GS7.4 - Selective Formaldehyde Detection at low ppb Level with Microporous Membranes and SnO2 Sensors
- 17th International Meeting on Chemical Sensors - IMCS 2018
2018-07-15 - 2018-07-19
- Gas Sensors 7 - Systems
- S. Abegg, A. Güntner, K. Wegner, S. Pratsinis - Particle Technology Laboratory, ETH Zürich, Zurich (Switzerland)
- 278 - 279
A major challenge in gas sensing (e.g. air quality and breath analysis) is the selective detection of trace-level pollutants. While many gas sensors exhibit sufficient lower detection limit down to ppb, they lack selectivity. Here, we present a novel concept that combines (1) a membrane taking over the selectivity task by pre-separating the gas mixture with (2) a chemoresistive gas sensor detecting the analyte. The membrane is decoupled from the sensors to allow individual fabrication and independent operation. It consists of a zeolitic molecular sieve featuring adjustable separation properties to match the analyte. As proof-of-concept, a compact zeolite MFI/Al2O3 membrane is placed before a nonspecific Pd-doped SnO2 sensor. In fact, this system exhibits excellent selectivity (even in gas mixtures) to carcinogenic formaldehyde over ethanol, ammonia, acetone and isoprene (all > 100) at 50% relative humidity, superior to existing sensors. This novel concept can be extended to other tracers and it could facilitate a new class of selective and portable gas detectors.