Technology Offers

Permanent air layer under water reduces friction and prevents fouling & corrosion


Within a project of the Baden-Württemberg Stiftung a novel surface technology has been developed that can hold gas molecules between a surface and surrounding liquids. Such a material could be extremely useful in shipbuilding rendering toxic anti-fouling coatings obsolete and simultanously reducing frictional resistance between vessel and seawater, thus saving fuel.


Surfaces that can hold a gas layer under water are of great technical interest. The application potential ranges from friction reduction and antifouling coating in shipbuilding, chemical engineering and pipeline construction, use in the textile industry as a new type of thermal insulation to sensor technology and many more.


In order to prevent fouling of a ship's hull below the water surface, either biocide-containing paints or coatings that are particularly easy to clean are currently used in shipbuilding. However, none of the solutions can guarantee a permanent protection of an area under water in an environmentally friendly way, especially if the surface is not moved on a regularly base.


Funded by the Baden-Württemberg Stiftung gGmbH, researchers at the Karlsruhe Institute of Technology led by Prof Dr Thomas Schimmel have developed a novel surface technology that can hold gas molecules between the surface and surrounding liquid over a long period of time. Like their natural model, the leaves of the floating fern Salvinia molesta, the ingenious coatings have structures that are highly hydrophobic near the surface but hydrophilic at the interface to the liquid. This creates areas that are not wetted by the liquid and in which gas is held by the surface tension of the surrounding medium. The configuration of the structures can be adapted to different pressure conditions.
At the same time, the layer acts as a corrosion inhibitor because, for example, the metal of a ship's hull is no longer in direct contact with seawater. Another advantage of the new surface technology is the reduction of the friction energy to be overcome while driving. The reduction of friction between ship and water through the air layer alone is conservatively estimated to be at least 10 %. In addition, savings are achieved by completely avoiding fouling; this also effectively prevents introduction of alien species.

The biological model of technology: Water drop on leaf hair of salvinia molesta (source: KIT).
The biological model of technology: Water drop on leaf hair of salvinia molesta (source: KIT).


  • Permanent air retention under water
  • Environmentally friendly, biocide-free antifouling & corrosion protection for moving & stationary objects
  • Retrofitting coating possible (as film)
  • Numerous other areas of application: Liquid transport, thermal insulation, reaction vessels ...


Surface material for:

  • anti-fouling coating
  • friction reduced transport of liquids
  • novel type of thermal insulation
  • novel reaction vessels
Dr. Frank Schlotter
Ettlinger Straße 25
76137 Karlsruhe | Germany
Phone +49 721-79004-0
schlotter(at) |
Development Status
Validation / TRL4
Patent Situation
EP 2822704 B1 granted,
DE, FR, GB, CH, BE, IT, ES, NL, FI, GR, DK, NO, SE, TR, PT & IE validated
EP 20203559.8 pending
BR 11 2014 0218102 pending
CA 2,866,082 granted
CN ZL 2013 80 023 387.6 granted
CN 106984510 B granted
IN 312933 granted
JP 6270745 granted
JP 6715821 granted
KR 10-2028621 granted
KR 102210224 granted
KR 10-235670 granted
US 9,630,373 B3 granted
US 10,625,833 granted
US 16/815,696 pending

DE 102018003141 B4 granted
EP 19720 061.1 pending
CN 201980026256.0 pending
CA 3,097,076 pending
US 16/982,321 pending
KR pending
Reference ID
12/006TLB & 18/027TLB