Sensors

Sensors are the eyes or/and ears of an intelligent system, such as UAV, AGV and robots. With the development of material, signal processing, and multidisciplinary interactions, more and more smart sensors are proposed and fabricated under increasing demands for homes, the industry, and military fields. Networks of sensors will be able to enhance the ability to obtain huge amounts of information (big data) and improve precision, which also mirrors the developmental tendency of modern sensors.

The low cost and direct digital output of CMOS smart temperature sensors are important advantages compared to conventional temperature sensors. This book addresses the main problem that nevertheless prevents widespread - plication of CMOS smart temperature sensors: their relatively poor absolute accuracy. Several new techniques are introduced to improve this accuracy. The effectiveness of these techniques is demonstrated using three prototypes. ? The ?nal prototype achieves an inaccuracy of±0.1 C over the military t- perature range, which is a signi?cant improvement in the state of the art. Since smart temperature sensors have been the subject of academic and industrial research for more than two decades, an overview of existing knowledge and techniques is also provided throughout the book. Inthisintroductorychapter,themotivationandobjectivesofthisworkare- scribed.

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.

This book describes some devices that are commonly identified as tactile or force sensors. This is achieved with different degrees of detail through the description of different approaches to this type of sensors. This book are more focused on information readout and processing: as materials, micro and sub-micro sensors are available, wireless transmission and processing of the sensorial information, as well as some innovative methodologies for obtaining and interpreting tactile information are also strongly evolving.

This book is about devices commonly called sensors. The scope of this book is rather broad covering many different designs. Some are well known, but describing them is still useful for students and those who look for a convenient reference. It is the author's intention to present a comprehensive and up-to-date account of the theory (physical principles), design, and practical implementations of various sensors for scientific, industrial, and consumer applications.

In recent years, technological advances have resulted in the rapid development of a new exciting research direction –- the interdisciplinary use of sensors for data collection, systems analysis, and monitoring. Application areas include environmental monitoring, military surveillance, computational neuroscience, seismic detection, and many more. Among the research areas considered, sensor networks represent a very active area, as well as work on problems such as sensor networks, sensor network localization, and network design. They are also related to optimization problems that have multiple applications and require interdisciplinary techniques from several fields. Additionally, neuroscientists use sensors to collect data during tests which record brain activity. These highly calibrated sensors require precision engineering techniques play an important role in analyzing and integrating large datasets.

Autonomous sensors transmit data and power their electronics without using cables. They can be found in e.g. wireless sensor networks (WSNs) or remote acquisition systems. Although primary batteries provide a simple design for powering autonomous sensors, they present several limitations such as limited capacity and power density, and difficulty in predicting their condition and state of charge. An alternative is to extract energy from the ambient (energy harvesting). However, the reduced dimensions of most autonomous sensors lead to a low level of available power from the energy transducer. Thus, efficient methods and circuits to manage and gather the energy are a must.

This book is about devices commonly called sensors. The scope of this book is rather broad covering many different designs.