Smart nitrate-selective electrochemical sensors with electrospun nanofibers modified microelectrode

This paper presents a highly sensitive dedicated sensor that selectively measures nitrate ions. Nitrate-selective electrode of the three-electrode electrochemical sensor is formed by modifying the working electrode of the sensor with a novel nanofibrous mat made of conductive polypyrrole nanofibers. The nanofibers are formed by electrospinning technique. By doping the polypyrrole nanofibers with nitrate ions during an electrochemical polymerization process, numerous nanopores complimentary to the size of the target ions are created in the surface of the nanofibers, thus forming nitrate selective trapping sites. In addition, the porous structure of the nanofibers provides a large surface area of interacting with the analyte. This leads to high sensitivity of the sensor at the level of 1-2 nA per μM. The design, fabrication, and characterization of this new sensor are presented. The results are also discussed.