An Efficient Non-Invasive Waveguide-Based Horizontal Impinging of Microwaves for Efficient Power Transfer in Human Body

The paper presents a non-invasive wireless power transfer technique that facilitates horizontal propagation of electromagnetic (EM) waves within the tissue layer of the human body. The horizontal propagation is achieved by using a modified aperture open-ended circular waveguide as the radio front-end and a wave launcher for impinging the EM wave at a desired angle. The EM wave, then with a dominant horizontal component, takes advantage of the sub-dermal fat channel, a parallel plate-like channel formed by the sandwiched low dielectric fat layer between the high dielectric skin and muscle layer. This horizontally propagating wave can be utilized to power multiple implants from a single external source for overcoming the challenges associated with transmitter-receiver alignment in medical implants. The wave launcher is designed for an operating frequency of 2.4 GHz, which is in compliance with the ISM band, and attributed to the optimal frequency for through-body power transfer. This paper further contains an elaborate discussion on the design of the wave launcher including the SMA to wave launcher transition and the results of its numerical study. The design is then validated based on the return loss and electric field intensity in the multilayer heterogeneous medium replicating the human tissues.