Predicting initial nucleation events occurred in a metastable nanodroplet during acoustic droplet vaporization

Abstract

Highlights Initial bubble nucleation in a metastable PFP nanodroplet during ADV was described. The modified CNT combined the phase-change thermodynamics of PFP. The thermodynamics was exactly predicted by the Redlich–Kwong equation of state. The modified CNT eliminated the intrinsic limitations of the CNT. Nanodroplet properties exerted strong influences on the ADV nucleation threshold.

On-demand regulation and enhancement of the nucleation in acoustic droplet vaporization using dual-frequency focused ultrasound

“…A modified classical nucleation theory, as proposed in previous studies [40] , [41] , was used to simulate the ADV nucleation process of a PFP nanodroplet in the dual-frequency ultrasound. At a specific pressure and temperature , the critical radius and work for nucleation was calculated by where is the size-dependent surface tension by considering the effect of the nucleus curvature based on a scaling function [41] , [42] , i.e.…”

“…A modified classical nucleation theory, as proposed in previous studies [40] , [41] , was used to simulate the ADV nucleation process of a PFP nanodroplet in the dual-frequency ultrasound. At a specific pressure and temperature , the critical radius and work for nucleation was calculated by where is the size-dependent surface tension by considering the effect of the nucleus curvature based on a scaling function [41] , [42] , i.e. where is the temperature-dependent surface tension of flat interface [43] , and is a normalized degree of liquid metastability determined by the local pressure in the PFP nanodroplet, the vapor pressure in the nucleus, and spinodal pressure of the metastable phase, which are given by where , , , and …”

Ultrasound-Responsive Systems as Components for Smart Materials

“… 211 Thus, when the liquid droplet is exposed to physiological temperatures, it becomes metastable and readily transitions to the gas phase upon excitation with ultrasound. 212 This process, known as acoustic droplet vaporization (ADV), 213 , 214 causes a dramatic change in size. Depending on composition, nanosized liquid droplets with diameters of 200–300 nm can expand into 1–5 μm gas bubbles.…”

“…Commonly used materials for the core are perfluorocarbons (PFCs), because they are nontoxic and have low solubility in water, improving the lifetime of the droplets. , PFCs are volatile compounds: for example, the boiling temperature T b of perfluoropentane (PFP) is 29 °C and that of perfluorohexane (PFH) is 56 °C . Thus, when the liquid droplet is exposed to physiological temperatures, it becomes metastable and readily transitions to the gas phase upon excitation with ultrasound . This process, known as acoustic droplet vaporization (ADV), , causes a dramatic change in size.…”

Recent trends of contrast agents in ultrasound imaging: a review of the classifications and applications

“…ADV has a higher penetration depth, and it is consequently more efficient in phase transformation. [41][42][43] Some of the USCAs containing solid cores are summarized in Table 2.…”