An ultrasonic sensor includes a two-dimensional array of ultrasonic transducers, a contact layer, a matching layer between the two-dimensional array and the contact layer, where the matching layer has a non-uniform thickness, and an array controller configured to control activation of ultrasonic transducers during an imaging operation for imaging a plurality of pixels within the two-dimensional array of ultrasonic transducers. During the imaging operation, the array controller is configured to activate different subsets of ultrasonic transducers associated with different regions of the two-dimensional array of ultrasonic transducers at different transmission frequencies, where the different frequencies are determined such that a thickness of the matching layer at a region is substantially equal to a quarter wavelength of the first transmission frequency for the region. The array controller is also configured to combine the plurality of pixels into a compound fingerprint image that compensates for the non-uniform thickness of the matching layer.

An imaging device includes a transducer that includes an array of piezoelectric elements formed on a substrate. Each piezoelectric element includes at least one membrane suspended from the substrate, at least one bottom electrode disposed on the membrane, at least one piezoelectric layer disposed on the bottom electrode, and at least one top electrode disposed on the at least one piezoelectric layer. Adjacent piezoelectric elements are configured to be isolated acoustically from each other. The device is utilized to measure flow or flow along with imaging anatomy.

A backing panel for a transducer of an ultrasound scanner probe, comprising a core layer sandwiched by a first skin layer and a second skin layer. The transducer may comprise a front portion and a rear portion, where the front portion points to a direction of a target for the ultrasound scanner probe, and the first skin layer is adjacent to the rear portion of the transducer.

A piezoelectric element has a first electrode layer, a piezoelectric layer on the first electrode layer, a second electrode layer on the piezoelectric layer, a third electrode layer on part of the second electrode layer and including third metal, and an insulating layer covering at least a part of the piezoelectric layer not provided with the second electrode layer and having an aperture exposing a part of the second electrode layer. The second electrode layer has a first layer including first metal and a second layer including second metal on the first layer. The second layer is exposed in the aperture. A difference in standard redox potential between the second metal and the third metal is smaller than a difference in standard redox potential between the first metal and the third metal.

Described are transducer assemblies and imaging devices comprising: a microelectromechanical systems (MEMS) die including a plurality of piezoelectric elements; a complementary metal-oxide-semiconductor (CMOS) die electrically coupled to the MEMS die by a first plurality of bumps and including at least one circuit for controlling the plurality of piezoelectric elements; and a package secured to the CMOS die by an adhesive layer and electrically connected to the CMOS die.

Microelectromechanical (MEMS) devices and associated methods are disclosed. Piezoelectric MEMS transducers (PMUTs) suitable for integration with complementary metal oxide semiconductor (CMOS) integrated circuit (IC), as well as PMUT arrays having high fill factor for fingerprint sensing, are described.

A transducer assembly includes: a microelectromechanical systems (MEMS) die including a plurality of piezoelectric elements; a complementary metal-oxide-semiconductor (CMOS) die electrically coupled to the MEMS die by a first plurality of bumps and including at least one circuit for controlling the plurality of piezoelectric elements; and a package secured to the CMOS die by an adhesive layer and electrically connected to the CMOS die.

An ultrasonic probe includes: a piezoelectric element; and a backing material including a matrix resin and thermally conductive particles, arranged on one direction side with respect to the piezoelectric element, wherein a ratio of thermal conductivity of the backing material in a thickness direction to the thermal conductivity of the backing material in a horizontal direction is 3 or more.

Disclosed herein are acoustic transmission systems comprising an acoustic wave generator configured to generate an acoustic wave and propagate the acoustic wave through a tissue of a specimen, and a non-Hermitian complementary metamaterial (NHCMM) configured to add a first amount of energy amplification coherently to the acoustic wave to account for energy loss in the acoustic wave as a result of the wave propagating through the tissue of the specimen. The acoustic wave generator can be an ultrasound generator, and the tissue can be a cranium.

Ultrasonic devices include a transducer having a piezoelectric element therein that may operate as an acoustic signal receiving surface and/or an acoustic signal generating surface. At least one acoustic matching layer is provided on the piezoelectric element. This at least one acoustic matching layer may be configured as a composite of N acoustic matching layers, with a first of the N acoustic matching layers contacting the primary surface of the piezoelectric element. This first acoustic matching layer may have an acoustic impedance equivalent to Z.sub.L1, where N is a positive integer greater than zero. In some embodiments of the invention, the magnitude of Z.sub.L1 may be defined as: 0.75 ((Z.sub.p).sup.N+1(Z.sub.g)).sup.1/(N+2)Z.sub.L11.25 ((Z.sub.p).sup.N+1(Z.sub.g)).sup.1/(N+2), where Z.sub.p is the acoustic impedance of the piezoelectric element (e.g., lead zirconate titanate (PZT)) and Z.sub.g is the acoustic impedance of a compatible gas.