Fig. 43.

(a) Response of sensors coated with PAA/NaCl NFN membranes containing different concentrations of NaCl: 0 (green), 0.1 (blue), and 0.2 wt% (red), exposed to increasing TMA concentrations ranging from 1 to 100 ppm. The coating load was 3500 Hz for each sensor. The inset is the amplified image in the range of 0–2000 s. (b) Frequency shift versus TMA concentration (1–100 ppm) for three nanofibrous membranes coated QCM sensors. (c) Frequency shift of the PAA/NaCl (0.1 wt%) NFN membranes Δf_t/Δf_∞ coated sensor with a coating load of 3500 Hz versus 20 ppm of various VOCs. The inset shows the schematic of gas-sensing mechanism between PAA nano-nets and TMA. (d) The (Δf_t/Δf_∞ < 0.5) as a function of t^1/2/h when exposed to 1 ppm of TMA vapors for three nanofibrous membranes coated QCM sensors. The lines are linear fits to Fickian diffusion. Reprinted with permission from [31]. © 2011 Royal Society of Chemistry.