Effect of Aspect Ratio (Length:Diameter) on a Single Polypyrrole Nanowire FET Device
نویسندگان
چکیده
The effect of different aspect ratios (length to diameter ratio, L:D) on single polypyrrole (Ppy) nanowire based field effect transistor (FET) sensors for real time pH monitoring was studied. Ppy nanowires with diameters of ∼60, ∼80, and ∼200 nm were synthesized by using electrochemical deposition inside anodized aluminum oxide (AAO) template and were assembled using AC dielectrophoretic alignment followed by maskless anchoring on a pair of gold electrodes separated with different gap lengths. Microfabricated gold electrode patterns with gap size between 1 and 4 μm were developed by means of MEMS technique (photolithography), and used in a field effect transistor geometry with a pair of microfabricated gold contact electrodes serving as a source and a drain, and a platinum (Pt) mesh (anchored in a microfluidic channel) as a gate electrode. When the effects of different aspect ratios of the nanowire were compared, higher sensitivity was recorded for a higher aspect ratio. The sensitivity was further improved by modulating the gate potential. These FET sensors based on a single polypyrrole nanowire exhibited excellent and tunable sensitivity toward pH variations.
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