A Microfluidic Contact Lens With Optimized Channel Placement for Enhanced Sensitivity for Continuous Intraocular Pressure Monitoring

Abstract

Monitoring continuous intraocular pressure (IOP) is essential for the diagnosis and management of glaucoma; however, current microfluidic sensing techniques lack design optimization and leave substantial room for improvement. In this study, we present a highly sensitive microfluidic contact lens designed to transform intraocular deformation into measurable fluid displacement. The device incorporates a wide reservoir channel, coupled to a narrow indicator channel, enabling amplified displacement, while an integrated air reservoir improves the overall sensitivity. The lens is fabricated using Ecoflex-0030, a soft and biocompatible elastomer with a low Young’s modulus whose strain responsiveness surpasses conventional polydimethylsiloxane (PDMS)-based microfluidic contact lenses. Experimental evaluations using a synthetic eye model demonstrate the highest displacement sensitivity reported to date for microfluidic contact lens sensors, with consistent performance validated through repeated trials and cyclic pressure testing. To further improve device performance, a comprehensive microchannel-location study was conducted that revealed strongly nonuniform strain distributions across the corneal surface. Four lens designs with varying microchannel locations were fabricated and extensively tested to obtain the ideal location for microchannel placement. The sensitivity characterization revealed substantial variation across the different channel locations, with values of 0.5057,1.032, 0.775, and 0.614 mm/mmHg observed for the designs D6, D7, D8, and D9 (at 6, 7, 8, and 9 mm diameter), respectively. The final optimized layout of D7 produced a superior response, reaching 1.032 mm/mmHg, which surpasses previously reported performance in microfluidic contact lenses. These findings demonstrate the importance of mechanical coupling and structural optimization to obtain a highly sensitive and reliable sensor.