Porous PtIr Electrode Coating for High Capacitance
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Solution Overview
Problem
Existing medical electrodes face challenges in minimizing noble metal usage while maintaining high electrochemical capacitance and stability under anodic load, particularly due to the oxidation and dissolution of iridium-based coatings during neurological stimulation and the high cost and catalytic side effects of platinum.
Innovation Solution
A sputter process using simultaneous deposition from at least two targets, one iridium and one platinum, allows for the creation of a platinum-iridium alloy with adjustable stoichiometry, enabling a high iridium content and minimizing platinum usage, resulting in a porous coating with enhanced electrochemical capacitance and reduced catalytic activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If platinum is used as coating material to increase electrochemical capacitance, then capacitance is improved, but cost increases and catalytic side effects occur
Solution Approach 1:
The patent changes the compositional parameters of the coating by using platinum-iridium alloys with varying platinum content (1-50 at%). This parameter variation allows optimization where lower platinum content reduces catalytic side effects while maintaining sufficient electrochemical capacitance through the synergistic effect of iridium.
Solution Approach 2:
The patent employs composite platinum-iridium alloy materials instead of pure platinum. The composite structure combines the high capacitance properties of iridium with the catalytic activity of platinum in controlled ratios, achieving a balance between electrochemical performance and reduced harmful catalytic effects.
2Object-generated harmful factors
If iridium is used as coating material to reduce cost, then cost is reduced, but oxidation and dissolution occur during neurological stimulation
Solution Approach 1:
The patent introduces platinum as an intermediary element in the platinum-iridium alloy coating. Platinum acts as a mediator that suppresses the oxidation and dissolution of iridium under anodic conditions while maintaining the cost advantages of using iridium as the primary coating material.
Solution Approach 2:
The patent creates composite platinum-iridium alloys where the specific composition (1-50 at% Pt) provides mutual protection between the two metals. The alloy structure prevents iridium oxidation and dissolution while maintaining the lower cost benefit compared to pure platinum coatings.
3Reliability
If platinum-iridium alloy coating is applied to increase capacitance, then electrochemical capacitance is improved, but manufacturing complexity increases
Solution Approach 1:
The patent replaces complex multi-step coating processes with a single sputtering deposition step. By using sputtering technology, the platinum-iridium alloy coating can be applied in one process operation, simplifying manufacturing while achieving the desired alloy composition and electrochemical capacitance.
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 solution achieves a significant increase in electrochemical capacitance with minimal noble metal usage, maintaining stable impedance and preventing iridium oxidation, making it suitable for high-frequency neurological applications with reduced costs and side effects.
Implementation Method 1
A sputter process using simultaneous deposition from at least two targets, one iridium and one platinum, allows for the creation of a platinum-iridium alloy
Implementation Method 2
The surface area can thereby be increased, either by applying platinum-iridium spheroids and sintering them, or by coating a smooth surface with platinum black
Data Source
AI summary
An electrode for medical applications is provided with a PtIr coating which is at least partly porous. The coating contains more than 20% iridium by weight and at least 100 ppm Pt. The coated areas of the electrode exhibit an electrochemical capacitance of more than 5 mF/cm2 in physiological saline solution at 37° C. and a measurement frequency of 100 mHz. A sputter process is suitable for this purpose, in which a porous platinum-iridium layer is deposited on the electrode by simultaneously sputtering at least one iridium target and at least one platinum target.