We demonstrated humidity sensing characteristics based on a suspended single tungsten nanowire. The nanowire is synthesized on batch-processed microelectrodes by focused ion beam-chemical vapor deposition (FIB-CVD) using tungsten hexacarbonyl [W(CO)6] as the precursor gas. Two different humidity sensing mechanisms, electrothermal sensing and chemical sensing, were demonstrated using as-deposited and annealed nanowires. When the relative humidity level was increased from 30% to 80%, the DC resistance of the as-deposited nanowire immediately showed 5.68% decrease by electrothermal sensing mechanism. Since the as-deposited nanowire is amorphous structure, no chemical sensing response was observed for the as-deposited nanowire case. On the contrary, the tungsten nanowire annealed at 700 C showed a 13.2% increase in its DC resistance by the chemical sensing mechanism when the relative humidity level was increased from 40% to 80%, revealing enhanced sensor responsiveness and improved linearity than the electrothermal sensing using as-deposited nanowire.
Bibliographical noteFunding Information:
This research was supported by the Converging Research Center Program through the Ministry of Science, ICT and Future Planning, Korea (2013K000388), the Pioneer Research Center Program through the National Research Foundation of Korea funded by the Ministry of Science, ICT & Future Planning (2010-0019313) and the Center for Integrated Smart Sensors funded by the Ministry of Science, ICT & Future Planning as Global Frontier Project (CISS-2011-0031870).
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Surfaces, Coatings and Films
- Metals and Alloys
- Electrical and Electronic Engineering
- Materials Chemistry