Development of a 35-MHz piezo-composite ultrasound array for medical imaging

TLDR

The study presents the design and fabrication of a 64‑element, 35‑MHz composite ultrasonic array for ocular imaging. The array consists of 2‑2 composite elements diced from high‑density Navy Type VI ceramic, spaced 50 µm apart, connected via a custom flexible circuit and 75‑ohm coaxial cable, with elevation focusing achieved by a cylindrically shaped epoxy lens, and was fabricated and tested using a synthetic‑aperture reconstruction algorithm on a tungsten‑wire phantom. Measured performance shows an average bandwidth of 55 %, 23‑dB insertion loss, crosstalk below –24 dB, and imaging resolution better than 50 µm axially and 100 µm laterally.

Abstract

This paper discusses the development of a 64-element 35-MHz composite ultrasonic array. This array was designed primarily for ocular imaging applications, and features 2-2 composite elements mechanically diced out of a fine-grain high-density Navy Type VI ceramic. Array elements were spaced at a 50-micron pitch, interconnected via a custom flexible circuit and matched to the 50-ohm system electronics via a 75-ohm transmission line coaxial cable. Elevation focusing was achieved using a cylindrically shaped epoxy lens. One functional 64-element array was fabricated and tested. Bandwidths averaging 55%, 23-dB insertion loss, and crosstalk less than -24 dB were measured. An image of a tungsten wire target phantom was acquired using a synthetic aperture reconstruction algorithm. The results from this imaging test demonstrate resolution exceeding 50 microm axially and 100 microm laterally.