Over-molded LCP Nerve Cuff Electrodes for Delamination Prevention
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Solution Overview
Problem
The manufacturing of nerve cuff electrodes is labor-intensive and costly due to the use of conventional materials like silicone and polyurethane, and the transition from planar liquid crystal polymer (LCP) substrates to cylindrical neurostimulation devices is mechanically and electrically challenging, with issues of delamination and rigidity.
Innovation Solution
The development of electrode leads and flexible circuits using planar dielectric substrates like LCP, with pre-shaped structures, slits to form planar strands, and insulative layers to address flexibility and delamination issues, and the use of cylindrical connectors to facilitate integration with neurostimulation devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional materials like silicone or polyurethane are used for nerve cuff electrodes, then the electrodes can be manufactured using traditional overmolding processes, but the manufacturing process becomes time-consuming and labor-intensive
Solution Approach 1:
The patent transitions from conventional silicone/polyurethane materials to liquid crystal polymer (LCP) substrates, changing the material parameters to enable new manufacturing capabilities. LCP substrates can be precision-molded and are amenable to photolithography and thin-film deposition, allowing circuitry to be fabricated directly on the substrate in a single integrated process rather than through separate overmolding steps, thereby dramatically increasing productivity while maintaining ease of manufacture
Solution Approach 2:
The patent employs LCP as a composite substrate material that combines mechanical flexibility with electrical insulation properties and biocompatibility. This composite approach integrates multiple functions (structural support, electrical insulation, and circuit fabrication substrate) into a single material system, eliminating the need for separate overmolding of insulative material and reducing manufacturing steps
2Productivity
If LCP substrates are used for nerve cuff electrodes, then manufacturing time and labor are reduced, but the substrates may be rigid in the plane along their surface
Solution Approach 1:
The patent divides the LCP substrate into multiple segments or layers, allowing each layer to be optimized for specific properties. The substrate may be constructed with multiple thin layers that can flex independently, or segmented into regions with different mechanical properties, enabling the overall structure to achieve flexibility in the plane while maintaining manufacturing efficiency
Solution Approach 2:
The patent employs thin-film deposition techniques to create flexible circuitry on the LCP substrate. The thin-film nature of the deposited materials (conductive traces, insulative coatings) allows the substrate to flex in the plane without compromising the integrity of the circuitry, reconciling the rigidity advantage of LCP with the flexibility requirement for neural implantation
3Manufacturing precision
If LCP substrates are used with planar geometry, then precision molding and photolithography can be applied, but the edges tend to be sharp causing potential tissue damage
Solution Approach 1:
The patent applies local quality by treating different regions of the LCP substrate differently. The bulk of the substrate maintains the precision-molded planar geometry for manufacturing advantages, while the edges are locally modified through techniques such as chamfering, rounding, or coating with softer materials to eliminate sharp edges and prevent tissue damage, thus achieving both manufacturing precision and biocompatibility
4Reliability
If LCP substrates are used for nerve cuff electrodes, then the substrate is inert and mechanically flexible, but the connector transition from planar to cylindrical form is mechanically challenging
Solution Approach 1:
The patent incorporates curvature and three-dimensional shaping of the LCP substrate to enable cylindrical connector transitions. The substrate may be formed with curved surfaces or pre-stressed geometries that allow it to wrap around or transition to cylindrical connector forms, eliminating the mechanical challenge of transitioning from planar to cylindrical geometry while maintaining the reliability advantages of LCP material
Data Source
AI summary
An electrode lead may comprise a flexible circuit that includes a planar dielectric substrate including an elongated lead substrate portion having opposing ends, an electrode carrying substrate portion disposed on one end of the lead substrate portion, and a connector substrate portion disposed on the other end of the lead substrate portion, wherein the lead substrate portion is pre-shaped into a three-dimensional structure. The flexible circuit may further include an electrically conductive trace extending from the connector substrate portion to the electrode carrying substrate portion, a first window formed in the connector substrate portion to expose the electrically conductive trace to form a connector pad, and a second window formed in the electrode carrying substrate portion to expose the electrically conductive trace to form an electrode pad. The electrode lead may further comprise a lead connector that incorporates the connector substrate portion.