MEMs sensors have the potential to serve as a low cost method for screening new drugs. To examine the feasibility of this technique, microbeams were designed such that an affinity between the beam surface (coated with a biomolecule) and a second biomolecule (simulating a potential drug) created a shift in the beam resonant frequency. PZT-actuated cantilever and bridge microbeams were fabricated and a baseline resonant frequency was established for each beam. Avidin and biotin were attached to the microbeams through a series of immersion and drying steps. Subsequent changes in the resonant frequency were recorded and compared for each beam. A drop in resonant frequency was consistently noted after the biotin molecule was introduced. To verify that the frequency shift could be attributed to the added mass of biotin, a biotin molecule with fluorescein dye was introduced. A direct correlation between fluorescent intensity and resonant frequency shift was observed.