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 20s with response and recovery time of similar to 3s and 4s, 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. (C) 2013 Elsevier B.V. All rights reserved.