Computational approach to investigating acoustic response of aerogels to ultrasound waves in aqueous and non-aqueous environments

Aerogels are a highly porous and lightweight materials with a unique combination of physical and chemical properties that can be customized for specific applications [1]. Tunability of key parameters such as pore diameter, Young’s modulus, bulk density, and thermal and electrical conductivity have been shown [2]. The range of aerogel’s applications have significantly grown in the last few years. The low density which characterizes aerogels is correlated to their high acoustic impedance, allowing the noninvasive tracking and monitoring of in vivo aerogel implants using routine diagnostic ultrasound techniques.. Most of the work conducted so far has been experimental in nature [ S Ghimire et al, 2021] and as such has been able to only explore a limited parameter space. Experimental work has been limited by the complexity of the experimental setup and detection mechanism needed to accurately map the wave-aerogel interaction and wave propagation behavior.

Here, the authors present a computational approach to studying the acoustic response of aerogels to ultrasound waves in two different environments, aqueous and non-aqueous. Using K-wave, MATLAB tool acoustic wave propagation via aerogel structure were simulated to obtain absorption, transmission and attenuation characteristics. Aerogels with densities in the range of 50 – 200 kg/m3 and porosities in the range of 0 - 70 % were investigated. The Attenuation and transmission loss behavior was studied for sound waves in the frequency range of 0.5 – 1 MHz. Extremely low-density aerogels (50 kg/m3) suspended in air were found to have very low transmission loss with opposite results for the same aerogel when submerged in water. Overall, a computational approach of determining acoustic properties of aerogels has been developed and investigated thoroughly.