Lehrinhalte
1) Basics and definitions
Sensors in nature and technology. “Artificial sensors”: why, what for, application areas. Sensor manufactures.
Definitions: sensor, physical sensor, chemical sensor, biosensor, gas sensor.
Principle of construction: receptor and transducer.
Performance characteristics (response, signal, sensitivity, calibration curve, drift, reproducibility, cross-sensitivity).
Gas concentrations (µg/m3, ppt, ppb, ppm, vol. %, % r.h).
Regulations and norms for pollutants in the EU, Germany, USA and other countries (OELs, TRKs, MAKs, AGW, TLV, PELs).
2) Principles of gas detection and classification of sensors
Fundamental properties of gases (molecules) and gas mixtures: molecular structure, thermal conductivity, diffusitivity, acid-base properties, redox ability, and the types of interaction with solid-state materials.
Classification of sensors on the basis of: (i) target gases, (ii) materials, and (iii) transduction principles.
3) Calorimetric, thermal conductivity and thermochemical sensors. Pellistors,
Principle of operation. Construction. Receptor and transducer materials.
Detection of flammable gases. LEL and UEL. Hydrogen detection. Methane detection. Examples of commercial sensors. Applications examples: coalmines, sewers, fuel cells. Limitations.
4) Optical (non-dispersive IR) sensors
Principle of operation. Construction. Receptor and transducer materials.
Detectable gases. Detection of CO2 and hydrocarbons. Examples of commercial sensors. Applications examples. HVAC applications. Limitations.
5) Electrical sensors
Principle of operation. Construction. Receptor and transducer materials: semiconducting oxides (SnO2) and nitrides (GaN), metals (Pd), conducting polymers, phthalocyanines, carbon nanotubes, graphene, nanowires and nanocomposites. Detectable gases. Detection of toxic gases. Oxygen detection with high-temperature conductors (SrTiO3). Examples of commercial sensors. Taguchi (TGS) sensors. Microplatforms. Applications examples: climate controls in cars, fire detection, gas alarms. Limitations.
6) Electrochemical sensors
Principle of operation. Potentiometric and amperometric (limiting current sensors). Mixed potential sensors. Construction. Receptor and transducer materials. Ionic and mixed conductors. Detectable gases. Detection of oxygen, NOx, CO2 and toxic gases. Examples of commercial sensors. Applications examples: lambda-sonde. Limitations.
7) Mass-sensitive sensors
Principle of operation. Construction. Receptor and transducer materials.
QMBs, SAWs and BAWs. Piezoelectric transducers. Thickness shear mode resonators. Quartz crystal microbalance (QMB, QCM). Surface and bulk acoustic wave sensors. Detection of VOCs.
8) Sensor selection
Sensor calibration. Measurement set-up. In situ and in operando characterization of sensor performance. Sensor development. Industrial perspective. Selection of sensors for applications in the fields of energy conversion and environmental protection.
