Quadrupoles for Remote Electrostimulation Incorporating Bipolar Cancellation.

A method that utilizes nanosecond bipolar cancellation (BPC) near a quadrupole electrodes to suppress a biological response but cancels the distal BPC at the quadrupole center, i.e., cancellation of cancellation (CANCAN), may allow for a remote focused stimulation at the quadrupole center. The primary object of this study was to outline the requirement of the CANCAN implementation and select an effective quadrupole configuration. We have studied three quadrupole electrode configurations, a rod quadrupole, a plate quadrupole (Plate-Q), and a resistor quadrupole. The pulse shapes of electric fields include monophasic pulses, cancellation pulses, and additive pulses. The Plate-Q appears the best for CANCAN as it shows the highest percentage of cancellation pulses among all pulse shapes, allowing for the best spatial focus. For the region of interest characterized in the Plate-Q configuration, the maximum magnitude of bipolar field is twice as that of the unipolar field, which allows for the CANCAN demonstration that involves membrane electropermeabilization.