106 results found
Wright SW, Kiziroglou ME, Yeatman EM, 2023, Inductive power line harvester with flux guidance for self-powered sensors, IEEE Sensors Journal, Vol: 23, Pages: 20474-20482, ISSN: 1530-437X
Self-powered sensors are expected to enable new large-scale deployment and location access capabilities for sensor systems. Energy harvesting devices have been shown to provide adequate power densities but their dependence on very specific environmental conditions restricts their applicability. Energy harvesting from power line infrastructure offers an architecture for addressing this challenge, because such infrastructure is widely available. In this paper an inductive power line harvester concept is presented, based on a flux concentration approach adapted to a closed-loop core geometry. Flux concentration is studied by simulation, showing a 26% flux increase using a 1:3 geometrical concentration ratio in a closed-loop core. A 20×20×25 mm prototype with a U-shaped soft-core sheet and a 200-turn Cu coil around a 5 mm diameter, 20 mm long soft-core rod is introduced. The total device volume is 9.1 cm 3 . Characterization results on a power line evaluation setup for currents up to 35 A RMS and a 50 Hz – 1 kHz range are presented. Power between 2.2 mW (50 Hz) and 233 mW (1 kHz) is demonstrated on an ohmic load, from a 10 A RMS power line current, employing impedance matching with reactance cancellation. The corresponding power densities are 0.24 mW/cm 3 and 25 mW/cm 3 respectively, per total device volume. This performance is adequate for enabling self-powered wireless sensor networks installed along power distribution lines.
Yang SKE, Kiziroglou ME, Yeatman EM, et al., 2023, Acoustic flow sensor using a passive bell transducer, IEEE Sensors Journal, Vol: 23, Pages: 20553-20560, ISSN: 1530-437X
Sensing based on a passive transducer that is wirelessly linked to a nearby data collection node can offer an attractive solution for use in remote, inaccessible, or harsh environments. Here we report a pipe flow sensor based on this principle. A transducer mounted inside the pipe generates an acoustic signal that is picked up by an external microphone. The passive transducer comprises a cavity with a trapped ball that can oscillate in response to flow. Its collisions generate an acoustic signal correlated to the flow speed. The transducer is implemented on a 6 mm diameter probe and characterized as a water flow meter. The time - average microphone voltage output is calculated by an analogue circuit, without any further signal processing. With the microphone mounted on the probe, and for flow rates in the range 0.35 m/s to 6.5 m/s, correlation between the sensor voltage output and flow rate data from a commercial flow meter is demonstrated with a worst-case accuracy of 2%. This was achieved by simple averaging of the acoustic pulse train over a 5-second time interval. Consistent correlation with the microphone mounted on the pipe wall at distances up to 150 mm from the probe location is also reported. These results demonstrate the viability of remote acoustic flow sensing using passive structures and offer a simple and minimally invasive flow monitoring method.
Blagojevic M, Dieudonne A, Kamecki L, et al., 2023, Autonomous electrical current monitoring system for aircraft, IEEE Transactions on Aerospace and Electronic Systems, Vol: 59, Pages: 3345-3358, ISSN: 0018-9251
Aircraft monitoring systems offer enhanced safety, reliability, reduced maintenance cost and improved overall flight efficiency. Advancements in wireless sensor networks (WSN) are enabling unprecedented data acquisition functionalities, but their applicability is restricted by power limitations, as batteries require replacement or recharging and wired power adds weight and detracts from the benefits of wireless technology. In this paper, an energy autonomous WSN is presented for monitoring the structural current in aircraft structures. A hybrid inductive/hall sensing concept is introduced demonstrating 0.5 A resolution, < 2% accuracy and frequency independence, for a 5 A – 100 A RMS, DC-800 Hz current and frequency range, with 35 mW active power consumption. An inductive energy harvesting power supply with magnetic flux funnelling, reactance compensation and supercapacitor storage is demonstrated to provide 0.16 mW of continuous power from the 65 μT RMS field of a 20 A RMS, 360 Hz structural current. A low-power sensor node platform with a custom multi-mode duty cycling network protocol is developed, offering cold starting network association and data acquisition/transmission functionality at 50 μW and 70 μW average power respectively. WSN level operation for 1 minute for every 8 minutes of energy harvesting is demonstrated. The proposed system offers a unique energy autonomous WSN platform for aircraft monitoring.
Becker T, Kiziroglou ME, Duffy M, et al., 2023, Industrial Adoption of Energy Harvesting: Challenges and Opportunities, IEEE POWER ELECTRONICS MAGAZINE, Vol: 10, Pages: 57-64, ISSN: 2329-9207
Chen X, Zhao J, Vyas K, et al., 2023, Origami-inspired flexure-based robot for endomicroscopy probe manipulation, The 22nd International Conference on Solid-State Sensors, Actuators and Microsystems, Publisher: IEEE
Probe-based confocal endomicroscopy (pCLE) is apromising imaging modality but requires precise andcontrolled scanning over the tissue surface, which issignificantly challenging to the operator. The paperpresents a 3D-printed origami-inspired miniature deltarobot for accurate manipulation of pCLE probe.Kinematics and Finite Element Analysis (FEA) simulationare conducted for a transfer matrix from the applied voltageto the displacement. An open-loop kinematiccharacterization based on the simulation was performed.The results demonstrate adequate repeatability andprecision, allowing the execution of various motions.Further 3D motion control will be achieved by employingvisual servoing.
Wright SW, Kiziroglou ME, Yeatman EM, 2023, Clamped closed-loop flux guides for power line inductive harvesting, 2022 21st International Conference on Micro and Nanotechnology for Power Generation and Energy Conversion Applications (PowerMEMS), Publisher: IEEE, Pages: 82-85
Inductive harvesting from existing power lines in vehicle, industrial and infrastructure environments offers an opportunity for providing energy autonomy to sensors in a wide range of environments with high sensing interest. Flux funnelling has been shown to improve the power density of such devices by over an order of magnitude. The requirement for retrofitting onto existing power lines leads to a demand for detachable magnetic core interfaces, which introduce gaps and uncertainty to device performance. In this paper, an inductive energy harvesting device design that addresses this challenge is introduced. The design allows the interfaces to be internal to the device housing. Repeatable fixing, with reduced sensitivity to installation practicalities and controllable force is achieved by a screw-pressing mechanism, and the employment of a hard polyoxymethylene housing material. This method is utilized in an inductive power-line prototype, demonstrating power output up to 260 mW from a 40 A RMS, 500 Hz current, emulating aircraft power lines.
Kiziroglou ME, Yeatman EM, 2023, Energy Harvesters and Power Management, More-than-Moore Devices and Integration for Semi Conductors, Pages: 1-46, ISBN: 9783031216091
Energy harvesting is a subset of Renewable Energy Technologies. It regards specifically the collection of small amounts of ambient energy, typically in the milliwatt range and below, for local use with the objective of providing energy autonomy to microsystems. In this chapter, an overview of the most common energy harvesting methods is presented, including motion, heat and electromagnetic field energy sources. A brief summary of solar, acoustic and radio frequency wave energy harvesting technologies is also presented. Finally, an overview of the main power management technologies developed and employed in energy harvesting is provided. The current state of the art provides adequate tools for developing energy autonomous microsystems in specific applications. Research focusing on integrating these technologies in low-power microchips, for energy autonomous operation in important application environments, such as on the human body or around a mobile phone, could enable new interactive capabilities for electronic information systems within the next 5 years.
Blagojevic M, Dieudonne A, Kamecki L, et al., 2023, The AMPWISE Project, Pages: 174-177
This paper presents an energy autonomous Wireless Sensor Network (WSN) for monitoring the structural current in aircraft structures. A hybrid inductive/hall sensing concept is introduced demonstrating 0.5 A resolution, 2% accuracy and frequency independence, for a 5 A-100 A Root-Mean-Square (RMS), DC-800 Hz current and frequency range, with 35 mW active power consumption. An inductive energy harvesting power supply with magnetic flux funneling, reactance compensation and supercapacitor storage is demonstrated to provide 0.16 mW of continuous power from the 65 uT RMS field of a 20 A RMS, 360 Hz structural current. A low-power sensor node platform with a custom multi-mode duty cycling network protocol is developed, offering cold starting network association and data acquisition/transmission functionality at 50 uW and 70 uW average power respectively. WSN level operation for 1 minute for every 8 minutes of energy harvesting is demonstrated.
Chen X, Halvorsen E, Kiziroglou ME, et al., 2023, A Position Control Modeling Method for an Origami-Inspired Flexure-Based Piezoelectric-Actuated Manipulator, Pages: 171-174
The manuscript presents a modelling method for position control of a piezoelectric-Actuated compliant mechanism. The method involves pseudo-rigid body (PRB) theory, linear electromechanical model of piezoelectric benders and Simulink-based simulation. In order to validate the modelling method, two experiments were designed and conducted. They are working volume estimation and voltage clip recurrence. The comparison between simulation and experimental results indicates that the modelling can predict the motion of the compliant structure and be used for optimization design. In future work, the model can be extended to include the hysteresis model of piezoelectric materials. Besides, the model can be applied together with an onboard visual feedback system to carry out a closed-loop control for higher precision motion.
Ge I, Jiang Y, Dankwort T, et al., 2023, MEMS AlN Piezoelectric Beams with Integrated NdFeB Magnets for Power Line and Rotational Motion Energy Harvesting, Pages: 122-125
On-chip power autonomy is a central objective of energy harvesting technologies. The integration of piezoelectric and magnetic materials with silicon-processing could address proof-mass size and broadband motion operation limitations. In this work, a MEMS device combining a silicon-based, AlN piezoelectric beam with an integrated NdFeB tip magnet is proposed as an energy harvesting transducer. The device is evaluated for rotational motion and power line energy harvesting use cases. In the rotational motion evaluation, a voltage output peak of 0.35 V is demonstrated from a permanent magnet passing at 4 mm distance. In the power line evaluation, an output power delivery of 5 μW on an ohmic load is demonstrated, at 10 mm distance from a power line carrying an RMS current of 13 A. These results show promising performance towards micro-chip integrated energy autonomy, suitable for time-varying magnetic field and relative structural motion environments.
We report a miniaturized wet-wet differential pressure sensor with applications in pressure and flow sensing in water networks and other harsh environments. The device is similar in concept to a conventional wet-wet differential pressure sensor in that the sensing element is protected from the external environment by oil-filled cavities closed off by corrugated diaphragms. However, with a package envelope of 11.0 x 4.8 x 3.4 mm 3 , corresponding to a volume of only 0.18 cm 3 , the device is considerably smaller than commercially available wet-wet differential pressure sensors. A high degree of miniaturization has been achieved by using micromachining to fabricate the corrugated diaphragms. Preliminary experimental results are presented showing operation of the device as a delta-pressure flow speed sensor in a water flow test rig.
Chen X, Kiziroglou ME, Yeatman EM, 2022, Linear displacement and force characterisation of a 3D-printed flexure-based delta actuator, Smart Materials and Structures, Vol: 31, Pages: 1-9, ISSN: 0964-1726
Piezoelectric beams provide a fast, high-force and scalable actuation mechanism that could offer precise motion control to medical microdevices including invasive micromanipulators, catheters and diagnosis tools. Their small displacement range can be addressed by motion amplification mechanisms. In this paper, a piezoelectric-actuated delta-robot actuator is proposed for probe-based confocal laser endomicroscopy (pCLE) microsystems. A prototype is designed and fabricated using three-dimensional (3D) polymer compound printing for a multi-flexure compliant motion amplifier and commercial piezoelectric beams. The flexure material is optimised for maximum linear output motion. The overall robot length is 76 mm and its maximum lateral dimension is 32 mm, with 10 g overall mass, including three piezoelectric beams. An axial motion control range of 0.70 mm and a maximum axial force of 20 mN are demonstrated, at 140 V actuation voltage. The proposed actuator architecture is promising for controlling lens, fibre and micromanipulator components for medical microrobotic applications.
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.
Kiziroglou ME, Wright SW, Yeatman EM, 2022, Power supply based on inductive harvesting from structural currents, IEEE Internet of Things Journal, Vol: 9, 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.
Yang S, Kiziroglou M, Yeatman E, et al., 2021, Passive acoustic transducer as a fluid flow sensor, IEEE Sensors Conference, Publisher: IEEE, Pages: 1-4
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.
Wright SW, Kiziroglou ME, Yeatman EM, 2021, Magnetic flux guidance using H structures for miniature transducers, 2021 IEEE 20th International Conference on Micro and Nanotechnology for Power Generation and Energy Conversion Applications (PowerMEMS), Publisher: IEEE, Pages: 156-159
Limited magnetic flux has been a significant restriction in the applicability of scaled-down inductive energy, sensing and actuating devices. Magnetic flux concentration could potentially address this challenge by offering higher flux density B and thereby higher transduction power density, sensitivity and force in the small scale. In this paper, a study of flux concentration from a flux path perspective is presented. Numerical simulations show that high permeability cylindrical cores can achieve a flux concentration ratio in the scale of their aspect ratio, as they gather flux from their reachable vicinity. Flux guiding structures such as H-shapes can concentrate the flux incident to their surface and guide it through a small cross-section, achieving a higher concentration ratio. In an experimental study, a flux concentration factor of 6 is reported using a single 5 mm diameter, 20 mm high cylinder, and an additional increase factor of 4.3 from the addition of 70 mm × 12 mm × 2 mm flanges. A total B amplification ratio of 26 is demonstrated. As an application demonstrator, this approach is employed in an inductive energy harvester yielding 11.4 mW average power output (0.3 mW/g) from a 0.12 mT RMS, 800 Hz field.
Chen X, Kiziroglou ME, Yeatman EM, 2021, Evaluation platform for MEMS-actuated 3D-printed compliant structures, 2021 IEEE 20th International Conference on Micro and Nanotechnology for Power Generation and Energy Conversion Applications (PowerMEMS), Publisher: IEEE, Pages: 188-191
This paper presents experimental results on an evaluation platform for MEMS-actuated compliant structures. A combination of 3 dimensional (3D) flexure design, 3D printing of polymers with controlled stiffness is employed. A modular system design approach allows the interchange and combination of different actuation cantilevers, flexures and structure designs implemented as standalone test parts with minimal assembly requirements. The performance evaluation method includes synchronised electrical excitation and optical displacement measurements, allowing characterisation of motion amplification, dynamic response as well as actuating power transfer. As a demonstrator, a single lever compliant structure was designed, fabricated and tested on the platform to investigate how geometry and material stiffness affect performance. The experimental results reveal that significant improvement of amplification ratio and absolute phase lag can be achieved by selecting a flexure height and material composition suitable for a given application. This method of combined experimental evaluation and custom 3D design and printing is promising for optimising the design of compliant structures for MEMS sensors, actuators and energy transducers with amplified or translated motion capability.
Pandiyan AYS, Kiziroglou ME, Yeatman EM, 2021, Complex impedance matching for far-field acoustic wireless power transfer, 2021 IEEE 20th International Conference on Micro and Nanotechnology for Power Generation and Energy Conversion Applications (PowerMEMS), Publisher: IEEE, Pages: 44-47
In this study, different load matching techniques are analysed to identify the optimum method to deliver power to the receiver for acoustic wireless power transfer systems. Complex impedance matching of the system’s transducers provides an advantage to drive the transmitter off-resonance for cases where there is a resonance mismatch between the transducers due to make, defect or ambient conditions. By studying the effect of impedance matching for different frequencies near the resonance frequency, similar power levels can be achieved for a wider bandwidth of frequencies using complex impedance matching. Thus, increased power can be delivered to the receiver by controlling the frequency of the transmitter, which can be exploited for beam steering along the propagation axis when standing waves are prominent between the transducers. A summary of the power experimentally extracted for the different loading techniques presented in this paper demonstrates a 4 kHz increase in system bandwidth and 140% more power can be delivered by tuning both transducers with complex impedance matching.
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
Kiziroglou ME, 2021, Powering Cyber-Physical-System nodes by Energy Harvesting, Heterogeneous Cyber Physical Systems of Systems, Pages: 235-252, ISBN: 9788770222020
Pollak MR, Kiziroglou ME, Wright SW, et al., 2021, Cold-Starting Switched-Inductor Bipolar Power Management for Dynamic Thermoelectric Harvesting, 20th International Conference on Micro and Nanotechnology for Power Generation and Energy Conversion Applications (PowerMEMS), Publisher: IEEE, Pages: 116-119
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.
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, Pages: 1-4
Ultrasonic Power Transmission (UPT) has gained attention for powering implanted diagnostic devices due to its non-invasive properties. However, UPT in free-space is still less exploited with considerable potential for powering Wireless Sensor Networks (WSNs). An important challenge in understanding the significant parameters for a UPT system is to comprehend the losses and quantify the limitations of the technology in terms of distance, frequency and transmission power (ISO226). In this work, the authors attempt to model the transmission link of an UPT system, identifying variables which can be modified for obtaining maximum power output from the wireless power transfer through formulation and experimental results. Ultrasonic transducers of two varying frequencies were used in free space power transmission to understand the absorptive and geometric attenuation of sound waves in air, experimentally. A measured power of 6.3μW(40kHz) and 8. 3nW(100kHz) was observed over 30cm. These observations may enable acoustic powered WSNs in automobiles powering multi-nodes using single transmitter.
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, Pages: 1-4
Motivated by recent developments in Wireless Power Transfer (WPT), this work presents a solution for the optimization of a two-stage energy distribution system combining inductive and acoustic power transfer using a clustering algorithm. A network of immobile wireless sensors equipped with acoustic transceivers, storage capacitors and with known cartesian coordinates in a 2D plane is considered. A power delivery vehicle (PDV) with finite energy storage capacity is used to recharge a sensor node's supercapacitor which then transmits power to neighboring sensors acoustically within range. This work aims to find an optimal charging route for the PDV. The proposed algorithm is a combination of cluster analysis and breadth-first search. A theoretical study was performed, and the simulation results obtained were studied for the long-term failure probability for the proposed energy scheme.
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
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