Plasticised polymeric electrolytes: new extremely versatile receptor materials for gas sensors (VOC monitoring) and electronic noses (odour identification/discrimination)

A new class of receptor materials for gas sensors for volatile organic compounds (VOC) was developed: plasticised polymeric electrolytes (PPE). A PPE usually consists of three components: a polymer; a plasticiser; and an organic salt. In an extensive systematic study more than 500 compositions using seven polymers, eight plasticisers and four organic salts were tested in order to investigate the effect of individual components and their ratio on the gas sensing properties (selectivity, sensitivity, etc.) of the PPE. The operation of a PPE-based gas sensor is based on a variation of the bulk ionic conductivity of the receptor layer due to absorption of an ambient vapour. The specific conductance of the used PPE compositions is usually between 0.1 and 10 μS×cm −1 and it may vary more than 100 times in the dynamic range of the gas sensor, which stretches typically from low ppm up to some 10 000 ppm. The PPE-based gas sensors using miniaturised interdigitated transducers demonstrate a remarkable variety of their properties depending on the PPE composition. The performance of single sensors and sensor arrays was thoroughly studied.