Energy Scavenging for Wireless Sensor Networks: with Special Focus on Vibrations

1 Introduction. - 1. Energy Storage. - 2. Power Distribution. - 3. Power scavenging. - 4. Summary of potential power sources. - 5. Overview of Vibration-to-Electricity Conversion Research. - 2 Vibration Sources and Conversion Model. - 1. Types of Vibrations Considered. - 2. Characteristics of Vibrations Measured. - 3. Generic Vibration-to-Electricity Conversion Model. - 4. Efficiency of Vibration-to-Electricity Conversion. - 3 Comparison of Methods. - 1. Electromagnetic (Inductive) Power Conversion. - 2. Electrostatic (Capacitive) Power Conversion. - 3. Piezoelectric Power Conversion. - 4. Comparison of Energy Density of Converters. - 5. Summary of Conversion Mechanisms. - 4 Piezoelectric Converter Design. - 1. Basic Design Configuration. - 2. Material Selection. - 3. Analytical Model for Piezoelectric Generators. - 4. Discussion of Analytical Model for Piezoelectric Generators. - 5. Initial Prototype and Model Verification. - 6. Design Optimization. - 7. Analytical Model Adjusted for a Capacitive Load. - 8. Discussion of Analytical Model Changes for Capacitive Load. - 9. Optimization for a Capacitive Load. - 10. Conclusions. - 5 Piezoelectric Converter Test Results. - 1. Implementation of Optimized Converters. - 2. Resistive load tests. - 3. Discussion of resistive load tests. - 4. Capacitive load tests. - 5. Discussion of capacitive load test. - 6. Results from testing with a custom designed RF transceiver. - 7. Discussion of results from custom RF transceiver test. - 8. Results from test of complete wireless sensor node. - 9. Discussion of results from complete wireless sensor node. - 10. Conclusions. - 6 Electrostatic Converter Design. - 1. Explanation of concept and principle of operation. - 2. Electrostatic Conversion Model. - 3. Exploration of design concepts and device specific models. - 4. Comparison of design concepts. - 5. Design Optimization. - 6. Flexure design. - 7. Discussion of design and conclusions. - 7 Fabrication of Electrostatic Converters. - 1. Choice of process and wafer technology. - 2. Basic process flow. - 3. Specific processes used. - 4. Conclusions. - 8 Electrostatic Converter Test Results. - 1. Macro-scale prototype and results. - 2. Results from fluidic self-assembly process prototypes. - 3. Results from integrated process prototypes. - 4. Results from simplified custom process prototypes. - 5. Discussion of Results and Conclusions. - 9 Conclusions. - 1. Justification for focus on vibrations as a power source. - 2. Piezoelectric vibration to electricity converters. - 3. Design considerations for piezoelectric converters. - 4. Electrostatic vibration to electricity converters. - 5. Design considerations for electrostatic converters. - 6. Summary of conclusions. - 7. Recommendations for future work. - Acknowledgments. - Appendix A: Analytical Model of a Piezoelectric Generator. - 1. Geometric terms for bimorph mounted as a cantilever. - 2. Basic dynamic model of piezoelectric generator. - 3. Expressions of interest from basic dynamic model. - 4. Alterations to the basic dynamic model. - Appendix B: Analytical Model of an Electrostatic Generator. - 1. Derivation of electrical and geometric expressions. - 2. Derivation of mechanical dynamics and electrostatic forces. - 3. Simulation of the in-plane gap closing converter. - References.