Cavitation, Shock Waves and the Invasive Nature of Sonoelectrochemistry

Abstract

The invasive nature of electrodes placed into sound fields is examined. In particular, perturbations of the sound field due to the presence of the electrode support are explored. The effect of an electrode on the drive sound field (at approximately 23 kHz) is shown to be negligible under the conditions investigated in this paper. However, scattering of shock waves produced by cavity collapse is shown to exhibit a significant effect. To demonstrate this, multibubble sonoluminescence (MBSL) and electrochemical erosion measurements are employed. These measurements show an enhancement, due to the reflection by the solid/liquid boundary at the electrode support, of pressure pulses emitted when cavitation bubbles collapse. To first order, this effect can be accounted for by a correction factor. However, this factor requires accurate knowledge of the acoustic impedance of the interface and the electrolyte media. These are measured for two commonly employed substrates (soda glass and epoxy resin, specifically Epofix). A scattering model is developed which is able to predict the acoustic pressure as a function of position over a disk-like electrode substrate. The effects of shock wave reflection and materials employed in the electrode construction are used to clarify the interpretation of the results obtained from different sonoelectrochemical experiments. Given the widespread experimentation involving the insertion of electrodes (or other sensors) into ultrasonic fields, this work represents a significant development to aid the interpretation of the results obtained.

The acoustic bubble: Oceanic bubble acoustics and ultrasonic cleaning

“…However, it would not be correct to equate the bubble activity in the cleaning bath with that which occurs in the UAS. The ultrasonic cleaning bath causes cavitation, whereby bubbles collapse under ultrasound to generate shock waves [27][28][29] and can also involute to form microjets [30,31], both of which can remove material from surfaces [32,33]. In contrast, the UAS system projects sound down a column of water [34] in order to excite surface waves [35][36][37] on the walls of microscopic bubbles on the surface to be cleaned.…”

The collapse of single bubbles and approximation of the far-field acoustic emissions for cavitation induced by shock wave lithotripsy

“…The maximum pressure recorded varies from nearly 7 GPa for ζ = 1.0625 to a mere 0.5 GPa for ζ = 2.125. It would be a likely candidate to assess for the generation of at least surface damage on a nearby surface, although full assessment of all possible contributions to damage is beyond the scope of this article (Philipp & Lauterborn 1998;Tong et al 1999;Eisenmenger 2001;Zhong et al 2001;Zhu et al 2002;Birkin et al 2005a;Calvisi et al 2007Calvisi et al , 2008Klaseboer et al 2007;Sapozhnikov et al 2007;Iloreta et al 2008;Lauterborn & Kurz 2010;Vian et al 2010).…”

“…The link between these and damage is made through empirical observation of patients (Leighton et al 2008c), and there is no intention here of linking the calculated pressure and flow fields to damage. The search for such a direct linkage is subject to an ongoing and intensive international research effort (Philipp & Lauterborn 1998;Tong et al 1999;Eisenmenger 2001;Zhong, Zhou & Zhu 2001;Zhu et al 2002;Birkin et al 2005a;Calvisi et al 2007;Klaseboer et al 2007;Sapozhnikov et al 2007;Calvisi, Iloreta & Szeri 2008;Iloreta, Fung & Szeri 2008;Lauterborn & Kurz 2010). To be clinically relevant, the output of such research would require challenging extrapolation to clinical tissue from the materials used in laboratory experiments or simulations (e.g.…”

Aplicação do ultra-som em sistemas eletroquímicos: considerações teóricas e experimentais

“…Em uma análi-se de nitrito em ovos 73 , por exemplo, moléculas de proteínas e gorduras presentes nas amostras adsorvem-se na superfície, inativando o eletrodo. Estas moléculas são removidas pelo processo de cavitação 30,74 , efeito chave do processo de limpeza. Entretanto, poucas informações sobre os aspectos fundamentais deste processo são conhecidas.…”