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Zeolite membranes for highly selective formaldehyde sensors

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Güntner Andreas, Abegg Sebastian, Wegner Karsten, Pratsinis Sotiris,
Project Integrated system for in operando characterization and development of portable breath analyzers
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Original article (peer-reviewed)

Journal Sensors and Actuators B: Chemical
Volume (Issue) 257
Page(s) 916 - 923
Title of proceedings Sensors and Actuators B: Chemical


A major challenge in gas sensing (e.g. breath analysis or indoor air quality monitoring) is the accurate detection of trace-level pollutants in complex mixtures. While modern chemical gas sensors can be extremely compact, inexpensive and highly sensitive, their success is still limited by selectivity though. Here, we combine sensors with highly selective zeolite membranes pre-separating gas mixtures. Zeolites - broadly applied in catalysis and gas separation - effectively separate molecules based on kinetic diameter, sorption and diffusion characteristics. Therefore, zeolite membranes are suitable filters for gas sensors removing undesired species from mixtures like exhaled breath. As proof-of-concept, a zeolite MFI/Al2O3 membrane is placed upstream a highly sensitive but weakly selective Pd-doped SnO2 sensor. Their combination exhibits exceptional selectivity (>100) for formaldehyde down to 30 ppb at 90% relative humidity, outperforming state-of-the-art detectors by more than an order of magnitude. This novel concept is readily extendable to other tracers, as manifold combinations of widely tunable microporous membranes and gas sensor types can be realized in the modular sensing device. This could enable a new class of highly sensitive and selective portable breath detectors or compact indoor air monitors.