This proposed program uses advanced patterning and alignment technology from the multiplayer ceramic packaging industry to construct 2-D ultrasound arrays with multiplayer PZT posts to increase capacitance and, therefore, transducer signal to noise ratio (SNR). Conventional 2-D transducer arrays provide many advantages for medical ultrasound imaging, but the performance often suffers from the low capacitance elements and poor impedance matching. Use of cofired multiplayer technology to produce individual array elements is a good solution to the impedance mismatch problem because capacitance increases with the square of the number of layers in an element. It was estimated that a 3-layer 2-D array will increase SNR by 9 dB and a 5 layer array will achieve close to 14 dB improvements. Making electrical connections to fine scale, three dimensional ceramic structures was not possible until recently. The progress made in the electronic ceramic packaging industry in the past 5 years, with 75 and 25 1lm resolution for via punching and precision alignment, respectively, has made this concept feasible. For the Phase I effort, we will demonstrate the feasibility by constructing a 3.5 to 5 MHz 2-D array from multilayer PZT.
The most immediate application for 2-D arrays is cardiac volumetric imaging. Successful multiplayer 2-D arrays would be drop-in replacement for current 2-D array technology. Markets for real time volumetric scanning also exist in radiology and obstetrics where slow 3-D ultrasound scanning is of limited value.
