Western Michigan University ScholarWorks at WMU Dissertations Graduate College 8-2007 Wireless Passive Surface Acoustic Wave (SAW) Sensing System Sridevi Krishnamurthy Western Michigan University Follow this and additional works at: https://scholarworks.wmich.edu/dissertations Part of the Physics Commons Recommended Citation Krishnamurthy, Sridevi, "Wireless Passive Surface Acoustic Wave (SAW) Sensing System" (2007). Dissertations. 884. https://scholarworks.wmich.edu/dissertations/884 This Dissertation-Open Access is brought to you for free and open access by the Graduate College at ScholarWorks at WMU. It has been accepted for inclusion in Dissertations by an authorized administrator of ScholarWorks at WMU. For more information, please contact [email protected]. WIRELESS PASSIVE SURFACE ACOUSTIC WAVE (SAW) SENSING SYSTEM by Sridevi Krishnamurthy A Dissertation Submitted to the Faculty of The Graduate College in partial fulfillment of the requirements for the Degree of Doctor of Philosophy Department of Electrical and Computer Engineering Dr. Massood Z. Atashbar, Advisor Western Michigan University Kalamazoo, Michigan August 2007 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. WIRELESS PASSIVE SURFACE ACOUSTIC WAVE (SAW) SENSING SYSTEM Sridevi Krishnamurthy, Ph.D. Western Michigan University, 2007 Due to their small size and ruggedness, Surface Acoustic Wave (SAW) devices have been widely used as part of wireless sensing or identification system especially in inaccessible and inhospitable environments. In addition, SAW devices find widespread applications as filters in communication systems and also as physical, chemical and bio-sensors and ID tags. The passive wireless SAW sensing system mainly consists of a passive SAW sensor and an interrogation unit which sends a burst signal to the SAW sensor and processes the sensor response. The main objectives of this work were designing, prototyping and fabricating the interrogation unit on a PCB and also designing modeling, simulating and fabricating SAW devices. Significant results obtained from the burst transceiver and simulation as well as measurement results of SAW devices will be presented together with some of the challenges faced. The interrogation unit is a burst transceiver operating in the Industrial, Scientific and Medical (ISM) band at 433 MEIz. The prototype was built using connectorized modules and manufacturer demonstration boards. Once the prototype burst transceiver was tested for its functionality, a miniaturized version was designed and fabricated on a PCB. The PCB layout was prepared using FreePCB™ software Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. and manufactured at Cirexx International, CA. Both the prototype and the PCB burst transceiver is characterized using a cascaded gain and noise figure analysis performed for both the transmit and the receive sections. SAW delay lines and resonators operating at 100 MHz were first designed and then fabricated at the University of Michigan’s Micro/Nano fabrication facility in Ann Arbor, MI. Simulation of the frequency response of SAW devices were performed in MATLAB™, PSpice Capture™ and CoventorWare™. The design aspects of SAW devices and details of modeling the SAW devices in each of the above software packages are presented. Simulation results obtained from all the three software packages are compared with measured responses and the relative merits and demerits of each method will be presented. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 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Copyright by Sridevi Krishnamurthy 2007 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. ACKNOWLEDGEMENTS I would like to express my deepest appreciation and gratitude to my dissertation Committee Chair and advisor Dr. Massood Atashbar for his continuous guidance throughout my dissertation work and his constant support and encouragement. I would like to thank my advisor Dr. Bradley Bazuin for this invaluable guidance and persistent help every step of the way. I would like to thank Dr. John Gesink, ECE Chair for agreeing to be on my Committee and being kind enough to patiently read through my dissertation. Special thanks are due to Dr. Azim Houshyar for being on my Committee and reading through my dissertation. I would like to thank the Graduate College at Western Michigan University and the National Science Foundation for their financial support. In addition, I would like to thank Mr. David Florida of the Department of Electrical and Computer Engineering and Mr. Glenn Hall of the Department of Mechanical and Aeronautical Engineering for providing technical support throughout the course of this dissertation work. I would also like express my gratitude to Ms. Janet Liebendorfer and Ms. Sheryl Todd for their assistance with all the associated paper work. Special thanks to Dr. Karlis Kaugars and the CAE staff for being kind enough to let me run simulations on their computers night after night. I would like to thank my parents and sister for all the sacrifices they have made over the years in order to provide me the finest education possible. Without their support, this dissertation work would have been impossible. I also wish to thank my in-laws for their constant support and encouragement and for truly believing in me. I would like to thank my friend Mr. Srikanth Singamaneni for being a great source of inspiration and motivation throughout course of my dissertation. I would ii Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Acknowledgements-Continued also like to thank my dear friend Ms. Aarthi Sridharan for always being there and encouraging me in all my endeavours. Last but not least, this section would be incomplete without expressing my heartfelt thanks and appreciation to my husband for all the sacrifices that he has made and for constantly encouraging me. Without his support, I would not have been able to complete this dissertation work. Sridevi Krishnamurthy iii Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. TABLE OF CONTENTS ACKNOWLEDGEMENTS......................................................................................... ii LIST OF TABLES......................................................................................................... ix LIST OF FIGURES ..................................................................................................... x CHAPTER I. INTRODUCTION ....................................................................................... 1 1.1 Background ......................................................................................... 1 1.2 Motivation ........................................................................................ 4 1.3 Author’s contributions ....................................................................... 6 1.4 Organization of the dissertation ........................................................ 7 II. INTRODUCTION TO SURFACE ACOUSTIC WAVE (SAW) SENSORS .................................................................................. 8 2.1 Introduction ......................................................................................... 8 2.2 SAW device configurations .............................................................. 12 2.2.1 SAW delay line ...................................................................... 12 2.2.2 One-port SAW resonator ...................................................... 13 2.2.3 Two-port SAW resonator .................................................... 14 2.3 Acoustic wave sensors ....................................................................... 15 2.3.1 Thickness shear mode based sensor ...................................... 16 2.3.2 Rayleigh mode SAW based sensor ........ 17 2.3.3 Shear horizontal SAW based sensor ................................... 18 2.3.4 Shear horizontal acoustic plate mode based sensor .......... 19 iv Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Table of Contents-Continued CHAPTER 2.3.5 Lamb wave based sensor ...................................................... 20 2.3.6 Love wave based sensor ................................ 22 2.4 Summary of sensing mechanisms ................................................... 23 2.4.1 Temperature ..........................................................................