Intraocular pressure sensors: New approaches for real-time intraocular pressure measurement using a purely microfluidic chip

In this work, an approach for the monitoring of intraocular pressure (IOP) using a manometer-based microfluidic device is described. This device was designed for periodic monitoring of IOP in patients suffering from glaucoma. The current state-of-the-art IOP measurement technique, a tonometer, lacks accuracy due to unpredictable scleral compliance and variable cornea stiffness between patients. Therefore, a novel approach for IOP measurement is required. In the past few years, MEMS-based sensors have been researched but none are passive, they all require external power supply and involve a complex design. For example, an IOP sensor based on capacitance measurement proposed by Wise [1] and Irazoqui [2] can actively record IOP value, but need a solar battery or wireless charging to fulfill the power requirements. Piezoresistive IOP sensors [3], on the other hand, have shown an inability to integrate an antenna and a battery together and thus are not preferred. Tonometers [4] have been modified to use a soft contact lens to measure the cornea deformation, but the reasons for their inaccuracy have not been resolved.