ECAP Sensing Circuit Calibration Using Stored Voltage Offsets
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Solution Overview
Problem
Existing medical devices struggle to accurately measure evoked compound action potentials (ECAPs) to adjust electrical stimulation therapy effectively, leading to suboptimal therapeutic outcomes due to variations in nerve tissue response.
Innovation Solution
A system with calibration circuitry for sensing circuitry to measure ECAP signals by storing voltages at calibration capacitors and switching out calibration switches to determine sensing signals, allowing for adjustment of stimulation parameters based on ECAP measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If calibration circuitry is added to sensing circuitry to accurately measure ECAP signals, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by performing calibration measurements before actual ECAP signal measurements. The calibration circuitry stores baseline voltage values in capacitors during a calibration phase, then uses these pre-stored values to compensate for offset errors during subsequent measurements. This preliminary calibration action enables accurate measurements without requiring complex real-time correction mechanisms.
Solution Approach 2:
The patent uses calibration capacitors as intermediary elements that store offset voltage values. These capacitors act as mediators between the sensing circuitry and the measurement process, allowing the system to compensate for errors by comparing current measurements against the stored calibration values. This intermediary approach simplifies the overall circuit design compared to implementing complex real-time error correction algorithms.
2Reliability
If calibration capacitors and switches are used to store and prevent changing of calibration voltages, then reliability is improved, but device complexity increases
Solution Approach 1:
The calibration voltages are determined and stored in capacitors during an initial calibration phase before normal operation. This preliminary action ensures that stable reference values are established beforehand, which then remain constant during subsequent measurements. The switches are configured to maintain these pre-stored values, ensuring reliability without requiring continuous active management during operation.
Solution Approach 2:
The patent replaces mechanical or continuously active stabilization mechanisms with electrical capacitors that naturally hold voltage values. Instead of using complex active control circuits to maintain calibration voltages, the system uses passive capacitive storage combined with switch configuration, simplifying the overall system while maintaining voltage stability throughout the measurement process.
Data Source
AI summary
A system for providing therapy to a patient includes stimulation generation circuitry, sensing circuitry, and processing circuitry. The processing circuitry is configured to cause storage of a first voltage at a first terminal at a first calibration capacitor and storage of a second voltage at a second terminal at a second calibration capacitor. The processing circuitry is configured to switch out a first calibration switch to prevent the first voltage stored at the first calibration capacitor from changing and switch out a second calibration switch to prevent the second voltage stored at the second calibration capacitor from changing and determine, with the sensing circuitry, a sensing signal based on the first voltage offset by a first calibration voltage stored by the first capacitor and based on the second voltage offset by a second calibration voltage stored by the second capacitor.