Multielement Ring Array Based on Minute Size PMUTs for High Acoustic Pressure and Tunable Focus Depth Ledesma, Eyglis ; Zamora, Iván ; Uranga, Arantxa ; Barniol, Núria Abstract Publication: Sensors Pub Date: July 2021 DOI: 10.3390/s21144786 Bibcode: 2021Senso..21.4786L