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Charge transfer from ammonia physisorbed on nanotubes
Keith Bradley1, Jean-Christophe P Gabriel, Mikhail Briman
1Nanomix Inc, Emeryville, California 94608, USA.
Physical Review Letters
|December 20, 2003
Summary
We developed nanotube field-effect transistors for detecting ammonia in liquids. This chemical sensor measures ammonia by observing shifts in electrical current, revealing charge transfer at the molecular level.
Area of Science:
- Nanotechnology
- Chemical Sensing
- Materials Science
Background:
- Nanotube field-effect transistors (NTFETs) offer high surface-to-volume ratios for sensitive detection.
- Chemical sensing in conducting liquid environments presents unique challenges for electronic devices.
Purpose of the Study:
- To investigate the efficacy of NTFETs for detecting ammonia in a conducting liquid.
- To quantify the charge transfer mechanism underlying ammonia detection by NTFETs.
Main Methods:
- Utilized NTFET devices in a conducting liquid medium.
- Monitored the shift in gate voltage dependence of source-drain current upon ammonia exposure.
- Analyzed concentration-dependent responses to determine charge transfer per molecule.
Main Results:
- NTFETs successfully detected ammonia through measurable shifts in electrical characteristics.
- The observed shifts were attributed to charge transfer from adsorbed ammonia molecules.
- Quantified charge transfer as low as 40 electrons and determined 0.04 electron per ammonia molecule.
Conclusions:
- NTFETs are effective chemical sensors for ammonia in conductive liquids.
- The study quantifies molecular-level charge transfer, demonstrating high sensitivity.
- This work advances the application of nanotube-based sensors in liquid environments.