Implantable Probe Shield as Return Electrode for RF Safety
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Solution Overview
Problem
Implantable electro-stimulation devices face challenges with heating issues, undesired tissue stimulation during MR scanning, and inadequate shielding against external electromagnetic fields, which affect battery life and safety.
Innovation Solution
A probe with a conducting shield extending from the electrodes towards the proximal end, partially covered by an insulating material, serves as both a return electrode and a shield against external RF fields, ensuring focused stimulation and improved safety during MR scanning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a shield of conducting material covers a major part of the probe to protect against external electromagnetic fields, then shielding effectiveness is improved, but the probe structure becomes more complex and may interfere with electrode function
Solution Approach 1:
The shield is configured to serve dual functions: it acts as both a shield against external electromagnetic fields and as a return electrode for stimulation currents. This multi-functionality reduces the need for separate components, thereby simplifying the overall probe structure while maintaining effective shielding
Solution Approach 2:
The insulating material covers only part of the shield in the vicinity of the electrodes, leaving other portions exposed to function as return electrode. This localized differentiation allows different sections of the shield to have different functions, optimizing both shielding and electrical performance without requiring complete coverage
2Duration of action of moving object
If a return electrode is incorporated to reduce circuit impedance and increase battery life, then battery life time is improved, but the return electrode must be situated at a minimum distance from the stimulating electrode which may reduce stimulation effectiveness
Solution Approach 1:
The shield serves as both the return electrode and the shielding component, eliminating the need for a separate return electrode. This integration allows the return electrode function to be fulfilled by the shield structure itself, maintaining both battery life extension and stimulation effectiveness
Solution Approach 2:
The insulating material acts as an intermediary between the shield and the electrodes, positioned to prevent direct shunting of stimulation currents while allowing the shield to function as return electrode. This mediator enables the return electrode to be effectively positioned closer to the stimulating electrode without compromising stimulation effectiveness
3Object-affected harmful factors
If the shield extends close to the electrodes to provide optimum shielding, then shielding effectiveness is improved, but heating of the device and surrounding tissue during MR scanning may increase
Solution Approach 1:
The insulating material is positioned locally between the shield and the electrodes in the vicinity of the electrodes. This localized insulation creates a protective barrier that reduces heating at the electrode-shield interface during MR scanning, while allowing the shield to extend close to the electrodes for effective shielding against external electromagnetic fields
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 effectively reduces heating, minimizes unwanted tissue stimulation, and extends battery life by providing a large return electrode area and effective shielding against external electromagnetic fields, ensuring safe and efficient electro-stimulation.
Implementation Method 1
a shield of conducting material covering a major part of the probe, said shield extending from the vicinity of at least one of the one or more electrodes towards the proximal end or towards the distal end of the probe
Implementation Method 2
a layer of insulating material covering part of the shield in the vicinity of at least one of the one or more electrodes
Implementation Method 3
The part of the shield not covered by the insulating layer, viz. the exposed part of the shield, provides a return electrode for a stimulating current path
Data Source
AI summary
The invention relates to a probe for an implantable electro-stimulation device. The probe (20) has a distal end (12) and a proximal end (13), and moreover comprises: one or more electrodes (11) a shield (21) of conducting material covering a major part of the probe, said shield extending from the vicinity of at least one of the one or more electrodes (11) towards the proximal end (13) or towards the distal end (12) of the probe (20); and a layer (22a, 22b) of insulating material covering part of the shield (21) in the vicinity of the at least one of the one or more electrodes. The shield protects wires (14), extending from electrodes to the proximal end of the probe, from undesired interference of external RF fields. The exposed part of the shield not covered by the layer of insulating material serves as a return electrode for the electrostimulation signal path.