Tunable mirolens array with a large fill-factor: Self-assembly fabrication and electrodrodynamic actuation

Because a tunable microlens can focus the incident light and shift the focal point, a tunable microlens array (TMLA) with a large fill-factor was fabricated by a self-assembly method. Interestingly, each microcavity was filled completely with a liquid droplet, forming a hemispherical profile by capillary forces. The TMLA had a large fill-factor of up to 98% and various sag heights. Moreover, when a gated square-wave voltage was applied, the focal length of TMLA could be tuned from the initial 540 μm to 140 μm by electrohydrodynamic force simultaneously; both of the rise and decay time were within 50 ms. These results indicate that this novel method can construct TMLA with a large fill-factor, thus providing a new perspective towards portability, miniaturization, and low-cost applications.