The study of a carbon nanotube O2 sensor by field emission treatment

A novel O2 sensor was made from carbon nanotubes (CNTs) synthesized by a thermal chemical vapor deposition system. The resistance of such grown CNT thin film was measured in a vacuum chamber at various oxygen pressures and was found to exhibit a cyclic property according to the oxygen filling-pumping cycle. The sensitivity was very linear from 2.59% to 6.22%, corresponding to oxygen filling pressures from 6.665 × 10− 2 mbar to 1.066 mbar. Afterward, the CNT thin film underwent various field emission treatments, and the resistance measurement was repeated under the same condition.At an O2 pressure of 1.066 mbar, the sensitivity was 10.68%, 5.73%, and 4.38% with 1, 2, and 3 h of field emission treatment, respectively. It still retained good linearity after the field emission treatment. The Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) showed that the sensitivity was related to the ratio of ID/IG and O/C. A proper duration of field emission treatments could improve the performance of CNT oxygen sensors.