An object is to provide a piezoelectric film that has excellent flexibility in a high temperature environment at higher than 50° C. and exhibits good flexibility even at room temperature, a laminated piezoelectric element in which the piezoelectric films are laminated, and an electroacoustic transducer using the piezoelectric film or the laminated piezoelectric element. The object is solved by the piezoelectric film including: a polymer-based piezoelectric composite material in which piezoelectric particles are dispersed in a matrix including a polymer material; and electrode layers provided on both surfaces of the polymer-based piezoelectric composite material, in which a loss tangent at a frequency of 1 Hz according to dynamic viscoelasticity measurement has a maximal value of greater than or equal to 0.1 existing in a temperature range of higher than 50° C. and lower than or equal to 150° C., and has a value of greater than or equal to 0.08 at 50° C.

A piezoelectric-body film joint substrate includes a substrate, a first electrode provided on the substrate, a first piezoelectric-body film stuck on the first electrode and including a first piezoelectric film and a first upper electrode film formed on the first piezoelectric film, a second electrode provided on the substrate, and a second piezoelectric-body film stuck on the second electrode and including a second piezoelectric film different from the first piezoelectric film and a second upper electrode film formed on the second piezoelectric film, wherein a height from an upper surface of the substrate, on which the first electrode and the second electrode are formed, to a top of the first upper electrode film and a height from the upper surface of the substrate to a top of the second upper electrode film differ from each other.

A piezoelectric-body film joint substrate includes a substrate, a first electrode provided on the substrate, a first piezoelectric-body film stuck on the first electrode and including a first piezoelectric film and a first upper electrode film formed on the first piezoelectric film, a second electrode provided on the substrate, and a second piezoelectric-body film stuck on the second electrode and including a second piezoelectric film different from the first piezoelectric film and a second upper electrode film formed on the second piezoelectric film, wherein a height from an upper surface of the substrate, on which the first electrode and the second electrode are formed, to a top of the first upper electrode film and a height from the upper surface of the substrate to a top of the second upper electrode film differ from each other.

A piezoelectric film integrated device includes a substrate; an electrode provided on the substrate; a first piezoelectric element that is provided on the electrode and includes a first monocrystalline piezoelectric film and a first electrode film superimposed on the first monocrystalline piezoelectric film; and a second piezoelectric element that is provided on the first piezoelectric element and includes a second monocrystalline piezoelectric film and a second electrode film superimposed on the second monocrystalline piezoelectric film.

A piezoelectric film integrated device includes a substrate; an electrode provided on the substrate; a first piezoelectric element that is provided on the electrode and includes a first monocrystalline piezoelectric film and a first electrode film superimposed on the first monocrystalline piezoelectric film; and a second piezoelectric element that is provided on the first piezoelectric element and includes a second monocrystalline piezoelectric film and a second electrode film superimposed on the second monocrystalline piezoelectric film.

A wafer scale ultrasonic sensor assembly includes a wafer substrate, an ultrasonic element, first and second protective layers, conductive wires, a transmitting material, an ASIC, a conductive bump, and a soldering portion. The wafer substrate includes a via. The ultrasonic element is exposed to the via. The conductive wires are on the first protective layer and connected to the ultrasonic element. The second protective layer covers the conductive wires, and the second protective layer has an opening corresponding to the ultrasonic element. The transmitting material contacts the ultrasonic element. The ASIC is connected to the wafer substrate, so that the via forms a space between the ASIC and the ultrasonic element. The conductive pillar is in a via defined through the ASIC, the wafer substrate, and the first protective layer, and the conducive pillar is respectively connected to the conductive wires and the soldering portion.

An ultrasound transducer and a method of making this transducer, where the transducer includes at least two piezoelectric elements, oriented adjacent to each other in a stack. Each piezoelectric element includes a first surface which includes an electrode of a first polarity, a second surface which includes an electrode of a second polarity, a thickness between the first surface and the second surface, and an ultrasound transmitting surface. This surface does not include an electrode. The transducer also includes a first electrical connection between a surface of a first of the at least two piezoelectric elements of the first polarity and a surface of a second of the at least two piezoelectric elements of the first polarity and a second electrical connection between a surface of a first of the at least two piezoelectric elements of the second polarity and a surface of a second of the at least two piezoelectric elements of the second polarity.

A hybrid ferroelectric/non-ferroelectric piezoelectric microresonator is disclosed. The hybrid microresonator uses a ferroelectric layer as the actuator as ferroelectric materials typically have higher actuation coefficients than non-ferroelectric piezoelectric materials. The hybrid microresonator uses a non-ferroelectric piezoelectric layer as the sensor layer as non-ferroelectric piezoelectric materials typically have higher sensing coefficients than ferroelectric materials. This hybrid microresonator design allows the independent optimization of actuator and sensor materials. This hybrid microresonator design may be used for bulk acoustic wave contour mode resonators, bulk acoustic wave solidly mounted resonators, free-standing bulk acoustic resonators, and piezoelectric transformers.

An in-situ poled ferroelectric prints with true 3D geometry is provided with an intercalated electrode design where soft polymer matrixes are selected for the ferroelectric layers, and rigid polymer matrixes are selected for the electrode layers, thus mimicking nacre architecture with a ceramic-like piezoelectric property and bone-like fracture toughness. Lithium-doped potassium sodium niobite (Li-KNN) microparticles may be used to produce ferroelectric properties and to create strong interfacial bonding with the interfacing electrode layers. Polylactic acid (PLA) in the electrode layers may be used to facilitate strong interfacial bonding with the Li-KNN microparticles.

A piezoelectric microelectromechanical structure is provided with a piezoelectric stack having a main extension in a horizontal plane and a variable section in a plane transverse to the horizontal plane. The stack is formed by a bottom-electrode region, a piezoelectric material region arranged on the bottom-electrode region, and a top-electrode region arranged on the piezoelectric material region. The piezoelectric material region has, as a result of the variable section, a first thickness along a vertical axis transverse to the horizontal plane at a first area, and a second thickness along the same vertical axis at a second area. The second thickness is smaller than the first thickness. The structure at the first and second areas can form piezoelectric detector and a piezoelectric actuator, respectively.