Study of the dependency of the specific power absorption rate on several characteristics of the excitation magnetic signal when irradiating a SPION-containing ferrofluid

Abstract

[EN] Magnetic hyperthermia mediated by superparamagnetic particles is mainly based in sinusoidal waveforms as excitation signals. Temperature changes are conventionally explained by rotation of the particles in the surrounding medium. This is a hypothesis quite questionable since habitual experimental setups only produce changes in the magnetic module, not in the field lines trajectories. Theoretical results were tested by changing the waveform of the exciting signal in order to compare non-sinusoidal signals against sinusoidal signals. Experiments were done at different frequencies: 200 KHz, 400 KHz, 600 KHz, 800 KHz and 1 MHz. Super paramagnetic Iron Oxide samples (SPION), made of magnetite (Fe3O4) and suspended in water (100 mg/ml), were used. Magnetic field strength varies from 0.1 +/- 0.015 KA/m to 0.6 +/- 0.015 KA/m. In this study was observed that the power loss depends on the applied frequency: for 1 to 2.5 RMS current the responses for each signal are part of the higher section of the exponential function, and for 3.5 to 8 RMS current the response is clearly the decrement exponential function's tale (under 1 x 10(3) LER/gr).