Three-Phase Neural Stimulation for Orthogonal Artefact Rejection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in neuromodulation systems is accurately detecting neural responses, such as compound action potentials (CAPs), amidst significant stimulus artefacts, particularly in implantable devices with limited power budgets and close electrode proximity, which complicates the design of measurement amplifiers.
Innovation Solution
A method and device utilizing a neural stimulus with at least three components, including temporal phases and spatial poles, where the first and third charges are unequal to minimize artefact, employing a vector detector to achieve orthogonal alignment of artefact and neural response vectors, and optionally combining with charge balancing and adaptive adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a neural stimulus is applied to evoke a compound action potential, then the neural response can be detected, but significant stimulus artefact is generated that complicates accurate detection
Solution Approach 1:
The stimulus is divided into multiple discrete phases (first phase, second phase, third phase) with different polarities and charge magnitudes. This segmentation allows the artefact components from each phase to be differentiated and selectively cancelled in the recorded signal, improving the precision of neural response detection while managing the artefact generated by each stimulus phase.
2Reliability
If the electrode array is positioned close to the neural pathway for effective stimulation, then the therapeutic effect is improved, but the stimulus artefact at recording electrodes increases
Solution Approach 1:
The stimulus waveform employs asymmetric phase structures where the first and third phases have different charge magnitudes (Q1 ≠ Q3) compared to conventional symmetric biphasic pulses. This asymmetry creates a specific artefact pattern that can be distinguished and cancelled against the neural response signal, allowing close electrode placement for reliable therapeutic effect while reducing artefact interference at recording electrodes.
3Reliability
If charge balancing is implemented in the stimulus waveform, then tissue safety is improved, but the artefact cancellation capability is reduced
Solution Approach 1:
The stimulus waveform parameters are specifically configured with unequal charges in the first and third phases (Q1 ≠ Q3) while maintaining overall charge balance for tissue safety. This parameter change allows the system to achieve both tissue safety through charge balancing and artefact cancellation through the asymmetric phase structure, resolving the contradiction between these two requirements.
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
Significantly reduces stimulus artefact, enabling accurate detection of neural responses with improved signal-to-noise ratios, even in implantable devices with limited power, by optimizing the stimulus waveform and detector settings.
Implementation Method 1
a first stimulus component delivers a first charge which is unequal to a third charge delivered by a third stimulus component, the first charge and third charge being selected so as to give rise to reduced artefact at recording electrodes
Implementation Method 2
detecting the neural response in the recording with a vector detector; wherein a correlation delay of the vector detector, and the first charge and third charge of the stimulus, have values which cause a produced artefact vector to be non-parallel to an evoked neural response vector
Data Source
AI summary
A neural stimulus comprises at least three stimulus components, each comprising at least one of a temporal stimulus phase and a spatial stimulus pole. A first stimulus component delivers a first charge which is unequal to a third charge delivered by a third stimulus component, and the first charge and third charge are selected so as to give rise to reduced artefact at recording electrodes. In turn this may be exploited to independently control a correlation delay of a vector detector and an artefact vector to be non-parallel or orthogonal.