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Design of Monophasic Spike-Exponential Waveform for Functional Electrical Stimulator Based on Pulse Width Modulation
A. P. Hutomo, I. P. Buditomo, A. P. Putra, S. Suhariningsih, S. D. Astuti,
Volume 15, Issue 4 (12-2019)
Abstract
The Functional Electrical Stimulator design using monophasic spike-exponential waveform was proposed and described in this study. The monophasic square waveform has benefit in generating an action potential, but it could cause side effects such as toxic caused by the electrode polarization. The square waveform signal which the frequency and pulse width could be modulated was manipulated to be the monophasic spike-exponential waveform. Transformer OT240 was applied at the end of the FES system part and functioned as a voltage amplifier and DC signal isolator. On every frequency range between 5–100 Hz, the 16 peak voltage stages with the lower limit of 45 Volt and an upper limit of 400 Volt was arranged to obtain VRMS value in each stage. Characterization result shows that the produced waveform was monophasic spike-exponential with the narrow pulse width (t1/2 = 7 µs) and VRMS in the maximum frequency and peak voltage was 8.99 Volt. This study showed that the designed FES had high VP and low VRMS, thus, it could be concluded that this FES system design could be a candidate for its application.

Flexible Pulsed Power Generator to Create Wide Range of Pulses for Cancer Treatment
A. Aziznia, M. S. Akhavan Hejazi,
Volume 19, Issue 1 (3-2023)
Abstract
In this paper, a flexible pulsed power generator (FPPG) based on the solid-state Marx Structure is designed to create a wide range of pulses for cancer treatment. Pulse with different characteristics is needed to treat different samples depending on their type, dimensions, and impedance. Also, with the change in pulse widths, the pulse characteristics suitable for treatment change widely. With conventional semiconductor base Marx generators, due to the limitations in their rise time, current level, and impedance characteristics, it is not possible to generate a wide range of pulse characteristics, especially for low impedance loads. The FPPG by changing the connection mode of two Marx generators, can decrease the generator impedance for low impedance loads, increase the output current and voltage amplitude and repetition rate, and generate pulse width from nanosecond to several hundred microseconds. The simulation of FPPG in OrCAD-PSpice software shows its proper functioning.

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© 2022 by the authors. Licensee IUST, Tehran, Iran. This is an open access journal distributed under the terms and conditions of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) license.