Liquid-alloy-based dual sensing elements contact lens sensor for continuous intraocular pressure monitoring

Intraocular pressure (IOP) fluctuation is an independent risk factor for glaucoma and a key to clarify its pathogenesis. We have developed a contact lens integrated with a conformal LC resonance circuit made of liquid alloy (Galinstan) for non-invasive continuous IOP monitoring. The contact lens is fabricated using polydimethylsiloxane (PDMS), in which the LC resonance circuit can sense corneal strain proportionally caused by IOP variation. The Galinstan configuration is formed to the designed pattern by UV-laser treating the carbon- doped Ecoflex (c-Ecoflex) stamps and then selectively transferring the Galinstan onto the stamp to form the LC resonance circuit pattern. The tests conducted on silicone model eyes demonstrate high sensitivity in the frequency responses to variations in IOP, reaching 649 ppm/mmHg. IOP measurement on human eyes during head-down tilt bedrest confirms its applicability. With process optimization, this contact lens sensor has great potential for mass production and wide application in monitoring IOP.