Micro-Textured Catheter Electrodes for Lower Impedance Mapping
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Solution Overview
Problem
Small measurement electrodes in electrophysiology catheters experience increased impedance, which can lead to undesirable effects during procedures like electroanatomical mapping due to higher current density and limited ionic AC current, primarily because of their dimensional dependence and surface area limitations.
Innovation Solution
The surface of metallic electrodes in catheters is treated using laser texturing and/or applying coatings like titanium nitride, iridium oxide, or electro-conductive polymers to increase the microscopic surface area and reduce impedance, specifically using femtosecond lasers and deposition methods like chemical vapor deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If electrode dimensions are decreased to improve catheter flexibility and access, then the catheter can navigate vasculature more effectively, but impedance increases due to higher current density and limited ionic AC current
Solution Approach 1:
The patent transitions from considering only the macroscopic two-dimensional surface area of electrodes to incorporating the third dimension by creating microscopic surface structures through laser texturing. This increases the effective surface area without increasing the macroscopic footprint, thereby reducing impedance while maintaining small electrode dimensions for catheter flexibility.
Solution Approach 2:
The laser-textured electrode surfaces create a porous or micro-structured topology that increases the effective surface area available for ionic current exchange. This porous structure allows more charge accumulation sites while maintaining the same macroscopic electrode size, directly addressing the impedance issue in small electrodes.
2Reliability
If electrode surface area is increased to reduce impedance, then signal quality improves, but the macroscopic size of the electrode increases which may affect catheter flexibility
Solution Approach 1:
The invention resolves this contradiction by increasing surface area in the microscopic dimension rather than the macroscopic dimension. The laser-textured surfaces create complex micro-structures that provide large effective surface areas for signal detection while the overall macroscopic electrode footprint remains small, preserving catheter flexibility.
Solution Approach 2:
The micro-structures are nested within the macroscopic electrode geometry. The textured surface patterns are embedded in the electrode material itself, creating a hierarchical structure where microscopic features are contained within the larger electrode form, allowing increased surface area without increasing external dimensions.
3Reliability
If coating materials are applied to electrode surfaces to increase surface area, then impedance is reduced, but the manufacturing process becomes more complex
Solution Approach 1:
The laser texturing is performed as a preliminary step before coating application. By pre-texturing the substrate surface, the subsequent coating process benefits from the increased surface area already present, and the coating adheres to the textured pattern. This sequence simplifies manufacturing compared to attempting to create textures after coating.
Solution Approach 2:
The final electrode structure comprises a composite of the metallic substrate and the deposited coating material. The laser-textured substrate provides the micro-structure for increased surface area, while the coating layer (such as platinum or iridium oxide) provides electrochemical functionality. This composite approach allows each material to contribute its optimal properties.
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
This approach reduces the real component of impedance by up to 40% at frequencies below 20 kHz, enhancing the performance of electrophysiology catheters by improving signal clarity and localization during cardiac procedures.
Implementation Method 1
The surface of the metallic substrate is treated by applying laser energy to the surface of the metallic substrate, for example using a femtosecond laser, thereby texturing the surface of the metallic substrate.
Implementation Method 2
The coating may be applied by chemical vapor deposition, physical vapor deposition, or electrochemical deposition.
Implementation Method 3
The coating may be applied by chemical vapor deposition, physical vapor deposition, or electrochemical deposition.
Implementation Method 4
The coating may be applied by chemical vapor deposition, physical vapor deposition, or electrochemical deposition.
Data Source
AI summary
A medical device includes a body and at least one electrode disposed thereon. The electrode includes a metallic substrate, such as a platinum group metal, an alloy of platinum group metals, or gold. The surface of the substrate is modified in a manner that increases its effective surface area without inducing bulk heating. For example, the surface of the substrate can be laser textured and/or coated, such as with titanium nitride or iridium oxide.