On-chip implantable antennas for wireless power and data transfer in a glaucoma monitoring SoC

Position of the IOMP SoC in the anterior chamber of the eye.

Loïc Marnat, Mahmoud H. Ouda, Muhammad Arsalan, Khaled Nabil Salama, Atif Shamim

IEEE Antennas and Wireless Propagation Letters Volume: 11, 2012 Page(s): 1671 – 1674 

Abstract: For the first time, separate transmit and receive on-chip antennas have been designed in an eye environment for implantable intraocular pressure monitoring application. The miniaturized antennas fit on a 1.4-mm 3 CMOS (0.18 μm) chip with the rest of the circuitry. A 5.2-GHz novel inductive-fed and loaded receive monopole antenna is used for wirelessly powering the chip and is conjugately matched to the rectifier in the energy-harvesting and storage unit. The 2.4-GHz transmit antenna is an octagonal loop that also acts as the inductor of the voltage control oscillator resonant tank. To emulate the eye environment in measurements, a custom test setup is developed that comprises Plexiglass cavities filled with saline solution. A transition, employing a balun, is also designed, which transforms the differential impedance of on-chip antennas immersed in saline solution to a 50-Ω single-ended microstrip line. The antennas on a lossy Si substrate and eye environment provide sufficient gain to establish wireless communication with an external reader placed a few centimeters away from the eye.