Trimethylamine detection using microcantilever chemical sensors functionalized with a self-assembled monolayer

We report the detection of gas phase trimethylamine (TMA) using a microcantilever chemical sensor (MCS). The MCS is made from silicon-on-insulator (SOI) wafers and consists of two silicon dioxide layers and a single-crystalline-silicon piezoresistor sandwiched in-between. The MCS surface is chemically functionalized with a self-assembled monolayer (SAM) of 11-mercaptoundecanoic acid (11-MUA) via Au-SH covalent bonding on the microcantilever. The 11-MUA SAM adsorbs TMA through hydrogen bonding between the SAM and TMA molecules, resulting in the microcantilever deflection caused by the changes in the surface stress as a result of the hydrogen bonding based chemisorption. The limit of detection (LoD) 1.65 μg/L (0.6 ppm) is achieved.