Fraunhofer Institute for Material and Beam Technology IWS
Fraunhofer Institute for Material and Beam Technology IWS

Surface functionalization with DLIP

High magnification image of a DLIP textured surface under the scanning electron microscope.
© Fraunhofer IWS
High magnification image of a DLIP textured surface under the scanning electron microscope.

Direct laser interference patterning has developed into a flexible and industry-oriented tool for producing targeted surface topographies. The technology with the abbreviation “DLIP“, short for “Direct Laser Interference Patterning“, plays out its particular strength in scalability while maintaining the same structure resolution. To make this possible, the scientists are developing technical solutions, process parameters and specific functionalities that enable users to find exactly the solutions they need.

DLIP can be used to process all materials that absorb light, i.e. metals, ceramics and plastics, as well as transparent polymers and glass. No additional material is introduced, nor is material removed as in machining processes. No filler material is required, the structures produced have the same mechanical properties as the base material, and the process step of layer adhesion during surface finishing is eliminated.

Applications

DLIP-textured steel stamps with decorative effect.
© Erich Utsch AG
DLIP-textured steel stamps with decorative effect.
Direct Laser Interference Patterning (DLIP) can be used to generate complex, meandering surface structures in the micrometer and submicrometer range that can prevent or greatly reduce ice adhesion.
© Fraunhofer IWS
Direct Laser Interference Patterning (DLIP) can be used to generate complex, meandering surface structures in the micrometer and submicrometer range that can prevent or greatly reduce ice adhesion.
DLIP-textured polycarbonate with decorative effect.
© Fraunhofer IWS
DLIP-textured polycarbonate with decorative effect.

Microstructured tools for the production of functionalized surfaces

  • Embossing tools (stamps) which produce holographic decorations by means of hot embossing processes (application: decoration and product protection)
  • Molding tools which produce polymer films with selective fluid-influencing properties by UV replication (Lab-on-Chip (LoC) systems)
     

Functionalized part/component surfaces

  • Interference pattern on cell components improves adhesion (increased reaction area in current-conducting films in batteries)
  • Microstructure generates anti-icing effect on aircraft wings
  • Hierarchical surface topographies on implants improve biocompatibility (growth of bone tissue and body compatibility)
  • DLIP technology enables complex component geometries such as endoprostheses, den-tal implants, hip or knee joints to be equipped with functional topographies
  • Structured medical devices with antibacterial surfaces realized by a “pincushion“ structure
     

Reproduction of biomimetic structures 

One research focus in the working group is dedicated to biomimetics, whereby structures and functions of living organisms are imitated.  In this context, the surface of the diatom, the lotus plant, the rose flower, the springtail and the sandfish have already been reproduced. 

  • Lotus effect: Hydrophobic or hydrophilic surfaces
  • Springtail: Antibacterial surfaces
  • Sandfish: Friction-reducing surfaces
     

Light Management

  • Topographic microstructuring can increase the absorption or emission of the device (OPVs and OLEDs) by diffraction effect and light scattering.
  • Increase in efficiency of PET-based OPVs by 37 % possible through hexagonal oriented microstructuring
  • Suitable DLIP system can be integrated into production chain for manufacturing organic solar cells or OLEDs and used for processing polymers and/or transparent conductive oxides (TCO)