Fabrication and Performance of a Miniaturized and Integrated Endoscope Ultrasound Convex Array for Digestive Tract Imaging

Objective: this work presents the design, fabrication, and testing of a miniaturized and integrated ultrasound endoscope for use as an in situ digestive diagnostic device to facilitate real-time ultrasound guidance of intervention treatments. Methods: we designed an optimal structure to integrate an auto-focus 5-megapixel camera module with an 8-MHz, 64-element curvilinear ultrasonic array in one miniaturized package. A novel three-axis auto-focusing voice coil motor (VCM) was designed and manufactured for the camera module to move the lens position for auto-focusing and to adjust the lens tilt. Results: the results showed that the array had a center frequency of 8.09 MHz and a –6-dB fractional bandwidth of 83%. At the center frequency, the two-way insertion loss was 40.6 dB. Endoscopic ultrasound imaging demonstrated satisfactory performance for imaging an anthropomorphic phantom of the esophagus. By slightly adjusting the tilt angle of the optical axis of the lens, the optical image captured by the auto-focusing lens obtained improved definition regardless of changes in the view angle of the camera with respect to the objects being captured. Conclusion: the integrated convex ultrasound endoscope, possessing minimal size, improved optical imaging definition, and good ultrasound imaging performance, can become a useful tool in digestive tract imaging. Significance: the miniaturized and integrated convex ultrasound endoscope can facilitate real-time ultrasound intervention guidance, reducing risks associated with the operation.