VOC detection using an all polymer flexural plate wave sensor

We have developed an all-polymer, micro-inkjet printed, flexural plate wave (FPW) sensor for toluene vapor detection. The sensor consists of a piezoelectric polyvinylidene fluoride (PVDF) substrate with conductive polyethylenedioxythiophene polystyrene sulfonate (PEDOT:PSS) interdigitated transducers (IDTs) and a polymer sensing layer coating for selective absorption of a targeted analyte. Sensor performance is investigated by exposing polyvinyl acetate (PVAc) and polystyrene (PS) sensing layers to varying concentrations of toluene vapor. The resulting frequency shift, due to mass loading, expansion and softening of the sensing layers, is compared with predictions using a semi empirical model. In this work, Flory-Huggins solution theory is used to predict the mechanical response of the sensing layers to solvent vapor concentrations.