Characterization of inexpensive metal oxide sensor performance for trace methane detection

Abstract

Abstract. Methane, a major contributor to climate change, is emitted by a variety of natural and anthropogenic sources. Commercially available lab-grade instruments for sensing trace methane are expensive, and previous efforts to develop inexpensive, field-deployable trace methane sensors have had mixed results. Industrial and commercial metal oxide (MOx) methane sensors, which are intended for leak detection and safety monitoring, can potentially be repurposed and adapted for low-concentration sensing. As an initial step towards developing a low-cost sensing system, we characterize the performance of five off-the-shelf MOx sensors for 2–10 ppm methane detection in a laboratory setting (Figaro Engineering TGS2600, TGS2602, TGS2611-C00, TGS2611-E00, and Henan Hanwei Electronics MQ4). We identify TGS2611-C00, TGS2611-E00, and MQ4 as promising for trace methane sensing but show that variations in ambient humidity and temperature pose a challenge for the sensors in this application.

Determining methane mole fraction at a landfill site using the Figaro Taguchi gas sensor 2611-C00 and wind direction measurements

“…This is contrary to the conclusions of others, who have overlooked or dismissed the utility of the TGS 2611-C00 to measure [CH 4 ]. 19,31 The TGS 2611-C00 has no lter leading to improved CH 4 sensitivity compared to the TGS 2611-E00, thus making the TGS 2611-C00 a suitable option for this landll emission source.…”

“…In addition, although the TGS 2602 could not be used due to our inability to derive a R 0 baseline (see Section 4.3), it may be exploited in more complex [CH 4 ] reconstruction models in future to identify the presence of species causing crosssensitivities with other TGS units. 19,50 In our [CH 4 ] reconstruction approach, a large accumulated dataset was required for a dynamic R 0 baseline t. As 8 000 background-assigned resistance values were used to yield each A value, A (and hence [CH 4 ]) could not be derived from the ends of each dataset.…”

“…30,32,[36][37][38] Alternatively, the TGS 2611 is more CH 4 -selective with two varieties: the TGS 2611-E00 has a lter to improve CH 4 -selectivity, 39 whereas TGS 2611-C00 has no lter, meaning that the latter offers heightened sensitivity and a faster response, 40 at the expense of CH 4 selectivity. 19 Many previous TGS 2611-E00 studies have attempted to measure [CH 4 ] by devising various algorithms based on TGS resistance and environmental measurements. 31,34,[41][42][43] On the other hand, the TGS 2611-C00 has featured in fewer CH 4 studies but has delivered promising results, with [CH 4 ] exhibiting a clear correlation against TGS resistance.…”

“…17 With suitable calibration and testing, the low cost of SMO sensors may negate their nominally low precision and low sensitivity. 18,19…”

“…46 The TGS 2602 has nevertheless been used extensively in combination with other low-cost sensors to help to account for cross-sensitivities. 19,47–50…”