Flexible Cortical Electrode Array for Visual Prosthesis
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Solution Overview
Problem
Current visual prostheses, particularly those targeting the visual cortex, face challenges in long-term stability and invasiveness, with penetrating microelectrodes degrading due to scar tissue formation and requiring higher stimulation thresholds, while surface electrodes require higher charge densities for phosphene generation, limiting their effectiveness for widespread blindness cases.
Innovation Solution
A visual prosthesis with a flexible electrode array implanted in the Calcarine Sulcus of the visual cortex, utilizing a polymer-based flexible circuit with platinum electrodes, designed for minimal invasiveness and chronic stimulation, capable of delivering lower charge requirements for phosphene generation, and adaptable to the cortical surface with a hermetic package for implantation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If penetrating microelectrodes are used to stimulate the visual cortex, then phosphene generation threshold is reduced, but long-term stability deteriorates due to scar tissue formation and electrode degradation
Solution Approach 1:
The electrode array is divided into multiple independent microelectrodes distributed across the cortical surface, allowing selective stimulation of specific neural populations while distributing mechanical stress and scar tissue formation across multiple discrete contact points rather than requiring a single large penetrating electrode
Solution Approach 2:
A flexible polymer-based substrate supports the electrode array, allowing it to conform to the curved surface of the visual cortex and accommodate brain movement and scar tissue formation without losing electrical contact or causing mechanical damage
2Object-affected harmful factors
If surface electrodes are used to stimulate the visual cortex, then invasiveness is reduced, but charge density requirements increase for phosphene generation
Solution Approach 1:
The electrode array incorporates multiple discrete microelectrodes with varying sizes and spacing optimized for local neural stimulation, allowing lower charge density at each contact point while maintaining overall effectiveness through distributed stimulation across the cortical surface
Solution Approach 2:
The electrode array combines conductive materials with the polymer substrate to create a composite structure that maintains electrical efficiency while providing mechanical flexibility and biocompatibility, reducing the charge density required for effective stimulation
3Manufacturing precision
If a rigid electrode array is implanted in the visual cortex, then manufacturing precision is improved, but adaptability to cortical surface deteriorates
Solution Approach 1:
The electrode array is fabricated on a flexible polymer substrate that can be bent and conform to the curved surface of the visual cortex, allowing precise electrode placement and maintained electrical contact despite the flexible nature of the implant
Solution Approach 2:
The flexible electrode array can dynamically adapt its shape and position to match the cortical surface contours and accommodate brain movement, whereas a rigid array would maintain a fixed geometry that conflicts with the dynamic nature of the brain
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 solution provides a stable and less invasive means of stimulating the visual cortex, potentially restoring vision with lower charge requirements, addressing the limitations of existing technologies by ensuring long-term functionality and reduced risk of adverse events.
Implementation Method 1
Neural tissue can be artificially stimulated and activated by prosthetic devices that pass pulses of electrical current through electrodes on such a device. The passage of current causes changes in electrical potentials across neuronal membranes, which can initiate neuron action potentials
Data Source
AI summary
The present invention is a visual prosthesis adapted for implantation in the brain, and more particularly with an electrode array adapted for implantation in the Calcarine Sulcus of the visual cortex. The electrode array of the invention has electrodes on each side and spaced appropriately for the Calcarine Sulcus and driven by an electronic circuit within a hermetic package small enough to be implanted with a skull.