Characterization of micromachined acoustic ejector and its applications

This paper presents the performance characterization and optimization of micromachined acoustic ejectors (MACE) and their application in micro propulsion and gas pumping. The MACE array utilizes forced Helmholtz resonators coupled with an acoustic ejector to produce high-speed micro-jets at resonance. A micro-jet with "near-field" velocity of /spl sim/0.8 m/sec is measured by hot-wire anemometry. An average thrust of 1.35/spl mu/N per ejector has been obtained consistent with the prediction by theory. A visualized air column longer than 10cm is also demonstrated with an equivalent pumping rate of 54 ml/min per ejector (/spl sim/1600/spl mu/m/spl times/1600/spl mu/m). The resonators have been consistently operating for more than 6,000,000,000 cycles without failure.