Smart systems can both sense a change in the environment and respond to that change in a useful way. Central to the operation of smart systems are materials that can serve as sensors and actuators: shape-memory, piezoelectric, and magnetostrictive materials, to name but a few. This book addresses materials issues related to smart systems including: shape-memory alloys and their applications; magnetostrictive materials and their applications; piezoelectric sensors and actuators; electrically/magnetically actuated materials; thin-film sensors; optical systems; damping materials; novel materials and mechanisms; and characterization and modelling. Papers on alternative sensing and actuating mechanisms are featured. Materials for gas sensors, electrochromic devices, magnetorheological fluids and thermoplastic elastomers are described.