MEMS and NEMS increasingly integrate multiple functions within compact platforms, enabled by piezoelectric and ferroelectric materials such as PZT, BaTiO3, AlN, ScAlN, PVDF, and Hf0.5Zr0.5O2. 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.
