Abstract
In this paper, the surprising sensing performance of fiber-optic near-field
chemical sensors, based on wavelength scale tin dioxide particle layers, against
chemical pollutants in air environment at room temperature are reported. The
layers were deposited upon the distal end of standard single-mode optical
fibers by means of the very simple, versatile, and low-cost electrostatic
spray pyrolysis technique. The morphologic and optical features of the deposited
layers were characterized by means of a complex scanning probe system constituted
by simultaneous atomic force microscope (AFM) and near-field scanning optical
microscope (NSOM). Particle layers composed by tin dioxide grains, with wavelength
and subwavelength dimensions, are very promising because they are able to
significantly modify the optical near-field profile emerging from the film
surface. As matter of fact, a local enhancement of the evanescent wave contribute
occurs leading to a strong sensitivity to surface effects induced by the analyte
interaction. Here, for the first time to our best knowledge, experimental
results on the sensing capability of the proposed chemical probes in air environment
are reported. Also, a preliminary study on the effects of the processing stage
and the post processing thermal annealing on the film morphology and near-field
behavior are presented.
© 2008 IEEE
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