312 results found
Barbot A, Wales D, Yeatman E, et al., 2021, Microfluidics at fibre tip for nanolitre delivery and sampling, Advanced Science, ISSN: 2198-3844
Delivery and sampling nanolitre volumes of liquid can benefit new invasive surgical procedures.However, the dead volume and difficulty in generating constant pressure flow limits the use of small tubes such as capillaries.This work demonstrates sub-millimetre microfluidic chips assembled directly on the tip of a bundle of two hydrophobic coated 100 μm capillaries to deliver nanolitre droplets in liquid environments.Droplets are created in a specially designed nanopipette and propelled by gas through the capillary to the microfluidic chip where a passive valve mechanism separates liquid from gas, allowing their delivery.By adjusting the driving pressure and microfluidic geometry we demonstrate both partial and full delivery of 10 nanolitre droplets with 0.4 nanolitre maximum error, as well as sampling from the environment.This system will enable drug delivery and sampling with minimally invasive probes, facilitating continuous liquid biopsy for disease monitoring and in-vivo drug screening.
Lan L, Polonelli T, Qin Y, et al., 2020, An induction-based localisation technique for wirelessly charged drones, Pages: 275-277
This manuscript proposes a technique to use an inductive power transfer system to perform last-stage localisation of drones for tracking and automated landing. This system is proposed to assist the final stage of landing by solely making use of the inductive charger and avoid using vision or other external sensors which would increase cost and complexity.The simplicity of the proposed method can help widen the practical implementation of automated drones. This proposed method is demonstrated with a high frequency (6.78 MHz) inductive charging system that can deliver up to 100 W of power to a DJI M100 drone when it lands at any position on the designed one-meter diameter charging pad.
Pandiyan A, Boyle D, Kiziroglou M, et al., 2020, Optimal dynamic recharge scheduling for two stage wireless power transfer, IEEE Transactions on Industrial Informatics, Pages: 1-1, 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.
Li B, Tan H, Jenkins D, et al., 2020, Clinical detection of neurodegenerative blood biomarkers using graphene immunosensor, Carbon, Vol: 168, Pages: 144-162, ISSN: 0008-6223
Accurate detection of blood biomarkers related to neurodegenerative diseases could provide a shortcut to identifying early stage patients before the onset of symptoms. The specificity, selectivity and operational requirements of the current technologies, however, preclude their use in the primary clinical setting for early detection. Graphene, an emerging 2D nanomaterial, is a promising candidate for biosensing which has the potential to meet the performance requirements and enable cost-effective, portable and rapid diagnosis. In this review, we compare graphene-based immunosensing technologies with conventional enzyme-linked immunosorbent assays and cutting-edge single molecule array techniques for the detection of blood-based neurodegenerative biomarkers. We cover the progress in electrical, electrochemical and optical graphene-based immunosensors and outline the barriers that slow or prevent the adoption of this emerging technology in primary clinical settings. We also highlight the possible solutions to overcome these barriers with an outlook on the future of the promising, graphene immunosensor technology.
Liu H, Fu H, Sun L, et al., 2020, Hybrid energy harvesting technology: From materials, structural design, system integration to applications, Renewable and Sustainable Energy Reviews, Pages: 110473-110473, ISSN: 1364-0321
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, 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.
Polonelli T, Qin Y, Yeatman E, et al., 2020, A flexible, low-power platform for UAV-based data collection from remote sensors, IEEE Access, Vol: 8, Pages: 164775-164785, ISSN: 2169-3536
This article presents the design and characterisation of a new low-power hardware platform to integrate unmanned aerial vehicle and wireless sensor technologies. In combination, these technologies can overcome data collection and maintenance problems of in situ monitoring in remote and extreme environments. Precision localisation in support of maximum efficiency mid-range inductive power transfer when recharging devices and increased throughput between drone and device are needed for data intensive monitoring applications, and to balance proximity time for devices powered by supercapacitors that recharge in seconds. The platform described in this article incorporates ultra-wideband technology to achieve high-performance ranging and high data throughput. It enables the development of a new localisation system that is experimentally shown to improve accuracy by around two orders of magnitude to 10 cm with respect to GNSS and achieves almost 6 Mbps throughput in both lab and field conditions. These results are supported by extensive modelling and analysis. The platform is designed for application flexibility, and therefore includes a wide range of sensors and expansion possibilities, with source code for two applications made immediately available as part of a open source project to support research and development in this new area.
Shi M, Holmes A, Yeatman E, 2020, Piezoelectric wind velocity sensor based on the variation of galloping frequency with drag force, Applied Physics Letters, Vol: 116, ISSN: 0003-6951
In this paper, we demonstrate a miniature energy harvesting wind velocity sensor of simple, low-cost construction, based on a single-degree-of-freedom galloping structure. The sensor consists of a prismatic bluff body with a triangular cross section attached to the free end of acantilever incorporating a commercial polyvinylidene fluoride piezoelectric film. In the wind, the bluff body causes vibration of the cantileverbased on galloping, and the piezoelectric film converts the vibration energy into an electrical signal. We have observed a negative correlationbetween the wind velocity and the vibration frequency, and we demonstrate that this relationship can be used to detect wind velocity directlywith useful accuracy. A simple theoretical model indicates that the frequency shift can be accounted for by the effect of the axial loading dueto form drag. The model shows close agreement with the experimental results. In wind tunnel tests, a prototype wind velocity sensor basedon this principle could measure wind velocities from 4.45 to 10 m/s, with the measured velocity typically being within 4% of the referencevalue obtained using a Pitot tube.
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.
Kang M, Yeatman E, 2020, Coupling of piezo- and pyro-electric effects in miniature thermal energy harvesters, Applied Energy, Vol: 262, ISSN: 0306-2619
Thermal energy harvesting from ambient heat into electricity is of interest due to its wide potential applicability. This paper demonstrates a moving beam thermal energy harvesting mechanism exploiting both pyro- and piezo-electric effects simultaneously, for use adjacent to a heat source with small temperature variations at low frequency (below 0.1 Hz). For the first time, the relative contributions of these two mechanisms in such a device is established both theoretically and experimentally, and a dynamic model is provided. The relative phase of the contributed currents is shown to be a critical factor, and methods are introduced to optimise this phase relationship, particularly by selection of the mechanical configuration. The reported prototype achieves around 0.4 for a temperature difference of around 15 K at frequency 0.02 Hz with an optimal condition in the fixed-fixed configuration about 90% above the fixed-free end configuration.
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
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
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
Fu H, Song W, Qin Y, et al., 2020, Broadband Vibration Energy Harvesting from Underground Trains for Self-Powered Condition Monitoring, 19th International Conference on Micro and Nanotechnology for Power Generation and Energy Conversion Applications (Power MEMS), Publisher: IEEE
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
Qin Y, Boyle D, Yeatman E, 2019, Efficient and reliable aerial communication with wireless sensors, IEEE Internet of Things Journal, Vol: 6, Pages: 9000-9011, ISSN: 2327-4662
This paper describes the design, implementation and evaluation of a first of its kind cross-layer protocol for wireless communication between flying agents and terrestrial wireless sensors. The protocol is composed of three layers: a new application layer built upon a modified implementation of ContikiMAC over the IEEE 802.15.4 2.4 GHz physical layer. The experimental evaluation shows the protocol to have excellent energy efficiency, low latency and high reliability-approaching 100% for certain parameter settings and operational conditions. The effects of speed, altitude, and direction of approach are also experimentally evaluated, demonstrating that it is of critical importance to take these into account when planning mobile aerial data collection campaigns.
Fu H, Yeatman E, 2019, Rotational energy harvesting using bi-stability and frequency up-conversion for low-power sensing applications: Theoretical modelling and experimental validation., Mechanical Systems and Signal Processing, Vol: 125, Pages: 229-244, ISSN: 0888-3270
Abstract Kinetic energy harvesting has drawn great attention in the past decade, but low-frequency and broadband operation is still a big issue which impedes this technology to be widely deployed in low-power Internet of Things applications. In this paper, theoretical modelling and experimental validation of a rotational harvester with bi-stability and frequency up-conversion is presented for harnessing low-frequency kinetic energy with a wide bandwidth. Piezoelectric transduction was adopted to convert the rotational kinetic energy into electricity. Distributed-parameter modelling was employed for analyzing the electromechanical dynamics of the bistable piezoelectric beam. Bistable and frequency up-converting behaviours were considered in the theoretical model by introducing two external input magnetic forces. Different oscillating modes were analyzed, showing the variation of power generation capability under different modes, and the advantage of operating in the periodic double-well mode. From the potential well study, we got a conclusion that for the same input magnetic force, periodic double-well mode is capable of achieving a larger vibration amplitude compared to a harvester without bi-stability. Asymmetric potential well shapes were investigated. This asymmetric shape provides a way to stabilize the initiation position of the beam for each plucking cycle, and eventually to stabilized the output. Key design factors to control the oscillating modes were studied, providing a guideline for future design. An experimental study was conducted to verify the theoretical results. A close match was achieved. This bistable harvester demonstrated a significant improvement (up to 2 × ) compared to a harvester without bi-stability over a wide bandwidth (from 1 to 11 Hz) at low frequencies, when operating in the periodic double-well mode. This paper presents a detailed theoretical model and in-depth analysis of a bistable frequency up-converting harvester, providing a
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, Pages: 202-204
This paper proposes a new way to energize wireless sensors combining inductive power transfer with onward acoustic power distribution. Recent results showing inductive transfer of tens of watts from unmanned aerial vehicles to wireless sensors, in addition to acoustic propagation providing useful levels of transduced power, i.e. tens of mW, can be combined to form a hybrid wireless power transfer system for deeply embedded wireless sensors. Particular emphasis is placed on rectification efficiency for the acoustic receiver, finding that a minimum of 400 μW (for given parameters) are required to avoid excessive rectification losses, which is significant considering the finite energy available from the intermediate energy store.
Fu H, Zhou S, Yeatman E, 2019, Exploring coupled electromechanical non-linearities for broadband energy harvesting from low-frequency rotational sources, Smart Materials and Structures, Vol: 28, ISSN: 0964-1726
This paper presents a methodology to effectively harness low-frequency broadband rotational energy using coupled electromechanical non-linearities. This design integrates bi-stability and a synchronized switch harvesting on inductor (SSHI) circuit into a frequency up-converting harvester. The bistable behaviour enables improved output power due to the increased vibration amplitude under the same input plucking force. The SSHI circuit exhibits enhanced conversion capability, contributing higher electrical damping which is ideal for frequency up-converting harvesters to alleviate output fluctuation at high frequencies. To study the coupled non-linear dynamics from both the mechanical (bi-stability) and electrical (SSHI) sides, a system-level theoretical model is, for the first time, established and numerically solved using Matlab/Simulink. System behaviours, which would not be able to obtain using circuit simulation methods, are studied for different operating frequencies and load resistances. To validate the theoretical analysis, this harvester was implemented and tested experimentally. A close match was obtained. From the experimental results, an enhanced output power (up to 525%), over a broad frequency range, was realized, compared to that of a harvester with neither bi-stability nor SSHI circuits.
Gramling HM, Towle CM, Desai SB, et al., 2019, Spatially Precise Transfer of Patterned Monolayer WS2 and MoS2 with Features Larger than 10(4) mu m(2) Directly from Multilayer Sources, ACS APPLIED ELECTRONIC MATERIALS, Vol: 1, Pages: 407-416, ISSN: 2637-6113
Kang M, Yeatman EM, 2019, Hybridized thermal energy harvesting mechanism, 18th International Conference on Micro and Nanotechnology for Power Generation and Energy Conversion Applications, Publisher: IOP PUBLISHING LTD, ISSN: 1742-6588
Shi M, Yeatman EM, Holmes AS, 2019, Energy Harvesting Piezoelectric Wind Speed Sensor, 18th International Conference on Micro and Nanotechnology for Power Generation and Energy Conversion Applications, Publisher: IOP PUBLISHING LTD, ISSN: 1742-6588
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.
Qin Y, Boyle D, Yeatman E, 2019, Radio Diversity for Heterogeneous Communication with Wireless Sensors, 5th IEEE World Forum on Internet of Things (IEEE WF-IoT), Publisher: IEEE, Pages: 955-960
Fu H, Yeatman E, 2018, Comparison and scaling effects of rotational micro‐generators using electromagnetic and piezoelectric transduction, Energy Technology, Vol: 6, ISSN: 2194-4296
Rotational energy is widely distributed or easily acquirable from other energy sources (fluid flow, machine operation or human motion) in many industrial and domestic scenarios. At small scales, power generation from such rotational ambient sources can enable many autonomous and self‐reliant sensing applications. In this paper, three typical types of micro‐generators (energy harvesters), namely electromagnetic (EMREHs), piezoelectric resonant (PRREHs) and piezoelectric non‐resonant rotational energy harvesters (PNRREHs) are discussed and compared in terms of device dimensions and operation frequencies. Theoretical models are established for each type to calculate maximum achievable output power as a function of device dimension and operating frequency. Using these theoretical models, scaling laws are established for each type to estimate the achievable output. The EMREHs have a strong scaling effect both on device dimension (as L5) and on operating frequency (as ω2), whereas the PNRREHs are less so (L2.5ω0.5). PRREHs have a narrow band‐width as resonant harvesters, and are ideal for cases where the excitation frequency is constant. This study provides a guideline for selection and design of rotational energy harvesters (REHs) when the device dimension and operating frequency are defined. The proposed scaling laws offer a convenient method to estimate the harvester performance for different dimensions and operating frequencies.
Fu H, Yeatman EM, 2018, Effective piezoelectric energy harvesting using beam plucking and a synchronized switch harvesting circuit, Smart Materials and Structures, Vol: 27, ISSN: 0964-1726
Piezoelectric energy harvesting, as a way to convert kinetic energy into electricity for low-power electronics, has drawn great attention for the last decade. However, issues still remain, including narrow operating bandwidth and low harvesting capability. In this paper, beam plucking (frequency up-conversion) and a parallel synchronized switch harvesting on inductor (P-SSHI) circuit are integrated in a piezoelectric energy harvester to improve the energy harvesting capability over a wide operating bandwidth. A theoretical model for the plucked beam is established using a distributed-parameter method. In order to study the system dynamics, an equivalent circuit for the plucked beam is built to integrate with the P-SSHI circuit. System dynamics, including the input power, beam tip displacement and output power, are investigated for different driving frequencies and load resistance. The plucked beam provides a uniform and single-frequency vibration for the P-SSHI to generate reliable switching events for any low-frequency wideband vibration; the P-SSHI circuit exhibits an improved electrical damping ratio which is beneficial to alleviating the power fluctuation issue for plucked beams at high frequencies. An experimental validation was conducted, and a close match was obtained. Enhanced output power with low power fluctuation was obtained in the Plucked Beam and P-SSHI circuit (PBPS) configuration over a wide frequency bandwidth with constant load resistance.
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.
Mitcheson PD, Kkelis G, Aldhaher S, et al., 2018, Power Electronics for Wireless Power Delivery in Synthetic Sensor Networks, 17th International Conference on Micro and Nanotechnology for Power Generation and Energy Conversion Applications (PowerMEMS), Publisher: IOP PUBLISHING LTD, ISSN: 1742-6588
This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.