Sol-gel concave micro-lens arrays fabricated by combining the replicated PDMS soft mold with UV-cured imprint process

Photosensitive TiO₂/organically modified silane organic-inorganic hybrid thin films were synthesized by combining a low-temperature sol-gel process with a spin-coating method. Optical transmittance properties and the photochemical activities of the planar hybrid films were characterized by UV-Visible spectroscopy and Fourier transform infrared spectroscopy. Advantages for fabrication of the concave micro-lens arrays (MLAs) based on the photosensitive hybrid films were demonstrated by using the replicated polydimethylsiloxane (PDMS) soft mold as the imprint mold and a UV soft imprint technique. Morphological and surface profile properties of the master, the PDMS soft molds and the as-fabricated sol-gel concave MLAs were observed by scanning electron microscopy and laser confocal scanning microscopy. Contact angles of water on the PDMS soft molds baked at different temperatures were studied. Optical imaging properties of the as-fabricated concave MLAs were confirmed by a self-made optical test system. Results indicate that the as-prepared photo-patternable hybrid materials have great applicability for the fabrication of photonic components, thus providing an effective method to fabricate concave MLAs based on the as-synthesized hybrid films by combining the UV-cured imprint technique with the replicated PDMS soft mold, which has advantages of simplicity, cost-effective and mass production and potential application in industry production.