Abstract
This work investigates deposition patterns left by evaporating particle-laden droplets on heterogeneous surfaces with spatially varying wettability. Spatial differences in receding contact angles give rise to scalloped-shaped contact lines. During evaporation, the contact line recedes in one location and remains pinned in another. This non-uniform contact line recession results in particle self-assembly above areas where the contact line remains pinned, but not where it recedes. This behavior is fairly robust across a variety of particle sizes, concentrations, and device geometries. We hypothesize that particle self-assembly in these cases is due to the competition between particle diffusion and the evaporative-driven advective flow. Diffusion appears to be more pronounced in regions where the contact line recedes while advection appears to be more pronounced near the pinned portion of the contact line. As such, particles appear to diffuse away from receding areas and toward pinned areas where advection transports them to the contact line. The distribution of particle deposition above the pinned regions is influenced by the particle size and concentration of particles in the droplet. Similar to homogeneous surfaces, deposition is more prevalent at the pinned portion of the contact line for smaller particles and lower concentrations, and more uniformly distributed across the entire pinned region for larger particles and higher concentrations. A better understanding of this process may be beneficial in a wide variety of particle separation applications like printing, cell patterning, biosensing, and anti-icing.
Library of Congress Subject Headings
Fluid-structure interaction; Drops--Analysis; Particle dynamics analysis; Evaporation
Publication Date
12-14-2023
Document Type
Dissertation
Student Type
Graduate
Degree Name
Engineering (Ph.D.)
Department, Program, or Center
Engineering
College
Kate Gleason College of Engineering
Advisor
Michael Schertzer
Advisor/Committee Member
Blanca Lapizco-Encinas
Advisor/Committee Member
Kara Maki
Recommended Citation
Li, Xi, "Characterizing the Evaporating Droplets over Heterogeneous Wettability Surfaces" (2023). Thesis. Rochester Institute of Technology. Accessed from
https://repository.rit.edu/theses/11616
Campus
RIT – Main Campus
Plan Codes
ENGR-PHD
