Thin-Film Electrode Assembly with Soft Silicone Overmold
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Solution Overview
Problem
Conventional neuromodulation devices face limitations in design complexity and mechanical properties, with bulk silicone substrates being unsuitable for conventional metallization techniques and polyimide-based materials causing tissue damage due to stiffness mismatch.
Innovation Solution
A thin-film electrode assembly with a soft overmold comprising silicone and a supporting structure of polyimide or liquid crystal polymer, allowing for greater design complexity and a soft interface that mitigates tissue damage, achieved through a manufacturing method involving multiple polymer layers and wire integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bulk silicone substrate is used, then mechanical properties and biocompatibility are improved, but design complexity and metallization capability deteriorate
Solution Approach 1:
The device is segmented into distinct functional layers: a thin-film polyimide substrate for complex metallization and electrode patterning, and a bulk silicone overmold for mechanical compliance and biocompatibility. This segmentation allows each material to optimize its strengths while the assembly achieves both design complexity and biocompatibility.
Solution Approach 2:
The invention uses a composite structure combining thin-film polyimide and bulk silicone materials. The thin-film polyimide layer enables conventional metallization techniques and complex electrode designs, while the bulk silicone overmold provides tissue-compatible mechanical properties, creating a composite device that achieves both design complexity and biocompatibility simultaneously.
2Device complexity
If polyimide-based material is used, then design complexity is improved, but mechanical properties and tissue compatibility deteriorate
Solution Approach 1:
Different regions of the device have different material properties optimized for their specific functions: the thin-film polyimide region provides design complexity and metallization capability where needed, while the bulk silicone overmold provides soft, compliant tissue interface properties at the region contacting the body, eliminating tissue damage while preserving design complexity.
Solution Approach 2:
The composite structure combines thin-film polyimide for complex electrode patterns with bulk silicone for tissue-compatible mechanics. The silicone overmold acts as a protective interface layer that prevents the stiffer polyimide from causing tissue damage, while allowing the polyimide to provide its full design complexity potential.
3Ease of manufacture
If thin-film substrate is used, then metallization capability is improved, but mechanical compliance and tissue compatibility deteriorate
Solution Approach 1:
The bulk silicone overmold acts as an intermediary layer between the thin-film polyimide substrate and the biological tissue. It mediates the mechanical interaction by providing a soft, compliant interface that protects tissue from the stiffer thin-film substrate, while allowing the thin-film to maintain its metallization capability for manufacturing.
Data Source
AI summary
The present disclosure relates to implantable neuromodulation devices and methods of fabrication, and in particular to a thin-film electrode assemblies and methods of fabricating the thin-film electrode assembly to include a soft overmold. Particularly, aspects of the present invention are directed to a thin-film electrode assembly that includes an overmold and a supporting structure formed within a portion of the overmold. The overmold includes a first polymer and the supporting structure includes a second polymer, different from the first polymer. The thin-film electrode assembly also includes a wire formed within a portion of the supporting structure, and an electrode formed on a top surface of the supporting structure and in electrical contact with the wire.