Self-powered Energy Harvesting Research Articles

Dissolvable photovoltaic cells on hydrogel

Solar energy is potentially the largest source of renewable energy for providing electrical power for human society. However, significant advances are required to make photovoltaic technologies have a low-carbon footprint in manufacture, be environmentally friendly at the end of their lives through recyclability, and be biodegradable. Here we report dissolvable organic photovoltaic devices based on poly(2-hydroxyethyl methacrylate), which show equal power conversion efficiency to their glass substrate-based counterparts. We use a novel method of including smectic liquid crystal (7-dioctyl[1]benzothieno[3,2- b][1]benzothiophene, C8-BTBT) as a crystal phase regulator in the heterojunction donor:acceptor polymer system to maintain the disposable organic solar cell efficiency without pre- or post-thermal annealing. The results show strong promise not only for more sustainable solar-cell fabrication but also as disposable and biocompatible solar cells for self-powered (energy harvesting) wearable and biomedical devices.

A compact self-powered inductor-less piezoelectric energy harvesting circuit using gyrator

In traditional low-frequency energy harvesting circuits, a large matched inductor with a large size is unavoidable. To reduce the size of the circuit, this paper proposes a compact self-powered inductor-less high-efficiency piezoelectric energy harvesting circuit using a low-power-consumption gyrator. A self-powered floating gyrator inductor is used in place of an inductor in the proposed circuit, and the required phasor response is acquired by using its voltage–current (V–I) relationship. The proposed circuit offers easy adjustability and performance benefits in small integrated circuits packages. The proposed circuit can be cost-effective and provide reduced area advantages in autonomous self-powered Internet-of-Things and wireless sensor nodes applications. Regarding harvested energy, the proposed circuit with a storage capacitor of 0.24 F can obtain 320% improved performance than standard energy harvesting along with the lowest power consumption of 0.25 µW in self-powered operation. The proposed technique can also be applied to similar piezoelectric energy harvesting strategies with large inductors.

Self-powered multi-PZTs energy harvesting interface based on extensible PSSHI rectification with power region optimization technique

Self-powered multi-PZTs energy harvesting interface based on extensible PSSHI rectification with power region optimization technique

Self-powered piezoelectric energy harvesting with ultra-low power consumption for low-amplitude ambient vibrations

Self-powered piezoelectric energy harvesting with ultra-low power consumption for low-amplitude ambient vibrations

The nexus of sustainable fisheries: A hybrid self-powered and self-sensing wave energy harvester

Wave energy harvesters (WEHs) are an effective solution to the problem of powering sensors in marine fisheries. A future direction for WEHs is to achieve wave monitoring while meeting the power requirements of the sensors. This paper presents a hybrid self-powered and self-sensing wave energy harvester (HSS-WEH), which consists of three modules: an energy input module, a self-powered module, and a self-sensing module. In this study, an eccentric pendulum is used to capture low-frequency irregular wave energy. The proposed rectification enhancement mechanism (REM) converts the bidirectional rotation of the spindle into the unidirectional rotation of the magnet flywheel. In addition, a triboelectric nanogenerator based on rolling PTFE balls is used to convert wave information into electrical signals for wave monitoring. The optimization of the mass of the eccentric pendulum was achieved through a six-degree-of-freedom platform experiment. At 0.3 Hz, the electromagnetic generator power with REM is enhanced by 36.11 % to 7.84 mW than without REM. Furthermore, the self-sensing module achieves a high level of accuracy, reaching 98.62 % in identifying the risk level of the waves. Water tank experiments and energy consumption analysis of sensors confirm the practical applicability of HSS-WEH in sustainable fisheries.

A self-powered and self-sensing knee negative energy harvester

Wearable devices realize health monitoring, information transmission, etc. In this study, the human-friendliness, adaptability, reliability, and economy (HARE) principle for designing human energy harvesters is first proposed and then a biomechanical energy harvester (BMEH) is proposed to recover the knee negative energy to generate electricity. The proposed BMEH is mounted on the waist of the human body and connected to the ankles by ropes for driving. Double-rotor mechanism and half-wave rectification mechanism design effectively improves energy conversion efficiency with higher power output density for more stable power output. The experimental results demonstrate that the double-rotor mechanism increases the output power of the BMEH by 70% compared to the single magnet-rotor mechanism. And the output power density of BMEH reaches 0.07 W/kg at a speed of 7km/h. Furthermore, the BMEH demonstrates the excitation mode detection accuracy of 99.8% based on the Gate Recurrent Unit deep learning model with optimal parameters.

Janus CoMOF-SEBS Membrane for Bifunctional Dielectric Layer in Triboelectric Nanogenerators.

Considerable research has been conducted on the application of functional nano-fillers to enhance the power generation capabilities of triboelectric nanogenerators (TENGs). However, these additives often exhibit a decrease in output power at higher concentration. Here, a Janus cobalt metal-organic framework-SEBS (JCMS) membrane is reported as a dual-purpose dielectric layer capable of efficiently capturing and blocking charges for high-performance TENGs. The JCMS is produced asymmetrically through gravitational sedimentation, employing spherical CoMOFs within a diluted SEBS solution. Beyond its dual dielectric characteristics, the JCMS showcases exceptional mechanical durability, displaying notable stretchability of up to 475% and remarkable resilience when subjected to diverse mechanical pressures. Consequently, the JCMS-TENG produces a maximum peak-to-peak voltage of 936V, a current of 42.8µA, and a power density of 10.89Wm- 2 when exposed to an external force of 10N at a 5Hz frequency. This investigation highlights the potential of JCMS-TENGs with unique structures, known for their exceptional energy harvesting capabilities, mechanical strength, and flexibility. Additionally, the promising prospects of easily produced asymmetric structures is emphasized with bifunctionalities for developing efficient and flexible MOFs-based TENGs. These advancements are well-suited for self-powered wearables, rehabilitation devices, and energy harvesters.

Textured nanofibers inspired by nature for harvesting biomechanical energy and sensing biophysiological signals

Flexible electronics are emerging as a promising new platform for wearables; however, their practical utility is hindered by the limited battery life of electronic devices and the need for frequent battery replacements. Here, we report self-powered, flexible, permeable, tough, and lightweight biomechanical energy harvesting and biophysiological sensing devices using textured nanofibers for wearable electronics applications. The textured structure draws inspiration from two major sources of nature: the interior porous structure of jute fibers and the rough bark texture of trees. Interior pores are introduced to the nanofibers to increase compressibility and breathability like jute fibers. The inspiration from the rough bark texture also leads to a wrinkled surface morphology of the nanofibers to expand the surface area and consequently enhance toughness. To design and fabricate such a textured structure, the vapor-induced phase separation mechanism and electrospinning technique are employed within a controllable high humidity environment. Consequently, the textured nanofiber-based devices exhibit a well-rounded performance in electrical, mechanical, and physical properties, specifically demonstrating a significantly enhanced piezoelectric performance with more than two-fold electrical generation. These textured devices not only effectively harvest biomechanical energy from human movement but also demonstrate sensing capability for self-powered multifunctional biophysiological monitoring applications by leveraging the same piezoelectric mechanism. The novel design strategy for the textured nanofibers and their resultant balanced performance promotes the versatility and practical applicability of piezoelectric fibrous energy harvesting and sensing devices, contributing to the development of next-generation flexible and wearable electronics.

Highly positive fluorophlogopite for enhanced power generation in triboelectric nanogenerators prepared on a flexible Ni–Cu fabric

Recent developments in triboelectric nanogenerators (TENGs) facilitate creation of sustainable, self-powered energy harvesting systems. In our study, we introduce fluorophlogopite as a positive triboelectric material with excellent electron transfer capabilities. We investigate the efficacy of a fluorophlogopite-based TENG, MgF-mica-TENG. We use a simple spray method on flexible Ni–Cu conductive fabric platforms to perform electrical analyses including open-circuit voltage (Voc), short circuit current (Isc), and peak power density using a home-made, 3D-printed, M-shaped spring setup. MgF-mica-TENG exhibited enhanced performance compared to the conventional muscovite-based TENG (Al-mica-TENG). This enhanced performance is primarily attributed to the increased surface potential of fluorophlogopite, which facilitate efficient charge transfer upon the contact of two electrodes, combined with optimized 11fabrication parameters. Based on our findings, we anticipate that MgF-mica materials can pave the way to the development of a comprehensive strategy to powering smart electronics, harnessing the abundant mechanical energy sources found in our daily surroundings.

Enhancing Triboelectric Nanogenerator Performance with Metal–Organic-Framework-Modified ZnO Nanosheets for Self-Powered Electronic Devices and Energy Harvesting

Enhancing Triboelectric Nanogenerator Performance with Metal–Organic-Framework-Modified ZnO Nanosheets for Self-Powered Electronic Devices and Energy Harvesting

Polyvinyl alcohol-based economical triboelectric nanogenerator for self-powered energy harvesting applications

Triboelectric nanogenerators (TENGs) have emerged as a promising alternative for powering small-scale electronics without relying on traditional power sources, and play an important role in the development of the internet of things (IoTs). Herein, a low-cost, flexible polyvinyl alcohol (PVA)-based TENG (PVA-TENG) is reported to harvest low-frequency mechanical vibrations and convert them into electricity. PVA thin film is prepared by a simple solution casting technique and utilized to serve as the tribopositive material, polypropylene film as tribonegative, and aluminum foil as electrodes of the device. The dielectric-dielectric model is implemented with an arch structure for the effective working of the PVA-TENG. The device showed promising electrical output by generating significant open-circuit voltage, short-circuit current, and power . Also, PVA-TENG is subjected to a stability test by operating the device continuously for 5000 cycles. The result shows that, the device is mechanically durable and electrically stable. Further, the as-fabricated PVA-TENG is demonstrated to show feasible applications, such as charging two commercial capacitors with capacitances 1.1 and 4.7 μF and powering green light-emitting diodes. The stored energy in the 4.7 μF capacitor is utilized to power a digital watch and humidity and temperature sensor without the aid of an external battery. Thus, the PVA-TENG facilitates ease of fabrication, robustness, and cost-effective strategy in the field of energy harvesting for powering lower-grid electronics by demonstrating their potential as a sustainable energy source.

Dysprosium tungstate incorporated on exfoliated layered molybdenum disulfide-based a flexible and wearable piezoelectric nanogenerator for the dual purpose of self-powered energy harvesting and a smart mask for human breath monitoring

The rapid spread of the novel coronavirus (COVID-19), including the Omicron, and Delta variants, has resulted in severe economic losses and health issues worldwide. This crisis has particularly impacted the human respiratory system, demanding urgent solutions. With this goal in mind, we have developed a novel DyW@MoS2-based FPENG for self-powered energy harvesting and a smart mask for monitoring human breath. The highest piezoelectric response was observed at 30 wt% of FPENG (∼1.30 V), which is ∼1.9 times better than MoS2–PDMS FPENG. The generated voltages from the FPENG are used to charge capacitors, power the LEDs, and run a wristwatch. Additionally, the RS-FPENG is employed in real-time demonstrations as a self-powered smart mask for monitoring human breath. RS-FPENG showed ∼141 mV even ∼90% humidity, confirming that the water vapor generated doesn’t affect human breath monitoring. FFT results revealed that the RS-FPENG can distinguish between normal and fast breathing. By connecting the RS-FPENG to an LED circuit system, the glowing LED can be turned off when a person stops breathing. The fabricated smart mask exhibits excellent unique capabilities, including small size, simple fabrication, easy installation, and cost-effectiveness, making it suitable for respiratory system monitoring during the COVID-19 pandemic.

Superior piezoelectric performance of chemically synthesized transition metal dichalcogenide heterostructures for self-powered flexible piezoelectric nanogenerator

In addition to the superior electrical and optoelectronic attributes, ultrathin two-dimensional transition metal dichalcogenides (TMDCs) have evoked appreciable attention for their piezoelectric properties. In this study, we report, the piezoelectric characteristics of large area, chemically exfoliated TMDCs and their heterostructures for the first time, as verified by piezoelectric force microscopy measurements. Piezoelectric output voltage response of the MoS2-WSe2 heterostructure piezoelectric nanogenerator (PENG) is enhanced by ∼47.5% if compared with WSe2 and ∼29% if compared to MoS2 PENG, attributed to large band offset induced by heterojunction formation. This allows the scalable fabrication of self-powered energy harvesting PENGs, which can overcome the various shortcomings of complicated synthesis processes, complex fabrication steps, low yield, and poor stability. The fabricated flexible, self-powered MoS2-WSe2 heterostructure nanogenerator exhibits piezoelectric output ∼46 mV under a strain of ∼0.66% yielding a power output ∼12.3 nW, which offers better performance than other two-dimensional material based piezoelectric devices and also reveals the ability of bio-mechanical energy harvesting. This cost effective approach to fabricate eco-friendly MoS 2 -WSe 2 based fatigue free, superior performance piezoelectric-nanogenerators can be utilized to evolve flexible energy harvesting devices and may also be attractive as a self-powered, smart wearable sensor devices.

Flexible magnetoelectric PVDF–CoFe2O4 fiber films for self-powered energy harvesters

Integrating the concept of magnetoelectric in the mechanical energy harvesters through the magneto-mechano-electrical (MME) nanogenerators has been explored to realize the self-powered devices. The magnetoelectric interaction enabled the output performance of the MME nanogenerator under magnetic stimulus of the active components of the energy harvesters. In this perspective, we fabricated a flexible biomechanical and MME nanogenerator using PVDF/CoFe2O4 fibers composite films. CoFe2O4 fibers were synthesized by the electrospinning technique and the process parameters were optimized to achieve uniform and bead-free fibers. The structural and morphological properties were investigated through scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM). The structural and morphology revealed the fibers calcined at 800 °C with a heating rate of 2 °C/min produced bead-free continuous fibers with a fiber diameter of 210 nm with cubic spinel crystalline structure with a crystallite size of 34 nm. These highly crystalline fibers were used to fabricate PVDF/CoFe2O4 fibers composite films. The magnetoelectric behaviour of the films verified through polarization vs. electric field (P-E) loops under magnetic field. The leakage current density and mechanism of the composite films were investigated, and it was discovered that the mechanism was due to Schottky emission. Further the energy harvesting performance of the composite films were estimated where the nanogenerator achieved an output voltage of 13 V under biomechanical tapping force while the MME nanogenerator produced 3.5 V under a low frequency stray magnetic field of 6 Oe with a power density of 28 μW/m2.

Omnidirectional Energy Harvesting Fleeces.

Underwater mechanical energy harvesters are of rising interest due to their potential for various applications, such as self-powered ocean energy harvesters, monitoring devices, and wave sensors. Pressure-responsive films and stretch-responsive fibers, which provide high electrical power in electrolytes and have simple structures that do not require packing systems, are promising as harvesters in the ocean environment. One drawback of underwater mechanical energy harvesters is that they are highly dependent on the direction of receiving external forces, which is unfavorable in environments where the direction of the supplied force is constantly changing. Here, we report spherical fleece, consisting of wool fibers and single-walled carbon nanotubes (SWCNTs), which exhibit repetitive electrical currents in all directions. No matter which direction the fleece is deformed, it changes the surface area available for ions to access SWCNTs electrochemically, causing a piezoionic phenomenon. The current per input mechanical stress of the fabricated SWCNT/wool energy harvester is up to 33.476 mA/MPa, which is the highest among underwater mechanical energy harvesters reported to date. In particular, it is suitable for low-frequency (<1 Hz) environments, making it ideal for utilizing natural forces such as wind and waves as harvesting sources. The operating mechanism in the nanoscale region of the proposed fleece harvester has been theoretically elucidated through all-atom molecular dynamics simulations.

Energy harvesting using two-dimensional magnesiochromite (MgCr2O4)

Two-dimensional (2D) materials with high surface activity can be utilized for harvesting energy from small mechanical sources using flexoelectricity. In the present work, we have synthesized an atomically thin 2D spinel MgCr2O4 by a liquid-phase exfoliation process, and characterization shows the preferential exfoliation along the (111) plane with low formation energy. The fabricated flexoelectric device produces an electrical response up to ∼3 V (peak-to-peak voltage) upon pressing and releasing the cell with ∼0.98 N force. Furthermore, the energy harvesting properties of 2D MgCr2O4 are explored by combining bending with other sources of external energy, with applied varying magnetic flux (Vmax = ∼2.6 V) and temperature with 0.9 N force (Vmax = ∼18 V). Our calculations determine that 2D MgCr2O4 has a flexoelectric coefficient of approximately μXZXZ = 0.005 nC/m. Overall, the results indicate that 2D MgCr2O4 is a very promising material for the next generation of self-powered wearable electronics and energy harvesting.

Self-powered energy harvesting and implantable storage system based on hydrogel-enabled all-solid-state supercapacitor and triboelectric nanogenerator

The development of personalized and wearable devices has accelerated the investigation of flexible, biocompatible, and stretchable supercapacitors (SCs), enabling the integration into all-in-one integrated self-charging power packages. However, the most explored polyvinyl alcohol (PVA)-based gel electrolytes cannot well meet the requirements of stretchable and biocompatible SCs, mainly due to their inherently poor stretchable features. Herein, we report a new MXene-based polyacrylamide (PAM) hydrogel with high mechanical stretchability and excellent ionic conductivity. The hydrogel is utilized as the electrolyte of SCs and the electrode of self-powered triboelectric nanogenerator (TENG) simultaneously in the integrated self-charging power package. The SC exhibits good biocompatibility, high capacitance, high flexibility, and long-term stability, which is suitable for wearable energy storage devices and implanted electronic device. It can be implanted into rats with high biocompatibility. It has promising for use in portable, wearable, and implantable energy related devices.

Large-scale production of the 3D warp knitted terry fabric triboelectric nanogenerators for motion monitoring and energy harvesting

In the coming era of intelligence, the textile-based triboelectric nanogenerator (T-TENG) is considered to be one of the most important development directions to achieve flexible wearable sensing and micro/nano energy harvesting. Among them, due to excellent physical proeprties of nano/micro fibrous structure, fluff/terry /fleece/brush/fur/pile/villus/velvet structure fabrics are gradually being applied to TENG. However, the research on the relationship between the triboelectric properties of TENG and the structural parameters of fluff, as well as the fabrication of large-scale fluff TENG are very lacking. Here, a 3D warp knitted terry fabric TENG (WKTF-TENG) is mass produced by a mature warp knitted technology. The triboelectric properties of contact-separation mode, lateral-sliding mode and single electrode mode are systematically investigated by changing the height and density of the pile loops of the fabric. This study demonstrates that terry fabric is an excellent triboelectric materials for it high output and good wear resistance, especially for ateral-sliding mode. The output of WKTF-TENG even increases with the increase of working cycles due to the more fluffy and uniform distribution of fibers on the surface of the fabric. What’s more, the triboelectric properties of terry fabrics also have a great relationship with the compression properties of the pile loops. As smart textile matertail, WKTF-TENG can be usde as self-powered motion monitoring sensor and energy harvesting device. The research on the output performance of WKTF-TENG through theoretical analysis and experimental testing may provides a promising direction for fluff fabric based TENG.

Salts induced piezoelectric effect in electrospun PVDF based nanohybrids for efficient energy harvesting

Polymer-based nanofibers have been pioneering materials for energy harvesting applications. Addition of nanoparticles or salts induce a polar phase to the materials, which enhances the applicability of the material. Salts based PVDF nanofibers have been prepared through an electrospinning process for energy harvesting applications. Incorporation of the metal-salts to the PVDF matrix leads to a better electrostatic interaction which results in better quality beadless fibers. The changes in the structural and thermal properties suggest the transformation of the non-polar phase to an electroactive phase. The increase in the content of the piezo-active phase with the addition of the metal-salts (93%) as compared to pristine PVDF (74%) provides a path for the prepared material to be used in piezoelectric energy harvesting applications. The device fabricated from the electrospun scaffold was subjected to external stress to examine the efficacy of the prepared material. The maximum output voltage generated from finger tapping for P-Li is around 42 V which is much higher as compared to that for the pristine PVDF nanofiber (19.8 V). The piezoelectric coefficient (d33) and maximum output current obtained for the Li-based PVDF nanohybrid are around 27 pC/N and 2.7 μA, respectively, which are considerably higher than the corresponding values for the PVDF fibers (6 pC/N and 0.07 μA). The charging–discharging capability of the prepared device and the electromechanical responses against different modes of external stress application provide further evidence for the prepared hybrid material to act as a potential self-powered piezoelectric energy harvester.

Experimental Demonstration of STT-MRAM-based Nonvolatile Instantly On/Off System for IoT Applications: Case Studies

Energy consumption has been a big challenge for electronic devices, particularly for battery-powered Internet of Things (IoT) equipment. To address such a challenge, on the one hand, low-power electronic design methodologies and novel power management techniques have been proposed, such as nonvolatile memories and instantly on/off systems; on the other hand, the energy harvesting technology by collecting signals from human activity or the environment has attracted widespread attention in the IoT area. However, the system with self-powered energy harvesting may suffer frequent energy failures or fluctuating energy conditions, which degrade system reliability and user experience. Therefore, how to make the system under unreliable power inputs operate correctly and efficiently is one of the most critical issues for energy harvesting technology. In this article, we built an instantly on/off system based on nonvolatile STT-MRAM for IoT applications, which can instantly power on/off under different conditions of the harvested energy. The system powers on and operates normally when the harvested energy is enough (over the preset threshold); otherwise, the system powers off and stores the operational data back to the nonvolatile STT-MRAM. We described implementations of the hardware/software co-designed architecture (with image acquisition as an example) based on the commercialized 32 MB STT-MRAM, and we experimentally demonstrated the system functionality and efficiency under five typical energy harvesting scenarios, including radio frequency, thermal, solar, piezoelectric, and WIFI. Our experimental results show that the power consumption and data restore time were reduced by 15.1% and 714 times, respectively, in comparison with the DRAM-based counterpart.