Laser-induced bubble formation on a micro gold particle levitated in water under ultrasonic field

Significance 

Recent technological advances have revealed that high-power laser has potential to breakdown liquid. Such a process is generally characterized by fast plasma formation after evaporation of the liquid and subsequent vapor expansion accompanied by shockwave emission. In addition, the velocity of the bubble wall after the shock departure has been seen to be adequate to enable emission of light at the collapse point. A recent publication has highlighted that bubble formation on the surface of gold nanoparticles irradiated by a high-power laser in water possesses excellent attributes that have potential application in medicine, specifically: in cancer treatment and therapy. Unfortunately, a daunting challenge has been encountered in attempts to perform experiments that could yield good results since the dispersed gold nanoparticles are very difficult to control.

To this note, Professor Jaekyoon Oh, Mr. Yungpil Yoo and Professor Ho-Young Kwak at Chung-Ang University in collaboration with Professor Samsun Seung at Kangwon National University managed to resolve the aforementioned shortcoming by attempting to levitate a micro gold particle at the center of a spherical flask filled with water under ultrasound. They provided an alternative technique that would free up the locked potential and enable versatile applications, specifically in medicine. Their work is currently published in the research journal, Experimental Thermal and Fluid Science.

In brief, the research method applied entailed visualization by use of high-speed cameras, of the bubble formation, its subsequent growth and collapse, for the levitated micro gold particle. Next, the researchers utilized a needle hydrophone at various positions from the center of the flask to measure the strength of shock emitted during the expansion of the bubble formed on the gold particle. In the theoretical study, the time-dependent radius of the laser induced bubble with/without gold particle was obtained using solutions of the Navier-Stokes equations for the vapor inside the bubble and the liquid adjacent to the bubble wall. Lastly, the shock strengths at various points were obtained using the Kirkwood-Bethe hypothesis with the obtained time-dependent bubble radius and the pressure at the bubble wall.

The authors observed that the maximum radius reached by the bubble formed on a gold particle was approximately 0.65 mm while the maximum radius from a laser-induced bubble without the gold particle was approximately 0.45 mm at the same laser energy input for both cases. Additionally, they noted that the shock strength during the expansion stage from the bubble formed on the gold particle was seen to be greater than that from the laser induced bubble without the gold particle.

In summary, the study successfully presented an in-depth theoretical and experimental analysis of a laser induced bubble formation on a micro gold particle levitated at the center of a spherical flask filled with water under ultrasound. In general, using the high-speed cameras, a homologous behavior for laser induced bubble in liquid and laser induced bubble on levitated gold micro particles was observed. Altogether, their study has provided a way to carry out experiments and obtain good data regarding bubble formation on the surface of laser-irradiated gold micro particles thereby opening novel medical paths.

Laser-induced bubble formation on a micro gold particle levitated in water under ultrasonic field - Advanced Engineering
Fig. 3 Formation, subsequent growth and collapse of a bubble formed on a gold particle (G-bubble) by laser irradiation of 7.5 mJ. Frame rate is 374532 per second.
Laser-induced bubble formation on a micro gold particle levitated in water under ultrasonic field - Advanced Engineering
Fig. 4 Formation, subsequent growth and collapse of a bubble formed by laser irradiation (L-bubble) of 7.5 mJ without the gold particle. Frame rate is 374532 per second.
Laser-induced bubble formation on a micro gold particle levitated in water under ultrasonic field - Advanced Engineering
(a)
Laser-induced bubble formation on a micro gold particle levitated in water under ultrasonic field - Advanced Engineering
(b)
Laser-induced bubble formation on a micro gold particle levitated in water under ultrasonic field - Advanced Engineering
(c)
Fig. 5a Snapshots of bubble formation, growth and collapse for several cases of an L-bubble (a) and G-bubbles (b and c) with a laser energy input more than 7.5 mJ.
Frame rate is 86505, 84531and 53763 per second for (a), (b) and (c), respectively.
Laser-induced bubble formation on a micro gold particle levitated in water under ultrasonic field - Advanced Engineering
Fig. 5b Bubble formation, growth and collapse for a G-bubble with a laser energy input of 30 mJ.

About the author

Jaekyoon Oh Professor, Department of Automotive Engineering at YIT (Yeoju Institute of Technology), Korea. He had developed automobiles since 1992 as a product engineer at Hyundai motors and GM Korea and head of business development at Magna electronis, ABC group and IEE for 25 years.

His research interests are in heat & fluid engineering system and new business development of automotive engineering. Respect engineering faculty, received B.S. from Chung-Ang University in 1988, M.A. and Ph. D. in mechanical engineering from Chung-Ang University, Korea in 1992 and 2016, business faculty, received MBA from Sogang University in 2001.

About the author

Yungpil Yoo Senior Researcher, Besico. He got master’s degree in mechanical engineering from Chung-Ang University in 2015. His current research field is renewable energy policy, renewable energy system optimization, and exergy analysis.

About the author

Samsun Seung received B.S. from Chung-Ang University in 1981 and M.A. and Ph. D. in mechanical engineering from the Chung-Ang University, Korea in 1983 and 1991, respectively. He joined Department of Mechanical Design Engineering faculty, Kangwon National University at Samcheok, Korea in 1996 and is currently a Professor there. His research interests are in fluid flow phenomena, and heat transfer.

About the author

Ho-Young Kwak received B.S. from Seoul National University in 1971 and M.A. in plasma physics and Ph.D. in mechanical engineering from the University of Texas at Austin, USA in 1977 and 1981, respectively. He joined M.E.

Faculty, Chung-Ang University, Korea in 1981 and served 35 years and is currently Emeritus Professor there. His research interests are in bubble nucleation and dynamics, sonoluminescence phenomena, and exergy and thermoeconomic analysis for thermal systems. He is a permanent member of Korean Academy of Science and Technology.

Reference

Jaekyoon Oh, Yungpil Yoo, Samsun Seung, Ho-Young Kwak. Laser-induced bubble formation on a micro gold particle levitated in water under ultrasonic field. Experimental Thermal and Fluid Science, volume 93 (2018) page 285–291.

Go To Experimental Thermal and Fluid Science

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