Flexible Circuit Electrode Array

Abstract

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. 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.

1 . A flexible circuit electrode array comprising: 
 a polymer base layer;    metal traces deposited on said polymer base layer, including electrodes suitable to stimulate neural tissue; and    said polymer base layer and said metal traces are embedded in a body having a generally oval shape in the plane of the retina, said oval shaped body being curved such that it substantially conforms to the spherical curvature of the retina of the recipient's eye.    
   
   
       2 . The flexible circuit electrode array according to  claim 1  comprising at least one mounting aperture in said body for attaching the electrode array to the retina with a tack.  
   
   
       3 . The flexible circuit electrode array according to  claim 1  wherein said oval shaped body has a radius of spherical curvature, which is smaller than the radius of the curvature of the eye.  
   
   
       4 . The flexible circuit electrode array according to  claim 1  wherein said oval shaped body is made of a soft polymer containing silicone having a hardness of about 50 or less on the Shore A scale as measured with a durometer.  
   
   
       5 . The flexible circuit electrode array according to  claim 1  wherein said flexible circuit cable portion has an angle of about 45° to about 180°.  
   
   
       6 . The flexible circuit electrode array according to  claim 5 , wherein said flexible circuit cable portion has a bend with an angle of about 60° to about 120°.  
   
   
       7 . The flexible circuit electrode array according to  claim 5 , wherein said flexible circuit cable portion has a bend with an angle of about 45° to about 180°.  
   
   
       8 . The flexible circuit electrode array according to  claim 7 , wherein said flexible circuit cable portion has a bend with an angle of about 60° to about 120°.  
   
   
       9 . The flexible circuit electrode array according to  claim 1 , wherein said flexible circuit cable portion has a fold within the attached flexible circuit electrode array with an angle of about 1° to about 180°.  
   
   
       10 . The flexible circuit electrode array according to  claim 9 , wherein said flexible circuit cable portion has a fold within the attached flexible circuit electrode array with an angle of about 20° to about 90°.  
   
   
       11 . The flexible circuit electrode array according to  claim 1 , wherein said flexible circuit cable portion has a horizontal angle within the attached flexible circuit electrode array of about 1° to about 90°.  
   
   
       12 . The flexible circuit electrode array according to  claim 11 , wherein said flexible circuit cable portion has a horizontal angle within the attached flexible circuit electrode array of about 10° to about 45°.  
   
   
       13 . The flexible circuit electrode array according to  claim 1 , wherein said flexible circuit cable portion comprises at least one grooved or rippled pad for capturing a mattress suture.  
   
   
       14 . The flexible circuit electrode array according to  claim 1 , wherein said flexible circuit electrode array is positioned on the surface of the body having a generally oval shape.  
   
   
       15 . The flexible circuit electrode array according to  claim 14 , wherein soft insulating material is positioned on the surface between said electrodes.  
   
   
       16 . The flexible circuit electrode array according to  claim 1 , wherein a film containing a soft polymer is applied on said flexible circuit cable portion.  
   
   
       17 . The flexible circuit electrode array according to  claim 16 , wherein said film containing a soft polymer contains silicone.  
   
   
       18 . The flexible circuit electrode array according to  claim 16 , wherein said film containing a soft polymer comprises a ladder like structure.  
   
   
       19 . The flexible circuit electrode array according to  claim 16 , wherein a film containing a soft polymer contains beads and/or bumpers.  
   
   
       20 . A method of making a flexible circuit electrode array comprising: 
 depositing a polymer base layer;    depositing metal on said polymer base layer;    patterning said metal to form metal traces;    depositing a polymer top layer on said polymer base layer and said metal traces; and    heating said flexible circuit electrode array in a mold to form a three dimensional shape in said flexible circuit electrode array.