A frequency-adjustable electromagnet for hyperthermia measurements on magnetic nanoparticles

TL;DR

This paper presents a low-cost, highly efficient electromagnet setup with adjustable frequency for hyperthermia measurements on magnetic nanoparticles, enabling precise assessment of heating properties in colloidal solutions.

Contribution

The paper introduces a novel, optimized electromagnet setup with adjustable frequency for hyperthermia measurements, improving efficiency and sensitivity over previous methods.

Findings

Achieved magnetic fields up to 30 mT at 100 kHz.

Demonstrated measurement of weak heating powers in diluted solutions.

Measured frequency-dependent hyperthermia characteristics of Fe nanoparticle solutions.

Abstract

We describe a low-cost and simple setup for hyperthermia measurements on colloidal solutions of magnetic nanoparticles (ferrofluids) with a frequency-adjustable magnetic field in the range 5-500 kHz produced by an electromagnet. By optimizing the general conception and each component (nature of the wires, design of the electromagnet), a highly efficient setup is obtained. For instance, in a useful gap of 1.1 cm, a magnetic field of 4.8 mT is generated at 100 kHz and 500 kHz with an output power of 3.4 W and 75 W, respectively. A maximum magnetic field of 30 mT is obtained at 100 kHz. The temperature of the colloidal solution is measured using optical fiber sensors. To remove contributions due to heating of the electromagnet, a differential measurement is used. In this configuration the sensitivity is better than 1.5 mW at 100 kHz and 19.3 mT. This setup allows one to measure weak heating powers on highly diluted colloidal solutions. The hyperthermia characteristics of a solution of Fe nanoparticles are described, where both the magnetic field and the frequency dependence of heating power have been measured.