Development of an optoelectrostatic micropump using a focused laser beam in a high-frequency electric field

In this paper, fluid flow generated by laser irradiation in a high-frequency electric field was investigated with a view to using it as the driving force for a micropump. We discovered an optoelectrostatic phenomenon known as optoelectrostatic microvortex (OEMV) ten years ago. The OEMV is generated around the focal point of a laser beam located in the center of an intense high-frequency electric field. The direction of the opposed flow is parallel to the ac electric field and perpendicular to the sides of the electrodes. In this paper, the laser focus was positioned near one of the electrodes. One-directional flow was generated toward the other electrode. This flow was generated in a microchannel by simultaneous application of an Nd:YAG laser (1064 nm) and an ac voltage. The flow velocity increased with both increasing laser power and increasing ac voltage. In addition, the flow velocity was affected by the ac frequency. The flow velocity around the focal point was several hundred micrometers per second. At a distance of 3 mm from the laser spot, a flow velocity of 25 μm/s (0.74 μL/s) was observed.