A micromachined self-focusing high frequency ultrasonic transducer was fabricated with a $13\mu \mathrm{m}$ 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 $2.5\mathrm{mm}$ , and the fundamental resonant frequency was designed to be over $200\mathrm{MHz}$ 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.

This paper describes a piezoelectric micropump built on a dome-shaped diaphragm with one-way parylene valves. The micropump uses piezoelectric ZnO film (less than 10 /spl mu/m thick) to actuate a parylene dome diaphragm, which is fabricated with an innovative, IC-compatible process on a silicon substrate. Piezoelectric ZnO film is sputter-deposited on a parylene dome diaphragm with its C-axis oriented perpendicular to the dome surface. Two one-way check valves (made of parylene) are integrated with a piezoelectrically actuated dome diaphragm to form a multi-chip micropump. The fabricated micropump (10/spl times/10/spl times/1.6 mm/sup 3/) consumes extremely low power (i.e., 3 mW to pump 3.2 /spl mu/L/min) and shows negligible leak up to 700 Pa static differential pressure.