LCP Electrode Structure Nesting for Hermetic IMD Seals
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Solution Overview
Problem
Implantable medical devices (IMDs) with liquid crystal polymer (LCP) outer housings face challenges in maintaining a hermetic seal, which is essential for preventing moisture ingress and ensuring the integrity of the device's internal components, while also facilitating electrical connectivity for signal transfer and electrode attachment.
Innovation Solution
The use of electrical feedthroughs with non-uniform geometries and electrode structures attached to the LCP outer housing, which are designed to form a hermetic seal and reduce moisture ingress, while allowing for electrical connectivity between the internal circuitry and external electrodes or conductors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If electrical feedthroughs are used to extend through the LCP outer housing for electrical connectivity, then electrical connection between internal circuitry and external electrodes is enabled, but the hermetic seal may be compromised and moisture ingress risk increases
Solution Approach 1:
The electrode structure is nested within a depression formed in the LCP outer housing, with the LCP substrate of the electrode structure fitting into the depression and the electrical feedthrough extending through the housing to connect to the electrode. This nesting arrangement allows electrical connectivity while maintaining hermetic seal by integrating the electrode structure into the housing rather than attaching it to the exterior surface.
Solution Approach 2:
The LCP substrate acts as an intermediary between the LCP outer housing and the electrode, providing a transition region that maintains hermeticity. The depression in the housing and the LCP substrate together create a sealed interface that prevents moisture ingress while enabling electrical connection through the feedthrough to the electrode structure.
2Ease of manufacture
If electrode structures are attached to the outer surface of the LCP housing, then electrode attachment is facilitated, but the hermeticity of the housing may be compromised
Solution Approach 1:
The electrode structure with its LCP substrate is nested within a depression formed in the LCP outer housing. This nesting configuration allows the electrode to be attached in a recessed area, facilitating manufacturing while maintaining the hermetic seal by integrating the electrode structure into the housing rather than attaching it to the external surface where it could compromise hermeticity.
3Reliability
If a hermetic seal is maintained to prevent moisture ingress, then device reliability is improved, but electrical connectivity for signal transfer and electrode attachment becomes more difficult
Solution Approach 1:
The electrical feedthrough extends through the LCP outer housing to the depression where the electrode structure is nested, enabling electrical connectivity between internal circuitry and external electrodes while maintaining the hermetic seal. The nested configuration allows the feedthrough to pass through the housing material without compromising the seal integrity.
Solution Approach 2:
The LCP substrate serves as an intermediary component that bridges the hermetic housing and the electrode structure, allowing electrical connection to be established through the feedthrough while the LCP substrate and depression arrangement maintain the hermetic barrier against moisture ingress.
Data Source
AI summary
An IMD may include a liquid crystal polymer (LCP) outer housing defining an outer surface of the IMD, an electrical feedthrough extending through the LCP outer housing 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.