Sensor systems

Metal oxide sensor for air quality measurement in rooms
© Fraunhofer IBP/Bernd Müller
Metal oxide sensor for air quality measurement in rooms.

Volatile organic compounds (VOCs) can be measured using physico-chemical detectors and sensors. Depending on the exactness, precision and specificity of the measurement method required to detect the gaseous compounds, different measurement principles are used. The following aspects are therefore determined before selecting a sensor system:

  • Nature of the gas or its chemical structure
  • Cross-correlations to other VOCs
  • Sensitivity and selectivity with regard to the compound to be measured
  • Application-specific limit and threshold values, measurement and calibration intervals
  • Power consumption, design, robustness and dimensions
  • If necessary, coupling with other detection principles
  • Controlling and readout mode of the input values
  • Stability under specific climatic conditions (temperature ranges, stability under varying degrees of humidity, air pressure influences)
  • Price and market availability

We have extensive practical experience in optimizing gas sensor systems coupled with chemical analysis. The various aspects of sensor technology (sensitivity, selectivity and cross-correlations, calibration capacities and behavior in different environmental conditions) can be significantly improved by choosing the right detection systems, optimizing them and programming them in a targeted manner. Depending on the task at hand, tests are conducted in the real environment (field studies) or on pilot plants in the laboratory under defined conditions (e.g. emission test chambers, laboratory fermenters) and gas test benches.

We focus on qualifying metal oxide semiconductors, so-called MOX gas sensors By selecting specific ceramics and sensor surfaces, as well as targeted control systems, signal values can be  assigned to discrete VOC emission values in a time-resolved and event-controlled manner. For this purpose, we have developed a method for calibrating MOX gas sensors (see Patent No. WO 2018/206385 A1): Calibration method, its application and device for carrying out the procedure).

Industrial projects

  • Sensors for detecting VOCs in the air inside aircraft
  • Sensor systems for detecting microbially-induced VOCs (MVOC sensors, mold sensors)
  • Controls for sensors to measure human emissions indoors
  • Demand ventilation in non-residential buildings