Metamaterial lens for real-time ultrasound beam steering using single-channel scalar control

Ultrasound sensors currently used by autonomous vehicles have short ranges and low resolutions, which limit their uses to proximity sensing. Metamaterial lenses promise to extend the range significantly due to the lenses' excellent beamforming ability, but designs reported so far either have fixed acoustic properties and thus are not able to easily ensonify in desired directions or employ arrays of transducers that are non-scalable and have high power consumption. In this presentation, we introduce a new type of ultrasound sensor composed of a single transducer and a reconfigurable metamaterial lens operating in air. The metamaterial lens requires less than 0.5 mm movements of a carefully designed surface to form and steer acoustic beams in real-time. The metamaterial tunes all the unit cells simultaneously with only one moving element. Remarkably, steering angles of ±20 deg are achieved despite the small actuation. The ability to control the ultrasound produced by a single transducer with small actuation is demonstrated experimentally.