Subretinal Prosthetic Device Zigzag Electrode Crosstalk Reduction
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Solution Overview
Problem
Subretinal prostheses face issues with image blurring due to crosstalk caused by currents stimulating unintended bipolar cells, resulting in lower resolution compared to epiretinal prostheses, despite having a greater number of pixels.
Innovation Solution
A subretinal prosthetic device with a zigzag pattern of stimulating electrodes and a hexagonal scanning array, where adjacent electrodes act as a return electrode, reducing crosstalk by dynamically switching and scanning at a frequency of at least 50 Hz to prevent unnecessary stimulation of bipolar cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a subretinal prosthesis with a large number of photodiode pixels is used, then the pixel quantity is improved, but image blurring occurs due to crosstalk between adjacent electrodes
Solution Approach 1:
The prosthesis array is divided into scanning groups where only one group is actively stimulated at a time while adjacent groups serve as return electrodes. This temporal and spatial segmentation prevents crosstalk between adjacent electrodes by isolating the active stimulation region, thereby maintaining high resolution despite having a large total number of pixels.
Solution Approach 2:
The system dynamically switches between different scanning groups at a frequency of at least 50 Hz, creating a moving pattern of active and return electrodes. This dynamic switching prevents static crosstalk accumulation and allows the system to maintain both high pixel quantity and high image resolution through temporal multiplexing.
2Measurement precision
If adjacent electrodes are used as return electrodes to reduce crosstalk, then measurement precision is improved, but device complexity increases due to switching requirements
Solution Approach 1:
The system employs periodic scanning of electrode groups at frequencies of at least 50 Hz, creating a rhythmic pattern of active and return electrode assignments. This periodic operation simplifies the control logic compared to arbitrary switching, as it follows a predictable temporal pattern that reduces the complexity of the switching control system while maintaining high resolution.
3Adaptability or versatility
If external camera and wireless transmission are used in epiretinal prosthesis, then adaptability is improved, but loss of information occurs due to external image processing
Solution Approach 1:
The invention extracts the photodetection function from external devices and integrates it directly into the retinal prosthesis through photodiodes implanted in the retina. This eliminates the need for external cameras and wireless transmission systems, thereby removing the intermediate signal processing step that causes information loss while maintaining adaptability through direct retinal stimulation.
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
Significantly reduces crosstalk and achieves optimized resolution for arrays with more than 1,000 pixels, providing high-resolution visual information similar to epiretinal prostheses without distorting images.
Implementation Method 1
The photodiode array performs a function similar to that of complementary metal-oxide semiconductor (CMOS) image sensors
Data Source
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AI summary
A subretinal prosthetic device includes a substrate provided under a retina, a return electrode for receiving a current such that a ground is formed on the substrate, a plurality of stimulating electrodes provided on the substrate and for generating an active potential to an optic nerve in response to external visual information projected onto the retina, and a switch for controlling the current between each of the plurality of stimulating electrodes and the return electrode. The switch is connected between the plurality of stimulating electrodes and the return electrode to ground the plurality of stimulating electrodes to the return electrode in response to an on or off control signal.