Carbon Nanotube Thin Films Functionalized via Loading of Au Nanoclusters for Flexible Gas Sensors Devices

Carbon nanotubes (CNTs) have been demonstrated to be one of the most interesting materials for gas sensing. This paper applies a simple method for the direct transfer of high-density CNTs from a SiO2/Si substrate to a flexible substrate for carbon dioxide (CO2), ammonia (NH3), and isopropyl alcohol gas sensing at room temperature. The flexible gas sensor exhibited high sensitivities of 4.8%, 5.4%, and 5.2% at room temperature for ambient CO2, NH3, and isopropyl alcohol gas concentrations of 800 ppm, respectively. In addition, the gas response of the CNT-based chemiresistor is attributed to p-type conductivity in the Au-modified semiconducting CNTs. Very good repeatability of the sensor response to gas concentration is demonstrated, representing a major step toward the low-cost large-scale production of this class of device.