Pulsed Power Generators and Delivery Devices for Bioelectrical Applications

Bioelectrics, or the application of ultrashort electric fields to biological cells and tissue, has gained considerable interest over the last several years. In particular, pulses with pulse-widths of less than the charging time of the outer membrane of cells offer new insights and applications, For mammalian cells, this charging time is on the order of 100 ns. In this time-range, the electric field can penetrate into the cell and can potentially trigger effects such as permeabilization of intracellular organelles, release of Ca2+, control of apoptosis (controlled cell-death), enhancement of gene transfection efficiency, shrinkage and complete elimination of melanoma tumors, and changes in plasma membrane voltage. This paper will discuss several of the nanosecond pulse generators in use at the Center for Bioelectrics to conduct the research mentioned above. They range from low-voltage pulsers for microscopes, to high-voltage pulsers for cuvettes and tissue, and are used to generate the necessary 10-300 kV/cm electric fields to trigger aforementioned effects. The technologies used for pulse generation range from pulse forming networks (PFNs) in various configurations to pulse forming lines (PFLs) using strip-lines or coaxial transmission lines. Typical pulsewidths are 10, 60, 100, and 300 ns, with voltages between 1-40 kV, and rise-times of 2-30 ns. This paper will also include the delivery systems used to expose cell suspensions and tissue to electrical pulses. They include cuvettes (10 Omega) for the exposure of cell suspensions, microreactors (100 Omega) for single cells, and dual-needles (kOmegas) for tissue samples