Current Source-Sink Calibration in Stimulating Electrodes
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Solution Overview
Problem
Current stimulating medical devices face challenges in maintaining accurate current matching between sources and sinks over time due to operational parameter drift, which can lead to toxic product accumulation and reduced device safety and effectiveness.
Innovation Solution
In situ calibration of current sources and sinks using p-type and n-type Digital-to-Analog Converters (DACs) with a calibration arrangement that compares and adjusts the currents to ensure matching, reducing the risk of toxic product accumulation and maintaining device safety and effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current sources and sinks are used to deliver electrical stimulation over time, then therapeutic effect is achieved, but operational parameter drift causes current matching degradation and toxic product accumulation
Solution Approach 1:
The patent applies preliminary action by performing calibration of current sources and sinks before normal operation. A calibration arrangement compares currents from p-type and n-type DACs and stores calibration values that are applied during operation to pre-compensate for drift, ensuring accurate current matching is established in advance and maintained throughout the device lifetime.
Solution Approach 2:
The patent implements feedback through a calibration arrangement that continuously or periodically compares the actual currents from p-type and n-type DACs, detects deviations from matching conditions, and adjusts calibration values accordingly. This closed-loop feedback mechanism corrects drift and maintains current matching accuracy over the device operational lifetime.
2Productivity
If p-type and n-type Digital-to-Analog Converters are used for current control, then current delivery capability is achieved, but parameter drift occurs over time causing current mismatch
Solution Approach 1:
The patent applies parameter changes by introducing calibration values that modify the operational parameters of p-type and n-type DACs. These calibration values adjust the transfer characteristics of the DACs to compensate for drift, maintaining stable current delivery despite changes in component parameters over time and temperature.
Solution Approach 2:
The calibration arrangement provides feedback by monitoring the actual current output of p-type and n-type DACs and adjusting calibration parameters to maintain matching. This feedback loop detects parameter drift and automatically corrects it by modifying DAC control parameters.
3Adaptability or versatility
If current is delivered through electrodes to stimulate tissue, then therapeutic function is achieved, but toxic species are generated if voltage remains elevated too long
Solution Approach 1:
The patent implements feedback through calibration that ensures accurate current matching between sources and sinks, preventing voltage elevation that would generate toxic species. The calibration arrangement monitors current balance and adjusts parameters to maintain safe operating conditions, providing feedback control that prevents harmful effects.
Solution Approach 2:
The patent applies preliminary anti-action by pre-calibrating current sources and sinks to ensure accurate matching before operation begins. This preliminary calibration establishes correct current balance that prevents voltage elevation and toxic species generation throughout device operation, countering potential harmful effects before they can occur.
Data Source
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AI summary
A stimulating medical device, comprising a plurality of electrodes, and a current source and a current sink connected to each one of the electrodes. The medical device also comprises a calibration arrangement configured to compare the current provided by a selected one of the current sources to the current sunk by a selected one of the current sinks, and configured to adjust an operational parameter of at least one of the source and sink based on said comparison such that the current provided by the selected current source is substantially the same as the current sunk by the current sink.