Resonant Pulse Generator for Accurate Defibrillation Waveforms
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Solution Overview
Problem
Existing electrotherapy systems for treating cardiac arrhythmias, such as ventricular fibrillation, face challenges in efficiently delivering electrotherapeutic pulses without requiring electrical isolation and transformers, while maintaining waveform accuracy and energy efficiency.
Innovation Solution
A system utilizing a resonant therapeutic current control network with a controller that switches between parallel and series configurations based on patient impedance and voltage, enhancing voltage boosting and reducing common-mode noise, and employing a bidirectional charging control network for energy management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional electrical stimulators use simple waveforms (square waves, sine waves, or exponential decay monophasic pulses), then the device complexity is low and ease of manufacture is high, but the ability to selectively activate nerve fibers based on diameter or myelination is insufficient
Solution Approach 1:
The patent applies periodic action by using biphasic pulses with specific timing characteristics. The first phase activates nerve fibers while the second phase reverses the potential, creating a periodic waveform that selectively activates targeted fibers. The pulse duration (e.g., 200 microseconds total with 100 microsecond phases) and interphase interval are carefully controlled to achieve selective activation without requiring complex device architecture.
2Adaptability or versatility
If high amplitude monophasic pulses are used to achieve selective activation, then the nerve fiber selectivity improves, but the risk of tissue damage and discomfort increases
Solution Approach 1:
The patent converts the potentially harmful effect of high amplitude monophasic pulses into a beneficial biphasic waveform. The first phase delivers the activating stimulus, while the second phase (reverse polarity) serves to deactivate and protect tissue by reversing the potential. This transforms what would be a harmful sustained depolarization into a protective cyclic process, reducing tissue damage and discomfort while maintaining selectivity.
Solution Approach 2:
By using periodic biphasic pulses with controlled duration and amplitude, the system achieves selective activation without sustained high amplitude exposure. The alternating phases distribute the electrical stress over time, preventing the cumulative tissue damage associated with continuous monophasic high amplitude pulses.
3Adaptability or versatility
If complex waveforms are used to achieve selective activation, then the adaptability improves, but the ease of operation and programming becomes more difficult
Solution Approach 1:
The patent achieves selective activation through controlled parameter changes in the biphasic waveform - specifically pulse duration (e.g., 200 microseconds), phase amplitude (e.g., 1.5 times cathodal for anodal pulses), and interphase interval. These parameters can be adjusted to target different fiber types while maintaining a relatively simple waveform structure that is easier to program and operate compared to more complex waveforms.
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 system achieves efficient delivery of electrotherapeutic pulses with high energy efficiency and accuracy, minimizing waveform deviations and energy loss, suitable for use in defibrillation and pacing applications.
Implementation Method 1
electrical stimulation has been used to treat a variety of medical conditions
Implementation Method 2
excitation of a nerve fiber occurs when the transmembrane potential of the nerve fiber is depolarized to a threshold level, thereby triggering an action potential
Implementation Method 3
a capacitor may be charged during a first time period and discharged during a second time period to generate a first phase of a plurality of phases of the pulse waveform
Implementation Method 4
an inductor may be discharged during the first time period to generate the first phase of the pulse waveform
Data Source
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Figure 2A
AI summary
Electrotherapy waveform and pulse generation and delivery systems, methods and devices are described, such as for generation and delivery of defibrillation or pacing electrotherapeutic waveforms to patients, using open or closed loop current control. An example system includes a power supply, a therapeutic current control network including a resonant tank and at least one current control switch, and a controller. The controller may adjust operation of at least one current control switch in adjusting delivery of an electrotherapeutic waveform to the patient to correspond with a specified waveform. Therapeutic current control networks are described that are quasi-resonant and boost a voltage of an electrotherapeutic waveform delivered to the patient. Therapeutic current control networks are also described that may switch between a parallel resonance mode and a series resonance mode. Systems are described that may utilize one or more of soft switching, wide bandgap materials and a bidirectional power supply.