Wide and fast focus-tunable dielectro-optofluidic lens via pinning of the interface of aqueous and dielectric liquids.

Electrohydrodynamic actuation of dielectric liquid enables the development of an efficient focus-tunable dielectro-optofluidic lens (DOL) by manipulating a liquid-liquid interface. However, practical utilization of the previous DOL is hindered by its narrow and slow focus-tunability due to the direct movement of the interface. Here, we propose pinning the interface to directly change the interface shape while preventing the interface movement. The newly designed DOL exploits sudden changes in the channel diameter and the surface wettability to firmly pin the interface. Our results demonstrate that the tuning range of the DOL from -40 to +35 diopters is achieved in 0.1 s.