Download Manipulation of thin liquid films and nanoparticles with surface

Manipulation of thin liquid films and nanoparticles with surface charge patterns
Type: primarily experimental project, option for numerical calculations
Contact: Anton Darhuber (e-mail: a.a.darhuber)
We designed a setup that allows writing of arbitrary surface charge patterns onto electrically
insulating substrates. A droplet of water is attached to a metallic needle and dragged over the
surface with a computer-controlled xy-translation stage.
Photograph (left) and schematic (right) of a setup for writing arbitrary surface charge patterns
onto an electrically insulating substrate.
The non-uniform surface charge distribution induces electrical stresses in thin liquid films
that are deposited onto the substrate, which induces flow towards regions of higher surface
charge density. The objectives of the project are to study 1) the charge deposition process for
a number of different substrate materials, 2) the dynamics of the redistribution of a liquid film
that is spin-coated on top of the surface charges as well as 3) the preferred deposition of
suspended nanoparticles on the charged or the uncharged regions.
(Left) surface charge pattern written onto a plastic substrate. (Right) Photograph of film thickness
modulation induced in a ~ 5 micron thin liquid film.