Multifunctional MEMS, NEMS, micro/nano-structures enabled by piezoelectric and ferroelectric effects

MEMS and NEMS increasingly integrate multiple functions within compact platforms, enabled by piezoelectric and ferroelectric materials such as PZT, BaTiO₃, AlN, ScAlN, PVDF, and Hf_0.5Zr_0.5O₂. These materials support devices including mechanical sensors, RF resonators for gas detection, energy harvesters, non-volatile memories such as FeRAM and FeFETs, and neuromorphic computing arrays, as well as microspeakers and microphones for compact audio interfaces. They also play a key role in reconfigurable photonic components through acousto-optic and electro-optic modulation. This review examines materials, device designs, and integration strategies shaping next-generation intelligent microsystems across domains such as Artificial Intelligence of Things (AIoT), wearables, and robotics.