Abstract:
A modular multi-channel inline connector system that connects an implanted electrode within a body of an organism, such as the human body, with a device located external to or implanted within the body. The modular multi-channel inline system comprises of a first lead operatively connected to the implanted electrode and to a first connector portion. A second lead is operatively connected to a second connector portion and operatively connected to the device. One of the first and second connector portions comprises a male connector and the other of the first and second connector portions comprises a female connector. The first and second connector portions are arranged to connect with each other and to be operatively located embedded within the body.

Description:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0001]    This invention was made with government support under Award or Contract No. N66001-12-C-4195 awarded by the Defense Advanced Research Projects Agency (DARPA). The government may have certain rights in the invention. 
     
    
     FIELD OF THE DISCLOSURE 
       [0002]    The present disclosure relates generally to a modular multi-channel inline connector system to link electrodes to percutaneous leads or an implanted electrical device within an organism, such as a human body. 
       BACKGROUND 
       [0003]    Neural interfaces technology is a rapidly growing segment of the medical device market. This technology mainly refers to devices that serve as an inter-connect between the stimulation/recording systems and the neuro-muscular tissue in the body. There currently are several known neuro-stimulation systems. Some notable neuro-stimulation systems include the cardiac pacemaker, cochlear implants, deep brain stimulation systems, spinal cord stimulation systems, gastric stimulation systems, vagal nerve stimulation systems, phrenic nerve stimulation systems, and others. Most of these systems include devices that are completely implantable into the human body, such as a patient. 
         [0004]    Although not as prevalent as the neuro-stimulation systems, there are many non-implantable recording systems that can be used to record muscle and neural activity to control prostheses. There are also experimental systems being developed for implantable muscle and neural recordings. 
         [0005]    In most of the neuro-stimulation/recording systems, it is common practice to test and calibrate the implanted electrodes, i.e., electrodes that are implanted into the body of the patient, prior to implanting the entire stimulator unit and/or recording unit into the patient&#39;s body. Specifically, the desired electrodes are first implanted at the target location in the patient&#39;s body and their efficacy is tested over a period of multiple days by using an external stimulator/recorder. After the trial period is over, if the electrodes function as intended, then the external connector is disconnected, and the leads are connected to an implantable stimulator/recorder that is programmed appropriately. On the other hand, if the electrodes do not function as intended, then only the electrodes need to be removed from the body instead of the whole implant. During the trial period, the leads from the implanted electrodes are connected to an external connector assembly through a percutaneous lead system. The stimulation/recording system plugs into the external connector assembly. In addition to being used during the trial period, the external connector assembly-percutaneous lead system can also be used to test novel electrode technology. This in particular usually requires the connector system to be functional for extended periods, such as from six months to one year. 
         [0006]    Unfortunately, most known commercial percutaneous systems in the market today suffer from one or more of the following limitations:
       a) they are often designed and used for a limited period, such as a trial period lasting over from two to seven days;   b) they often have high failure rates due to connector wear and tear, which is problematic because the electrodes will have to be replaced if the connector fails;   c) they often have high profile heights, particularly such systems that are designed for use as cranial implants; and/or   d) they are often not easily expandable.       
 
         [0011]    Although multiple versions of inline connector and percutaneous systems have been developed and patented previously, none of them have a complete modular structure as the one presented in this document. 
         [0012]    Hence a need exists to develop a modular, convenient and reliable connector system to link the stimulation/recording system (external non-implanted or internal implanted) to implanted electrodes. In one or more preferred forms, it would also be preferable that the connector system satisfy any one or more of the following conditions:
       a) it may be designed to minimize trauma to the patient both from the surgical installation procedure and also from the day-to-day use;   b) all or at some parts of the connector system (external, internal and percutaneous section) may be designed so as to minimize the possibility of infection;   c) parts subject to wear and tear may be designed to be easily replaceable without need for surgical intervention;   d) external components may be designed to have a low profile height and should also occupy minimal footprint on the skin to minimize skin abrasions;   e) it may be designed to be easily expandable to accommodate additional electrodes; and/or   f) it may be designed to be modular to allow electrodes to be connected to either an external or an internal stimulation/recording system.       
 
       SUMMARY 
       [0019]    According to some preferred aspects of the present disclosure, a connector assembly according to the teachings of the present disclosure optionally has a modular design. In some arrangements, this provides versatility to switch from a system architecture that has percutaneous leads to a system architecture with implanted electronics while being able to keep the same set of electrode contacts in place in the patient&#39;s body. In some arrangements, the modularity provides the ability to expand system capacity by adding more multi-channel electrodes to either the external connector system or the implanted electronics. 
         [0020]    According to some preferred aspects of the present disclosure, the external connector assembly optionally is replaceable. In some arrangements, the percutaneous leads are detachable from the external connector assembly. In this embodiment, if the multi-pin connector on the external connector were to go bad, then the whole external connector assembly can be replaced without altering the implanted electrode contacts or the percutaneous leads. 
         [0021]    According to some preferred aspects of the present disclosure, the external connector assembly optionally has a very low profile. In some arrangements, the whole assembly is made out of a flexible material so as to conform to the skin. 
         [0022]    According to some preferred aspects of the present disclosure, the external connector setup may be easily expandable. For example, if additional electrodes need to be implanted in the nerve, then the current multi-pin connector assembly can be replaced with a new connector assembly box with more slots and a higher count multi-pin connector. This allows the current electrodes as well as the new set of electrodes to be used. 
         [0023]    According to some preferred aspects of the present disclosure, the external connector configuration optionally greatly increases the number of connector mating cycles before system failure. In general, the smaller connectors tend to have limited mating cycle life. However, the modular structure according to the teachings of the present disclosure, in some arrangements, helps in compounding the mating life cycle. For example, if the proximal lead has a life of 100 mating cycles and the multi-pin commercial connector has a mating life of 500, then in theory, the whole ensemble could have a mating life of 50000 cycles. 
         [0024]    According to some preferred aspects of the present disclosure, the inline connector system optionally has a very low profile. Existing technology for multi-channel systems either uses bulky multi-contact inline connectors or multiple single-contact inline connectors. In contrast, the inline connector system according to the teachings of the present disclosure, in some arrangements, has a much smaller profile. 
         [0025]    According to some preferred aspects of the present disclosure, one end of the inline connector system optionally can be hardwired to multiple fine wires that are suitable for implantation directly into nerve fascicles. In contrast, existing technology for multi-channel systems use wires with diameters and materials that are not suitable for direct insertion into nerve fascicles. 
         [0026]    Additional optional aspects and forms are disclosed, which may be arranged in any functionally appropriate manner, either alone or in any functionally viable combination, consistent with the teachings of the disclosure. These and other aspects and advantages will become apparent upon consideration of the following detailed description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]      FIG. 1  shows components of an exemplary electrode and connector system according to the teachings of the present disclosure. 
           [0028]      FIG. 2  is a schematic view of an exemplary external connector assembly according to the teachings of the present disclosure. 
           [0029]      FIG. 3  is a schematic view of the external connector assembly according to the teachings of the present disclosure. 
           [0030]      FIG. 4  is a schematic of a printed circuit board with contact pins soldered onto it according to the teachings of the present disclosure. 
           [0031]      FIG. 5  is a schematic view of a proximal connector on a percutaneous lead according to the teachings of the present disclosure. 
           [0032]      FIG. 6  is a schematic view of the inline connection between the percutaneous lead and an implanted lead according to the teachings of the present disclosure. 
           [0033]      FIG. 7  is a schematic view of a male connector on the distal end of the implanted lead according to the teachings of the present disclosure. 
           [0034]      FIG. 8  is an isometric view of the male connector on the implanted lead according to the teachings of the present disclosure. 
           [0035]      FIG. 9  is a cross-sectional view of the male connector of  FIG. 8  showing the contact point according to the teachings of the present disclosure. 
           [0036]      FIG. 10  is a schematic view showing a female connector on the distal end of the percutaneous lead according to the teachings of the present disclosure. 
           [0037]      FIG. 11  is a schematic of the inline connector system of  FIG. 2  in another arrangement including a ground electrode embedded inside the body. 
       
    
    
     DETAILED DESCRIPTION 
       [0038]    For the purpose of this disclosure, the term external shall refer to devices/components outside the body and the term implanted shall refer to devices/components installed inside the body. 
         [0039]    In this disclosure, the connector system is explained for use with neural interfaces. However, the technology disclosed herein can be used in any application in which electrical or optical signals need to be transferred between a device outside the skin, i.e. external, to an implanted system (e.g. electrical/optical signal to activate an implanted system for targeted drug delivery). 
         [0040]    The connector system design of this disclosure is described assuming longitudinal-intrafascicular electrodes (LIFE) implanted in the fascicles of the peripheral nerve. As such, the same design can be used to connect to any neural electrode such as Utah electrode array, cuff-electrode, tf-LIFE, etc., connected to nerves or other excitable tissue inside the body. 
         [0041]      FIG. 1  shows high level schematic views of two system architectures of a modular multi-channel inline connector system for the technology of the present disclosure. One version is a multi-channel system  1  that uses an inline connector  3  to percutaneous leads  4  to link implanted electrode contacts  5  to external components  5   a . The other version is a multi-channel system  2  that uses an inline connector  3  to link implanted electrode contacts  5  to an implanted device  6  that communicates (via RF or other transcutaneous link) to external components  7 . 
         [0042]    This presents a versatile system to transfer electrical activity between a device (in or out of the body) to a set of one or more electrodes implanted in tissue or other body organs from which electrical/optical activity can be recorded or stimulated. 
         [0043]    As seen in  FIG. 1 , in a multi-channel system  1  with percutaneous leads, the connector has four parts: an external connector assembly  8 , one or more percutaneous leads  4 , one or more implanted leads  9 , and an inline connection  3 . The external connector assembly  8  serves to link the percutaneous lead(s)  4  with external equipment  5   a , such as a stimulator or amplifier/recorder. The percutaneous lead(s)  4  have a multi-contact external connector on one end and an implantable multi-contact connector on the other. One connector could have one or more percutaneous leads. In the embodiment shown in  FIG. 2 , there is a multi-contact male connector  10  on the proximal end (external) and a female inline connector  11  on the distal (implanted) end, as shown in detail in  FIGS. 5-10 . The implanted leads  9  include a multi-contact connector  25  on one end and electrodes  5  on the other end. The inline connection  3  is the implantable multi-contact connection between implanted lead  9  and an extension (that may or may not be percutaneous) of the percutaneous lead  4 . The connector setup will have as many inline connections as there are percutaneous leads  4 . In the embodiment shown, the inline connection  3  is used to link the implanted lead  9  to the distal end of the percutaneous lead  4  inside the body. 
         [0044]    In a multi-channel system  2  without percutaneous leads, the external connector assembly  8  and the percutaneous leads  4  are replaced by the implanted device  6 . The implanted device  6  has multiple ports or docks for the multi-contact electrode leads similar to those described in U.S. Pat. No. 7,236,834, which is incorporated by reference in its entirety herein. 
         [0045]      FIG. 2  shows a more detailed schematic of the entire electrode-connector system of  FIG. 1  with implanted and external parts including an embodiment with percutaneous leads, corresponding to the system  1 . Each part of this embodiment of the connector system  1  shown in  FIG. 2  is explained in detail hereinafter with reference to  FIGS. 3-10 . 
         [0046]      FIG. 3  shows a schematic of an external connector assembly  8  of  FIG. 2 . along with the mating percutaneous leads  4 . The external connector assembly  8  includes a central core  12  covered by an outer shell (not shown in  FIG. 3 ). The central core  12  is made up of a printed circuit board (PCB)  13 , which may be flexible or other, with a multi-pin connector  14 , such as a Micro PSM Series 32-pin female connector from Omnetics, on one end. The other end  15  has multiple columns of contacts  16  molded into slots  17  as shown in the schematic. The connections between the multi-pin connector  14  and the contacts are made on the PCB  13 . 
         [0047]      FIG. 4  shows a schematic of just the PCB  13  of  FIG. 3  with contact pins  18  and the multi-pin connector  14  soldered to it. As seen in  FIG. 4 , the contact pins  18  are bent inward to ensure good contact with the proximal end  19  of the percutaneous lead  4 . 
         [0048]    The PCB  13  can be made of FR4 material and is RoHS compliant. A preferred thickness of the PCB  13  is about 787 μm. The contact pins  18  are typically made of stainless steel, nickel-plated stainless steel, gold-plated beryllium copper, titanium, tantalum or noble metals such as platinum or platinum/iridium. The contact pins  18  are preferably soldered onto the board  13  using lead-free solder. Alternatively, the contact pins  18  can also be welded to the pads on the PCB. The plastic mold preferably is an electrical insulator. It is preferably made out of a bio-compatible material such as urethane, silicone, polytetrafluroethylene (PTFE), epoxy, poly-sulphone or similar materials. The top and bottom lids of the outer shell can also be made of material listed above. The lids can either be screwed into the molded plastic or slid into a groove in the molded plastic. 
         [0049]      FIG. 5  shows a schematic of the proximal end (external)  19  of the percutaneous lead  4 . The body  24  of the proximal lead  4  includes an outer tube  20  with an outer diameter between 1.8 mm to 2 mm and an inner diameter of between 1.2 mm to 1.5 mm. The body includes grooves  22  to fit the contact pins  21  as shown in  FIG. 5 . The contact pins  21  are manufactured separately and can be positioned in the grooves  22  by pushing the contact pins  21  onto the grooves  22 . The contact pin  21  preferably fits in snuggly with the groove  22 . Additionally one could also glue the contact pins  21  to the grooves  22  using a medical grade adhesive. Each contact pin  21  is soldered to a lead wire  23  which extends out of the lead body  24  through a hollow channel  25  at the center as shown in  FIG. 5 . Finally the body  24  of the lead is sealed on the top side ( FIG. 5  shows the top view without the top lid  35 ) by gluing a plastic lid  35 , preferably to the body  24 . 
         [0050]    The contact pins  21  are preferably made of stainless steel, nickel-plated stainless steel, gold-plated beryllium copper, titanium, tantalum or noble metals such as platinum or platinum/iridium. The contact pins  21  preferably are soldered onto the board using lead-free solder. Alternatively, the contact pin  21  can also be welded to the pads on the PCB. The body  24  preferably is a plastic mold and preferably is an electrical insulator. The body  24  is preferably made out of a biocompatible material such as urethane, silicone, polytetrafluroethylene (PTFE), epoxy, poly-sulphone or similar materials. The wires  23  in the lead  4  can be made of any biocompatible material such as stainless steel, platinum, platinum-iridium. Each wire  23  preferably is insulated using biocompatible material such as PTFE or PFA. The ensheathing tube (outer tube)  20  is preferably made of a medical grade tubing material, such as silicone. 
         [0051]    Each proximal end  19  of the percutaneous lead  4  is mated with the external connector assembly  8  by lining the lead  4  directly on top of the slot  17  such that the “alignment grooves”  22  line up, and then by pushing it down. Once all the leads  4  are placed in the slots  17 , the top lid  35  is screwed in. The grooves  22  on the lead  4  prevent the lead from sliding out of the slot  17  horizontally. The top lid  35  holds the lead  4  in place in the slot  17  from the top. 
         [0052]      FIG. 6  contains a schematic showing the inline connection  3  between the implanted lead  9  and the percutaneous lead  4 , including a male connector  25  and a female connector  11 . The implanted lead  9  has LIFE wires  26  on one end and a male connector lead  25  on the other end. As mentioned previously, the percutaneous lead  4  has a male connector  10  external to the body and a female hollow connector  11  inside the body. Subsequent paragraphs provide a short description of optional arrangements for the male and female parts  25 ,  11  of the inline connection  3 . 
         [0053]      FIG. 7  contains a schematic of the male end  25  of the connector  3 . The design for this connector is the same as the proximal end  19  of the percutaneous lead  4  except for the alignment groove  32  on top. In case of LIFE electrodes, the Pt-Ir LIFE wires are soldered/welded directly onto the contact as explained previously. Additionally, all the materials used in this case are preferably implant grade.  FIG. 8  contains an isometric view of the male connector lead  25  and  FIG. 9  shows the cross sectional view of the same. 
         [0054]      FIG. 10  contains a schematic showing the side, cross-sectional view of the female connector  11 . The female connector  11  includes a hollow tube, with pins  27  attached on the top. The percutaneous lead wires  23  are soldered to individual pins  27  and the connector body  26  is molded around it by using the pins  27  as an insert in the mold. The tapered end  28  provides strain relief. The body  26  also has threaded screw holes  29  on the bottom side as seen in  FIG. 10 . The screw holes  29  aid in guiding the male lead as it is inserted. 
         [0055]    To mate and secure the male lead  25  to the female lead  11 , the male lead  25  is inserted all the way into the female lead  11 , and the female lead  11  is screwed with anchor screws  31  in to make a tight, sealed contact. 
         [0056]    The contact pins  27  are preferably made of stainless steel, nickel-plated stainless steel, titanium, or noble metals such as platinum or platinum/iridium. The plastic mold forming the body  26  is preferably an electrical insulator. The plastic mold forming the body  26  may be made out of a bio-compatible material such as urethane, silicone, polytetrafluroethylene (PTFE), epoxy, poly-sulphone or similar materials. Both the male and female leads  25 ,  11  are lined with silicone pads (isolation pads)  30  to prevent body fluids from entering the connector  3  and shorting the leads  9 ,  4 . 
         [0057]      FIG. 11  shows the multi-channel system  1  arranged with a ground electrode  36  connected by a percutaneous lead  4  to the external connector assembly  8 . Further, the implanted lead  9  includes a plurality of different parallel lead portions  9   a ,  9   b . At one end of the lead  9 , the lead portions  9   a ,  9   b  are bundled together in a single bundle. The bundle is connected to the inline connector  3 . At the other end of the lead  9 , the lead portions  9   a ,  9   b  are separated so as to be able to connect different electrode contacts  5  to different spaced apart regions, such as different and/or spaced apart nerve and/or muscle groups. 
         [0058]    In general terms, a system according to the teachings of the present disclosure can be used in any application where electrical signals need to be passed between an external system and implanted leads inside a human body. Specifically, this system can be used in electrical/optical stimulation/recording applications. 
         [0059]    In some arrangements, the connector system is completely modular and easily expandable. These characteristics allow long term device trialing without causing significant discomfort, or at least reduced discomfort, to a patient in comparison with previous connector systems. 
         [0060]    In some arrangements, a connector system according to the present teachings provides an external connector with a significantly lower profile. The external connector in some arrangements is made of flexible material that can conform to the skin of the patient. 
         [0061]    In some arrangements, the in-line lead system is significantly smaller than alternative lead systems currently available. In some arrangements, the in-line lead system has between 10 and 50 contacts, and preferably between 22 and 32 contacts. 
         [0062]    The connector system preferably can be used as an interface between any known medical external electrical stimulation and/or recording system and any medical implanted neural and/or muscular electrodes.