Microscale Analysis of Brain Tissue Interaction with Microwave Radiation

In this work, we studied the effects of electromagnetic fields on biological matter at a micrometer distance. The objective is to estimate and compute the induced electric and magnetic fields within biological, using finite element modeling (FEM) software to analytically quantify the effects and resonances at a wide spectrum of frequencies. Our findings reveal that, within the model considered for sub-THz frequencies, electromagnetic waves induce resonance in micrometer-sized tissue, with the field reaching its peak within the biological substance. This insight is used for determining the effect of microwave radiation on induced electric and magnetic fields in the context of both brain stimulation applications and brain sensing. Consequently, the interaction between gray matter tissue and microwave radiation is studied to verify the feasibility and the power density requirements of arrays of nanomagnetic devices to stimulate neuron cells within approximately 100 µm distance. It is well-established that GHz frequencies can exert and promote inhibitory effects on synapses and suppress brains signals similarly to nano-pulsed electric fields. In this study, we utilized a FEM software to estimate the interaction of the electromagnetic field with specifically gray matter carefully controlling various parameters within the comprehensive model to quantify the effects on a micrometer scale in terms of the induced electric and magnetic field from a microwave source. We also calculate the specific absorption ratio (SAR) for different frequencies ranging from MHz to GHz to examine the magnitude of the effects and their implications on bioheating models.