From Sensors to Low‐cost Instruments to Networks: Semiconducting Oxides as Gas‐Sensitive Resistors

Low Cost Sensor Networks: How Do We Know the Data Are Reliable?

“…Sensors based on semiconducting oxides as gas-sensitive resistors have been much investigated for application in environmental measurement. Their characteristics have been much-studied and are well-understood 30, 31 . As for electrochemical cells, the issue of cross-interference and particularly the effect of water vapour pressure is important.…”

“…Sensors based on semiconducting oxides as gas-sensitive resistors have been thoroughly investigated for application in environmental measurement. Their characteristics have been well-studied and are well-understood. , As for electrochemical cells, the issue of cross-interference and particularly the effect of water vapor pressure is important. There is one particular example where such sensors have proven excellent: for environmental measurement of ozone. ,,, The key is the extremely large resistance change induced in heated WO 3 by trace ozone, much larger than the effect of any other trace gas in the environment with the possible exception of H 2 S, and the use of flow and temperature oscillation to cancel the effects of water vapor and continually reset the sensor and determine the zero. ,, This method represents a significant improvement over the more usual method of operation at constant temperature, which requires auxiliary measurement and compensation for the effects of variable water vapor pressure .…”

“…Their characteristics have been well-studied and are well-understood. 33,34 As for electrochemical cells, the issue of cross-interference and particularly the effect of water vapor pressure is important. There is one particular example where such sensors have proven excellent: for environmental measurement of ozone.…”