Statistical analysis of DNT detection using chemically functionalized microcantilever arrays

The need for miniaturized and sensitive sensors for explosives detection is increasing in areas such as security and demining. Micrometer sized cantilevers are often used for label-free detection, and have previously been reported to be able to detect explosives. However, only a few measurements from 1 to 2 cantilevers have been reported, without any information on repeatability and reliability of the presented data.

In explosive detection high reliability is needed and thus a statistical measurement approach needs to be developed and implemented. We have developed a DVD-based read-out system capable of generating large sets of cantilever data for vapor and liquid phase detection of 2,4-dinitrotoluene (DNT). Gold coated cantilevers are initially functionalized with tetraTTF-calix[4]pyrrole molecules, specifically designed to bind nitro-aromatic compounds.

The selective binding of DNT molecules on the chemically treated surfaces results in significant bending of the cantilevers and in a decrease of their resonant frequencies. We present averaged measurements obtained from up to 72 cantilevers being simultaneously exposed to the same sample. Compared to integrated reference cantilevers with non-selective coatings the tetraTTF-calix[4]pyrrole functionalized cantilevers reveal a uniform and reproducible behavior.