Table 2.

Average responses R ± their standard error of the four sensors to T1, T2, T3 and T4 of Figure 3.

	$\mathbf{ST}25+1\mathit{\%}\mathbf{Au}$	${\mathbf{SmFeO}}_3$	$\mathbf{STN}$	$\mathbf{TiTaV}$
${\overline{R}}_{T1}$	1.49 ± 0.04	1.22 ± 0.02	1.64 ± 0.05	1.19 ± 0.02
${\overline{R}}_{T2}$	1.85 ± 0.12	1.29 ± 0.03	1.92 ± 0.10	1.30 ± 0.06
${\overline{R}}_{T3}$	1.54 ± 0.07	1.24 ± 0.01	1.64 ± 0.06	1.18 ± 0.02
${\overline{R}}_{T4}$	1.26 ± 0.02	1.14 ± 0.01	1.31 ± 0.02	1.09 ± 0.01