Enhanced mass sensitivity of stress-free, silicon nanowire-grown microcantilever sensors

A thin catalytic layer of nickel was evaporated onto one side of silicon microcantilevers and amorphous silicon nanowires were synthesized on the nickel surface. When nanowire-grown cantilevers were exposed to mercaptohexanol vapor, their mass sensitivity was almost two orders of magnitude greater than that of the corresponding plain cantilever due to the increase in surface area afforded by the nanowires, whereas adsorption of mercaptohexanol induced negligible deflection of the nanowire-grown cantilevers. This indicates that the gold-coated nanowire-grown cantilever can be used as a sensitive, stress-free sensor whose spring constant is not affected by the adsorption of alkanethiols.