Silicon Nanowire Detects Explosives

Arrays of functionalized silicon nanowires can serve as selective, ultrasensitive explosives detectors, according to researchers at Israel’s Tel Aviv University. In addition to using the devices in security applications, the nanowires could serve as sensors for soil and water analyses, Yoni Engel, Fernando Patolsky, and coworkers report. The researchers fashioned field-effect-transistor detectors from silicon nanowires coated with a monolayer of 3-aminopropyltriethoxysilane and used the devices, which can distinguish between compounds with and without nitro groups, to detect 2,4,6-trinitrotoluene (TNT) at subfemtomolar concentrations (Angew. Chem. Int. Ed. 2010, 49, 6830). Some of the test devices reached unprecedented attomolar levels, they note, thereby outperforming trained sniffer dogs and all other types of explosives detectors. The team adds that the portable detectors can be used on solution-phase and air samples without preconcentration and extensive sample preparation, and they gave reproducible results throughout a weeklong run involving some 100 tests. The researchers explain that the molecules bind tightly to the nanowires through an acid-base pairing interaction between TNT and amino groups on the sensor surface.