Instantaneous Peak Power Research Articles

Triboelectric-electromagnetic hybrid wind energy harvesting and multifunctional sensing device for self-powered smart agricultural monitoring

The power supply for numerous small electronic sensors, which are extensively used in agricultural settings, is a critical challenge for advancing the Agricultural Internet of Things (IoT) and fostering the development of smart agriculture in the upcoming era of intelligent technology. Hereby, a triboelectric-electromagnetic hybrid wind energy harvesting and sensing device (TEH-WSD) based on triboelectric-electromagnetic hybrid generator (TEHG) and multi-channel triboelectric nanogenerator (MC-TENG) for wind direction and speed sensing is proposed. Among them, the TEHG is used to collect wind energy. The instantaneous peak power of TENG units and EMG unit in TEHG can reach 5.95 mW and 5.65 mW respectively. In addition, the modified TEHG can measure the wind speed within the range of 3–5 m/s, and the output signal of MC-TEHG can be used to measure the wind direction based on the corresponding circuit and designed program continuously. Overall, TEH-WSD is capable of detection for the wind direction, wind speed, temperature and humidity information in the environment and this work provides a solution for wind energy collection and self-powered environmental monitoring in agricultural environment.

A droplet-based electricity generator with high instantaneous power density, high efficiency, and reliable long-term stability

Droplet-based electricity generators (DEGs) have recently revolutionized the prospects for energy harvesting from raindrops. However, achieving high instantaneous power density, high efficiency, and reliable long-term stability remains challenging. Here, we propose a DEG with an intermediate metal electrode underneath the dielectric layer (IM-DEG) for substantial instantaneous outputs, high efficiency, and improved long-term stability. This intermediate metal layer not only plays a vital role as additional charge storage but also opens up a new route to inject negative charges into the dielectric layer from below to further increase the surface charge density. Unlike other ion injection techniques that inject negative charges from the top of the dielectric materials, in our case, the negative charges injected from below tend to remain in the dielectric layer without leaking to the upper electrode or droplets, resulting in elevated electrical performance and improved long-term stability. The IM-DEG's instantaneous peak voltage, power density, and energy conversion efficiency reach 836 V, 6.92 kW/m2, and 32.69%, respectively, while the instantaneous peak voltage drops less than 3% after 1000 h of a continuous flow of droplets. This method offers substantial electrical outputs with high efficiency and reliable long-term stability, paving the way for the future of raindrop energy harvesting.

Wind-driven suspended triboelectric-electromagnetic hybrid generator with vibration elimination for environmental monitoring in the high-voltage power transmission line

The sustainable development of the high-voltage power transmission system puts forward more significant requirements IoT sensor network. Currently, a large number of the IoT sensors are installed on the high-voltage transmission lines, and environmental wind energy harvesting around the outdoor power transmission lines enables a promising and feasible solution to supply distributed sensors. However, the traditional floor-mounted wind energy nanogenerator with high requirements for placement and fixation is no longer applicable to the suspension scenario of the high-voltage power transmission lines. In this work, a wind-driven suspended triboelectric-electromagnetic hybrid generator (WS-TEHG) is designed as a suspended wind cup with a three-layered integrated structure, which can be integrated with the damping structure that hanged and installed on the power transmission line, demonstrating the simultaneously achieving high efficiency wind energy harvesting and the operation stability of the device. After the structural and material optimization, WS-TEHG can achieve efficient energy collection under wide-range of the wind speed from 2.6 to 17.3 m s−1, whose TENG and EMG produced instantaneous peak power from 0.2 to 7.9 mW and 0.6–85.1 mW, respectively. Moreover, a standardized power management based on LTC 3588-based double-channel circuit was established to co-manage the outputs of the two generating modules in the hybrid generator and enhance the continuous stability of the standardized voltage output, demonstrating a shorter undervoltage charge accumulation, a faster start-up process, a lower power consumption compared with the traditional power management. Finally, a self-powered environmental monitoring system by a WS-TEHG equipped with a standardized power management circuit was developed to provide the weather and climate information around the power transmission lines, thereby demonstrating a potential and feasible for large-scale self-powered application in the field of the high-voltage power transmission lines.

Optimized performance of self-driven piezoelectric sensors through KNN/Nb2CTx synergistic effect

Flexible high-performance piezoelectric nanogenerator (PENG) excel in converting mechanical energy into electrical energy and exhibit remarkable sensitivity, a feature that is paramount for the development of self-driven piezoelectric sensors. In this study, electrospinning technology was used to prepare poly (vinylidene fluoride-co-trifluoroethylene) [P(VDF-TrFE)] based piezoelectric nanofiber composite films containing potassium-sodium niobate nano particles (KNN NPs) and Nb2CTx co-doping, as well as single-component doping. The co-doped composite film attained an optimal β-phase content of 91.33%. Owing to the enhanced dipole alignment and interface charge polarization, the piezoelectric performance of the co-doped composite film was significantly enhanced compared to that of single-component doping. The co-doped piezoelectric composite film displayed a stable maximum output voltage of 20 V and an output current of 1.46 μA. The peak instantaneous power output was measured at 9.9 μW under the optimal resistive load of 10 MΩ. Durability testing over 2000 cycles affirmed the excellent mechanical stability of the piezoelectric composite film. Moreover, the fabricated piezoelectric composite film showed considerable potential in applications such as monitoring human activities and serving as an early warning system for natural disasters such as landslides, as indicated by the test results.

Investigation of Power Density Amplification in Stacked Triboelectric Nanogenerators

In engineering practice, the output performance of contact separation TENGs (CS‐TENGs) increases with the increase of tribo‐pair area, which includes increasing the size of single layer CS‐TENGs (SCS‐TENGs) or the number of units (zigzag TENGs). However, such two strategies show significant differences in output power and power density. In this study, to seek a universal CS‐TENG design solution, the output performance of a SCS‐TENG and a zigzag TENG (Z‐TENG) is systematically compared, including voltage, current, transferred charge, instantaneous power density, and charging power density. The relationship between contact area and output voltages is explored, and the output voltage equation is fitted. The experimental results reveal that SCS‐TENGs yield better performance than Z‐TENGs in terms of voltage, power, and power density under the same total contact area. Z‐TENGs show energy loss during the transfer of mechanical energy, and such loss is aggravated by the increasing number of units. The instantaneous peak power of the SCS‐TENG is up to 22 times that of the Z‐TENG (45 cm2). Furthermore, the power density of capacitor charging of SCS‐TENGs is 131% of that of Z‐TENGs, which are relatively close. Z‐TENG is a feasible alternative when the working space is limited.

Hand-held rolling magnetic-spring energy harvester: Design, analysis, and experimental verification

Aiming at the random and low-frequency characteristics of human motion, a hand-held rolling magnetic-spring energy harvester is proposed to scavenge energy from handshaking. The harvester applies the rolling movement of a magnetically suspended magnet and possesses the merit of low damping. The dynamic model is established and the open-circuit voltages are predicted by combining Faraday's law of electromagnetic induction and finite element analysis. By calculating magnetic flux through coils, the effect of the coil’s position on energy harvesting efficiency is studied through numerical and experimental approaches. Experimental results under harmonic excitations indicate that the coil positioned directly below the stable equilibrium position of the moving magnet has the best output capability, and a maximum open-circuit voltage of 1.33 V and a half-power bandwidth of 1.61 Hz is achieved at 0.3 g. Under handshaking excitation, an instantaneous peak power of 20.15 mW is achieved, along with a maximum average power of 2.22 mW. The corresponding volume and mass power densities are respectively 26.04 μW/cm3 and 23.28 μW/g. Furthermore, handshaking excitation in 5 s to charge a capacitor of 470 μF could enable the watch, time display, timer, and hygrothermograph to operate for 1100 s, 513 s, 86 s, and 35 s respectively, demonstrating the brilliant application foreground of the proposed harvester.

A bubble energy generator featuring lubricant-impregnated surface with high durability and efficiency

Harvesting bubble energy emerges as a potential sustainable solution to harness tremendous marine energy sources. Yet, current bubble energy generators are susceptible to unstable performance owing to the degradation of the physiochemical properties of surface materials under the harsh underwater environment such as surface fouling and wetting transition. Here, we report the design of bubble energy generators featuring the cooperative integration of a slippery lubricant-impregnated porous surface and transistor-inspired architecture, referred to as SLIPS-TBG, that can generate electricity from moving bubbles with high stability in submerged conditions. In this design, the slippery and configurable lubricant layer serves as not only a smooth and mechanically stable surface for bubble transport but also a protective layer preventing the underlying solid materials from direct contact with the external harsh environment. Together with the transistor-inspired architecture, the SLIPS-TBG can deliver a stable electric output of 26.4 V, an instantaneous peak power density of 58.6 W m-3 from continuous bubble impingement in water media, even in extreme conditions involving mechanical abrasion and corrosion. We envision such a design represents a significant step toward real-life applications for bubble-based energy harvesting.

Self-Powered and Self-Sensing Blue Carbon Ecosystems by Hybrid Fur Triboelectric Nanogenerators (F-TENG)

Seaweeds are critical in the blue carbon ecosystem; however, light limitation is a bottleneck for seaweed farming, especially in turbid waters. Utilizing triboelectric generators (TENG) to provide light for seaweeds is a promising solution for enhancing seaweed growth and increasing their carbon sequestration rate. Here, we develop the hybrid fur TENG (F-TENG) designed with the fur-brush TENG (FB-TENG) and fur-sphere TENG (FS-TENG) to enhance the growth of seaweeds and achieve the self-powered and self-sensing blue carbon ecosystems. The FB-TENG exhibits a multistage step signal response, enabling the determination of the fur brush's relative displacement, which, in turn, reflects the impact of marine flow on the device in the vertical direction. The FS-TENG is employed for marine flow energy harvesting in the horizontal direction to illuminate LED lights and stimulate seaweed growth. The FS-TENG with four power generation units achieves the peak current, transferred charge, and instantaneous output power values of 29.9 μA, 0.66 μC, and 89.3mW, respectively. The seaweed cultivation experiments are conducted to demonstrate the significantly enhanced performance of the self-powered and self-sensing blue carbon ecosystems with respect to the growth of the juvenile seaweed by using the hybrid F-TENG as a self-powered light supply. A remarkable increase is observed in both the average net biomass accumulation and linear growth rate, reaching up to 10.83 ± 0.16% day-1 and 9.12 ± 0.68% day-1, respectively. Eventually, experiments are conducted in a circulating water tank to showcase the remarkable energy harvesting capabilities of the hybrid F-TENG. The reported hybrid F-TENG provides a promising solution for establishing self-powered and self-sensing blue carbon ecosystems.

Evidence for multi-scale power amplification in skeletal muscle.

Many animals use a combination of skeletal muscle and elastic structures to amplify power output for fast motions. Among vertebrates, tendons in series with skeletal muscle are often implicated as the primary power-amplifying spring, but muscles contain elastic structures at all levels of organization, from the muscle-tendon to the extracellular matrix to elastic proteins within sarcomeres. The present study uses ex vivo muscle preparations in combination with high-speed video to quantify power output, as the product of force and velocity, at several levels of muscle organization to determine where power amplification occurs. Dynamic ramp-shortening contractions in isolated frog flexor digitorum superficialis brevis were compared with isotonic power output to identify power amplification within muscle fibers, the muscle belly, free tendon, and elements external to the muscle-tendon. Energy accounting revealed that artifact from compliant structures outside of the muscle-tendon unit contributed significant peak instantaneous power. This compliance included deflection of clamped bone that stored and released energy contributing 195.22±33.19 W kg-1±s.e.m. to the peak power output. In addition, we find that power detected from within the muscle fascicles for dynamic shortening ramps was 338.78±16.03 W kg-1±s.e.m., or nearly twice the maximum isotonic power output of 195.23±8.82 W kg-1±s.e.m. Measurements of muscle belly and muscle-tendon unit also demonstrated significant power amplification. These data suggest that intramuscular tissues, as well as bone, have the capacity to store and release energy to amplify whole-muscle power output.

Gas discharge tubes for significantly boosting the instantaneous current and active power of load driven by triboelectric nanogenerators

Based on impedance matching of the power management circuit (PMC) with a switch, the instantaneous peak power of triboelectric nanogenerators (TENGs) is significantly improved, recently. However, a high output power of TENGs does not generally mean a high active power consumed by the load, that is low energy utilization efficiency. Here, leveraging plasma discharge, we propose an effective approach by means of a gas discharge tube (GDT), as a rapid switch of a millisecond, resulting in boosting over 4000 times of peak current up to 170.7 mA at a low resistance of 5 Ω. When the TENG runs at 20 Hz, the pulse current occurs every 571.4 ms, and the active peak power also increases to 165.5 mW. With such a high-power output, a 16 W light group can be lit wirelessly even when blocked by a human hand. As commercial discrete components, the GDTs are available in a variety of models, providing a new, cheap, and directly exploitable peak gain option. Similar to diodes, capacitors, and resistors, we are firmly convinced that GDTs will be widely utilized in PMC for TENG.

Leaf‐Like TENGs for Harvesting Gentle Wind Energy at An Air Velocity as Low as 0.2 m s−1

AbstractExisting technologies for harvesting electrical energy from gentle wind face an enormous challenge due to the limitations of cut‐in and rated wind speed. Here, a leaf‐like triboelectric nanogenerator (LL‐TENG) is proposed that uses contact electrification caused by the damped forced vibration of topology‐optimized structure consisting of flexible leaf, vein bearing plate, and counterweight piece. The effectiveness of the topology‐optimized leaf‐like structure is studied, which solves the problem of reduced output due to electrostatic adsorption between the leaf surfaces while reducing the cut‐in (0.2 m s−1) and rated wind speed (2.5 m s−1). The LL‐TENG unit having small dimensions of 40 cm−2 (mass of 9.7 g) at a gentle wind of 2.5 m s−1 exhibits outstanding electrical performances, which produces an open‐circuit voltage of 338 V, a short‐circuit current of 7.9 µA and the transferred charge density of 62.5 µC m−2 with a low resonant frequency of 4 Hz, giving an instantaneous peak power of 2 mW. A distributed power source consists of the five LL‐TENGs in parallel is developed by designed self‐adaptive structure, for which the peak power output reaches 3.98 mW, and its practicability and durability are successfully demonstrated. This study is a promising distributed power source technology to drive electronics in gentle wind outdoor environments.

Improving Relative Permittivity and Suppressing Dielectric Loss of Triboelectric Layers for High-Performance Wearable Electricity Generation

High relative permittivity and low dielectric loss are two desired parameters of a triboelectric layer to enhance its mechanical-to-electrical energy conversion efficiency in a triboelectric nanogenerator (TENG). However, the elevated permittivity of the triboelectric layer is always accompanied by increasing dielectric loss, limiting further improvement or even reducing the electrical output. Herein, we report a method for improving the relative permittivity and suppressing the dielectric loss of the triboelectric layer via nanoscale design at the particle-polymer interface. When incorporated with 2 wt % Ag@C, the triboelectric-layer-enhanced TENG (TLE-TENG) presents a 2.6-fold increment in relative permittivity and a 302% current enhancement. An instantaneous peak power density of 1.22 W m-2, an excellent pressure sensitivity of 90.95 V kPa-1, and an optimized sheet resistance (∼0.14 Ω/sq) are attributes of this greatly enhanced device. Such improvements bode well for the implementation of these enhancing strategies to help position TLE-TENGs as pervasive and sustainable power sources and active self-powered sensors in the era of the Internet of Things.

Green-in-green biohybrids as transient biotriboelectric nanogenerators

Green self-powered devices based on biodegradable materials have attracted widespread attention. Here, we propose the construction of the transient biotriboelectric nanogenerator (TENG) using green-in-green bionanocompoites. The green-in-green nanocomposites, cellulose nanocrystal (CNC)/polyhydroxybutyrate (PHB), are prepared with a high-pressure molding method. The CNC promotes the degradation and enhances the dielectric constant of CNC/PHB. It further allows for the significant improvement of the triboelectric output of CNC/PHB-based TENG. The voltage output and current output of CNC/PHB-based TENG are 5.7 and 12.5 times higher than those of pristine PHB-based TENG, respectively. Also, the bio-TENG exhibits admirable signal stability in over 20000 cycles. Despite the high hardness of CNC/PHB, a soft but simple-structured arch sensor is successfully assembled using CNC/PHB-based TENG. It can attain the precise real-time monitoring of various human motions. This study may provide new insights into the design/fabrication of green functional materials, and initiate the next wave of innovations in eco-friendly self-powered devices.

Multi-output AC/DC triboelectric generator with dual rectification

Triboelectric generators (TEGs) are state-of-the-art powering solutions for low-power Internet of Things (IoT) devices. TEGs convert periodic mechanical vibrations into cyclic charge flow between electrodes, establishing an alternating current (AC). AC output requires rectification prior to charging any load, creating additional circuitry and power requirements. In recent years, the focus has shifted towards developing direct current (DC) generators as potential direct powering solutions. In this work, a DC–TEG is realized using a novel topology involving mechanical switching between a pair of metal contacts. This switching is implemented in vertical contact-separation mode and therefore does not involve any significant friction between the electrodes and metal contacts, overcoming the major limitation of wear and tear in conventional mechanical switching DC–TEGs. The proposed device can obtain each half-cycle rectified output across distinct electrode pairs, which is crucial for conditioning the asymmetric output of the TEGs. An AC output can be simultaneously harvested between the pair of bottom electrodes. The complementary AC–DC outputs of this device can supply power to multiple loads at a time, or coupled together to produce an enhanced output. Placing two complementary TEG pairs adjacent to each other in this topology has the advantage of reducing the ambient electric field, which is critical in improving the charge retention capability of the TEG layers. The proposed device achieves peak instantaneous power of 1.05 μW for the DC output and 1.12 μW for the AC output across a 7 MΩ resistance. The applications of the device in driving commercial electronics, harvesting biomechanical energy, and as progressive alarming system are demonstrated. Due to its simple, flexible topology and AC-DC dual output, this device has the potential for powering multiple loads and applications in diverse scenarios.

CMOS UWB 레이다 센서의 첨두전력 계산에 관한 연구

This paper presents the calculation of the approximate peak power of an ultra-wideband (UWB) pulse based on average power and 10 dB bandwidth measured using a spectrum analyzer. The instantaneous peak power of the UWB pulse signal converted from the instantaneous peak voltage measured using an oscilloscope and the result of the proposed calculation method are compared and shown to be approximately equal. A 3~5 GHz CMOS UWB radar sensor is used for verification. The center frequency, pulse repetition frequency, and bandwidth are 4 GHz, 10 MHz, and 10 dB, respectively. The center frequency and pulse repetition frequency are 4 GHz and 10 MHz respectively. 10 dB bandwidth can be adjusted in the range 500 MHz to 1 GHz. The test was performed while varying amplitude and 10 dB bandwidth of UWB pulse. And the resolution bandwidth of the spectrum analyzer was also varied. The result indicates an error of approximately 0.05~1.7 dB.

From Hazardous Waste to Green Applications: Selective Surface Functionalization of Waste Cigarette Filters for High-Performance Robust Triboelectric Nanogenerators and CO2 Adsorbents.

This article reports a novel and rational approach to convert waste cigarette filters (CFs), one of the largest sources of ocean pollution, into high-performance triboelectric nanogenerators (TENGs) and efficient CO2-capturing adsorbents. CFs are plasticized cellulose acetate, which take several years to degrade. To revalorize these fibers, selective amine surface functionalization is performed (10PAL-20T-CFs). For the proof of concept, when the modified fibers are employed in a TENG, it could generate an output voltage (96.63 V) and current (9.37 μA) that are, respectively, 43 and 8 times higher than those obtained employing the pristine CFs for the nanogenerator. The proposed TENG displays an instantaneous peak power of 3.75 mW, which is higher than that of many recently reported TENGs made from cellulose materials. Moreover, the TENG displayed outstanding durability to humidity and high-performance stability when it is subjected to cyclic loading (i.e., 12,000 cycles of loading-unloading). A 9 cm2 TENG could effectively light up 100 or more colored light-emitting diodes when it is manually pressed. Finally, the modified filter fibers show an excellent CO2 adsorption capacity of 1.93 mmol/g, which is 9.2 times higher than that obtained using the pristine fibers. These results demonstrate that hazardous wastes such as CFs can be upcycled into valuable resources.

Biomass-Based Functionalized Graphene for Self-Rechargeable Zinc–Air Batteries

Commercial batteries are typically charged with electrical power systems and consume electrical energy for recharging. Chemically self-charging batteries are a class of electrochemical devices that use chemical reactions to recharge batteries without electrical grids. Herein, we report the fabrication of a self-rechargeable zinc–air battery that is capable of simultaneously harnessing and storing energy based on biomass-derived functionalized graphene nanosheets (f-GNS). The chemical energy was harnessed into electric power by the spontaneous and reversible redox reactions between the f-GNS and atmospheric oxygen. This enables the fabrication of an energy storage device capable of self-charging without using any catalyst or organic dye. For the realization of integrated energy harvesting, conversion, and storage by a facile and sustainable approach, the f-GNS synthesized by the hydrothermal carbonization of pears followed by mild acid oxidation was used as the active material in an alkaline solution. The self-rechargeable zinc–air battery delivered an initial open circuit voltage of ∼1.15 V and a maximum instantaneous peak power density of ∼250 mW cm–2. The zinc–air batteries can charge themselves at rest in 15 min and exhibit high reversibility and excellent durability over prolonged charge and discharge cycles. When connected in series and parallel, the zinc–air batteries can offer the desired voltage and current, respectively, for practical applications. This work opens an avenue for further advancement in the design of self-sustainable, next-generation aqueous zinc–air batteries for practical applications.

Research on Maximum Efficiency Output Control of Voltage Controlled Adjustable Constant Current Source

Voltage controlled adjustable constant current source has simple structure and high output precision, but its high switching power consumption and low output power efficiency under current variation hinder the development of its high current application. A maximum efficiency output control method of constant current source based on small signal model is presented to reduce switching loss and achieve high efficiency output. A 0-4A adjustable constant current source prototype was built to verify the theory, and the experimental results show that when the setting current changes from 1 to 4A, the output dynamic response of the experimental group is rapid, the instantaneous peak power of MOS transistor is only 6.04w, and compared with the control group, the average efficiency of the system is from 85.85% up to 92.86%, which indicate a better power consumption control ability.

Anti‐Freezing Self‐Adhesive Self‐Healing Degradable Touch Panel with Ultra‐Stretchable Performance Based on Transparent Triboelectric Nanogenerators

AbstractThe development of next‐generation touch panels requires sensors that are highly sensitive, biocompatible, transparent, stretchable, self‐healing, and even anti‐freezing and self‐powered because the traditional touch panel based on stiff and brittle electrodes faces many challenges. Conductive hydrogels hold great promise as sensing materials for the new‐generation touch panel. However, most hydrogel‐based touch panels are developed based on single‐function gel materials with a lack of the anti‐freezing and self‐power capabilities. Herein, the authors demonstrate a multi‐functional surface‐capacitive touch panel based on a triboelectric nanogenerator with an instantaneous peak power density of 209 mW m−2 that uses zwitterionic network hydrogels as a highly transparent (98.1% transmittance), ultra‐stretchable (>11 500% strain), degradable, and flexible ionic conductor. The panel can be utilized as a human‐machine interactive interface with fast response, high resolution, low parasitic capacitance, functional recovery instantly upon damage, and without sacrificing its functionalities even in the high stretch state (1600% areal strain) and at the subzero environment (<−20 °C). Epidermal touch panels are operated on arbitrary and complex surfaces, with outstanding input property demonstrated by writing, and playing computer games. Simultaneously, the multifunctional touch panel is degradable in phosphate buffered saline solution, and no pollution is caused.

Peak Power Minimization for Commercial Thermostatically Controlled Loads in Multi-Unit Grid-Interactive Efficient Buildings

The load profiles of most commercial and industrial consumers are characterized by brief periods of very high power consumption followed by intervals of lower demand. To encourage such consumers to flatten their load profiles, power utilities around the world often levy a monthly demand charge (DC) on the peak demand measured over brief intervals. In this work, we consider the joint optimization of energy costs (EC) and the instantaneous peak power of a multi-unit building which uses a hydronic heating, ventilation and air-conditioning (HVAC) system and responds to a demand response (DR) program. Despite the apparent non-convexity of the control framework, we show how it may be transformed into a convex optimization problem. Next, we study the power demand patterns resulting from our proposed strategy for thermostatically controlled loads (TCLs), and evaluate the strategy’s performance for various climate zones in the US under both typical and atypical weather conditions. The results show that, depending on the ambient conditions and the tariff structure, our strategy can result in utility bill savings of up to nearly 19% compared to the baseline. The results also indicate that our power control strategy can significantly reduce the instantaneous peak power consumption in commercial TCLs.