Effects of laser light and AC signals on opto-electrohydrodynamic flow with twin microvortices: I. non-uniform AC electric fields

Abstract

Abstract This paper describes both qualitative and quantitative analysis of rapid microvortex flow generation and manipulation induced by opto-electrohydrodynamic technique. A flow named twin opposing microvortex (TOMV) is generated by infrared laser light under non-uniform alternating current (AC) electric fields. For the AC electric fields, frequency ranges from 3 kHz up to 2 MHz while the voltage is changed up to 10 Vp-p (peak-to-peak voltage). Simultaneously, the laser shines either of a pair of electrodes with a power of 0.5 W. Micron-resolution particle image velocimetry technique has been used to construct the velocity fields of the TOMV flow. The strength of the TOMV flow can be tuned by adjusting the AC voltage and frequency. The maximum measurable in-plane velocity of 54.7 µm s−1 outside electrode regions can be achieved with an AC signal of 9 Vp-p and 107 kHz and a laser beam of 0.5 W. This is achieved with indium tin oxide electrodes located on the top surface of a microchamber, in which the electrodes are 16 µm wide and 300 µm long with a spacing of 73 µm between them. This three-dimensional flow generation can be used for in situ micropump and mixing.