Abstract:
A flexible implantable electrical stimulator array is provided, which is associated with a flexible circuit board, biocompatible materials, a cathode electrode array and an anode electrode array. By using the flexible circuit board, the implanting position and implanting way of the present electrical stimulator are more flexible. Hence, the present electrical stimulator is more humanized and more widely used. Besides, by a design of electrode arrays, electrical treatment area is enlarged and electrical treatment efficiency is improved.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an implantable electrical stimulator, and more particularly to a flexible implantable electrical stimulator using a flexible circuit board. 
   2. Description of the Related Art 
   Electrical stimulator combines theories of Chinese traditional Point Percussion Therapy and TENS (Transcutaneous Electrical Nerve Stimulation) by using finite electrical current to stimulate particular points or muscles for reaching the effects of strong and health, that is, by using electrical current with proper frequency to stimulate nerves, muscles and cells continuously and gently, which can activate the self-recovering mechanism of body. There are two kinds of therapies clinically, TENS and EMS (Electrical Muscle Stimulation). 
   The electrical stimulators are widely used in rehabilitation, and due to the recent breakthrough of microelectronic technique, MEMS (Micro-Electro-Mechanical Systems), bio-material and biocompatible package technique, it makes electrical stimulators to be a miniature and implantable type. 
   A well-known electrical stimulator with biocompatible package encases all electrical components by a glass shell to prevent body fluid from infiltration. However, the glass package is a such hard package structure, if it is implanted into human&#39;s muscle structure, its metal materials therein will be directly contact with inner tissue of human body once it is broken due to the extrusion from muscular activities, and further releasing toxic materials, and can not achieve the purpose to be biocompatible. 
   SUMMARY OF THE INVENTION 
   It is one objective of the present invention to provide an implantable electrical stimulator employing a flexible circuit board to make the implanting position and implanting way of the present electrical stimulator more flexible. Hence, the present electrical stimulator is more humanized and more widely used. 
   It is a further objective of the present invention to provide an implantable electrical stimulator, which employs a design of electrode arrays to enlarge an electrical treatment area and improve electrical treatment efficiency. 
   It is another objective of the present invention to provide an implantable electrical stimulator, which employs flexible biocompatible package material to enhance safety, durability and reliability of the implantable electrical stimulator. 
   According to the above objectives, the present invention provides an implantable electrical stimulator, which includes: a flexible circuit board having a control circuit, a power supply circuit, a cathode conductive wire and an anode conductive wire, wherein the control circuit controls the power supply circuit to provide the cathode conductive wire and the anode conductive wire with a negative voltage and a positive voltage, respectively; a cathode electrode array having a plurality of cathode electrodes extending outward from one side of the cathode conductive wire; an anode electrode array having a plurality of anode electrodes extending outward from one side of the anode conductive wire; and a biocompatible polymer material covering the whole of the flexible circuit board and exposing portions of the cathode electrodes and the anode electrodes. 
   The present invention provides an implantable electrical stimulator combining a flexible circuit board, a flexible biocompatible package material and a design of electrode arrays to enlarge an electrical treatment area, improving electrical treatment efficiency, and making the implanting position and implanting way of the present electrical stimulator more flexible. Hence, the present electrical stimulator is more humanized, more widely used, and has enhancement of safety, durability and reliability after an implantable electrical stimulator is implanted to a human body. 
   The purposes and many advantages of the present invention are illustrated by detailed description of the embodiment, and become clearer understood with reference to accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1A  to  FIG. 1C  is schematic top views of various manufacturing stages of a flexible implantable electrical stimulator according to a first embodiment of the present invention. 
       FIG. 2  is a schematic top view of a flexible implantable electrical stimulator according to a second embodiment of the present invention. 
       FIG. 3  is a schematic top view of a variation of the first embodiment; and 
       FIG. 4  is a schematic top view of a variation of the second embodiment. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The present invention provides an implantable electrical stimulator employing a flexible circuit board, a flexible biocompatible package material to make the implanting position and implanting way of the present electrical stimulator more flexible, and it can naturally adjust appearance based on the shapes of muscular tissue, bones and organs, in addition, due to such flexibility it has, there is hardly a discomfort after implantation, and it is hardly affected by external percussion. On the other hand, the present invention employs a design of electrode arrays to enlarge an electrical treatment area and improve electrical treatment efficiency. 
   To be specific, the present invention uses the technology of Flexible Printed Circuit Board, FPCB, to manufacture a circuit board having a type of wireless transmission of energy, and buries easily-conductive parts likes legs of electrical components and conductive wires on a circuit board with black epoxy (Glass Transition Temperature, Tg&gt;60° C.) to enhance insulation, and then, uses biocompatible polymer material to cover the surface of a print circuit board and completes an implantable electrical stimulator of the present invention. 
   An implantable electrical stimulator of the present invention would be explained in detail by the following embodiments with reference to accompanying drawings. 
     FIG. 1A  to  FIG. 1C  is schematic top views of various manufacturing stages of a flexible implantable electrical stimulator according to a first embodiment of the present invention. See  FIG. 1A , firstly, to provide a flexible circuit board  10 , a flexible printed circuit board for example, which has a control circuit  101 , a power supply circuit  102 , a cathode conductive wire  103  and an anode conductive wire  104 . The flexible implantable electrical stimulator gains energy from external by employing the method of wireless transmission of energy, such as coil induction and antenna induction, to drive the control circuit  101 , and then, the control circuit  101  controls the power supply circuit  102  providing a negative voltage and a positive voltage to a cathode conductive wire  103  and an anode conductive wire  104 , respectively. A cathode electrode array  12  having a plurality of cathode electrodes  122  extending outward from one side of the cathode conductive wire  103 . An anode electrode array  14  having a plurality of anode electrode  142  extending outward from one side of the anode conductive wire  104 . 
   Then, see  FIG. 1B , to coat biocompatible conductive material, such as tantalum, stainless steel and titanium, on the extending parts of the cathode electrodes  122  and the anode electrode  142  from the flexible circuit board  10 . Then, see  FIG. 1C , using a biocompatible polymer layer  16  to cover the entire flexible circuit board  10 , and only expose parts of the cathode electrode array  12  and the anode electrode array  14 . The biocompatible polymer layer  16  can be silicone, PTMS (poly(tetramethylene succinaze)) and PMMA (poly(methylmethacrylaze)). Moreover, before using the biocompatible polymer layer  16  to cover the entire flexible circuit board  10 , black epoxy (Glass Transition Temperature Tg&gt;60° C.) can be used to bury electric components on the flexible circuit board, such as the connective legs of the electric components on the control circuit  101  and power supply circuit  102 , the cathode conductive wire  103  and the anode conductive wire  104 , to enhance insulation, and then biocompatible polymer layer  16  covers the entire flexible circuit board  10 . 
     FIG. 2  is a schematic top view of a flexible implantable electrical stimulator according to a second embodiment of the present invention. In the second embodiment, the circuits on the circuit board are integrated in a single chip by the way of Application Specific Integrated Circuit, ASIC. In other words, a flexible implantable electrical stimulator of the second embodiment comprises: a flexible circuit board  20  having an ASIC chip  202 , a cathode conductive wire  204  and an anode conductive wire  206 , wherein the ASIC chip provides a negative voltage and a positive voltage to the cathode conductive wire  204  and the anode conductive wire  206 , respectively; a cathode electrode array  22  having a plurality of cathode electrodes  222  extending outward from one side of the cathode conductive wire  204 ; an anode electrode array  24  having a plurality of anode electrode  242  extending outward from one side of the anode conductive wire  206 ; a biocompatible polymer layer  26  covering the entire flexible circuit board  20  and exposing portions of the cathode electrode array  22  and the anode electrode array  24 . The flexible circuit board  20  gains electric energy from the external by employing the method of wireless transmission of energy, such as coil induction and antenna induction, to drive the ASIC chip. Then, as the same as the first embodiment, before using the biocompatible polymer layer  26  to cover the entire flexible circuit board  20 , it can use black epoxy (Glass Transition Temperature Tg&gt;60° C.) to bury electric connective legs of the electric components on the flexible circuit board  20 , the cathode conductive wire  103  and the anode conductive wire  104 , to enhance insulation. Then, the extending parts of the cathode electrodes  222  and the anode electrodes  242  from the flexible circuit board  20  are coated with biocompatible conductive materials, such as tantalum, stainless steel and titanium. The flexible implantable electrical stimulator of the second embodiment integrated circuits on the flexible circuit board in a single ASIC chip, and it can be used by rolling up to minimize the space of an electrical stimulator occupying the human body. 
     FIG. 3  is a schematic top view of a variation of the first embodiment, the difference from the first embodiment is that a cathode electrode  122   a  and an anode electrode  142   a  replace the cathode electrode array  12  and the anode electrode array  14  of the first embodiment, respectively. That is, the flexible implantable electrical stimulator of the present invention shown in  FIG. 3  comprises a flexible circuit board  10   a , such as a flexible circuit board having a control circuit  101   a , a power supply circuit  102   a , a cathode electrode  122   a  extending outward from one side of the flexible circuit board  10   a  and an anode electrode  142   a  extending outward from the opposite side of the flexible circuit board  10   a . The flexible implantable electrical stimulator gains energy from external by employing the method of wireless transmission of energy, such as coil induction and antenna induction, to drive the control circuit  101   a , and then, the control circuit  101   a  controls the power supply circuit  102   a  providing a negative voltage and a positive voltage to the cathode electrode  122   a  and the anode electrode  142   a , respectively. 
   The extending parts of the cathode electrodes  122   a  and the anode electrodes  142   a  from the flexible circuit board  10   a  are coated with the biocompatible conductive material, such as tantalum, stainless steel and titanium. A biocompatible polymer layer  16  covers the entire flexible circuit board  10   a  and only exposes the portions of the cathode electrode array  122   a  and the anode electrode array  142   a . The biocompatible polymer layer  16  can be silicone, PTMS (poly(tetramethylene succinaze)) and PMMA (poly(methylmethacrylaze)). Moreover, before using biocompatible polymer layer  16   a  to cover the entire flexible circuit board  10   a , black epoxy (Glass Transition Temperature Tg&gt;60° C.) can bury electric components on the flexible circuit board  10   a , such as the connective legs of the electric components on the control circuit  101   a  and power supply circuit  102   a , the cathode electrode  122   a  and the anode electrode  142   a , to enhance insulation, and then the biocompatible polymer layer  16   a  covers the entire flexible circuit board  10   a.    
     FIG. 4  is a schematic top view of a variation of the second embodiment, the difference from the second embodiment is that a cathode electrode  222   a  and an anode electrode  242   a  replace the cathode electrode array  22  and the anode electrode array  24  of the second embodiment, respectively. That is, the flexible implantable electrical stimulator of the present invention shown in  FIG. 4  comprises a flexible circuit board  20   a  having an ASIC chip  202   a , a cathode electrode  222   a  extending outward from one side of the flexible circuit board  20   a  and an anode electrode  242   a  extending outward from the opposite side of the flexible circuit board  20   a . The ASIC chip  202   a  provides a negative voltage and a positive voltage to the cathode electrode  222   a  and the anode electrode  242   a , respectively. A biocompatible polymer layer  26  covers the entire flexible circuit board  20   a  to expose portions of the cathode electrode  222   a  and the anode electrode  242   a . The flexible circuit board  20   a  gains energy from external by employing the method of wireless transmission of energy, such as coil induction and antenna induction, to drive the ASIC chip  202   a . Then, as the same as the first embodiment, before using the biocompatible polymer layer  26   a  to cover the entire flexible circuit board  20   a , black epoxy (Glass Transition Temperature Tg&gt;60° C.) can bury connective legs of the electric components on the flexible circuit board  20   a , the partial cathode electrode  222   a  and the partial anode electrode  242   a , to enhance insulation. Then, the extending parts of the cathode electrodes  222   a  and the anode electrode  242   a  from the flexible circuit board  20   a  are coated with a biocompatible conductive material, such as tantalum, stainless steel and titanium. 
   The biocompatible materials using in the present invention meet the ISO 10993. 
   In conclusion, the present invention provides a kind of implantable electrical stimulator that is lighter, thinner, high circuit density, easy to process, low hygroscopic, high reliability, biocompatible, and providing enhancing electric-treatment. 
   Although the present invention has been described in considerable detail with reference to certain preferred embodiments thereof, those skilled in the art can easily understand that all kinds of alterations and changes can be made within the spirit and scope of the appended claims. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred embodiments contained herein.