Flexible, wearable microfluidic contact lens with capillary networks for tear diagnostics

Wearable contact lenses attract great interest as a minimally invasive diagnostic platform. With advances in biomaterials, electronics and microfabrication, contact lenses offer the potential to analyze the concentration of biomarkers of interest in tears. Emerging wearable contact lenses typically involve external electrodes and batteries, signal processing and wireless transmission, which is accompanied by increased stiffness in the contact lenses and do not have direct means for detecting tears or storing small volumes of tears. Here, we developed a UV-curable biomaterial with good biocompatibility, hydrophilicity and elasticity for fabricating flexible, wearable contact lenses. The contact lens defined a set of tear inlets that allowed tears to flow spontaneously through the capillary network and reservoirs. The previously embedded chemical substrates responded via colorimetric methods to biomarkers in the tears, such as glucose, chloride and urea. Then, the external device took pictures and read the RGB values in the photos to obtain the concentration range of the biomarkers. Furthermore, in vitro tests using an artificial microfluidic hydrogel eyeball device demonstrated the convenient and reliable operation of the lens. Our work offers a new paradigm for noninvasive, multi-target microfluidic contact lenses with capillary networks for tear storage and diagnostics. The fabricated contact lens could serve as an immense point-of-care diagnostic platform in the future.