Some years ago, silicon-based mechanical sensors, like pressure sensors, accelerometers and gyroscopes, started their successful advance. Every year, hundreds of millions of these devices are sold, mainly for medical and automotive applications. The airbag sensor on which research already started several decades ago at Stanford University can be found in every new car and has saved already numerous lives. Pressure sensors are also used in modern electronic blood pressure equipment. Many other mechanical sensors, mostly invisible to the public, perform useful functions in countless industrial and consumer products.

The underlying physics and technology of silicon-based mechanical sensors is rather complex and is treated in numerous publications scattered throughout the literature. Therefore, a clear need existed for a handbook that thoroughly and systematically reviews the present basic knowledge on these devices.

After a short introduction, Professor Bao discusses the main issues relevant to silicon-based mechanical sensors. First a thorough treatment of stress and strain in diaphragms and beams is presented. Next, vibration of mechanical structures is illuminated, followed by a chapter on air damping. These basic chapters are then succeeded by chapters in which capacitive and piezoresistive sensing techniques are amply discussed. The book concludes with chapters on commercially available pressure sensors, accelerometers and resonant sensors in which the above principles are applied.

Everybody, involved in designing silicon-based mechanical sensors, will find a wealth of useful information in the book, assisting the designer in obtaining highly optimized devices.

This authoritative new book focuses on recent developments in the instrumentation for sending voltages and currents. It covers new trends and challenges in the field, such as measurements of biocurrents, the increased speed of the components for data taking, testing of computers and integrated circuits where the measurement of rapid voltage and current variations on a very small geometrical scale is necessary. The first chapter concentrates on recent methods to sense voltages and currents, while the rest of the book investigates the applied side, covering for instance electrical power and energy measurements. The main purpose of this volume is to illustrate commonly employed techniques rather than track the scientific evolution and merits and therefore mainly covers patent literature aimed at industrial applications. It is an exciting addition, justifying the series' claim to cover state-of-the-art developments in both the applied and theoretical fields of sensors and actuators.

The measurement of voltages and currents is a common task in the field of electricity and electronics. From a technical point of view it is useful to identify schematically different steps of such a measurement. In a first step a voltage or a current is sensed, intermediate steps such as amplification, transmission and further treatment may follow to yield the result in the final step. Today in most cases microprocessors perform the final steps of such measurements. Analog-to digital converters digitise a voltage that is proportional to the value to be measured and a processor performs further computations and handles the storage and the display of the results. The prerequisite for such measurements are sensors or transducers that respond in a known way to the voltage or current to be measured. The emphasis of this book is put on recent developments of the instrumentation for sensing voltages and currents.

Aside from the general trend towards smaller, cheaper and more reliable instrumentation, new demands have arisen. New applications, like measurements of biocurrents, ask for higher sensitivities. Computers and integrated circuits pose new challenges. To exploit the increased speed of the components for data taking, suitable sensors are required. The accuracy that can be achieved depends more than ever on the first step, the acquisition of the raw data. The influence of the measurement process on the results becomes more crucial. Testing of integrated circuits themselves is a completely new application. For such tests one has to measure rapid voltage and current variations on very small geometrical scales. Here, as well as in the traditional high voltage applications, contactless measurements play an important role.

The organisation of this book is as follows: In the first chapter different methods to sense voltages and currents are described. For the sake of completeness most commonly used methods are mentioned, we concentrate, however, on those developed recently. The chapters address the subject from the side of different applications in which voltages and currents are sensed.

Since the main purpose of this publication is to illustrate commonly employed techniques rather than to track the scientific evolution and merits in particular fields, in general those publications that illustrate a particular measurement principle best have been cited. The citation of a particular reference does therefore not imply that this is the first or most pertinent publication in the respective field.