Cochlear Implant ECAP Recording Using Dual Electrode Artifact Subtraction
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Solution Overview
Problem
Cochlea implant systems face challenges in calibrating electrical stimulations due to contamination by artifacts and background noise in Evoked Compound Action Potential (ECAP) recordings, limiting the accuracy of objective measurements and trustworthiness of ECAP thresholds.
Innovation Solution
A method involving an electrode array with a stimulator electrode and two recording electrodes, where the second recording electrode is positioned further away to record a secondary cochlea response signal with negligible ECAP, allowing for the determination of the main electrically evoked compound action potential by subtracting artifacts from the primary response signal using a nonlinear time-variant function estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ECAP recording is performed using conventional single-electrode approach, then the ECAP signal can be obtained, but the recording is heavily contaminated by stimulation artifacts and background noise
Solution Approach 1:
The patent divides the recording function across multiple electrodes (first recording electrode closer to stimulator, second recording electrode farther away). The first electrode captures both ECAP and artifact, while the second electrode captures primarily artifact. This segmentation allows separate measurement and subsequent subtraction of artifacts from the primary recording, significantly improving ECAP signal quality.
Solution Approach 2:
The patent extracts the artifact component from the contaminated ECAP recording by using the second recording electrode that primarily captures artifact. This extracted artifact signal is then subtracted from the first recording electrode's output, removing the harmful artifact component while preserving the ECAP signal.
2Measurement precision
If masking-based approach is used to remove artifacts, then some artifact reduction is achieved, but linear and nonlinearity effects remain due to electrical interactions between pulses
Solution Approach 1:
The patent introduces a third electrode (second recording electrode) as an intermediary that specifically captures the artifact component. This intermediary measurement allows for accurate subtraction of artifacts from the primary ECAP recording, addressing the limitation of masking-based approaches that leave residual electrical interaction effects.
3Measurement precision
If polarity-inversion approach is used for ECAP de-artefacting, then artifact reduction is attempted, but neither neural cell activation nor remaining artifact is identical in cathodic and anodic stimulations
Solution Approach 1:
The patent applies local quality by placing recording electrodes at different locations with different characteristics. The first recording electrode (closer to stimulator) has different recording properties than the second recording electrode (farther away), allowing each electrode to capture different proportions of ECAP and artifact, enabling accurate artifact separation without relying on polarity-inversion assumptions.
4Measurement precision
If multiple recording electrodes are used to reduce artifacts, then artifact reduction is improved, but the device complexity increases
Solution Approach 1:
The patent uses a minimal number of electrodes (just two recording electrodes plus the stimulator) to achieve the artifact reduction goal. This partial action approach provides sufficient artifact removal capability without the excessive complexity that would result from using more electrodes, maintaining an optimal balance between performance and simplicity.
Data Source
AI summary
A method and a system for measuring a main electrically evoked compound action potential is described. The system may comprise a cochlea implant system which includes an electrode array, and where the electrode array includes at least a stimulator electrode, a first recording electrode and a second recording electrode, and where the first recording electrode is arranged closer to the stimulator electrode than the second recording electrode, a processor electrically in communication with the cochlea implant system. The processor may be configured to apply a stimulation including a first primary stimulation paradigm to the stimulator electrode and to receive a first primary cochlea response signal recorded by the first recording electrode while applying the stimulation, and to receive a first secondary cochlea response signal recorded by the second recording electrode, and determine the main electrically evoked compound action potential based on a difference between the first primary cochlea response signal and the first secondary cochlea response signal.