A vibration device includes a tubular body with a cavity, a first opening end surface, and a second opening end surface, a piezoelectric device joined to the first opening end surface, and a translucent cover joined to the second opening end surface. The tubular body and the piezoelectric device are joined to each other with a first adhesive layer, and the tubular body and the translucent cover are joined to each other with a second adhesive layer.

A piezoelectric device that includes a film that has a first main surface and a second main surface, and has piezoelectricity; a first substrate; and a first connection member that connects the film to the first substrate. The first connection member is a thermosetting resin, and a curing temperature of the first connection member is lower than a temperature at which the film thermally contracts.

A piezoelectric device that includes a film that has a first main surface and a second main surface, and has piezoelectricity; a first substrate; and a first connection member that connects the film to the first substrate. The first connection member is a thermosetting resin, and a curing temperature of the first connection member is lower than a temperature at which the film thermally contracts.

A piezoelectric device has a good piezoelectric characteristic, while suppressing a leakage current between electrodes. The piezoelectric device has a first substrate, a first conductive film provided on the first substrate, a piezoelectric layer formed of an inorganic material and provided on the first conductive film, an adhesive layer provided on the piezoelectric layer, and a second conductive film provided on the adhesive layer.

A method of forming a microphone device includes: forming a through-hole in a substrate wafer; providing a second wafer; bonding the second wafer to the substrate wafer; and forming a top electrode over a first surface of a single-crystal piezoelectric film of the second wafer. The second wafer may include the single-crystal piezoelectric film. The single-crystal piezoelectric film may have a first surface and an opposing second surface. The second wafer may further include a bottom electrode arranged adjacent to the second surface, and a support member over the single-crystal piezoelectric film. The through-hole in substrate wafer may be at least substantially aligned with at least one of the top electrode and the bottom electrode.

A method of forming a microphone device includes: forming a through-hole in a substrate wafer; providing a second wafer; bonding the second wafer to the substrate wafer; and forming a top electrode over a first surface of a single-crystal piezoelectric film of the second wafer. The second wafer may include the single-crystal piezoelectric film. The single-crystal piezoelectric film may have a first surface and an opposing second surface. The second wafer may further include a bottom electrode arranged adjacent to the second surface, and a support member over the single-crystal piezoelectric film. The through-hole in substrate wafer may be at least substantially aligned with at least one of the top electrode and the bottom electrode.

A method of manufacturing a substrate for an acoustic wave device includes: a substrate joining step of joining a piezoelectric material layer to a surface on one side of a support substrate; a grinding step of grinding the piezoelectric material layer; a removal amount map forming step of measuring in-plane thickness of the piezoelectric material layer by an optical thickness meter, and calculating a removal amount for the piezoelectric material layer for adjusting thickness variability of the piezoelectric material layer to or below a threshold on the basis of each coordinate in the plane, to form a removal amount map; a laser processing step of applying a pulsed laser beam of such a wavelength as to be absorbed in the piezoelectric material layer, to selectively remove the piezoelectric material layer, based on the removal amount map; and a polishing step of polishing the surface of the piezoelectric material layer.

A piezoelectric-body film joint substrate includes a substrate, a substrate electrode provided on the substrate, a first piezoelectric-body film stuck on the substrate electrode and including a first piezoelectric film and a first upper electrode film formed on the first piezoelectric film, and a second piezoelectric-body film stuck on the first upper electrode film and including a second piezoelectric film different from the first piezoelectric film and a second upper electrode film formed on the second piezoelectric film.

A piezoelectric-body film joint substrate includes a substrate, a substrate electrode provided on the substrate, a first piezoelectric-body film stuck on the substrate electrode and including a first piezoelectric film and a first upper electrode film formed on the first piezoelectric film, and a second piezoelectric-body film stuck on the first upper electrode film and including a second piezoelectric film different from the first piezoelectric film and a second upper electrode film formed on the second piezoelectric film.

A method of making an actuator for a resonant acoustic pump comprises: forming a through-hole in a ceramic material of a piezoelectric layer of the actuator, prior to assembly of the piezoelectric layer with other layers of the actuator; forming a through-hole in a flexible circuit layer of the actuator; forming a through-hole in an end plate layer of the actuator; and disposing each of the piezoelectric layer and the end plate layer on a respective one of opposite sides of the flexible circuit layer, so that the through-holes align to provide a passageway for a fluid to pass through the actuator.