Design and fabricate a contact lens sensor with a micro-inductor embedded for intraocular pressure monitoring

This paper presents a new type of micro-inductor sensor for intraocular pressure (IOP) measurement on soft contact lens substructure. The sensor was designed and fabricated by using MEMS fabrication technologies. The contact lens is for wearing on a cornea such that a curvature of the contact lens corresponds substantially to that of the cornea, and is preferably made of Hydroxyethylmethacrylate (HEMA) by cast-molding method of soft contact lens for high oxygen permeability and comfortable long-duration wearing. In this paper, we discuss a contact lens with micro-inductor measurement principle followed by a brief description of our sensor design and fabrication. Our first prototype without wireless has been tested in lab-simulation bench. We obtain a simulation and measurement results have good linearity between micro-inductor radius variation and oscillation frequency. In future work will be to optimize the fabrication technology and the design to reach a better resolution, also a radio frequency integrated circuit (RFIC) and antenna will be designed preferably embedded in the contact lens so that inductance value transfers to frequency value via LC oscillator circuit and transmits intraocular pressure sensing signal by wireless telemetry system.