Hydrogel-Based Tunable-Focus Liquid Microlens Array With Fast Response Time

We present a hydrogel-driven focus-tunable liquid microlens array on a curvilinear surface with much faster response time than previously reported. Water-oil interfaces pinned at polymer apertures serve as microlenses. Thermoresponsive poly(N-isopropylacrylamide) hydrogel incorporating glycidyl-methacrylate-functionalized graphene oxide is employed to provide faster actuation for focal length tuning. Thermoelectric modules based on Peltier effect were implemented to enhance the heat transfer to and dissipation from the hydrogel actuators. The average response time improves to 5 s, and the focal length ranges from 7 to 120 mm. Simulations were performed to characterize the thermal behavior of the microlens array during actuation. The microlens array is also demonstrated with an ability to be remotely controlled by infrared light.