Fat intra-body communication (Fat-IBC) is a novel communication technique aiming at exploiting the very low electrical conductivity of subcutaneous fat tissue to convey electromagnetic signals among implantable and wearable biomedical devices. This paper describes the design of two on-body antenna solutions, optimized to transmit signals along the body exploiting the subcutaneous fat tissue as a communication channel. The designed antennas have been fabricated and tested on a threelayer phantom model emulating the dielectric properties of skin, fat and muscle, inserted in a portable chamber to reduce external interference and minimize alternative propagation paths, i.e., outside the fat channel. Preliminary data rate transmission measurements computed using two Raspberry Pi units allowed link speeds in the range of 90 Mbps for one of the two considered antenna pairs, demonstrating the ability of the designed solution to efficiently couple the radiation into the tissue-mimicking phantoms and transmit signals through the fat layer.

Fat intra-body communication (Fat-IBC) is a novel concept of communication through the low-loss fat tissue layer of the body. This new data transmission approach is promising for the implementation of wireless, in-body, bidirectional Brain-Machine-Body connectivity, which will profoundly impact different fields, such as brain implants with read/write capability and human-like artificial sensors and limbs. In this paper, we apply an evolutionary algorithm combined with a full-wave electromagnetic solver to optimize a flat epidermal antenna, to improve the radiation coupling into the body and favor the signal transmission in the subcutaneous fat layer. The application of this method to a skin-fat communication channel shows satisfactory results when both the antennas of the link are considered and materials with high relative permittivity are used. A good radiation coupling into the body is observed, and transmission losses lower than 5 dB/cm are achieved.