Implantable Control Module Coil for MRI Heating Reduction
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Solution Overview
Problem
Conventional implantable electrical stimulation systems are incompatible with magnetic resonance imaging (MRI) due to the generation of unwanted heating and induced currents caused by radiofrequency pulses, which can lead to tissue damage and premature failure of electronic components.
Innovation Solution
An implantable control module with a metallic housing and a coil that is shorted or coupled with a signal generator to oppose external electromagnetic fields, reducing eddy currents and heating by generating a magnetic flux that counters the external field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a metallic housing is used in the implantable control module, then structural strength and shielding are improved, but eddy currents and heating are generated during MRI exposure
Solution Approach 1:
A coil is introduced as an intermediary element between the external electromagnetic field and the metallic housing. The coil generates an opposing magnetic flux that acts as a mediator to cancel the external field's effect on the housing, preventing eddy currents while preserving the housing's structural integrity
Solution Approach 2:
The coil is configured to generate an opposing magnetic flux in advance of the harmful effect occurring in the metallic housing. By creating this counteracting magnetic field beforehand, the system prevents the generation of eddy currents and heating in the housing during MRI exposure
2Object-affected harmful factors
If the coil is shorted to generate opposing flux, then eddy currents in the metallic housing are reduced, but energy consumption increases
Solution Approach 1:
The shorting of the coil, which would normally be considered an energy-wasting condition, is converted into a beneficial protective mechanism. The shorted coil generates opposing flux that protects the metallic housing from eddy currents, transforming what would be pure energy loss into a useful shielding function
3Reliability
If the implantable control module is made MRI-compatible through flux opposition, then safety during MRI is improved, but device complexity increases
Solution Approach 1:
The coil serves multiple functions: it provides magnetic shielding during MRI procedures, maintains structural support within the device, and can potentially serve as part of the electromagnetic coupling system. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in 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
The solution effectively mitigates the adverse effects of MRI on implantable electrical stimulation systems by minimizing eddy currents and heating, ensuring safer and more reliable operation during MRI procedures.
Implementation Method 1
a coil disposed within or on the housing and configured and arranged to be shorted when an external electromagnetic field is applied in order to resist generation of an eddy current in the metallic structure of the exterior of the sealed housing in response to the external electromagnetic field
Implementation Method 2
resist generation of an eddy current in the metallic structure of the exterior of the sealed housing in response to the external electromagnetic field
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
An implantable control module for an implantable electrical stimulation system includes a housing with at least a portion of the exterior forming a metallic structure and at least a portion of the interior defining a sealed compartment. The control module further includes an electronic subassembly disposed in the sealed compartment; a connector assembly coupled to the housing and denning a port for receiving a lead; connector contacts disposed in the port to electrically couple with terminals of the lead; feedthrough interconnects extending from the connector assembly into the sealed compartment and coupling the connected contacts to the electronic subassembly; and a coil disposed within or on the housing and configured and arranged to be shorted when an external electromagnetic field is applied in order to resist generation of an eddy current in the metallic structure of the exterior of the sealed housing in response to the external electromagnetic field.