Electrically driven varifocal micro lens fabricated by depositing parylene directly on liquid

The design and fabrication process of an electrically-driven varifocal liquid microlens are reported with experimental measurement results and a theoretical calculation model. Droplets of oil are sandwitched between a glass wafer and a thin-film of parylene chemical vapor deposited (CVD) directly onto the droplets´ liquid surface. A method for creating fluid-filled micro chambers was realized with two core steps: 1) placing-shaping of oil droplets with hydrophobic/hydrophilic patterns and 2) coating them with a thin CVD parylene film in high vacuum condition. Liquid lenses and lens arrays of diameter from 20 mum to 10 mm were fabricated. In the tuning experiment, focal length was shortened to 20% of its initial value, from 3.8 mm to 0.8 mm. The values calculated from model match the data collected from experiments within the range of applied voltage from 0 V to 150 V.