Retinal Prosthesis Safety Circuit for Neural Stimulation
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Solution Overview
Problem
Existing neural stimulation technologies face challenges in preventing overstimulation and unbalanced stimulation, which can cause damage to neural tissue and electrodes, and there is a need to identify defective electrodes to avoid further damage.
Innovation Solution
A retinal prosthesis system with a flexible circuit electrode array and an integrated circuit for detecting excessive direct current flow, charge buildup, and electrode impedance, along with methods to identify defective electrodes and ensure safe stimulation parameters, including balanced biphasic current pulses and hybrid bipolar stimulation modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If neural stimulation is applied to restore vision in visually impaired patients, then visual perception is improved, but risk of neural tissue damage increases due to overstimulation or unbalanced stimulation
Solution Approach 1:
The patent implements safety check circuits that continuously monitor stimulation parameters and provide feedback to the control system. When abnormal conditions are detected (such as unbalanced charge or excessive current), the system automatically adjusts or terminates stimulation to prevent neural tissue damage while maintaining effective visual stimulation.
Solution Approach 2:
The patent performs preliminary safety checks before and during neural stimulation by monitoring charge balance, current limits, and electrode impedance. These preventive measures are implemented in advance to identify potential hazards before they cause neural tissue damage, ensuring safe operation throughout the stimulation process.
2Duration of action of stationary object
If continuous neural stimulation is provided to maintain visual function, then visual perception is maintained, but risk of electrode damage and charge buildup increases
Solution Approach 1:
The patent implements periodic safety checks during continuous stimulation by monitoring charge buildup and electrode impedance at regular intervals. The system uses periodic biphasic pulses with controlled duration and amplitude, and performs intermediate measurements to detect electrode degradation or charge accumulation that could lead to damage.
Solution Approach 2:
The patent uses feedback mechanisms to monitor electrode impedance and charge balance continuously during prolonged stimulation. When thresholds are approached or exceeded, the system automatically reduces stimulation intensity or terminates pulses to prevent electrode damage while maintaining visual function as long as safely possible.
3Illumination intensity
If high current stimulation is used to produce brighter phosphenes and improve visual perception, then illumination intensity is improved, but risk of overheating and tissue damage increases
Solution Approach 1:
The patent maintains continuous monitoring of stimulation parameters and tissue response during visual stimulation. By continuously adjusting current amplitude based on safety checks and physiological feedback, the system optimizes phosphene brightness while preventing excessive temperature rise through real-time control of stimulation intensity.
Solution Approach 2:
The patent dynamically adjusts stimulation parameters including current amplitude, pulse duration, and frequency based on safety constraints and desired visual output. By changing these parameters within safe limits, the system achieves adequate phosphene brightness without exceeding thermal safety thresholds that would cause tissue damage.
4Object-affected harmful factors
If safety check circuits are added to monitor stimulation parameters, then neural tissue protection is improved, but device complexity increases
Solution Approach 1:
The patent integrates safety check functions directly into the existing neural stimulation device circuitry by combining monitoring, measurement, and control functions with the stimulation generation circuit. This merging approach provides comprehensive neural tissue protection while minimizing additional device complexity through functional integration rather than separate added components.
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 system effectively prevents neural and electrode damage by detecting and mitigating excessive current, charge imbalance, and identifying defective electrodes, ensuring safe and effective neural stimulation.
Implementation Method 1
an integrated circuit for detecting excessive direct current flow
Implementation Method 2
detecting excessive current, charge imbalance
Implementation Method 3
detecting excessive current, charge imbalance, and identifying defective electrodes
Implementation Method 4
passages of current causes changes in electrical potentials across visual neuronal membranes, which can initiate visual neuron action potentials
Data Source
AI summary
In electrically stimulating neural tissue it is important to prevent over stimulation and unbalanced stimulation, which would cause damage to the neural tissue, the electrode, or both. It is critical that neural tissue is not subjected to any direct current or alternating current above a safe threshold. Further, it is important to identify defective electrodes, as continued use may result in neural damage and further electrode damage. The present invention presents system and stimulator control mechanisms to prevent damage to neural tissue.