Neural Sensing Artifact Reduction via Charge Balancing
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Solution Overview
Problem
Existing neurostimulation techniques, such as spinal cord stimulation, face challenges in efficiently sensing evoked compound action potentials (ECAPs) due to stimulation artifacts (SAs) that are orders of magnitude larger, obscuring the evoked response and requiring high input dynamic range and computing-intensive signal processing.
Innovation Solution
A device and method that adjust the charge balancing pulse amplitude and width in biphasic electrical stimulation phases to minimize residual charge in tissue, changing the SA slope and amplitude until it is below a threshold, allowing for efficient ECAP sensing by reducing the active balancing phase charge and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard active charge balancing with matched charge is used, then charge balancing is achieved, but stimulation artifact remains large obscuring ECAP sensing
Solution Approach 1:
The patent changes the parameters of the charge balancing pulse, specifically reducing its amplitude and/or pulse width below the level required for complete charge balancing. This partial charge balancing approach reduces the stimulation artifact while maintaining sufficient charge balance to enable ECAP sensing, resolving the contradiction between achieving charge balance and minimizing artifact.
2Object-affected harmful factors
If charge balancing pulse amplitude and width are reduced, then stimulation artifact is minimized, but charge balancing completeness may be compromised
Solution Approach 1:
The patent employs feedback by measuring the stimulation artifact and using this information to adjust the charge balancing pulse parameters. The system iteratively reduces the charge balancing pulse amplitude and/or pulse width while monitoring the artifact level, stopping when the artifact reaches a minimum threshold, thus achieving optimal partial charge balancing that maintains reliability while minimizing artifact.
3Measurement precision
If ECAP sensing is performed with large stimulation artifact, then sensing can be performed, but high input dynamic range and computing-intensive processing are required
Solution Approach 1:
The patent applies preliminary action by reducing the stimulation artifact through adjusted charge balancing before ECAP sensing begins. By minimizing the artifact in advance through optimized charge balancing pulse parameters, the system simplifies subsequent signal processing requirements and reduces the input dynamic range needed for ECAP detection, avoiding the need for complex post-processing.
4Reliability
If conventional charge balancing is used, then charge balance is maintained, but power consumption is higher due to larger balancing pulse
Solution Approach 1:
The patent reduces power consumption by changing the parameters of the charge balancing pulse, specifically reducing its amplitude and/or pulse width. This partial charge balancing approach delivers sufficient charge balance for ECAP sensing while consuming less energy than conventional complete charge balancing, resolving the contradiction between maintaining charge balance reliability and reducing power consumption.
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 effectively minimizes stimulation artifacts, reducing power consumption and enhancing the clarity of ECAP sensing, particularly in closed-loop spinal cord stimulation systems, by adjusting the charge balancing pulse to match the final biphasic stimulation phase, enabling more efficient and accurate sensing of neural activity.
Implementation Method 1
a pulse generator configured to deliver a plurality of successive biphasic electrical stimulation phases
Implementation Method 2
each comprising a stimulation pulse, a successive interphase period, and a successive charge balancing pulse
Data Source
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AI summary
The present invention relates to a device for neurostimulation, comprising: a pulse generator (100) configured to deliver a plurality of successive biphasic electrical stimulation phases (103), each comprising a stimulation pulse (103.a), an interphase period (103.b), and a charge balancing pulse (103.c), each pulse comprising an amplitude and a pulse width, at least a first electrode and a second electrode (102.a, 102.b) for delivering electrical biphasic stimulation phases (103), and wherein the device is configured to determine the slope and/or an absolute amplitude of a stimulation artifact generated by the respective biphasic electrical stimulation phase (103), wherein the device is further configured to reduce the amplitude and/or pulse width of the charge balancing pulse (103.c) of each biphasic electrical stimulation phase (103) with respect to the preceding biphasic electrical stimulation phase (103) until a final electrical stimulation phase (103) with reduced amplitude and/or pulse width of the charge balancing pulse (103.c) generates a stimulation artifact whose slope changed sign and/or having an absolute amplitude below a threshold, and wherein the device is configured to deliver therapy in form of at least one electrical biphasic stimulation phase having a charge balancing pulse comprising the amplitude and/or pulse width of the charge balancing pulse (103.c) of said final biphasic electrical stimulation phase (103), and wherein the device is configured to measure an evoked compound action potential (300) triggered by the delivered therapy.