Impedance-Based Electrode Assignment for Evoked Response Recording
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Solution Overview
Problem
Measuring evoked responses using implantable stimulators is challenging due to difficult morphology, long acquisition windows, and small amplitude signals with competing artifacts and background noise.
Innovation Solution
Determine a set of electrodes based on impedance measurements to differentiate between stimulating and recording electrodes, reducing interference from stimulation artifacts by designating electrodes with lower impedances for stimulation and those with minimal artifacts for recording.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the same electrodes are used for both stimulation and recording, then device complexity is reduced, but measurement precision deteriorates due to stimulation artifacts interfering with evoked response signals
Solution Approach 1:
The electrode array is segmented into distinct stimulating electrodes and recording electrodes based on impedance characteristics. This segmentation allows separate optimization of stimulation delivery and response recording functions, eliminating artifact contamination while maintaining a single integrated device.
Solution Approach 2:
Different regions of the electrode array are assigned different functional qualities - some electrodes are designated for stimulation based on their impedance properties, while others are designated for recording. This local differentiation optimizes each function's performance without requiring completely separate devices.
2Measurement precision
If impedance-based electrode designation is implemented, then measurement precision improves by reducing stimulation artifacts, but device complexity increases due to additional impedance measurement and electrode classification requirements
Solution Approach 1:
The system performs self-characterization by automatically measuring impedance values and classifying electrodes into stimulating and recording groups without external intervention. This self-service approach streamlines the setup process and reduces operational complexity despite the added measurement capabilities.
Solution Approach 2:
Impedance measurements and electrode classifications are performed in advance during an initialization phase before actual evoked response measurements begin. This preliminary action prepares the electrode designation in advance, eliminating the need for complex real-time classification during measurement.
3Measurement precision
If multiple electrodes are used for recording, then measurement precision improves, but object-generated harmful factors increase due to more stimulation artifacts from additional stimulating electrodes
Solution Approach 1:
Recording electrodes are extracted and separated from the stimulating electrode group based on their lower impedance characteristics. This extraction removes the source of stimulation artifacts from the recording path, allowing multiple recording electrodes to be used without proportionally increasing artifact contamination.
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
This approach reduces interference from stimulation artifacts, facilitating efficient data transmission and automatic identification of evoked response features, minimizing clinical analysis burden and aiding in recipient condition evaluation.
Implementation Method 1
measuring impedances for a plurality of electrodes of an implantable stimulator that is implanted within a recipient
Data Source
AI summary
An exemplary electrical status-based determination of electrodes of an implantable stimulator for measuring an evoked response may include measuring electrical statuses for each electrode included in a plurality of electrodes of an implantable stimulator that is implanted within a recipient, designating, based on the electrical statuses, a first set of one or more electrodes included in the plurality of electrodes as stimulating electrodes to be used to deliver electrical stimulation to the recipient, and designating, based on the electrical statuses, a second set of one or more electrodes included in the plurality of electrodes as recording electrodes to be used to record one or more signals representative of one or more evoked responses that occur within the recipient in response to the electrical stimulation.