This study proposes a fabrication-aware topology optimization framework that simultaneously determines substrate carving and electrode patterning for unimorph-type piezoelectric energy harvesters. The method employs a level-set representation with anisotropic regularization to satisfy Si deep reactive ion etching (DRIE) constraints, and it deliberately leaves the piezoelectric film on the entire substrate so that the balance of residual stresses among the multilayer films is maintained. The optimization minimizes the inverse electromechanical coupling coefficient under target resonant frequency and minimum output voltage requirements. Sensitivities obtained from the adjoint method guide a simultaneous update of the two level-set functions that represent the substrate and the electrode pattern; the iteration proceeds until convergence. A partial short-circuit boundary condition is also introduced: the electric field is constrained to vanish only inside the electrode-sandwiched region of the piezoelectric film, whereas a non-zero electric field persists in regions not covered by the electrodes. Eigenvalue analyses under both open- and short-circuit conditions are solved in a consistent finite-element framework to quantify the resulting frequency shifts. Numerical simulations predict that the proposed design improves the electromechanical coupling coefficient and meets the specified resonance targets without violating fabrication rules; they also suggest a tendency toward cantilever flatness. This point will be verified through prototype fabrication and experimental evaluation in future work. Preliminary numerical findings will be reported in the presentation, and full experimental validation is planned as a subsequent study.
MIYAJIMA et al. (Wed,) studied this question.