Properties of single OFET sensors without a receptor layer. (a) Dynamic sensor response to NO2 pulses at 100, 200, 500, 800, 1000 ppb concentration in dry (black) and humid air at 40% (red) and 95% (blue) relative humidity. (b) Corresponding response curves. (c,d) Response curves of the sensors for target analytes: NH3, H2S, Et-SH and NO2 in dry (c) and humid air at 95% RH (d). Mean values are presented with the standard errors.