Nebulization of water/glycerol droplets generated by ZnO/Si surface acoustic wave devices

Guo, Yuanjun, Dennison, Andrew, Li, Yifan, Luo, Jikui, Zu, Xiao-Tao, Mackay, Logan, Langridge-Smith, Pat, Walton, Anthony and Fu, Yong Qing (2015) Nebulization of water/glycerol droplets generated by ZnO/Si surface acoustic wave devices. Microfluidics and Nanofluidics, 19 (2). pp. 273-282. ISSN 1613-4982

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Abstract

Efficient nebulization of liquid sessile droplets (water and water/glycerol mixtures) was investigated using standing waves generated using ZnO/Si surface acoustic wave (SAW) devices under different RF powers, frequencies and liquid viscosity (varied glycol concentrations in water). At such high RF powers, there are strong competitions between vertical jetting and nebulization. At lower SAW frequencies of 12.3 and 23.37 MHz, significant capillary waves and large satellite droplets were generated before nebulization could be observed. At frequencies between 23.37 and 37.2 MHz, spreading, displacement or occasionally jetting of the parent sessile droplet was frequently observed before a significant nebulization occurred. When the SAW frequencies were increased from 44.44 to 63.3 MHz, the minimum RF power to initiate droplet nebulization was found to increase significantly, and jetting of the parent droplet before nebulization became significant, although the average size of the nebulized particles and ejected satellite droplets appeared to decrease with an increase in frequency. With the increase of glycerol concentration in the test sessile droplets (or increase in liquid viscosity), nebulization became difficult due to the increased SAW damping rate inside the liquid. Acoustic heating effects were characterized to be insignificant and did not show apparent contributions to the nebulization process due to silicon substrate’s natural effect as an effective heat sink and the employment of a metallic holder beneath the ZnO/Si SAW device substrates.

Item Type:	Article
Additional Information:	Published online ahead of print.
Subjects:	F200 Materials Science F300 Physics H600 Electronic and Electrical Engineering
Department:	Faculties > Engineering and Environment > Mechanical and Construction Engineering
Depositing User:	Yifan Li
Date Deposited:	26 Feb 2015 11:38
Last Modified:	12 Oct 2019 22:53
URI:	http://nrl.northumbria.ac.uk/id/eprint/21252

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