Four-channel pulse generator for real-time biological investigations

New advances in pulse generators for real-time fluorescence microscopy of cell electroperturbation are presented. A MicroPulser described here is constructed as part of a fluorescence imaging system to expose four independent samples on a single microscope slide to nanosecond pulsed electric fields. The all solid-state pulse generator is a totem pole design delivering 450 V pulses with 0.5-ohm source impedance. The pulse generator, voltage monitor, current monitor, four-channel selection circuit, and housekeeping are contained on a 2.5 inchtimes3.8 inch printed circuit board (PC board). Temporal features of a TTL level trigger input are replicated by the variable 0 to 450 V output pulse. Pulse width can range from 11 ns to DC with rise and fall times of about 3 ns. The pulse generator and interchangeable microscope slide reside on a customized stage insert plate for the fluorescence microscope. Optical and electrical interface to the sample on stage are made simultaneously. We describe here the design of the MicroPulser system, the pulse generator electronics, and electrode chamber for cells