Detection of formaldehyde vapor using mercaptophenol-coated piezoresistive cantilevers

Piezoresistive cantilevers coated with mercaptophenol self-assembled monolayers were used to detect formaldehyde vapor at room temperature. The three isomers of mercaptophenol, namely 2-, 3-, and 4-mercaptophenol, were tested as probe molecules. The 3-mercaptophenol-coated cantilever showed the largest deflection due to high reactivity between formaldehyde and 3-mercaptophenol. When the 3-mercaptophenol-coated cantilever was exposed to interferents such as benzene, toluene, p-xylene, water, or ethanol, the deflection direction of the cantilever was the opposite of that induced by the chemical reaction with formaldehyde, indicating that 3-mercaptophenol is very specific to formaldehyde. The detection limit of the 3-mercaptophenol-coated cantilever was determined to be better than 0.01 ppm.