89 results found
Kiziroglou ME, Yeatman EM, 2021, Micromechanics for energy generation, Journal of Micromechanics and Microengineering, Vol: 31, Pages: 1-18, ISSN: 0960-1317
The emergence and evolution of energy micro-generators during the last two decades has delivered a wealth of energy harvesting powering solutions, with the capability of exploiting a wide range of motion types, from impulse and low frequency irregular human motion, to broadband vibrations and ultrasonic waves. It has also created a wide background of engineering energy microsytems, including fabrication methods, system concepts and optimal functionality. This overview presents a simple description of the main transduction mechanisms employed, namely the piezoelectric, electrostatic, electromagnetic and triboelectric harvesting concepts. A separate discussion of the mechanical structures used as motion translators is presented, including the employment of a proof mass, cantilever beams, the role of resonance, unimorph structures and linear/rotational motion translators. At the mechanical-to-electrical interface, the concepts of impedance matching, pre-biasing and synchronised switching are summarised. The separate treatment of these three components of energy microgenerators allows the selection and combination of different operating concepts, their co-design towards overall system level optimisation, but also towards the generalisation of specific approaches, and the emergence of new functional concepts. Industrial adoption of energy micro-generators as autonomous power sources requires functionality beyond the narrow environmental conditions typically required by the current state-of-art. In this direction, the evolution of broadband electromechanical oscillators and the combination of environmental harvesting with power transfer operating schemes could unlock a widespread use of micro-generation in microsystems such as micro-sensors and micro-actuators.
Becker T, Borjesson V, Cetinkaya O, et al., 2021, Energy harvesting for a green internet of things, PSMA
The ubiquitous nature of energy autonomous microsystems, which are easy to install and simple toconnect to a network, make them attractive in the rapidly growing Internet of Things (IoT) ecosystem.The growing energy consumption of the IoT infrastructure is becoming more and more visible. Energyharvesting describes the conversion of ambient into electrical energy, enabling green power suppliesof IoT key components, such as autonomous sensor nodes.Energy harvesting methods and devices have reached a credible state-of-art, but only a few devices arecommercially available and off-the-shelf harvester solutions often require extensive adaption to theenvisaged application. A synopsis of typical energy sources, state-of-the-art materials, and transducertechnologies for efficient energy conversion, as well as energy storage devices and power managementsolutions, depicts a wide range of successful research results. Developing power supplies for actualusage reveals their strong dependence on application-specific installation requirements, powerdemands, and environmental conditions.The industrial challenges for a massive spread of autonomous sensor systems are manifold anddiverse. Reliability issues, obsolescence management, and supply chains need to be analyzed forcommercial use in critical applications. The current gap between use-case scenarios and innovativeproduct development is analyzed from the perspective of the user. The white paper then identifies thekey advantages of energy autonomy in environmental, reliability, sustainability, and financial terms.Energy harvesting could lead to a lower CO2 footprint of future IoT devices by adoptingenvironmentally friendly materials and reducing cabling and battery usage. Further research anddevelopment are needed to achieve technology readiness levels acceptable for the industry. This whitepaper derives a future research and innovation strategy for industry-ready green microscale IoTdevices, providing useful information to the sta
Yang S, Kiziroglou M, Yeatman E, et al., 2021, Passive acoustic transducer as a fluid flow sensor, IEEE Sensors Conference, Publisher: IEEE
Autonomy and minimal disruption are key desirable features for sensors to be deployed in medical, industrial, vehicle and infrastructure monitoring systems. Using a passive structure to transduce the quantity of interest into an acoustic or electromagnetic wave could offer an attractive solution for remote sensing, lifting the requirements of installing active materials, electronics, and power sources in remote, inaccessible, sensitive, or harsh environment locations. Here, we report a simple cavity and ball structure that transduces fluid flow through a pipe into an acoustic signal. A microphone on the outside wall of the pipe records the intensity and arrival rate of the sound pulses generated by collisions between the ball and the cavity walls. Using this approach external measurement of flow is demonstrated with adequate repeatability before any acoustic signal processing. This result is expected to open the way to the implementation of passive, remotely readable sensors for fluid flow and other fluid properties of interest.
Kiziroglou ME, Wright SW, Yeatman EM, 2021, Power supply based on inductive harvesting from structural currents, IEEE Internet of Things Journal, ISSN: 2327-4662
Monitoring infrastructure offers functional optimisation, lower maintenance cost, security, stability and data analysis benefits. Sensor nodes require some level of energy autonomy for reliable and cost-effective operation, and energy harvesting methods have been developed in the last two decades for this purpose. Here, a power supply that collects, stores and delivers regulated power from the stray magnetic field of currentcarrying structures is presented. In cm-scale structures the skin effect concentrates current at edges at frequencies even below 1 kHz. A coil-core inductive transducer is designed. A fluxfunnelling soft magnetic core shape is used, multiplying power density by the square of funnelling ratio. A power management circuit combining reactance cancellation, voltage doubling, rectification, super-capacitor storage and switched inductor voltage boosting and regulation is introduced. The power supply is characterised in house and on a full-size industrial setup, demonstrating a power reception density of 0.36 mW/cm3, 0.54 mW/cm3 and 0.73 mW/cm3 from a 25 A RMS structural current at 360 Hz, 500 Hz and 800 Hz respectively, corresponding to the frequency range of aircraft currents. The regulated output is tested under various loads and cold starting is demonstrated. The introduced method may enable power autonomy to wireless sensors deployed in current-carrying infrastructure.
Sensor installation on water infrastructure is challenging due to requirements for service interruption, specialised personnel, regulations and reliability as well as the resultant high costs. Here, a minimally invasive installation method is introduced based on hot-tapping and immersion of a sensor probe. A modular architecture is developed that enables the use of interchangeable multi-sensor probes, non-specialist installation and servicing, low-power operation and configurable sensing and connectivity. A prototype implementation with a temperature, pressure, conductivity and flow multi-sensor probe is presented and tested on an evaluation rig. This paper demonstrates simple installation, reliable and accurate sensing capability as well as remote data acquisition. The demonstrated minimally invasive multi-sensor probes provide an opportunity for the deployment of water quality sensors that typically require immersion such as pH and spectroscopic composition analysis. This design allows dynamic deployment on existing water infrastructure with expandable sensing capability and minimal interruption, which can be key to addressing important sensing parameters such as optimal sensor network density and topology.
Pandiyan A, Boyle D, Kiziroglou M, et al., 2020, Optimal dynamic recharge scheduling for two stage wireless power transfer, IEEE Transactions on Industrial Informatics, Vol: 17, Pages: 5719-5729, ISSN: 1551-3203
Many Industrial Internet of Things applications require autonomous operation and incorporate devices in inaccessible locations. Recent advances in wireless power transfer (WPT) and autonomous vehicle technologies, in combination, have the potential to solve a number of residual problems concerning the maintenance of, and data collection from embedded devices. Equipping inexpensive unmanned aerial vehicles (UAV) and embedded devices with subsystems to facilitate WPT allows a UAV to become a viable mobile power delivery vehicle (PDV) and data collection agent. A key challenge is therefore to ensure that a PDV can optimally schedule power delivery across the network, such that it is as reliable and resource efficient as possible. To achieve this and out-perform naive on-demand recharging strategies, we propose a two-stage wireless power network (WPN) approach in which a large network of devices may be grouped into small clusters, where packets of energy inductively delivered to each cluster by the PDV are acoustically distributed to devices within the cluster. We describe a novel dynamic recharge scheduling algorithm that combines genetic weighted clustering with nearest neighbour search to jointly minimize PDV travel distance and WPT losses. The efficacy and performance of the algorithm are evaluated in simulation using experimentally derived traces, and the algorithm is shown to achieve 90% throughput for large, dense networks.
Kiziroglou ME, Wright SW, Yeatman EM, 2020, Coil and core design for inductive energy receivers, Sensors and Actuators A: Physical, Vol: 313, Pages: 1-9, ISSN: 0924-4247
The design of coil/core transducers is important for maximizing the power density of inductive energy receivers for both inductive energy harvesting and power transfer. In this work, we present a study of core and coil performance, based on a simulated flux distribution corresponding to aircraft applications. The use of funnel-shaped soft magnetic cores boosts magnetic flux density by flux concentration and allows the use of a smaller diameter coil. This reduces the transducer mass as well as the coil resistance (RCOIL), thereby increasing the available power density. Analysis and simulation shows a fifty-fold power density increase from moderate funneling and another two-fold increase by coil size optimization. Results are compared with experimental measurements which demonstrate a 31 μW/g power density from alternating environmental magnetic fields in the 10 μT/360 Hz range.
Lombardi G, Lallart M, Kiziroglou M, et al., 2020, A piezoelectric self-powered active interface for AC/DC power conversion improvement of electromagnetic energy harvesting, Smart Materials and Structures, Vol: 29, ISSN: 0964-1726
In the framework of hybrid energy harvesting for scavenging ambient motion, this paper proposes a cooperative piezoelectricelectromagnetic energy harvesting system to harvest rotational energy. In particular, while the actual process of harvesting energy is accomplished by the electromagnetic device, the piezoelectric element is used for improving the AC/DC conversion efficiency of the former. To do so, a half wave voltage doubler using MOSFETs driven by the piezoelement is employed. The low voltage output (order of magnitude of mV) of the electromagnetic system and the low conversion abilities of the piezoelectric transducer in the proposed mechanical structure justifies the motivation behind this work. Simulations followed by experimental validations are exposed and discussed, highlighting the improvement of energy conversion efficiency of an electromagnetic transducer, giving a power gain of 27 with respect to the DC power obtained with standard silicon diodes.
Kiziroglou ME, Wright SW, Yeatman EM, 2020, Shaped coil-core design for inductive energy collectors, 19th International Conference on Micro and Nanotechnology for Power Generation and Energy Conversion Applications (Power MEMS), Publisher: IEEE, Pages: 1-4
Coil design is important for maximizing power density in inductive energy harvesting as well as in inductive power transfer. In this work, we present a study of coil performance, based on simulated flux distributions corresponding to a real aircraft application case. The use of funnel-shaped soft magnetic cores boosts magnetic flux density by flux concentration and allows the use of a smaller diameter coil. This reduces the transducer mass as well as the coil resistance (R COIL ), thereby increasing the power density. Analysis and simulation shows a fifty-fold power density increase from moderate funneling and another two-fold increase by coil size optimization. Results are compared with experimental measurements presented in  which demonstrate a 36μW/g(106μW/cm 3 ) power density from alternating environmental magnetic fields in the 10μT/300 Hz range.
Many motion-active materials have recently emerged, with new methods of integration into actuator components and systems-on-chip. Along with established microprocessors, interconnectivity capabilities and emerging powering methods, they offer a unique opportunity for the development of interactive millimeter and micrometer scale systems with combined sensing and actuating capabilities. The amplification of nanoscale material motion to a functional range is a key requirement for motion interaction and practical applications, including medical micro-robotics, micro-vehicles and micro-motion energy harvesting. Motion amplification concepts include various types of leverage, flextensional mechanisms, unimorphs, micro-walking /micro-motor systems, and structural resonance. A review of the research state-of-art and product availability shows that the available mechanisms offer a motion gain in the range of 10. The limiting factor is the aspect ratio of the moving structure that is achievable in the microscale. Flexures offer high gains because they allow the application of input displacement in the close vicinity of an effective pivotal point. They also involve simple and monolithic fabrication methods allowing combination of multiple amplification stages. Currently, commercially available motion amplifiers can provide strokes as high as 2% of their size. The combination of high-force piezoelectric stacks or unimorph beams with compliant structure optimization methods is expected to make available a new class of high-performance motion translators for microsystems.
Lombardi G, Lallart M, Kiziroglou M, et al., 2020, AC/DC power conversion improvement of rotational electromagnetic energy harvesting using piezoelectric elements for active rectification, 19th International Conference on Micro and Nanotechnology for Power Generation and Energy Conversion Applications (Power MEMS), Publisher: IEEE
Pandiyan AYS, La Rosa R, Kiziroglou ME, et al., 2020, Understanding Far Field Ultrasonic Power Transmission for Automobile Sensor Networks in Free Space, 19th International Conference on Micro and Nanotechnology for Power Generation and Energy Conversion Applications (Power MEMS), Publisher: IEEE
Pandiyan AYS, Kiziroglou ME, Boyle DE, et al., 2020, Optimal Energy Management of Two Stage Energy Distribution Systems Using Clustering Algorithm, 19th International Conference on Micro and Nanotechnology for Power Generation and Energy Conversion Applications (Power MEMS), Publisher: IEEE
Modern non-invasive medical sensors can continuously provide vital information such as blood oxygenation, hemoglobin and glucose, based on substance-specific spectral or electrochemical properties. Cells and other geometrical formations are difficult to observe non-invasively due to the absence of a distinctive substantial signature. Optical scattering angle measurements could provide geometrical information but multiple scattering results in diffusion profiles, limiting their direct applicability. Mie scattering correlation to blood cell size has been demonstrated in the lab and various biomedical optical techniques are under intense investigation towards decoupling direct from indirect scattering, requiring specialized equipment. In this paper, a portable sensor is introduced for in-vitro and potentially in-vivo study of light scattering from blood. A microcontroller-based prototype has been designed and fabricated, with a 650 nm laser source, a 128 × 1 photodiode array and a custom dual-core real-time data acquisition algorithm. The prototype has been evaluated using latex sphere solutions calibrated to emulated red blood cells, white blood cells and platelets. Distinct scattering signatures are demonstrated for the three blood cell sizes. Reproducibility and repeatability tests analyzing data from multiple independent experiments demonstrate the reliability of the demonstration. This device platform provides a flexible and simple means for evaluating optical processing methods towards non-invasive continuous counting of blood cells.
Wright S, Kiziroglou M, Spasic S, et al., 2019, Inductive energy harvesting from current-carrying structures, IEEE Sensors Letters, Vol: 3, ISSN: 2475-1472
This article introduces an inductive method for harvesting energy from current-carrying structures. Numerical simulation of a structural beam shows that the skin effect can lead to significant current concentration at edges, providing a five-fold power benefit at such locations, even at frequencies below 1 kHz. The use of a rectangular ferrite core can provide a ×4 power density improvement. The adoption of funnel-like core shapes allows the reduction of core mass and coil frame size, leading to significant further power density enhancement. Magnetic field simulation and coil analysis demonstrate a power density increase of ×49 by ferrite funnels, in comparison to a coreless coil. Experimental results demonstrate rectified power over 1 mW delivered to a storage capacitor, from a 40 × 20 × 2 mm core-and-coil, in the vicinity of a spatially distributed 20 A current at 800 Hz. Rectification and impedance matching are studied experimentally using a voltage doubler circuit with input capacitor tuning to counteract the coil reactance. Experimental results from a spatially distributed 30 A current at 300 Hz and a 1:7 funnel core demonstrate power density of 36 μ W/g (103 μ W/cm 3 ), opening up the way to noninvasive inductive powering of systems in the vicinity of current-carrying structures.
Boyle DE, Wright SW, Kiziroglou ME, et al., 2019, Inductive Power Delivery with Acoustic Distribution to Wireless Sensors, IEEE MTT-S Wireless Power Transfer Conference (WPTC) / IEEE PELS Workshop on Emerging Technologies - Wireless Power (WoW) / Wireless Power Week Conference, Publisher: IEEE, Pages: 202-204
Kiziroglou M, Wright S, Shi M, et al., 2019, Milliwatt power supply by dynamic thermoelectric harvesting, PowerMEMS 2018, Publisher: Institute of Physics (IoP), Pages: 1-4, ISSN: 1742-6588
In this work we demonstrate a power supply that collects thermal energy from temperature fluctuations in time, to provide regulated power in the milliwatt range. It is based on the dynamic thermoelectric energy harvesting concept, in which a phase change material is used to store heat and create spatial heat flow from temperature transients. A simple, cost-effective and reproducible fabrication method is employed, based on 3D printing and off-the-shelf components. The harvester is integrated with a commercial power management module and supercapacitor storage. Output energy up to 2 J is demonstrated from temperature cycles corresponding to avionic applications. The demonstration includes harvesting while powering a 10 kΩ analogue voltmeter directly from the supercapacitor, including during cold-starting.
Karakostas K, Gkagkanis S, Katsaliaki K, et al., 2019, Blood cell size determination by scattering analysis, 5th PAnhellenic Conference on Electronics and Telecommunications (PACET), Publisher: IEEE, Pages: 157-161
Kiziroglou M, Cowell M, Kumaravel BT, et al., 2018, Speed vs efficiency and storage type in portable energy systems, PowerMEMS 2017, Publisher: Institute of Physics (IoP), ISSN: 1742-6588
Portable power management systems must optimise power interfacing, storage androuting, to meet application specific functionality requirements. Two key aspects are reliabilityand efficiency. For reliable operation, it is required that powering on/off the system must occurin a planned manner. For efficient operation, it is desired that the system is powered for anoptimal amount of time. maximizing its useful operational outcome per unit of energy consumed.This can be achieved by optimizing energy usage based on the anticipated energy income andpower demand of duty-cycled power consumers. Both battery and supercapacitor storage can beemployed to meet energy and power density demand, on both sides, and to enable fast transitionfrom cold-starting to active power management. A simplified model is used to calculate thereliability of a simple solar-powered microsystem. The modelling of dynamically configurableinterfacing and storage may enable a new generation of power management, providing reliablepower from irregular and small energy sources.
Allmen L, Bailleul G, Becker T, et al., 2017, Aircraft strain WSN powered by heat storage harvesting, IEEE Transactions on Industrial Electronics, Vol: 64, Pages: 7284-7292, ISSN: 0278-0046
The combination of ultra-low-power wireless communications and energy harvesting enables the realization of autonomous wireless sensor networks. Such networks can be usefully applied in commercial aircraft where wireless sensing solutions contribute to weight reduction and increased ease of installation and maintenance. This paper presents, for the first time, a complete energy-autonomous wireless strain monitoring system for aircraft. The system is based on a multimode wireless time-division multiple access (TDMA) medium access control (MAC) protocol that supports automatic configuration and a time-stamping accuracy better than 1 ms. The energy supply depends solely on an innovative thermoelectric energy harvester, which takes advantage of the changes in environmental temperature during takeoff and landing. The system was successfully integrated and passed the functional and flight-clearance tests that qualify it for use in a flight-test installation.
Kiziroglou M, Becker T, Wright SW, et al., 2017, Three-Dimensional Printed Insulation For Dynamic Thermoelectric Harvesters With Encapsulated Phase Change Materials, IEEE Sensors Letters, Vol: 1, ISSN: 2475-1472
Energy harvesting devices have demonstrated their ability to provide power autonomy to wireless sensor networks. However, the adoption of such powering solutions by the industry is challenging due to their reliance on very specific environmental conditions such as vibration at a specific frequency, direct sunlight, or a local temperature difference. Dynamic thermoelectric harvesting has been shown to expand the applicability of thermoelectric generators by creating a local spatial temperature gradient from a temporal temperature fluctuation. Here, a simple method for prototyping or short-run production of such devices is introduced. It is based on the design and 3-D printing of an insulating container, insertion of a phase change material in encapsulated form, and use of commercial thermoelectric generators. The simplicity of this dry assembly method is demonstrated. Two prototype devices with double-wall insulation structures are fabricated, using a stainless-steel and a plastic phase change material encapsulation and a commercial TEG. Performance tests under a temperature cycle between ±25 °C show energy output of 43.6 and 32.1 J from total device masses of 69 and 50 g, respectively. Tests under multiple temperature cycles demonstrate the reliability and performance repeatability of such devices. The proposed method addresses the complication of requiring a wet stage during the final assembly of dynamic thermoelectric harvesters. It allows design and customization to particular size, energy, and insulation geometry requirements. This is important because it makes dynamic harvesting prototyping widely available and easy to reproduce, test, and integrate into systems with various energy requirements and size restrictions.
Kiziroglou ME, Becker T, Yeatman EM, et al., 2017, Comparison of methods for static charge energy harvesting on aircraft, SPIE Microtechnologies, Publisher: Society of Photo-optical Instrumentation Engineers (SPIE), ISSN: 1996-756X
In this paper, the possibility of using the static charge that accumulates on aircraft during flight as a source to power monitoring sensors is examined. The assessed methods include using a pair of materials with different air-flow charging rates, contact discharging of the fuselage to neutral metallic bodies, charge motion induction by the fuselage field and inductive harvesting of fuselage-to-air corona discharges at static discharge wicks. The installation and potential advantages of each method are discussed. The feasibility of directly charging a storage capacitor from accumulated static charge is studied experimentally, demonstrating a voltage of 25V on a 25nF capacitor.
Iosifidis C, Katsaliaki K, Kollensperger P, et al., 2017, Design of an embedded sensor system for measuring laserscattering on blood cells, SPIE Microtechnologies, Publisher: Society of Photo-optical Instrumentation Engineers (SPIE), ISSN: 1996-756X
In this paper, a sensor system architecture for laboratory and in-vivo light scattering studies on blood cells is presented. It aims at correlating Mie scattering to compositional and physiological information of blood cells towards a non-invasive blood-cell counting sensor. An overview of previously reported experimental techniques on light scattering from blood cells is presented. State-of-the-art methods such as differential pulse measurements, vessel pressure optimization identified as promising for enhancing the scattering signal in such measurements. Indicative simulations of Mie scattering by blood cells are presented, illustrating the potential for distinguishing among cells and identifying size distribution. A prototype sensor system based on a 640-660 nm laser light source and a photo diode array is implemented and programmed to obtain mean amplitude and scattering angle measurements.
Gramling HM, Kiziroglou ME, Yeatman EM, 2017, Nanotechnology for Consumer Electronics, Nanoelectronics: Materials, Devices, Applications, Publisher: Wiley, Pages: 501-526, ISBN: 9783527800728
© 2017 Wiley-VCH Verlag GmbH & Co.KGaA. All rights reserved. Nanotechnology is already inherent in communication modules through the ubiquitous use of low cost, highly functional silicon integrated circuits. Motion processing units, portable biomedical sensors, and imaging sensors are discussed along with relevant nanotechnologies, both current and imminent. Nanotechnology-enhanced glucose sensors are expected in commercial glucose monitoring systems in the next few years. Nevertheless, advances in nanotechnology could soon play a significant role in the evolution of optical sensors for consumer electronics. Nanotechnology is expected to play a significant role in the technology evolution of organic light-emitting diode (OLED) devices. Nanotechnologies are of critical importance to the progress of liquid crystal displays (LCDs), electrophoretic, and electrochromic displays, all of whose operating principles fundamentally rely on nanoscaled structures. Nanotechnology is essential to the continuing advances in integrated electronics: increasing computational power, reducing device scale, and limiting energy consumption.
Kiziroglou M, Boyle D, Wright S, et al., 2017, Acoustic power delivery to pipeline monitoring wireless sensors, Ultrasonics, Vol: 77, Pages: 54-60, ISSN: 1874-9968
The use of energy harvesting for powering wireless sensors is made more challenging in most applications by the requirement for customization to each specific application environment because of specificities of the available energy form, such as precise location, direction and motion frequency, as well as the temporal variation and unpredictability of the energy source. Wireless power transfer from dedicated sources can overcome these difficulties, and in this work, the use of targeted ultrasonic power transfer as a possible method for remote powering of sensor nodes is investigated. A powering system for pipeline monitoring sensors is described and studied experimentally, with a pair of identical, non6inertial piezoelectric transducers used at the transmitter and receiver. Power transmission of 18 mW (Root6Mean6Square) through 1 m of a 118 mm diameter cast iron pipe, with 8 mm wall thickness is demonstrated. By analysis of the delay between transmission and reception, including reflections from the pipeline edges, a transmission speed of 1000 m/s is observed, corresponding to the phase velocity of the L(0,1) axial and F(1,1) radial modes of the pipe structure. A reduction of power delivery with water6filling is observed, yet over 4 mW of delivered power through a fully6filled pipe is demonstrated. The transmitted power and voltage levels exceed the requirements for efficient power management, including rectification at cold6starting conditions, and for the operation of low6power sensor nodes. The proposed powering technique may allow the implementation of energy autonomous wireless sensor systems for monitoring industrial and network pipeline infrastructure.
Pervasive sensing - the capability to deploy large numbers of sensors, to link them to communication networks, and to analyze their collective data - is transforming many industries. In mining, networked sensors are already used for remote operation, automation including driverless vehicles, health and safety, and exploration. In this paper, the state-of-the-art sensing and monitoring technologies are assessed as solutions against the main challenges and opportunities in the mining industry. Localization, mapping, remote operation, maintenance and health and safety are identified as the main beneficiaries, from rapidly developing technologies such as 3D visualization, augmented reality, energy autonomous sensor nodes, distributed sensing, smart network protocols and big data analytics. It is shown that the identification and management of ore grade in particular, which transcends each stage of the mining process, may critically benefit from certain arising sensing technologies, where major efficiency improvements are possible in exploration, extraction, haulage and processing activities.
Kiziroglou M, Becker T, Wright S, et al., 2016, Thermoelectric generator design in dynamic thermoelectricenergy harvesting, PowerMEMS 2016, Publisher: Institute of Physics (IoP), ISSN: 1742-6588
This paper reports an analysis of thermoelectric generator design for dynamic thermoelectric harvesting. In such devices, the available energy for a given temperature cycle is finite and determined by the heat storage unit capacity. It is shown by simulation and experimentally that specific thermoelectric generator designs can increase the energy output, by optimizing the balance between heat leakage and dynamic response delay. A 3D printed, doublewall heat storage unit is developed for the experiments. Output energy of 30 J from 7.5 gr of phase change material, from a temperature cycle between ± 22 °C is demonstrated, enough to supply typical duty-cycled wireless sensor platforms. These results may serve as guidelines for the design and fabrication of dynamic thermoelectric harvesters for applications involving environments with moderate temperature fluctuations.
Boyle D, Kiziroglou ME, Mitcheson P, et al., 2016, Energy provision and storage for pervasive computing, IEEE Pervasive Computing, Vol: 15, Pages: 28-35, ISSN: 1536-1268
Soon, pervasive computers will enormously outnumber humans. Devices requiring sufficient energy to operate maintenance-free for periods of years and beyond render today's technologies insufficient. With the gap between energy requirements of embedded systems and achievable levels of harvested power reducing, viable hybrid energy and power management subsystems have emerged that combine harvesting with finite, rechargeable energy buffers. Coupled with advances in wireless power transfer and energy storage, the authors suggest that an energy design space is emerging. There are, as yet, no tools or systematic methods for design space exploration or engineering in this context. It's important to develop such a methodology, and critical to link it with methodologies for system design and verification. The authors discuss key factors such an energy design methodology should incorporate, including size, weight, energy and power densities; mobility; efficiencies of harvesters and buffers; time between charges, (dis)charge speeds, and charge cycles; and availability and predictability of harvestable energy. This article is part of a special issue on energy harvesting.
Kiziroglou ME, Elefsiniotis A, Kokorakis N, et al., 2016, Scaling and super-cooling in heat storage harvesting devices, Microsystem Technologies, Vol: 22, Pages: 1905-1914, ISSN: 0946-7076
Aircraft sensors are typically cable powered, imposing a significant weight overhead. The exploitation of temperature variations during flight by a phase change material (PCM) based heat storage thermoelectric energy harvester, as an alternative power source in aeronautical applications, has recently been flight tested. In this work, the applicability of this technology to use cases with smaller and larger size specifications is studied by fabrication, testing and analysis of a scaled-down and a scaled-up prototype. Output energy of 4.1 J/g of PCM from a typical flight cycle is demonstrated for the scaled-down device, and 2.3 J/g of PCM for the scaled-up device. The higher energy density of the scaled down prototypes is attributed to the reduction in temperature inhomogeneity inside the PCM. The impact of super-cooling on performance is analyzed by employing a simulation model extended to include super-cooling effects. It is found that super-cooling may be beneficial for scaling down, in applications with slow temperature fluctuations.
Kiziroglou ME, Boyle D, Wright SW, et al., 2015, Acoustic energy transmission in cast iron pipelines, The 15th International Conference on Micro and Nanotechnology for Power Generation and Energy Conversion Applications (PowerMEMS 2015), Publisher: Institute of Physics (IoP), Pages: 1-5, ISSN: 1742-6588
In this paper we propose acoustic power transfer as a method for the remote powering of pipeline sensor nodes. A theoretical framework of acoustic power propagation in the ceramic transducers and the metal structures is drawn, based on the Mason equivalent circuit. The effect of mounting on the electrical response of piezoelectric transducers is studied experimentally. Using two identical transducer structures, power transmission of 0.33 mW through a 1 m long, 118 mm diameter cast iron pipe, with 8 mm wall thickness is demonstrated, at 1 V received voltage amplitude. A near-linear relationship between input and output voltage is observed. These results show that it is possible to deliver significant power to sensor nodes through acoustic waves in solid structures. The proposed method may enable the implementation of acoustic - powered wireless sensor nodes for structural and operation monitoring of pipeline infrastructure.
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