title: Characterization of the wettability of thin nanostructured films in the presence of evaporation.
abstract: Vapor chambers using conventional porous membrane wicks offer limited heat transfer rates for a given thickness. This limitation can be addressed through wick nanostructuring, which promises high capillary pressures and precise control of the local porosity. This work develops a measurement technique for the wettability of nanostructured wicks based on optical imaging. Feasibility is demonstrated on a hydrophilic silicon nanowire array (SiNW) synthesized using the Vapor-Liquid-Solid (VLS) growth mechanism followed by surface plasma treatment. The wettability is determined by comparing the time-dependent liquid interface rise with a model that accounts for capillary, viscous, and gravitational forces and for evaporation. This model is demonstrated to be useful in extracting internal contact angle from thin ( approximately 10microm) porous films.
authors.affiliation: Department of Mechanical Engineering, Stanford University, 440 Escondido Mall, Bldg 530, Room 224, Stanford, CA 94305, USA. rogacs@stanford.edu
authors.forename: Anita
authors.initials: A
authors.lastname: Rogacs
authors.forename: Julie E
authors.initials: JE
authors.lastname: Steinbrenner
authors.forename: Jeremy A
authors.initials: JA
authors.lastname: Rowlette
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Weisse
authors.forename: Xiaolin L
authors.initials: XL
authors.lastname: Zheng
authors.forename: Kenneth E
authors.initials: KE
authors.lastname: Goodson