Exploring pulse-voltage-triggered optically induced electrohydrodynamic instability for femtolitre droplet generation

Abstract

We present a multipoint "virtual dispenser" to draw femtolitre droplets from a dielectric fluidic thin film using pulse-voltage-triggered optically induced electrohydrodynamic instability (PVT-OEHI). The "virtual dispenser" generates instability nucleation sites by controlling the optically induced lateral electrical stress and thermocapillary flow inside an optoelectronics chip. A time scale analysis shows that the electrohydrodynamic (EHD) instability phenomenon is present; however, its external manifestation is suppressed by OEHI. We observed two droplet dispensing mechanisms which correspond to different EHD states: Taylor cone formation and optically induced EHD jet. The EHD states transition could be realized by adjusting the pulse voltage parameters to alter the morphology of dispensed micron-scale polymer droplets, which could then be formed into organized arrays of microlenses with controllable diameter and curvature based on surface tension effect. © 2014 AIP Publishing LLC.