Microsensors, microelectromechanical systems (MEMS), and electronics for smart structures and systems

Abstract

The technology referred to by the terms `microelectromechanical systems' (MEMS), `interdigital transducers' (IDTs), and `smart systems' is a multidisciplinary one which has generated a great deal of interest in the chemical, mechanical, electrical engineering, medical, materials science, and food science communities in recent years. The term `smart system' refers to a device or an array of devices that can sense changes in its environment and makes a useful or optimal response by changing its material properties, geometry, or mechanical or electromagnetic response. Both the sensor and actuator functions with the appropriate feedback must be integrated, and comprise the `brain' of the material. The materials belonging to this category include a range of artificial materials, from optically active or chiral polymers to multifunctional polymers, carbon nanotubes, piezoelectrics, ferroelectrics, and other active ceramics. The miniaturization of sensors and subsequently that of the MEMS incorporating the sensors, actuators, and electronic circuitry for signal processing and control feedback have been made possible by advances in technologies originating in the semiconductor industry, and the emerging field has grown rapidly during the past ten years. Recently, microstereolithography has revolutionized the MEMS industry through multifunctional polymeric materials incorporating organic thin-film transistors with three-dimensional MEMS which is not possible with silicon processing.