Toward the nanospring-based artificial olfactory system for trace-detection of flammable and explosive vapors

Chemical sensors were fabricated on the basis of novel nanomaterials – silica nanosprings. High chemical sensitivity was achieved by coating the silica nanosprings with ZnO using atomic layer deposition (ALD), followed by decorating with metal nanoparticles. The optimum operational conditions (T = 400 °C, ZnO grain size ∼15 nm) were obtained and investigated. The nanospring-based sensors demonstrated remarkable vapor sensing properties: well-defined spikes in conductance upon exposure to explosives (TNT, TATP) and flammable vapors (toluene, acetone, ethanol) were obtained for 0.1 ms exposure times at ppb level. Based on surface doping of ZnO with various metallic nanoparticles, a discrimination mechanism was developed and an integrated sensor-array for simultaneous real-time resistance scans was built. The integrated sensor response was tested using linear discriminant analysis (LDA). The distinguished electronic signatures of various chemical vapors were obtained at ppm level.