In vivo studies of tumor-cell apoptosis induced by nanosecond pulsed electric field require high-voltage nanosecond pulses delivered to the biological tissues. In this paper, a newly developed all-solid-state nanosecond pulse generator based on the Marx generator concept is proposed for this application. The generator comprises four parts: a dc charging power, a solid-state Marx circuit using metal-oxide-semiconductor field-effect transistors, a control circuit using a field-programmable gate array, and the load. This generator has the capability of producing repetitive pulses with a voltage up to 8 kV, pulsewidth of 200-1000 ns, rise time of 35 ns, and repetition rate of 1-1000 Hz with various resistive loads and 1-kV dc input voltage. The all-solid-state design makes the generator compact and reliable. Initial experiments were carried out to verify the performances of the proposed generator.

FPGA-Controlled All-Solid-State Nanosecond Pulse Generator for Biological Applications

Using simple but powerful electronics concepts, such as a mass produced Schmitt trigger and integrated MOSFET driver in novel circuit applications, a simple 400-V 75-ns pulse generator (pulser) has been designed, developed, and tested. For a 50-/spl Omega/ matched load, the pulser produces extremely well-defined, repetitive high-voltage pulses that are free from overshoot and ringing. The width of the pulses is adjustable from 75 ns to 10 ms with the fall times of a few tens of nanoseconds for a negative wave and a repetition period of 1.5 /spl mu/s with the existing setup. By upgrading to a more complex driver circuit, much lower pulsewidths are possible. Using a 1-4 mm standard commercial cuvette, it is possible to generate electric fields of 4-1 kV/cm with this pulser. The purpose is to try to do electroporation mediated gene therapy on mammalian cells at higher electrical field strengths and submicrosecond or microsecond pulsewidths compared to conventional 200 V/cm and tens of millisecond-duration pulsewidths.

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Simple MOSFET-based high-voltage nanosecond pulse circuit

The Graphical User Interface (GUI) of the biomedic al equipment is expected to perform reliably and to assure fast response at a maximum level of safety. We designed a user-friendly GUI to control the high -voltage signal generator (electroporator). Electroporation is a phenomenon in which biological cell membrane permeability becomes transiently increased due to exposure to an electric field caused by high-voltage electric pul ses. Electroporation is used in electrochemotherapy, gen e electrotransfer and non-thermal tissue ablation. A custom- developed high-voltage signal generator (electropor ator) was designed as a modular solution embedding a Mini- ITX platform with the Microsoft Windows CE 5.0 operating system. A custom application was designed in V isual Basic .NET to control the output power stage via a U niversal Serial Bus 2.0 connection. The device is co mpact and controlled using a touch-screen display. Due to the shellless operating system the user does not feel to be using a Personal Computer at all. Namely, the GUI layout is designed intuitively needing no knowledge of the de vice properties or electronics.

A Graphical User-interface Controller for the Biomedical High-voltage Signal Generator

The present invention relates to means and devices for generating an electromagnetic propulsion force, and more particularly but not exclusively an electromagnetic force acting over the time delay τ necessary to a primary field to reach and interact with a secondary circuit, and vice-versa, in conformity with Einstein's Relativity Principles, wherefrom the Newton's Third Law would not apply during τ, thus leading to an asymmetric system of forces that would permit the advantageous exploitation of the preponderant force.

Relativistic ponderomotive force generator

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Research and development of the high-frequency square-wave pulse electroporation system

Nanosecond pulse generators, which provide kilovolt pulses, are required for applications such as pulsed lasers, electro-optical devices, electron heating of plasmas, and bioelectrics. Switches used to generate such short pulses include high-pressure spark gaps, photoconductive switches and semiconductor opening switches. Most of the pulse generators based on these switch technologies are designed for high voltage, high power applications. We have explored two concepts that of a MOSFET triggered, microspark Marx-Bank and a combined microspark-semiconductor switch system as a means to generate simple, inexpensive nanosecond pulse generators. The compact pulse generators allow us to generate electrical pulses of less than 10 ns duration, with amplitudes of several kV. The Mini Marx Bank has been shown to provide 6 kV pulses of 6 ns duration into a 10 M/spl Omega/ load and 2 kV into a 50 /spl Omega/ load. The second switch system, which utilizes a microspark switch and a commercially available diode to shorten the pulse, has provided 2.6 kV pulses of 2 ns duration into a 50 /spl Omega/ load. The low cost of the generator components, and the compact size make these devices easy to built and convenient to use in nanosecond pulsed power experiments.

M. Herrmann

Papers

Nanosecond, kilovolt pulse generators