Multilayer systems with a variety of optical and sensory functions are already commercially viable in the field of microelectronics, and this will soon extend to the packaging sector and consumer electronics too. The flexibility, rate of production and sophisticated coating technologies are enabling functional layer systems to be scaled up and mass produced.
The “Application of multi-functional layers” group at Fraunhofer IPA is concerned with light‑emitting layers. These are applied on flat and uneven surfaces using the full spectrum of printing and coating processes. The current focus is on luminous layers, specifically on the effect of electroluminescence.
In the field of sensors, Fraunhofer IPA have already developed transparent pressure and touch sensors on flexible substrate materials. This is in addition to the manufacture of stretchable sensors, which have been produced with the help of coating processes. The clever arrangement and geometry of the functional layers also allows for detection of other environmental factors, such as humidity, temperature and UV radiation. To this end, a variety of materials – conductive, semi-conductive and insulating – are used. These are often spherical particles of metals (e.g. silver, copper, aluminum and gold) or carbons. In addition, fibers such as silver, boron nitride and carbon nanotubes can be manufactured. Functional layers have also been manufactured from electrically conductive or insulating polymers.
Yet the variety of materials used in production also poses challenges: it is important to select the appropriate material carefully on the basis of the intended use, which can have an impact on the adhesion between the individual layers as well as the opacity of the entire layer system. The long‑term stability and weather resistance of sensors are further specifications which need to be taken into account when developing robust sensor fields. We have the capability of measuring all of these parameters in our laboratories, which enables us to define our sensors more comprehensively.
In addition to the production of optical multilayer systems, we have set ourselves the goal of developing innovative sensor systems with flexible volumes, while also developing manufacturing processes further. If you are also active in a similar field, or are looking to branch out, we would be pleased to explore potential development projects with you.