to the start of the experiment and then the current was jittered on each trial to prevent subjects from using small brightness changes as a cue to perform the task. FIG. 60 shows a two-point discrimination performance. The x-axis represents the distance on the retina between the stimulated electrodes (1 mm on the retina is equivalent to 3� of visual angle). Performance is shown for two subjects; performance for horizontally (solid line) and vertically (dashed lines) aligned electrodes is shown separately. Error bars represent binominal error estimates of the mean.
FIG. 68 shows example curves showing brightness ratings as a function of stimulation intensity for S5 and S6. Brightness ratings were measured by presenting each subject with an easily visible �standard pulse� (rated by default as a �10�) and having the subject rate subsequently presented pulses that varied in amplitude �20� if they were twice as bright as the standard pulse, �5� if they were half as bright as the standard pulse, and so on. The standard pulse was presented in between each trial. In the case of normal vision, apparent brightness increases monotonically but compressively with luminance. It seems that apparent brightness also increases monotonically but slightly compressively with stimulation amplitude.
The brightness functions of different electrodes using a two interval brightness matching technique were compared. In one of the two intervals subjects were presented with a pulse on one electrode at a standard current intensity. In the second of the two intervals (these two intervals were presented in a random order) subjects were presented with a pulse on a different test electrode. Subjects judged which of the pulses were brighter and the current intensity on the test electrode was varied to find the value where standard and test pulses appeared equally bright. This procedure was repeated for a range of current levels on the standard electrode. FIG. 69 plots the test electrode current required to match the �standard� electrode for 2 electrodes in two subjects. The x-axis represents the current intensity on the standard electrode and the y-axis represents current intensity on two test electrodes. A linear fit with zero intercept (shown with dashed lines) describes the data well. These functions will allow us to match brightness across electrodes so that objects will not change in their apparent brightness as they move to a different position on the electrode array. It is also possible to indirectly measure the number of brightness steps that subjects can discriminate from these data based on the slopes of the brightness matching function. These calculations suggest that subjects can discriminate 6 brightness levels with 95% accuracy, similar to the estimate from brightness rating measurements.
It was possible to consistently generate one spike per pulse over a wide range of stimulus amplitudes, as shown in FIG. 70 c. The two columns represent two different time scales. The left column indicates that at above threshold levels, stimulus pulses elicited spikes, as shown by the small deflection in the stimulus artifact trace (vertical arrow, left gray box). The threshold at which spiking occurred was determined by comparing the shape of the early phase response to the shape of the response when spiking activity was blocked by TTX (FIG. 70 b). This early phase response persisted for all stimulus levels above threshold. For this cell the threshold was around 100-120 μA. For the population (n=13), the mean threshold amplitude was 193�64 μA.
At higher amplitude levels, late phase spiking was elicited (FIG. 70 c right column, right gray box). For this cell late phase spiking was observable at stimulus amplitudes above 340 μA. Thus, late phase spikes were not observed until stimulation levels were almost 2.8� threshold amplitude.
The flexible circuit electrode array comprises at least one mounting aperture in said body for attaching the electrode array to the retina with a tack. The oval shaped body has a radius of spherical curvature, which is smaller than the radius of the curvature of the eye. The oval shaped body is made of a soft polymer containing silicone having hardness of about 50 or less on the Shore A scale as measured with a durometer. The flexible circuit cable portion has an angle of about 45� to about 180�. The flexible circuit cable portion has a bend with an angle of about 60� to about 120�. The flexible circuit cable portion has a bend with an angle of about 45� to about 180�. The flexible circuit cable portion has a bend with an angle of about 60� to about 120�. The flexible circuit cable portion has a fold within the attached flexible circuit electrode array with an angle of about 1� to about 180�. The flexible circuit cable portion has a fold within the attached flexible circuit electrode array with an angle of about 20� to about 90�. The flexible circuit cable portion has a horizontal angle within the attached flexible circuit electrode array of about 1� to about 90�. The flexible circuit cable portion has a horizontal angle within the attached flexible circuit electrode array of about 10� to about 45�. The flexible circuit cable portion comprises at least one grooved or rippled pad for capturing a mattress suture. The flexible circuit electrode array is positioned on the surface of the body having a generally oval shape. The soft insulating material is positioned on the surface between said electrodes. The film containing a soft polymer is applied on said flexible circuit cable portion. The film containing a soft polymer contains silicone. The film containing a soft polymer comprises a ladder like structure. The film containing a soft polymer contains beads and/or bumpers.
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