Piezoelectric Energy Harvesting: Enhancing Power Output by Device Optimisation and Circuit Techniques

Energy harvesting; that is, harvesting small amounts of energy from environmental sources such as solar, air flow or vibrations using small-scale (≈1cm 3 ) devices, offers the prospect of powering portable electronic devices such as GPS receivers and mobile phones, and sensing devices used in remote applications: wireless sensor nodes, without the use of batteries. Numerous studies have shown that power densities of energy harvesting devices can be hundreds of µW; however the literature also reveals that power requirements of many electronic devices are in the mW range. Therefore, a key challenge for the successful deployment of energy harvesting technology remains, in many cases, the provision of adequate power. This thesis aims to address this challenge by investigating two methods of enhancing the power output of a piezoelectric-based vibration energy harvesting device. Cont/d

Reliability improvement of electronic circuits based on physical failure mechanisms in components

Traditionally the position of reliability analysis in the design and production process of electronic circuits is a position of reliability verification. A completed design is checked on reliability aspects and either rejected or accepted for production. This paper describes a method to model physical failure mechanisms within components in such a way that they can be used for reliability optimization, not after, but during the early phase of the design process. Furthermore a prototype of a CAD software tool is described, which can highlight components likely to fail and automatically adjust circuit parameters to improve product reliability

Gallium nitride high electron mobility transistors in chip scale packaging: evaluation of performance in radio frequency power amplifiers and thermomechanical reliability characterization

2017 Summer.Includes bibliographical references.Wide bandgap semiconductors such as Gallium Nitride (GaN) have many advantages over their Si counterparts, such as a higher energy bandgap, critical electric field, and saturated electron drift velocity. These parameters translate into devices which operate at higher frequency, voltage, and efficiency than comparable Si devices, and have been utilized in varying degrees for power amplification purposes at >1 MHz for years. Previously, these devices required costly substrates such as sapphire (Al2O3), limiting applications to little more than aerospace and military. Furthermore, the typical breakdown voltage ratings of these parts have historically been below ~200 V, with many targeted as replacements for 50 V Si LDMOS as used in cellular infrastructure and industrial, scientific, and medical (ISM) applications between 1 MHz and 1 GHz. Fortunately within the past five years, devices have become commercially available with attractive key specifications: GaN on Si subtrates, with breakdown voltages of over 600 V, realized in cost effective chip scale packages, and with inherently low parasitic capacitances and inductances. In this work, two types of inexpensive commercially available AlGaN/GaN high electron mobility transistors (HEMTs) in chip scale packages are evaluated in a set of three interconnected experiments. The first explores the feasibility of creating a radio frequency power amplifier for use in the ISM bands of 2 MHz and 13.56 MHz, at power levels of up to 1 kW, using a Class E topology. Experiments confirm that a DC to RF efficiency of 94% is easily achievable using these devices. The second group of experiments considers both the steady state and transient thermal characterization of the HEMTs when installed in a typical industrial application. It is shown that both types of devices have acceptable steady state thermal resistance performance; approximately 5.27 °C/W and 0.93 °C/W are achievable for the source pad (bottom) cooled and top thermal pad cooled device types, respectively. Transient thermal behavior was found to exceed industry recommended maximum dT/dt by over 80x for the bottom cooled devices; a factor of 20x was noted with the top cooled devices. Extrapolations using the lumped capacitance method for transient conduction support even higher initial channel dT/dt rates. Although this rate of change decays to recommended levels within one second, it was hypothesized that the accumulated mechanical strain on the HEMTs would cause early life failures if left uncontrolled. The third set of experiments uses the thermal data to design a set of experiments with the goal of quantifying the cycles to failure under power cycling. It is confirmed that to achieve a high number of thermal cycles to failure as required in high reliability industrial systems, the devices under test require significant thermal parameter derating to levels on the order of 50%

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

Nanoscale III-V Semiconductor Photodetectors for High-Speed Optical Communications

Nanophotonics involves the study of the behavior of light on nanometer scale. Modern nanoscale semiconductor photodetectors are important building blocks for high-speed optical communications. In this chapter, we review the state-of-the-art 2.5G, 10G, and 25G avalanche photodiodes (APDs) that are available in commercial applications. We discuss the key device parameters, including avalanche breakdown voltage, dark current, temperature dependence, bandwidth, and sensitivity. We also present reliability analysis on wear-out degradation and optical/electrical overload stress. We discuss the reliability challenges of nanoscale photodetectors associated with device miniaturization for the future. The reliability aspects in terms of high electric field, Joule heating, and geometry inhomogeneity are highlighted

Power Semiconductors for An Energy-Wise Society

This IEC White Paper establishes the critical role that power semiconductors play in transitioning to an energy wise society. It takes an in-depth look at expected trends and opportunities, as well as the challenges surrounding the power semiconductors industry. Among the significant challenges mentioned is the need for change in industry practices when transitioning from linear to circular economies and the shortage of skilled personnel required for power semiconductor development. The white paper also stresses the need for strategic actions at the policy-making level to address these concerns and calls for stronger government commitment, policies and funding to advance power semiconductor technologies and integration. It further highlights the pivotal role of standards in removing technical risks, increasing product quality and enabling faster market acceptance. Besides noting benefits of existing standards in accelerating market growth, the paper also identifies the current standardization gaps. The white paper emphasizes the importance of ensuring a robust supply chain for power semiconductors to prevent supply-chain disruptions like those seen during the COVID-19 pandemic, which can have widespread economic impacts.The white paper highlights the importance of inspiring young professionals to take an interest in power semiconductors and power electronics, highlighting the potential to make a positive impact on the world through these technologies.The white paper concludes with recommendations for policymakers, regulators, industry and other IEC stakeholders for collaborative structures and accelerating the development and adoption of standards

Running Shoe Pedometer

Running shoe pedometer aims to solve the issue of worn out running shoes. It can be difficult to know just how many miles you have run in your shoes and when a new pair is needed. Running in old shoes and worn out shoes is heavily linked to injury. My proposed project is a device that is powered by the compressive forces on the shoes soles that counts the number of steps the wearer takes using a microcontroller. Then, when the shoe reaches milestone that indicate it has been used 75% 90% and 100% of its expected life, it will output the information to the user. In order to output the wear life of the shoes to the user, a series of color changing chemical reactions will be used. These reactions will most likely be acid/base with some type of indicator or an electrochromic material. These color changes will allow the user to see that their shoes are worn out. The device should be extremely low cost so that it can be built into a running shoe and disposed of when the shoe is worn out

Piezoelectric energy harvesting : enhancing power output by device optimisation and circuit techniques

Energy harvesting; that is, harvesting small amounts of energy from environmental sources such as solar, air flow or vibrations using small-scale (≈1cm 3 ) devices, offers the prospect of powering portable electronic devices such as GPS receivers and mobile phones, and sensing devices used in remote applications: wireless sensor nodes, without the use of batteries. Numerous studies have shown that power densities of energy harvesting devices can be hundreds of µW; however the literature also reveals that power requirements of many electronic devices are in the mW range. Therefore, a key challenge for the successful deployment of energy harvesting technology remains, in many cases, the provision of adequate power. This thesis aims to address this challenge by investigating two methods of enhancing the power output of a piezoelectric-based vibration energy harvesting device. Cont/d.EThOS - Electronic Theses Online ServiceGBUnited Kingdo