title: Microdroplet deposition under a liquid medium.
abstract: An experimental and numerical study of the factors affecting the reproducibility of microdroplet depositions performed under a liquid medium is presented. In the deposition procedure, sample solution is dispensed from the end of a capillary by the aid of a pressure pulse onto a substrate with pillar-shaped sample anchors. The deposition was modeled using the convective Cahn-Hilliard equation coupled with the Navier-Stokes equations with added surface tension and gravity forces. To avoid a severe time-step restriction imposed by the fourth-order Cahn-Hilliard equation, a semi-implicit scheme was developed. An axisymmetric model was used, and an adaptive finite element method was implemented. In both the experimental and numerical study it was shown that the deposited volume mainly depends on the capillary-substrate distance and the anchor surface wettability. A critical equilibrium contact angle has been identified below which reproducible depositions are facilitated.
authors.affiliation: Linné Flow Centre, Department of Mechanics, Royal Institute of Technology, SE-100 44 Stockholm, Sweden. walter@mech.kth.se
authors.forename: Walter
authors.initials: W
authors.lastname: Villanueva
authors.forename: Johan
authors.initials: J
authors.lastname: Sjödahl
authors.forename: Mårten
authors.initials: M
authors.lastname: Stjernström
authors.forename: Johan
authors.initials: J
authors.lastname: Roeraade
authors.forename: Gustav
authors.initials: G
authors.lastname: Amberg
mesh_terms: D008722:Methods; D009716:Numerical Analysis, Computer-Assisted; D010316:Particle Size; D015203:Reproducibility of Results; D012996:Solutions; D013500:Surface Tension; D017155:Wettability
chemical_list: D012996:Solutions