Segmented Electrode Overmolding for Medical Leads
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Solution Overview
Problem
Manufacturing discrete electrode segments on small diameter leads for medical devices is challenging, particularly when multiple segments are required, due to difficulties in overmolding and achieving precise placement and isolation of conductors.
Innovation Solution
The development of a medical lead with segmented electrodes, where each electrode is divided into multiple segments, each with its own conductor, and overmolded with specific portions to allow for precise positioning and isolation, using tabs and keys to ensure accurate assembly and minimize conductor interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If discrete electrode segments are manufactured on small diameter leads, then directional stimulation precision is improved, but manufacturing difficulty increases
Solution Approach 1:
The electrode is divided into multiple discrete segments (e.g., first electrode segment, second electrode segment, third electrode segment) around the lead circumference, allowing independent activation for directional stimulation. Each segment is electrically isolated and can be controlled separately to target specific brain regions.
Solution Approach 2:
Multiple electrode segments are arranged concentrically around the small diameter lead, with each segment nested in the circular cross-section. This allows multiple discrete electrodes to fit on a small lead while maintaining their individual functionality and electrical isolation.
2Quantity of substance
If multiple electrode segments are placed on a small diameter lead, then electrode segment density is improved, but overmolding difficulty increases
Solution Approach 1:
The electrode structure is segmented into multiple discrete sections around the lead, with each segment having its own conductor and insulation. This segmentation allows for precise positioning and isolation during the overmolding process, making it feasible to manufacture high-density electrode arrays on small leads.
Solution Approach 2:
Different portions of the lead surface are assigned different functions - some areas have electrode segments while others have insulation or structural support. This local differentiation allows the overmolded structure to accommodate high electrode density in specific regions while maintaining manufacturability through varied material properties in different zones.
3Reliability
If conductor isolation is achieved for multiple electrode segments, then electrical connection quality is improved, but assembly complexity increases
Solution Approach 1:
An overmolded insulating material serves as an intermediary between adjacent electrode segments and conductors, providing electrical isolation and mechanical support. This intermediary structure simplifies assembly by automatically isolating conductors during the molding process rather than requiring separate isolation steps for each conductor pair.
Solution Approach 2:
The functions of conductor insulation, electrode segment isolation, and structural support are merged into a single overmolded component. This integration reduces assembly complexity by combining multiple isolation and support functions into one manufacturing step, while still ensuring high-quality electrical connections between each conductor and its corresponding electrode segment.
Data Source
AI summary
One aspect is forming a medical lead for implantation. The method includes forming a plurality of non-ground electrodes, at least one non-ground electrode having a plurality of segments. Overmold portions are formed for the at least one of the plurality of non-ground electrodes, including keys and tabs. One of a plurality of conductors is attached to one segment of the at least one non-ground electrode using the keys and tabs. The non-ground electrodes and plurality of conductors are assembled into electrode assembly and the overmold portions are reflowed. The reflowed electrode assembly is then ground to form the medical lead.