Detection of Neural Activity of Brain Functional Site Based on Microwave Scattering Principle

A method of detecting brain neural activity with the microwave transmission technology is presented in this paper. This method is based on the fact that the dielectric properties of brain functional site vary with the electrophysiological neural activity. The analysis of the uniform plane wave propagation of dynamic layered medium shows that the phase change of transmission coefficient (S-parameters) is consistent with the variation frequency of permittivity in the dynamic dielectric layer. A 3D head model was introduced to assign dynamic dielectric properties to the cerebral cortex by embedding a tissue piece in this head model. A six-element horn antenna array around the head model was designed, and two types of brain activity at various locations (visual cortex and auditory cortex) inside the head model has been discussed. The simulation results of microwave scattering in different directions show that forward scattering has better applicability. The frequency of the permittivity variation associated with the brain neuronal activity (10 Hz, 20 Hz) can be extracted from the phase variation on S-parameters. In addition, the specific absorption rate analysis ensures the safety of using the microwave in the design of human head detection systems.