Owing to their sensitive chemical-to-electrical transducer capabilities and compatibility with deviee miniaturization and low operation temperature, single-walled carbon nanotube field-effect transistor (SWCNT-FET) represents an attractive platform to provide solutions in the gas sensing field. In this work, SWCNT-FETs were fabricated and their performances for detecting low NO2 concentrations were evaluated. Outstanding deviees response was obtained, which was shown to follow a 2 power law dependence between the response and the NOz concentration in the range of 100 ppb up to 10 ppm. Such ultra-high response is attributed to an enhancement of the Schottky barrier modulation triggered by the specifie deviee configuration. The deviee configuration is based on individual semiconducting SWCNTs directly connecting the interdigitated Source-Drain electrodes. To the best of our knowledge, the results reported here correspond to the most sensitive deviee among the deviees based on non-functionalized carbon materials and operational at low temperatures. Furthermore, the obtained results are supported by a deep SWCNT characterization, and the changes in Schottky barrier's height induced by the,presence of gas molecules are estimated and discussed. Overall, the present reported results provide useful information for establishing a robust process for the fabrication of the next generation of CNT based gas-sensing devices.