Remote Current Sensing Using Reflectometry for Bioelectric Applications

Monitoring impulse current is of great importance for pulsed power applications in medicine, where the in situ power monitoring is needed to ensure the right dosage delivery based on the treatment outcome. However, the direct current measurement at the treatment site is not practical, especially in a clinical setting. In addition, the transmission line and electrodes used in applications make currents measured at different locations of the system significantly different due to the propagation effect, especially for ultrashort pulses, e.g., tens of nanoseconds pulses. Using a photoconductive semiconductor switch (PCSS)-based generator, a remote current sensing method is demonstrated here. This voltage reflectometry-based method was validated over a range of resistive loads and a complex load that was simulated by a helium nanosecond-pulsed atmospheric-pressure plasma jet (ns-APPJ) system. The ns-APPJ was generated in ambient air with a pin-to-plate electrode configuration that was powered by 20-ns, 15-kV pulses, provided by the same PCSS-switched pulse generator. In addition, a short, open, load (SOL)-based calibration procedure to determine the conduction component out of the total current flowing through the ns-APPJ system was presented. Finally, the use of voltage reflectometry to determine the successful delivery of a voltage pulse to the load was discussed.