Ultrasensitive detection of CrO42- using a microcantilever sensor

Microcantilevers modified with a self-assembled mono-layer respond sensitively to specific ion concentrations. Here, we report the detection of trace amounts of CrO42- using microcantilevers modified with a self-assembled monolayer of triethyl-12-mercaptododecylammonium bromide. The self-assembled monolayer was prepared on a silicon microcantilever coated with a thin layer of gold on one side. The microcantilever undergoes bending due to sorption of CrO42- ions on the monolayer-modified side. It was found that a concentration of 10(-9) M CrO42- can be detected using this technology in a now cell. Other anions, such as Cl-, Br-, CO32- (or HCO3-), and SO42-, have minimal effect on the deflection of this cantilever. The mechanics of the bending and the chemistry of cantilever modification are discussed.