Toluene Detection in Aqueous Phase by Optical Fiber Sensors Integrated with Single-Walled Carbon Nanotubes

Recent preliminary studies have demonstrated the feasibility of using Single-Walled Carbon Nanotubes (SWCNTs) as sensitive coatings of optical fiber sensors for the detection of chemical traces in water at room temperature. A lowfinesse extrinsic Fabry-Perot configuration was adopted as sensing scheme and Langmuir-Blodgett thin SWCNT films have been integrated to form the sensing optical cavity. This contribution reports on the improvement of the performance of such SWCNTs-based chemo-optic transducers based on a proper choice of the number of carbon nanotube monolayers. The results here shown reveal a strong enhancement in term of sensor sensitivity of more than one order of magnitude, combined with a significant reduction of the response times. The achieved sub-ppm resolution, the response rapidity, and the complete and fast recovery of the initial output signal corresponding to the condition of uncontaminated water reveal the potentiality of the improved version of the sensor to be applied for water monitoring applications.