Fabrication of a (K,Na)NbO3-based lead-free 1-3 piezocomposite for high-sensitivity ultrasonic transducers application

Abstract

Ultrasonic imaging is a well-established powerful medical diagnosis tool at present. However, commercial ultrasonic transducers are commonly made of toxic lead-based piezoelectric materials. Thus, it is vital to develop lead-free alternatives with satisfactory performance. This study presents the development of a phase boundary-engineered (K,Na)NbO3-based lead-free 1-3 piezocomposite and its application on high-sensitivity ultrasonic imaging transducers. A modified dice-and-fill technique was used to manufacture the microscale piezocomposite, by which the ceramic pillars were miniaturized to a width of 55 μm with a kerf of 15 μm. Improved acoustic and electrical properties were obtained in the new piezocomposite, and ultrasonic imaging transducers were further designed and fabricated based on the composite. The fabricated transducers exhibit enhanced performance with a high center frequency (16 MHz), a broad bandwidth (83%), and a very low insertion loss (9.8 dB), outperforming state-of-the-art transducers based on other lead-free materials. Imaging capability of the transducers was evaluated via ex vivo imaging of a porcine eyeball, indicating that this lead-free piezocomposite has many attractive properties in developing environment-friendly high-sensitivity ultrasonic devices for biomedical imaging applications.