TY - JOUR
T1 - Development of automated angle-scanning, high-speed surface plasmon resonance imaging and SPRi visualization for the study of dropwise condensation
AU - Ahangar, Shahab Bayani
AU - Konduru, Vinaykumar
AU - Allen, Jeffrey S.
AU - Miljkovic, Nenad
AU - Lee, Seong Hyuk
AU - Choi, Chang Kyoung
N1 - Funding Information:
This research was partially sponsored by the National Research Foundation of Korea (NRF) grant that was funded by the Korea government (MSIP) (No. 2017R1A2B2006943, SHL). The authors acknowledge Dr. Fei Long from Michigan Technological University for his assistance on surface roughness characterization by AFM.
Funding Information:
This research was partially sponsored by the National Research Foundation of Korea (NRF) grant that was funded by the Korea government (MSIP) (No. 2017R1A2B2006943, SHL). The authors acknowledge Dr. Fei Long from Michigan Technological University for his assistance on surface roughness characterization by AFM. d Thickness (nm) k 0 Proportionally constant (molecules/cm 2 s) k a Adsorption coefficient k al Adsorption coefficient at the liquid–vapor interface k as Adsorption coefficient at the solid–vapor interface K B Boltzmann coefficient [1.38E–23 (J/K)] n Refractive index P Pressure (Pa) R Gas constant [8.314 (J/mol K)] r a Rate of adsorption (molecules/cm 2 s) r d Rate of desorption (molecules/cm 2 s) R SPR SPR reflectance T Temperature (K) w Energy per mole required to evaporate adsorbed molecules (J/mole) w s Energy per mole required to evaporate adsorbed molecules at the solid–vapor interface (J/mole) w l Energy per mole required to evaporate adsorbed molecules at the liquid–vapor interface (J/mole) α \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\alpha$$\end{document} Incident angle (°) ε \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\varepsilon$$\end{document} Relative permittivity θ \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\theta$$\end{document} Contact angle (°) Λ \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\varLambda$$\end{document} Surface coverage, fraction of surface covered with adsorbed molecules (m 2 /m 2 ) λ \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\lambda$$\end{document} Illumination light wavelength (nm) ω \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\omega$$\end{document} Uncertainty
Publisher Copyright:
© 2019, The Author(s).
PY - 2020/1/1
Y1 - 2020/1/1
N2 - Abstract: This paper describes the fabrication and testing of a novel angle-scanning surface plasmon resonance imaging (SPRi) instrument. The combination of two stationary mirrors and two angle-controlled mirrors provides high accuracy (up to 10−3°) and high-speed angular probing. This instrument minimizes the angle-dependent image artifact that arises due to beam walk, which is the biggest challenge for the use of SPRi with angular modulation (AM). In the work described in this paper, two linear stages were employed to minimize the image artifact by adjusting the location of the angle-controlled mirrors and the camera. The SPRi instrument was used to visualize coalescence during dropwise condensation. The results show that the effect of the environment’s temperature on reflectance was less than 1% when the incident angle was carefully chosen for SPRi with intensity modulation (IM). This means that condensation visualization can be carried out at ambient temperatures, without the need for a Peltier stage or a thermally controlled condensing surface. The concept of pixel neighboring was employed to assess the probability of noise and the standard error of thin film measurement. Experimental analyses during dropwise condensation show (1) the presence of a thin film with thickness of one monolayer, and (2) surface coverage of 0.71 m2/m2 by the thin film in the area between the droplets. In addition, analyses showed the existence of a dry area at the part of the substrate exposed by coalescence to ambient air. The results of this work undermine the validity of the film rupture theory as the dropwise condensation mechanism. Graphic abstract: [Figure not available: see fulltext.].
AB - Abstract: This paper describes the fabrication and testing of a novel angle-scanning surface plasmon resonance imaging (SPRi) instrument. The combination of two stationary mirrors and two angle-controlled mirrors provides high accuracy (up to 10−3°) and high-speed angular probing. This instrument minimizes the angle-dependent image artifact that arises due to beam walk, which is the biggest challenge for the use of SPRi with angular modulation (AM). In the work described in this paper, two linear stages were employed to minimize the image artifact by adjusting the location of the angle-controlled mirrors and the camera. The SPRi instrument was used to visualize coalescence during dropwise condensation. The results show that the effect of the environment’s temperature on reflectance was less than 1% when the incident angle was carefully chosen for SPRi with intensity modulation (IM). This means that condensation visualization can be carried out at ambient temperatures, without the need for a Peltier stage or a thermally controlled condensing surface. The concept of pixel neighboring was employed to assess the probability of noise and the standard error of thin film measurement. Experimental analyses during dropwise condensation show (1) the presence of a thin film with thickness of one monolayer, and (2) surface coverage of 0.71 m2/m2 by the thin film in the area between the droplets. In addition, analyses showed the existence of a dry area at the part of the substrate exposed by coalescence to ambient air. The results of this work undermine the validity of the film rupture theory as the dropwise condensation mechanism. Graphic abstract: [Figure not available: see fulltext.].
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U2 - 10.1007/s00348-019-2844-9
DO - 10.1007/s00348-019-2844-9
M3 - Article
AN - SCOPUS:85076022290
VL - 61
JO - Experiments in Fluids
JF - Experiments in Fluids
SN - 0723-4864
IS - 1
M1 - 12
ER -