In Vivo Tests of Implantable Antennas in Rats: Antenna Size and Intersubject Considerations

We propose and implement an experimental protocol for in vivo testing of implantable antennas in rats, which aims to quantify dependence of the exhibited resonance performance upon antenna size and intersubject and surgical procedure variability. Two implantable antennas with occupied volumes of 204 and 399 mm³ are tested inside three different rats each. Investigations are carried out in the Medical Implant Communications Service (MICS) band (402-405 MHz). Intersubject and surgical procedure variations are found to quite affect the exhibited reflection coefficient frequency response, with reduction in antenna size further increasing sensitivity. Compared to simulations, maximum deviations in the center resonance frequency within the bandwidth and 10-dB bandwidth equal -6.5% and +30.2% for the 204-mm³ antenna, and -1.7% and -14.9% for the 399-mm³ antenna. Antenna radiation and safety performance are finally assessed for glucose monitoring applications.