At sea and in high-performance electronics New sensor concepts thanks to integrated glass fiber optic cables

Integrated light guides in glass have the potential to significantly improve the measurement quality of sensors for research and industry. In the "3DGlassGuard" project, a consortium involving Fraunhofer IZM is working, among other things, on a sensor for measuring the density of seawater, which is intended to enable more uniform climate models. The researchers also aim to realize sensors for power electronics using novel optical 3D microstructures and AI design processes in glass.

Sensors are increasingly reaching their limits in electrical measurements, especially when used in sensitive environments such as large energy parks or underwater. The problem with current sensor concepts is power loss and cost-intensive manufacturing processes. A solution approach is offered by sensor concepts based on integrated optical fibers in glass. A large consortium of industry and research is working on this in the BMBF-funded project "3DGlassGuard". Three-dimensionally structured glass layers are to be integrated into the circuit board. These glass-core substrates enable new applications in sensing and data transmission.

The researchers from the Fraunhofer Institute for Reliability and Microintegration IZM, together with the other partners in the project, are developing novel sensor types that are interesting for industries such as energy, infrastructure, environmental and marine research. Traditional sensor solutions used fiber-based or electrical conductors. "3DGlassGuard" aims to change this with a glass layer that is three-dimensionally structured through ion exchange and selective laser etching (SLE) and directly integrated into the circuit board.

Applications for industry and research

The project is developing sensor concepts for two application scenarios. In cooperation with Siemens, experts are realizing an optical current sensor for power electronic applications, such as current measurements in high-power electronics. This new sensor is not built from a circuit of optical fibers, which typically require a lot of space on the circuit board and complex adjustments to function correctly, but from optical fibers integrated into a 3D glass layer on the circuit board. Additionally, the integrated glass layer bypasses previously occurring interactions because it is galvanically isolated and the optical fibers are enclosed in the glass. These optical fibers are characterized by low transmission losses and simultaneously allow the guiding of light with different wavelengths and states, such as a defined polarization. This makes it possible to measure and transmit much more information than by purely electrical means.

Another sensor is being developed in collaboration with Sea & Sun Technology for measuring the density of seawater. It uses the principle of an interferometer, which measures the superposition of light waves. Currently, density sensors measure the electrical conductivity of seawater, from which its density can be derived. However, this process relies on globally varying reference values. A more direct, purely optical measurement using the new sensor concept would enable significantly higher resolution and a standardization of the measurement results. This could, for example, allow for more uniform climate models to be created.

Currently, researchers are working on the implementation of demonstrators, which will then undergo functionality tests with the companies. A particular challenge is the miniaturization of the new sensor concepts to fit them on a circuit board. However, the planar form of glass offers more possibilities for integrating optical fibers and additional functionalities. In parallel with the development of the sensors, AI-supported simulation tools are being developed in collaboration with TU Berlin. These are intended to help reduce the size and increase the efficiency of individual optical components of the sensors, in ways that would not be possible by a human alone.