Implantable Feedthrough EMI Filtering via PCB Ground Layers
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Solution Overview
Problem
Current hermetic seal feedthrough assemblies for implantable medical devices are costly due to the integration of complex multilayer laminated capacitors for electromagnetic interference filtering, which increases the expense of these devices.
Innovation Solution
A filtered feedthrough assembly incorporating a printed circuit board with multiple ground layers and vias, along with capacitors and conductive epoxy, provides a parallel-path ground return mechanism that reduces inductive effects and enhances signal attenuation, thereby improving the band filtering performance of the electromagnetic filter system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex multilayer laminated capacitors are integrated into the feedthrough assembly for electromagnetic interference filtering, then the filtering performance is improved, but the device cost increases significantly
Solution Approach 1:
The patent divides the ground return path into multiple separate ground layers within the PCB, each providing an independent filtering path. This segmentation allows the system to achieve superior EMI filtering performance through the combined effect of multiple parallel paths, effectively replacing the need for a single complex multilayer capacitor while maintaining or improving filtering capability.
Solution Approach 2:
The invention transitions from a single-point filtering approach (using one capacitor) to a distributed multi-dimensional filtering approach by implementing multiple ground layers stacked in three-dimensional space within the PCB. This dimensional expansion creates multiple parallel filtering paths that collectively provide enhanced EMI rejection without requiring expensive complex capacitors.
2Reliability
If complex multilayer laminated capacitors are used for filtering external signals, then the voltage level stability is improved, but the manufacturing cost increases
Solution Approach 1:
The patent creates multiple copies of the ground return path by implementing replicated ground layers within the PCB structure. Each ground layer serves as a parallel copy of the filtering function, providing redundant voltage stabilization paths. This copying approach achieves superior voltage level stability through the cumulative effect of multiple paths, replacing the need for expensive complex capacitors with standard PCB manufacturing techniques.
3Reliability
If multiple ground layers with vias are implemented to reduce inductive effects, then the signal attenuation is improved, but the PCB complexity increases
Solution Approach 1:
The patent implements multiple ground layers connected through vias to create equipotential surfaces throughout the PCB structure. This equipotential design minimizes inductive effects by ensuring that all ground points remain at the same electrical potential, thereby reducing ground loops and inductance. The multiple ground layers work together to provide uniform potential distribution, improving signal attenuation without requiring complex external components.
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 decreases the cost of implantable medical devices by providing effective electromagnetic interference filtering while maintaining the intended voltage levels, thus improving the overall performance and reducing the complexity of the feedthrough assemblies.
Implementation Method 1
The electromagnetic filters typically include complex multilayer laminated capacitors that are configured to filter external signals of hundreds of volts
Implementation Method 2
The connection element being electrically coupled to the ground layer through the vias
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A filtered feedthrough assembly for an implantable medical device comprises a ferrule, an electrical insulator coupled to the ferrule by a connection element, a plurality of feedthrough conductors extending through the electrical insulator, a printed circuit board (PCB), and plurality of capacitors. The PCB is coupled to the ferrule or the electrical insulator, and includes one or more ground layers and a plurality of vias. The connection element is electrically coupled to the ground layer through the vias. The capacitor has a ground terminal electrically coupled to the ground layer through at least one of the vias, and a conductor terminal electrically coupled to the feedthrough conductor.