Molecular structure dependence of acoustic nonlinearity parameter B/A for silicone oils

Exploring new acoustic parameters is essential to develop a noninvasive imaging technique for the surgery of silicone oil tamponades. In this study, the acoustic nonlinearity parameters B/A of varied silicone oil samples(e.g., linear or hyperbranched) are experimentally measured by using a modified thermodynamic method. The results show that:(i) when the concentration of the silicone oil with a molecular weight of 5 × 104increases from 0.5 g/100 ml to 8 g/100 ml, the corresponding B/A value increases by about 18%, but the acoustic velocity only increases by about 0.1%;(ii) when the molecular weight of the hyper-branched silicone oil is enhanced from 2 × 105to 1 × 106, the B/A value increases by about22%, while the acoustic velocity is only raised by about 0.2%. This study suggests that the B/A parameter of the silicone oil is more sensitive to the change in its molecular structure than that of the acoustic velocity. Thus, the B/A parameter might be utilized as an effective index for the development and optimization of the noninvasive imaging of the surgery of silicone oil tamponades.

Molecular structure dependence of acoustic nonlinearity parameter B/A for silicone oils