Energy Scavenging Research Articles

Surface Area Enhanced Nylon-6,6 Nanofiber Engineered Triboelectric Nanogenerator for Self-Powered Seat Monitoring Applications

High-performance triboelectric nanogenerators (TENG), generally comprised of either a pair of surface-functionalized or dielectric modulated composite frictional layers, are technically unreliable from a commercial perspective, because of the complex fabrication procedures and configurations. This work projects a surface area enforced electrospun Nylon-6,6-based TENG as the vibrational energy scavenging and seat occupation detection system. The devised TENG can derive an output response of more than 300 μA of short circuit current, 350 V of open circuit voltage, and a power density of 550 mW m–2, which is the highest compared to previously reported Nylon-based dielectric-metal contact separation-based TENGs. The seat occupation sensing was successfully evaluated during a test drive on the TENG fitted vehicle. The charging up of a 1 μF capacitor to ∼30 V in 30 s marks the potential of Nylon-6,6 as a promising material for many applications, including smart transit.

A high-applicability, high-durability wearable hybrid nanogenerator with magnetic suspension structure toward health monitoring applications

Wearable health monitoring is becoming increasingly significant due to the pursuit of high-quality life. However, wearable health monitoring devices powered by limited capacities batteries face frequent charging demand and unhandy device replacement. Effective energy scavenging from human locomotion is an alternative approach for powering wearable health monitoring devices. Herein, a novel wearable hybrid nanogenerator (WHG) combining soft-contact triboelectric nanogenerators (SC-TENGs) with three-phase suspension electromagnetic generators (TPS-EMGs) based on a distinctive magnetic suspension structure is designed to harvest human biomechanical energy. The features of frequency increase and automatic reset for the magnetic suspension structure are analyzed by finite element simulations. The SC-TENGs and TPS-EMGs can deliver the maximum instantaneous power of 0.54 mW and 1.81 mW, respectively. For efficiently employing the electric energy derived from the WHG, a power management integrated circuit was manufactured, which not only supplies a stable voltage to suit electronic devices, but also realizes multiple working modes to solve the power mismatch between the WHG and health monitoring applications with different power requirements. Furthermore, a self-powered bracelet with the function of heartbeat monitoring and a wearable blood glucose monitor linked to a smartphone are realized. This work indicates the huge potential of the WHG for powering real-time healthcare monitoring devices, which facilitates the development of self-powered wearable electronics.

Highly transparent and water-repellent hierarchical-wrinkled-architecture triboelectric nanogenerator with ultrathin plasma-polymer-fluorocarbon film for artificial triboelectric skin

For scavenging energy from various places on the human body, multifunctional and comfortable triboelectric nanogenerators (TENG), that do not stimulate sensitive skin, are required. Therefore, it is essential to fabricate a TENG that is easy to deformation as well as biocompatible, ultrathin, and flexible. In this regard, we propose a hierarchical-wrinkled-architecture-TENG (HWA-TENG) with dual-wavelengths (microsize of 3.1 µm and nanosize of 311.8 nm). A plasma-polymer-fluorocarbon (PPFC) thin film was employed as a high-performance triboelectrification material, owing to its high surface charge potential, ultrathin thickness, transparency, and water repellency. The surface potential of the PPFC was extremely high at 7.28, which is comparable to that of bulk polytetrafluoroethylene. The surface area of HWA-TENG increased by as much as 3.5 % owing to the combination of the increased surface area effect of the HWA and high surface charge potential characteristics of the PPFC thin film, resulting in a high output performance of 200 V and 30 μA. The HWA-TENG can be successfully applied to triboelectric raindrops energy harvester and conformal artificial triboelectric skin. Owing to its eco-friendly, straightforward fabrication process, and high output performance, HWA-TENG can be used in several applications, including conformal TENGs for human body.

MEMS based energy scavenger with interdigitated electrodes

MEMS-based energy scavengers have attracted industries and researchers as promising solutions to the energy crises which will certainly affect the present and future generations due to increased population and/or pollution. The capability of miniaturized energy scavengers to generate usable energy from ambient vibrations makes them a special and effective alternative to clean energy sources that can be used in many applications like point of care testing devices, and self-power micro-systems, low duty cycle applications, etc. MEMS-based energy scavenger using Zinc Oxide (ZnO) piezoelectric material for active layer is proposed here which can be used to drive the low power applications. The spin coating method with optimized speed was effectively used for ZnO deposition. Aluminum foil-based Interdigitated Electrodes (IDE) were used to ensure good flexibility, no internal defects, and crack-free movement during vibrations. The low-cost, easily available, flexible Polyethylene Terephthalate (PET) substrate used in the passive layer makes the scavenger suitable for energy harvesting from vibrations of many natural surface structures which are not flat such as clothes, human bodies, household equipment, industrial machines, etc. The MEMS-based Energy Scavenger with Interdigitated Electrodes (MEMS-ES-IDE) generated 3 V open-circuit voltage (OCV) at 60 Hz resonant frequency. Based on the obtained values of OCV, it was confirmed that the fabricated MEMS-ES-IDE would be used in a variety of low-duty cycle applications.

Water Droplet‐Based Nanogenerators

AbstractWater is one of the most sustainable resources in the world, offering an abundance of hydro energy. Getting a large amount of electricity through conventional water energy harvesting is expensive, with complex mechanisms and bulky installation systems. In the case of the small amount of energy for some portable electronic devices and sensor systems, water droplet harvesting as a sustainable energy resource has become a forward‐looking step to meet the future demand for green energy. The ultimate demand for green energy in the future requires all the possible sustainable energy sources surrounding human society. The emerging potential of water droplet‐driven energy‐harvesting nanogenerators can meet a significant portion of the green energy demand. In this review, the recent developments in droplets‐driven nanogenerators for effective energy scavenging is summarized. It also includes an extensive discussion about the device structures from the material selection and output performance aspects. This review also gives a brief discussion on the applications of droplet‐based nanogenerators and outlines the future possibilities via the current improvement in designs and fabrication strategies that have been introduced by the field.

MEMS-based energy scavengers: journey and future

MEMS-based energy scavengers: journey and future

Piezoelectric Energy Harvesting from Low-Frequency Vibrations Based on Magnetic Plucking and Indirect Impacts

This work proposes a mono-axial piezoelectric energy harvester based on the innovative combination of magnetic plucking and indirect impacts, e.g., impacts happening on the package of the harvester. The harvester exploits a permanent magnet placed on a non-magnetic mass, free to move within a predefined bounded region located in front of a piezoelectric bimorph cantilever equipped with a magnet as the tip mass. When the harvester is subjected to a low-frequency external acceleration, the moving mass induces an abrupt deflection and release of the cantilever by means of magnetic coupling, followed by impacts of the same mass against the harvester package. The combined effect of magnetic plucking and indirect impacts induces a frequency up-conversion. A prototype has been designed, fabricated, fastened to the wrist of a person by means of a wristband, and experimentally tested for different motion levels. By setting the magnets in a repulsive configuration, after 50 s of consecutive impacts induced by shaking, an energy of 253.41 μJ has been stored: this value is seven times higher compared to the case of harvester subjected to indirect impacts only, i.e., without magnetic coupling. This confirms that the combination of magnetic plucking and indirect impacts triggers the effective scavenging of electrical energy even from low-frequency non-periodical mechanical movements, such as human motion, while preserving the reliability of piezoelectric components.

Probing the Carrier Dynamics of Polymer Composites with Single and Hybrid Carbon Nanotube Fillers for Improved Thermoelectric Performance

The incorporation of carbon nanotubes (CNTs) within polymer hosts offers a great platform for the development of advanced thermoelectric (TE) composite materials. Over the years, several CNT/polymer composite formulations have been investigated on an effort to maximize the TE performance. Meanwhile, several studies focused on the decay dynamics of the charged excitons within CNTs itself and therefrom derived structures, aiming to investigate the lifetimes and the corresponding recombination processes of free charge carriers. The latter physical phenomena play a crucial role in the performance of various types of energy converting and scavenging materials. Nevertheless, up to this date, there is no systematic study on the combination of TE parameters and the critical charge carrier dynamics within CNT containing TE polymer composites. Herein, a variety of composites with single and hybrid CNT fillers based on polycarbonate (PC) and polyether ether ketone (PEEK) polymer matrices were prepared by melt-mixing in small scale. At the same loading, the addition of single fillers in PC results in higher Seebeck coefficients and similar conductivities when compared to the use of hybrid filler systems. In contrast, with hybrid filler systems in PEEK composites, higher power factors could be reached than in single filler composites. Moreover, the PC-based composites are studied using ultrafast laser time-resolved transient absorption spectroscopy (TAS), for the investigation of the exciton lifetimes and the physical origins of free charge carrier transport within the TE films. The findings of this study reveal interesting links between the TE parameters and the obtained charge carrier dynamics.

Development of a Nonlinear Harvesting Mechanism from Wide Band Vibrations

The main objective of this study is to present an energy harvesting approach to scavenge electrical energy from mechanically vibrated piezoelectric materials.A mechanical energy harvester device has been developed and tested. The fundamental benefit of this mechanical device is that it can function effectively in a wide range of ambient vibration frequencies, whereas traditional harvesters are limited. A suitable conditioning circuit for energy scavenging has been proposed which can achieve optimal power stream. For controlling the power flow into the battery a circuit has been designed consisting of an AC to DC rectifier, an output capacitor, a switch mode DC to DC converter, and an electromechanical battery. An adaptive control system has been described for switching any electronics devices and maximizing battery storage capacity. Experimental results reveal that the power transfer rate can be enhanced by approximately 400% by utilizing the adaptive DC to DC converter. Various investigations on the piezoelectric harvester have revealed that the energy generated by the mechanical device can exceed the 1.4-volt barrier, which is suitable for charging capacitors in electronics devices. The findings of this study will be crucial in mitigating society's energy crisis.

Energy scavenging on distribution network cables

For large scale monitoring on an electricity distribution network, it is desirable to have instrumentation that is self-powered to avoid the requirement for installing a mains 50Hz/60Hz plug socket to power the measuring device. This is particularly important if widescale monitoring is required, as the costs of installing a socket at each measurement location could add up to be significant. This paper reviews current state of the art energy scavenging and then suggests alternative ways of scavenging energy from the electricity distribution cables to be monitored. The paper investigates installing an energy scavenger which uses the energy in low frequency electromagnetic fields. The theory behind the measurement is explained along with a selection of different hardware setups. Around 25mW of ac power has been measured as being available. However, this is not yet at a level that is sufficiently useful to power a low cost microprocessor with mobile communications.

An Optimized Energy Harvesting Circuit for Low-Power IoT Applications

The concept and development of an independent energy harvesting mechanism functioning intermittently are described in this paper. A power management circuit (PMC) that is self-regulating, an energy scavenging module, a circuit for charging batteries, as well as an electronic load are all a component of the system that has been proposed. This proposed circuit is designed to attain a fixed output power with a diverse input range. In the unavailability of an additional voltage supply, the PMC can react, maintain, and smartly control the electronic load's power supply. The self-powered energy accumulating technique is expected to be used in situations when supplied power is inadequate to drive the load properly, such as Internet of Things (IoT) applications. IoT is a dispersed architecture of reduced-power, limited-storage, lightweight, and nodes that are adaptive. The majority of embedded IoT devices and low-power IoT sensors are driven by short-life batteries that must be replaced every few years. This procedure is expensive and efficient energy regulation could be critical in enabling energy savings for connecting IoT devices. Experiments with the proposed PMC show that the voltage stored in the capacitor remained mostly fixed at 3.3V at widely diverse inputs that vary from 850mV to 4V. At 3.5V input voltage, a peak efficiency of 88.67% is achieved while the load resistance considered is 230Ω.

Overlay Networks with Nonlinear Energy Scavenging and NOMA-Assisted Decoding: Security Performance Analysis

Overlay Networks with Nonlinear Energy Scavenging and NOMA-Assisted Decoding: Security Performance Analysis

Particle triboelectric nanogenerator (P-TENG)

Triboelectric nanogenerators (TENGs) have been rapidly studied for electromechanical energy scavenging and self-powered sensing. However, the limited research efforts have been devoted to utilizing tiny and irregular motions like from a human body and nature. Moreover, TENGs with multi-directional energy harnessing are rarely addressed so far. For the first time, this paper proposes a novel TENG by placing cellulose-based particles inside a rapidly degradable gelatin capsule to harvest electrical energy from all directional moving without conventional contact/separation requirements. The tiny cellulose particles (~6 µm) can generate triboelectric energy from low-frequency irregular motions, hence it is demonstrated as particle triboelectric nanogenerator (P-TENG). The proposed P-TENG device generates voltage from 15 to 85 V, current from 409 to 1326 nA, and power from 5.488 to 70 μW, when the device units increase from 1 to 16. Apart from these, the P-TENG presents maximum energy conversion efficiency up to 74.35% during vertical motion. Furthermore, it can produce energy in versatile scenarios from the various human body motions and other environmental usual movements. Hence, the proposed device can pave a new sight for low-level triboelectricity for self-powered electronic systems.

Global optimization of excitation directions for scavenging energy based on a cross-jointed L-shape multidirectional piezoelectric energy harvester

Energy harvesting technology can collect energy from environmental vibrations, but it is still challenging because the vibration from an environment is random and the directions vary. In this study, a novel cross-coupled L-shaped vibration piezoelectric energy harvester (CL-VPEH) was proposed to collect energy from different environmental vibration directions. This CL-VPEH consists of a vertical beam and a horizontal beam joint crosswise with two laminated piezoelectric layers. Finite element analysis was performed to study the voltage output and resonant frequency. A simplified lumped mass model of CL-VPEH under excitation from an arbitrary direction was built to describe its working principle and multi-directional energy-harvesting ability. The experimental results demonstrate that the CL-VPEH shows good agreement with the numerical and analytical solutions. The experimental results validate the CL-VPEH’s multidirectional energy harvesting ability. Using the lumped mass model, the performance of the CL-VPEH under every single-direction excitation is investigated. A weak power output area is found with a frequency range of 10 Hz − 25 Hz, which should be avoided in future applications of this kind of multiple-directional excitation energy harvesting.

Effect of Hardware Imperfections and Energy Scavenging Nonlinearity on Overlay Networks in $$\kappa -\mu $$ Shadowed Fading

Effect of Hardware Imperfections and Energy Scavenging Nonlinearity on Overlay Networks in $$\kappa -\mu $$ Shadowed Fading

Energizing Low Power Devices by Harvesting Energy from Ubiquitous Electromagnetic Wave Resources

In the recent years most of the devices are designed with low power consumption such as wearable devices, remote monitoring sensors, sensors used in fashionablecities. However, even long lasting batteries have a limited lifespan and must be replaced every few years. Replacements of batteries become costly when there are hundreds of sensors in rural areas.Technologies of Energy harvesting, on the other hand, provide infinite operating life of low-power equipment and avoid the need to replace batteries where it is costly, impractical or hazardous. Energy Harvesting (EH) is a process wherein the sources such as mechanical load, vibrations, temperature gradients and light, etc., serve as the resource from which the energy harvested and transformed to obtain relatively small levels of power in the range of nW-mW. The transducer converts one form of energy to other form usually electrical signal. The output obtained from the RF antenna is sent for power conditioning to ensure the operating frequency, voltage and current. The received RF signal is given to the matching network to provide proper impedance matching between the antenna and the signal conditioning circuit. The received RF signal is rectified and passed through the voltage multiplier circuit. In order to get sufficient output voltage to drive the device voltage quadrupler is used in the proposed system. As electromagnetic wave is available in surplus in our surrounding, it can be an uninterrupted resource for the energy generation for the device. Energy storage device is associated with the energy scavenging circuitry to enable the energy scavenged to be utilized for future purpose. The proposed system meets the state-of-the-art in the field of energy harvesting for low power devices using the RF energy harvesting.

Energy Harvesting: An Overview of Techniques for Use Within the Transport Industry

This article introduces the various energy harvesting mechanisms that can be used to energize sensing systems and associated wireless communication channels. It outlines energy scavenging techniques, along with an assessment of useful materials for each mode of harvesting.

Developments in Deep Brain Stimulators for Successful Aging Towards Smart Devices-An Overview.

This work provides an overview of the present state-of-the-art in the development of deep brain Deep Brain Stimulation (DBS) and how such devices alleviate motor and cognitive disorders for a successful aging. This work reviews chronic diseases that are addressable via DBS, reporting also the treatment efficacies. The underlying mechanism for DBS is also reported. A discussion on hardware developments focusing on DBS control paradigms is included specifically the open- and closed-loop “smart” control implementations. Furthermore, developments towards a “smart” DBS, while considering the design challenges, current state of the art, and constraints, are also presented. This work also showcased different methods, using ambient energy scavenging, that offer alternative solutions to prolong the battery life of the DBS device. These are geared towards a low maintenance, semi-autonomous, and less disruptive device to be used by the elderly patient suffering from motor and cognitive disorders.

A cantilever-type vibro-impact triboelectric energy harvester for wind energy harvesting

This paper presents a novel wind energy harvester utilizing galloping effect coupled with triboelectric-based energy conversion to convert the flow-induced structural vibration into electricity. The proposed harvester comprises a host cantilever beam, a stopper, and a middle plate with one rotation degree of freedom. The triboelectric layers and electrodes are placed in between the surface of the stopper and middle plate. A bluff body is fixed at the free end of the host beam to induce galloping vibration, which drives the middle plate to contact with the stopper periodically, thus generating electricity due to the triboelectric-based conversion mechanism. The proposed harvester can harness energy from wind velocity as low as 2 m/s depending on the selection of cantilever beams. A distributed coupled aero-electro-mechanical model is formulated to investigate the dynamic behavior of the harvester. The impact between the middle plate and stopper is found to have a significant influence on the energy generation performance of the harvester. Rigid impact could cause irregular and impulsive separation of contact surfaces, leading to sporadic voltage output. An optimal configuration is determined by selecting proper parameters of the stopper, bluff body, and gap distance in the design of the harvester. The proposed model shows good accuracy for modeling a moderate impact-engaged triboelectric harvester working on contact and separation mode. The fabricated harvester prototypes can produce a root mean square voltage of 12.8 V with a maximum power of 290 µW at wind velocity of 10 m/s. Even at low wind velocity, such as 6 m/s, the maximum power can reach up to 196 µW, demonstrating the promising energy scavenging capability of the proposed harvester.

Thermoelectric Inks and Power Factor Tunability in Hybrid Films through All Solution Process.

Thermoelectric (TE) materials can have a strong benefit to harvest thermal energy if they can be applied to large areas without losing their performance over time. One way of achieving large-area films is through hybrid materials, where a blend of TE materials with polymers can be applied as coating. Here, we present the development of all solution-processed TE ink and hybrid films with varying contents of TE Sb2Te3 and Bi2Te3 nanomaterials, along with their characterization. Using (1-methoxy-2-propyl) acetate (MPA) as the solvent and poly (methyl methacrylate) as the durable polymer, large-area homogeneous hybrid TE films have been fabricated. The conductivity and TE power factor improve with nanoparticle volume fraction, peaking around 60–70% solid material fill factor. For larger fill factors, the conductivity drops, possibly because of an increase in the interface resistance through interface defects and reduced connectivity between the platelets in the medium. The use of dodecanethiol (DDT) as an additive in the ink formulation enabled an improvement in the electrical conductivity through modification of interfaces and the compactness of the resultant films, leading to a 4–5 times increase in the power factor for both p- and n-type hybrid TE films, respectively. The observed trends were captured by combining percolation theory with analytical resistive theory, with the above assumption of increasing interface resistance and connectivity with polymer volume reduction. The results obtained on these hybrid films open a new low-cost route to produce and implement TE coatings on a large scale, which can be ideal for driving flexible, large-area energy scavenging technologies such as personal medical devices and the IoT.