A high-frequency AC generator with high gain powered by a 3.7 V battery for tumor treating fields

Abstract High-frequency AC field (100–300 kHz), which could generate tumor treating fields (TTFields) has been FDA-approved for glioblastoma multiforme treatment. TTFields generator design with battery power is important for outdoor treatment. In general, the LCLC step-up resonant circuit is a viable filter option to improve the voltage of the AC waveform. In this study, we utilized the LCLC circuit with a linear isolated transformer to boost the voltage of the AC waveform with 200 kHz powered by batteries. Our theoretical analysis indicates that compared with the LCLC circuit, the resonant frequency changeis relatively narrow with a large range of excitation inductance of the transformer, thus benefiting from selecting the excitation inductance parameter to shift the targeted frequency to the resonant frequency, and then achieving a high voltage gain with low input power. The designed prototype can output a 66.0 V waveform at 200 kHz powered by a 3.7 V DC battery, where the voltage gain reaches 17.8. The excitation inductance of the transformer was properly selected to achieve a similar output voltage for capacitive bio-loading of the output waveform within 8.7 h with a low input power of 5.1 W and four 18650 lithium batteries (3200 mAh). The insulated electrode was designed for in vitro U251 cell proliferation experiments. The results showed that the cell viability could decrease to 70.2 ± 4.5%, compared with the control group, which indicates that the designed generator could inhibit cell proliferation significantly. This paper may provide a proper design method o AC generators for TTFields treatment.