Gas sensors

Determining the oxygen content in gas mixtures is important for several applications like combustion engines, medical systems for respiratory gas monitoring and various industrial processes. By appropriately choosing measurement principle, sensor design and operating parameters, oxygen sensors can be adapted to various applications. Fraunhofer IKTS has recently developed a limiting-current type oxygen sensor based on a ceramic solid electrolyte, which features a self-diagnosis functionality.

Amperometric oxygen measurement offers some distinct advantages over other measuring principles. First of all, operation of limiting-current type oxygen sensors does not require a reference gas. The theoretical limiting current can easily be calculated, allowing a facile sensor calibration and self-diagnosis using ambient air. In contrast to the logarithmic signal dependence of potentiometric oxygen sensors, the linear response of limiting-current type sensors permits the use of a larger measuring range.

Development results

A limiting-current type oxygen sensor has been successfully miniaturized by IKTS to a size of 3.5 x 4.0 x 0.5 mm³ and its performance proven for oxygen measurement in respiratory analysis. The sensor components are manufactured by thick film technology (screen printing) and assembled using a high-temperature glass solder. The sensor features excellent response behaviour in the concentration range 10-25 vol% O₂, which is relevant for respiratory analysis.

Services offered

• Customization of sensor geometry, measuring range and operating parameters
• Sensor characterization and simulation to derive calibration data
• Sensor packaging and integration via ceramic joining technology
• Supply of sensor prototypes
• Development and transfer of sensor manufacturing technologies for industrialization