Fabrication of polypyrrole–phenylalanine nano-films with NH3 gas sensitivity

Stretchable and High-performance Sensor films Based on Nanocomposite of Polypyrrole/SWCNT/Silver Nanowire

“…However, the sensor films fabricated on the basis of the composite of functionalized PPy NP with SWCNTs-Ag NW hybrid networks were more sensitive to NH3 as compared with a sensor film comprising only PPy-PA-complexed NPs. This result is explained by the fact that SWCNTs-Ag NW hybrid networks as conductors extend the movement path of electrons and the electron movement becomes more active (the sensing mechanism of NH3, in the case of sensor films comprising PPy NP-complexed with PA, is explained in a previous paper [27]. Selectivity is another important parameter for a gas sensor in practical use.…”

“…Functionalized conductive PPy particles coupled with phenylalanine (PA), as an ammonia sensing material, were prepared according to our previous paper [27]. First, PVP (average molecular weight 1,300,000) was dissolved in water.…”

“…The flow rate of each gas was controlled using a mass flow controller and the humidity measurement was monitored using a humidity sensor installed in the gas flow path. Figure 1, PPy-PA-complexed NPs of functionalized PPy as the sensing material, comprising PA-bound PPy NPs, have been reported to be potentially applicable as good chemical sensors [27]. Basically, they are connected via a layer-to-layer hybrid to the SWCNT-Ag NW hybrid network conductors.…”

“…With this characteristic, PPy-PA NPs can exhibit sensitivity to specific chemical species following the redox process, for example, ammonia and these NPs can demonstrate excellent sensitivity via enhanced interaction between the PPy-PA NPs and analytes. In particular, when a functional structural material (here, PA) with a carboxylic group and an amino group symmetric to each other, as shown in the chemical structure of Figure 3, was electrically coupled to the electro-conductive PPy main chain, the positive charges of an amine group (NH 3 + region of PA) were sensitive to NH 3 [27].…”

“…Recently, strain sensors based on a nanocomposite of an Ag NWs network embedded between two layers of a polydimethylsiloxane (PDMS) elastomer has been reported to exhibit high stretchability up to 70% with strong piezoresistivity [4]. In addition, conducting polymers such as polypyrrole and polyaniline and their metal oxide nanocomposites have been reported to demonstrate considerable potential as an efficient chemical gas [24][25][26][27][28] or pH-responding materials [29,30] owing to their unique electrical, optical and mechanical transduction mechanism [31,32]. Our group [27] has also reported that the sensor films comprising polypyrrole nanoparticles (PPy NPs) complexed with phenylalanine (PA) sensitively react to ammonia gas and exhibit significantly improved reproducibility and reversibility upon gas exposure.…”