Fractionalized Monophasic Sub-Pulse Waveforms for SCS
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Solution Overview
Problem
Current Spinal Cord Stimulation (SCS) systems face challenges with high-frequency pulses, which increase power consumption and battery depletion, and can cause paresthesia; traditional low-frequency pulses may not effectively reduce paresthesia while requiring significant interphase periods and passive charge recovery.
Innovation Solution
The implementation of stimulation waveforms with fractionalized monophasic sub-pulses at both low and high frequencies, allowing for reduced switching in the stimulation circuitry and maintaining charge balance, thereby reducing power consumption and accommodating interphase periods for efficient charge recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If high-frequency pulses are used for stimulation, then paresthesia is reduced, but power consumption increases and battery life decreases
Solution Approach 1:
The pulse train is segmented into multiple phase pulses within each phase, where each phase contains a series of monophasic sub-phase pulses. This segmentation allows the system to achieve high-frequency stimulation effects while maintaining charge balance and reducing overall power consumption by distributing the stimulation across multiple smaller pulses rather than using continuous high-power pulses.
2Use of energy by moving object
If traditional low-frequency pulses are used, then power consumption is reduced, but paresthesia cannot be effectively reduced and interphase periods are required
Solution Approach 1:
The system changes the frequency parameter dynamically by delivering monophasic sub-phase pulses at a high frequency (e.g., 2500 Hz) within each phase, while maintaining a lower overall pulse repetition rate. This parameter change allows the system to achieve paresthesia-free stimulation at high frequencies without the continuous power consumption of traditional high-frequency stimulation, as charge recovery occurs during the interphase periods.
3Object-affected harmful factors
If high-frequency stimulation is applied, then paresthesia-free therapy is achieved, but switching activity in circuitry increases
Solution Approach 1:
The stimulation follows a periodic pattern with phases and interphase periods. Each phase delivers a train of monophasic sub-phase pulses at high frequency, followed by an interphase period where no stimulation occurs, allowing charge recovery. This periodic action reduces the average switching activity compared to continuous high-frequency stimulation, as switches remain inactive during interphase periods.
4Duration of action of stationary object
If charge balance is maintained with traditional waveforms, then battery life is extended, but interphase periods are required which reduce stimulation efficiency
Solution Approach 1:
Each phase is segmented into multiple monophasic sub-phase pulses, allowing charge balance to be achieved within each phase rather than requiring long interphase periods between phases. This segmentation enables more efficient use of the interphase period, reducing the overall duration of stimulation interruptions while maintaining charge balance and extending battery life.
Data Source
AI summary
Waveforms for a stimulator device, and methods and circuitry for generating them, are disclosed having high- and low-frequency aspects. The waveforms comprise a sequence of pulses issued at a low frequency which each pulse comprising first and second charge-balanced phases. One or both of the phases comprises a plurality a monophasic sub-phase pulses issued at a high frequency in which the sub-phase pulses are separated by gaps. The current during the gaps in a phase can be zero, or can comprise a non-zero current of the same polarity as the sub-phase pulses issued during that phase. The disclosed waveforms provide benefits of high frequency stimulation such as the promotion of paresthesia free, sub-threshold stimulation, but without drawbacks inherent in using high-frequency biphasic pulses.