Acoustic and optical sensors incorporating carbon nanotubes for detection of organic solvents

We investigate the sensing properties of single-walled carbon nanotube (SWCNTs) films used as nanostructured materials for chemical sensors onto three types of transducers using different principles of operation. These are surface acoustic waves (SAWs), quartz crystal microbalance (QCM) and standard silica optical fiber (SOF) for detection of organic solvents, at room temperature. The sensing probes have been configured as a 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 (CdA) matrix was deposited by an LB technique onto SAW sensors. An LB multilayer of SWCNTs-onto-CdA buffer material was also deposited onto QCM and SOF sensors. Our experiments demonstrate that carbon nanotube acoustic and optical sensors are highly sensitive to a wide range of polar and non-polar organic solvents up to a sub-ppm detection limit.