Channel Impulse Analysis of Light Propagation for Point-to-Point Nano Communications through Cortical Neurons

Recent Brain-Machine Interfaces have moved towards miniature devices that can be seamlessly integrated into the cortex. In this paper, we propose communication between miniature devices using light. A number of challenges exist using nanoscale light-based communication and this includes diffraction, scattering, and absorption, where these properties result from the tissue medium as well as the cell's geometry. Under these effects, the paper analyses the propagation path loss and geometrical gain, channel impulse and frequency response through a line of neurons with different shapes. Our study found that the light attenuation depends on the propagation path loss and geometrical gain, while the channel response is highly dependent on the quantity of cells along the path. Additionally, the optical properties of the medium impact the time delay at the receiver and the width and the location of the detectors. Simulations were conducted for cells that are lined horizontally up to a distance of 450μm using light wavelength of 456 nm and different neuron densities (men's neocortex (25924(±15110) /mm3) and women's (27589(±16854) /mm3)). Based on the simulations, we found that spherical cells attenuate approximately 20% of the transmitted power compared to the fusiform and pyramidal cells (35% and 65%, respectively).