Three-Phase Neural Stimulation for Reduced Artefact Detection

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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 implanted devices with limited power budgets and close electrode proximity, which complicates amplifier design and power consumption.

Innovation Solution

A method and device using a neural stimulus with at least three components, each with a temporal phase and spatial pole, where the first and third charges are unequal to minimize artefact, employing a vector detector to align the artefact vector orthogonally to the neural response vector, and optionally combining with charge balancing and adaptive adjustments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If electrical pulse is applied to neural tissue to generate therapeutic effect, then neural response is evoked, but stimulus artefact is generated that complicates detection of neural response

Engineering Contradiction:

Improvetherapeutic effectVSAvoidneural response detection

Core Design Contradiction:

ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The stimulus pulse is segmented into multiple phases (first phase, second phase, third phase) with different charge magnitudes. The first and third phases have unequal charges, while the second phase provides charge balancing. This segmentation allows the stimulus to evoke neural response while creating artefact patterns that can be distinguished from the neural response through vector detection.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The stimulus waveform uses asymmetric charge distribution across phases, specifically making the first and third phase charges unequal. This asymmetry creates a characteristic artefact vector that, when combined with appropriate correlation delay, becomes orthogonal to the neural response vector, enabling clear separation of signal from artefact in the detection process.

Inventive Principle:

Principle #4Asymmetry

2Speed

If recording electrodes are placed close to stimulus site, then neural response can be detected earlier, but stimulus artefact increases significantly

Engineering Contradiction:

Improveresponse detection timeVSAvoidstimulus artefact

Core Design Contradiction:

SpeedVSObject-generated harmful factors

Solution Approach 1:

The invention changes the temporal and charge parameters of the stimulus waveform by using multiple phases with unequal charge magnitudes. This parameter modification allows close electrode placement to be used (enabling fast detection) while the specific phase structure and charge distribution minimize the artefact contamination in the early response period.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If high stimulation currents are used, then neural response signal strength increases, but stimulus artefact amplitude also increases

Engineering Contradiction:

Improvesignal-to-noise ratioVSAvoidstimulus artefact

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The invention converts the harmful stimulus artefact into a beneficial signal by using unequal charges in the first and third phases. This creates a predictable artefact pattern that, when processed with appropriate correlation delay, becomes orthogonal to the neural response. The artefact thus provides a reference that helps isolate and detect the neural response more accurately.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

4Reliability

If charge balanced biphasic stimulus is used, then tissue safety is improved, but artefact reduction is limited

Engineering Contradiction:

Improvetissue safetyVSAvoidstimulus artefact

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The stimulus is divided into three phases instead of two, with the first and third phases having unequal charges and the second phase providing charge balancing. This three-phase segmentation maintains tissue safety through charge balancing while creating a more complex artefact pattern that can be better separated from the neural response using vector detection with correlation delay.

Inventive Principle:

Principle #1Segmentation

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 ratio, optimizing power usage, and enhancing neuromodulation effectiveness.

Implementation Method 1

A neuromodulation system applies an electrical pulse to neural tissue in order to generate a therapeutic effect

Methodology Applied

Scientific EffectNeural stimulation:

Implementation Method 2

employing a vector detector to align the artefact vector orthogonally to the neural response vector

Methodology Applied

Scientific EffectVector detection:

Data Source

PatentUS12433528B2Neural stimulation for reduced artefact

Publication Date: 2025.10.07 SALUDA MEDICAL PTY LTD

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.