We developed a surface acoustic wave (SAW) atomizer, which can produce a narrow mist spray of submillimeter width. The atomized mist spray converges spontaneously and thus requires no additional spray converging system. Key features in achieving the self-converging atomization are two-port interdigital transducers (IDTs) with a groove in between. The SAW is driven by applying an electric field on IDTs patterned on a piezoelectric substrate. The two-port IDTs drive SAWs in opposite directions toward the groove, which then separates the SAW-driven streaming on each side of the groove. Two types of self-converging atomizer were experimentally demonstrated, a line and a point atomizer. While the former uses parallel IDTs to atomize water from the groove into a thin-planar-shaped spray, the latter uses arc-shaped SAW lenses to focus the SAW into a certain point in the groove to atomize water into a narrow point spray. In addition, by adding a water reservoir, continuous operation of up to 30 s was achieved with the submillimeter narrow point atomizer.
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