Abstract: An acoustic wave element includes: a substrate; a bonding structure on the substrate; a support layer on the bonding structure; a first electrode including a lower surface on the support layer; a cavity positioned between the support layer and the first electrode and exposing a lower surface of the first electrode; a piezoelectric layer on the first electrode; and a second electrode on the piezoelectric layer, wherein at least one of the first electrode and the second electrode includes a first layer and a second layer that the first layer has a first acoustic impedance and a first electrical impedance, the second layer has a second acoustic impedance and a second electrical impedance, wherein the first acoustic impedance is higher than the second acoustic impedance, and the second electrical impedance is lower than the first electrical impedance.

Abstract: A data transmission system includes a plurality of electronic devices, an verification server, and at least one access server. The electronic devices are verified by the verification server, and a data transmission group formed by the verified electronic devices. A receiving end in the data transmission group sends a command to the rest of the electronic devices in the data transmission group by the verification server. When the rest of the electronic devices receive the command, the rest of the electronic devices output metadata to the access server. The receiving end receives the metadata via the access server. The receiving end requests the transmitting end in the data transmission group for a physical file according to the metadata. The transmitting end transmits the physical file to the access server, and the access server transmits the physical file to the receiving end.