Biocompatible Implantable Electrode Nanometer-Scale Voids
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Solution Overview
Problem
Current methods for increasing the surface area of implantable electrodes, such as coatings, face issues with adhesion and potential dislodgment, and existing surface modifications like laser etching cannot achieve the necessary nanometer-scale feature sizes for optimal electrical performance.
Innovation Solution
Applying ultrafast high energy pulses to a solid, monolithic electrode substrate using a femtosecond laser to create nanometer-scale voids on the surface, optimizing the surface topography for improved electrical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coating is applied to increase the surface area of the electrode, then the double layer capacitance increases and after-potential polarization decreases, but the coating may become dislodged during use creating irritation and reliability issues
Solution Approach 1:
The invention removes the coating layer entirely and instead modifies the substrate surface directly through laser texturing to create the desired nanometer-scale topography. This eliminates the adhesion problems and potential for coating dislodgment while maintaining the electrical performance benefits of increased surface area.
Solution Approach 2:
The laser texturing process creates localized nanometer-scale features (50-500 nm) on the substrate surface that provide the necessary surface area increase and electrical performance without requiring a separate coating material. The modification is confined to the surface layer while maintaining the bulk substrate integrity.
2Manufacturing precision
If conventional laser etching is used to modify the electrode surface, then surface features can be created, but the feature size cannot achieve the required nanometer scale (25,000 nm to 250,000 nm produced vs. 1 nm to 1000 nm required)
Solution Approach 1:
The invention changes the laser processing parameters, specifically using ultrafast laser pulses (femtosecond to picosecond duration) with controlled irradiance (200-5000 watts/cm²) to achieve nanometer-scale features. This represents a fundamental change from conventional continuous or long-pulse laser etching, enabling precise control of feature dimensions at the 50-500 nm scale.
Solution Approach 2:
The use of pulsed laser irradiation with specific pulse widths (1 femtosecond to 5 picoseconds) allows for periodic energy delivery that prevents excessive heat accumulation and enables precise nanometer-scale feature formation. The pulsed nature of the laser action facilitates controlled material removal or modification at the desired scale.
3Reliability
If the surface area of the electrode is increased to reduce after-potential polarization, then charge transfer efficiency improves, but the complexity of achieving and maintaining the surface structure increases
Solution Approach 1:
The laser texturing process is a self-contained modification that directly creates the functional surface structure on the substrate without requiring additional coating materials or complex multi-layer assemblies. The substrate itself serves as both the structural base and the functional surface, simplifying the overall device architecture while maintaining the desired electrical performance.
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 resulting electrode achieves reduced after-potential polarization, increased charge transfer efficiency, and enhanced sensing capabilities, leading to longer battery life and improved signal detection in medical devices.
Implementation Method 1
Applying ultrafast high energy pulses to a solid, monolithic electrode substrate using a femtosecond laser to create nanometer-scale voids on the surface
Implementation Method 2
exposing a solid, monolithic substrate to from about 10 to about 500 pulses of laser irradiation having a wavelength of from about 200 nm to about 1600 nm, at a pulse width of from about 1 femtosecond to about 5 picoseconds
Data Source
AI summary
A biocompatible, implantable electrode for electrically active medical devices. The implantable medical electrode has a surface geometry which optimizes the electrical performance of the electrode, while mitigating the undesirable effects associated with prior art porous surfaces. The electrode has an optimized surface topography for improved electrical performance. Such a electrode is suitable for devices which may be permanently implanted in the human body as stimulation electrodes, such as pacemakers, or as sensors of medical conditions. Such is achieved by the application of ultrafast high energy pulses to the surface of a solid, monolithic electrode material for the purpose of increasing the surface area and thereby decreasing its after-potential polarization.