Large-Scale Nonlinear Lumped and Integrated Field Simulations of Top-Orthogonal-to-Bottom-Electrode CMUT Architectures

Abstract

Capacitive micromachined ultrasonic transducers (CMUTs) promise many advantages over traditional piezoelectric transducers such as the potential to construct large, cost-effective 2-D arrays. To avoid wiring congestion issues associated with fully wired arrays, top-orthogonal-to-bottom electrode (TOBE) CMUT array architectures have proven to be a more practical alternative, using only 2N wires for an N ×N array. Optimally designing a TOBE CMUT array is a significant challenge due to the range of parameters from the device level up to the operating conditions of the entire array. Since testing many design variations can be prohibitively expensive, a simulation approach accounting for both the small and large-scale array characteristics of TOBE arrays is essential. In this paper, we demonstrate large-scale TOBE CMUT array simulations using a nonlinear CMUT lumped-circuit model. We investigate the performance of the array with different CMUT design parameters and array operating conditions. These simulated results are then compared with measurements of TOBE arrays fabricated using a sacrificial release process.

cMUT technology developments

“…A clear example of how cMUTs’ simplified routing and interconnection continues to be leveraged for 3D imaging applications in research is the several instances of “row-column addressed” (RCA) or “top-orthogonal-to-bottom electrode” (TOBE) arrays (see Fig. 8 ) [54] , [55] , [50] , [56] , [57] , [58] , [59] , [60] , [61] . The original underlying principle of these arrays is to use one set of electrodes to transmit a beam steered and focused in one lateral dimension (e.g., azimuth), while using the other set of electrodes on receive for steering and focusing in the other lateral dimension (e.g., elevation).…”

A Review on Analytical Modeling for Collapse Mode Capacitive Micromachined Ultrasonic Transducer of the Collapse Voltage and the Static Membrane Deflections

“…Modeling of CMUTs is challenging since it involves multidisciplinary domains including electronics, acoustics, mechanics and their interactions. Three main types of modeling/simulation methods including finite element method (FEM), analytical modeling, and equivalent circuit modeling (ECM) have been developed to facilitate the design of CMUT devices prior to fabrication [ 41 , 42 ] for the sake of reducing design iterations. Brenner et al presented a review on several aspects on CMUT including modeling, fabrication, and application, and both ECM and FEM modeling methods were discussed [ 26 ].…”