Neuromodulation System Biphasic Waveform Charge Balance
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Solution Overview
Problem
Conventional neuromodulation devices face challenges in modulating pre-synaptic terminals without causing paresthesia and in maintaining a nonzero net charge in targeted tissue, which can lead to galvanic corrosion and impracticality for electrode-based devices.
Innovation Solution
A neuromodulation system that uses a bipolar waveform with fractionalized current distribution across electrodes to selectively modulate presynaptic terminals, achieving sub-perception therapy by minimizing activation of dorsal column fibers and maintaining a net-zero overall charge injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a net-polarized electrotherapy waveform with DC component is applied to modulate pre-synaptic terminals, then therapeutic effect is improved, but galvanic corrosion of electrodes occurs and patient safety is compromised
Solution Approach 1:
The patent employs periodic biphasic waveforms where the polarity is reversed in successive phases, creating a time-varying electric field that modulates pre-synaptic terminals while maintaining zero net DC component, thereby preventing galvanic corrosion while preserving therapeutic efficacy
Solution Approach 2:
The patent changes the temporal parameters of the electric field by using asymmetric biphasic waveforms with different phase durations and amplitudes, allowing net charge accumulation in target tissue during the first phase while compensating with opposite polarity in the second phase, thus achieving therapeutic modulation without sustained DC bias that would cause corrosion
2Object-affected harmful factors
If conventional multi-phasic waveforms with polarity reversal are used to prevent galvanic corrosion, then electrode safety is improved, but the ability to maintain nonzero net charge in targeted tissue is lost
Solution Approach 1:
The patent uses periodic biphasic waveforms with asymmetric phase characteristics, where the first phase delivers charge to the target tissue and the second phase provides polarity reversal for electrode protection, achieving both net charge maintenance in tissue and prevention of galvanic corrosion through time-varying operation
Solution Approach 2:
The patent creates local charge accumulation in the target tissue during the first phase of the biphasic waveform while the second phase redistributes the charge, effectively maintaining nonzero net charge in the targeted region while ensuring overall charge balance at the electrode-tissue interface to prevent corrosion
3Reliability
If high-frequency spinal cord stimulation is applied to achieve net DC component through rectification, then therapeutic effect is improved, but paresthesia and discomfort increase
Solution Approach 1:
The patent changes the frequency and temporal characteristics of the stimulation waveform, using lower frequencies with asymmetric biphasic structure that allows pre-synaptic terminal modulation through charge accumulation without the high-frequency rectification effect that causes paresthesia and discomfort
Data Source
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AI summary
Multi-phasic fields (2206) are to be produced at a neuromodulation site using electrodes. A first phase (2202) is to be directed at a target region in order to inject a first-polarity electrical charge into the target region and a second phase (2204) is to be directed at portions of the neuromodulation site other than the target region in order to inject a second-polarity electrical charge, opposite the first-polarity electrical charge, into those portions of the neuromodulation site to essentially neutralize the first-polarity charge injected at the neuromodulation site while maintaining at least a portion of the first-polarity charge at the target region. In some cases, each electrode used as an anode to produce the first phase is to be used as a cathode to produce the second phase and each electrode used as a cathode to produce the first phase is to be used as an anode to produce the second phase.