Nanosecond-Duration Electric Pulse Delivery In Vitro and In Vivo: Experimental Considerations

Microsecond-duration electric pulses are widely used for research and therapeutic purposes. The most commonly used device for in vitro exposure to electric pulses is a standard electroporation cuvette. The use of nanosecond-duration electric pulses [nanosecond pulsed electromagnetic fields (nsPEFs) or nanopulses] is an emerging technology. For microsecond pulses, some dedicated generators with voltage regulation have been developed and allow one to easily impose a well-known voltage during biological experiments. However, it is not the case for nsPEF. The application of nsPEF thus requires considering the output impedance of the generator used and the impedance of the biological load because both impose the magnitude and the shape of the applied pulses. The model proposed here describes the behavior of the biological sample on a large frequency band (100 Hz to 3 GHz), including or not the exposure device. This model allows predicting the real electric pulses applied to biological samples and highlights the limitations induced by the use of standard electroporation cuvettes. Considering this kind of application device and the use of 10-ns-duration trapezoidal electric pulses, we evaluate the distortion of the pulses and also the impact of the output impedance of the generator on the steepness of the pulse rising and falling edges. This study is then transposed to potato tuber, a model currently used as a homogeneous biological tissue.