CA1083676A - Implantable electric terminal for organic tissue - Google Patents
Implantable electric terminal for organic tissueInfo
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- CA1083676A CA1083676A CA270,034A CA270034A CA1083676A CA 1083676 A CA1083676 A CA 1083676A CA 270034 A CA270034 A CA 270034A CA 1083676 A CA1083676 A CA 1083676A
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- electric terminal
- porous
- tissue
- terminal according
- electrically conductive
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Abstract
ABSTRACT OF THE DISCLOSURE
A non-reacting implantable electric terminal for organic tissue, which is porous and intermeshes with the tissue including blood capillaries without the formation of a fibrous tissue encapsulation that reduces the sensitivity of tissue to electricity. This electric terminal is composed of tissue-compatible implantable material or materials at least one of which Is electrically conductive, such as platinum, or an alloy, and which has on at least one surface thereof a porous material or layer having pores that are Interconnected and continuous so that body electrolytes and/or tissue containing blood capillaries can contact the electrically conductive material through said porous material or layer. The pores of this material or layer also must have an average diameter sufficient to permit blood vessels to form in them, i. e.
a diameter preferably between about 10 and 500 microns. This porous material may be either electrically conductive or electrically non-conductive, and may comprise a porous metal, carbon, ceramic, such as one containing aluminum oxide, and/or a synthetic polymer, or elastomer, such as one containing a silicone, a fluorocarbon, or an epoxy resin. The shape of the electric terminal may vary as desired, and the more interconnected pores it contains the better.
This electric terminal may either be placed on the surface of the tissue like a plate or disk, or be inserted into the tissue.
A non-reacting implantable electric terminal for organic tissue, which is porous and intermeshes with the tissue including blood capillaries without the formation of a fibrous tissue encapsulation that reduces the sensitivity of tissue to electricity. This electric terminal is composed of tissue-compatible implantable material or materials at least one of which Is electrically conductive, such as platinum, or an alloy, and which has on at least one surface thereof a porous material or layer having pores that are Interconnected and continuous so that body electrolytes and/or tissue containing blood capillaries can contact the electrically conductive material through said porous material or layer. The pores of this material or layer also must have an average diameter sufficient to permit blood vessels to form in them, i. e.
a diameter preferably between about 10 and 500 microns. This porous material may be either electrically conductive or electrically non-conductive, and may comprise a porous metal, carbon, ceramic, such as one containing aluminum oxide, and/or a synthetic polymer, or elastomer, such as one containing a silicone, a fluorocarbon, or an epoxy resin. The shape of the electric terminal may vary as desired, and the more interconnected pores it contains the better.
This electric terminal may either be placed on the surface of the tissue like a plate or disk, or be inserted into the tissue.
Description
~83;~
BACKG~OUND OF THE INVENTION
When inert foreign bodies such as metals, ceramics~ plastics~ or the like, are implanted or contacted with living tissue, such as in an animal or the human body, the living tissue builds up a defensive Fibrosis around this body in an e-Ffort to reject~ insulate and isolate it from the vascularized tissue.
In the case of electric terminals or electrodes, particularly those For stimula-tion for heartpacers as described in applicantls United States Patent No.
3,659, 615, issued May 2, 1972, its metal electrodes puncture the myocardium -and soon become coated with fibrous tissue reducing the electrical conductivity 10 i nto the muscl e.
L. W. Smith et al in their United States Patent No. 3,31~,420 issued April 1~, 1967 disclosed a porous ceramic material as a bone substitute into which body tissue grows.
F. W Rhinelander et al in their article entitled "Microvascular and Histogenic Responses to Implantation of a Porous Ceramic into Bone~ published in J. Biomed. Mater. Res. Vol. 5 pp 81-112 ~1971) disclosed that bone tissue containing blood capillaries grew deep into and intermeshed with the porous ceramic materials patented by Smith et al. Furthermore, S. F. Hulbert et al -in their article entitled ~Compatibility of Porous Ceramic With Soft Tissue;~
.j ::~
20 Application to Tracheal Prothesis" published in J. Biomed. Mater. Res.
Symposium Vol. 2 (part 1) pp 267-279 (1971) disclosed that soft tissue contain- ~ I
`~ ing blood capillaries also grew deep into the interconnecting pores of porous ceramics.
R. B. Beard et al in their article entitled ~Porous Cathodes for Implantable Hybrid Cells~' published in the 1. E. E. E. Transaction on Biomedical ;
Engineering, Vol. 19, No. 3, May 1972, disclosed that porous platinum and palladium black ca~alystic electrodes for power generation when implanted in soft tissue produced a surrounding tissue capsule having apparent revasculari-` zation in said capsule, and that there were some apparent tissue ingrowth into ~ c~f~/y ~,'c :
30~a the pores oF the electrodes which caused poisoning of its ~a~~6 effect.
Furthermore, the formation of a granulated or fibrous tissue around implanted active porous electrodes, such as For fuel cells, was disclosed into the Dral<e ;
et al article entitled ~'A Tissue Implantable Fuel Cells Power Supply~ published . -inVol. XVI Trans. ~ctions American Soc. ~rtif. Int. Organs 1970 pp~,9~-205. ~
. ~ .
~ 33~;76 Accordingly, the problem was to produce a non-reacting implantable electric terminal without the formation of a fibrous tissue coating.
SUMMARY OF THE I NVENT ION
Generally speaking the non-reacting implantable electric terminal of this invention comprises a substrate of an electrically conductive porous or non-porous material, such as metal in the form of a flat disk or a wire or other shape, to which is ineimately attached an inert non-absorbable porous material, such as a layer, either of the same or of a different composition which may be an electrically conductive or an electrically non-conductive porous material, such as a metal, carbon, ceramic, metal plated ceramic, plastic, metal plated plastic, or a combination thereof. This porous material is provided with sufficient pores so that at least some of them are inter-connected and continuous throughout its thickness to the elecfrically conduc~tive material or part of this electric terminal. These pores are of a sufficient sizeso as to permit blood vessels to form in them from the tissue on or in which the porous material is implanted, but small enough to prevent the formation of fibrosis therein. Also these pores must permit the body electrolytes to fill these passages for conducting the electricity from the electrically conductive part of this electric terminal into the tissue.
The electrically conductive material or substrate of this electric terminal preferably is an inert porous or non-porous material and must be compatible to the body tissue and body fluids in which it is implanted. Such ;` ~ materials include~ for example: platinum~ iridium~ niobium, indium~titanium, tantalum7 vanadium~ tungsten~ chromium~ cobalt~ stainless steel~
an alloy of some of these metals called Vitallium or Elgiloy~ carbon, or the like. These materials may be formed into various shapes for intimate contact or implantation in or onto the particular tissue which is to be stimulated or sensed.
The porous layer or coating on the electrically conductive part of this electric terminal occurs at least upon the surface which is in contact with the tissue to be sensed or stimulated, and preferably all of its surface not to be electrically insulated from the tissue. This porous layer may comprise either a porous layer of the same or other electrically conductive material, or may comprise a coating of a non-electrically conductive porous r ~ -2-~383~
material. These porous materials may range from 5% to 85% porous in which a sufficient number of the pores interconnect and are continuous so that the layer is easily permeable to the electrolytes in the organic tissue.
The size of the pores may vary anywhere between about 0. 5 microns in diameter up to about lO00 microns, however, it has been found that pores whose average diameters fall within the range of about 10 and 500 microns are most satisfactory. The pore sizes must be sufficient for the blood vessels and tissue to grow into them for better intimate contact with the tissue to be electrically sensed or stimulated.
IF this porous layer is of an electrically conductive material, it may be of metal, carbon, a metal plated or coated non-conductive material, an electrically conductive plastic which may contain metal, and/or carbon, or it may be same material as the substrate oF the electric terminal. These ~ ;
electrically conductive materials also may be combined with a ceramic to Form a porous permeable layer of the implantable electric terminal of this invention.If this porous kayer is of an electrically non-conductive material, it may be of a ceramic or metallic oxide, such as aluminum oxide, silicon dioxide, -~
or either or both of these oxides together with calcium, magnesium, titanium and/or zirconium oxides, or a porous ceramic of such oxides callecl Cerosium.
This porous layer also may comprise a plastic material, such as a natural or synthetic polymer or elastomer, such as fclr example a silicone, a fluorocarbon, an epoxy resin, nylon, a rubber, polyurethane, polyethylene, polypropylene, polycarbonate, or mixtures thereof preferably that are :
compatible with and implantable into organic tissues and fluids. These plastics also may be combined with a ceramic to form the porous permeable layer of the ; implanted electric terminal of this invention.
If the only electrical contact with the electric terminal is at the end of the continuous pores in the electrical non-conductive coating layer, the current density is greater for that electric terminal than it would be if its core or electrical conductive part were also porous, and/or iF the porous coating layer were also electrically conductive, such as being made out of an electrically conductive porous material or out oF an electrically non-conductiveporous material coated or plated with an electrically conductive material, such as a non-reacting metal.
~133~7~
The implantable electric terminals of this invention are effective for use as sensors and/or stimulators For the heart, for the bladder, the pancreas, the central nervous system, the carotid sinus, the lungs, For bone healing, for pain control stimulators, and the like.
Accordingly, it is an object of this invention to produce an implant-able electric terminal for organic tissue which intermeshes with the tissue, and permits ingress of blood vessels without the production of a fibrous tissue interface that increases the stimulating threshhold level.
Another object is to control the current density of an implantable electric terminal by increasing or decreasing the conductive surface area of such a terminal.
A principal object of the invention is to provide a non-reactîng impantable electric terminal for an organic tissue comprising: an electrically conductive portion having a surface thereof adapted to contact tissue electro-lyte, said surface being completely surrounded and in intimate contact with an ~ "
inert, non-absorbable porous material having interconnected and continuous pores of an average diameter of between 10 and 500 microns so as to permit ingress of blood capillaries and intermeshing with said tissue without the forma- -tion of a fibrous tissue interface adjacent said surrounding part, and to permitelectrolytes in the tissue to pass therethrough and to be in continious contact with said electrically conductive portion, and means for connecting the electri-cally conductive portion of said electric terminal to an electrical circuit means.
The above mentioned and other features~ objects and advantages~
; and a manner of obtaining them are described more specifically below by reference to embodiments of this invention shown in the accompanying drawings9 wherein:
Figure I is an enlarged perspective view of one embodiment of an electric terminal according to this invention, comprising a disk implanted on the surface of the tissue to be sensed or stimulated;
Figure ll is a further enlarged section taken along line ll - ll of Figure I showing the separate electrically conductive and electrically non-conductive parts of this electric terminal;
Figure lll is an enlarged side view of a helical shaped electric terminal for insertion in a tissue, which terminal has a porous coating thereon;
~33~t'l6 Figure IV is a further enlarged section taken along line IV - IV of Figure lll showing the porous coating surrounding the central electrically con-ductive part of the electric terminal;
Figure V is a section similar to Figure IV of another embodiment oF
this invention, in which the central electrically conductive part is porous also;
Figure Vl is a section similar to Figure IV of a further embodiment -~
of this invention in which the electrically non-conductive porous layer is plated with an electrically conductive material; and Figure Vll is a section similar to Figure IV of still another embodi-10 ment of this invention, in which the outer porous portion is of the same electri-cally conductive material as the substrate.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Referring first to l=igures I and ll, there is shown a disk-shaped t electric terminal 10 implanted on organic tissue T, such as an epicardium.
This electric terminal 10 is shown to have an electrically conductive metallic substrate or disk portion 12 into which may be axially threaded or soldered a similar metal conductor rod or wire 14 connected to an electrical sensor or stimulator circuit means 15 to which another electrode 10 by means of a con-ductor 14 is also connected to another portion of tissue T in the same body.
20 On at least one of the flat surfaces 16 of the disk portion 12, and herein shown also around the periphery of the disk portion 12, is a layer of porous material 20. This porous material 20 is shown to be an electrically non-conductive ceramic material; such as aluminum oxide, containing a plurality of inter-connected and continuous pores 22. Thus pores 22 fill with body electrolytes for conducting electricity between the disk 12 and the tissue T. A~so into these pores 22 grow the blood capillaries C from the tissue T upon which the surface 24 of the disk 20 is intimately placed. This porous ceramic part 20 may be separately formed and then attached to the disk 12, or it may be sintered or integrally formed onto the disk 12.
Although this electric terminal 10 may be used either for electrically ; stimulating or sensing the tissue T, this electricity reaches the electrically conductive part 12 of this electric terminal 10 through the electrolyte in the pores 22 from the tissue T~ and thence is conducted through the conductor or wire 14 out to the instrument 15 that generates or senses this electricity.
,.
~3~76 Referrin~ now to the embodiment shown in Figures lll and IV~ the electrically conductive material or central wire portion 32 of the electric terminal 30 has an electrically non-conductive porous material coating or layer 40 thereon. This layer 40 may be separately formed and then a wire or post, such as the helical wire 32 threaded therein, or the porous layer 40 may be sintered or integrally formed onto the electrically conductive part 32. This porous layer 40 also has pores 42 that interconnect and are continuous so as to be permeable to body or tissue liquids from its outer surFace inwardly to the electrically conductive part 32.
In the above described embodiments, the current density of the electric terminal 10 or 30 is relatively high since the only electrically conduc-tive contact between the electrically conductive material 12 or 32 of the terminai is where the continuous pores 22 or ~2 through the outer electrically non-conductive part open onto the outer surface 16 of the disk 12 or onto the outer surFace of the center wire 32 for direct contact with the body electrolytes.
In order to decrease this current density or increase the surface area of the electric terminal of this invention for contact with the body electrolytes in the body tissue T, the center electrically conductive part may be made porous also as shown in Figure V, or the porous surrounding ;layer may be made of an electrically conductive material by being plated with a metal as shown in Figure Vl, or be made of an electrically conductive material different from or the same as or integrally with the center part as shown in Figure Vll.
Specifically, Figure V shows a cross-seGtion of an electric lerminal 50 having an electricaily non-conductive outer layer 60 with pores 62 and a center electrically conductive part 52 with pores 54 which fill with electrolyte from the tissue which passes through the pores 62.
Instead o-F or to3~i~ with the embodiment shown in Figure V, the outer porous layer 80 (see Figure Vl) of an implantable electric terminal 70 may be plated with a non reacting metal or electrically conductive material 84 which plating also coats the surfaces of the continuous pores 82 so as to be in electrical contact with the electrically conductive center part 72, thereby increasing the current density of the electric terminal over that described in Figures ll and lll.
Rather than plating the electrically non-conductive porous layer of : -6-~ 336~76 the electric terminal of this invention, this whole porous layer may be made of an electrically conductive material of a different or the same composition as the electrically conductive center part; including forming the whole electric terminal ;
out of the same material as shown in Figure Vll for the electric terminal 90 having an outer layer 100 with interconnected and continuous pores 102, and a center part 92, which center part may also be porous as shown in the embodi ment of F i gure V.
It is to be understood that other shapes of the implantation electric terminals oF this invention can be made embodying tissue compatible electrically ;
10 conductive material having a porous layer thereon, which layer may be either separate or of the same material as the electrically conductive substrate of the electric terminal. Thus the disk shaped electric terminal 10 as shown in the embodiment in Figures I and ll may have its porous disk part 20 formed of an electrically conductive material, such as shown in the embodiments of Figures V, Vl and/or Vll~ without departing from the scope of this invention.
Furthermore, the thickness of the porous layer may vary as desired, however, generally the dimensions of the electric terminal shown in Figures I
and ll have as their largest dimension about one centimeter, and as their smallest dimension~ i. e. their thickness preferably less than about one quarter 20 of a centimeter.
While there is described above the principles of this invention in connection with specific apparati, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of th i s i nven t i on .
` .
/
.. , .. . ,, ., ~ ..
BACKG~OUND OF THE INVENTION
When inert foreign bodies such as metals, ceramics~ plastics~ or the like, are implanted or contacted with living tissue, such as in an animal or the human body, the living tissue builds up a defensive Fibrosis around this body in an e-Ffort to reject~ insulate and isolate it from the vascularized tissue.
In the case of electric terminals or electrodes, particularly those For stimula-tion for heartpacers as described in applicantls United States Patent No.
3,659, 615, issued May 2, 1972, its metal electrodes puncture the myocardium -and soon become coated with fibrous tissue reducing the electrical conductivity 10 i nto the muscl e.
L. W. Smith et al in their United States Patent No. 3,31~,420 issued April 1~, 1967 disclosed a porous ceramic material as a bone substitute into which body tissue grows.
F. W Rhinelander et al in their article entitled "Microvascular and Histogenic Responses to Implantation of a Porous Ceramic into Bone~ published in J. Biomed. Mater. Res. Vol. 5 pp 81-112 ~1971) disclosed that bone tissue containing blood capillaries grew deep into and intermeshed with the porous ceramic materials patented by Smith et al. Furthermore, S. F. Hulbert et al -in their article entitled ~Compatibility of Porous Ceramic With Soft Tissue;~
.j ::~
20 Application to Tracheal Prothesis" published in J. Biomed. Mater. Res.
Symposium Vol. 2 (part 1) pp 267-279 (1971) disclosed that soft tissue contain- ~ I
`~ ing blood capillaries also grew deep into the interconnecting pores of porous ceramics.
R. B. Beard et al in their article entitled ~Porous Cathodes for Implantable Hybrid Cells~' published in the 1. E. E. E. Transaction on Biomedical ;
Engineering, Vol. 19, No. 3, May 1972, disclosed that porous platinum and palladium black ca~alystic electrodes for power generation when implanted in soft tissue produced a surrounding tissue capsule having apparent revasculari-` zation in said capsule, and that there were some apparent tissue ingrowth into ~ c~f~/y ~,'c :
30~a the pores oF the electrodes which caused poisoning of its ~a~~6 effect.
Furthermore, the formation of a granulated or fibrous tissue around implanted active porous electrodes, such as For fuel cells, was disclosed into the Dral<e ;
et al article entitled ~'A Tissue Implantable Fuel Cells Power Supply~ published . -inVol. XVI Trans. ~ctions American Soc. ~rtif. Int. Organs 1970 pp~,9~-205. ~
. ~ .
~ 33~;76 Accordingly, the problem was to produce a non-reacting implantable electric terminal without the formation of a fibrous tissue coating.
SUMMARY OF THE I NVENT ION
Generally speaking the non-reacting implantable electric terminal of this invention comprises a substrate of an electrically conductive porous or non-porous material, such as metal in the form of a flat disk or a wire or other shape, to which is ineimately attached an inert non-absorbable porous material, such as a layer, either of the same or of a different composition which may be an electrically conductive or an electrically non-conductive porous material, such as a metal, carbon, ceramic, metal plated ceramic, plastic, metal plated plastic, or a combination thereof. This porous material is provided with sufficient pores so that at least some of them are inter-connected and continuous throughout its thickness to the elecfrically conduc~tive material or part of this electric terminal. These pores are of a sufficient sizeso as to permit blood vessels to form in them from the tissue on or in which the porous material is implanted, but small enough to prevent the formation of fibrosis therein. Also these pores must permit the body electrolytes to fill these passages for conducting the electricity from the electrically conductive part of this electric terminal into the tissue.
The electrically conductive material or substrate of this electric terminal preferably is an inert porous or non-porous material and must be compatible to the body tissue and body fluids in which it is implanted. Such ;` ~ materials include~ for example: platinum~ iridium~ niobium, indium~titanium, tantalum7 vanadium~ tungsten~ chromium~ cobalt~ stainless steel~
an alloy of some of these metals called Vitallium or Elgiloy~ carbon, or the like. These materials may be formed into various shapes for intimate contact or implantation in or onto the particular tissue which is to be stimulated or sensed.
The porous layer or coating on the electrically conductive part of this electric terminal occurs at least upon the surface which is in contact with the tissue to be sensed or stimulated, and preferably all of its surface not to be electrically insulated from the tissue. This porous layer may comprise either a porous layer of the same or other electrically conductive material, or may comprise a coating of a non-electrically conductive porous r ~ -2-~383~
material. These porous materials may range from 5% to 85% porous in which a sufficient number of the pores interconnect and are continuous so that the layer is easily permeable to the electrolytes in the organic tissue.
The size of the pores may vary anywhere between about 0. 5 microns in diameter up to about lO00 microns, however, it has been found that pores whose average diameters fall within the range of about 10 and 500 microns are most satisfactory. The pore sizes must be sufficient for the blood vessels and tissue to grow into them for better intimate contact with the tissue to be electrically sensed or stimulated.
IF this porous layer is of an electrically conductive material, it may be of metal, carbon, a metal plated or coated non-conductive material, an electrically conductive plastic which may contain metal, and/or carbon, or it may be same material as the substrate oF the electric terminal. These ~ ;
electrically conductive materials also may be combined with a ceramic to Form a porous permeable layer of the implantable electric terminal of this invention.If this porous kayer is of an electrically non-conductive material, it may be of a ceramic or metallic oxide, such as aluminum oxide, silicon dioxide, -~
or either or both of these oxides together with calcium, magnesium, titanium and/or zirconium oxides, or a porous ceramic of such oxides callecl Cerosium.
This porous layer also may comprise a plastic material, such as a natural or synthetic polymer or elastomer, such as fclr example a silicone, a fluorocarbon, an epoxy resin, nylon, a rubber, polyurethane, polyethylene, polypropylene, polycarbonate, or mixtures thereof preferably that are :
compatible with and implantable into organic tissues and fluids. These plastics also may be combined with a ceramic to form the porous permeable layer of the ; implanted electric terminal of this invention.
If the only electrical contact with the electric terminal is at the end of the continuous pores in the electrical non-conductive coating layer, the current density is greater for that electric terminal than it would be if its core or electrical conductive part were also porous, and/or iF the porous coating layer were also electrically conductive, such as being made out of an electrically conductive porous material or out oF an electrically non-conductiveporous material coated or plated with an electrically conductive material, such as a non-reacting metal.
~133~7~
The implantable electric terminals of this invention are effective for use as sensors and/or stimulators For the heart, for the bladder, the pancreas, the central nervous system, the carotid sinus, the lungs, For bone healing, for pain control stimulators, and the like.
Accordingly, it is an object of this invention to produce an implant-able electric terminal for organic tissue which intermeshes with the tissue, and permits ingress of blood vessels without the production of a fibrous tissue interface that increases the stimulating threshhold level.
Another object is to control the current density of an implantable electric terminal by increasing or decreasing the conductive surface area of such a terminal.
A principal object of the invention is to provide a non-reactîng impantable electric terminal for an organic tissue comprising: an electrically conductive portion having a surface thereof adapted to contact tissue electro-lyte, said surface being completely surrounded and in intimate contact with an ~ "
inert, non-absorbable porous material having interconnected and continuous pores of an average diameter of between 10 and 500 microns so as to permit ingress of blood capillaries and intermeshing with said tissue without the forma- -tion of a fibrous tissue interface adjacent said surrounding part, and to permitelectrolytes in the tissue to pass therethrough and to be in continious contact with said electrically conductive portion, and means for connecting the electri-cally conductive portion of said electric terminal to an electrical circuit means.
The above mentioned and other features~ objects and advantages~
; and a manner of obtaining them are described more specifically below by reference to embodiments of this invention shown in the accompanying drawings9 wherein:
Figure I is an enlarged perspective view of one embodiment of an electric terminal according to this invention, comprising a disk implanted on the surface of the tissue to be sensed or stimulated;
Figure ll is a further enlarged section taken along line ll - ll of Figure I showing the separate electrically conductive and electrically non-conductive parts of this electric terminal;
Figure lll is an enlarged side view of a helical shaped electric terminal for insertion in a tissue, which terminal has a porous coating thereon;
~33~t'l6 Figure IV is a further enlarged section taken along line IV - IV of Figure lll showing the porous coating surrounding the central electrically con-ductive part of the electric terminal;
Figure V is a section similar to Figure IV of another embodiment oF
this invention, in which the central electrically conductive part is porous also;
Figure Vl is a section similar to Figure IV of a further embodiment -~
of this invention in which the electrically non-conductive porous layer is plated with an electrically conductive material; and Figure Vll is a section similar to Figure IV of still another embodi-10 ment of this invention, in which the outer porous portion is of the same electri-cally conductive material as the substrate.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Referring first to l=igures I and ll, there is shown a disk-shaped t electric terminal 10 implanted on organic tissue T, such as an epicardium.
This electric terminal 10 is shown to have an electrically conductive metallic substrate or disk portion 12 into which may be axially threaded or soldered a similar metal conductor rod or wire 14 connected to an electrical sensor or stimulator circuit means 15 to which another electrode 10 by means of a con-ductor 14 is also connected to another portion of tissue T in the same body.
20 On at least one of the flat surfaces 16 of the disk portion 12, and herein shown also around the periphery of the disk portion 12, is a layer of porous material 20. This porous material 20 is shown to be an electrically non-conductive ceramic material; such as aluminum oxide, containing a plurality of inter-connected and continuous pores 22. Thus pores 22 fill with body electrolytes for conducting electricity between the disk 12 and the tissue T. A~so into these pores 22 grow the blood capillaries C from the tissue T upon which the surface 24 of the disk 20 is intimately placed. This porous ceramic part 20 may be separately formed and then attached to the disk 12, or it may be sintered or integrally formed onto the disk 12.
Although this electric terminal 10 may be used either for electrically ; stimulating or sensing the tissue T, this electricity reaches the electrically conductive part 12 of this electric terminal 10 through the electrolyte in the pores 22 from the tissue T~ and thence is conducted through the conductor or wire 14 out to the instrument 15 that generates or senses this electricity.
,.
~3~76 Referrin~ now to the embodiment shown in Figures lll and IV~ the electrically conductive material or central wire portion 32 of the electric terminal 30 has an electrically non-conductive porous material coating or layer 40 thereon. This layer 40 may be separately formed and then a wire or post, such as the helical wire 32 threaded therein, or the porous layer 40 may be sintered or integrally formed onto the electrically conductive part 32. This porous layer 40 also has pores 42 that interconnect and are continuous so as to be permeable to body or tissue liquids from its outer surFace inwardly to the electrically conductive part 32.
In the above described embodiments, the current density of the electric terminal 10 or 30 is relatively high since the only electrically conduc-tive contact between the electrically conductive material 12 or 32 of the terminai is where the continuous pores 22 or ~2 through the outer electrically non-conductive part open onto the outer surface 16 of the disk 12 or onto the outer surFace of the center wire 32 for direct contact with the body electrolytes.
In order to decrease this current density or increase the surface area of the electric terminal of this invention for contact with the body electrolytes in the body tissue T, the center electrically conductive part may be made porous also as shown in Figure V, or the porous surrounding ;layer may be made of an electrically conductive material by being plated with a metal as shown in Figure Vl, or be made of an electrically conductive material different from or the same as or integrally with the center part as shown in Figure Vll.
Specifically, Figure V shows a cross-seGtion of an electric lerminal 50 having an electricaily non-conductive outer layer 60 with pores 62 and a center electrically conductive part 52 with pores 54 which fill with electrolyte from the tissue which passes through the pores 62.
Instead o-F or to3~i~ with the embodiment shown in Figure V, the outer porous layer 80 (see Figure Vl) of an implantable electric terminal 70 may be plated with a non reacting metal or electrically conductive material 84 which plating also coats the surfaces of the continuous pores 82 so as to be in electrical contact with the electrically conductive center part 72, thereby increasing the current density of the electric terminal over that described in Figures ll and lll.
Rather than plating the electrically non-conductive porous layer of : -6-~ 336~76 the electric terminal of this invention, this whole porous layer may be made of an electrically conductive material of a different or the same composition as the electrically conductive center part; including forming the whole electric terminal ;
out of the same material as shown in Figure Vll for the electric terminal 90 having an outer layer 100 with interconnected and continuous pores 102, and a center part 92, which center part may also be porous as shown in the embodi ment of F i gure V.
It is to be understood that other shapes of the implantation electric terminals oF this invention can be made embodying tissue compatible electrically ;
10 conductive material having a porous layer thereon, which layer may be either separate or of the same material as the electrically conductive substrate of the electric terminal. Thus the disk shaped electric terminal 10 as shown in the embodiment in Figures I and ll may have its porous disk part 20 formed of an electrically conductive material, such as shown in the embodiments of Figures V, Vl and/or Vll~ without departing from the scope of this invention.
Furthermore, the thickness of the porous layer may vary as desired, however, generally the dimensions of the electric terminal shown in Figures I
and ll have as their largest dimension about one centimeter, and as their smallest dimension~ i. e. their thickness preferably less than about one quarter 20 of a centimeter.
While there is described above the principles of this invention in connection with specific apparati, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of th i s i nven t i on .
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.. , .. . ,, ., ~ ..
Claims (26)
1. A non-reacting implantable electric terminal for an organic tissue comprising: an electrically conductive portion having a surface thereof adapted to contact tissue electrolyte, said surface being completely surrounded and in intimate contact with an inert, non-absorbable porous material having interconnected and continuous pores of an average diameter of between 10 and 500 microns so as to permit ingress of blood capillaries and intermeshing with said tissue without the formation of a fibrous tissue interface adjacent said surrounding part, and to permit electrolytes in the tissue to pass therethrough and to be in continuous contact with said electrically conductive portion, and means for connecting the electrically conductive portion of said electric terminal to an electrical circuit means.
2. An electric terminal according to claim 1 wherein said electri-cally conductive portion and said porous material are compatible with said electrolytes and said tissue.
3. An electric terminal according to claim 1 wherein said electri-cally conductive portion is an implantable metal.
4. An electric terminal according to claim 1 wherein said porous material comprises a ceramic metallic oxide.
5. An electric terminal according to claim 4 wherein said porous ceramic comprises aluminum oxide.
6. An electric terminal according to claim 1 wherein said porous material comprises a plastic.
7. An electric terminal according to claim 6 wherein said porous plastic is an elastomer.
8. An electric terminal according to claim 1 wherein said porous material comprises a mixture of a ceramic and plastic material.
9. An electric terminal according to claim 1 wherein said porous material is between about 5% and 85% porous.
10. An electric terminal according to claim 1 wherein said electri-cally conductive portion is substantially completely surrounded by said porous material.
11. An electric terminal according to claim 1 wherein said porous material is electrically conductive.
12. An electric terminal according to claim 1 wherein said electri-cally conductive portion and said porous material have substantially the same chemical composition.
13. An electric terminal according to claim 1 wherein said porous material forms a layer on said electrically conductive portion.
14. An electric terminal according to claim 1 wherein said electri-cally conductive portion is porous.
15. An electric terminal according to claim 1 wherein said porous material including its pores are coated with an electrically conductive material.
16. A non-reacting electric terminal for contact with organic tissue, comprising:
a) a tissue compatible electrically conductive material having `
a surface thereof adapted to contact tissue electrolyte, and b) a porous layer of a tissue compatible inert non-absorbable material completely surrounding and in intimate contact with said surface of said conductive material, wherein at least some pores are interconnected through the thickness of said layer and have an average diameter ranging between about 10 and 500 microns, whereby blood vessels of said organic tissue can penetrate said pores without the formation of a fibrous tissue interface between said tissue and said materials adjacent said layer, and whereby electrolytes in said tissue can contact said electrically conductive material; and c) means for connecting the electrically conductive material of said electric terminal to an electrical circuit means.
a) a tissue compatible electrically conductive material having `
a surface thereof adapted to contact tissue electrolyte, and b) a porous layer of a tissue compatible inert non-absorbable material completely surrounding and in intimate contact with said surface of said conductive material, wherein at least some pores are interconnected through the thickness of said layer and have an average diameter ranging between about 10 and 500 microns, whereby blood vessels of said organic tissue can penetrate said pores without the formation of a fibrous tissue interface between said tissue and said materials adjacent said layer, and whereby electrolytes in said tissue can contact said electrically conductive material; and c) means for connecting the electrically conductive material of said electric terminal to an electrical circuit means.
17. An electric terminal according to claim 16 wherein said electri-cally conductive material is an implantable metal.
18. An electric terminal according to claim 16 wherein said porous material comprises a ceramic metallic oxide.
19. An electric terminal according to claim 18 wherein said porous ceramic comprises aluminum oxide.
20. An electric terminal according to claim 16 wherein said porous material comprises a plastic.
21. An electric terminal according to claim 16 wherein said porous layer is between about 5% and 85% porous.
22. An electric terminal according to claim 16 wherein said electrically conductive material is substantially completely surrounded by said porous layer of tissue compatible material.
23. An electric terminal according to claim 16 wherein said porous layer of material is electrically conductive.
24. An electric terminal according to claim 16 wherein said electrically conductive material and said porous layer of tissue compatible material have substantially the same chemical composition.
25. An electric terminal according to claim 16 wherein said electrically conductive material is porous.
26. An electric terminal according to claim 16 wherein said porous layer including its pores are coated with an electrically conductive material.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA270,034A CA1083676A (en) | 1977-01-19 | 1977-01-19 | Implantable electric terminal for organic tissue |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA270,034A CA1083676A (en) | 1977-01-19 | 1977-01-19 | Implantable electric terminal for organic tissue |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1083676A true CA1083676A (en) | 1980-08-12 |
Family
ID=4107764
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA270,034A Expired CA1083676A (en) | 1977-01-19 | 1977-01-19 | Implantable electric terminal for organic tissue |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1083676A (en) |
-
1977
- 1977-01-19 CA CA270,034A patent/CA1083676A/en not_active Expired
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| MKEX | Expiry |