Large-Scale Optical Ultrasound Transducer Arrays for High-Speed and High-Resolution 3D Acoustic Tomography

Texas A&M Engineering Experiment Station, College Station TX

Investigators

Abstract

Ultrasound imaging is essential in the clinic for early detection, diagnosis, and prognosis of many diseases. It provides real-time imaging speed, has no harmful ionizing radiation, and is low cost. However, current ultrasound imaging systems mainly produce two-dimensional planar images that may be inaccurate and/or difficult to interpret. Therefore, a three-dimensional (3D) imaging capability is essential for visualizing, navigating, and investigating patient anatomy and pathologies that are naturally 3D. To produce 3D images in a timely manner, an ultrasound imaging system must be able to capture the whole acoustic wave field emitted by the imaging target, such as a tumor. This requires a large array of ultrasound sensors or transducers, massive electrical cables, and sophisticated and expensive data acquisition electronics. Unfortunately, because of high system complexity and cost, 3D ultrasound imaging is still very limited in terms of performance and availability. In this project, a new optical technology will be developed to detect and convert the invisible acoustic wave field into a visible optical light field, which can be readily recorded by a camera. This “seeing the sound” approach is expected to address the performance and cost issues and open the door for many applications of 3D ultrasound imaging. This project will also provide unique multidisciplinary learning and training opportunities in microsystems, optics, acoustics and medical imaging for students and the general public. This project aims to achieve large-scale optical ultrasound transducer (OUT) arrays for enabling high-speed and high-resolution 3D acoustic tomography. Different from their electrical counterparts, OUTs convert ultrasound waves into optical signals through optomechanical modulation. This makes it possible to maintain high sensitivity even with a small element size. What’s more, ultrasound signals can be read out “wirelessly” via optical means without physical interconnects. However, one of the fundamental challenges in existing OUTs are their poor optical uniformity. Reading out ultrasound signals from multiple elements requires continual optical tuning, which is a tedious process and seriously limits the data acquisition speed. This project aims to address the fundamental bottleneck issues in current OUTs by exploring novel optical detector design, fabrication, and readout methods. Particularly, new mechanical/optical co-design and modeling will be combined with precision micromachining and tuning processes for achieving large-scale OUT arrays with controllable and uniform optical and acoustic properties. In addition, a new parallel approach based on pulsed illumination and camera capturing will be developed for fast ultrasound data acquisition. With wireless optical readout and natural immunity to electromagnetic interference, the OUT array could enable new acoustic imaging capabilities not possible before from tetherless, wearable, or remote imaging to seamless fusion with other mainstream imaging modalities. In addition, the high optical transparency of the OUT array can greatly facilitate the integration of hybrid optical and acoustic imaging. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.