The use of left handed materials for the optimization of the focusing attributes of a biomedical hybrid system

Microwave radiometry is a measurement technique that has been used to provide temperature distributions inside the human body. In this context, radiometry has several biomedical applications. Specifically, among others, it can be used to provide temperature control during hyperthermia sessions and detection of temperature variations inside the human brain during brain activation. A novel system able to provide microwave radiometry measurements and hyperthermia treatment has been developed by our group in the past few years. Its main module is an ellipsoidal cavity acting as a beamformer providing the necessary focusing. The cavity is used in conjunction with sensitive radiometric receivers and magnetron generators during microwave radiometry and hyperthermia respectively. In this paper, ways to improve the system´s focusing properties are examined throughout extensive simulation analysis. In particular, low loss dielectric materials are used to fill the cavity´s volume in conjunction with left handed materials used as matching layers around a human head model. Results have shown enhancement of the detection/penetration depth of the electric field inside the human head model as well as improvement of the system´s spatial sensitivity in relative movements of the head model around the ellipsoidal´s focal point.