Abstract:
Medical devices include a separate enclosure that houses a battery and electrically isolates the battery from external conditions such as any metal enclosures and ultimately isolates the battery from body fluids. Thus, the separate enclosure attaches to a housing of a medical device and provides for modularity of the battery which allows, for instance, different size batteries to be used with the same medical device design. The separate enclosure further prevents stimulation current from leaking back to the battery housing by providing the electrical isolation.

Description:
TECHNICAL FIELD 
       [0001]    Embodiments relate to implantable medical devices that utilize battery power. More particularly, embodiments relate to implantable medical devices that utilize a battery that is located within a separate enclosure from other components of the medical device. 
       BACKGROUND 
       [0002]    Implantable medical devices utilize electrical power to function when performing a medical task such as electrical stimulation therapy. In order to provide the implantable medical device with autonomy from any external power source, an internal battery may be included to provide the electrical power. Conventionally, the battery is positioned within a hermetically sealed enclosure together with circuitry for controlling the operation of the medical device. 
         [0003]    The battery used for medical devices has an anode terminal and a cathode terminal but may also have an electrical potential relative to the anode and/or cathode that is present on a housing of the battery, particularly where the battery is a case neutral design. When the battery is mounted within the hermetically sealed enclosure of the implantable medical device, the battery housing is electrically isolated from the anode and/or cathode terminals as is appropriate. The battery is also electrically isolated from other electrical components of the medical device including an enclosure of the medical device and also electrical stimulation outputs. Likewise, the battery is isolated from related electrodes present on a medical lead that may be electrically connected to the electrical stimulation outputs. 
         [0004]    While having the battery within the hermetically sealed enclosure provides electrical isolation for the battery, there is a lack of modularity. For instance, if a larger sized battery is desired, the medical device that is designed to house the smaller battery may not be able to easily accommodate the larger battery. Thus, conventional designs do not provide adequate modularity while providing electrical isolation of the battery housing. 
       SUMMARY 
       [0005]    Embodiments address issues such as these and others by providing a separate enclosure for the battery that may be attached to the enclosure of the medical device to provide modularity. Thus, the separate enclosure may be constructed as necessary to accommodate the desired battery while the medical device may remain the same. Furthermore, the separate enclosure may insulate the battery housing from external conditions. 
         [0006]    Embodiments provide a method of electrically isolating a battery of a medical device. The method involves providing an outer enclosure, providing an insulation enclosure, and placing the battery inside of the insulation enclosure where the battery has battery terminals. The method further involves placing the insulation enclosure inside of the outer enclosure and coupling the outer enclosure to the medical device while the battery is inside of the insulation enclosure and while the insulation enclosure is inside of the outer enclosure. The battery terminals extend beyond the insulation enclosure and outer enclosure and into the medical device. 
         [0007]    Embodiments provide a medical device that includes a metal housing and circuitry within the metal housing. The medical device further includes an outer enclosure coupled to the metal housing and an insulation enclosure inside of the outer enclosure. The medical device also includes a battery inside of the insulation enclosure, and the battery has battery terminals that extend beyond the insulation enclosure and the outer enclosure and into the medical device and are electrically coupled to the circuitry. 
         [0008]    Embodiments provide a method of electrically isolating a battery of a medical device that involves providing an insulation enclosure and providing the battery inside of the insulation enclosure where the battery has battery terminals. The method further involves providing an adapter plate attached to the insulation enclosure and attaching the adapter plate to the medical device while the battery is inside of the insulation enclosure and while the insulation enclosure is attached to the adapter plate with the battery terminals extending beyond the insulation enclosure and the adapter plate and into the medical device. 
         [0009]    Embodiments provide a medical device that includes a metal housing, circuitry within the metal housing, an adapter plate attached to the metal housing, and an insulation enclosure attached to the adapter plate. The medical device further includes a battery inside of the insulation enclosure, the battery having battery terminals that extend beyond the insulation enclosure and the adapter plate and into the medical device and are electrically coupled to the circuitry. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  shows an operating environment for various embodiments where a medical system including a medical device has a battery included in a separate enclosure that is attached to an enclosure of the medical device. 
           [0011]      FIG. 2  shows an example of a medical device with a battery in a separate enclosure that is attached to the enclosure of the medical device. 
           [0012]      FIG. 3  shows a perspective view of one example of a battery in a separate enclosure. 
           [0013]      FIG. 4  shows an exploded view of the battery, an insulation enclosure, and an outer enclosure of the example of  FIG. 3 . 
           [0014]      FIG. 5A  shows a side view of the example of  FIG. 3 . 
           [0015]      FIG. 5B  shows a top view of the example of  FIG. 3 . 
           [0016]      FIG. 6  shows a perspective view of a second example of a battery in a separate enclosure. 
           [0017]      FIG. 7  shows an exploded view of the battery, an insulation enclosure, and an outer enclosure of the example of  FIG. 6 . 
           [0018]      FIG. 8A  shows a side view of the example of  FIG. 6 . 
           [0019]      FIG. 8B  shows a top view of the example of  FIG. 6 . 
           [0020]      FIG. 9  shows a perspective view of a third example of a battery in a separate enclosure. 
           [0021]      FIG. 10A  shows a side view of the example of  FIG. 9 . 
           [0022]      FIG. 10B  shows a top view of the example of  FIG. 9 . 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    Embodiments provide medical devices with batteries positioned within a separate enclosure that is attached to the enclosure of the medical device. The separate enclosure allows for battery modularity while also providing an insulation to isolate the battery housing from external conditions which prevents the battery housing from acting as an electrode. 
         [0024]      FIG. 1  shows a medical system  100  that includes a medical device  102  and a medical lead  106  that are implanted into a patient  110 . In this particular example, the medical system  100  including the medical device  102  and the medical lead  106  are implantable. The medical lead  106  includes a proximal end that has been inserted into a bore of a header block  104  of the medical device  102 . The distal end of the medical lead  106  includes electrodes  108  that are positioned at a target site where electrical stimulation therapy is to be provided. The medical device  102  is attached to a separate battery enclosure  112  that contains a battery that has a housing that is insulated from exterior conditions. 
         [0025]      FIG. 2  shows an example of the medical device  102  and a header block  104  mounted on the medical device  102  for receiving the lead  106 . The medical device  102  of this example includes stimulation circuitry  202  that provides electrical stimulation signals via a set of feed through conductors  206  that interconnect with corresponding electrical connectors  208  inside of the header block  104 . The medical device  102  of this example also includes an enclosure  210  that encloses the stimulation circuitry  202 . 
         [0026]    The separate battery enclosure  112  is then attached to the enclosure  210 . The separate battery enclosure  112  may include a plate, flange, or other structure  212  that allows the battery enclosure  112  to be laser seam welded to the enclosure  210 . The top of the enclosure  112  may serve to cap the bottom of the enclosure  210  with the laser seam weld providing the hermetic seal. The top of the enclosure  112  may also provide apertures to allow battery terminal pins  204  to pass from inside the battery enclosure  112  to the interior of the enclosure  210  where the battery terminal pins  204  may then physically and electrically connect to the stimulation circuitry  202 . 
         [0027]      FIGS. 3, 4, 5A, and 5B  show various views of one example of such a separate battery enclosure configuration  302 . An outer enclosure  304  which may be constructed of various materials including biocompatible metals like Titanium, Niobium, alloys thereof, and the like. The outer enclosure  304  has a pocket  307  that has a depth that fully receives an insulation enclosure  308 . The insulation enclosure  308  similarly defines a pocket  309  that has a depth that fully receives the battery  310 . The insulation enclosure  308  may be constructed of various materials such as Polyimide, Polyether Ether Ketone (PEEK), Polysulphone, LCP etc. 
         [0028]    As the battery  310  fits within the insulation enclosure  308  which then fits inside the outer enclosure  304 , the battery  310  is both housed in the separate enclosure configuration  302  while being electrically isolated from the outer enclosure  304  of the separate enclosure configuration  302 . Therefore, if the outer enclosure  304  is a conductor such as a biocompatible metal which is in contact with the body tissue and fluids, there will be no leakage of stimulation current directly back to the battery  310  because the insulation enclosure  308  provides the electrical isolation of the battery  310  from the outer enclosure  304 . Such leakage current is particularly troubling for bipolar stimulation where the return path for the stimulation current should be through the lead rather than through tissue between the electrodes and the battery. Furthermore, the hermetic seal of the outer enclosure  304  that occurs between a top plate  306  and the medical device housing  210  of  FIG. 2  prevents ingress of body fluids to the battery  310 . 
         [0029]    The battery  310  has terminal pins  312  that provide the cathode and anode terminals. In this particular example, the battery  310  also includes conductive ferrules  314  that are electrically isolated from the pins  312  by the presence of an insulator such as glass but are electrically connected to the battery housing to provide a feedthrough for the battery pins  312  to the interior of the enclosure  210 . The terminal pins  312  extend out of the pocket defined by the insulative enclosure  308  and the outer enclosure  304  and into the housing  210  of  FIG. 2 . These pins are also electrically isolated from the external conditions by the hermetic seal of the top plate  306  of the outer enclosure  304  to the housing  210 . 
         [0030]    In this example, a plug  315  can also be seen on the battery  310 . This plug  315  is present to provide a sealed closure to an opening in the battery housing that is used open when the battery  310  is being filled with electrolyte. 
         [0031]      FIGS. 6, 7, 8A, and 8B  show various views of a second example of a separate battery enclosure configuration  402 . An outer enclosure  404  which may be constructed of various materials including biocompatible metals like Titanium, Niobium, alloys thereof, and the like. The outer enclosure  404  has a pocket  405  that has a depth that fully receives an insulation enclosure  408 . The insulation enclosure  408  similarly defines a pocket  409  that has a depth that fully receives the battery  410 . The insulation enclosure  408  may be constructed of various materials such as Polyimide, PEEK, Polysulphone, LCP etc. 
         [0032]    As the battery  410  fits within the insulation enclosure  408  which then fits inside the outer enclosure  404 , the battery  410  is both housed in the separate enclosure configuration  402  while being electrically isolated from the outer enclosure  404  of the separate enclosure configuration  402 . Therefore, if the outer enclosure  404  is a conductor such as a biocompatible metal which is in contact with the body tissue and fluids, there will be no leakage of stimulation current directly back to the battery  410  because the insulation enclosure  408  provides the electrical isolation of the battery  410  from the outer enclosure  404 . 
         [0033]    Additionally, in this example, an adapter plate  406  and a top insulation layer  411  are provided. The top insulation layer  411  caps the top of the insulation enclosure  408  to electrically isolate the top of the battery  410  from the adapter plate  406 . The adapter plate  406  is attached to the top edge of the outer enclosure  404 , by a laser seam weld or similar manner of metal to metal connectivity to provide a hermetic seal, to fully enclose the insulation enclosure  408  and battery  410 . The adapter plate  406  is also laser seam welded or otherwise attached to the bottom edge of the housing  210  of  FIG. 2  to provide a hermetic seal to the housing  210 . 
         [0034]    In order for the battery terminal pins  412  to reach the stimulation circuitry  202 , the top insulation layer  411  includes holes  413  that allow the terminal pins to extend beyond the insulation enclosure  408 . The adapter plate  406  also includes one or more openings  407  that allow the terminal pins  412  to extend beyond the outer enclosure  404  and therefore exits the separate enclosure configuration  402  in order to extend into the housing  210  of the medical device  202 . 
         [0035]    The separate enclosure configuration  402  provides battery modularity while also electrically isolating the battery from the surrounding body tissues and fluid that are in contact with the exterior of the outer enclosure  404 . As the battery  410  is contained within the insulative enclosure  408 , the battery  410  is electrically isolated from the outer enclosure  404  so that the outer enclosure  404  may be constructed of an electrical conductor such as a biocompatible metal and the battery  410  remains electrically isolated from the body tissue and fluids. 
         [0036]      FIGS. 9, 10A, and 10B  show various views of a third example of a separate battery enclosure configuration  500 . In this embodiment an outer insulative enclosure  502  is created by being overmolded around the battery  504 . This outer insulative enclosure  502  may be constructed of various materials including biocompatible polymers such as PEEK, Polysulphone, LCP, Polyimide, Polyetherimide, etc. The outer insulative enclosure  502  fully encloses the battery  504  and because the outer insulative enclosure  502  is not an electrical conductor, the battery housing is electrically isolated from external conditions such as body fluids and tissue. Therefore, there will be no leakage of stimulation current directly back to the battery  504  because the insulation outer enclosure  502  provides the electrical isolation of the battery  504 . 
         [0037]    Additionally, in this example, an adapter plate  506  is provided. The adapter plate  506  is attached to the top edge of the outer insulation enclosure  502  to provide for attachment of the separate enclosure configuration  500  to the housing  210  of the medical device  202  of  FIG. 2 . The adapter plate  506  may be constructed of a biocompatible metal such as Titanium which allows the adapter plate  506  to be attached to the housing  210  by a laser seam weld or similar manner of metal to metal connectivity to provide a rigid connection and a hermetic seal. 
         [0038]    To provide a robust connection of the overmolded outer insulation enclosure  502  to the adapter plate  506 , the adapter plate  506  may include bores  508 . These bores  508  may have a countersunk configuration as shown in  FIG. 10A . When the overmolding about the battery is being performed to create the outer insulative enclosure  502 , the overmolding may also include causing the insulative material of the enclosure  502  to flow into the bores  508 . Once hardened, the insulative material of the enclosure  502  becomes rigidly connected to the adapter plate  506  via the presence within the bores  508 . 
         [0039]    In order for the battery terminal pins  510  to reach the stimulation circuitry  202 , the terminal pins  510  extend beyond the outer insulation enclosure  504  and also extend through and beyond the bores  508  of the adapter plate  506 . The overmolding of the insulation material surrounds the terminal pins  510  as they pass through and exit the bores  508 . The terminal pins  510  extend from the bores  508  into the housing  210  of the medical device  202 . 
         [0040]    Thus, the separate enclosure configuration  500  also provides battery modularity while also electrically isolating the battery from the surrounding body tissues and fluid that are in contact with the exterior of the outer enclosure  502 . There may be circumstances where the separate enclosure configuration  500  that lacks the conductive outer enclosure may be more appropriate than the examples above that use the conductive outer enclosure configuration. Examples of these circumstances include situations where device costs are a concern and the conductive outer enclosure is omitted, and/or where device longevity being decreased due to the lack of the conductive outer enclosure is not a concern. 
         [0041]    While embodiments have been particularly shown and described, it will be understood by those skilled in the art that various other changes in the form and details may be made therein without departing from the spirit and scope of the invention.