Outperforming piezoelectric ultrasonics with highreliability single-membrane CMUT array elements  

作　　者：Eric B.Dew Afshin Kashani llkhechi Mohammad Maadi Nathaniel J.M.Haven Roger J.Zemp 

机构地区：[1]Department of Electrical and Computer Engineering,niversty of Alberta,Edmonton,Canada

出　　处：《Microsystems & Nanoengineering》2022年第3期61-75,共15页微系统与纳米工程（英文）

基　　金：funding from the Natural Sciences and Engineering Research Councilof Canada(RGPIN-201805788,STPGP 494293-16,RGPIN 355544);Canadian Institutes of Heath Research(PS 153007).

摘　　要：It has long been hypothesized that capacitive micromachined ultrasound transducers(CMUTs)could potentially outperform piezoelectric technologies.However,challenges with dielectric charging,operational hysteresis,and transmit sensitivity have stood as obstacles to these performance outcomes.In this paper,we introduce key architectural features to enable high-reliability CMUTs with enhanced performance.Typically,a CMUT element in an array is designed with an ensemble of smaller membranes oscillating together to transmit or detect ultrasound waves.However,this approach can lead to unreliable behavior and suboptimal transmit performance if these smaller membranes osilate out of phase or collapse at different voltages.In this work,we designed CMUT array elements composed of a single long rectangular membrane,with the aim of improving the output pressure and electromechanical efficiency.We compare the performance of three different modifications of this architecture:traditional contiguous dielectric,isolated isolation post(P),and insulated electrode-post(EP)CMUTs.EPs were designed to improve performance while also imparting robustness to charging and minimization of hysteresis.To fabricate these devices,a wafer-bonding process was developed with near-100%bonding yield.EP CMUT elements achieved electromechanical effciency values as high as 0.95,higher than values reported with either piezoelectric transducers or previous CMUT architectures.Moreover,all investigated CMUT architectures exhibited transmit effciency 2-3 times greater than published CMUT or piezoelectric transducer elements in the 1.5-2.0 MHz range.The EP and lip CMUTs demonstrated considerable charging robustness,demonstrating minimal charging over 500,000 collapse-snap-back actuation cycles while also mitigating hysteresis.Our proposed approach offers significant promise for future ultrasonic applications.

关 键 词：PIEZOELECTRIC ELEMENTS BONDING 

分 类 号：TB552[理学—物理]