FIGURE 2.

Schematic overview of the generator and amplifier setup used for unipolar and bipolar electroporation. The scheme in the upper half demonstrates a true DC high-voltage amplifier used for unipolar electroporation (FB signifies feedback circuit). This amplifier can in principle be used for bipolar electroporation, but to minimize the DC component, we developed an amplifier with a transformer output, depicted in the lower half. The inset illustrates the first two periods of the bipolar output of the transformer-based amplifier; the peak amplitude was 50 V (100 V total swing), and the scale bar delineates 10 μs. Pulse flanks had an exponential time course characterized by a time constant of 1.75 μs on average for the unipolar amplifier and 2.86 μs for the bipolar amplifier.