An Exploratory Study for the Design of Transcutaneous Antennas for High Data-rate Full-duplex Applications

Here we present a study on antenna designs aimed at supporting low energy and ultimately very high data-rate (100 Mb/s to Gb/s) transcutaneous wireless links. Such links can enable implantable biosensors as well as multi electrode sensing and stimulation arrays for electromyography (EMG) and functional electrical stimulation (FES) and the associated microelectronics. Thus, the design and performance of a dihedral reflector backed miniaturized dipole antenna (DADR) is examined as a proof of concept for transdermal applications and compared with a common microstrip patch antenna approach for carrier frequencies ≤ 10 GHz. For this study the dielectric properties of animal tissue samples were measured and data representing the frequency dependent losses are modelled in a simulation environment. A performance comparison involving the tissue models is conducted between the proposed DADR and conventional microstrip antenna. The study is conducted by utilising a high operating frequency with a view to enable significantly enhanced data rates as necessary for multi-electrode arrays featuring tens to thousands of individual signals. The proposed transcutaneous reflector-dipole antenna pair achieved an end-to-end propagation loss of 7.53 dB (17.66% power transfer ratio) at 8.4 GHz through a 3 mm thick tissue sample. By comparison, a microstrip-to-microstrip antenna propagation loss was 11.5 dB (7% power transfer ratio). This is an important evaluation for both link-budget calculations and subsequent design of minimum implant electronics and transceiver power dissipation, and for specific absorption ratio (SAR) purposes.