Microstructuring technology

Piezoelectric transducers for medical imaging and non-destructive evaluation are increasingly based on composite materials, especially 1-3 composites. The known methods to prepare such transducers and in particular the widely used dice-and-fill technique are reviewed and discussed with respect to the specific advantages and limitations. Technologies using the micro-structuring of green ceramic bodies can be combined with a photolithographic step, thus allowing parts to be manufactured with almost unlimited geometrical design. By this method, composites with annular structures, hexagonal rods, variable spacing or statistical fluctuations of the rod geometry for a better suppression of spurious modes can be realized according to the different specifications and wishes of modelling. The so-called lost mould method as the most suitable process is discussed in detail. The results obtained for 1-3 composite structures and for complete ultrasonic antennas show the potential for a new generation of optimized transducers in the frequency range ⩾5 MHz