Controlling the mechanical, electrical, magnetic, and optical properties of materials by advanced fabrication methods (Le. ; Molecular Beam Epitaxy and Metal-Organic Chemical Vapor Deposition) has become the new paradigm in our research era. Sensors, being the most vital part of the electronic data processing and decision making machines, stand to gain the most from engineering of the properties of materials. Microfabrication technology has already contributed significantly to the batch fabrication of micro-sensors with higher over all qualities compared to their counterparts that are fabricated using other methods. Batch fabrication of micro-sensors i) results in more uniform properties of co-fabricated devices, ii) nearly eliminates the need for characterization of individual sensors, and iii) eliminates a need for laborious alignment procedures. A less obvious benefit of using microfabrication methods is the possibility of precise control over the dimensions of the sensor. This control enables engineering of some of the properties of the material which affect the sensor's operation. There are many examples of this in the literature. Optical sensors are known to have superior properties over their counterparts that use other (i. e. ; electrostatic and magnetic) means of detection. To name a few, these advantages are: i) immunity to electromagnetic interferences, ii) higher sensitivities compared to the other types of sensors, iii) simplicity of operation principles, and iv) simplicity of overall construction.

219 8. 2 Sensors 221 8. 3 Physical Sensors 222 8. 3. 1 Electrical Sensing Means 223 8. 3. 2 Magnetic Field Methods 231 8. 3. 3 Optical Methods 232 8. 4 Chemical Sensors 241 8. 4. 1 Electrical Gas and Chemical Sensors 243 8. 4. 2 Guided-Optics Intrinsic Chemical Sensors 246 8. 4. 3 Extrinsic Chemical Sensors 250 8. 4. 4 Polymer Waveguide Chemical Sensors 251 8. 4. 5 Surface Plasmon Chemical Sensors 252 8. 4. 6 Indicator-Mediated Extrinsic Sensing 253 8. 4. 7 Optical Biosensors 256 8. 4. 8 Ultrasonic Gas and Chemical Sensors 257 8. 4. 9 Intelligent Sensors 258 8. 5 Connections/Links and Wiring 258 8. 5. 1 Optical Links 260 8. 5. 2 Requirement on the Processing Unit/Intelligence 262 8. 6 Actuators 263 8. 7 Signal Processing/Computing 264 8. 7. 1 Implicit Computation 266 8. 7. 2 Explicit Computation 267 8. 8 References 274 Subject Index 279 Micro-Actuators (Electrical, Magnetic, Thermal, Optical, Mechanical, and Chemical) It has become quite apparent that sensors and actuators are the main bottleneck of the modem information processing and control systems. Microprocessors and computers used to be the main limiting element in most information processing systems. But thanks to the enonnous progress in the microelectronics industry, most information analysis tasks can be processed in real time. The data has to be acquired by the processor in some form and processed and used to produce some useful function in the real world.

This text examines the technology behind the plethora of modern industrial and domestic technologies which incorporate micro-optics eg. CDs, cameras, automated manufacturing systems, mobile communications etc. It includes a simple but comprehensive introduction to micro-optical developments design, and an overview of fabrication and replication technology. The theoretical, practical and industrial developments in micro-scale optoelectronics continue apace in the late 1990s. In this book, a distinguished group of physicists and engineers describe the current state of research and applications in micro-optics. It provides the theoretical background and an overview of current technology, with several chapters taking a deeper look at specific recent applications and future trends. The book concentrates on diffractive and refractive micro- optical elements, such as lenses, fan-out gratings, optimized phase elements and polarisers. Sections are included on the simulation and optimization of design for micro-optics and subsequently the efficient transformation from design to real optical elements, using techniques such as e-beam writing, laser beam writing, lithography, etching and thin film deposition.

Contains useful process details, recipes, tables, charts and includes numerous device applications.

Femtosecond laser micromachining of transparent material is a powerful and versatile technology. In fact, it can be applied to several materials. It is a maskless technology that allows rapid device prototyping, has intrinsic three-dimensional capabilities and can produce both photonic and microfluidic devices. For these reasons it is ideally suited for the fabrication of complex microsystems with unprecedented functionalities. The book is mainly focused on micromachining of transparent materials which, due to the nonlinear absorption mechanism of ultrashort pulses, allows unique three-dimensional capabilities and can be exploited for the fabrication of complex microsystems with unprecedented functionalities.This book presents an overview of the state of the art of this rapidly emerging topic with contributions from leading experts in the field, ranging from principles of nonlinear material modification to fabrication techniques and applications to photonics and optofluidics.