Learning from Nature

Technical applications of biomimetic nanostructures

Optical components are an important part of many modern devices, ranging from miniature cameras to mobile phones and medical applications such as endoscopes to high-performance optical sensors of ever-decreasing size in industry and robotics.

Picture explanation: SEM image of nanoAR structures fabricated in fused silica. The average spacing (center to center of nanopillars) is 100 nm and height is 200 nm (image copy right MPI IS).

Problem statement

In all optical applications, the commonly occurring yet detrimental reflection of light is still a problem. These reflections make images appear darker, interfere with the optical path, produce "ghosting" and can even seriously damage devices in certain laser applications. In order to reduce these undesirable reflections, so-called anti-reflective coatings have generally been used up to now. These very thin layers of special materials are however only effective within very small wavelength ranges and also have a relatively low mechanical strength and durability.

Problem solving – learning from nature

Some insects have had the solution to this problem for millions of years. On the surface of a moth’s eyes for example, miniscule, conical nanostructures ensure an almost complete absence of reflection.

Based on this example, the Max Planck Institute for Intelligent Systems has developed a technique for the nanostructured anti-reflective coating of surfaces. Until now, the production of these coatings has been very expensive and time-consuming.

With the newly-developed nanoAR process, however, affordable production on a large scale has now become possible. In our research group, we continue to develop the commercial potential of this technology.

Picture explanation: SEM image of nanoAR structures fabricated in fused silica under ×20000 magnification. Insert: Zoom in of the same image with ×50000 magnification. These nanopillars are highly periodic over large surface area (image copy right MPI IS).
Transmittance nanoAR versus conventional coating

Picture explanation: Red curve: Transmittance of nanopillars in fused silica with spacing 100 nm and height 450 nm. The maximum is 99.8% at wavelength 700 nm. Dark dashed curve: Transmittance of multilayer broadband AR coating on the same substrate. The operation wavelength band is narrower and the maximal transmittance is lower than nanoAR strucutres (graph copy right MPI IS)
AOI nanoAR versus conventional coating

Picture explanation: The average transmittance and reflectance of the fused silica with 450 nm-sized nanopillars (blue triangle and black square) compared to a reference sample (pink triangle and red circle) measured at different wavelength between 380 to 1000 nm and with different angle of incidence (AOI) between 0 to 75° (5° steps are depicted, reflectance starts at 8°). The AOI range of nanopillars is 30° to 40° broader than that of a flat surface (graph copy right MPI IS)

Advantages of the procedure

nanoAR method Other methods
Efficient, cost-effective (15 min / side) Complex, time-intensive (hours)
Wide operating range (> 1500 nm) Limited operating range (10 to 300 nm)
High T and low R tunable (UV, VIS, NIR) Limited tunable range
For various optical materials For select few materials
Stable with a high temperature gradient Unstable with a high temperature gradient

Application possibilities with the nanoAR method

The nanoAR method offers many possibilities for improvement in various sectors and industries:

  • · Optical lenses or laser components
  • · Smartphones and other display devices
  • · Clean-energy devices
  • · Medical optical devices
  • · Ultra-sensitive detectors

Collaborations

Scientific

Prof. Dr. Robert Brunner, Ernst-Abbe Hochschule and Fraunhofer Institut IOF
Prof. Dr. Jan-Henning Dirks, Hochschule Bremen

Industrial

Leica Camera AG, within the NeoMAT Projekt

Information on research

The nanoAR technology was developed in the Departments of Prof. Dr. Joachim P. Spatz at the Max-Planck-Institute for Medical Research and the Max-Planck-Institute for Intelligent Systems within the nanoAR Research Group.

The nanoAR research is funded by the German Ministry of Education and Research.

Patents and patents pending.


Contact

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c/o kwhi GmbH
Goethestraße 2
89173 Lonsee
Germany

smartphone +49 (0)171 287 53 22
emailinfo@kwhi.de