High resolution implantable wireless MEMS intraocular pressure sensor

The present work shows the design, simulation and fabrication of a high resolution wireless passive Micro-Electro-Mechanical System (MEMS) for intraocular pressure (IOP) measurements. This sensor was designed and simulated using the finite elements analysis software COMSOL. A MEMS parallel-plates capacitor and a planar inductor were used to form an LC resonator. On the sensing process, the intraocular pressure compresses the MEMS capacitor and changes the sensor´s resonance frequency. This variation is directly related with the internal pressure of the eye. An external coil (antenna) is used for wireless powering and readout. The fabrication and characterization processes were carried out at the Clean Room Laboratory of the Universidad de los Andes. The Sensor fabrication materials were: fiberglass (FR4), copper and polydimethylsiloxane (PDMS). The sensor was tested from 0 to 40 mmHg showing a 160 kHz/mmHg sensibility. Sensor implantation surgery was successfully performed in a rabbit´s eye at Clinica Barraquer in Bogotá. The rabbit has not shown any complications within three months after the surgery.