Self-folding paddle lead and method of fabricating a paddle lead

Abstract

In one embodiment, a medical lead comprises a lead body for conducting electrical pulses and a paddle. The paddle includes an intermediate metal layer, at least an insulative polymer backing layer, and an insulative polymer covering layer. The intermediate metal layer comprises a plurality of features defined by gaps in the metal material in the metal layer such that each feature is electrically isolated from each other feature, wherein each feature includes a respective connector element that is electrically coupled to at least one conductor within the lead body, wherein a portion of the insulative polymer covering layer is exposed above each feature to define a respective electrode for the corresponding feature. Also, the paddle possesses shape memory to cause the paddle to assume a substantially planar orientation when the shape memory is in a relaxed state.

1 . A medical lead for delivering electrical stimulation to tissue of a patient, the medical lead comprising:
 a lead body for conducting electrical pulses through a plurality of conductors; and   a paddle for delivering the electrical pulses from the plurality of conductors to tissue of the patient, wherein the paddle includes:
 (i) an intermediate metal layer; and 
 (ii) at least an insulative polymer backing layer and an insulative polymer covering layer; 
 wherein the intermediate metal layer comprises a plurality of features defined by gaps in the metal material in the metal layer such that each feature is electrically isolated from each other feature, wherein each feature includes a respective connector element that is electrically coupled to at least one conductor within the lead body, wherein a portion of the insulative polymer covering layer is exposed above each feature to define a respective electrode for the corresponding feature; 
 wherein the paddle possesses shape memory to cause the paddle to assume a substantially planar orientation when the shape memory is in a relaxed state. 
   
   
   
       2 . The medical lead of  claim 1  wherein the guide structures are scribed into at least one of a plurality of separate features of the paddle, the guide structures being adapted to control folding or unfolding of the paddle. 
   
   
       3 . The medical lead of  claim 1  wherein intermediate metal layer possesses a thickness of approximately one mil. 
   
   
       4 . The medical lead of  claim 1  wherein the insulative polymer backing layer possesses a thickness of approximately 25.4 to 152.4 microns. 
   
   
       5 . The medical lead of  claim 1  wherein the paddle comprises a slit in the paddle and the first longitudinal portion folds over the second longitudinal portion upon application of force to the paddle. 
   
   
       6 . The medical lead of  claim 1  further comprising:
 a support structure that extends substantially along a longitudinal direction of the paddle, the paddle being affixed to a flat surface of the support structure and the medical lead being affixed to a concave surface of the support structure.   
   
   
       7 . The medical lead of  claim 6  wherein the support structure is an extruded or injection-molded biocompatible polymer structure. 
   
   
       8 . A method of fabricating a paddle adapted for electrical stimulation of tissue of a patient, the method comprising:
 providing a layer of conductive material;   laminating a film of insulative material on a first side of the layer of conductive material;   creating a paddle form in the layer of conductive material, the paddle form including: (i) at least a first segment and a second segment with a plurality of electrodes on each segment; and (ii) one or more guide structures proximate to at least one end of the paddle form, wherein the one or more guide structures are adapted to distribute force into a body of the paddle form to control folding or unfolding of the paddle form; and   providing an insulative layer over the paddle on a second side of the layer of conductive material;   wherein the paddle possesses shape memory that causes the paddle to assume a substantially planar state when the shape memory is in a relaxed state.   
   
   
       9 . The method of  claim 8  wherein the providing an insulative layer comprises:
 spin coating an insulative polymer on the paddle.   
   
   
       10 . The method of  claim 8  wherein the creating comprises:
 laser scribing the conductive material without completely cutting through the film of insulative material.   
   
   
       11 . The method of  claim 8  further comprising:
 removing portions of insulative material to expose conductive material corresponding to the plurality of electrodes.   
   
   
       12 . The method of  claim 8  wherein the guide structures are longitudinal elements that distribute force into the body of the paddle to cause the paddle to fold. 
   
   
       13 . The method of  claim 8  further comprising:
 mechanically coupling the paddle to a support structure; and   electrically coupling the electrodes of the paddle to conductors of a medical lead.   
   
   
       14 . The method of  claim 13  wherein the medical lead is mechanically coupled to a concave surface of the support structure and the paddle is mechanically coupled to a flat surface of the support structure. 
   
   
       15 . The method of  claim 8  wherein, after the creating the paddle form is performed, the conductive material occupies substantially all of the surface area of the paddle. 
   
   
       16 . The method of  claim 8  wherein the paddle form comprises a slit in the conductive material and the first segment folds over the second segment when either of the guide structures experiences force by contact of the paddle with an interior surface of an insertion tool. 
   
   
       17 . The method of  claim 16  wherein the slit in the conductive material is covered by a highly elastic polymer material or hydrogel material. 
   
   
       18 . A method of positioning a paddle-style lead in a patient for electrical stimulation of tissue of the patient, comprising:
 inserting a paddle structure of the lead into an insertion tool or catheter, the paddle structure including at least a first longitudinal portion and a second longitudinal portion, the first and second longitudinal portions defining respective substantially planar surfaces having a plurality of electrodes, wherein contact of the paddle structure with an interior portion of the insertion tool or catheter causes one or several memory shape elements in the paddle structure to be subjected to a compressive force; and   advancing the paddle structure in a folded state through the insertion tool or catheter to exit the insertion tool or catheter within the patient, wherein the planar surfaces of the first and second longitudinal portions are disposed substantially adjacent to each other in the folded state;   wherein release of the compressive force on the one or several shape memory elements upon the exiting of the paddle from the insertion tool or catheter causes unfolding of the paddle structure to occur in a substantially lateral direction.   
   
   
       19 . The method of  claim 18  wherein the paddle structure comprises one or more guide structures that possess an arcuate shape to distribute force into the second longitudinal portion and one or more guide structures that possess a substantially linear shape to distribute force into the first longitudinal portion. 
   
   
       20 . The method of  claim 19  wherein the one or more guide structures of the first and second longitudinal portions cause the paddle to possess a differential in rigidity between the first and second longitudinal portions.