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Functional Surfaces


    Fundamental understanding of bubble dynamics on various surfaces is essential to predict the phase change heat transfer performance and design bubble-driven microfluidic devices. In this study, we present very different bubble dynamics on a hydrophobic surface. This is the first quantitative study of single bubble dynamics on a hydrophobic surface having a contact angle greater than 100º. Fundamental understanding of bubble dynamics on heated hydrophobic surfaces will help to develop chemically patterned surfaces with enhanced boiling heat transfer and novel phase-change based micro-actuators and energy harvesters.

Unique bubble dynamics on a hydrophobic surface
    The bubble on the Teflon-coated wafer has about a three times larger departure diameter and 60 times longer growth period than one on the bare silicon wafer.
    On the hydrophobic surface, the bubble departs from the surface after a short necking period and leaves behind a small residual bubble nucleus on the surface, which then grows in the next cycle. As a result, no waiting period is observed.

Hydrophobic surface
Hydrophilic surface

UCLA Department of Mechanical and Aerospace Engineering, Last update: January 31st, 2008