A micro-electrical-mechanical system (MEMS) resonator device includes a top side electrode overlaid with a low water permeability hermeticity layer and an interface layer including a material (e.g., gold or a hydroxylated oxide surface) suitable for receiving a self-assembled monolayer (SAM) that may be functionalized with a functionalization (e.g., specific binding) material, with the foregoing layers being designed to have insubstantial impact on sensor performance. Atomic layer deposition may be used for deposition of the hermeticity and/or interface layers. The hermeticity layer protects the electrode material from attack in corrosive liquid environments, and the interface layer facilitates proper chemical binding of the SAM. Sensors and microfluidic devices incorporating MEMS resonator devices are also provided.