Selective Detection of NO and NO(2) with CNTs-Based Ionization Sensor Array

The accurate detection of NO(x) is an important issue, because nitrogen oxides are not only environmental pollutants, but also harm to human health. An array composed of two carbon nanotubes (CNTs)-based ionization sensors with different separations is proposed for NO and NO(2) selective detection. The experimental results indicate that the CNTs-based ionization sensor has an intrinsic, monotonically decreasing response to NO or NO(2). The sensor with 80 µm separations and 100 µm separations exhibited the highest sensitivity of −0.11 nA/ppm to 300 ppm NO and −0.49 nA /ppm to 70 ppm NO(2), respectively. Although the effect of the NO(2) concentration on the NO response is much stronger than that of NO on NO(2), the array of these two sensors still exhibits the ability to simultaneously detect the concentrations of NO and NO(2) in a gas mixture without component separation.