Enhancing acoustic cavitation using artificial crevice bubbles

Zijlstra, Aaldert; Rivas, David Fernández; Gardeniers, Han; Versluis, Michel; Lohse, Detlef

doi:10.1016/j.ultras.2014.10.002

Cited by 44 publications

(22 citation statements)

References 44 publications

(60 reference statements)

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“…For V pp > 200 V the bubble becomes unstable, no steady flow pattern can be observed and therefore measurements were scarce. We interpret such a lack of steadiness in the flow as the transition into the nonlinear oscillation regime, in which the bubble stability is compromised and the generation of daughter bubbles is likely to occur Zijlstra et al 2015). Such a dramatic change in the flow behaviour is a clear advantage of this experimental approach: the transition into the nonlinear regime can be easily found in this way since it is very reproducible for different experimental runs.…”

Section: Streaming Flow Dependence On the Driving Voltagementioning

confidence: 87%

“…At higher acoustic energies, the microbubble oscillations become nonlinear and smaller bubbles are emitted from the bubble's tip (Zijlstra et al 2015). Such regimes greatly enhance sonochemical reactions when compared with conventional sonoreactors (Fernandez Rivas et al 2010, 2012a, 2013b.…”

Section: R Bolaños-jiménez and Othersmentioning

confidence: 99%

“…Experimental set-up Air bubbles are spontaneously trapped in artificial crevices micromachined in silicon substrates (Fernandez Rivas et al 2010;Zijlstra et al 2015). The artificial crevices (or pits) are generated by plasma dry etching on silicon substrates and have a cylindrical shape with 30 µm diameter and 10 µm in depth (see figure 1).…”

Section: Experimental Set-up and Techniquesmentioning

confidence: 99%

“…Such a strategy has been followed by Fernandez Rivas et al (2010Rivas et al ( , 2013b and Zijlstra et al (2015) among others to induce nonlinear oscillations that will provoke the pinch-off of the main bubble into smaller ones. The sonochemical peak performance is typically achieved in such a regime, sometimes refereed as the high-power regime.…”

Section: Bubble's Resonant Frequencymentioning

confidence: 99%

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Streaming flow by oscillating bubbles: quantitative diagnostics via particle tracking velocimetry

et al. 2017

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Oscillating microbubbles can be used as microscopic agents. Using external acoustic fields they are able to set the surrounding fluid into motion, erode surfaces and even to carry particles attached to their interfaces. Although the acoustic streaming flow that the bubble generates in its vicinity has been often observed, it has never been measured and quantitatively compared with the available theoretical models. The scarcity of quantitative data is partially due to the strong three-dimensional character of bubble-induced streaming flows, which demands advanced velocimetry techniques. In this work, we present quantitative measurements of the flow generated by single and pairs of acoustically excited sessile microbubbles using a three-dimensional particle tracking technique. Using this novel experimental approach we are able to obtain the bubble's resonant oscillating frequency, study the boundaries of the linear oscillation regime, give predictions on the flow strength and the shear in the surrounding surface and study the flow and the stability of a two-bubble system. Our results show that velocimetry techniques are a suitable tool to make diagnostics on the dynamics of acoustically excited microbubbles.

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Section: Streaming Flow Dependence On the Driving Voltagementioning

confidence: 87%

Section: R Bolaños-jiménez and Othersmentioning

confidence: 99%

Section: Experimental Set-up and Techniquesmentioning

confidence: 99%

Section: Bubble's Resonant Frequencymentioning

confidence: 99%

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Streaming flow by oscillating bubbles: quantitative diagnostics via particle tracking velocimetry

et al. 2017

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“…The silicon wafers were produced and kindly given to us by Dr David Fernandez Rivas from the Mesoscale Chemical Systems group at University of Twente, Netherlands. See Fernandez Rivas et al (2010) and Zijlstra et al (2015) for further information about the production. The ratio of gap height of the test section to diameter of the surface nuclei is at least 18.…”

Section: Experimental Set-upmentioning

confidence: 99%

Diffusion-driven nucleation from surface nuclei in hydrodynamic cavitation

Groß

Pelz

2017

J. Fluid Mech.

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Investigations about the role of nuclei and nucleation for the inception and formation of cavitation have been part of cavitation research since Harvey et al. (J. Cell. Physiol., vol. 24 (1), 1944, pp. 1-22) postulated the existence of gas filled crevices on surfaces and particles in liquids. In a supersaturated liquid, surface nuclei produce small gas bubbles due to mass transfer of gas or themselves work as weak spots in the liquid that are necessary for a phase change under technically relevant static pressures. Although various theories and models about nuclei and nucleation have found their way into standard literature, there is a lack of experimentally validated theories that describe the process of diffusion-driven nucleation in hydrodynamic cavitation. In order to close this gap we give new theoretical insights into the physics of this nucleation mechanism at technically relevant low supersaturations validated with extensive experimental results. The nucleation rate, the number of produced bubbles per second, is proportional to the supersaturation of the liquid and shows a nonlinear dependence on the shear rate at the surface nucleus. A model for the Strouhal number as dimensionless nucleation rate is derived allowing the estimation of nucleation rates from surface nuclei in hydrodynamic cavitation. The model provides three asymptotes, being a function of Péclet number, Weber number, the supersaturation of the liquid ζ and gas solubility Λ for three different detachment mechanisms, Sr ∝ ζ ΛWe n Pe 1/3 with n = 1/3, 3/4, 1. The theoretical findings are in good agreement with experimental results, leading to a new assessment of the role of diffusion in cavitating flows.

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Surface Wettability of Nanoparticle Modulated Sonothrombolysis

Zhang

Pan

et al. 2021

Advanced Materials

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Sonodynamic therapy (SDT) is a non‐invasive and highly penetrating treatment strategy under ultrasound irradiation. However, uncertainty in the mechanism of SDT has seriously hindered its future clinical application. Here, the mechanism of SDT enhanced by the wettability of nanoparticles is investigated. Nanoparticles can adsorb and stabilize nanobubbles in liquid, thus enhancing SDT efficiency. The stability of the nanobubbles is positively correlated with the desorption energy of the nanoparticles, which is determined by the wettability of the nanoparticles. This conclusion is verified for mesoporous silica and polystyrene nanoparticles and it is found that nanoparticles with a water contact angle of about 90° possess the largest desorption energy. To further apply this conclusion, thrombus models are constructed on rats and the experimental results demonstrate that nanoparticles with the largest desorption energy have the highest thrombolytic efficiency. It is believed that these findings will help to better understand the SDT mechanism and guide new strategies for rational design of nanoparticles adopted in SDT.

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Enhancing acoustic cavitation using artificial crevice bubbles

Cited by 44 publications

References 44 publications

Streaming flow by oscillating bubbles: quantitative diagnostics via particle tracking velocimetry

Streaming flow by oscillating bubbles: quantitative diagnostics via particle tracking velocimetry

Diffusion-driven nucleation from surface nuclei in hydrodynamic cavitation

Surface Wettability of Nanoparticle Modulated Sonothrombolysis

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