The internet, innovative displays and sensory wound dressings

Prof Dr Patrick Görrn and the Chair of Large-Area Optoelectronics

What do today's Internet and future sensory wound dressings have in common? The Chair of Large-Area Optoelectronics at the University of Wuppertal, Prof Dr Patrick Görrn, provides answers to these and other questions.

When his little two-year-old daughter is already enthusiastically wiping over the photos on her mobile phone, the chair holder knows the fascination that light exerts on people.

Optics is the study of light. Optoelectronics deals with the question of how light can be generated, measured or converted into electrical energy in electronic components. This is how the digital camera in a mobile phone takes a picture. Light-emitting diodes (LEDs) generate light and a display uses this light to show the original image.

The display - like the solar cell - is an example of large-area optoelectronics. While other electronic components are becoming increasingly miniaturised, the focus of this discipline is on achieving optoelectronic functionality cost-effectively on large surfaces.

LEDs are replacing previous lighting sources

"Light generation with LEDs," explains the native of Brandenburg, "has now achieved an internal efficiency of almost one hundred per cent". Although there is still a need for development to extract this internally generated light as completely as possible from the component, LEDs are already far superior to earlier light sources as electronic components.

As microelectronic components, LEDs are pure point light sources. However, if waveguides are used that distribute their light over a surface and emit it homogeneously, the result is area lights, i.e. large-area components. These waveguides are not only a new trend in lighting technology, they are also used in the construction of displays. The light emitted over a large area is transmitted or absorbed by liquid crystals (LCD, Liquid Crystal Display). The pixels of the display are defined by this controlled absorption.

Wave Guide Displays (WAGUDI)

Absorption in liquid crystals converts light into heat. LCDs are therefore comparatively inefficient, even if they are now illuminated with LEDs, i.e. the best available light sources.

If the light could only be taken from the waveguide where it is actually needed, a display could be realised without reducing efficiency through absorption. This is exactly what the WAGUDI waveguide display is all about. In this invention by Görrn, a special waveguide is "detuned" by an electrical voltage. This causes light to be scattered out of the waveguide at a selectable location. The result is an actively switchable display. WAGUDI has since been patented by the university.

The origin of our internet age

While planar waveguides are becoming increasingly interesting for large-area applications, other waveguides - glass fibres - have long since become an integral part of our lives. "If you explain optoelectronics, you can't get past the Internet," explains the electrical engineer. "We transmit information via optical fibres and amplify it optically. Without optoelectronics, the internet age as we know it would not have been possible at all. Hardly any other field of research has developed so rapidly.

For Görrn, the advantage for the user is obvious. Take displays, for example: "Every display I buy is bigger than the old one, has a higher resolution, is more efficient and costs less." This is how he describes a technology that focuses on innovation from the outset, where the buyer constantly expects it to be better in terms of quality and performance data and also cheaper. The situation is similar with the ever faster Internet connection. He explains: "When I take out a new contract, I naturally want a higher data rate than in my old contract."

Soft electronics?

Electrical engineering has also become indispensable in the medical field. Will implants directly in the brain be possible at some point? Might it even be possible to quickly load a new foreign language via the body's own USB port? Görrn emphasises: "There is indeed a desire to equip components with electronic functionality and bring them into direct contact with the human body or organs." The engineer cites the example of a special wound dressing that is to be equipped with sensors. "We have co-developed concepts to create electronic functionality in very soft structures." The intelligent wound dressing, which contains a soft and air-permeable sensor system, could then be used by a doctor to read out the condition of a chronic wound, for example, without contact. This method would allow wound dressings to be used for longer. Sterility would be maintained during the testing of the wound.

The 39-year-old is working on numerous research projects with seven colleagues and several students. The father of two daughters works on an interdisciplinary basis with his colleague from Macromolecular Chemistry, Prof Dr Ullrich Scherf, among others. For the future, the first scientist from the University of Wuppertal to receive one of the prestigious ERC grants* would like to work more closely with Wuppertal companies.

Uwe Blass (interview from 10 January 2018)

* The ERC Starting Grants support promising young scientists at the beginning of an independent career.

Prof Dr Patrick Görrn studied electrical engineering at the TU Braunschweig. He completed his doctorate at the Institute for High Frequency Technology (IHF) there. From 2009 to 2011, he was a postdoctoral researcher at Princeton University. In April 2011, he was appointed junior professor at the Faculty of Electrical Engineering, Information Technology and Media Technology in Wuppertal, where he took over the Chair of Large Area Optoelectronics in 2014.