title: Single microdroplet ejection using an ultrasonic longitudinal mode with a PZT/tapered glass capillary.
abstract: We have developed an ultrasonic PZT/tapered glass capillary resonant actuator that can eject a single droplet every acoustic cycle without also generating satellite droplets. The mechanism of the actuation is resonant longitudinal motion-induced squeezing of a tapered volume. The actuator is driven at 160 kHz and requires voltages less than 2 Vpp to operate. In this paper, the droplet generation of isopropanol and water mixtures, which have different densities, viscosities, and surface tensions, is investigated. It is determined that the geometrical squeezing mechanism and the ejected jet breakup makes the droplet size independent of frequency, but more a function of the ejecting orifice diameter that is much smaller than the capillary wavelength.
authors.affiliation: School of Electrical and Computer Engineering, Cornell University, Ithaca, NY 14350, USA.
authors.forename: Chung-Hoon
authors.initials: CH
authors.lastname: Lee
authors.forename: Amit
authors.initials: A
authors.lastname: Lal