Technologies

We propose an optical technique for the fast check of the presence, on the exposed surfaces of persons and objects, of explosives and their precursors, or drugs, or in general materials which are not allowed in restricted environments: airports, courts, places of worship, etc. The technique yields bi-dimensional pictures, with exposure time of < 1 sec, reporting the target substances, and their locations and quantities. The technique already provided laboratory preliminary results, to be completed, and fully validated for sensitivity and selectivity.

The proposed technology takes advantages of the huge potentialities of the gellan gum microgels in the preservation of cultural heritage. Microgels are polymeric gels particles with the micro and nanoscale size, whose soft nature is due to the presence of the aqueous solvent inside the particle. For their small size, they can easily diffuse in the environment and penetrate in the porous structure of paper and wood to act as cleaner agent.

The proposed technology deals with the development of active SERS (Surface Enhanced Raman Scattering) substrates ad hoc designed for diagnostics of cultural heritage. The substrates are prepared starting from common commercial 'polishing film' sheets (lapping optical fibers) showing an intrinsic roughness (48- 1000 nm) that favors the SERS effect. A pattern of silver or gold nanoparticles are deposited on these films through Pulsed Laser Deposition (PLD).

The instrument which is under development is a non-conventional portable Raman spectrometer. Raman spectrometers provide the molecular composition of the material surfaces, essential for their identification. The instrument peculiarity relies in the simultaneous acquisition of Raman spectra at imaged position and at different micrometric distances (offset) from the laser illumination area.