Retinal Electrode Array Simultaneous Line Stimulation
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Solution Overview
Problem
Conventional visual prostheses face challenges in providing flicker-free vision with larger electrode arrays due to sequential current application, which leads to 'cross-talk' and increased power consumption, especially when using multiple current sources and hexagonal guard rings.
Innovation Solution
Applying electrical current simultaneously to electrodes in lines rather than individually, utilizing a single current source and larger electrodes with wider pulse widths, which reduces power consumption and enhances image quality by targeting lines and edges, thereby achieving lower threshold charges and localized activation of the visual cortex.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If sequential application of current to electrodes is employed in larger arrays, then the stimulation can be applied to more electrodes, but the stimulation may not be fast enough to provide flicker-free vision to the patient
Solution Approach 1:
The electrode array is divided into multiple independent groups or columns that can be stimulated simultaneously. Each group is driven by its own current source, allowing parallel stimulation of multiple electrodes rather than sequential scanning, thereby achieving both high electrode coverage and fast stimulation speeds for flicker-free vision.
Solution Approach 2:
Multiple current sources are combined to drive different groups of electrodes simultaneously. This merging of current sources enables parallel current application to multiple electrodes, increasing the effective stimulation speed while maintaining the ability to address a large number of electrodes across the array.
2Speed
If simultaneous application of current to multiple electrodes is performed, then faster stimulation is achieved, but cross-talk or current interactions between electrodes leads to enlarging of tissue areas stimulated and blurring of the resultant image
Solution Approach 1:
The electrode array is segmented into spatially separated groups or columns that are stimulated simultaneously but independently. This segmentation prevents current cross-talk between groups while maintaining fast stimulation speeds, as each group acts as an independent stimulation unit with controlled current distribution.
Solution Approach 2:
Different spatial regions or groups of electrodes are stimulated with locally optimized current parameters. Each group can have tailored current amplitude and timing to achieve precise local stimulation without affecting adjacent regions, thereby maintaining spatial precision while enabling simultaneous multi-electrode activation.
3Manufacturing precision
If hexagonal guard rings of electrodes are created to keep current focussed, then current application to central electrode is improved, but thresholds for electrical stimulation increase and total power consumption increases
Solution Approach 1:
The hexagonal guard ring structure is removed or replaced with simpler electrode configurations. Instead of using complex guard rings to control current flow, the invention employs direct current application to segmented electrode groups, eliminating the need for additional guard electrodes and reducing overall power consumption while maintaining adequate current focus through spatial segmentation.
Solution Approach 2:
The stimulation parameters such as current amplitude, pulse width, and frequency are optimized for the segmented electrode configuration. By changing these parameters to match the simplified electrode architecture, the system achieves effective stimulation with lower power consumption compared to hexagonal guard ring designs that require higher thresholds.
4Quantity of substance
If multiple current sources are used to apply current to hexagonal patterns simultaneously, then current can be applied to many electrodes at once, but specialised hardware is required increasing cost and component sizes
Solution Approach 1:
The electrode array is segmented into multiple columns or groups that can be driven by simplified current sources. This segmentation allows simultaneous stimulation of multiple electrodes using straightforward current delivery circuits, avoiding the need for complex hexagonal pattern generation hardware while maintaining the capability to address many electrodes in parallel.
Solution Approach 2:
The current sources are designed with universal functionality to drive any electrode or group of electrodes within their assigned segment. This multi-functional design simplifies the hardware architecture compared to specialized hexagonal guard ring drivers, as the same current source can adapt to different stimulation patterns and electrode configurations within its domain.
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 allows for faster stimulation, reduced power consumption, and improved image quality with a wider field of view, as it lowers the total threshold charge per pulse and impedance, enabling sharper lines and edges perception without smearing, while also overcoming the limitations of sequential techniques.
Implementation Method 1
Electrical signals are transmitted via the electrodes to the retinal nerve cells, triggering a perception of light within the patient's brain
Data Source
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Figure 3
Figure 4a~4b
AI summary
A method and apparatus is described for electrically stimulating a patient's retina with an electrode array (32) implanted in the patient's eye, wherein one or more images are captured; at least one line and/or edge in the images is determined (21), a line of electrodes in the electrode array corresponding to a detected line and/or edge is identified (24); and electrical current is applied simultaneously to electrodes of the identified line of electrodes.