Speciation of energetic materials on a microcantilever using surface reduction.

Although microcantilevers have been used to detect explosives with extremely high sensitivity using variations in adsorption-induced bending and resonance frequency, obtaining selectivity remains a challenge. Reversible chemoselectivity at ambient temperatures based on receptor-based detection provides only limited selectivity due to the generality of chemical interactions. The oxygen imbalance in secondary explosives presents a means to achieve receptor-free speciation of explosives using surface reduction of adsorbed molecules. We demonstrate highly selective and real-time detection of Trinitrotoluene (TNT) using a copper oxide-coated cantilever with a surface reduction approach. Not only can this technique exclusively differentiate explosives from nonexplosives, but also it has the potential to specify individual explosives such as TNT, pentaerythritol tetranitrate (PETN), and RDX. This technique together with receptor-based detection techniques provides a multimodal approach for achieving very high selectivity.