Acoustic and optical VOCs sensors incorporating carbon nanotubes.

The authors investigate the sensing properties of single-walled carbon nanotubes (SWCNTs) films, which are used as nanostructured materials for chem. sensors onto three types of transducers using different principles of operation as surface acoustic waves (SAWs), quartz-crystal microbalance (QCM), and a std. silica optical fiber (SOF) for detection of volatile org. compds. at a room temp. The sensing probes have been configured as 315- and 433-MHz SAW two-port resonator-based oscillator, 10-MHz QCM resonator, and SOF light-reflectometry-based system at a wavelength of 1310 nm. A nanocomposite film of SWCNTs embedded in a cadmium-arachidate matrix was deposited by Langmuir-Blodgett (LB) technique onto the SAW sensors. An LB multilayer of SWCNTs-onto-CdA buffer material was also deposited onto the QCM and SOF sensors. The expts. demonstrate that carbon-nanotubes acoustic and optical sensors are highly sensitive to a wide range of polar and nonpolar org. solvents up to a sub-ppm detection limit at a room temp.