Fabrication of microlens arrays using UV micro-stamping with soft roller and gas-pressurized platform

The conformal contact between the roller stamper and the thin flexible substrate is important for precisive replication of microstructures. In this study, we have proposed a novel mechanism which employs a soft roller stamper and a gas-pressurized platform to fabricate UV-cured polymeric microlens arrays on a continuous flexible substrate. The new facilities constructed in this study comprise a polydimethylsiloxane (PDMS) stamping roller, a gas-pressurized platform and an UV light source underneath the platform. The soft roller was made by casting a pre-polymer of PDMS in a plastic master of microlens array. During the rolling micro-stamping process, the microlens array cavity on the soft roller is first filled with liquid UV-curable resin. The roller stamper then rolls and stamps over the moving transparent thin polymeric substrate which is located on the gas-pressurized platform. At the same time, the UV light irradiates beneath the platform and cures the resin in the rolling zone. Thus, the microlens array patterns are successfully fabricated. The dimensions of the microlens are 115.5 μm in diameter, of, a sag height of 7.88 μm in sag height, and 200 μm in pitch size. This method developed in this work clearly demonstrates its potential of using the soft mold and the gas-pressurized platform for continuous mass production of films with microstructural patterns.