Abstract: Piston mode Lamb wave resonators are disclosed. A piston mode Lamb wave resonator can include a piezoelectric layer, such as an aluminum nitride layer, and an interdigital transducer on the piezoelectric layer. The piston mode Lamb wave resonator has an active region and a border region, in which the border region has a velocity with a lower magnitude than a velocity of the active region. The border region can suppress a transverse mode.

Abstract: Embodiments of this application provide a composite structure including a substrate layer and a functional layer disposed on a surface of at least one side of the substrate layer. The substrate layer includes a first support member and a second support member that are disposed side by side and a bendable connecting member connected to and disposed between the first support member and the second support member. A material of the first support member and the second support member includes a hard rubber fiber composite material, and the functional layer includes one or more of an electrically conductive layer, a thermally conductive layer, or an impact-resistant layer.