Abstract: An acoustic lens to steer an acoustic beam includes a first structure, a second structure spaced from the first structure, an array of projections disposed between the first and second structures, each projection of the array of projections extending from the first structure toward the second structure to define a respective gap between the projection and the second structure, and an actuator configured to move the first structure, the second structure, or the array of projections for collective adjustment of the respective gaps of the array of projections. Each projection is configured to define one or more respective unit cells, each unit cell having a sub-wavelength size relative to the acoustic beam to establish an effective refractive index profile for the acoustic beam between the first and second structures.

Abstract: A battery cell in which a liquid electrolyte is disposed and an acoustic transducer in mechanical communication with the battery cell. The acoustic transducer is configured to generate acoustic waves. The acoustic waves have a wavelength larger than a dimension of the battery cell such that the acoustic waves generate cavitation bubbles in the electrolyte.

Abstract: Metamaterial particles having active electronic components are disclosed. According to one aspect, a metamaterial particle in accordance with the subject matter disclosed herein can include a field sensing element adapted to sense a first field and adapted to produce a sensed field signal representative of the first field in response to sensing the first field. Further, the metamaterial particle can include an active electronic component adapted to receive the sensed field signal and adapted to produce a drive signal based on the sensed field signal. A field generating element can be adapted to receive the drive signal and adapted to produce a second field based on the drive signal.