Design, modeling and characterization of a 35MHz 1-D CMUT phased array

Abstract

High frequency ultrasound arrays have applications ranging from imaging of small animals, skin and eye to intravascular ultrasound (IVUS). We describe an application where a guidewire IVUS system uses high frequency phased arrays with integrated electronics placed directly on the guidewire rather than a catheter for imaging. Multiple arrays provide the full transverse cross section of the artery during percutaneous interventions. We focus on a 1-D CMUT phased array to be used in the guidewire IVUS. CMUTs are particularly suitable for this application with their ease of fabrication and single chip electronics integration. The array frequency is chosen to be around 35-40MHz with 10MHz bandwidth so that the 1-D CMUT phased array with a 300um wide aperture can closely match the lateral resolution of a current 20MHz, 3.5F solid state IVUS array. Here we discuss the initial design, large signal modeling, fabrication and experimental characterization of a 12 element, 300x1000um CMUT array with 25um pitch. The electrical and acoustic characterization results for a CMUT array with 20um square membranes are presented. Modeling results for different size membranes indicating adequate performance for higher bandwidth applications are also discussed.

Recent Advances in Transducers for Intravascular Ultrasound (IVUS) Imaging

“…Furthermore, CMUTs are also CMOS-compatible and have small form factor [64]. Currently, three types of CMUTs have been reported for IVUS imaging applications: cylindrical CMUT array [65], phased CMUT array [66][67][68] Compared with conventional piezoelectric ultrasound transducers, PMUT demonstrates its uniqueness for IVUS imaging. Contrary to conventional piezoelectric ultrasound transducer, PMUT is compatible with complementary metal oxide semiconductor (CMOS), which means that the fabrication process of PMUT can be easily integrated with supporting electronic circuits.…”

“…Furthermore, CMUTs are also CMOS-compatible and have small form factor [64]. Currently, three types of CMUTs have been reported for IVUS imaging applications: cylindrical CMUT array [65], phased CMUT array [66][67][68] Due to the flexibility of the CMUT array, it could be wrapped around a 3 Fr catheter tip for side looking IVUS imaging. Xu et al [66] designed and fabricated four 12-element 1D CMUT phased arrays for cross-sectional imaging of artery.…”

Capacitive micromachined ultrasound transducers for intravascular ultrasound imaging

“…Therefore, some research groups focus on IVUS catheter design with CMUTphased arrays. For example, Xu et al 66 designed and fabricated a 12-element 1-D CMUT-phased array (Fig. 4a).…”

Optical data link assembly for 360 µm diameter IVUS on guidewire imaging devices

“…The next logical step is to implement IVUS on a guidewire, the instrument that is inserted prior to the catheter during PCI. A recent proposal introduces a phased CMUT array inside a Ø 360 thick guidewire [7].…”