Wafer-Scale Fabrication of Single Polypyrrole Nanoribbon-Based Ammonia Sensor

Abstract

Ultra-long (>1 cm) polypyrrole (PPy) nanoribbons were batch-synthesized to predetermined locations on 4 inch Si wafers and flexible polyimide film with controlled thicknesses and widths via modified Lithographically Patterned Nanowire Electrodeposition (LPNE), which combines top-down “photolithography” and bottom-up “electrodeposition”. The excessive lengths and lithographic approach enable subsequent patterning of electrodes for direct device fabrication. Electrical transport properties were investigated by temperature-dependent measurements, and back-gated FET measurements were performed to study the properties with respect to the conductivity of PPy nanoribbons. To demonstrate the utility of this approach these nanoribbon devices were interrogated as gas sensors in a conductometric fashion. They displayed excellent sensitivity toward ammonia vapor with a detection limit in the sub ppm. The sensitivity toward ammonia vapor was tuned by the conductivity of the PPy nanoribbons via chemical de/doping.

The electrochemical growth of conducting polymer “nanowires”

“…These methods include forming the deposit under a small overhang created at the edge of a metal line electrode [1], polymerisation in a small drop on the end of a sharp tip which is moved to create the wire [2], polymerisation using a scanned pipette, and polymerisation with the electrolyte confined to a groove between the electrodes [3]. Direct electrochemical growth of single wires between two electrodes, without any particular fabrication other than the preparation of the electrodes, has also been proposed, following the extensive work on electrochemical growth of metal wires [4] and on dielectrophoretic assembly into wires of both metal and semiconductor particles [5][6][7][8][9][10].…”

Bulk synthesis, optimization, and characterization of highly dispersible polypyrrole nanoparticles toward protein separation using nanocomposite membranes

“…Polypyrrole (PPy) is the one of most investigated conducting polymers, owing to its facile synthesis, good conductivity, redox properties, long-term environmental stability and biocompatibility as polymer in vivo [9], and has shown promising applications including sensors [10], actuators [11], photovoltaic/solar cells [12,13], electromagnetic interference shielding [14], and corrosion protection [15]. In addition, PPy nanocomposites have been shown biodegradability and biocompatibility, which are potentially useful in drug delivery and tissue engineering [5,16].…”

Porous silica coated spherical microresonator for vapor phase sensing of ammonia at a sub-ppm level

“…Increasing the concentration of ammonia in air causes severe adverse effects in the human respiratory system, eyes and skin. Over the past decade, several techniques for the detection of NH3have been reported based on measurements of electrical current in nano structured metal oxides [3], conducting polymers [4], carbon nanotubes [5] and nano structured graphene [6].Optical fiber based sensors have some unique advantages over their electrical analogues such as remote and real time monitoring, immunity to various sources of disturbance such as electromagnetic interference, radioactivity, and explosive environments. Amongst the optical fiber techniques, sensors based on the whispering gallery modes (WGMs) in spherical microresonators have found many applications in the fields of molecular adsorption [7],refractive index [8],temperature [8] and gas sensing [9] due to their ultra-high quality factors, low absorption losses and inexpensive fabrication.…”