Design and fabrication of PMN-PT based high frequency ultrasound imaging devices integrated into medical interventional tools

This paper presents the rational for in vivo biopsy and the main technical challenges that must be overcome to realize this application. These include the need to achieve a small array package, the need for high frequency operation for high resolution, and the need for economical manufacturing. An array design is described, with 64 elements at 100 μm pitch, made with PMN-PT piezocrystal and operating at 15 MHz, to demonstrate resolution of 100 μm and the advantages of imaging close up. Techniques adopted to reduce the challenges are described, including, for example, spiral winding of a flexible circuit to achieve external connections. Results from prototypes to date include measurement of pulse-echo signals from a 20 MHz single element piezocrystal piezocomposite and first production of a 5 MHz demonstrator device. Further work will focus particularly on the method of interconnection of the flexible circuit to the array, and incorporation of the array within a biopsy needle.