Thick-film piezoceramics and devices

Over the past 20 years, thick-film (screen printed) technology has been shown to possess a variety of desirable characteristics, which are particularly suitable for the realisation of micro-sensors and actuators. In particular, thick-film sensors are noted for their robust, versatile, compact and inexpensive nature. This paper will describe how screen printed thick-films can be used as the basis for a variety of piezoelectric a transducers. It will be shown how the technology can be combined with MicroElectroMechanical Systems (MEMS) to generate new types of micro-engineered structure. The evolution of the technology to a successful enabling mechanism for modern-day solid state sensors is described. The paper begins with a brief overview of piezoelectric thick-films including a discussion of the main factors relating to paste formulation, characterisation and techniques for fabricating devices. There is also a description of methods for fabricating thick-films on silicon, which opens up the possibility of using thick-film technology in the field of MEMS. A number of specific sensors and actuators are described, including accelerometers, micropumps, ultrasonic motors, slip sensors for prosthetic hands, resonators, elastic wave sensors and ultrasonic separators.