Flexible circuit electrode array
A flexible circuit electrode array with more than one layer of metal traces comprising: a polymer base layer; more than one layer of metal traces, separated by polymer layers, deposited on the polymer base layer, including electrodes suitable to stimulate neural tissue; and a polymer top layer deposited on the polymer base layer and the metal traces. 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 many 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.
1. A flexible circuit comprising:
a polymer base layer;
a first metal layer on the polymer base layer patterned to form first traces, first electrodes and first bond pads;
a polymer interlayer on the polymer base layer and the first traces, first electrodes and first bond pads patterned to expose the first electrodes and first bond pads;
a second metal layer on the polymer interlayer patterned to form second traces, second electrodes and second bond pads;
a polymer top layer on the polymer interlayer and the second traces, second electrodes and second bond pads patterned to expose the first bond pads, first electrodes, second bond pads and second electrodes; and
wherein an array portion including the first electrodes and second electrodes is embedded in an curved polymer body, made of polymer softer than the polymer base layer.
2. The flexible circuit according to claim 1 , further comprising electrode coatings plated on the first electrodes and second electrodes in the polymer top layer.
3. The flexible circuit according to claim 2 , wherein the electrode coating is platinum grey.
4. The flexible circuit according to claim 2 , wherein the electrode coating protrudes above the polymer top layer.
5. The flexible circuit according to claim 1 , wherein the first electrodes and second electrodes are shaped as a circle, star, square, ring or other geometric arrangement.
6. The flexible circuit according to claim 1 , wherein the polymer base layer, polymer interlayer and polymer top layer are biocompatible.
7. The flexible circuit according to claim 1 , wherein the polymer base layer is polyimide, thermoplastic polyimide, silicone, parylene, LCP polymers, epoxy resin, PEEK, TPE, or mixtures thereof.
8. The flexible circuit according to claim 1 , wherein the polymer interlayer is polyimide, thermoplastic polyimide, silicone, parylene, LCP polymers, epoxy resin, PEEK, TPE, or mixtures thereof.
9. The flexible circuit according to claim 1 , wherein the first metal layer and second metal layer are biocompatible.
10. The flexible circuit according to claim 1 , wherein the first metal layer and second metal layer are titanium, platinum, palladium, iridium, gold, silver, niobium, titanium nitride, iridium oxide, ruthenium, ruthenium oxide, rhodium or metal alloys or metal layers thereof.
11. The flexible circuit according to claim 1 , wherein the first metal layer and second metal layer include an adhesion layer and a conducting layer.
12. The flexible circuit according to claim 11 , wherein the adhesion layer contains titanium.
13. The flexible circuit according to claim 11 , wherein the conducting layer includes platinum.
14. The flexible circuit according to claim 1 , further comprising openings in the polymer interlayer and metal vias through the interlayer connecting at least one of the first metal traces with the second metal traces.
15. The flexible circuit according to claim 1 , wherein the polymer body is curved to match the curvature of a retina.