Shad Roundy - Böcker

The vast reduction in size and power consumption of CMOS circuitry has led to a large research effort based around the vision of ubiquitous networks of wireless communication nodes. The wireless devices are usually designed to run on batteries. However, as the networks increase in number and the devices decrease in size, the replacement of depleted batteries is not practical. Furthermore, a battery that is large enough to last the lifetime of the device would dominate the overall system size, and thus is not very attractive. There is clearly a need to explore alternative methods of powering these small communication nodes. This book, therefore, focuses on potential "ambient" sources of power that can be scavenged or harvested and subsequently used to run low power electronics and wireless transceivers. A wide range of potential power sources are briefly explored. Based on a comparison of these many potential sources, commonly occurring vibrations was chosen as an attractive, and little explored, power source. Models for different types of power converters using both electrostatic and piezoelectric conversion mechanisms have been developed.The models have been validated by testing prototypes driven at vibrations similar to those found in many industrial and commercial building environments. Finally, integration of a piezoelectric generator, power circuit, and custom design radio transceiver is demonstrated. Power sources are becoming a bottleneck to the widespread deployment of wireless sensor networks. This work reviews many potential alternative sources of ambient power that can be scavenged. Vibration to electricity converters are explored in great detail, and based on studies and experiments, are shown to be an attractive power source in many applications.

The vast reduction in size and power consumption of CMOS circuitry has led to a large research effort based around the vision of wireless sensor networks. The proposed networks will be comprised of thousands of small wireless nodes that operate in a multi-hop fashion, replacing long transmission distances with many low power, low cost wireless devices. The result will be the creation of an intelligent environment responding to its inhabitants and ambient conditions. Wireless devices currently being designed and built for use in such environments typically run on batteries. However, as the networks increase in number and the devices decrease in size, the replacement of depleted batteries will not be practical. The cost of replacing batteries in a few devices that make up a small network about once per year is modest. However, the cost of replacing thousands of devices in a single building annually, some of which are in areas difficult to access, is simply not practical. Another approach would be to use a battery that is large enough to last the entire lifetime of the wireless sensor device. However, a battery large enough to last the lifetime of the device would dominate the overall system size and cost, and thus is not very attractive. Alternative methods of powering the devices that will make up the wireless networks are desperately needed.