In Vivo Testing of Circularly Polarized Implantable Antennas in Rats

Two types of miniaturized circularly polarized (CP) implantable antennas are tested in a rat to investigate the effects of the live tissue on the antenna performance. The two implantable antennas are designed for Industrial, Scientific, and Medical (ISM) (2.4-2.48 GHz) biomedical applications. The first implantable helical antenna is initially designed in a one-layer muscle phantom for ingestible capsule endoscope systems. The second implantable patch antenna is designed in a one-layer skin phantom for wireless implantable devices with a fixed implant position. The footprint of the proposed antennas are π×(5.5)
²
×3.81 mm
³
and 10 ×10 ×1.27 mm
³
, respectively. The two antennas were surgically implanted into the rat at Singapore Institute for Neurotechnology. The measured results in the rat were compared to the simulated ones in the one-layer phantom to evaluate the sensitivity of the antennas.