Broadband Power Measurement of High-Voltage, Nanosecond Electric Pulses for Biomedical Applications

Experimental studies have shown that nanoelectropulses of sufficiently short rise time and duration can trigger cell apoptosis (programmed cell death). Specifically, pulses that last less than 20 ns have been shown to kill a wide variety of human cancer cells in vitro as well as induce tumor regression in vivo. To better understand the mechanisms by which nanopulses affect cancer cells, the electrical characteristics of the cells should be characterized so that it is clear how electrical energy is delivered. To achieve this end, a power measurement device that integrates into a nanopulse transmission line used for in vivo experiments has been designed, built, and calibrated. The device provides voltage and current measurements without disturbing the transmission of the pulse to the biological sample. The in vivo sample can be characterized either by a direct voltage/current measurement or by measuring the incident and reflected voltage pulse and using time domain reflectometry to calculate the impedance. The 3 dB bandwidth of both the microstrip line and the voltage attenuator has been measured to be 900 MHz and 1.25 GHz respectively.