Reference Electrode Selection for Stable Evoked Neural Measurement
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Solution Overview
Problem
Existing neuromodulation systems face challenges in maintaining appropriate neural recruitment and energy efficiency due to electrode migration, postural changes, and differences in neural anatomy, leading to ineffective or uncomfortable stimulation, particularly in applications like spinal cord and sacral nerve stimulation.
Innovation Solution
A method and system for configuring electrodes in an electrode array to include a reference electrode that is located at a maximum distance from the target nerve and senses the least amount of neural potential, allowing for accurate measurement of evoked neural responses to maintain therapeutic stimulus intensity and reduce energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the stimulus intensity is increased to maintain therapeutic effect, then neural recruitment is improved, but patient comfort deteriorates due to over-recruitment of Aβ fibres causing uncomfortable sensations
Solution Approach 1:
The patent employs a feedback control system that continuously monitors the evoked compound action potential (ECAP) amplitude and adjusts stimulus intensity accordingly. The system maintains the ECAP amplitude within a target range, automatically reducing intensity when it exceeds the upper threshold (preventing over-recruitment and discomfort) and increasing it when below the lower threshold (maintaining therapeutic effect). This closed-loop control resolves the contradiction by dynamically balancing therapeutic efficacy and patient comfort based on real-time neural response measurement.
2Reliability
If the stimulus intensity is increased to compensate for electrode migration or postural changes, then neural recruitment is maintained, but energy consumption increases
Solution Approach 1:
The feedback control system continuously measures the ECAP amplitude and adjusts stimulus intensity to maintain consistent neural recruitment despite electrode migration or postural changes. When the system detects a decrease in ECAP amplitude (indicating reduced neural recruitment due to migration or posture change), it automatically increases stimulus intensity only to the extent needed to restore the ECAP to the target range. This prevents unnecessary energy consumption while maintaining reliable neural recruitment.
3Use of energy by moving object
If the stimulus intensity is decreased to reduce energy consumption, then energy efficiency is improved, but neural recruitment becomes insufficient for therapeutic effect
Solution Approach 1:
The feedback control system ensures that stimulus intensity is never reduced below the level required to maintain the ECAP amplitude within the target range. The system continuously monitors neural response and automatically increases intensity if the ECAP amplitude falls below the lower threshold, ensuring therapeutic effect is maintained. This prevents premature reduction of intensity that would compromise therapy while optimizing energy usage by avoiding excessive intensity application.
4Device complexity
If a fixed reference electrode configuration is used, then device complexity is reduced, but measurement precision deteriorates due to electrode migration and postural changes
Solution Approach 1:
The patent implements a dynamic reference electrode selection system that automatically identifies and switches between different reference electrodes based on real-time measurement quality assessment. The system evaluates the stability and quality of the differential signal formed by each possible reference electrode configuration and dynamically selects the optimal combination. This resolves the contradiction by maintaining measurement precision through adaptive reconfiguration without requiring complex manual setup or multiple fixed configurations.
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 ensures consistent and comfortable neural stimulation by accurately measuring evoked neural potentials, adjusting stimulus intensity, and minimizing energy expenditure, thereby enhancing the therapeutic efficacy and patient comfort.
Implementation Method 1
a measurement electrode to detect an evoked neural potential generated by the neural fibres
Implementation Method 2
An electrical pulse of sufficient intensity applied to the target neural fibres by a stimulus electrode causes the depolarisation of neurons in the fibres, which in turn generates an action potential in the fibres
Data Source
AI summary
Disclosed is a method and system for selecting a reference electrode wherein at least one electrode of an electrode assembly is configured in a sensing mode and is connected to a sensing circuitry configured to measure a neural potential. Further, the electrodes configured in the sensing mode includes at least one measuring electrode and at least one reference electrode. The method and system can configure the electrodes of the electrode assembly based on conditions related to the stimulation and neural measurement.