This is the first time that solid-state electrolytes have been used as sensors, combining high thermal and mechanical stability with a small size, fast measurement response and high sensitivity for e.g. leak detection or for monitoring the lower explosive limit of fuel cells.
Modern production techniques have been applied to the development of a hydrogen sensor system, which is particularly suitable for measurements between 0 – 10 000 ppm H2. The working principle of the sensor system is so-called solid state electrolysis. Electrolysis is a technique applied in chemistry and manufacturing, where direct electric current (DC) is used to drive a chemical reaction that otherwise would not be spontaneous. Normally the electrolyte used in the reaction is fluid. However, in case of the Hydrogen Sensor, the electrolyte is a solid-state body, comprised of stabilized Zirconium Dioxide. This ceramic material provides a two-dimensional mesh structure and shows three special characteristics: high thermal stability, high mechanical stability, and high ion conductivity.
The material can be produced as a cubically stabilized ceramic, which first made it possible for solid-state electrolytes to be used as sensors. The stabilizing process, also called “doping”, produces an oxygen vacancy, over which free moving oxygen ions (O2-) can be transported at high temperatures. This oxygen ion transportation is the basis for the electric conductivity of the electrolyte. This allows Hydrogen (H2) measurements starting from even 1 ppm e.g. for leak detection or for monitoring the lower explosive limit of fuel cells.
To meet the high demands regarding quality and quantity, a multi-layer procedure is used which uses screen-printing. This innovative process combined with other thin film techniques is used in manufacturing the miniaturized sensors. This hybrid technique makes it possible to manufacture reproducible, reasonably priced sensor elements in large quantities. The multilayer sensors are printed on planar carrier substrates with the help of screen-printing. This technique allows the sensor geometry to be easily varied, including the order of the layers and the materials for producing different types of sensors. The sensors are manufactured under controlled clean room conditions in order to ensure highly pure material.
Innovations & Advantages
- High resolution down to 1 ppm
- Fast response
- Mechanically, chemically and thermally robust
- Small dimensions
- Wide range of applications
Current and Potential Domains of Application
The sensor is applicable for measurement and monitoring duties in a wide range of hydrogen applications.