An ultrasonic imaging system has a bias-switchable, ultrasonic transducer array and a bipolar voltage source. The array has a dielectric layer having a top surface and a bottom surface; top and bottom electrode strips in electrical contact with the top and bottom surface of the dielectric layer, the bottom electrode strips being oriented at a non-zero angle relative to the top electrode strips. There is an acoustic matching layer or multiplicity of matching layers on the front-side of the array and a leakage-current mitigation layer. The bipolar voltage source is connected to each of the top and bottom electrode strips to induce a polarization in the dielectric layer, the bipolar voltage source being capable of switching between a high voltage state and a low voltage state. A controller controls the bipolar voltage source, and pulsing to and receiving signals from the top and bottom electrode strips.

A nebuliser for nebulising liquid droplets includes a housing; at least one piezoelectric substrate accommodated within the housing and having a transducer surface upon which is located at least one electroacoustic transducer for generating acoustic wave energy within the substrate, and an opposing non-transducer surface; and a liquid supply system for supplying a liquid to at least one of the transducer and non-transducer surfaces. The liquid supply system includes a reservoir for accommodating the liquid, and at least one relatively rigid supply conduit in contact with the substrate for supplying the liquid from the reservoir to the substrate.

Disclosed are systems and devices for absorbing flexural waves. In one example, a pair of scatterers for absorbing a flexural wave acting on a structure includes a monopole scatterer and a dipole scatterer configured to be mounted to the structure at the same location.