1. Simulation and Analysis of Equally Distributed Flow for Use in Ultrasonic Atomization Lindsay Rogers University of Wisconsin, Platteville Mechanical Engineering Dr. Chen S. Tsai University of California, Irvine Department of Electrical Engineering and Computer Science Dr. Shirley C. Tsai California State University, Long Beach Department of Chemical Engineering

2. Background  Applications Medical: Pulmonary Drug Delivery Thin, Even Spray Coating  Material Science  MEMS Fabrication (photoresist coating)  Nanoelectronics (deposition of conductor material)  History Bulk Metal-based Ultrasonic Nebulizer Ink-Jet Printer Nozzles (drop-on-demand)

3. Overview  The Nozzle Fourier Horn: half-wavelength design and vibration amplitude magnification of two Constant cross-sectional area of inner channel permits cascading horns Nozzle Holders placed at nodes allowing proper vibration 3-Fourier Horns Transducer Drive Section Nodal Bar Nozzle Holder

4. Ultrasonic Atomization Mechanism  Piezoelectric plate excited, causing the formation of a standing longitudinal wave throughout fluid  Liquid issues from nozzle, creating thin film at tip with capillary wave generated on liquid surface  Operation at resonance causes wave instability and breaks liquid into drops upon ejection  Drop size uniform

5. Advantages  Can operate at higher frequencies than conventional ultrasonic nozzles while requiring less electric drive power  Smaller, more uniform drops  Reduction in overall size  Integration Arrays of multiple nozzles Combine piezoelectric plate application with nozzle fabrication process

6. Array of Nozzles Increase Production of Monodisperse Droplets

7. Manifold  Supply equally distributed fluid flow to each nozzle  Manufactured on same wafer as nozzle array  Optimize parameters including: Junction Angles Length of straight sections and overall length

8. Simulation  ANSYS, finite element software  Utilized program code instead of graphically drawing profile for ease of controlling parameters

9. Analysis  Procedure Model a range of channel profiles by varying optimization parameters Acquire FEM solutions (velocity, pressure drop) Vector Plot of VelocityContour Plot of Pressure

10. Analysis  How results interpreted Visually study plots (velocity, pressure) Minimize overall pressure-drop

11. Results

12. Closing Thoughts  Silicon-based nozzle created which produces monodisperse drops  Manifold of microfluidic channels simulated and optimized  Further work being conducted on channels with more than two branch angles and arrays which don’t follow 2 n pattern (2, 4, 8, 16…)

13. Acknowledgements  Professors Chen and Shirley Tsai  Graduate Students Ning Wang Eugene Huang  National Science Foundation  IM-SURE Program Said Shokair (major props) G.P. Li Goran Matijasevic IM-SURE participants