Bidirectional Pulse Current Circuit for Safe Retinal Stimulation
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Solution Overview
Problem
Conventional artificial retinas and neural stimulation devices face limitations in stimulating retinal bipolar cells effectively and ensuring safe charge levels during neural stimulation, leading to inadequate resolution and potential tissue damage due to net charges on ganglion and bipolar cells.
Innovation Solution
A pulse current generation circuit with a current generator capable of producing bidirectional pulse currents of varying precision, combined with a charge compensation circuit that detects and balances charge amounts within safe ranges, allowing for effective stimulation of both ganglion and bipolar cells while preventing tissue damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a wide pulse width is used to stimulate bipolar cells, then the stimulation resolution is improved, but the charge amount may exceed the safe range causing tissue damage
Solution Approach 1:
The circuit dynamically adjusts the pulse current amplitude based on the pulse width. When a wide pulse width is selected to stimulate bipolar cells, the circuit automatically reduces the current amplitude to ensure the total charge remains within safe limits, thereby maintaining both high stimulation resolution and tissue safety
Solution Approach 2:
The system changes the parameters of the pulse current (amplitude and width) according to different stimulation needs. By adjusting these parameters dynamically, the circuit can achieve precise stimulation of bipolar cells while controlling the charge amount to prevent tissue damage
2Object-affected harmful factors
If the amplitude of pulse current is increased to ensure safe charge levels, then tissue safety is improved, but the ability to stimulate bipolar cells effectively is reduced
Solution Approach 1:
The circuit dynamically adjusts the pulse current amplitude based on the pulse width. When a wide pulse width is selected to stimulate bipolar cells, the circuit automatically reduces the current amplitude to ensure the total charge remains within safe limits, thereby maintaining both high stimulation resolution and tissue safety
Solution Approach 2:
The charge compensation circuit monitors the charge amount delivered to the tissue and provides feedback control. When the charge approaches safe limits, the circuit automatically adjusts the pulse parameters to prevent excessive charge accumulation, ensuring both safety and effectiveness
3Reliability
If a capacitor with larger capacitance is used in the RC circuit to balance charges, then charge balance performance is improved, but the circuit area increases making integration difficult
Solution Approach 1:
The patent changes the working parameters of the existing capacitor (using different voltage levels and timing sequences) to achieve better charge balance performance without increasing the physical capacitance value or circuit area, enabling effective charge compensation in a compact integrated circuit
Data Source
AI summary
A pulse current generation circuit (100) for neural stimulation includes an analogue signal receiving device (101) for receiving an analogue signal; an analogue-to-digital converter (102) for converting the analogue signal into a digital control signal; a current signal controller (103) for producing, according to the digital control signal, pulse current parameters for generating bidirectional pulse current signals; and a current generator (104) for generating, according to the pulse current parameters, bidirectional pulse current signals for neural stimulation, and the current generator can generate pulse currents of different precisions according to the pulse current parameters. In addition, the present invention further relates to a charge compensation circuit, a charge compensation method, and an implantable electrical retina stimulator using the pulse current generation circuit or the charge compensation circuit.