Optimum electromagnetic heating of nanoparticle thermal contrast agents at rf frequencies

• DOI: 10.1063/1.3204653
• Publication Date: 2009-09-08T22:46:05Z
• Authors: George W. Hanson; S. K. Patch
• Keywords: 02 engineering and technology; 0210 nano-technology; 7. Clean energy

Enhanced heating of nanoparticles for applications such as thermoacoustic imaging and therapeutic heat delivery is considered. The optimum electrical conductivity to achieve maximum electromagnetic energy deposition in a given nanoparticle is obtained, with emphasis on rf frequencies, where plasmon resonances associated with negative permittivity are generally not possible. Spheres, coated spheres, nanowires, and carbon nanotubes are considered. In all cases, it is found that relatively small conductivity values (e.g., σ⪡1 S/m for spheres) provide the maximum absorption of rf energy, and thus maximizes heat production in the nanoparticle. Therefore, lossy dielectrics may be a better choice for maximizing nanoparticle heat production than metallic particles.