Assessment of Functional and Biological Compatibility of Antenna in a Head-Mountable DBS Device Using a Rat Model

Abstract

This paper presents a compact planar dipole antenna and an investigation of the interaction of the antenna used in a head-mountable passive deep brain stimulation device and a rat model in two aspects: functional and biological. The functional aspect examines the influence of the rat model on the antenna parameters including refection coefficient, efficiency, and radiation pattern whereas the biological aspect examines the impact of the antenna on the rat model in terms of specific absorption rate, and electromagnetic field distribution. The investigation is carried out with the aid of rat models and a planar dipole antenna which receives the RF energy at 915 MHz for supplying power to a passive DBS device. Both the analytical and simulation results are presented and discussed. The simulation results are obtained by using the electromagnetic simulation software XFdtd. The simulated results show that the complete rat model has more influence on the antenna performance than the rat head model. The electromagnetic power absorption in biological tissues of the rat model depends on the gap distance between the antenna and the position of tissue, and the dielectric properties of the tissues. The maximum electric field value is obtained in the skull of the rat head model, and in the slice of the skull in the complete rat model. The highest 1 g average SAR value for the rat head model is 60 W/kg whereas that for the complete rat model is 101.45 W/kg for the received power of 1W at the antenna terminal. Keywords: DBS, energy harvesting, head-mountable device, passive DBS device, SAR and EM fields.