MEMS-Based MHz Integrated Ultrasonic Nozzles with Applications to Micro/Nano Technologies
S.C. Tsai, Y.L. Song, Y.F. Chou, G. Qiu, E. Degiovanni, N. Wang, J.S. Cheng and C.S. Tsai
University of California, Irvine, US
MEMS, ultrasonic atomization, spray, nozzles
This paper reports on modeling/simulation and design, MEMS-based fabrication of MHz ultrasonic nozzles, and their applications to micro- and nano-technologies. The ultrasonic nozzle is made of a piezoelectric drive section and a silicon-resonator consisting of multiple Fourier horns. Such silicon-based ultrasonic nozzles possess a number of advantages over the commercial 120 kHz bulk-type ultrasonic nozzles, such as MEMS-based micro-fabrication technology for mass production, much higher ultrasonic frequency than the 120 kHz limitation, much smaller drop size and size distribution, and much lower electric drive power requirements. Most recently, actual atomization using such MEMS-based MHz ultrasonic nozzles was also accomplished for the first time. As water is pumped into the 150 um-diameter channel of the nozzle, atomization occurs at the nozzle tip only when the drive signal is at the resonant frequency of 484.5 kHz. Over 60% of the droplets produced have a diameter as small as 7.2 um. Some of the potential applications are: (1) nanoparticles synthesis, (2) thin-film spray coating for micro- and nano-electronics processing, and (3) alveolar delivery of medicines. For example, 60 um ceramic particles have been produced by means of ultrasonic spray pyrolysis. Preliminary results of some of these applications will also be presented.
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Nanotech 2005 Conference Program Abstract