Enhancing the Low-Frequency Induction Heating Effect of Magnetic Composites for Medical Applications

Abstract

This study aims to enhance the low-frequency induction heating (LFIH) effect in a thermoplastic polymer doped with iron oxide magnetic particles, which are promising candidates for several medical applications thanks to their confirmed biocompatibility. Two main approaches were proposed to successfully boost the heating ability; i.e., improving the magnetic concentration of the composite with higher filler content of 30 wt %, and doubling the frequency excitation after optimization of the inductor design. To test the magnetic properties of the ferromagnetic composite, a measurement of permeability as a function of temperature, frequency, and particle content was carried out. Thermal transfer based COMSOL simulations together with experimental tests have been performed, demonstrating feasibility of the proposed approach to significantly enhance the target temperature in a magnetic composite. These results are encouraging and confirmed that IH can be exploited in medical applications, especially for the treatment of varicose veins where local heating remains a true challenge.Polymers 2020, 12, 386 2 of 16 because of the electric currents induced by the fluctuating magnetic field. Both effects result in heating of the treated object, but the second is the main heat source in IH processes.Compared to other classical heating techniques, such as flame heating, resistance heating, and traditional ovens or furnaces, IH offers fast, clean, and precise temperature control in a contactless and efficient way. It is one of the most preferred heating technologies in industrial [2], domestic [3], and medical applications [4]. Although the process parameters in many industrial and domestic applications are already well-known, there are still some issues that need further optimization: heating of low-resistivity materials, accurate heating of biological tissues, faster design for complex IH load geometries, and accurate 3D FEA simulation of the whole IH system [5]. The third major area of IH is medicine, and this field is not as mature as industrial or domestic applications. It has lately attracted a great deal of research interest. IH was initially applied only in manufacturing and sterilization of many surgical instruments because it is a clean, fast, and portable heat source.IH has recently started to be introduced in minimally-invasive hyperthermia as a cancer treatment therapy by inducing a temperatures of about 41-45 • C to the cancerous cells [6,7]. In order to precisely deliver the power to the tumor, a ferromagnetic material is usually placed in the area to be treated. This technique efficiently destroys cancer tissue while minimizing the damage to the surrounding healthy cells. Moreover, this local treatment can markedly reduce pain compared to chemotherapy. The frequencies used for hyperthermia are usually inside the margins of radiofrequency (i.e., hundreds of kHz to few MHz) [8,9] or microwaves (hundreds of MHz to 10 GHz); i.e., non-ionizing radiation frequencies. However, frequencies over 100 kHz can produce signifi...

Frequency-induced negative magnetic susceptibility in epoxy/magnetite nanocomposites

“…Especially, our experiment revealed that the Fe 3 O 4 nanopowder exhibits negative susceptibility in the X-band while it shows superparamagnetism at low frequencies [6][7][8][9] . A similar phenomenon was observed on La 0.7 Sr 0.3 MnO 3 nanocomposites 10 and FeNi 3 /C nanocapsules 11 .…”

“…The value of Ŵ f is expected to be constant. (8) give us m r for any direction of the external magnetic field. However, the orientation is randomly distributed in the experiment.…”

Radio Frequency Induction Welding of Silver Nanowire Networks for Transparent Heat Films

“…The operating frequency applied for radio frequency induction heating is usually higher than 20 kHz and in less than 1 MHz, depending on the application. And at frequencies below 100 kHz, the skin depth is large, which makes it inefficient to apply to nanomaterials [ 37 , 47 ]. Therefore, three frequency systems were selected within that frequency range to investigate the effect of induced power and frequency on the change in sheet resistance of the Ag NW network.…”

3D Printing of Flexible Composites via Magnetophoresis: Toward Medical Application Based on Low‐Frequency Induction Heating Effect

“…Previous work demonstrates that by increasing the operating frequency of the magnetic source, it is possible to achieve a higher temperature with a faster response time. [3,32] Particle alignment during fabrication clearly shows enhancement in thermal and magnetic anisotropy. [4] Future works aim to optimize the material and process so as improve the heating effect and thermal transfer.…”

“…The LFIH test results of the printed cubic sample under the horizontal array and Halbach array are shown in Figure . An experimental test bench was described in previous work, [ 32 ] where the 16‐magnet inductor was used to generate a 4200‐Hz magnetic field. It is expecting that the temperature response is the most significant in the preferred direction ( y ‐axis) and the lowest in the z‐direction, regardless of either Halbach or horizontal array, is used during the printing process.…”