Direct Laser Interference Patterning (DLIP) was used to modify poly-hydroxyethyl-methacrylate (PHEMA) polymers and Safrofilcon-A hydrogels. These polymers are commonly used as soft contact lenses. The structuring process was carried out by using pulsed laser sources emitting at laser wavelengths in the UV-Visible range and pulse duration in the pico-second and nano-second range. Laser features and optical configuration was modified to achieve optimal structuring conditions. Also, these polymers were structured by using Direct Laser Writing (DLW) to compare both laser structuring techniques. Topography of the structured areas was evaluated by means of confocal microscopy, and micro-Raman spectroscopy was used to assess the microestructural and chemical properties of the laser-structured areas. Finally, optical characterization was carried out in the processed areas to evaluate the modification of the refractive index. DLIP was found to be more efficient, resulting in refractive index changes up to one order of magnitude higher than those obtained by using DLW. In addition, the processing time to produce the structured areas by using DLIP was nearly 3 orders of magnitude faster than using DLW. Hydration properties of DLIP-structured areas were evaluated by using static water contact angle (WCA) measurements with deionized water droplets. Hydration process was found to be similar to non-structured areas.
Results were disseminated in international conferences such as E-MRS Spring Meeting 2019, LPM 2020, and MSE 2020, and published in international journals such as Applied Sciences, Polymers, Proceedings of the LPM2020, and Journal of Laser Micro/Nanoengineering.
