Development of a 50 MHz Linear Array for Endoscopic Imaging

Endoscopic micro-ultrasound can potentially im-prove imaging of diseased tissue structure and function if the probe can be positioned near the tissue of interest. We previously reported the fabrication of miniaturized linear arrays using thin, high-density flexible printed circuit boards (FPCBs) connected to array elements with laser patterned deposited metals. Here we extend previous work to limit the area used for electrical connection to array elements and place element signal electrodes on the back surface of the array so the ground electrode can be at the front face and we use extended electroplated signal electrodes to create bond-pads at the edges to achieve an endoscopic form factor. We demonstrate fabrication with a forward-viewing, 50 MHz, 64-element linear array that fits within a 3-mm-diameter lumen. The array was 2.5 mm (azimuth) by 1.6 mm (elevation), had a mean resonant frequency of 48.2 MHz and a mean kt of 0.41. Laser Doppler vibrometry measurements allow further investigation of the device performance. Phantom images are shown to demonstrate array capability.