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Smart Material Systems and MEMS - Vijay K. Varadan Part 4

Tham khảo tài liệu 'smart material systems and mems - vijay k. varadan part 4', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 84 Smart Material Systems and MEMS Electromechanical Systems MEMS 2000 IEEE Piscataway NJ USA pp. 142-147 2000 . 13. W. Riethmuller and W. Benecke Thermally excited silicon microactuators IEEE Transactions Electron Devices 35 758-763 1988 . 14. Q.A. Huang and N.K.S. Lee Analysis and design of polysilicon thermal flexure actuator Journal of Micromechanical and Microengineering 9 64-70 1999 . 15. G. Sun and C.T. Sun Bending of shape-memory alloy-reinforced composite beam Journal of Materials Science 30 5750-5754 1995 . 16. D. Wood J.S. Burdess and A.J. Harris Actuators and their mechanisms in microengineering in Proceedings of the Colloquium on Actuator Technology Current Practice and New Developments No. 110 IEE London UK pp. 7 1-7 3 1996 . 5 Design Examples for Sensors and Actuators 5.1 INTRODUCTION The principles of several sensors and actuators have been discussed in Chapters 3 and 4. Several of these devices are employed in numerous applications in civil military aerospace and biological areas as will be demonstrated in Part 4 of this text. This chapter is intended to provide the basic understanding of the design of some of these sensors and actuators. Examples of sensors presented here include the piezoelectric and piezoresistive types. A chemical sensor based on the surface accoustic wave SAW principles is described. A fiber-optic gyroscope represents the optical segment of sensors in this chapter. In addition the design of microvalves and pumps required in several biomedical applications is also included here. 5.2 PIEZOELECTRIC SENSORS Lead zirconate titanate commonly known by the acronym PZT is arguably the most widely used component in smart systems. The importance of this material comes from the fact that it exhibits significant piezoelectric properties. Piezoelectricity refers to the phenomenon in which forces applied to a slab of a material result in the generation of electrical charges on the surfaces of the slab. This is due to the distribution of .