Electromechanical identification of molecules adsorbed on microcantilevers

An alternating current was applied to a gold-coated silicon microcantilever in a sodium chloride solution. The electric field applied through the gold layer attracts oppositely charged ions onto the cantilever, and the resulting variation of surface charges induces changes in the surface stress that result in oscillation of the cantilever. The bending profiles of cantilevers coated with 1-mercaptoethanol, 1-mercaptopropanol, and 1-mercaptohexanol excited by a square-wave electric field depended on the chain lengths of the layers: a layer comprising longer hydrocarbon chains more strongly hinders ions from being adsorbed on the gold layer, resulting in the cantilever bending more slowly.