Mask-Less Direct-Writing Deposition of Lead-Free Piezoelectric Films for Microsystems

Piezoelectric films fabricated with lead-free piezoelectric inks by means of a mask-less Direct-Writing (DW) technique are presented. A lead-free piezoelectric material, K0.5Na0.5NbO3-δ (KNN), has been produced via Solid State Reaction (SSR) and Molten Citrate (MC) route in order to improve the microstructural properties of powders. The slurry composition and rheology have been optimized in order to obtain inks with physical properties compatible with the DW technique and layers with enhanced mechanical and piezoelectric properties. Experimental results obtained with pellets and films deposited on alumina substrates demonstrate the piezoelectric properties of the fabricated devices. The developed direct-writing technique will be implemented for the realization of precise patterns of piezoelectric sensors or actuators inside microsystems, without the requirement of manufacture expensive masks.