Piezoelectric self-sensing of adsorption-induced microcantilever bending

A self-sensing, self-actuating, piezoelectric microcantilever is used to detect adsorption-induced bending. Bending is measured by bringing the resonating cantilever into intermittent contact with a surface, the elevation of which is maintained by a piezotube in feedback. When the cantilever bends, its oscillatory amplitude changes and the piezotube is adjusted to compensate. Cantilever amplitude is detected using the voltage output of the piezoelectric film. Bending in this test was caused by mercury adsorption onto gold. A 50 ppb mercury concentration in nitrogen gas was detected.