Solid State Electronic Sensors for Detection of Carbon Dioxide.

Detection of carbon dioxide (CO) is very important for environmental, health, safety and space applications. We have studied novel multiwall carbon nanotubes (MWCNTs) and an iron oxide (FeO) nanocomposite based chemiresistive sensor for detection of CO at room temperature. The sensor has been miniaturized to a chip size (1 cm × 2 cm). Good sensing performance was observed with a wide detection range of CO concentrations (100-6000 ppm). Structural properties of the sensing materials were characterized using Field-Emission Scanning Electron Microscopy, Fourier-Transform Infrared and Raman spectroscopies. The greatly improved sensitivity of the composite materials to CO can be attributed to the formation of a depletion layer at the p-n junction in an MWCNT/iron oxide heterostructure, and new CO gas molecules adhere to the high surface area of MWCNTs due to the concentration gradient. The test results showed that the CO sensor possesses fast response, compact size, ultra-low power consumption, high sensitivity and wide dynamic detection range.