An ultra-sensitive piezoresistive polymer nano-composite microcantilever sensor electronic nose platform for explosive vapor detection

In the present paper, we demonstrate a compact, nonoptical, and inexpensive polymer nano-composite microcantilever sensor platform for the detection of 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-triazine (RDX) and pentaerythritol tetranitrate (PETN) vapors at room temperature. In order to achieve sufficient selectivity, the piezoresistive polymer nano-composite microcantilevers coated with gold surfaces are modified with self-assembled monolayers (SAM) of 4-mercaptobenzoic acid (4-MBA), 6-mercaptonicotonic acid (6-MNA) and 2-mercaptonicotonic acid (2-MNA). The SAMs formation is confirmed by FTIR and contact angle measurements. The ultrahigh sensitive piezoresistive polymer nano-composite microcantilever provides detection sensitivities in the below parts-per-trillion level within few seconds of exposure under ambient conditions. Maximum bending of the microcantilever is achieved within 20 s with response and recovery time of ∼3 s and 4 s, respectively. The cross selectivity of 4-MBA and 6-MNA coated microcantilevers is confirmed by investigating exposure to different organic compounds. We also demonstrate that the polymer nano-composite microcantilever is ideally suited for “electronic nose” applications. Further, the ultra-high sensitivity and low cost of polymer nano-composite microcantilever can lead to the development of a rugged portable, handheld device for rapid and sensitive detection of explosive vapors.