Using a PEDOT:PSS modified electrode for detecting nitric oxide gas

PEDOT:PSS thick films, prepared by the drop-coated method, were used in this study for sensing nitric oxide (NO) gas. The thickness of PEDOT-PSS film was controlled by dropping different volumes of PEDOT-PSS solution to improve the response of PEDOT-PSS film. Due to its porous structure, the thicker the PEDOT-PSS film is, the higher the noticeable surface area. Thus, a larger response is found. However, since the concentration of NO gas used was low (10 ppm), the effect of the surface area was not noticeable when the thickness of the film was greater than 5 μm. In the range of 2.5–10 ppm NO, the relationship between the response of the PEDOT-PSS film and the NO concentration was linear. The limit of detection (S/N = 3), response time (t95), and recovery time (t95) were about 350 ppb, 527 s, and 1780 s, respectively. The response of PEDOT-PSS film to 10 ppm NO gas was dramatically affected by the presence of either O2 or CO. The standard deviation, with respect to the sensitivity of the NO gas sensor based on PEDOT:PSS film, was 2.2%. The sensitivity of the sensor remained at about 74.5% that of a fresh one.