Self-powered Applications Research Articles

A novel vibration energy harvester based on eccentric semicircular rotor for self-powered applications in wildlife monitoring

Wildlife monitoring has become increasingly crucial for better examination and protection of wildlife. However, existing monitoring devices are limited and less effective due to battery life limitations. This paper proposes a novel vibration energy harvester (VEH) for self-powered applications in wildlife monitoring. An eccentric semicircular rotor was designed and developed to effectively convert the random movements of wild animals into energy. The proposed vibration energy harvester mainly consists of four components: vibration input module, electromagnetic generation module, power management module, and work module. The electromagnetic power generation module converts the kinetic energy of wildlife harvested by the eccentric semicircular rotor into electrical energy. The power management module converts the generated AC power into DC power; the electricity is stored in a lithium battery to provide power for the wildlife monitoring system. Experiments were conducted to record the harvested power from human and animal kinetic energy. The installed VEH on the leg of the tester produced 25.8 mW output power at the speed of 15 km/h, whereas sika deer resulted in 19.66 mW while running. Finally, an estimation analysis was conducted for sika deer, and found that 212.08 J/day can be harvested for the wildlife tag to work for 15 days.

Towards self-powered technique in underwater robots via a high-efficiency electromagnetic transducer with circularly abrupt magnetic flux density change

In this article, we present a high-efficiency electromagnetic transducer harvesting kinetic energy from the ocean current for self-powered technique in underwater robots to tackle the electric energy replenishment problem. A circular magnet array with alternating magnet arrangement was employed for providing a sudden change in magnetic flux density. A gear train was introduced into the compact design to greatly increase the rotation speed of the rotor. The finite element method is used to simulate and compare the magnetic flux density distributions and the induced voltages in the coil under different magnet arrays (conventional Halbach magnet array and proposed alternating one) with different magnet dimensions and numbers. The finite element method analysis shows that the alternating array displays a much larger changing magnetic flux density rate resulting in high induced electromotive forces. The experimental results based on a fabricated prototype indicate that the transducer yields maximum average output power of about 0.51 W with an energy conversion efficiency of 30.91% under the water flow speed of 0.64 m/s with a load resistance of 1 kΩ. We also investigated the capability of the transducer for self-powered applications in underwater robots. The transducer charged a 20 mF capacitor from 0 V to 29 V in 50 s. Also, the prototype charged a lithium battery embedded inside an underwater robot by 75% within 400 s. This study, with a broad application prospect, can advance the future development of self-powered underwater robotic systems.

A hybrid piezoelectric-electromagnetic wave energy harvester based on capsule structure for self-powered applications in sea-crossing bridges

The ocean is a huge kinetic energy field with considerable energy harvesting potential. Harvesting renewable ocean wave energy and using it to power electric facilities such as sensors for sea-crossing bridges in real time could be an effective strategy to promote sustainable development of the oceans. In this paper, we propose a piezoelectric-electromagnetic wave energy harvester (PEWEH) based on a sealed capsule structure for self-powered applications in sea-crossing bridges. The proposed system consists of three main components: piezoelectric module, electromagnetic module, and energy storage module. The piezoelectric module is mainly composed of two piezoelectric sheets which can be deformed by continuous wave motion to generate electricity. The electromagnetic module includes a fixed coil and a core that moves back and forth to cut the magnetic line to generate electricity. The electrical energy recovered by the piezoelectric module and electromagnetic module will be stored in the energy storage module after being rectified and stabilized. Experiment results showed that output voltage up to 7 V and power of 162 mW can be obtained by the PEWEH, validating that the proposed wave energy harvesting system is promising for self-powered applications in low-power monitoring sensors for sea-crossing bridges.

A hybrid wind and rainwater energy harvesting system for applications in sea-crossing bridges

As one of the essential types of clean energy, renewable energy has great potential to achieve the self-powered of wireless sensor. The health of the bridge depends mainly on the lifetime of the sensor. Therefore, it is of great significance to use renewable energy to achieve self-powered application of bridges. In this paper, a hybrid wind energy and rainwater energy harvester (WEREH) system for a self-powered sea-crossing bridge is presented. The proposed WEREH is installed on the drainpipe on the pier of the sea-crossing bridge. The system mainly includes three modules: energy collection module, energy conversion module, and energy storage module. The energy collection module is composed of S-rotor and water wheel. The energy conversion module is made up of a PVDF film array and magnet array. Electric energy can be obtained by the methods in which the PVDF films strike the adjustable plate and the changing magnetic field excites the coil. When only windy weather or only rainy weather is available, the S-rotor and water wheel are used to collect wind energy or rainwater energy, respectively. When it is windy and rainy mixed weather, the energy conversion module can keep working via one-way bearings. What is more, the S-rotor and water wheel can be flexibly combined with the energy conversion module to collect wind energy and rain energy, respectively. Finally, the power storage module stores the electricity by supercapacitors and the electric energy will be used to supply power for the low-power sensor of the sea-crossing bridge. Both simulations and experiments are performed to validate the feasibility and suitability of the system. Experimental results show that maximum output power can reach 2196.7 μWat the wind speed of 12 m/s and 245.76 μWat the flow rate of 18 L/min. Under the same condition, the maximum electric energy of the WEREH can reach 8659.76 μJin windy weather and 811.35 μJin rainy weather in a sweep process (6s). According to potential energy analysis, the annual electricity generated by each WEREH device can supply power for a displacement sensor (KTC1/LWH) for at least 239.95 days and a low-power temperature sensor (Si705x) for 254809.18 days at most.

Self-Powered Diagnostic System for AC Machines Based on Inhomogeneity of Magnetic Field Distribution in Air Gap

This article presents a self-powered system for supplying rotor measurement equipment and detecting stator winding inter-turn short circuit, and broken rotor bar faults in AC Machines. This system uses harvesting coils to harvest air-gap magnetic field pulsation and generate energy for powering equipment installed on the rotor. Furthermore, installing this system on the stator or rotor of AC machines provides a voltage signal appropriate for fault detection purposes. To determine specifications of the harvesting coils – coils turn numbers, and their optimal mounting positions – numerous finite element simulations have been carried out. In addition, a fault detection method has been proposed to detect broken rotor bar and inter-turn short circuit faults using induced voltage in the harvesting coils. To verify the performance of the proposed system, some experimental and simulation tests have been performed on various AC machines. The results have confirmed the applicability of this system in self-powering applications and fault detection purposes.

(Invited) Solid-Liquid Contact Electrification and Its Use for Energy Harvesting and Self-Powered Applications

The abundance of water on earth provides a large window to utilize the mechanical energy within river currents and ocean waves. In this regard, hydropower harvesting through solid–liquid contact electrification has received considerable interest in the recent past. Despite advancements in nanotechnology, liquid energy harvesting devices, especially solid–liquid triboelectric nanogenerators (S–L TENGs), require efficient engineering of the interfacial properties of their substrates to transfer liquid mass and momentum rapidly with the effective generation/transfer of surface charges. To face this challenge, several parameters such as the selection of material, surface morphology and surface properties are currently being studied to develop a better system architecture for energy harvesting and self-powered application platforms with three different interacting modes of liquid contact. Moreover, several parameters of the contact solvents such as the ionic activity and polarity have been studied to understand the practical applicability of S–L TENGs to harvest energy from different natural and artificial resources. In addition, the scope of harvesting mechanical energy from other volatile organic compounds has been studied recently. Self-powered applications of S–L TENGs in various fields have also been demonstrated by different research groups. This work indicates recent progress in the development of S–L TENGs for the first time in terms of the different properties of solid and liquid contact materials along with their respective applications. Furthermore, the work concludes with perspectives, future opportunities, and major challenges of fabricating S–L TENGs as an efficient energy harvester. References Chatterjee, S. Saha, S. R. Barman, I. Khan, Y.-P. Pao, S. Lee, D. Choi, Z.-H. Lin (2020) Nano Energy, 69, 105092.Z‐H. Lin, G. Zhu, Yu S. Zhou, Y. Yang, P. Bai, J. Chen, Z. L. Wang (2013) Angew. Chem. Int. Ed., 52, 5065-5069.Z-H. Lin, Y. Xie, Y. Yang, S. Wang, G. Zhu, Z. L. Wang (2013) ACS Nano, 7, 4554-4560.Z‐H. Lin, G. Cheng, L. Lin, S. Lee, Z. L. Wang (2013) Angew. Chem. Int. Ed., 52, 12545-12549.Z-H. Lin, G. Cheng, S. Lee, K. C Pradel, Z. L. Wang (2014) Adv. Mater., 26, 4690-4698.

A Multidirectional Pendulum Kinetic Energy Harvester Based on Homopolar Repulsion for Low-Power Sensors in New Energy Driverless Buses

There is a large amount of inertial kinetic energy wasted during the driving of new energy driverless buses. In this paper, a novel multidirectional pendulum kinetic energy harvester, based on homopolar repulsion, is designed for low-powered sensors in new-energy driverless buses. The proposed system consists of three main components: kinetic energy harvest module, energy conversion module and power storage module. The kinetic energy harvest module includes a multidirectional capture mechanism and a deformation amplification mechanism, which captures the acceleration direction of the vehicle, and harvests the inertial kinetic energy through the pendulum swinging respectively. In the energy conversion module, deformation of the piezoelectric beam generates electricity, due to homopolar repulsion from the magnets on the pendulum and piezoelectric beam. The power storage module stores electricity in supercapacitors to power the inertial measurement unit, acceleration sensor and other low-power sensors. The proposed system has completed simulation analysis and prototype tests, which show that the system featuring voltage of 13.6 V and power of 1.233 mW, illustrating the feasibility of self-powered applications in low-power sensors for new energy driverless buses. Flow chart of the proposed kinetic energy harvester

Power density improvement based on investigation of initial relative position in an electromagnetic energy harvester with self-powered applications

In this paper, we originally report a breakthrough in the power density of a novel electromagnetic energy harvester to scavenge ambient low-frequency vibration energy. The harvester adopted a configuration of alternating south- and north-pole magnet array, which causes a step-change in magnetic flux density, contributing to high electromotive force output. Through analysis of the coil configuration and the initial relative position between coils and magnets, the harvester can take full advantage of the abrupt flux density change, which enhances its output power significantly. Experimental results adequately validated the simulation analysis regarding the correlation between the initial relative position and output power, and exhibited a high output performance. Namely, the maximum average power and power density the harvester yields are 44.8 mW and 1.6 , respectively, with the optimum resistance of 30 Ω at resonance under the excitation of 1 g. It took the harvester around 5 min to charge a button lithium battery up to 21%. Meanwhile, a LED array composed of 180 diodes was successfully lighted up, and a calculator was powered for around 630 s within a 20 s of charging period. This research shows great potential in the development of self-powered systems.

MoS2/h-BN/Graphene Heterostructure and Plasmonic Effect for Self-Powering Photodetector: A Review.

A photodetector converts optical signals to detectable electrical signals. Lately, self-powered photodetectors have been widely studied because of their advantages in device miniaturization and low power consumption, which make them preferable in various applications, especially those related to green technology and flexible electronics. Since self-powered photodetectors do not have an external power supply at zero bias, it is important to ensure that the built-in potential in the device produces a sufficiently thick depletion region that efficiently sweeps the carriers across the junction, resulting in detectable electrical signals even at very low-optical power signals. Therefore, two-dimensional (2D) materials are explored as an alternative to silicon-based active regions in the photodetector. In addition, plasmonic effects coupled with self-powered photodetectors will further enhance light absorption and scattering, which contribute to the improvement of the device’s photocurrent generation. Hence, this review focuses on the employment of 2D materials such as graphene and molybdenum disulfide (MoS2) with the insertion of hexagonal boron nitride (h-BN) and plasmonic nanoparticles. All these approaches have shown performance improvement of photodetectors for self-powering applications. A comprehensive analysis encompassing 2D material characterization, theoretical and numerical modelling, device physics, fabrication and characterization of photodetectors with graphene/MoS2 and graphene/h-BN/MoS2 heterostructures with plasmonic effect is presented with potential leads to new research opportunities.

A novel wind energy harvesting system with hybrid mechanism for self-powered applications in subway tunnels

With the rapid development of urban rail transit, the safety maintenance of subway tunnels has attracted attention in various countries. Tunnel safety monitoring systems are used to ensure the safety of subway operation. This paper presents a new type of self-powered system for WSN nodes in tunnels to solve the power supply problem in subway tunnel safety monitoring systems. This new self-powered system collects wind energy in subway tunnels and converts it into electrical energy for storage and utilization. The system is composed of three parts: electromagnetic wind energy acquisition module, piezoelectric wind energy acquisition module, and power generation energy storage module. The electromagnetic wind energy acquisition module uses the principle of electromagnetic induction to convert wind energy into electrical energy. The piezoelectric wind energy acquisition module uses piezoelectric patches to convert wind energy into electrical energy. The power generation energy storage module converts the collected AC power into DC power, stores it in the supercapacitor, and supplies power to the WSN nodes. Experimental data shows that the energy output power of the system at a wind speed of 7 m/s is 59.31 mW. The Chengdu subway line 2 was selected for case study; the energy consumed by WSN nodes accounts for 49.4%–59.8% of the energy collected by the system. The proposed system can provide continuous and stable power for WSN node systems in subway tunnels.

Investigation of frequency-up conversion effect on the performance improvement of stack-based piezoelectric generators

This paper originally investigates the influence of frequency-up conversion effect on piezoelectric stack generators for high-performance energy harvesting. A compressive-mode piezoelectric generator is proposed comprised of a piezostack and a spring-mass system for electromechanical transduction and mechanical excitation, respectively. The frequency-up conversion effect is induced by amplitude truncations of the mass under external excitation. A control group, i.e. without truncation, is set for performance comparisons. Experimental results indicate that, with the frequency-up conversion, instantaneous power and average power are enhanced by over 1000 and 177 times, respectively. Each voltage response cycle consists of two stages: high-frequency high-amplitude oscillation and the rest of low-frequency low-amplitude harmonic vibration. The frequency of the former stage determines impedance matching. Due to the frequency converted up by 69 times, and intrinsic high capacitance of the stack, the matched resistance is significantly reduced from over 5 kΩ to 73.10 Ω, resulting much higher power response than that without conversion. Additionally, increase of spring stiffness causes the decrease of voltage responses and less effectiveness of frequency conversion effect. In this work we conclusively report that an instantaneous peak power output of 0.32 W can be generated from a millimeter-size piezoelectric generator, which can foster development of high-viability self-powered applications.

Wearable Nanogenerators: Working Principle and Self-Powered Biosensors Applications

Wearable self-powered sensors represent a theme of interest in the literature due to the progress in the Internet of Things and implantable devices. The integration of different materials to harvest energy from body movement or the environment to power up sensors or act as an active component of the detection of analytes is a frontier to be explored. This review describes the most relevant studies of the integration of nanogenerators in wearables based on the interaction of piezoelectric and triboelectric devices into more efficient and low-cost harvesting systems to power up batteries or to use the generated power to identify multiple analytes in self-powered sensors and biosensors.

Semiconductor-based dynamic heterojunctions as an emerging strategy for high direct-current mechanical energy harvesting

Direct-current (DC) power generation through mechanically modulated semiconductor-based heterojunctions is a newly found physical phenomenon, where mechanical-to-electric power conversion can take place in various material systems, including e.g., metal/semiconductor sliding Schottky contact, p-n junction sliding/impact contact, metal/conducting polymer compressive contact, and liquid/semiconductor moving interface. Such systems are capable of generating a continuous DC with a current density up to 10–100 A/m2, which is 3–4 orders of magnitude higher than the pulsed alternating current (AC) density in traditional piezoelectric and triboelectric nanogenerators. Unlike the dielectric displacement current generation mechanism in traditional methods, the DC generation is associated with a multi-scale and multi-physics interaction at the dynamic interfaces with semiconductor junctions involved. The resulting electronic excitation, which is referred to the tribovoltaic effect, and the subsequent direct electron conduction are considered to play a key role in the DC power output. In an effort to provide an overview of the novel concepts and inspiration for their applications, the fundamental aspects of the dynamic interfaces, nanoscale observation of the phenomenon, and recent progress in material and device development are summarized and discussed in this review. The dynamic DC generator concept shows great promise for scaled-up as well as miniaturized self-powering applications. Moreover, the new photo/thermal-electro-mechanical coupling effects discovered in the dynamic semiconductor heterojunctions may be exploited for hybrid energy harvesting and advanced sensing.

Microbial fuel cells for in-field water quality monitoring.

The need for water security pushes for the development of sensing technologies that allow online and real-time assessments and are capable of autonomous and stable long-term operation in the field. In this context, Microbial Fuel Cell (MFC) based biosensors have shown great potential due to cost-effectiveness, simplicity of operation, robustness and the possibility of self-powered applications. This review focuses on the progress of the technology in real scenarios and in-field applications and discusses the technological bottlenecks that must be overcome for its success. An overview of the most relevant findings and challenges of MFC sensors for practical implementation is provided. First, performance indicators for in-field applications, which may diverge from lab-based only studies, are defined. Progress on MFC designs for off-grid monitoring of water quality is then presented with a focus on solutions that enhance robustness and long-term stability. Finally, calibration methods and detection algorithms for applications in real scenarios are discussed.

A novel kinetic energy harvester using vibration rectification mechanism for self-powered applications in railway

Rail transit system has been considered to have a large energy harvesting potential, and to be usable to achieve self-powering for rail-attached electrical installations. Dowty retarder is a key device installed on the side of rails to assist train braking, which can be used as a carrier for kinetic energy harvesting. In this paper, a high-efficiency kinetic energy harvester (KEH) based on a railway Dowty Retarders (DRs) is investigated. This new KEH can accumulate the kinetic energy of a decelerating train using a novel vibration rectification mechanism. The current study comprises four main components: energy input module, motion transmission module, generation module, and energy storage module. The energy input module has a screw-nut mechanism that can convert linear vibration into rotational motion. As a core component of the entire device, the motion transmission module contains a special closed-loop shaped gear train that converts the two-way rotary motion into a unidirectional rotation. The final unidirectional rotation is transferred to the generation module for power generation and the generated energy is stored in the energy storage module. Finally, both experimental and simulation approaches were performed to verify the dynamics response of the KEH mechanism. The maximum efficiencies of 55.4% and 51.9% are obtained during the simulation and experimental analyses. It is validating that the KEH mechanism is promising and practical in self-powered applications for the heavy haul railway.

Energy production potential from the wake of moving traffic vehicles on a highway by the array of low economic VAWT

The amount of wind energy production by strong wakes rises from the high-speed moving vehicles. At this research to use highway moving vehicles wake energy for the generation of electrical energy through vertical axis wind turbine throughout the Bhopal to Indore as well as it is beneficial to all over India’s highway where vehicles speed is constantly high. The generated electrical energy is used for renewable self-powered applications such as lighting purposes such as traffic signals, highway lights, and light guidelines in a highway by high-speed vehicles. In this paper, a convenient renewable wind energy gathering scheme of low economic vertical axis wind turbine has been designed and fabricated using low-cost materials to provide electricity alongside the highway between Bhopal and Indore in rural zones where availability of electric power is less. This energy can be generated by using an array of vertical axis wind turbines (VAWT) located in the middle of the highways and that can deliver an essential significant amount of wind to rotate a wind turbine due to high-speed vehicles moving in both directions and the natural localized wind. This system is economically viable for the society & villages also any men easily build it.

High-Performance Al/PDMS TENG with Novel Complex Morphology of Two-Height Microneedles Array for High-Sensitivity Force-Sensor and Self-Powered Application.

Triboelectric nanogenerators (TENGs) are widely applied to self-powered devices and force sensors. TENGs consist of the electrode-layer frequently made of high-cost conductors (Ag, Au, ITO) and the tribo-layer of rigid negative-triboelectricity fluoropolymers (PTFE, FEP). The surface morpholoy is studied for enhancing performance. Here, a high-performance Al/PDMS-TENG is proposed with a complex morphology of overlapped deep two-height microneedles (OL-DTH-MN) fabricated by the integrated process of low-cost CO2 laser ablation and PDMS casting for self-powered devices and high-sensitivity force/pressure sensors. The high open-circuit voltage and short-circuit current of the OL-DTH-MN-TENG are 167 V and 129.3 µA. Also, the sensitivity of the force/pressure sensor of the OL-DTH-MN-TENG is very high, 1.03 V N-1 and about 3.11 V kPa-1 , at an area of 30 cm2 that is much higher than the sensitivity of about 0.18-0.414 V N-1 and 0.013-0.29 V kPa-1 of conventional TENG sensors. Meanwhile, the high-performance OL-DTH-MN-TENG not only exhibits the energy storage capability of charging a 0.1 µF capacitor to 2.75 V at 1.19 s, to maximum 3.22 V, but also activates various self-powered devices including lighting colorful 226 LEDs connected in series, the "2020-ME-NCKU" advertising board, a calculator and a temperature sensor. Numerical simulation is also performed to support the experiments.

Grid of hybrid nanogenerators for improving ocean wave impact energy harvesting self-powered applications

This paper describes an alternative approach for improving the output power performance for coastal wave impact energy harvesting systems, located at water-structure interfaces. This is achieved by simultaneously coupling the triboelectric and piezoelectric effects, exhibited in some materials. The use of finite element modelling, and experimental electrical characterization, enables the integration of hybrid devices into a breaking water wave generator tank. This provides a mechanism for simulating actual ocean wave conditions at low frequencies (0.7 Hz–3 Hz). Enhancements in the output performance by a factor of 2.24 and 3.21, relative to those obtained from using single triboelectric and piezoelectric nanogenerators, were achieved. This is demonstrated by evaluating the output current, voltage, transferred charge, and charging performance from a grid of up to four hybrid devices connected to capacitors of different capacitance values. Such hybrid devices were capable of powering a one-way wireless transmitter with a generated output power between 340.85 μW and 2.57 mW and sent a signal to a receiver at different distances from 2 m to 8 m. The research shows that such an integrated device can provide a promising mechanism for developing high-performance energy harvesting mechanisms for ocean wave impact to drive self-powered systems having an average power consumption of 1–100 mW. Further, it is estimated that through the construction of large water-hybrid nanogenerator-structure interfaces, output powers of approximately 21.61 W can be generated for powering networks of self-powered sensing systems in smart large-scale applications.

Simulation of β-Ga2O3 vertical Schottky diode based photodetectors revealing average hole mobility of 20 cm2 V−1 s−1

With a wide bandgap of ∼4.85 eV, high chemical and thermal stability, and melt growth availability, β-Ga2O3 has been found in a large number of solar blind photodetector (SBP) applications including missile guidance, flame detection, water purification, and intersatellite communication. The modelling of a Schottky diode (SD) based SBPs is crucial in order to reach high external quantum efficiency (EQE), especially for self-powered applications and also to extract hole mobility in these devices. The EQE performance of β-Ga2O3 vertical SD SBPs with various Schottky contact finger spacings is obtained using highly controversial hole mobility values reported in the literature. By modelling experimentally demonstrated EQE values of the existing β-Ga2O3 vertical SD SBPs, average nonequilibrium hole mobility value of ∼20 cm2 V−1 s−1 is extracted, which is quite higher than the claimed theoretical value of 1 × 10−6 cm2 V−1 s−1 and motivates for the efforts of technologically important p-type β-Ga2O3. By modelling the efficiency of full Schottky metal covered vertical SD SBPs by using hole mobility value of 20 cm2 V−1 s−1, internal quantum efficiency of 92% is obtained at an optimum n-type doping concentration of 1 × 1016 cm−3.

Enhanced mechanical energy harvesting capability in sodium bismuth titanate based lead-free piezoelectric

The demand for high-performance lead-free piezoelectric materials towards mechanical energy harvesting has been driven by the continuous requirements of self-powered applications such as wireless sensor network systems and biomedical devices, etc. Herein, manganese-doped sodium bismuth titanate based lead-free ternary piezoelectric system 0.92(Na0.5Bi0.5)TiO3-0.04(K0.5Bi0.5)TiO3-0.04BaTiO3 (NBT-KBT-BT) was developed and the critical role of manganese on tailoring the microstructure and electrical properties was investigated. The highest piezoelectric coefficient (d33) of 140 pC/N with figure of merit (d33 × g33) of 1790 × 10−15 m2/N has been achieved. Both high open-circuit voltage of ∼12.2 V and power density of ∼0.37 μW/mm3 were obtained based on cantilever-type energy harvester. This work provides a promising paradigm for the development of high-performance mechanical energy harvesting devices by tailoring the composition of lead-free piezoelectric ceramics.