A MEMS device includes a substrate, at least one anchor on a surface of the substrate, and a vibrating body suspended over the substrate by the at least one anchor. The vibrating body includes a periodically poled piezoelectric thin-film layer, a first conductive layer, a second conductive layer, and a functional layer. The first conductive layer is on a first surface of the vibrating body opposite the surface of the substrate. The second conductive layer is on a second surface of the vibrating body opposite the first surface. The functional layer is over the first conductive layer. By including the functional layer over the first conductive layer, functionality may be added to the MEMS device, thereby increasing the utility thereof.