Dual-Port Planar Antenna for Implantable Inductively Coupled Sensors

Passive implantable sensors have received considerable attention for wireless <italic>in vivo</italic> measurement of physiological parameters in challenging locations of the human body. They are considered promising alternatives to the existing catheter-based biomedical transducers and battery powered implants. In this paper, we report a novel planar reader antenna for wireless interrogation of <inline-formula> <tex-math notation="LaTeX">$LC$ </tex-math></inline-formula>-based passive implantable sensors. The antenna utilizes two planar, electromagnetically isolated loops for wireless detection of the resonance frequency of the <inline-formula> <tex-math notation="LaTeX">$LC$ </tex-math></inline-formula> sensors. 2-D and 3-D versions of the antenna with the identical geometry were developed for a comparative study. A comprehensive analysis of the antenna together with <italic>in vitro</italic> evaluation of the antenna performance is presented. With the proposed antenna topology, the isolation level of 58 dB within the frequency range of 1–50 MHz, and at least 37 dB up to 100 MHz was achieved. The 3-D version of the antenna demonstrated improved performance by the T/R isolation of at least 64 and 44 dB within the frequency bands of 1–50 and 50–100 MHz, respectively.