MRI-Safe Lead Electrode Using Fractal Surface Area
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Solution Overview
Problem
Implantable neurostimulation systems face issues with undesirable heating of electrodes due to induced RF currents during MRI scans, posing safety concerns and potential damage to the devices.
Innovation Solution
The development of an MRI-safe medical electrode assembly with a stimulation electrode configuration that includes a first section contacting the patient's body and a second section capacitively coupled to the body, effectively increasing the surface area to dissipate induced energy safely, thereby reducing heat generation at the electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional stimulation electrode is used in an MRI environment, then the electrode can deliver electrical stimulation to the patient's body, but the electrode experiences undesirable heating due to induced RF currents
Solution Approach 1:
The electrode transitions from a traditional solid conductor to a fractal structure that increases its effective surface area by utilizing self-similar patterns across multiple scales. This dimensional complexity allows the electrode to maintain electrical conductivity while dramatically increasing the surface area available for heat dissipation and reducing current density during MRI scans
Solution Approach 2:
The electrode employs a composite structure combining conductive materials with fractal geometries, integrating the electrical conductivity requirements with the thermal management requirements. The fractal pattern itself acts as a composite structure that balances electrical function with thermal dissipation capabilities
2Temperature
If the electrode surface area is increased to dissipate induced energy, then heat generation is reduced, but the device complexity increases
Solution Approach 1:
The electrode surface is segmented into self-similar fractal patterns that repeat at different scales. This segmentation creates multiple pathways for current distribution and heat dissipation, effectively increasing the functional surface area without requiring a proportionally larger overall electrode structure
Solution Approach 2:
The fractal electrode structure follows a nested pattern where smaller fractal elements are contained within larger fractal elements, creating a self-similar hierarchy. This nesting allows the electrode to pack increased surface area into a compact form factor, reducing the trade-off between surface area and device complexity
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 configuration reduces the current density and temperature increase at the electrodes, ensuring safe operation of implantable medical devices within an MRI environment by effectively shunting induced energy, thus minimizing heat generation and device damage.
Implementation Method 1
a second section capacitively coupled to the first section and configured to be electrically coupled to the patient's body
Data Source
AI summary
A medical lead is configured to be implanted into a patient's body and comprises a lead body, and an electrode coupled to the lead body. The electrode comprises a first section configured to contact the patient's body, and a second section capacitively coupled to the first section and configured to be electrically coupled to the patient's body.