Tripolar Neuromodulation Sensing for eCAP Artifact Cancellation
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Solution Overview
Problem
Existing neuromodulation devices face challenges in accurately monitoring the effectiveness of nerve stimulation due to high noise levels and interference from stimulation artefacts, especially when targeting neurovascular bundles, which complicates the measurement of evoked compound action potentials (eCAPs) and impedance.
Innovation Solution
The use of a tripolar electrode configuration with bipolar alternating stimulation pulses and a central sensing electrode, combined with signal processing techniques like averaging and artefact cancellation, to enhance the signal-to-noise ratio of eCAP measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct monitoring of neural response is implemented, then feedback on neuromodulation efficacy is improved, but signal noise and stimulation artefacts increase
Solution Approach 1:
The patent introduces an intermediary signal processing system that includes artifact cancellation algorithms and template matching techniques. These intermediaries process the raw neural signals by subtracting estimated stimulation artifacts and enhancing the eCAP components, thereby enabling accurate measurement despite the presence of noise and artefacts.
Solution Approach 2:
The patent replaces direct mechanical/electrical signal acquisition with sophisticated digital signal processing techniques. Instead of relying solely on clean electrical signals, the system uses computational methods such as template matching, autocorrelation analysis, and artifact subtraction to extract neural responses from noisy measurements.
2Reliability
If monitoring systems are added to measure neural response, then feedback capability is improved, but device complexity increases
Solution Approach 1:
The patent integrates multiple functions into existing neuromodulation devices. The same electrode array used for delivering stimulation also serves as the sensing array for monitoring neural responses. Additionally, the signal processing system performs multiple tasks including artifact cancellation, eCAP extraction, and efficacy assessment using a unified computational framework.
Solution Approach 2:
The monitoring system leverages the device's own stimulation artifacts and neural responses to generate feedback. The system uses the stimulation pulses themselves as templates for artifact cancellation and employs the evoked responses as the basis for efficacy assessment, allowing the device to self-monitor without external equipment.
3Reliability
If high stimulation amplitude is used to ensure target engagement, then neuromodulation effectiveness is improved, but measurement noise increases
Solution Approach 1:
The patent applies preliminary anti-action by pre-calculating and subtracting stimulation artifacts from the measured signals. The system anticipates the artifact components based on stimulation parameters and uses template matching to predict and remove these artifacts before eCAP analysis, thereby preserving measurement precision even at high stimulation amplitudes.
Solution Approach 2:
The patent dynamically adjusts processing parameters based on stimulation intensity. The template matching algorithms adapt their sensitivity thresholds, the artifact cancellation weights are optimized for each stimulation level, and the signal processing gain is adjusted to maintain optimal eCAP detection across varying stimulation amplitudes.
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 allows for precise measurement of evoked compound action potentials and impedance changes, providing accurate feedback on neuromodulation efficacy and target engagement, even in noisy environments.
Implementation Method 1
the electrodes may activate or inhibit nerve activity in the anatomy, which can be measured with sensors within the devices by detecting evoked compound action potentials (eCAP) and/or impedance that result from the electrical stimulation of the nerves
Implementation Method 2
detecting evoked compound action potentials (eCAP) and/or impedance that result from the electrical stimulation of the nerves
Data Source
AI summary
A neuromodulation device for measuring an evoked response comprising a first electrode; a second electrode, wherein the first and second electrodes are alternately configured as a stimulation electrode; a sensing electrode for sensing an evoked response to a stimulus pulse; and a controller configured to measure an evoked response at the sensing electrode after a stimulus pulse at a first stimulation electrode configuration and after a stimulus pulse at a second alternate stimulation electrode configuration, and to add said pair of measurements.