A novel highly sensitive palladium-based hydrogen sensor is being developed with two industrial partners in the BMBF project “H2MEMS”. The project is part of the HYPOS consortium as part of the “Twenty20 – Partnership for Innovation” funding initiative launched by the German Federal Ministry of Education and Research. The three partners are further developing the ideas of the previously successfully completed HYPROS project. Silicon-based MEMS structures are coated with palladium and can be manufactured using microsystems technology (Si technologies) methods. As a result, these sensors can be manufactured more cost-effectively and offer great potential for further miniaturization and reduction of energy consumption.
The CiS Research Institute, a proven specialist in the development of silicon-based pressure sensors, is developing and testing palladium-coated MEMS structures similar to Si MEMS pressure sensors in the project with its partners. Palladium has the highest absorptivity of all elements for hydrogen. At room temperature, it can bind 900 times its own volume. This leads to an increase in volume, which is to be used for a basic sensory element (MEMS device). If a palladium layer is applied to a passive material (membrane) of the basic element, considerable mechanical stresses are created due to the volume increases. The magnitude of the mechanical stresses is a measure of the hydrogen content in the palladium. By means of a highly sensitive piezoresistive measuring bridge, these mechanical stresses can be evaluated metrologically. The signal is a measure of the hydrogen content in the sample gas. With the new sensor, H2 concentrations in the ppm range and up to 100 vol% can be measured without any doubt.
In a first step, different basic structures are selected at the CiS Research Institute and coated with palladium by a project partner. Extensive FEM simulations refine the material selection for the sensor. Classical semiconductor technologies for manufacturing are adapted to the specific requirements by the CiS Research Institute and technological platforms are developed. Important parameters are a large measuring range, the avoidance of cross-sensitivities, a high long-term stability as well as a fast response.
The coating, the measurement setup, the electronics and the simulation test under real conditions are carried out by the project partners Union Instruments GmbH and Materion GmbH.
The project contributes to making natural gas networks more economical for energy storage and energy transformation.
The project on which this report is based was funded by the German Federal Ministry of Education and Research under funding code 03ZZ0757B.