EP0596589A1
Expired / Lapsed
EP
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Method for reducing the polarization of bioelectrical stimulation leads using surface enhancement and product made thereby
Assignee: Telectronics NV
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Filing: 1993-06-01
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Granted: —
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Expires: 2013-06-01
Abstract
Abstract A method is disclosed for greatly reducing pacing polarization of a porous platinum bioelectrical stimulation electrode substrate (66) by applying an oscillating current to the electrode substrate while it is immersed in an electrolyte such as a sodium sulfate solution to electrochemically cause the formation of a thick, highly porous platinum hydrous oxide surface layer on the substrate. The surface layer is then slowly reduced to platinum, while maintaining an increased surface area structure therein, using a similar electrochemical process employing much lower levels of current. This method does not alter the electrode characteristics other than to increase the microsurface area. The reduced polarization follows from the known inverse relationship between microsurface area and polarization. An electrode (65) made by the foregoing method is also disclosed.
Inventors
- 👤 Josephus M. Otten
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 07:27
CPC Classifications
A; A61; A61N; A61N1/00; A61N1/02; A61N1/04; A61N1/05; A61N1/056; A61N1/0565
Claims Analysis
Total Claims: 34
Claim 1
Independent Claim
138 words
A method for manufacturing a metallic electrode of an implantable lead for generating bioelectrical stimulation pulses and sensing bioelectrical signals, comprising the steps of: immersing the electrode in an electrolyte solution; enhancing the surface of the immersed electrode by repetitively applying oscillating anodic and cathodic currents to the electrode at a predetermined frequency in the range of from 1 hertz to 10 kilohertz, said anodic and cathodic currents each having amplitudes in the range of from 1 milliampere to several amperes, so that a porous metallic hydrous oxide layer is formed on the surface of the immersed electrode; and reducing the hydroxide on the surface of the immersed electrode by applying a lower amplitude reducing current to the electrode, the reducing current having a predetermined amplitude in the range of from approximately 1 microampere to approximately 100 milliamperes.
Claim 2
Independent Claim
138 words
A method for manufacturing a metallic electrode of an implantable lead for generating bioelectrical stimulation pulses and sensing bioelectrical signals, comprising the steps of: immersing the electrode in an electrolyte solution; enhancing the surface of the immersed electrode by repetitively applying oscillating anodic and cathodic currents to the electrode at a predetermined frequency in the range of from 1 hertz to 10 kilohertz, said anodic and cathodic currents each having amplitudes in the range of from 1 milliampere to several amperes, so that a porous metallic hydrous oxide layer is formed on the surface of the immersed electrode; and reducing the hydroxide on the surface of the immersed electrode by applying a lower amplitude reducing current to the electrode, the reducing current having a predetermined amplitude in the range of from approximately 1 microampere to approximately 100 milliamperes.
Claim 3
Dependent Claim
44 words
A method in accordance with claim 1, wherein the oscillating current applied during said surface enhancing step is applied as a waveform selected from a group of waveforms including square wave varying currents, sinusoidally varying currents, triangular wave varying currents and staircase varying currents.
Claim 4
Dependent Claim
30 words
A method in accordance with claim 2, wherein the oscillating current applied during said surface enhancing step is periodically suspended by zero current intervals having a preset timing and duration.
Claim 5
Dependent Claim
48 words
A method in accordance with claim 1, wherein the oscillating current applied during said surface enhancing step is generated by controlling the voltage output waveform selected from a group of voltage waveforms including square wave varying voltages, sinusoidally varying voltages, triangular wave varying voltages and staircase varying voltages.
Claim 6
Dependent Claim
30 words
A method in accordance with claim 4, wherein the oscillating current applied during said surface enhancing step is periodically suspended by zero current intervals having a preset timing and duration.
Claim 7
Dependent Claim
35 words
A method in accordance with claim 1, wherein said anodic and cathodic currents each have individually predetermined amplitudes, and wherein the oscillating current applied during said surface enhancing step is asymmetric with respect to amplitude.
Claim 8
Dependent Claim
35 words
A method in accordance with claim 1, wherein said anodic and cathodic currents each have individually predetermined amplitudes, and wherein the oscillating current applied during said surface enhancing step is symmetric with respect to amplitude.
Claim 9
Dependent Claim
35 words
A method in accordance with claim 2, wherein said anodic and cathodic currents each have individually predetermined amplitudes, and wherein the oscillating current applied during said surface enhancing step is symmetric with respect to amplitude.
Claim 10
Dependent Claim
36 words
A method in accordance with claim 1, wherein said anodic and cathodic currents each have individually predetermined amplitudes, and wherein the oscillating current applied during said surface enhancing step is asymmetric with respect to duty cycle.
Claim 11
Dependent Claim
36 words
A method in accordance with claim 1, wherein said anodic and cathodic currents each have individually predetermined amplitudes, and wherein the oscillating current applied during said surface enhancing step is symmetric with respect to duty cycle.
Claim 12
Dependent Claim
24 words
A method in accordance with claim 8, wherein the oscillating current applied during said surface enhancing step is symmetric with respect to duty cycle.
Claim 13
Dependent Claim
24 words
A method in accordance with claim 1, wherein said surface enhancing step further comprises the step of applying physical motion to the electrolyte solution.
Claim 14
Dependent Claim
19 words
A method in accordance with claim 12, wherein said physical motion applying step is performed by activating a sonicator.
Claim 15
Dependent Claim
24 words
A method in accordance with claim 11, wherein said surface enhancing step further comprises the step of applying physical motion to the electrolyte solution.
Claim 16
Dependent Claim
19 words
A method in accordance with claim 14, wherein said physical motion applying step is performed by activating a sonicator.
Claim 17
Dependent Claim
27 words
A method in accordance with claim 1, wherein said surface enhancing step is performed for a predetermined duration in the range from 10 seconds to 72 hours.
Claim 18
Dependent Claim
27 words
A method in accordance with claim 15, wherein said surface enhancing step is performed for a predetermined duration in the range from 10 seconds to 72 hours.
Claim 19
Dependent Claim
58 words
A method in accordance with claim 1, wherein said hydroxide reduction current is a DC current and wherein said hydroxide reduction step further comprises the substeps of: repetitively measuring the voltage across the immersed electrode resulting from the applied hydroxide reduction current; and terminating said hydroxide reduction step when the measured voltage falls below a predetermined threshold voltage.
Claim 20
Dependent Claim
79 words
A method in accordance with claim 1, wherein said hydroxide reduction current is a DC current and wherein said hydroxide reduction step further comprises the substeps of: repetitively measuring the voltage across the immersed electrode resulting from the applied hydroxide reduction current; determining the rate of change of the measured voltage with respect to time; and terminating said hydroxide reduction step when the rate of change of the measured voltage with respect to time falls below a predetermined threshold.
Claim 21
Dependent Claim
58 words
A method in accordance with claim 17, wherein said hydroxide reduction current is a DC current and wherein said hydroxide reduction step further comprises the substeps of: repetitively measuring the voltage across the immersed electrode resulting from the applied hydroxide reduction current; and terminating said hydroxide reduction step when the measured voltage falls below a predetermined threshold voltage.
Claim 22
Dependent Claim
79 words
A method in accordance with claim 17, wherein said hydroxide reduction current is a DC current and wherein said hydroxide reduction step further comprises the substeps of: repetitively measuring the voltage across the immersed electrode resulting from the applied hydroxide reduction current; determining the rate of change of the measured voltage with respect to time; and terminating said hydroxide reduction step when the rate of change of the measured voltage with respect to time falls below a predetermined threshold.
Claim 23
Dependent Claim
84 words
A method in accordance with claim 20, wherein the electrolyte solution is approximately 0.5 Molar Na 2 S0 4 having a pH ranging from 5 to 6 and said surface enhancing step applies square wave anodic and cathodic currents to the electrode, said currents having an oscillating current frequency of approximately 350 Hz, said anodic current having an amplitude of approximately 90 mA and said cathodic current having an amplitude of approximately 90 mA, said surface enhancing step being applied for approximately 7.5 minutes.
Claim 24
Dependent Claim
84 words
A method in accordance with claim 11, wherein the electrolyte solution is approximately 0.5 Molar Na 2 S0 4 having a pH ranging from 5 to 6 and said surface enhancing step applies square wave anodic and cathodic currents to the electrode, said currents having an oscillating current frequency of approximately 1000 Hz, said anodic current having an amplitude of approximately 91 mA and said cathodic current having an amplitude of approximately 87 mA, said surface enhancing step being applied for approximately 7.5 minutes.
Claim 25
Independent Claim
215 words
A method for manufacturing a metallic electrode of an implantable lead for generating bioelectrical stimulation pulses and sensing bioelectrical signals, comprising the steps of: immersing the electrode in a first electrolyte solution; cleaning the surface of said immersed electrode by alternately applying anodic and cathodic square wave currents to the electrode at a predetermined frequency in the range of from 0.01 hertz to 1 hertz and for a duration ranging from 0.5 seconds to 1 hour, said anodic and cathodic currents each having amplitudes in the range of from 1 milliampere to 1 ampere; immersing the electrode in a second electrolyte solution; enhancing the surface of said electrode in said second solution by repetitively applying oscillating anodic and cathodic currents to the electrode at a predetermined frequency in the range of from 1 hertz to 10 kilohertz, said anodic and cathodic currents each having amplitudes in the range of from 1 milliampere to several amperes, so that a porous metallic hydrous oxide layer is formed on the surface of the immersed electrode; and reducing the hydroxide on the surface of said electrode in said second solution by applying a lower amplitude reducing current to the electrode, the reducing current having a predetermined amplitude in the range of from approximately 1 microampere to approximately 100 milliamperes.
Claim 26
Independent Claim
215 words
A method for manufacturing a metallic electrode of an implantable lead for generating bioelectrical stimulation pulses and sensing bioelectrical signals, comprising the steps of: immersing the electrode in a first electrolyte solution; cleaning the surface of said immersed electrode by alternately applying anodic and cathodic square wave currents to the electrode at a predetermined frequency in the range of from 0.01 hertz to 1 hertz and for a duration ranging from 0.5 seconds to 1 hour, said anodic and cathodic currents each having amplitudes in the range of from 1 milliampere to 1 ampere; immersing the electrode in a second electrolyte solution; enhancing the surface of said electrode in said second solution by repetitively applying oscillating anodic and cathodic currents to the electrode at a predetermined frequency in the range of from 1 hertz to 10 kilohertz, said anodic and cathodic currents each having amplitudes in the range of from 1 milliampere to several amperes, so that a porous metallic hydrous oxide layer is formed on the surface of the immersed electrode; and reducing the hydroxide on the surface of said electrode in said second solution by applying a lower amplitude reducing current to the electrode, the reducing current having a predetermined amplitude in the range of from approximately 1 microampere to approximately 100 milliamperes.
Claim 27
Dependent Claim
42 words
A method in accordance with claim 24, further comprising the step, following a last cycle of said surface cleaning step, of reducing the applied current from the current applied during the final surface cleaning step cycle to zero in a stairstep manner.
Claim 28
Dependent Claim
139 words
An electrode of an implantable lead for generating bioelectrical stimulation pulses and sensing bioelectrical signals, comprising: a noble metal conductive substrate; and a noble metal, porous, conductive low impedance surface layer overlying said conductive substrate, said surface layer having been formed by immersing the conductive substrate in an electrolyte solution, enhancing the surface of the immersed substrate by repetitively applying oscillating anodic and cathodic currents to the substrate at a predetermined frequency in the range of from 1 hertz to 10 kilohertz, said anodic and cathodic currents each having amplitudes in the range of from 1 milliampere to several amperes, and reducing the hydroxide on the surface of the immersed substrate by applying a lower amplitude reducing current to the substrate, said reducing current having an amplitude in the range of from approximately 1 microampere to approximately 100 milliamperes.
Claim 29
Dependent Claim
139 words
An electrode of an implantable lead for generating bioelectrical stimulation pulses and sensing bioelectrical signals, comprising: a noble metal conductive substrate; and a noble metal, porous, conductive low impedance surface layer overlying said conductive substrate, said surface layer having been formed by immersing the conductive substrate in an electrolyte solution, enhancing the surface of the immersed substrate by repetitively applying oscillating anodic and cathodic currents to the substrate at a predetermined frequency in the range of from 1 hertz to 10 kilohertz, said anodic and cathodic currents each having amplitudes in the range of from 1 milliampere to several amperes, and reducing the hydroxide on the surface of the immersed substrate by applying a lower amplitude reducing current to the substrate, said reducing current having an amplitude in the range of from approximately 1 microampere to approximately 100 milliamperes.
Claim 30
Dependent Claim
48 words
An electrode in accordance with claim 26, wherein said low impedance surface layer is enhanced by applying the oscillating anodic and cathodic currents as a waveform selected from a group of waveforms including square wave varying currents, sinusoidally varying currents, triangular wave varying currents and staircase varying currents.
Claim 31
Dependent Claim
43 words
An electrode in accordance with claim 27, wherein said anodic and cathodic currents each have individually predetermined amplitudes, and wherein said low impedance surface layer is enhanced by applying the oscillating anodic and cathodic currents as a symmetric waveform with respect to amplitude.
Claim 32
Dependent Claim
20 words
An electrode in accordance with claim 28, wherein the duty cycle of said oscillating anodic and cathodic currents is symmetrical.
Claim 33
Dependent Claim
33 words
An electrode in accordance with claim 29, wherein said low impedance surface layer is enhanced by applying physical motion to the electrolyte solution while said oscillating anodic and cathodic currents are being applied.
Claim 34
Dependent Claim
16 words
An electrode in accordance with claim 30, wherein said physical motion is generated by a sonicator.
References Cited (Backward Citations)
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