Multi-wall carbon nanotube gas sensors modified with amino-group to detect low concentration of formaldehyde

Gas sensors with multi-wall carbon nanotubes (MWCNTs) modified with amino-groups on interdigitated electrodes (IDE) were fabricated to detect low concentration of formaldehyde at room temperature. Effects of content of amino groups on sensing responses against various interfering circumstances and low concentration of formaldehyde were investigated. The sensor behaved high relative resistance changes to formaldehyde and lower response to interfering gases such as acetone, carbon dioxide, ammonia, toluene and ethanol. When the concentration of formaldehyde was 20 ppb, the relative resistance changes of the sensor modified with 18.19% amino-group reached 1.73%. The sensor displayed high chemical selectivity, fast response and good reproducibility to low concentration of formaldehyde, which was attributed to the properties of MWNTs and the interaction between the surface of MWCNTs and amino-group.