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Home page > LPCNO > Seminars > 2013 > Mechanisms of heating characteristics in magnetic nanoparticle suspensions over a wide range of frequencies and amplitudes of an alternating magnetic field

Mechanisms of heating characteristics in magnetic nanoparticle suspensions over a wide range of frequencies and amplitudes of an alternating magnetic field

Date : 27/06/2013 à 15:00

Titre : Mechanisms of heating characteristics in magnetic nanoparticle suspensions over a wide range of frequencies and amplitudes of an alternating magnetic fields

Intervenant : Eiji Kita

Provenance : Institute of Applied Physics, University of Tsukuba, Japan

Salle : Salle de séminaire

Résumé: Application of nanomagnets in the biomedical field, especially for cancer therapy, has attracted attention. For use in cancer therapy, the magnetic nanoparticles require strong heating power. In general, high frequencies and amplitudes of an alternating magnetic field (AMF) give rise to high heat generation. However, there is a limitation on the use of magnetic fields as the AMF has considerable influence on living organisms, for example heat up due to eddy currents. Therefore, effective use of the AMF must be considered. There are three major contributors to heat generation by magnetic nanoparticles: ferromagnetic hysteresis, superparamagnetic (SPM) relaxation (Neel relaxation), and Brownian relaxation. To understand and differentiate between these heating mechanisms, the heating characteristics of a suspension of magnetic nanoparticles were investigated over a wide range of frequencies and amplitudes of an AFM, because the response of the nanoparticles depends on the mechanism. A high magnetic field generator (up to 400 - 500 Oe) with a wide frequency range (100 kHz–800 MHz) was built, and the mechanism of heat generation in a few different sorts of water-based nanoparticle suspension was examined experimentally. Each suspension depicted a characteristic heating property depending on the magnetic nanoparticle such as ferromagnetic nano-platelets (DINP) or SPM particles. The optimum condition under limited amplitudes of magnetic field and frequency will be discussed.