Hybrid Waveform Nerve Fiber Conduction Block
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Solution Overview
Problem
Current neural stimulation devices for treating diseases using kilohertz frequency (KHF) waveforms struggle with selective nerve fiber conduction block due to poor understanding of waveform parameters and non-monotonic frequency effects, which limits their ability to target specific nerve fibers effectively.
Innovation Solution
A hybrid waveform comprising a kilohertz frequency (KHF) component and a direct current (DC) component is applied to achieve selective and unidirectional nerve fiber conduction block, with the KHF component being biphasic and the DC component having unequal phase durations or amplitudes, creating a net charge imbalance to control block thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If KHF waveforms are used to block nerve fiber conduction, then conduction block is achieved, but selective targeting of specific nerve fibers is limited due to poor understanding of waveform parameters and non-monotonic frequency effects
Solution Approach 1:
The patent systematically varies waveform parameters including frequency (1-200 kHz), amplitude, pulse width, and duty cycle to identify optimal settings for selective nerve fiber block. By changing these parameters, the invention achieves frequency-dependent selectivity where specific fiber types (A-alpha, A-beta, A-delta, C fibers) can be targeted based on their diameter and conduction velocity characteristics
Solution Approach 2:
The patent employs asymmetric biphasic waveforms with unequal cathodal and anodal phases. The cathodal phase (first phase) has different amplitude and duration characteristics compared to the anodal phase (second phase), creating a net charge transfer that enhances selective block of smaller diameter fibers while preserving larger fiber conduction. This asymmetry is key to achieving the non-monotonic frequency effects that enable fiber-type selectivity
2Manufacturing precision
If higher signal frequencies are used to block slower conducting fibers, then fiber-type selective block is achieved, but block thresholds increase due to passive membrane property attenuation
Solution Approach 1:
The patent utilizes the dynamic interaction between frequency-dependent passive membrane attenuation and active sodium channel kinetics. By operating at specific frequencies where the attenuation characteristics create non-monotonic threshold relationships, the invention achieves selective block of slower conducting fibers at lower thresholds. The dynamic balance between capacitive coupling effects and ionic channel behavior enables this frequency-dependent selectivity
Solution Approach 2:
The patent replicates and validates findings from computational modeling studies through in vivo experiments. The computational models predicted non-monotonic block thresholds with specific frequency dependencies, and the patent confirms these predictions experimentally, establishing a reliable framework for frequency-selective nerve block that can be applied across different nerve types and species
3Manufacturing precision
If charge-imbalanced asymmetric waveforms are used to achieve non-monotonic block thresholds, then fiber-selective block is enabled, but potential nerve damage from direct current may limit long-term use
Solution Approach 1:
The patent applies small, controlled amounts of charge imbalance rather than large DC components. By using partial charge imbalance (unequal but not extreme differences between cathodal and anodal phases), the invention achieves the necessary non-monotonic threshold effects for fiber selectivity while keeping the net DC charge transfer below levels that would cause electrochemical damage or tissue heating. This partial action approach maintains therapeutic effectiveness without exceeding safety thresholds
Solution Approach 2:
The patent employs periodic biphasic waveforms where the charge imbalance is reset with each cycle. The alternating cathodal-anodal phases ensure that any net charge transfer is periodically reversed, preventing cumulative DC effects that would lead to nerve damage. This periodic structure allows sustained long-term use by continuously neutralizing potential harmful charge accumulation while maintaining the selective block effect during the active phases
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
The hybrid waveform enables precise control over nerve fiber conduction block, allowing for selective targeting of smaller or larger diameter nerve fibers and achieving unidirectional block, thereby improving the efficacy of neural modulation treatments.
Implementation Method 1
KHF signals produce persistent mean depolarization of the axonal membrane near the electrode contacts, causing sodium channel inactivation and local conduction block
Implementation Method 2
the net charge imbalance is obtained by: (a) adjusting the amplitude of the DC offset superimposed on the KHF component; (b) adjusting the magnitude of the difference in the phase durations of the KHF component
Data Source
AI summary
The present disclosure provides systems and methods relating to neuromodulation. In particular, the present disclosure provides systems and methods for selective and/or unidirectional nerve fiber conduction block though the application of a hybrid waveform using a neuromodulation device. The systems and methods of neuromodulation disclosed herein facilitate the treatment of various diseases associated with pathological neural activity.