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New and emerging applications of electromagnetic fields

Tid: Må 2024-08-26 kl 13.00 - 16.00

Plats: Ivan Herlitz

Medverkande: Mariana Dalarsson

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Ever since I first started conducting research some 15 years ago, the overall topic of my research has been “new applications of electromagnetic fields”. Over the years, this has led to several research directions: wave propagation in artificial media, and radiofrequency based medical therapies based on gold nanoparticles. Although the relationship between these topics is not immediately obvious to a layman, the theory underlying the topics is essentially the same. Today’s technological society utilizes electromagnetic fields in a great variety of applications. Some of these technologies are now considered as mature. So the focus of my research is on finding new and emerging ways to use the electromagnetic fields, to benefit the society.

My earliest and longest research effort concerns developing new mathematical solutions of Helmholtz’ equation for inhomogeneous graded composites of different materials. This work includes investigating the transmission and reflection properties of structures incorporating negative refractive index materials with graded index of refraction, with and without losses and allowing for arbitrary spectral dispersion. Throughout this work, I have obtained exact analytical solutions to the wave propagation for a number of graded material index profiles. Depending on the geometry studied, the solutions were given in terms of different so-called special functions. My analytical solutions showed an excellent agreement with the corresponding results obtained by numerical simulations, while also reproducing the well-known formulae from classical electromagnetism, in the limiting case of abrupt transitions. Here, the research goal is to create and publish a "library" (or a "toolbox") with all exact analytical solutions for electromagnetic wave propagation in inhomogeneous media of current and future practical interest.

My most recent research efforts concern radiofrequency absorption of gold nanoparticles (GNPs) for medical applications. The research goal here is to find a non-invasive method to treat cancer, by injecting GNPs and subjecting the tissue to an electromagnetic field in the radio frequency spectrum. The GNPs can be coated with folic acid to target the bio-markers that are specific to the cancer cells. Once the GNPs are taken up in the cells, the RF treatment can then cause local heating and cell death only in the cancer, with minimal heating of the surrounding tissue. The long wavelengths of RF radiation have longer penetration depth into tissues than optical frequencies, allowing access to deeper tumor locations. The electromagnetic modeling of coated GNPs is a complex task, with many parameters to be considered. My work has provided detailed models of ligand-coated ellipsoidal GNPs, and the change in RF absorption of such GNPs in tissues has been investigated with respect to coating properties, particle aspect-ratio, and frequency. Both the case of a single nanoparticle and the case of a suspension of GNPs has been studied. The work also includes some thermal analysis and numerical modeling. This research can provide a valuable tool to optimize coated GNP design parameters, in order to secure clinically useful differential heating.