H2 Pressure Senses
Hydrogen-compatible pressure sensors made of ceramic sensor bodies with highly sensitive sensor layers

The project is part of the BMWi programme ‘Innovations for the energy transition’ and deals with the development of hydrogen-compatible pressure sensors. With the help of ceramic sensor bodies and highly sensitive stretch-sensitive thin films, pressure sensors are to be developed that are ideally suited for applications with hydrogen, a key element of the energy transition.

The project is a tripartite network of a pressure sensor manufacturer, a ceramics developer and the research group Sensors and Thin Film Technology of the Saarland University of Applied Sciences under the direction of Prof. Schultes.

problem

Hydrogen is considered a promising candidate for the replacement of fossil fuels and is therefore one of the central elements for solving the energy transition.
For applications such as hydrogen-powered vehicles with fuel cells, it is imperative to determine the pressure of the compressed hydrogen gas. However, there are two fundamental problems with the pressure measurement of hydrogen: Hydrogen diffusion and hydrogen embrittlement.
The mobile hydrogen molecules can easily diffuse through conventional pressure sensors with metallic deformation bodies in contact with the media and cause embrittlement, which can lead to sensor failure. If the hydrogen reaches the sensor layer, the electrical measuring resistors can change and, as a result, a signal drift can occur. Therefore, non-brittle austenitic steels (e.g. 1.4404, 1.4435) are usually used and the sensor bodies are provided with diffusion barriers (e.g. gold layer). Nevertheless, a signal drift of the sensors can occur, especially at elevated temperatures.

objective

The combination of resistant ceramic deformation bodies with a very low permeation rate for hydrogen and highly sensitive thin films is intended to create reliable, fail-safe pressure sensors especially for hydrogen applications.

approach

Instead of steel, ceramic materials are to be used for the deformation bodies. Together with ceramic experts and a sensor manufacturer, deformation bodies are developed that on the one hand have low permeation rates for hydrogen and on the other hand have good mechanical properties, which is essential for use as a sensor body.
In the next step, the ceramic bodies are provided with strain-sensitive thin layers so that the strain of the deformation body can be converted into a pressure-proportional electrical signal. Highly sensitive sputtered layers with a thickness of only about 100 nm are used. The high strain sensitivity of the layers makes it possible to reduce the mechanical stresses in the ceramic and still achieve a sufficiently high sensor signal. In order to keep the susceptibility of the sensor layers to hydrogen as low as possible, the layers are examined separately and optimized for use with hydrogen. By means of ceramic-compatible connection technology and the connection of a sensor electronics, reliable and high-precision pressure sensors are created that are ideally suited for the medium hydrogen.

Project management: Dennis Wachter, M. Sc.; Maximilian Mathis, M. Sc.
Project management: Prof. Dr. Günter Schultes
Duration: 01.07.2020 – 30.09.2022
Funded by: BMWi

Final report
Category: Multimodal smart sensing

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