Tiltable Ultrasonic Transducers: Concept, Beamforming Methods and Simulation

This paper investigates the concept of tiltable ultrasonic transducers, and their application in focusing and steering in a transducer array. Results of simulated imaging processes suggest that physical focusing and steering with tiltable transducers is promising in reducing grating lobe and side lobe artifacts, and preserving the beam power, especially when steering to large angles. We propose that one embodiment of the tiltable transducers can be adaptive capacitive micromachined ultrasonic transducers (CMUTs) modeled as clamped plate radiators. By applying different levels of electrical field on their split electrodes, one can adjust the shape and orientation of the adaptive CMUTs adaptively and dynamically, creating a tilted effect in the beam direction. The feasibility of using adaptive CMUTs to implement tiltable transducers is studied using finite element modeling (FEM) and analytical modeling. Experimental measurements of the tilted behavior of fabricated adaptive CMUTs are also provided. Possible applications of the tiltable transducers, including spatial compounding, high intensity focused ultrasound (HIFU), adaptive imaging, and harmonic imaging, are discussed.