Flexible Circuit Electrode Array for Retinal Stimulation
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Solution Overview
Problem
Existing neural stimulation technologies, such as retinal prostheses, face challenges in providing stable and effective electrical stimulation to the retina while minimizing pressure and preventing tissue damage, as they often apply uneven pressure and can be too bulky or invasive, leading to issues like retinal ischemia and tissue cutting.
Innovation Solution
A flexible circuit electrode array with multiple layers of metal traces and polymer layers, designed to match the curvature of the retina, featuring a polymer base layer, metal traces separated by polymer layers, and a polymer top layer, which is curved to fit the retinal shape and includes features like folds and twists to reduce pressure and prevent damage, along with a protective skirt to safeguard the tissue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rigid electrode arrays are used for retinal stimulation, then electrical contact stability is improved, but pressure on the retina increases causing tissue damage
Solution Approach 1:
The patent employs a flexible printed circuit board (FPC) as the substrate for the electrode array, replacing rigid materials like silicon or glass. This flexible substrate can conform to the curved retinal surface without applying excessive pressure, while maintaining stable electrical contact through the array of electrodes. The flexibility allows the device to adapt to the biological surface geometry, resolving the contradiction between contact stability and pressure-induced damage.
Solution Approach 2:
The electrode array is designed with a curved configuration that matches the spherical geometry of the retinal surface. This curvature ensures uniform contact across the retinal surface, distributing pressure evenly and preventing localized tissue damage while maintaining reliable electrical stimulation. The curved design allows the rigid electrode pattern to conform to the biological surface without compromising contact stability.
2Area of stationary object
If larger electrode arrays are implanted to cover more retinal area, then visual field coverage is improved, but device bulkiness and invasiveness increase
Solution Approach 1:
The patent separates the electrode array from the control electronics and power source, implanting only the thin flexible electrode array in the eye while leaving the bulkier electronic components outside. This extraction allows large-area retinal coverage with a minimally invasive implant, as the flexible FPC can be made large without proportionally increasing the implanted volume. The external components can be removed or minimized, resolving the contradiction between coverage area and device bulkiness.
Solution Approach 2:
The use of a flexible printed circuit board enables the creation of large-area electrode arrays with minimal thickness. The FPC can be scaled to cover extensive retinal areas while maintaining a thin profile that minimizes invasiveness. This flexible film technology allows the device area to increase without a corresponding increase in volume or structural bulk, resolving the contradiction between coverage and invasiveness.
3Object-affected harmful factors
If electrode arrays are made thinner to reduce invasiveness, then tissue damage is minimized, but mechanical stability and electrical contact reliability decrease
Solution Approach 1:
The patent uses a composite structure combining the flexible FPC substrate with an array of conductive electrodes and insulating layers. This composite design provides mechanical stability through the layered construction while maintaining thin overall thickness. The FPC substrate offers structural support, the electrodes provide electrical functionality, and the insulating layers prevent short circuits, creating a stable yet thin device that minimizes tissue damage while ensuring reliability.
Solution Approach 2:
The curved configuration of the electrode array on the flexible substrate distributes mechanical stresses evenly across the device and retinal surface. This curvature prevents stress concentration that would compromise mechanical stability in thin devices, while the flexible nature allows the thin array to conform to the retina without causing damage. The curved geometry thus enhances both stability and tissue compatibility.
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
The flexible circuit electrode array provides stable and efficient neural stimulation by reducing pressure on the retina, minimizing tissue damage, and ensuring effective electrical contact, thus enhancing the ability to restore vision in visually impaired individuals.
Implementation Method 1
A flexible circuit electrode array is provided with more than one layer of metal traces
Implementation Method 2
more than one layer of metal traces, separated by polymer layers, deposited on said polymer base layer, including electrodes suitable to stimulate neural tissue
Implementation Method 3
designed to match the curvature of the retina, featuring a polymer base layer, metal traces separated by polymer layers, and a polymer top layer, which is curved to fit the retinal shape
Data Source
Figure 1
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Figure 3A~3E
AI summary
A flexible circuit electrode array with more than one layer of metal traces comprising: a polymer base layer; more thanone layer of metal traces, separated by polymer layers, deposited on said polymer base layer, including electrodes suitable to stimulate neural tissue; and a polymer top layer deposited on said polymer base layer and said metal traces. Polymer materials are useful as electrode array bodies for neural stimulation. They are particularly useful for retinal stimulation to create artificial vision, cochlear stimulation to create artificial hearing, or cortical stimulation many purposes. The pressure applied against the retina, or other neural tissue, by an electrode array is critical. Too little pressure causes increased electrical resistance, along with electric field dispersion. Too much pressure may block blood flow.