Volatile alcoholic compounds fibre optic nanosensor

A fibre optic sensor for detection of some volatile organic compounds (VOCs) is presented. This device is based on a new vapochromic material of formula [Au₂Ag₂(C₆F₅)₄(C₆H₅N)₂], presented in the form of bright red powders. This material changes its optical properties as colour or refractive index when exposed to some organic vapours, recovering its original state when vapours get disappeared. The sensor head consists of a nanometer-scale Fizeau interferometer doped with the vapochromic material, built onto a cleaved end of a multimode fibre optic pigtail by using the electrostatic self-assembly method (ESA). The fibre optic sensor is used in a reflection scheme, so the other extreme of the optical fibre pigtail is connected to an optical coupler, completing the set-up with an optical source that generates an interrogating signal and an optical detector to register the intensity modulated reflected measure. The response of the sensor has been characterized taking measures of its absorbance spectra and the intensity modulated reflected signal at 850 nm for different alcohols. Changes up to 3 dB in the reflected optical power were registered.