A high-performance electromagnetic vibration energy harvester based on ring magnets with Halbach configuration

This paper proposes and studies a ring-shaped architecture with Halbach configuration for electromagnetic vibration energy harvesters. The proposed transducer consists of three ring magnets with a linear Halbach array that concentrates its magnetic field in the inner space of the mechanism where a single vertically-centered concentric coil has been located. This particular structure allows to increase the resonant mass within a fixed dimensions of the transducer and reduces the coil resistance for the same number of turns, enhancing its power generation capabilities. The ring-shaped architecture has been compared with several ring magnet arrangements, including single magnets, double-magnet arrays, and an alternative linear Halbach array, using numerical simulations to determine their influence on its performance. Consequently, this work is the first contribution to the applicability of Halbach configurations for electromagnetic vibration energy harvesters within ring-shaped architectures. Also, a geometrical optimization of the proposed transducer has been conducted, mainly as a function of the inner radius, the height, and the wire diameter of the coil, to increase its power generation. The maximum simulated output power for the optimized generator reaches 3.61 mW for an input harmonic vibration of 0.03 g at a frequency of 61.7 Hz, corresponding to a 29.08 mW/cm 3 g 2 normalized power density performance, significantly higher than devices described in the literature for similar applications. Besides, a harvester prototype based on the proposed configuration has been fabricated to validate the modeling strategy used and to certify the reliability of the proposed design regarding power generation capabilities. Several experimental tests have been conducted under harmonic excitation with frequencies ranging between 10 Hz and 100 Hz and a vibration amplitude of 0.03 g. The experimentally measured induced voltage and electrical output power have been found in good agreement with their corresponding simulated values, with a difference of about 2.1% and 5%, respectivelyPostprint (published version

A mechanically-guided approach to three-dimensional functional mesostructures towards unconventional applications

Controlled formation of three-dimensional functional mesostructures (3DFMs) has broad engineering implications in biomedical devices, microelectromechanical systems (MEMS), optics, and energy storage. Most existing 3D techniques, however, not only lack compatibility with essential electronic materials (silicon, metals, ceramics) that exist in solid-state or crystalline forms, but also produce in a slow and inefficient manner. This is in stark contrast to the planar technologies widely adopted by the modern semiconductor industry. I propose to solve these challenges by a novel 3D assembly strategy based on the planar technologies, which involves precisely controlled 2D-to-3D transformations via the substrate-induced mechanical buckling. This lithography-based, mechanically-guided 3D approach is compatible with virtually any engineering thin films including semiconductors, metals, and polymers, applies to a wide range of length scales and geometries and produces in a high throughput. In this dissertation, I present strategies that combine fabrications and mechanics to achieve a set of complex 3D geometries. I also study the potentials of the 3DFMs in micro-robotics. I further demonstrate the unique applications in energy harvesting, bio-integrated systems, and nanoscale sensing. The results may enlighten the development of advanced, multi-functional 3D electronic micro-systems inaccessible to other 3D techniques

Advance in Energy Harvesters/Nanogenerators and Self-Powered Sensors

This reprint is a collection of the Special Issue "Advance in Energy Harvesters/Nanogenerators and Self-Powered Sensors" published in Nanomaterials, which includes one editorial, six novel research articles and four review articles, showcasing the very recent advances in energy-harvesting and self-powered sensing technologies. With its broad coverage of innovations in transducing/sensing mechanisms, material and structural designs, system integration and applications, as well as the timely reviews of the progress in energy harvesting and self-powered sensing technologies, this reprint could give readers an excellent overview of the challenges, opportunities, advancements and development trends of this rapidly evolving field

Low power wireless sensor applications.

Yuen Chi Lap.Thesis (M.Phil.)--Chinese University of Hong Kong, 2004.Includes bibliographical references (leaves 88-94).Abstracts in English and Chinese.Chapter 1 --- Introduction --- p.1Chapter 1.1 --- Motivation --- p.1Chapter 1.2 --- Aims --- p.2Chapter 1.3 --- Contributions --- p.3Chapter 1.4 --- Thesis Organization --- p.4Chapter 2 --- Background and Literature Review --- p.5Chapter 2.1 --- Introduction --- p.5Chapter 2.2 --- Vibration-to-Electrical Transducer --- p.6Chapter 2.2.1 --- Electromagnetic (Inductive) Power Conversion --- p.6Chapter 2.2.2 --- Electrostatic(Capacitive) Power Conversion --- p.8Chapter 2.2.3 --- Piezoelectric Power Conversion --- p.9Chapter 2.3 --- Wireless Sensor Platform Examples --- p.11Chapter 2.3.1 --- MICA[13] from UC Berkeley[49] --- p.11Chapter 2.3.2 --- WINS[48] from UCLA[51] --- p.13Chapter 2.3.3 --- Wong's Infrared System[5] --- p.13Chapter 2.4 --- Summary --- p.14Chapter 3 --- Micro Power Generator --- p.16Chapter 3.1 --- Introduction --- p.16Chapter 3.2 --- MEMS Resonator --- p.18Chapter 3.2.1 --- Laser-machinery --- p.18Chapter 3.2.2 --- Electroplating Fabrication --- p.18Chapter 3.3 --- Voltage Multiplier --- p.19Chapter 3.4 --- "Modeling, Simulations and Measurements" --- p.21Chapter 3.5 --- Summary --- p.30Chapter 4 --- Low Power Wireless Sensor Platform --- p.37Chapter 4.1 --- Introduction --- p.37Chapter 4.2 --- Generic Platform --- p.37Chapter 4.2.1 --- Startup Module and Power Management --- p.38Chapter 4.2.2 --- Control Unit --- p.43Chapter 4.2.3 --- Input Units (Sensor Peripherals) --- p.46Chapter 4.2.4 --- Output Units (Wireless Transmitters) --- p.48Chapter 4.3 --- Summary --- p.57Chapter 5 --- Application I - Wireless RF Thermometer --- p.59Chapter 5.1 --- Overview --- p.59Chapter 5.2 --- Implementation --- p.60Chapter 5.2.1 --- Prototype 1 --- p.60Chapter 5.2.2 --- Prototype 2 --- p.60Chapter 5.2.3 --- Prototype 3 --- p.62Chapter 5.2.4 --- Prototype 4 --- p.63Chapter 5.3 --- Results --- p.65Chapter 5.4 --- Summary --- p.67Chapter 6 --- Application II - 2D Input Ring --- p.70Chapter 6.1 --- Overview --- p.70Chapter 6.2 --- Architecture --- p.70Chapter 6.3 --- Software Implementation --- p.72Chapter 6.3.1 --- Methodology --- p.72Chapter 6.3.2 --- Error Control Code --- p.73Chapter 6.3.3 --- Peripheral Control Protocol --- p.75Chapter 6.4 --- Results --- p.77Chapter 6.5 --- Summary --- p.83Chapter 7 --- Conclusion --- p.84Chapter 7.1 --- Micro power generator --- p.84Chapter 7.2 --- Low power wireless sensor applications --- p.85Chapter 7.2.1 --- Wireless thermometer --- p.85Chapter 7.2.2 --- 2D input ring --- p.86Chapter 7.3 --- Further development --- p.86Bibliography --- p.88Chapter A --- Schematics --- p.9

Low power wireless sensor applications.

Yuen Chi Lap.Thesis (M.Phil.)--Chinese University of Hong Kong, 2004.Includes bibliographical references (leaves 88-94).Abstracts in English and Chinese.Chapter 1 --- Introduction --- p.1Chapter 1.1 --- Motivation --- p.1Chapter 1.2 --- Aims --- p.2Chapter 1.3 --- Contributions --- p.3Chapter 1.4 --- Thesis Organization --- p.4Chapter 2 --- Background and Literature Review --- p.5Chapter 2.1 --- Introduction --- p.5Chapter 2.2 --- Vibration-to-Electrical Transducer --- p.6Chapter 2.2.1 --- Electromagnetic (Inductive) Power Conversion --- p.6Chapter 2.2.2 --- Electrostatic(Capacitive) Power Conversion --- p.8Chapter 2.2.3 --- Piezoelectric Power Conversion --- p.9Chapter 2.3 --- Wireless Sensor Platform Examples --- p.11Chapter 2.3.1 --- MICA[13] from UC Berkeley[49] --- p.11Chapter 2.3.2 --- WINS[48] from UCLA[51] --- p.13Chapter 2.3.3 --- Wong's Infrared System[5] --- p.13Chapter 2.4 --- Summary --- p.14Chapter 3 --- Micro Power Generator --- p.16Chapter 3.1 --- Introduction --- p.16Chapter 3.2 --- MEMS Resonator --- p.18Chapter 3.2.1 --- Laser-machinery --- p.18Chapter 3.2.2 --- Electroplating Fabrication --- p.18Chapter 3.3 --- Voltage Multiplier --- p.19Chapter 3.4 --- "Modeling, Simulations and Measurements" --- p.21Chapter 3.5 --- Summary --- p.30Chapter 4 --- Low Power Wireless Sensor Platform --- p.37Chapter 4.1 --- Introduction --- p.37Chapter 4.2 --- Generic Platform --- p.37Chapter 4.2.1 --- Startup Module and Power Management --- p.38Chapter 4.2.2 --- Control Unit --- p.43Chapter 4.2.3 --- Input Units (Sensor Peripherals) --- p.46Chapter 4.2.4 --- Output Units (Wireless Transmitters) --- p.48Chapter 4.3 --- Summary --- p.57Chapter 5 --- Application I - Wireless RF Thermometer --- p.59Chapter 5.1 --- Overview --- p.59Chapter 5.2 --- Implementation --- p.60Chapter 5.2.1 --- Prototype 1 --- p.60Chapter 5.2.2 --- Prototype 2 --- p.60Chapter 5.2.3 --- Prototype 3 --- p.62Chapter 5.2.4 --- Prototype 4 --- p.63Chapter 5.3 --- Results --- p.65Chapter 5.4 --- Summary --- p.67Chapter 6 --- Application II - 2D Input Ring --- p.70Chapter 6.1 --- Overview --- p.70Chapter 6.2 --- Architecture --- p.70Chapter 6.3 --- Software Implementation --- p.72Chapter 6.3.1 --- Methodology --- p.72Chapter 6.3.2 --- Error Control Code --- p.73Chapter 6.3.3 --- Peripheral Control Protocol --- p.75Chapter 6.4 --- Results --- p.77Chapter 6.5 --- Summary --- p.83Chapter 7 --- Conclusion --- p.84Chapter 7.1 --- Micro power generator --- p.84Chapter 7.2 --- Low power wireless sensor applications --- p.85Chapter 7.2.1 --- Wireless thermometer --- p.85Chapter 7.2.2 --- 2D input ring --- p.86Chapter 7.3 --- Further development --- p.86Bibliography --- p.88Chapter A --- Schematics --- p.9

Mechanical Properties of Low Dimensional Materials

Recent advances in low dimensional materials (LDMs) have paved the way for unprecedented technological advancements. The drive to reduce the dimensions of electronics has compelled researchers to devise newer techniques to not only synthesize novel materials, but also tailor their properties. Although micro and nanomaterials have shown phenomenal electronic properties, their mechanical robustness and a thorough understanding of their structure-property relationship are critical for their use in practical applications. However, the challenges in probing these mechanical properties dramatically increase as their dimensions shrink, rendering the commonly used techniques inadequate. This Dissertation focuses on developing techniques for accurate determination of elastic modulus of LDMs and their mechanical responses under tensile and shear stresses. Fibers with micron-sized diameters continuously undergo tensile and shear deformations through many phases of their processing and applications. Significant attention has been given to their tensile response and their structure-tensile properties relations are well understood, but the same cannot be said about their shear responses or the structure-shear properties. This is partly due to the lack of appropriate instruments that are capable of performing direct shear measurements. In an attempt to fill this void, this Dissertation describes the design of an inexpensive tabletop instrument, referred to as the twister, which can measure the shear modulus (G) and other longitudinal shear properties of micron-sized individual fibers. An automated system applies a pre-determined twist to the fiber sample and measures the resulting torque using a sensitive optical detector. The accuracy of the instrument was verified by measuring G for high purity copper and tungsten fibers. Two industrially important fibers, IM7 carbon fiber and Kevlar® 119, were found to have G = 17 and 2.4 GPa, respectively. In addition to measuring the shear properties directly on a single strand of fiber, the technique was automated to allow hysteresis, creep and fatigue studies. Zinc oxide (ZnO) semiconducting nanostructures are well known for their piezoelectric properties and are being integrated into several nanoelectro-mechanical (NEMS) devices. In spite of numerous studies on the mechanical response of ZnO nanostructures, there is not a consensus in its measured bending modulus (E). In this Dissertation, by employing an all-electrical Harmonic Detection of Resonance (HDR) technique on ZnO nanowhisker (NW) resonators, the underlying origin for electrically-induced mechanical oscillations in a ZnO NW was elucidated. Based on visual detection and electrical measurement of mechanical resonances under a scanning electron microscope (SEM), it was shown that the use of an electron beam as a resonance detection tool alters the intrinsic electrical character of the ZnO NW, and makes it difficult to identify the source of the charge necessary for the electrostatic actuation. A systematic study of the amplitude of electrically actuated as-grown and gold-coated ZnO NWs in the presence (absence) of an electron beam using an SEM (dark-field optical microscope) suggests that the oscillations seen in our ZnO NWs are due to intrinsic static charges. In experiments involving mechanical resonances of micro and nanostructured resonators, HDR is a tool for detecting transverse resonances and E of the cantilever material. To add to this HDR capability, a novel method of measuring the G using HDR is presented. We used a helically coiled carbon nanowire (HCNW) in singly-clamped cantilever configuration, and analyzed the complex (transverse and longitudinal) resonance behavior of the nonlinear geometry. Accordingly, a synergistic protocol was developed which (i) integrated analytical, numerical (i.e., finite element using COMSOL ®) and experimental (HDR) methods to obtain an empirically validated closed form expression for the G and resonance frequency of a singly-clamped HCNW, and (ii) provided an alternative for solving 12th order differential equations. A visual detection of resonances (using in situ SEM) combined with HDR revealed intriguing non-planar resonance modes at much lower driving forces relative to those needed for linear carbon nanotube cantilevers. Interestingly, despite the presence of mechanical and geometrical nonlinearities in the HCNW resonance behavior, the ratio of the first two transverse modes f2/f1 was found to be similar to the ratio predicted by the Euler-Bernoulli theorem for linear cantilevers

Functional modelling and prototyping of electronic integrated kinetic energy harvesters

The aim of developing infinite-life autonomous wireless electronics, powered by the energy of the surrounding environment, drives the research efforts in the field of Energy Harvesting. Electromagnetic and piezoelectric techniques are deemed to be the most attractive technologies for vibrational devices. In the thesis, both these technologies are investigated taking into account the entire energy conversion chain. In the context of the collaboration with the STMicroelectronics, the project of a self-powered Bluetooth step counter embedded in a training shoe has been carried out. A cylindrical device 27 × 16mm including the transducer, the interface circuit, the step-counter electronics and the protective shell, has been developed. Environmental energy extraction occurs exploiting the vibration of a permanent magnet in response to the impact of the shoe on the ground. A self-powered electrical interface performs maximum power transfer through optimal resistive load emulation and load decoupling. The device provides 360 μJ to the load, the 90% of the maximum recoverable energy. The energy requirement is four time less than the provided and the effectiveness of the proposed device is demonstrated also considering the foot-steps variability and the performance spread due to prototypes manufacturing. In the context of the collaboration with the G2Elab of Grenoble and STMicroelectronics, the project of a piezoelectric energy arvester has been carried out. With the aim of exploiting environmental vibrations, an uni-morph piezoelectric cantilever beam 60×25×0.5mm with a proof mass at the free-end has been designed. Numerical results show that electrical interfaces based on SECE and sSSHI techniques allows increasing performance up to the 125% and the 115% of that in case of STD interface. Due to the better performance in terms of harvested power and in terms of electric load decoupling, a self-powered SECE interface has been prototyped. In response to 2 m/s2 56,2 Hz sinusoidal input, experimental power recovery of 0.56mW is achieved demonstrating that the device is compliant with standard low-power electronics requirements

Energy Academic Group Compilation of Abstracts 2012-2016

This report highlights the breadth of energy-related student research at NPS and reinforces the importance of energy as an integral aspect of today's Naval enterprise. The abstracts provided are from theses and a capstone project report completed by December 2012-March 2016 graduates.http://archive.org/details/energyacademicgr109454991

Field Disruption Energy Harvester Design and Modeling: A Novel Approach in Electromagnetic Vibration Energy Harvesting

The demand for sustainable and non-traditional sources of energy increases every day to power up different electronic equipment whether it's portable low-power devices, non-accessible sensors, wearable electronics, implantable medical devices, and even for big scale applications that can contribute to the energy demand on a public level. Energy harvesting from vibrations offers an ideal source of energy, since it's renewable and prevailing, where kinetic energy that can be harvested is abundant in nature. \newline In this proposal, a novel electromagnetic transduction mechanism is introduced that can be used in harvesting low-frequency vibrations below 10 Hz, which makes it suitable to harvest motion from human locomotion, moving vehicles, and structures like buildings, bridges and streets. The transduction mechanism developed induces a current in a coil by disrupting the electromagnetic field in the vicinity of a stationary coil wound around a hollow track (tube) made of non-conducting or conducting (copper) material, where a ball made of ferromagnetic material is moving freely along the track cutting the field lines and induces current in the coil. Prototypes embodying the harvesting mechanism were fabricated and tested to identify the different system parameters, frequency-responses and characterize the harvester in order to derive a representative mathematical model. The performance of the energy harvester was measured and characterized in terms of output power, power density and tunability. Where the prototypes fabricated demonstrated a capability to harvest energy at low-frequencies in the range of 6.54-12.72 Hz , with a 3 dB harvesting bandwidth ranging between 1.32 Hz to 5.8 Hz, and generated output power up to 154 micro-Watt. The proposed transduction mechanism demonstrated a strong flexibility that allows tuning the center frequency magnetically, without the need to modify the mechanical design, in order to take advantage of this feature, an intelligent fuzzy tuner design is proposed, supported with simulation results that show the potential of adaptive control of center frequency to increase the generated output power. \newline This abstract proposes a future plan for the development of the intelligent fuzzy tuner hardware and it's validation to increase the generated output power and power density at low frequencies while reducing the need for any external interference in the harvester's operation, leading the way for a new generation of adaptive vibrations-based energy harvesters

Energy Harvesting Technologies for Achieving Self-Powered Wireless Sensor Networks in Machine Condition Monitoring:A Review

Condition monitoring can reduce machine breakdown losses, increase productivity and operation safety, and therefore deliver significant benefits to many industries. The emergence of wireless sensor networks (WSNs) with smart processing ability play an ever-growing role in online condition monitoring of machines. WSNs are cost-effective networking systems for machine condition monitoring. It avoids cable usage and eases system deployment in industry, which leads to significant savings. Powering the nodes is one of the major challenges for a true WSN system, especially when positioned at inaccessible or dangerous locations and in harsh environments. Promising energy harvesting technologies have attracted the attention of engineers because they convert microwatt or milliwatt level power from the environment to implement maintenance-free machine condition monitoring systems with WSNs. The motivation of this review is to investigate the energy sources, stimulate the application of energy harvesting based WSNs, and evaluate the improvement of energy harvesting systems for mechanical condition monitoring. This paper overviews the principles of a number of energy harvesting technologies applicable to industrial machines by investigating the power consumption of WSNs and the potential energy sources in mechanical systems. Many models or prototypes with different features are reviewed, especially in the mechanical field. Energy harvesting technologies are evaluated for further development according to the comparison of their advantages and disadvantages. Finally, a discussion of the challenges and potential future research of energy harvesting systems powering WSNs for machine condition monitoring is made