LCP Feedthrough Electrode Nesting for Hermetic IMD Seals
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Solution Overview
Problem
Implantable medical devices (IMDs) with biocompatible outer housings face challenges in maintaining a hermetic seal, particularly with electrical feedthroughs, which can lead to moisture ingress and compromise the device's integrity.
Innovation Solution
The use of liquid crystal polymer (LCP) outer housings with specifically designed electrical feedthroughs and electrode structures that feature non-uniform widths and configurations, facilitating a hermetic seal and preventing moisture ingress, while allowing for efficient electrical connectivity and attachment to the housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical feedthroughs are used to provide electrical connectivity through the LCP housing, then electrical connection between internal circuitry and external electrodes is improved, but the hermetic seal is compromised leading to moisture ingress
Solution Approach 1:
The feedthrough electrode is nested within a recess formed in the LCP housing, creating a layered structure where the electrode is embedded in the housing material. This nesting approach allows the electrode to pass through the housing while the surrounding LCP material maintains the hermetic seal, preventing moisture ingress while preserving electrical connectivity.
Solution Approach 2:
The LCP housing acts as a flexible yet hermetic barrier that accommodates the feedthrough electrode. The LCP material's properties allow it to form a tight seal around the embedded electrode, maintaining protection against moisture while enabling electrical signal transmission through the housing structure.
2Object-affected harmful factors
If feedthrough electrodes are embedded in the LCP housing, then hermeticity is improved by preventing moisture ingress, but manufacturing precision is challenged due to alignment requirements
Solution Approach 1:
The recess for the feedthrough electrode is pre-formed in the LCP housing during the housing manufacturing process, before the electrode is actually installed. This preliminary preparation of the embedding location ensures proper alignment and positioning, reducing the precision requirements for subsequent electrode installation while maintaining hermetic sealing.
3Object-affected harmful factors
If recesses are formed in the LCP housing to accommodate feedthrough electrodes, then hermetic seal is improved, but device complexity increases due to additional structural features
Solution Approach 1:
The formation of the recess is merged with the LCP housing manufacturing process itself, rather than being a separate post-processing step. This integration allows the recess to be created as part of the molded housing structure, minimizing additional complexity while achieving the hermetic sealing benefit of embedded electrodes.
Data Source
Figure 1
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Figure 3E~3J
AI summary
An implantable medical device (IMD) may include a liquid crystal polymer (LCP) outer housing defining an outer surface of the IMD, circuitry disposed within the LCP outer housing, an electrical feedthrough extending through the LCP outer housing from a first end proximate the circuitry to a second end proximate to the outer surface, and an electrode structure disposed on the outer surface. The electrode structure may include a LCP substrate defining a first major surface and a second major surface substantially opposite the first major surface, a contact pad disposed on the first major surface, and an electrode disposed on the second major surface. The LCP substrate may be attached to the LCP outer housing and the contact pad may be electrically coupled to the electrical feedthrough.