Capacitive Filter Feedthrough Assembly for EMI-Safe IMD Sealing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Implantable medical devices (IMDs) face challenges with electromagnetic interference (EMI) due to stray electromagnetic signals conducted by lead conductors, which can interfere with the normal operation of IMD circuitry, and existing feedthrough solutions do not adequately address this issue while maintaining a hermetic seal and ensuring reliable electrical connections.
Innovation Solution
The development of feedthrough assemblies that incorporate a capacitive filter array and a ferrule, using thick film conductive paste or lead frame assemblies to form electrical connections, which act as a low-pass filter to transmit high-frequency signals to ground and allow low-frequency signals to pass through, while maintaining a hermetic seal and physical separation to prevent EMI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hermetic seal is implemented in the feedthrough assembly, then reliability is improved, but device complexity increases due to the need for multiple components (ferrule, feedthrough, capacitive filter array)
Solution Approach 1:
The patent combines multiple functions into a single integrated feedthrough assembly structure. The ferrule, feedthrough, and capacitive filter array are merged into one hermetically sealed unit, where the feedthrough substrate integrates both the hermetic seal function and the electrical connection function, reducing the number of separate components while maintaining reliability
2Object-affected harmful factors
If a capacitive filter array is added to filter EMI, then harmful factors are reduced, but device complexity increases
Solution Approach 1:
The feedthrough substrate serves multiple functions simultaneously: it provides hermetic sealing, establishes electrical connections, and houses the capacitive filter array for EMI filtering. This multi-functionality approach integrates EMI protection into the existing feedthrough structure without adding separate filtering components
3Ease of manufacture
If thick film conductive paste is used to form electrical connections, then ease of manufacture is improved, but manufacturing precision requirements increase due to the need for proper firing and connection formation
Solution Approach 1:
The thick film conductive paste undergoes a phase transition during the firing process, changing from a soft paste state to a hardened ceramic-metal composite state. This phase transition allows the material to be easily applied in paste form while achieving precise, stable electrical connections after firing
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 proposed solution effectively filters out electromagnetic interference, ensuring reliable electrical connections and maintaining a hermetic seal, thereby preventing damage to IMD internal electronics and ensuring proper device operation.
Implementation Method 1
incorporate a capacitive filter array and a ferrule, using thick film conductive paste or lead frame assemblies to form electrical connections, which act as a low-pass filter to transmit high-frequency signals to ground and allow low-frequency signals to pass through
Implementation Method 2
heating the capacitive filter array, the ferrule, the feedthrough, and the thick film conductive paste to convert the thick film conductive paste from a paste to a relatively solid material
Data Source
Figure 1~3
Figure 4A~4B
Figure 5~6
AI summary
A feedthrough assembly may include a ferrule defining a ferrule opening, a feedthrough at least partially disposed within the ferrule opening, a capacitive filter array at least partially disposed within the ferrule opening, and a lead frame assembly. The feedthrough may include at least one feedthrough conductive pathway and the capacitive filter array may include at least one filter array conductive pathway. The lead frame assembly may include an electrically conductive lead electrically connecting the at least one feedthrough conductive pathway and the at least one filter array conductive pathway.