A high-resolution frequency variable experimental setup for studying ferrofluids used in magnetic hyperthermia

Abstract

A scanning system for specific absorption rate of ferrofluids with superparamagnetic nanoparticles is presented in this study. The system contains an induction heating device designed and built with a resonant inverter in order to generate magnetic field amplitudes up to 38 mT, over the frequency band 180-525 kHz. Its resonant circuit involves a variable capacitor with 1 nF of capacitance steps to easily select the desired frequency, reaching from 0.3 kHz/nF up to 5 kHz/nF of resolution. The device performance is characterized in order to compare with the theoretical predictions of frequency and amplitude, showing a good agreement with the resonant inverters theory. Additionally, the setup is tested using a synthetic iron oxide with 10 ± 1 nm diameter suspended in liquid glycerol, with concentrations at 1%. Meanwhile, the temperature rise is measured to determine the specific absorption rate and calculate the dissipated power density for each f. This device is a suitable alternative to studying ferrofluids and analyzes the dependence of the power absorption density with the magnetic field intensity and frequency.

A microscopic approach to heating rate of ferrofluid droplets by a magnetic field

“…The minimum and maximum values for the frequency have been determined by using the smallest and largest values of the energy spacing between the levels ofĤ S . These values are given by 2 , with h being the Planck constant.…”

“…whereŜ( j) is the spin operator acting on states defined in Eq. (2). In general, the operatorŜ( j) is written as a series of crystal field operators carrying the information about the geometry of the lattice.…”

“…In fact, one of these applications is the so-called magnetic hyperthermia (MH), where the ferrofluid is used to provide the heating of a system. [1][2][3][4][5][6][7][8][9][10][11] When an external magnetic field is applied, induced magnetization lags the external field which results in heat dissipation at the fluid. Ferrofluids can be of interest in the construction of combustion chambers, whose projected size increases with the time taken for heating, vaporization, and consequently, burning of the fuel droplets.…”

Nanopartículas de magnetita dopadas com zinco para fins teranósticos: magnetoacustografia e hipertermia magnética

“…Cano et al [196] reported on a system based on resonant inverter with a 25 turn three layers solenoid coil with inner diameter of 5 cm generating a single frequency (206 kHz) magnetic field of 12 kAm -1 . Mazon et al [197] to improve the system reported in Cano et al [196] constructed a frequency variable system composed by a resonant inverter to generate the magnetic field over the frequency band 180-525 kHz and field amplitude up to 30.2 kAm -1 . In another improvement, Mazon et al [198] added a phase lock loop (PLL) circuit to their system to accurately tune the resonant frequency of the system during the experiments according to the inductance and capacitance of the resonant tank.…”

“…magnetic hyperthermia, several different topologies using soft-switching technique have been proposed e.g. full-bridge [196], half-bridge [197], push-pull [204] etc. These topologies usually employ metal-oxide semiconductor field-effect transistor (MOSFET) device for switching.…”