Abstract:
A connector ( 1 ) and method of making electrical connection between an electrical conductor ( 7, 11 ) and a removable electrical device ( 2 ). The connector ( 7, 11 ) is an elastic material, such as silicone, that is both compatible with the environment and is an electrical insulator. It forces contact between the electrical device ( 2 ) and integral contacts ( 10, 13 ) in the connector ( 1 ) by virtue of its elasticity. The electrodes ( 4, 6 ) and the electrical connections are protected from the environment to avoid electrical leakage or corrosion of the electrodes ( 4, 6 ).

Description:
CROSS REFERENCE TO RELATED APPLICATION 
   This application is a continuation-in-part of U.S. patent application Ser. No. 10/678,539 filed Oct. 3, 2003, now U.S. Pat. No. 6,821,154. 

   FIELD OF THE INVENTION 
   This invention relates to a connector for electrical devices and methods, and more particularly to connecting electrical wires to an implantable device to enable ease of connection and to minimize risk to the living tissue during and after surgery. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  illustrates a cut-away view of the connector for an implantable stimulator having a lead wire. Components are essentially figures of revolution about a central longitudinal axis. 
       FIG. 2  depicts a cutaway view of the connector for an implantable stimulator having a stimulating electrode extension. Components are essentially figures of revolution about a central longitudinal axis. 
       FIG. 3  depicts a view of the connector showing the increased wall thickness near the insertion opening. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1  provides a cutaway view of a preferred embodiment of a hollow boot connector  1 . The connector is comprised of an elastic casing  16 , preferably silicone elastomer or another material that is chosen to be compatible with the design environment. Selected silicone elastomers are biocompatible and preferred for applications involving implantation in living tissue. Silicone rubber is also known to provide enduring elastic properties in a warm saline environment. Further, the selected material is preferably an electrical insulator that minimizes leakage of electric current and that isolates the electrical device  2  from the environment. 
   The electrical casing  16 , in the relaxed state, is shorter than the length of its contents. The elastic casing  16  contains at least one insertion opening  18  (dashed line) that provides access through the wall of the casing  16  and into the inside of the hollow boot connector  1 , where the electrical device  2  is removably inserted. Although not evident in the figure, the edge of insertion opening  18  is shown as a single dashed line to indicate that said edge is fully rounded to reduce stress concentration. Further, as shown in  FIG. 3 , the wall thickness of casing  16  is progressively thickened  59  proximate the edge of insertion opening  18  in order to distribute tension stress in the edge over a larger area, and to insure that the peripheral distribution of axial compressive force is uniform, thereby eliminating any tendency to tilt the encased devices. It is known to the inventors and within the scope of the instant invention, but not illustrated herein, that a plurality of openings  18  may be present in elastic casing  16  such that there are, in essence, a plurality of bands or straps formed by the plurality of openings  18 . The electrical device  2  may either be inserted before being placed into service, or during enablement for service, or as a replacement for a prior device during actual service. The connector  1  enables positive and rapid insertion of the electrical device  2  under difficult conditions, such as in seawater or in living tissue during surgery. 
   It is understood that the electrical device  2  encompasses electronic devices, electrical circuit components, conductors, sensors, and stimulators, such as, but not limited to devices such as the BION microstimulator of Advanced Bionics Corporation. 
   The hollow boot connector  1  is further comprised of at least one electrical contact  10  that is integrally connected to an electrical conductor  7 , which is preferably a wire conductor  8  surrounded by a wire insulator  9 . The electrical conductor  7  is preferably connected to the first electrical contact  10  by a known technique, such as crimping, as shown by crimping connection  14 . Numerous embodiments rely on electrical conductor  7  to connect device  2  to a sensing or stimulating electrode comprising conductors  8  exposed at an effective location removed as desired from the location of device  2 , or connected to another component or device of a system. As alternative embodiments, any of the known methods of forming a connection between a wire and a contact is applicable in lieu of crimping, as is known in the art. Preferred materials for contacts  10 ,  13 , and  40 , and for electrodes  4 ,  6  and  34 , inexhaustibly include platinum, platinum-iridium alloys, titanium and its alloys, and stainless steel type 316L (low carbon), taken in combinations having known long-term electrochemical compatibility. 
   The elastic casing  16  preferably fits the electrical device  2  snugly such that when the electrical device  2  is inside the hollow boot connector  1 , the first electrical contact  10  is urged toward the first electrode  4  that forms part of electrical device  2  by the stretched elastic casing  16 . The first electrical contact  10  preferably has three, equally spaced nipple contacts  20  (two visible in the figure) that concentrate the contact stress between first electrical contact  10  and electrode  4 , thus insuring electric continuity. In a preferred embodiment, second end  24  has second electrical contact  13  urged toward second electrode  6  by the stretched elastic casing  16 , with second electrical contact  13  preferably also having three, equally spaced nipple contacts  23  that concentrate the contact stress, as described above. Preferred embodiments of contact  10  have three nipple contacts  20  in order to provide first electrical contact  10  with kinematic stability relative to electrode  4  when compressed by elastic casing  16 . Further, three nipple contacts are doubly redundant, and under normal circumstances, equally share the electrical current. Nipple contacts are point-like features having a contact curvature predetermined to increase the contact stress to a value somewhat higher than the film strength of any fluid or oxide film that would otherwise intervene. Sufficient contact pressure provides a low potential drop across each contact in order to reduce or eliminate electrochemical action. Additionally, sufficient contact pressure provides a low-resistance, low-noise current path that enhances the sensitivity of a sensing device. 
   Illustrated in  FIG. 1  is a two-conductor connector  1 , having a first end  22  with a first electrical conductor  7  and a second end  24  having a second electrical conductor  11  attached to the first electrical contact  10  at the first end  22  and the second electrical contact  13  at the second end  24 , respectively. In this configuration the elastic casing  16  is stretched when the electrical device  2  is inserted inside the hollow boot connector  1 , which in turn urges the respective electrical contacts against the first electrode  4  and the second electrode  6 . 
   In a preferred embodiment, the first electrical conductor  7  is integrally bonded to the elastic casing at the first end  22  to assure that there is no leakage or failure at the first end  22  which might reduce or eliminate electrical conductivity between the first electrode  4  and the first electrical contact  10 . The wire insulator  9  is preferably glued to the casing  16 , although it may be thermally bonded for equal effect. It will be obvious to one skilled in the art that a similar bond may be utilized at second end  24 . 
   To insure electrical isolation between electrodes, insertion opening  18  is positioned so that it does not expose first electrode  4  or second electrode  6  of electrical device  2  to the environment surrounding the connector  1 . Further, to insure electrical isolation between electrodes, at least one sealing ridge  26  may be added, in an alternative embodiment, to the inside of elastic casing  16 . The sealing ridge  26  is located between insertion opening  18  and either the first electrode  4  or second electrode  6 . Obviously, multiple sealing ridges may be added to facilitate an effective seal. A further embodiment adds a seal receiver  28  to electrical device  2 , which mates with sealing ridge  26  to enhance the sealing effectiveness. Further, a tie (suture) (not illustrated) may be placed around the outside of the elastic casing  16  either in lieu of the sealing ridge  26  or in conjunction with it, to assure a tight seal. Obviously, sealing ridges  26  are molded in axial locations (relaxed state) predetermined to correctly position the ridges at the seal receivers  28  when the boot is stretched. 
   First end shoulders  17  and second end shoulder  19  of casing  16  are made somewhat thicker in order to distribute stress over a larger area during the transition from axial tension to radial tension. 
   Illustrated in  FIG. 2  is a hollow boot connector  31  having a first end  55  and a single first conductor  46  that is comprised of a wire conductor  48  with wire insulator  49 . Analogous to that described previously, the elastic casing  53  has an insertion opening  38  to accept the electrical device  32  to the interior of connector  31 . When the electrical device  32  is inserted therein, the elastic casing  53  is stretched such that the electrical contact  40  and its three nipple contacts  50  (two visible in the figure) are urged into electrical contact with first electrode  34 . 
   Analogous to the embodiment previously presented, first conductor  46  is attached to electrical contact  40  by techniques know to one skilled in the art, preferably by crimping at crimp connection  44 . 
   In alternative embodiments, one or more sealing ridges  66  may be employed, optionally with a matching seal receiver  68  in the surface of electrical device  32  to form a tight seal. Ties, sutures, or compression bands (not illustrated) may be placed on the outside of connector  31  to facilitate the seal. 
   In the embodiment shown in  FIG. 2 , the electrical device  32  has a second electrode  36  that is further comprised of an electrode extension  52 . At least a portion of electrode extension  52  protrudes from the second end  56  of connector  31  through an aperture  54  in the elastic casing  53 . It is obvious that there are many electrical devices and many electrode configurations available that may be utilized with the hollow boot connector  31 . The presented embodiments are not limiting, but are illustrative of connector  31  applications. 
   The shoulders of electrodes  10 ,  13 , and  40  are rounded to reduce or eliminate any tendency to cut boots  16  and  53 . Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.