Table 1.

Description of several classic BAWs.

Type of Waves	Characteristics	Schematic of Wave Propagation
Longitudinal wave	Propagation through the medium in the same or opposite direction of particle vibration or oscillation. It is also called pressure waves.	Adapted with permission from Ref. [25].
Transverse wave	Propagation through the medium in the direction perpendicular to particle oscillation direction. It is also called shear-mode waves.	Adapted with permission from Ref. [4].
Lamb wave	It exists in thin plates, also called the plate wave, and the particle motion lies in the plane that is perpendicular to the plate and the propagation direction of the wave [25]. It is divided into symmetric waves and antisymmetric waves [24].	Adapted with permission from Ref. [24].