Joule heating influence on the vitality of fungi in pulsed magnetic fields during magnetic permeabilization Vitalij Novickij • Audrius Grainys • Jurgita S ˇ vedien _ e • Svetlana Markovskaja • Jurij Novickij Received: 22 October 2013 / Accepted: 27 February 2014 Ó Akade ´miai Kiado ´, Budapest, Hungary 2014 Abstract Generation of the pulsed magnetic fields that are 5–6 orders of magnitude higher than the geomagnetic field requires switching of high pulsed currents. As a result, the occurrence of the Joule heating in the inductors limits the possible biological applications of the pulsed magnetic fields. This work is focused on the investigation of the generated Joule heating inside the inductors of different shapes. The analysis of the Joule heating influence on the vitality of biological objects during magnetic permeabili- zation is presented. The biological objects that are used in the study are the pathogenic fungi Candida albicans and Trichophyton rubrum, which are the common cases for human infections. The finite element method analysis of the pulsed inductors and the experimental results with the selected pathogenic fungi are overviewed. The limitations of the magnetic permeabilization technique due to the generated Joule heating are identified. Keywords Magnetoporation  Heat dissipation  Coil  Cuvette  Thermal analysis Introduction Considerable amount of research in the area of how static and low frequency weak magnetic fields influence the vitality of the biological objects such as cells, fungi, bac- teria, or other microorganisms has been performed [1–4]. However, the area of high magnetic field application in biology still holds the position of one of the most contro- versial and poorly studied [5]. Such factors as the com- plexity of the repetitive pulsed magnetic field generators, the high amount of heat dissipated during high current flow, and the lack of standardization of the pulsed magnetic field experiments could be the major reasons [6]. Currently, the most convenient and preferred method for generation of the high pulsed magnetic field is the appli- cation of the solenoid type inductors, which ensures acceptable field homogeneity ( [ 90 %) across considerable volume of effect [7, 8]. In this case, a cylindrical cuvette for biological samples could be easily implemented inside the inductor allowing controlled and equal exposure of the samples to the pulsed magnetic field. Also, steep high magnetic field pulses are advantageous because higher induced electric field inside the biological samples could be achieved [9]. However, application of the high currents in the range of kA is required, which results in the generation of Joule heating in the solenoid [10, 11]. The thermal influence affects and distorts the biological experiments; therefore, Joule heating must be considered during repeti- tive pulsed magnetic field treatment. The common biological samples that are selected for magnetic field treatment are the pathogenic fungi [12]. The reason for this is the variety of human skin, nail, hair, and mucosa infections that the fungi are causing, such as tinea pedis, tinea cruris, tinea corporis, and candidal mycoses [13, 14]. Research of new antifungal techniques is V. Novickij (&)  A. Grainys  J. Novickij High Magnetic Field Laboratory, Vilnius Gediminas Technical University, Naugarduko 41, 03227 Vilnius, Lithuania e-mail: vitalij.novickij@gmail.com; vitalij.novickij@vgtu.lt J. S ˇ vedien _ e Laboratory of Biodeterioration Research, Institute of Botany of Nature Research Centre, Zaliuju ezeru g. 49, 08406 Vilnius, Lithuania S. Markovskaja Laboratory of Mycology, Institute of Botany of Nature Research Centre, Zaliuju ezeru g. 49, 08406 Vilnius, Lithuania 123 J Therm Anal Calorim DOI 10.1007/s10973-014-3735-1