Self-focused high frequency ultrasonic transducers based on ZnO piezoelectric films

A micromachined self-focusing high frequency ultrasonic transducer was fabricated with a 13 mu m thick ZnO film deposited on a silicon substrate by sputtering. X-ray diffraction shows that the film has a high (002) orientation. The element aperture size of the transducer was 2.5 mm, and the fundamental resonant frequency was designed to be over 200 MHz with approximately 28% bandwidth through only one matching layer. Experimental results show that this type of focused high frequency ultrasound device may have potential for cellular microstructure imaging and skin cancer detection. (c) 2007 American Institute of Physics.