Multipolar Feedthrough Filter Capacitor for AIMD EMI
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Solution Overview
Problem
Existing active implantable medical devices (AIMDs) face challenges with high manufacturing and assembly costs due to the use of dielectric materials with mismatched thermal coefficients and biocompatibility issues, particularly with barium titanate, which is effective but not strong enough for hermetic seals, and alumina ceramic, which is strong but has a low dielectric constant.
Innovation Solution
A multipolar feedthrough filter capacitor assembly using alumina ceramic with a dielectric constant below 10, combined with a secondary capacitor made of barium titanate with a dielectric constant above 1000, embedded within a ferrule and directly attached to a circuit board, providing a biocompatible and efficient filtering solution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If barium titanate is used for feedthrough filter capacitor, then capacitance efficiency is improved (dielectric constant above 1000), but mechanical strength and biocompatibility deteriorate (not strong enough for hermetic seals)
Solution Approach 1:
The device is divided into two functional segments: a barium titanate capacitor portion for high capacitance efficiency and an alumina ceramic hermetic seal portion for mechanical strength and biocompatibility. This segmentation allows each material to be optimized for its specific function without compromise.
Solution Approach 2:
The invention uses a composite structure combining barium titanate and alumina ceramic materials. The barium titanate provides the capacitive function while the alumina ceramic provides the hermetic seal function, creating a composite system that achieves both high capacitance efficiency and mechanical strength.
2Strength
If alumina ceramic is used for hermetic seal, then mechanical strength is improved, but capacitance efficiency deteriorates (low dielectric constant below 10)
Solution Approach 1:
The device is divided into two functional segments: a barium titanate capacitor portion for high capacitance efficiency and an alumina ceramic hermetic seal portion for mechanical strength and biocompatibility. This segmentation allows each material to be optimized for its specific function without compromise.
Solution Approach 2:
The invention uses a composite structure combining barium titanate and alumina ceramic materials. The barium titanate provides the capacitive function while the alumina ceramic provides the hermetic seal function, creating a composite system that achieves both high capacitance efficiency and mechanical strength.
3Ease of operation
If lead wires are used to connect to AIMD, then electrical connection is improved, but electromagnetic interference increases (leads act as antenna and pick up stray EMI signals)
Solution Approach 1:
The invention extracts and removes the problematic lead wire antenna effect by implementing a feedthrough capacitor structure that directly couples the capacitor to the hermetic seal, eliminating the need for separate lead wires that would act as antennas and pick up EMI signals.
Solution Approach 2:
The feedthrough capacitor acts as an intermediary element between the external circuit and the AIMD interior, providing electrical connection while simultaneously filtering EMI signals through its capacitive coupling, thus mediating between the need for connection and the need for EMI protection.
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 manufacturing costs, enhances biocompatibility, and achieves effective electromagnetic interference filtering while maintaining mechanical strength, addressing the limitations of previous materials by utilizing alumina ceramic for structural integrity and barium titanate for capacitance efficiency.
Implementation Method 1
a feedthrough filter capacitor which diverts high frequency electrical signals from a lead conductor(s) to the housing or case of an AIMD
Implementation Method 2
The plates are disposed within a dielectric substrate
Data Source
AI summary
A multipolar feedthrough filter capacitor assembly for an active implantable medical device includes a feedthrough filter capacitor including a first active electrode plate, a second active electrode plate and a plurality of ground electrode plates. The plates are in spaced parallel relation disposed within a monolithic dielectric substrate where the first and second active electrode plates are disposed between the plurality of ground electrode plates. A first conductive terminal pin is disposed through the feedthrough filter capacitor electrically coupled to the first active electrode plate and in non-conductive relation to both the second active electrode plate and ground electrode plate. A second conductive terminal pin may be disposed through the feedthrough filter capacitor electrically coupled to the second active electrode plate and in non-conductive relation to both the first active electrode plate and ground electrode plate.