New sensor concepts in the '3DGlassGuard' project

Sensors are increasingly reaching their limits when it comes to electrical measurements - especially when they are used in sensitive environments such as large energy parks or underwater. The problem with current sensor concepts is power losses and cost-intensive manufacturing processes. Sensor concepts based on optical fibers integrated into glass offer a solution. A large consortium from industry and research is working on this in the BMBF-funded '3DGlassGuard' project. The aim is to integrate three-dimensionally structured glass layers into the printed circuit board, as these glass core substrates enable new applications in sensor technology and data transmission.

In the project, researchers from the Fraunhofer Institute for Reliability and Microintegration IZM are working with other partners to develop new types of sensors that are of interest to sectors such as energy, infrastructure, environmental and marine research. Conventional sensor solutions to date use fiber-based or electrical conductors. '3DGlassGuard' aims to change this with the help of a glass layer structured three-dimensionally by ion exchange and selective laser etching (SLE) and integrated directly into the circuit board.

Applications for industry and research

The project is developing sensor concepts for two application scenarios. In cooperation with Siemens, the experts are realizing an optical current sensor for power electronic applications, such as current measurements in high-power electronics. This new sensor is not, as usual, made up of a circuit of optical fibers, which on the one hand requires a lot of space on the circuit board and on the other hand a complex adjustment in order to function correctly, but of optical fibers that are integrated in a 3D glass layer on the circuit board. In addition, the integrated glass layer avoids the interactions that previously occurred, as it is galvanically insulated and the optical waveguides are enclosed in the glass. These optical waveguides are characterized by low conduction losses and at the same time allow the guidance of light with different wavelengths and states, such as a defined polarization. This allows much more information to be measured and transmitted than by purely electrical means.

Another sensor is being set up together with Sea & Sun Technology to measure the density of seawater. It uses the principle of the 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 is based on different reference values worldwide. A more direct, purely optical measurement using the new sensor concept would enable significantly higher resolution and standardization of the measurement results. This could be used, for example, to create more uniform climate models.
The researchers are currently working on implementing the demonstrators in order to then subject them to functionality tests with the companies. One particular challenge here is the miniaturization of the new sensor concepts in order to accommodate them on a printed circuit board. Due to its planar shape, however, the material glass offers more possibilities for integrating the optical fibers and other functionalities.

Parallel to the development of the sensors, AI-supported simulation tools are currently being developed in collaboration with TU Berlin. These should help to miniaturize individual optical components of the sensors and make them more efficient in a way that would not be possible by humans alone.

The '3DGlassGuard' project runs from May 15, 2024 to May 14, 2027 and is funded with a total of 4.6 million euros. Of this, 69.3% comes from funds from the Federal Ministry of Education and Research from the Quantum Systems funding program. The project involves Siemens as project coordinator, Fraunhofer IZM, Contag, LightFab, Sea & Sun Technology, the Technical University of Berlin and Schott as an associated partner.