Hydrophobic Surface Carrier


Key to using the electro-wetting effect for moving droplets is a super hydrophobic and well gliding surface. There are different coating materials on the market for electro-wetting such as Fluoropel, Teflon AF or Cytop. These are amorphousfluoropolymer that can be deposited by spin coating or by dipcoating. For the first experiments with the OpenDrop we just used Polyethylen (PE) kitchen foil (saran wrap) coated with Rain-X a commercially available rain repellent for wind shields. We stretched the foil on a frame of acrylic and applied the Rain-X by blob-coating. It’s important for the effect to work that the droplets slide easily on the surface and do not stick to it.

Later we developed more advanced solutions for devices with top cover and also found a simple solution using parafilm and silicon oil for the topless configurations. See here for different materials that were tested.

Electro-wetting on hydrophobic foil using only readily available materials, parafilm and silicon

Step by step description of the process by Udayan Umapathi:

Dual Layer Electro-wetting on hydrophobic foil

Detailed process on how to do a hydrophobic coating using FluoroPel PFC1601V from Cytonix and ETFE Foils from Nowofol :