Abstract

A 40 MHz 128 channel linear phased array of capacitive micro machined ultrasonic transducers (CMUT) for ophthalmic anterior segment imaging application has been presented. The array has an aperture size of 2.41mm with an element pitch of 18.75mm. Each element is 10mm wide with an elevation depth of 5 mm. Each element of the array accommodates 264 small CMUT cells with a fill factor of 53.33%. Bisbenzocyclobutene (BCB), a low K polymer with excellent electrical, structural, and processing characteristics has been used to realize the CMUTs. The CMUTs were designed using a cross-verification platform comprised of Matlab™ based analytical and Intellisuite™ based 3-D electromechanical static and dynamic Finite Element Analysis (FEA). The analytical results for resonant frequency, diaphragm deflection profile and capacitance as a function of bias voltage were found to be in excellent agreement with a maximum deviation of 6.2% from the corresponding 3-D FEA results. Array analysis, focusing, and beamsteering in the pulse echo mode were performed using the Vantage128™ ultrasonic research platform from Verasonics™ to determine the imaging performance at a depth of 3mm and higher from the array surface. The Vantage128™ simulation results are in excellent agreement with published ophthalmic anterior segment imaging results that validates the design methodology.

Keywords: Phase array; Ophthalmic diagnostic imaging; Beam steering; Verasonics; Bisbenzocyclobutene; IntelliSuite; Sonometrics; Cmut; Polyvinylidene; Difluoride Transducer; Corneal Stroma; Specular Cornea; Piezoceramic; Glaucoma; penetration; polyvinylidene; emphasizing; corneal epithelium; ophthalmic; Matlab