Acoustic droplet vaporization

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Acoustic droplet vaporization (ADV) is the process by which superheated liquid droplets are phase-transitioned into gas bubbles by means of ultrasound. Perfluorocarbons and halocarbons are often used for the dispersed medium, which forms the core of the droplet. [1] The surfactant, which forms a stabilizing shell around the dispersive medium, is usually composed of albumin or lipids. [1]

In physics, superheating is the phenomenon in which a liquid is heated to a temperature higher than its boiling point, without boiling. This is a so-called metastable state or metastate, where boiling might occur at any time, induced by external or internal effects. Superheating is achieved by heating a homogeneous substance in a clean container, free of nucleation sites, while taking care not to disturb the liquid.

Phase transition transitions between solid, liquid and gaseous states of matter, and, in rare cases, plasma

The term phase transition is most commonly used to describe transitions between solid, liquid, and gaseous states of matter, as well as plasma in rare cases. A phase of a thermodynamic system and the states of matter have uniform physical properties. During a phase transition of a given medium, certain properties of the medium change, often discontinuously, as a result of the change of external conditions, such as temperature, pressure, or others. For example, a liquid may become gas upon heating to the boiling point, resulting in an abrupt change in volume. The measurement of the external conditions at which the transformation occurs is termed the phase transition. Phase transitions commonly occur in nature and are used today in many technologies.

Ultrasound vibrations with frequencies above the human hearing range

Ultrasound is sound waves with frequencies higher than the upper audible limit of human hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies from person to person and is approximately 20 kilohertz in healthy young adults. Ultrasound devices operate with frequencies from 20 kHz up to several gigahertz.

There exist two main hypothesis that explain the mechanism by which ultrasound induces vaporization. [1] One poses that the ultrasonic field interacts with the dispersed medium so as to cause vaporization in the bubble core. The other suggests that shockwaves from inertial cavitation, occurring near or within the droplet, cause the dispersed medium to vaporize. [2]

Vaporization phase transition from the liquid phase to vapor (either through evaporation or boiling)

Vaporization of an element or compound is a phase transition from the liquid phase to vapor. There are two types of vaporization: evaporation and boiling. Evaporation is a surface phenomenon, whereas boiling is a bulk phenomenon.

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Droplet and droplets may refer to:

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Timothy Leighton Professor of Ultrasonics and Underwater Acoustics at the University of Southampton

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References

  1. 1 2 3 Carson, Paul L.; et al. "Acoustic Droplet Vaporization". University of Michigan Basic Radiological Sciences and Ultrasound Group. University of Michigan. Archived from the original on 16 January 2013. Retrieved 30 June 2013.
  2. Kripfgans, Oliver D. (July 2004). "On the acoustic vaporization of micrometer-sized droplets". Journal of the Acoustical Society of America . 116 (1): 272–281. Bibcode:2004ASAJ..116..272K. doi:10.1121/1.1755236.