As the world faces an energy crisis with depleting fossil fuel reserves, alternate energy sources are being researched ever more seriously. In addition to renewable energy sources, energy recycling and energy scavenging technologies are also gaining importance. Technologies are being developed to scavenge energy from ambient sources such as vibration, radio frequency and low grade waste heat, etc. Waste heat is the most common form of wasted energy and is the greatest potential source of energy scavenging. Pyroelectricity is the property of some materials to change the surface charge distribution with the change in temperature. These materials produce current as temperature varies in them and can be utilized to convert thermal energy to electrical energy. In this work a novel approach to vary temperature in pyroelectric material to convert energy has been investigated. Microelectromechanical Systems or MEMS is the new technology trend that takes advantage of unique physical properties at micro scale to create mechanical systems with electrical interface using available microelectronic fabrication techniques. MEMS can accomplish functionalities that are otherwise impossible or inefficient with macroscale technologies. The energy harvesting device modeled and developed for this work takes full benefit of MEMS technology to cycle temperature in an embedded pyroelectric material to convert thermal energy from low grade waste heat to electrical energy. Use of MEMS enables improved performance and efficiency and overcomes problems plaguing previous attempts at pyroelectric energy conversion. A Numerical model provides accurate prediction of MEMS performance and sets design criteria, while physics based analytical model simplifies design steps. A SPICE model of the MEMS device incorporates electrical conversion and enables electrical interfacing for current extraction and energy storage. Experimental results provide practical implementation steps towards of the modeled device. Under ideal condition the proposed device promises to generate energy density of 400 W/L.

This book presents device design, layout design, FEM analysis, device fabrication, and packaging and testing of MEMS-based piezoelectric vibration energy harvesters. It serves as a complete guide from design, FEM, and fabrication to characterization. Each chapter of this volume illustrates key insight technologies through images. The book showcases different technologies for energy harvesting and the importance of energy harvesting in wireless sensor networks. The design, simulation, and comparison of three types of structures – single beam cantilever structure, cantilever array structure, and guided beam structure have also been reported in one of the chapters. In this volume, an elaborate characterization of two-beam and four-beam fabricated devices has been carried out. This characterization includes structural, material, morphological, topological, dynamic, and electrical characterization of the device. The volume is very concise, easy to understand, and contains colored images to understand the details of each process.

Seeking renewable and clean energies is essential for releasing the heavy reliance on mineral-based energy and remedying the threat of global warming to our environment. In the last decade, explosive growth in research and development efforts devoted to microelectromechanical systems (MEMS) technology and nanowires-related nanotechnology have paved a great foundation for new mechanisms of harvesting mechanical energy at the micro/nano-meter scale. MEMS-based inertial sensors have been the enabler for numerous applications associated with smart phones, tablets, and mobile electronics. This is a valuable reference for all those faced with the challenging problems created by the ever-increasing interest in MEMS and nanotechnology-based energy harvesters and their applications. This book presents fundamental physics, theoretical design, and method of modeling for four mainstream energy harvesting mechanisms -- piezoelectric, electromagnetic, electrostatic, and triboelectric. Readers are provided with a comprehensive technical review and historical view of each mechanism. The authors also present current challenges in energy harvesting technology, technical reviews, design requirements, case studies, along with unique and representative examples of energy harvester applications.

Microelectromechanical system (MEMS) vibration based energy harvesters have become significantly popular due to the growing demand of wireless sensor networks which need miniature, portable, long lasting and easily recharged sources of power. Usage of hazardous batteries is an unacceptable solution to power up the densely populated nodes due to their bulky sizes and high battery replacement cost. Piezoelectric devices are the perfect candidate for implementation in micro generators as they are easily fabricated, are silicon compatible and demonstrate high efficiencies for mechanical to electrical energy conversion. This work presents the design, simulation and fabrication of MEMS piezoelectric energy harvesters. The energy harvester was formed using Aluminium doped Zinc Oxide (AZO) cantilever beams with either Aluminium or Steel contacts. FEM simulation analysis was done to obtain the resonance frequency that provides maximum displacement of vibration and maximum output power. AZO/Steel and Al/AZO/Al/Si structures were successfully simulated, fabricated and experimentally measured. The fabricated AZO/Steel beam produced 4.2 Vs/m2 at the resonant frequency of 137.157 Hz. The Al/AZO/Al/Si beam operates at higher frequencies where it produced 3.2 V AC output voltages at resonance frequencies of 8.026 MHz. The proposed designs can be positioned on a gas turbine in power plant where at a critical vibration pattern it will generate power to activate a wireless sensor to caution for maintenance.

This book presents device design, layout design, FEM analysis, device fabrication, and packaging and testing of MEMS-based piezoelectric vibration energy harvesters. It serves as a complete guide from design, FEM, and fabrication to characterization. Each chapter of this volume illustrates key insight technologies through images. The book showcases different technologies for energy harvesting and the importance of energy harvesting in wireless sensor networks. The design, simulation, and comparison of three types of structures - single beam cantilever structure, cantilever array structure, and guided beam structure have also been reported in one of the chapters. In this volume, an elaborate characterization of two-beam and four-beam fabricated devices has been carried out. This characterization includes structural, material, morphological, topological, dynamic, and electrical characterization of the device. The volume is very concise, easy to understand, and contains colored images to understand the details of each process. .

The transformation of vibrations into electric energy through the use of piezoelectric devices is an exciting and rapidly developing area of research with a widening range of applications constantly materialising. With Piezoelectric Energy Harvesting, world-leading researchers provide a timely and comprehensive coverage of the electromechanical modelling and applications of piezoelectric energy harvesters. They present principal modelling approaches, synthesizing fundamental material related to mechanical, aerospace, civil, electrical and materials engineering disciplines for vibration-based energy harvesting using piezoelectric transduction. Piezoelectric Energy Harvesting provides the first comprehensive treatment of distributed-parameter electromechanical modelling for piezoelectric energy harvesting with extensive case studies including experimental validations, and is the first book to address modelling of various forms of excitation in piezoelectric energy harvesting, ranging from airflow excitation to moving loads, thus ensuring its relevance to engineers in fields as disparate as aerospace engineering and civil engineering. Coverage includes: Analytical and approximate analytical distributed-parameter electromechanical models with illustrative theoretical case studies as well as extensive experimental validations Several problems of piezoelectric energy harvesting ranging from simple harmonic excitation to random vibrations Details of introducing and modelling piezoelectric coupling for various problems Modelling and exploiting nonlinear dynamics for performance enhancement, supported with experimental verifications Applications ranging from moving load excitation of slender bridges to airflow excitation of aeroelastic sections A review of standard nonlinear energy harvesting circuits with modelling aspects.

The power consumption of electronic devices reduces as the size of these devices shrinks [1]. Today most portable and wearable devices are still powered by batteries. Researchers have been considering various renewable energy sources include solar, wind, tidal, and mechanical vibrations [1]. The application demands the electronic devices being used in any weather conditions, anytime, and anywhere [1]. Mechanical vibrations are abundantly available in structures such as bridges, machinery, engines, and aircraft. Hence, several researchers have been developing self-powered MEMS (Microelectromechanical Systems): energy harvesters which are made of piezoelectric materials or magnetostrictive materials to provide power for low power electric devices at the mW or μW level using mechanical vibrations [1] [2].All piezoelectric materials and magnetostrictive materials have a Curie temperature. When the operating temperature is higher than the Curie temperature, piezoelectric and magnetoelectric materials lose the ability to generate electric power from mechanical vibration or magnetic fields in an environment [2] as the aligned electric and magnetic dipole moments become disordered by the thermal disturbance. The Curie temperature of the piezoelectric materials and magnetoelectric (ME) materials can be as high as 40 ~ 180 °C for the PZT based piezoelectric materials and up to 680 °C for Fe based magnetostrictive materials [2]. Given the fact that the Curie temperature of piezoelectric and magnetoelectric materials is much higher than the normal operating temperature range of batteries, composite piezoelectric and magnetoelectric energy harvesters are more suitable to operate in extreme environments in terms of wider operating temperature range.To answer the question of how to harvest energy from a broad range of mechanical vibrations in an environment, we have developed multiple stages of the research proposal to address the challenges in designing various multimodal energy harvester devices. These designs include piezoelectric harvesters through a multi-beam approach, a one-piece trapezoidal approach, and a two-piece trapezoidal approach using our composite piezoelectric material. Full-width half-maximum (FWHM) bandwidth is one of the methods to benchmark the vibration bandwidth of our piezoelectric and magnetoelectric (ME) vibration energy harvesters (VEH). Our piezoelectric and magnetoelectric (ME) VEH models are simulated using COMSOL Multiphysics software. COMSOL Multiphysics is a commercial finite element analysis computer simulation software that specializes in solving two or more coupled multi-physics problems and is widely used in engineering fields, research & product development, and academic communities. We expanded our research from a simple rectangular bimorph model to the multi-beam model and nonlinear models, and we demonstrate the wider band of the device. We further developed nonlinear shapes such as the trapezoids to investigate the frequency bandwidth of the device. The one-piece trapezoidal model was expanded to a two-piece trapezoidal beam harvester model to demonstrate that the two-piece trapezoidal piezoelectric cantilever can achieve a broader vibration frequency response. The two-piece trapezoidal piezoelectric composite beam design resulted in a broader bandwidth of 5.6 Hz while generating a maximum power density of 16.81 mW/cm3, whereas the one-piece trapezoidal beam generated a maximum power density 10.37 mW/cm3 with a bandwidth 2.9 Hz in our previous work [3] [4]. These results helped us to design for broader band piezoelectric and ME energy harvesters with higher electric power density. For single ME rectangle energy harvesters, the peak electric power reaches 8.99 mW and peak electric power density at 192 mW/cm3 via the optimal resistor of 0.5 MΩ. For the one-piece trapezoidal ME energy harvesters, we saw the peak electric power reaching 37.1 mW and peak electric power density of 56.2 mW/cm3 with an optimal resistance of 0.013 MΩ. In this work, we have advanced our research from composite piezoelectric beam models to novel trapezoidal magnetoelectric composite beam designs for harvesting not only vibration energy but also magnetic energy from the surrounding environment.