Contact lenses are ubiquitous biomedical devices used for vision correction and cosmetic purposes. Their application as quantitative analytical devices is highly promising for point-of-care diagnostics. However, it is a challenge to integrate nanoscale features into commercial contact lenses for application in low-cost biosensors. A neodymium-doped yttrium aluminum garnet (Nd:YAG) laser (1064 nm, 3 ns pulse, 240 mJ) in holographic interference patterning mode was utilized to produce optical nanostructures over the surface of a hydrogel contact lens. One-dimensional (925 nm) and two-dimensional (925 nm × 925 nm) nanostructures were produced on contact lenses and analyzed by spectroscopy and angle-resolve measurements. The holographic properties of these nanostructures were tested in ambient moisture, fully hydrated, and artificial tear conditions. The measurements showed a rapid tuning of optical diffraction from these nanostructures from 41 to 48°. The nanostructures were patterned near the edges of the contact lens to avoid any interference and obstruction to the human vision. Theformation of 2D nanostructures on lenses increased the diffractionefficiency by more than 10%. The versatility of the holographic laserablation method was demonstrated by producing four different 2D nanopatterngeometries on contact lenses. Hydrophobicity of the contact lens wascharacterized by contact angle measurements, which increased from59.0° at pristine condition to 62.5° at post-nanofabrication.The holographic nanostructures on the contact lens were used to sensethe concentration of Na+ ions. Artificial tear solutionwas used to simulate the conditions in dry eye syndrome, and nanostructureson the contact lenses were used to detect the electrolyte concentrationchanges (±47 mmol L–1). Nanopatterns on a contactlens may be used to sense other ocular diseases in early stages atpoint-of-care settings.
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