Faraday instability-based micro droplet ejection for inhalation drug delivery.

We report here the technology and the underlying science of a new device for inhalation (pulmonary) drug delivery which is capable of fulfilling needs unmet by current commercial devices. The core of the new device is a centimeter-size clog-free silicon-based ultrasonic nozzle with multiple Fourier horns in resonance at megahertz (MHz) frequency. The dramatic resonance effect among the multiple horns and high growth rate of the MHz Faraday waves excited on a medicinal liquid layer together facilitate ejection of monodisperse droplets of desirable size range (2-5 µm) at low electrical drive power (<1.0 W). The small nozzle requiring low drive power has enabled realization of a pocket-size (8.6 × 5.6 × 1.5 cm3) ultrasonic nebulizer. A variety of common pulmonary drugs have been nebulized using the pocket-size unit with desirable aerosol sizes and output rate. These results clearly provide proof-of-principle for the new device and confirm its potential for commercialization.

In situ preparation of an ultra-thin nanomask on a silicon wafer.

Porous nanomasks have been prepared in situ on an insulating silicon wafer by anodization of an aluminum film grown on it. Ultra-thin nanomasks, around 50 nm thick, were fabricated by utilizing a stop signal, a vivid color appearing at the air-electrolyte interface, and the process involved showed excellent repeatability. Finally, 2D nanoscale p-n junction arrays were fabricated on a silicon on insulator (SOI) wafer using the ultra-thin nanomasks prepared. The experimental results are in good agreement with the simulated results on the characteristics of the anodization process involved.