1. MEMS-Based Multiple Fourier Horn Silicon Ultrasonic Nozzles for Biomedical Applications

"A miniaturized ultrasonic nozzle capable of producing micrometer-sized monodisperse droplets at high throughput and very low electrical drive power has been realized for inhalation drug delivery."

Current devices for pulmonary drug delivery (e.g., nebulizers, metered dose and dry powder inhalers) suffer from broad aerosol (droplet or particle) size distributions and low throughput, making it difficult to deliver sufficient drug to targeted sites precisely and rapidly; this is particularly true for intubated adults and neonates, for whom drug delivery is currently limited by ventilator tubing and endotracheal tubes. Thus, devices that produce more uniform (e.g. monodisperse) aerosols and that have increased throughput to reduce treatment time, small physical size, and low electrical drive power are severely needed. This research aims to address these needs by developing a miniaturized ultrasonic nozzle to produce micron-sized monodisperse droplets at high-throughput and low electrical drive power.

The micro-electro-mechanical system (MEMS)-based miniaturized silicon ultrasonic nozzle utilizes a new and simple nozzle architecture with multiple Fourier horns in resonance but without a central channel (Fig.1(a)). The centimeter-sized nozzles operate at one to two MHz and a single vibration mode which readily facilitates temporal instability of Faraday waves to produce monodisperse droplets. Droplets of diameter range 2.2 to 4.6µm are produced at high throughput and very low electrical drive power (Fig.1(b)).

1. "MEMS-based miniaturized multiple Fourier-horn ultrasonic nozzles for biomedical applications," C.S. Tsai, R.W. Mao, S.K. Lin, N. Wang, and S.C. Tsai, Lab Chip, 10, 2733-2740, Sept., 2010.
2. "Silicon-Based MHz Ultrasonic Nozzles for Production of Monodisperse Micron-Sized Droplets," S.C. Tsai, C.H. Cheng, N. Wang, Y.L. Song, C.T. Lee, and C.S. Tsai, IEEE Trans. on Ultrasonics/Ferroelectrics and Frequency Control, 56, 1968-1979, Sept., 2009.
3. "Pulmonary Drug Delivery Using Miniaturized Silicon-Based MHz Ultrasonic Nozzles," S.C. Tsai, R.W. Mao, D. Mukai, S.K. Lin, A.F. Wilson, N. Wang, M. Brenner, S.C. George, J.Y. Yang, P. Wang, and C.S. Tsai, presented at 2nd International Conference on Accelerating Biopharmaceutical Development, Coronado, CA, March 9-12, 2009.
4. "Ultrasonic Atomization Using MHz Silicon-Based Multiple-Fourier Horn Nozzles," S.C. Tsai, Y.L. Song, C.S. Tsai, Y.F. Chou, and C.H. Cheng, Appl. Phys. Lett., 88, 014102-1 to 3, Jan 2, 2006 (selected  in the January 16, 2006 issue of Virtual J. of Nanoscale Science and Technology).
5. "High Frequency Silicon-Based Ultrasonic Nozzles Using Multiple Fourier Horns,” S.C. Tsai, Y.L. Song, T.K. Tseng, Y.F. Chou, W.J. Chen, and C.S. Tsai, IEEE Trans. on Ultrasonics/Ferroelectrics and Frequency Control, 51, 277-286, 2004.