Fraunhofer Institute for Physical Measurement Techniques IPM
Precise measurement under challenging conditions
Solid-state electrolyte sensors are mainly used to determine the concentration of gases.
Their measuring principle is based upon the transport of ions in the solid electrolyte caused by electrochemical and electrocatalytic processes at the sensor surface. The result is a voltage in the sensor that is proportional to the concentration of the target gas, forming a stable sensor signal.
Solid-state electrolyte sensors are characterized by their fast response and high sensitivity. Their resistance to mechanical, thermal, and chemical influences makes them ideal for measurement even under harsh environmental conditions.
A well-known example for the use of solid-state electrolyte sensors is the lambda probe, which measures the oxygen content in the exhaust gas of combustion engines as part of the automotive catalytic converter.
Optimized sensors for selective gas detection
At Fraunhofer IPM, we optimize solid-state electrolyte sensors for selective gas detection. To this end, we research and vary the properties of the sensors with regard to their geometric design, electrical interconnection, the materials of the electrolyte and electrodes, and the operating temperature.
By selecting suitable electrode materials, we generate different adsorption properties and thus a dominant dependence of the sensor signal on the desired gas, for example, H2, CH4, or CO.
The expected logarithmic behavior of solid-state electrolyte sensors enables very high sensitivity and good resolution, especially in low concentration ranges – a few ppm. These properties allow the sensor element to be used for early detection of even the smallest gas leaks and for high-resolution measurement of hydrogen, for instance.
New areas of application thanks to miniaturization
The miniaturization of systems is playing an increasingly important role in our further development of solid-state electrolyte sensors. It makes a decisive contribution to reducing the consumption of expensive materials and further lowers the power requirements of heated sensors and their response times. This opens up completely new areas of application for the sensors, such as mobile hydrogen leak detection.