Abstract
More and more metal oxide semiconductor (MOS) gas sensors with digital interfaces are entering the market for indoor air quality (IAQ) monitoring. These sensors are intended to measure volatile organic compounds (VOCs) in indoor air, an important air quality factor. However, their standard operating mode often does not make full use of their true capabilities. More sophisticated operation modes, extensive calibration and advanced data evaluation can significantly improve VOC measurements and, furthermore, achieve selective measurements of single gases or at least types of VOCs. This study provides an overview of the potential and limits of MOS gas sensors for IAQ monitoring using temperature cycled operation (TCO), calibration with randomized exposure and data-based models trained with advanced machine learning. After lab calibration, a commercial digital gas sensor with four different gas-sensitive layers was tested in the field over several weeks. In addition to monitoring normal ambient air, release tests were performed with compounds that were included in the lab calibration, but also with additional VOCs. The tests were accompanied by different analytical systems (GC-MS with Tenax sampling, mobile GC-PID and GC-RCP). The results show quantitative agreement between analytical systems and the MOS gas sensor system. The study shows that MOS sensors are highly suitable for determining the overall VOC concentrations with high temporal resolution and, with some restrictions, also for selective measurements of individual components.
Highlights
Air pollution is one of the main environmental concerns in Europe and worldwide with outside and indoor air contributing to the overall burden of disease according to the EU project Healthvent [1]
As humans emit a cocktail of volatile organic compounds (VOCs) [4,5,6], and this is mainly responsible for poor air quality in indoor situations, a CO2 measurement is often referred to as indirect VOC measurement based on the studies of Pettenkofer [7]
We present a study on selective VOC measurements with metal oxide semiconductor (MOS) sensors and their stability in a real-world scenario
Summary
Air pollution is one of the main environmental concerns in Europe and worldwide with outside and indoor air contributing to the overall burden of disease according to the EU project Healthvent [1]. As humans emit a cocktail of VOCs [4,5,6], and this is mainly responsible for poor air quality in indoor situations, a CO2 measurement is often referred to as indirect VOC measurement based on the studies of Pettenkofer [7]. This approach neglects other VOC sources such as furniture and building materials as well as those coming from human activities like cleaning or cooking [8]. Chemical sensors can change their chemical properties during operation due to irreversible reactions, so drift is often reported [13]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
