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There is a high demand for novel flexible micro-devices for energy harvesting from low-frequency and random mechanical sources. The research of new functional designs is required to strategically enhance the performances and to increase the control on mechanical flexibility. In this work we report the fabrication and characterization of bi-stable and statically balanced thin-film piezoelectric transducers based on Aluminum Nitride (AlN). The device consists of a piezoelectric layer sandwiched between two thin Molybdenum electrodes that were deposited on a Kapton substrate by reactive sputtering and patterned by UV lithography. In order to improve the out-of-plane flexibility, the mechanical design is distinguished by a post-buckled flexure that introduces a negative stiffness to compensate the otherwise positive stiffness of the system. The buckling was introduced by a new method, called Package-Induced Preloading (PIP) where the mechanisms are laminated over a package with a geometry extending out-of-plane. The induced buckling resulted in bi-stable and statically balanced mechanisms which demonstrated an enhanced voltage output during a triggered snapping step. A preliminary study shows potential for the statically balanced designs and the PIP method for wind energy harvesting, revealing prospective applications and future improvements for the development of energy harvesters. [Display omitted] • Low-frequency/random mechanical energy sources (fluid flows) can be addressed efficiently through piezoelectric transducers. • Static balancing and bi-stability to produce new designs with controlled movements and enhanced performances. • Bi-stable and statically balanced thin-film AlN piezoelectric transducers for mechanical energy harvesting are developed. • The mechanisms are preloaded through a new method (Package-Induced Preloading, PIP) using an out-of-plane 3D printed package. • The induced buckling resulted in 8-fold enhanced voltage output during a triggered snapping step. [ABSTRACT FROM AUTHOR]