Electrospun Nanofibre Based Chemical Sensor: Electrical Characterization

Abstract

Nanofibre-based gas sensors give the advantage of fast response times and high sensitivity due to the higher surface area to volume ratio compared to thin film sensors. This paper characterizes the DC and AC impedance of individual electrospun nanofibres fabricated from two different materials: (1) Polymer based polyaniline/polyethylene oxide (PANI/PEO) nanofibres and (2) metal oxide based nanofibres (TiO2). Impedance spectroscopy was used to examine the charge transport mechanism in the nanofibres. Single nanofibres and nanofibre mats were then exposed to different chemical environments and the resistance change was correlated to gas concentration. Applications for such biomedical and chemical sensors include the detection of volatile organic compounds, exposure to which can cause serious health effects.

Electrostatic fabrication or electrospinning is a simple way of fabricating nanofibres from a polymer solution [1]. PANI is a conductive polymer that is widely used for its simple reversible doping/dedoping chemistry, stable electrical conduction mechanism, and high environmental stability [2]. In conducting polymer chemiresistors, the electrical resistance of the polymer is modified due to adsorption of chemical species affecting the mobility of the charge carriers. The presence of electron donating gases reduces the charge carrier concentration, leading to a decrease in conductivity [3]. TiO2 is a semiconducting metal oxide and is widely used in sensing applications [4]. Adsorbed oxygen on the surface of the nanofibre will decrease the carrier concentration and mobility and therefore render the nanofibre less conductive. Any species interacting with the adsorbed oxygen will therefore cause a resistance change.