Microcantilevers modified with a self-assembled mono-layer respond sensitiv
ely to specific ion concentrations. Here, we report the detection of trace
amounts of CrO42- using microcantilevers modified with a self-assembled mon
olayer of triethyl-12-mercaptododecylammonium bromide. The self-assembled m
onolayer 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 concent
ration of 10(-9) M CrO42- can be detected using this technology in a now ce
ll. Other anions, such as Cl-, Br-, CO32- (or HCO3-), and SO42-, have minim
al effect on the deflection of this cantilever. The mechanics of the bendin
g and the chemistry of cantilever modification are discussed.