Abstract
Our theoretical findings on instability of Faraday waves at megahertz (MHz) drive frequency and realization of silicon-based MHz multiple-Fourier horn ultrasonic nozzles (MFHUNs) together have enabled generation of mono-disperse droplets of controllable diameter (2.5-6.0 μm) at very low electrical drive power (<0.5 Watt). The resulting battery-run clogging-free droplet generator has imminent application to pulmonary (inhalation) drug delivery and other potential applications. Here an update of advances on analysis and design of the MHz MFHUNs and the underlying physical mechanism for generation of mono-disperse micro droplets, and the nebulizer platform for application to detoxification of cyanide poisoning are presented.
Highlights
A number of ultrasonic techniques for generation of micro droplets, for examples, the micro-machined droplet generators based on a liquid horn structure (Meacham et al, 2004) and piezo-electrically actuated flex-tensional micro-machined transducers (Perçin et al, 2002; Kwon et al, 2006) were reported
We present a new technique for generation of controllable monodisperse droplets of desirable diameter range (2.5 to 6.0 μm) using Faraday waves excited by ultrasound with MHz multiple-Fourier horns (MFHs) in cascade and in resonance
The underlying physical mechanism for Faraday wave formation and amplification, was studied extensively based on Faraday’s planar geometry, but mostly at very low drive frequencies ranging from tens to thousands hertz (Hz)
Summary
A number of ultrasonic techniques for generation of micro droplets, for examples, the micro-machined droplet generators based on a liquid horn structure (Meacham et al, 2004) and piezo-electrically actuated flex-tensional micro-machined transducers (Perçin et al, 2002; Kwon et al, 2006) were reported. See the references cited in (Cerda and Tirapegui, 1997; Tsai and Tsai, 2013) At such low drive frequencies, various standing-wave patterns were observed when the vibration amplitude (displacement) on the solid surface reached the onset threshold for Faraday wave formation. In the few reports on experiments at such low drive frequencies droplet ejection was found to take place only when the vibration amplitude on the solid surface was much higher than the onset threshold for Faraday wave formation (Yule, 2000). Our recent discovery as presented here shows that at the much higher drive frequencies of MHz the onset threshold for Faraday wave formation is much lower and the vibration amplitude required for subsequent droplet ejection is only slightly higher than the onset threshold for Faraday wave formation
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call