Surface Acoustic Wave Based Magnetic Sensors

Surface Acoustic Wave Based Magnetic Sensors.

Acoustics is a mature field which enjoys a never ending youth. New developments are induced by either the search for a better understanding, or by technological innovations. Micro-fabrication techniques introduced a whole new class of microdevices, which exploit acoustic waves for various tasks, and in particular for information processing and for sensing purposes. Performance improvements are achievable by better modelling tools, able to deal with more complex configurations, and by more refined techniques of fabrication and of integration in technological systems, like wireless communications. Several chapters of this book deal with modelling and fabrication techniques for microdevices, including unconventional phenomena and configurations. But this is far from exhausting the research lines in acoustics. Theoretical analyses and modelling techniques are presented, for phenomena ranging from the detection of cracks to the acoustics of the oceans. Measurement methods are also discussed, which probe by acoustic waves the properties of widely different systems.

The last few decades have seen tremendous growth in the area of magnetic sensor technologies. The field has grown from simple micro-machined silicon based devices to more complex integrated microsystems combining high performance transducers as well as wireless interfaces. However, almost all of these devices operate with a complex mechanism while simultaneously being externally powered as well as expensive. Thus, there arises a deep need to develop a magnetic sensor that overcomes the challenges. This research work focused on the development of surface acoustic wave (SAW) sensors for the detection of magnetic field. Owing to the possibility of wireless interrogation, SAW devices of the resonator configuration have been considered in this study. The first part of our work aims to address the physics and interaction between the acoustic waves and magnetostrictive layers when subjected to a magnetic field. We investigated SAW resonators using LiNbO3 as the substrate and multi-layered [TbCo2/FeCo] as the electrode and sensitive material. We studied and showed the role of the shape effect in magnetism arising from the electrode geometry. A model experimental set-up was developed to demonstrate an application of the fabricated device as a sensor for detection of current along a cable. Subsequently, we developed a device that is self-compensated for the effects of temperature on the resonance frequency. The multi-layered sensor was based on ST-cut Quartz as the substrate whose positive temperature coefficient of frequency (TCF) was compensated for by the negative TCF of ZnO and CoFeB. Finally, we combine our understandings of the shape effects in magnetism and the multi-layered TCF compensated SAW structure to develop a device that is not only compensated for the effects of temperature on the resonance frequency but also on the magnetic anisotropy. In addition, this structure also presents the possibility of a proof-of-concept multi-sensory device because along with the temperature compensated resonance peak, there exist other resonances which are highly sensitive to any change in the temperature while at the same time immune to magnetic field.

Surface acoustic wave (SAW) devices are widely used in mobile communications, a rapidly evolving market. This book gives an overview on the latest SAW technologies with an emphasis on the design and simulation of devices, such as resonator-based devices employing the SH-type leaky SAW.

The book Smart Sensors and MEMS provides an unique collection of contributions on latest achievements in sensors area and technologies that have made by eleven internationally recognized leading experts from Czech Republic, Germany, Italy, Israel, Portugal, Switzerland, Ukraine and USA during the NATO Advanced Study Institute (ASI) in Povoa de Varzim, Portugal, from 8 to 19 September 2003. The aims of this volume are to disseminate wider and in-depth theoretical and practical knowledge about smart sensors and its applications, to create a clear consciousness about the effectiveness of MEMS technologies, advanced signal processing and conversion methods, to stimulate the theoretical and applied research in these areas, and promote the practical using of these techniques in the industry. With that in mind, a broad range of physical, chemical and biosensors design principles, technologies and applications were included in the book. It is a first attempt to describe in the same book different physical, chemical, biological sensors and MEMS technologies suitable for smart sensors creation. The book presents the state-of-the-art and gives an excellent opportunity to provide a systematic, in-depth treatment of the new and rapidly developing field of smart sensors and MEMS. The volume is an excellent guide for practicing engineers, researchers and students interested in this crucial aspect of actual smart sensor design.

Written by an interdisciplinary group of experts from both industry and academia, Acoustic Wave Sensors provides an in-depth look at the current state of acoustic wave devices and the scope of their use in chemical, biochemical, and physical measurements, as well as in engineering applications. Because of the inherent interdisciplinary applications of these devices, this book will be useful for the chemist and biochemist interested in the use and development ofthese sensors for specific applications; the electrical engineer involved in the design and improvement of these devices; the chemical engineer and the biotechnologist interested in using these devices for process monitoring and control; and the sensor community at large. Provides in-depth comparison and analyses of different types of acoustic wave devices Discusses operating principles and design considerations Includes table of relevant material constants for quick reference Presents an extensive review of current uses of these devices for chemical, biochemical, and physical measurements, and engineering applications

This completely updated second edition of an Artech House classic covers industrial applications and space and biomedical applications of magnetic sensors and magnetometers. With the advancement of smart grids, renewable energy resources, and electric vehicles, the importance of electric current sensors increased, and the book has been updated to reflect these changes. Integrated fluxgate single-chip magnetometers are presented. GMR sensors in the automotive market, especially for end-of-shaft angular sensors, are included, as well as Linear TMR sensors. Vertical Hall sensors and sensors with integrated ferromagnetic concentrators are two competing technologies, which both brought 3-axial single-chip Hall ICs, are considered. Digital fluxgate magnetometers for both satellite and ground-based applications are discussed. All-optical resonant magnetometes, based on the Coherent Population Trapping effect, has reached approval in space, and is covered in this new edition of the book. Whether you're an expert or new to the field, this unique resource offers you a thorough overview of the principles and design of magnetic sensors and magnetometers, as well as guidance in applying specific devices in the real world. The book covers both multi-channel and gradiometric magnetometer systems, special problems such as cross-talk and crossfield sensitivity, and comparisons between different sensors and magnetometers with respect to various application areas. Miniaturization and the use of new materials in magnetic sensors are also discussed. A comprehensive list of references to journal articles, books, proceedings and webpages helps you find additional information quickly.

The manipulation of cells and microparticles within microfluidic systems using external forces is valuable for many microscale analytical and bioanalytical applications. Acoustofluidics is the ultrasound-based external forcing of microparticles with microfluidic systems. It has gained much interest because it allows for the simple label-free separation of microparticles based on their mechanical properties without affecting the microparticles themselves. Microscale Acoustofluidics provides an introduction to the field providing the background to the fundamental physics including chapters on governing equations in microfluidics and perturbation theory and ultrasound resonances, acoustic radiation force on small particles, continuum mechanics for ultrasonic particle manipulation, and piezoelectricity and application to the excitation of acoustic fields for ultrasonic particle manipulation. The book also provides information on the design and characterization of ultrasonic particle manipulation devices as well as applications in acoustic trapping and immunoassays. Written by leading experts in the field, the book will appeal to postgraduate students and researchers interested in microfluidics and lab-on-a-chip applications.

This book concerns the design, operation and application of devices capable of generating acoustic waves in the ultrasonic frequency range. It emphasizes the study of chemical and/or biochemical systems imposed on the surface of such devices, whether operated in the gas- or liquid-phase, i.e. on acoustic wave chemical and biological sensors. It focuses on devices that employ acoustic waves launched and received on the same surface. It touches upon such diverse areas as acoustic wave physics, applied mathematics, chemistry, electronics, fluid mechanics, materials science and polymer science.