High sensitivity near-field opto-chemical sensors based on SnO2 particles layers

In this work, the surprising sensing performances of opto-chemical sensors based on SnO2 particles layers against chemical pollutants either in air and water environment, at room temperature, are reported. The Electrostatic Spray Pyrolysis (ESP) method has been used to deposit the sensing coatings upon the distal end of standard fibers. This technique allows the fabrication of SnO2 layers composed of micron and sub-micron dimensions able to locally modify the profile of the optical near-field collected in the close proximity of the fiber tip. Such layers morphology leads to strong surface interactions between sensing coatings, analyte molecules and the evanescent contribute of the field, resulting in an excellent sensors sensitivity against chemical pollutants, even at room temperature.