"Microscale Ultrasound Systems for Minimally Invasive Imaging in the Heart"
F. Levent Degertekin, PhD
George W. Woodruff School of Mechanical Engineering
Catheter-based treatments are used in a broad range of heart diseases including cardiac dysrhythmias, congenital heart defects as well as coronary heart disease, which is the leading cause of death in the US. Although fluoroscopy and coronary angiography are still the gold standard imaging tools, with longer and more challenging procedures such as trans-catheter valve replacements, new and more effective nonionizing real time imaging tools are needed. Miniature phased array ultrasound imaging probes with central cavities are particularly suitable for these interventions since they enable direct imaging in front of catheters and provide delivery channels for therapeutic devices. Volumetric ultrasound imaging catheters with extremely flexible and deflectable distal tips would provide the clinicians exceptional capability for spatial mapping during these procedures. We have been developing technologies for ultimately miniaturized 3D ultrasound imaging arrays where the front-end electronics as well as over 100 ultrasound transducers are integrated on a 300um thick, 1.2mm diameter silicon donut to be placed at the tip of the imaging catheters. This is achieved by monolithic integration of capacitive micromachined ultrasonic transducers and CMOS electronics, namely the CMUT-on-CMOS technology. In this talk, we will describe the design, fabrication and testing of these microsystems and present imaging results on relevant biological samples and phantoms. We will also discuss possible future applications of these systems.