Micro Mechanical Transducers
Pressure Sensors, Accelerometers and GyroscopesEdited by
- S. Middelhoek
- Min-hang Bao, Fudan University, Shanghai, China
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.
Engineers, Researchers, Graduates and Undergraduates in the field of Micro actuators and micro systems.
Handbook of Sensors and Actuators
Hardbound, 392 Pages
Published: October 2000
- Preface. Introduction to micro mechanical transducers. Piezoresistive pressure sensors. Piezoresistive accelerometers. Capacitive sensors. Resonant sensors. Vibratory gyroscopes. Basic principles of micro mechanical transducers. References. Basic mechanics of beam and diaphragm structures. Stress and strain. Stress and strain of beam structures. Vibration frequency by energy method. Vibration frequencies of beam by differential equation method. Damped and forced vibration. Basic mechanics of diaphragms. References. Air damping. Viscous flow of a fluid. Squeeze-film air damping. Slide-film air damping. Damping in rare air. References. Electrostatic driving and capacitive sensing. Electrostatic force. Displacement of elastic structures by electrostatic force. Step and alternating driving. Capacitive sensing. Effects of electric driving on capacitive sensing. References. Piezoresistive sensing. Metal strain gauge. Piezoresistive effect of silicon. Coordinate transformation of tensors of the second rank. Coordinate transformation of piezoresistive coefficient. Piezoresistive sensing elements. Polysilicon piezoresistive sensing elements. Average piezoresistive coefficient. Design of polysilicon piezoresistive sensors. References. Piezoresistive pressure transducers. Designs with flat diaphragms. Pressure transducers with sculptured diaphragm structure. Design of polysilicon pressure transducer. Offset voltage and temperature coefficient of offset. Temperature coefficient of sensitivity. Nonlinearity. Calibration of pressure transducers. References. Piezoresistive accelerometers. Cantilever beam accelerometers. Quad-beam accelerometer. Twin-mass accelerometer. Lateral accelerometers. References. Capacitive pressure transducers and accelerometers. Capacitive pressure transducers. Open loop capacitive accelerometers. Force-balanced accelerometers. Thermo-mechanical noise of mechanical structures. References. Resonant sensors and vibratory gyroscopes. Resonant pressure transducers. Resonant accelerometers. Vibratory gyroscopes. References. Subject Index.