Improving sensing features of a nanocomposite PEDOT:PSS sensor for NO breath monitoring

Some attempts to improve sensing features of a previously investigated chemosensor for NO breath monitoring, based on a nanofibrous layer of titania coated by a very thin layer of PEDOT:PSS were reported here. The time necessary for sensor response, linked to a few seconds of duration of breath lung, was overcome by designing and implementing two measuring procedures allowing the gas to flow throughout the sensor for more time (at least 90 s): a fixed volume breath storage chamber collecting a portion of the exhaled air and a recirculation path where the sampling gas recirculated through the sensor until reaching a satisfactory response. Thus a serpentine coil shaped chamber with a total volume of about 100 cm3 was designed with the aid of finite element method (FEM) simulations and the whole measuring set-up (i.e. pump, Nafion® tubing, oxidizing cartridge and sensor chamber) was comprised in a loop layout. The adoption of these strategies resulted in a LOD of about 6 ppb assuming of working with an actual handheld diagnostic device. Specifically, when the sensor was exposed to NO concentrations between 5 ppb and 300 ppb (limited to 90 s of measurement), sensor responses resulted to be linear and clearly distinct from the noise, with an accuracy <3 ppb up to 50 ppb and <8 ppb for concentrations ranging between 50 ppb and 300 ppb.