Laser Based Manufacturing of Nanotextured Contact Lenses

Abstract

Contact lenses are recently being developed as wearable sensors to detect the biomarkers present in the eye. The techniques available, however, consist of expensive materials and complicated manufacturing process. In this thesis, a commercially viable method of producing nanostructures on the surface of a contact lens using the direct laser interference patterning technique was studied. Contact lenses coated with thin films of black dye, gold, and graphene material were ablated using an Nd:YAG laser at various tilt angles, to produce periodic structures directly on the contact lens. A novel immersion coating method was used to coat graphene on the contact lens. The groove profile of the nanostructures of the different materials was recorded using Scanning Electron Microscopy (SEM). The diffraction and transmission properties of the different nanostructures were compared. A prominent holographic effect has been displayed by all the three materials; however, the graphene film showed a higher adhesion to the hydrogel lens implying a higher stability of the structures. Hence, the graphene nanostructures were further optimized by varying the graphene immersion time of the contact lens. The diffraction efficiencies of these samples were measured and a maximum efficiency of 0.25% was obtained. The contact angle of the nanostructured lenses was measured to determine its hydrophobicity and the values were in the range of 73° – 84.8°. The EWC of the graphene coated lens were found to be in the range of 58 - 70 % with the least hydrophobic sample being the lens with an immersion time of 2 hours. The maximum oxygen permeability obtained had a value of 27 ± 2 Barrer which was comparable to that of the plain lens.

Date of Award	1 May 2024
Original language	American English
Supervisor	HAIDER BUTT (Supervisor)