Transmission and Reflective Ultrasound Images using PE-CMOS Sensor Array

The purpose of this study is to investigate the imaging capability of a CMOS (PE-CMOS) ultrasound sensing array coated with piezoelectric material. There are three main components in the laboratory setup: (1) a transducer operated at 3.5MHz-7MHz frequency generating unfocused ultrasound plane waves, (2) an acoustic compound lens that collects the energy and focuses ultrasound signals onto the detector array, and (3) a PE-CMOS ultrasound sensing array (Model I400, Imperium Inc. Silver Spring, MD) that receives the ultrasound and converts the energy to analog voltage followed by a digital conversion. The PE-CMOS array consists of 128×128 pixel elements with 85μm per pixel. The major improvement of the new ultrasound sensor array has been in its dynamic range. We found that the current PE-CMOS ultrasound sensor (Model I400) possesses a dynamic range up to 70dB. The system can generate ultrasound attenuation images of soft tissues which are similar to digital images obtained from an x-ray projection system. In the paper, we also show that the prototype system can image bone fractures using reflective geometry.