Feeling gassy? Modifying the oxygen partial pressure of a fluid using acoustic droplet vaporization and different droplet concentrations

Abstract

Nucleating acoustic droplet vaporization reduces the dissolved gas content in a fluid. The objective of this study was to determine if the change in the partial pressure of oxygen (Po2) could be modulated by adjusting the concentration of micron-sized perfluoropentane droplets. The droplets were manufactured using high-speed shaking and size-isolated using differential centrifugation (1 to 6 μm in diameter). Droplets were diluted in saline with a Po2 of 154 mmHg and pumped through a 37°C flow phantom at 40 mL/min. The concentration ranged from 3.5×106 to 3.5×108 droplets/mL. A 5 MHz focused transducer insonified droplets at peak negative pressures of 4.05 MPa with a 500-Hz pulse repetition frequency and 5-cycle pulse duration. The Po2 was measured downstream of the insonation region. At the lowest droplet concentration, the Po2 was reduced to 129 mmHg. As the droplet concentration was increased, the Po2 was reduced further. The reduction was in agreement (intra-class correlation and Pearson correlation coefficients greater than 0.9) with the model reported by Radhakrishnan et al. (2016, Ultrason. Sonochem.). At the highest droplet concentration, the Po2 was reduced to 31 mmHg. These results demonstrate that ADV with varying droplet concentration modulates the oxygen partial pressure in a fluid.