Flexible Circuit Electrode Array Adhesion via Primer Layer
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Solution Overview
Problem
Existing flexible circuit electrode arrays for biomedical implants, such as retinal prostheses, face challenges in achieving optimal adhesion between polymer layers and maintaining insulation while being curved to match the spherical shape of the retina, which can lead to increased electrical resistance and potential tissue damage.
Innovation Solution
A method of manufacturing a flexible circuit electrode array involving the activation of a base polymer layer followed by a top polymer layer, with a metal layer applied as an adhesion aid, and using a thermoplastic polymer to curve the array in multiple molds matching the retina's shape, combined with silicone bumpers to protect the tissue from sharp edges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a flexible circuit electrode array is curved to match the spherical shape of the retina, then contact with the retina is improved, but adhesion between polymer layers deteriorates and electrical resistance increases
Solution Approach 1:
The patent applies a primer layer to the first polymer layer before applying the second polymer layer. This preliminary action enhances the adhesion between polymer layers before the array is curved to match the retina's spherical shape, preventing delamination while maintaining the necessary curvature for retinal contact.
Solution Approach 2:
The patent uses a composite structure with multiple polymer layers (first polymer layer, second polymer layer) and an intermediate primer layer. This composite material approach allows the array to maintain both flexibility for curving to match the retina and sufficient structural integrity to prevent layer separation during curvature.
2Ease of operation
If a flexible circuit electrode array is curved to match the spherical shape of the retina, then contact with the retina is improved, but electrical resistance increases
Solution Approach 1:
The patent applies a primer layer to the first polymer layer before applying the second polymer layer. This preliminary action enhances the adhesion between polymer layers before the array is curved to match the retina's spherical shape, preventing delamination while maintaining the necessary curvature for retinal contact.
Solution Approach 2:
The patent uses a composite structure with multiple polymer layers (first polymer layer, second polymer layer) and an intermediate primer layer. This composite material approach allows the array to maintain both flexibility for curving to match the retina and sufficient structural integrity to prevent layer separation during curvature.
3Manufacturing precision
If the flexible circuit electrode array is made flat for manufacturing, then manufacturing precision is improved, but tissue damage from sharp edges increases when curved
Solution Approach 1:
The patent applies a primer layer to the first polymer layer before applying the second polymer layer. This preliminary action enhances the adhesion between polymer layers before the array is curved to match the retina's spherical shape, preventing delamination while maintaining the necessary curvature for retinal contact.
Solution Approach 2:
The patent uses a composite structure with multiple polymer layers (first polymer layer, second polymer layer) and an intermediate primer layer. This composite material approach allows the array to maintain both flexibility for curving to match the retina and sufficient structural integrity to prevent layer separation during curvature.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances adhesion and insulation properties, reduces pressure-related tissue damage, and ensures consistent contact with the retina, improving the electrical performance and biocompatibility of the electrode array.
Implementation Method 1
an adhesion promoter is applied to the first polymer layer prior to application of the second polymer layer
Implementation Method 2
heating the flexible circuit in multiple molds, each with a decreasing radius
Data Source
Figure 1
Figure 2
Figure 3A~3E
AI summary
A method for manufacturing a flexible circuit electrode array, comprising: a) depositing a metal trace layer containing a base coating layer, a conducting layer and a top coating layer on said insulator polymer base layer; b) applying a layer of photoresist on said metal trace layer and patterning said metal trace layer and forming metal traces on said insulator polymer base layer; c) activating said insulator polymer base layer and depositing a top insulator polymer layer and forming one single insulating polymer layer with said base insulator polymer layer; d) applying a thin metal layer and a layer of photoresist on the surface of said insulator polymer layer and selective etching said insulator layer and said top coating layer to obtain at least one via; and e) filling said via with electrode material. A layer of polymer is laid down. A layer of metal is applied to the polymer and patterned to create electrodes and leads for those electrodes. A second layer of polymer is applied over the metal layer and patterned to leave openings for the electrodes, or openings are created later by means such as laser ablation. Hence the array and its supply cable are formed of a single body. Alternatively, multiple alternating layers of metal and polymer may be applied to obtain more metal traces within a given width. The method provides an excellent adhesion between the polymer base layer and the polymer top layer and insulation of the trace metals and electrodes.