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Table 1: Comparison of the coefficient of variation, D (%) for three MWCNT-based gas sensors: (i) CNTs unfunctionalized, (ii) CNTs modified with Au loading of 5 nm, (iii) CNTs modified with Au loading of 10 nm, toward five gas exposures of individual gas of 1 and 10 ppm NO2, 100 and 1000 ppm NH3. The sensor temperature for all sensors is 200°C. The thickness of MWCNTs is about 250–300 nm.

Gas concentration Coefficient of variation, D (%) Sensor CNTs Sensor CNTs_Au-5 m Sensor CNTs_Au-10 m 1 ppm NO2 3.4 3.1 2.9 10 ppm NO2 14.1 1.2 3.0 100 ppm NH3 5.1 2.9 3.5 1000 ppm NH3 13.1 5.0 11.2