Iridium Oxide Sputtered Electrodes for Cardiac Pacing

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Solution Overview

Problem

Current methods for creating enhanced microstructure surfaces on medical electrodes, such as those using platinum black particles and titanium nitride, are inefficient and do not adequately increase the active surface area, leading to persistent issues with post-pulse polarization in cardiac pacing and sensing applications.

Innovation Solution

The use of reactively sputtered iridium oxide (IrOx) films on electrode substrates, with specific process parameters like target power, sputtering pressure, and oxygen/argon ratios, to create a columnar microstructure that enhances the active surface area and reduces polarization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If traditional coatings of platinum black particles or titanium nitride are applied to electrode substrates, then the active surface area is increased, but the production efficiency remains low and post-pulse polarization persists

Engineering Contradiction:

Improveactive surface areaVSAvoidproduction efficiency

Core Design Contradiction:

Area of stationary objectVSProductivity

Solution Approach 1:

The patent replaces traditional mechanical coating methods with reactive sputtering, a physical vapor deposition technique that deposits iridium oxide films at the atomic level. This substitution enables precise control of surface microstructure and significantly improves production efficiency while maintaining enhanced active surface area.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent utilizes reactive sputtering with controlled parameters (oxygen/argon ratio, sputtering power, pressure) to transform the deposition process. By optimizing these parameters, the method creates columnar microstructure features that increase active surface area while improving manufacturing efficiency compared to traditional coating techniques.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If traditional coating methods are used to increase active surface area, then capacitance of the electrode-to-tissue interface is improved, but post-pulse polarization remains significant

Engineering Contradiction:

Improvecapacitance of electrode-to-tissue interfaceVSAvoidpost-pulse polarization

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The reactive sputtering process creates a columnar microstructure on the iridium oxide surface that provides porous-like features. This microstructure increases the effective surface area and capacitance at the electrode-to-tissue interface, thereby reducing post-pulse polarization effects while maintaining reliable electrical contact.

Inventive Principle:

Principle #31Porous materials

3Shape

If existing surface enhancement methods are used, then the electrode microstructure is improved, but new process-dependent surface microstructure features cannot be achieved

Engineering Contradiction:

Improveelectrode microstructureVSAvoidprocess-dependent surface microstructure features

Core Design Contradiction:

ShapeVSAdaptability or versatility

Solution Approach 1:

The patent replaces conventional mechanical or chemical coating methods with reactive sputtering, enabling the creation of process-dependent surface microstructure features. The physical vapor deposition process allows precise control over columnar microstructure formation, providing versatility in achieving different surface characteristics by adjusting deposition parameters.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The IrOx film surfaces demonstrate reduced post-pulse polarization voltages and comparable impedance to titanium nitride surfaces, improving the electrode-to-tissue interface capacitance and stability, while increasing production efficiency through higher deposition rates.

Implementation Method 1

Methodology Applied

Scientific EffectSputtering: Sputtering

Implementation Method 2

in order to increase a capacitance of the electrode-to-tissue interface, thereby reducing post-pulse polarization

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS8996129B2Medical electrode including an iridium oxide surface and methods of fabrication

Publication Date: 2015.03.31 MEDTRONIC INC

AI summary

An implantable medical electrode includes a substrate and an iridium oxide surface, which is formed by an iridium oxide film applied over a roughened surface of the substrate. The film is preferably applied via direct current magnetron sputtering in a sputtering atmosphere comprising argon and oxygen. A sputtering target power may be between approximately 80 watts and approximately 300 watts, and a total sputtering pressure may be between approximately 9 millitorr and approximately 20 millitorr. The iridium oxide film may have a thickness greater than or equal to approximately 15,000 angstroms and have a microstructure exhibiting a columnar growth pattern.