RF Choke Inductor for MRI-Safe Implantable Lead
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Implantable medical devices, such as neurostimulators, face issues with undesirable heating during MRI scans due to induced RF currents in the leads, which can cause temperature increases and potential device damage.
Innovation Solution
An implantable lead is designed with a conductive filer and a coil of wire wound on a bobbin to form an inductor between the stimulation portion and the distal end, acting as an RF choke to reduce energy induced in the lead electrodes during an MRI scan, thereby minimizing heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a standard implantable lead is used during MRI scanning, then the lead can deliver electrical stimulation therapy, but RF currents are induced in the lead causing undesirable heating at the electrode
Solution Approach 1:
An RF choke (inductor) is introduced as an intermediary component between the lead electrode and the neural tissue. This inductor acts as a mediator that blocks RF currents from reaching the electrode while allowing the electrode to maintain its stimulation function, thus preventing heat generation without compromising therapy delivery
Solution Approach 2:
The impedance characteristics of the lead are changed by adding an inductor with specific inductance value (at least 0.5 microhenry). This parameter change creates frequency-dependent impedance that blocks high-frequency RF currents while maintaining low-frequency stimulation current flow, thereby preventing electrode heating during MRI
2Temperature
If an RF choke is added to the lead to reduce induced energy, then heat generation at the electrode is minimized, but the device complexity increases
Solution Approach 1:
The inductor is nested within the existing lead structure, with the inductor wire wound around a bobbin that is positioned within the lead body. This nesting approach integrates the RF choke functionality into the existing lead architecture without requiring separate external components, thereby minimizing the increase in device complexity
3Reliability
If the inductor has high inductance to effectively block RF currents, then less induced energy reaches the electrode, but the inductor occupies more space within the lead
Solution Approach 1:
The inductor is constructed using a thin-walled bobbin structure that allows the inductor wire to be wound in a compact configuration. This thin-film approach enables the inductor to achieve the required inductance (at least 0.5 microhenry) while occupying minimal space within the lead, effectively blocking RF induced energy without significantly increasing lead volume
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 RF choke effectively reduces heat at the stimulation electrodes, ensuring the implantable medical device can be safely operated in an MRI environment without significant undesirable heating.
Implementation Method 1
at least one coil of wire wound on the bobbin and electrically coupled between the stimulation portion and the distal end region to form an inductor between the distal end region and the stimulation portion
Implementation Method 2
acting as an RF choke to reduce energy induced in the lead electrodes during an MRI scan
Implementation Method 3
to form an inductor between the distal end region and the stimulation portion
Data Source
AI summary
A lead configured to be implanted into a patient's body comprises a lead body and a conductive filer positioned within the lead body and having a distal portion. An electrode is electrically coupled to the lead body and comprises a stimulation portion, a bobbin, and at least one coil of wire wound on the bobbin and electrically coupled between the stimulation portion and the distal end region to form an inductor between the distal end region and the stimulation portion.