MΩ Resistor Research Articles

Graphene reinforced cement-based triboelectric nanogenerator for efficient energy harvesting in civil infrastructure

This paper investigated a graphene reinforced cement-based triboelectric nanogenerator (TENG) aimed at harvesting mechanical energies in infrastructure, such as pedestrians, vehicles, human-induced vibrations, and natural stimulus like wind and earthquakes. The triboelectric layers of the cement-based TENG consisted of a fully cured graphene modified cement-based plate and a polytetrafluoroethylene (PTFE) film, which were tested under a contact-separation mode. Microstructural analysis indicated that the graphene was well-dispersed in the cementitious matrix, and the graphene-cement composites achieved excellent compressive and flexural strengths of 53.0 and 3.5 MPa, respectively. The electrical characteristics of the graphene-cement composites, specifically their resistivity and impedance, showed that they did not reach the percolation threshold, making them ideal dielectric materials with a dielectric constant of 100 at 1 kHz. The performance of the cement-based triboelectric nanogenerator (TENG) varied depending on the amplitude and frequency of the contact-separation cycle. At a frequency of 10 Hz and under a force of 100 N, the short-circuit current and open-circuit voltage peaked at 3.62 µA and 279.4 V, respectively, achieving a maximum power density of 95 mW/m2 with a 100 MΩ resistor. In practical applications, this TENG charged a 10 μF capacitor to 3.1 V within one minute and to 57.2 V in one hour. Additionally, manual operation of the TENG enabled the lighting of 29 LEDs with one minute of hand pressure. By utilizing triboelectric effects, the results provide the feasibility of self-powering concrete structures and pavements for future smart cities.

The MnAl-alloy nanoparticles incorporated PVDF-based piezoelectric nanogenerator as a self-powered real-time pedometer sensor

This study introduces a flexible, sensitive, and cost-effective hybrid piezoelectric nanogenerator (PENG) by integrating MnAl-alloy nanoparticles into a poly (vinylidene fluoride) (PVDF) nanocomposite film. The MnAl-alloy nanoparticles serve as a nucleating agent for promoting the formation of the electroactive β-phase. It is observed that the electroactive β-phase, dielectric permittivity, saturation polarization, and output performance of the device improve with the incorporation of the MnAl-alloy nanoparticles up to 7.5 wt. % in the PVDF matrix. Hence, in this work, we report a MnAl-alloy-based optimized piezoelectric nanogenerator device using a free-standing nanofiber mat (7.5 wt. % MnAl-alloy) prepared by the electrospinning technique. The as-fabricated piezoelectric nanogenerator effectively channels charges generated by mechanical stress to the electrodes, resulting in an impressive output voltage of approximately 16 V and an output current of around 7.1 μA, yielding a power of 47 μW across 4.5 MΩ resistor. Furthermore, energy harvesting from human movements such as jogging, knee bending, and walking is demonstrated for practical application. A piezo potential of approximately 8 V generated during walking showcases the development of a self-powered pedometer. Furthermore, tapping the PENG charges a capacitor of 0.1 μF up to approximately 1 V, demonstrating the potential application for the power up of small portable electronic devices.

Polymer-metal film induced ultrahigh output TVNG and self-powered intelligent sensor system assisted by EEMD

Tribovoltaic nanogenerators (TVNGs) based on tribovoltaic effect can output DC current directly, and has the advantages of high output current density and low internal resistance. While TVNGs have been restricted by its low output voltage and power. Herein, we have developed a metal-polymer film with a micro-uneven structure on the surface, much higher corrosion resistance and wear resistance than metal. On this basis, a centimeter-level sliding structure metal-EP/GaN-TVNG has been fabricated, which shows a high and stable long-term DC electrical output (a maximized power output of 4.19 W/m2 when matched with a 0.07 MΩ resistor, a stable output current of 2.25 A/m2 and a peak Voc of 27 V). Further, a TVNG vehicle travelling intelligent sensor and system which can integrate electrical signals collected by TVNG into digital signal processing algorithms and then feed backing to the driving system, has been designed and manufactured. As an effective method for deep analysis of signals, Ensemble Empirical Mode Decomposition (EEMD) has been used for the first time for deep processing of nanogenerator signals in this work. This work provides a new model of further development of high output TVNG and a new deep signal processing methods of TVNG/TENG signal.

The investigation of the energy harvesting performance using electrospun PTFE/PVDF based on a triboelectric assembly

This work presents an investigation into the energy harvesting performance of a combination of polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF) materials prepared using a one-step electrospinning technique. Before electrospinning, different percentages of the 1 micron PTFE powder were added to a PVDF precursor. The surface morphology of the electrospun PTFE/PVDF fibre was investigated using a scanning electron microscope and tunnelling electron microscope. The structure was investigated using Fourier-transform infrared spectroscopy and x-ray diffraction analysis (XRD). A highly porous structure was observed with a mix of the α- and β-phase PVDF. The amount of β-phase was found to reduce when increasing the percentage of PTFE. The maximum amount of PTFE that could be added and still be successfully electrospun was 20%. This percentage showed the highest energy harvesting performance of the different PTFE/PVDF combinations. Electrospun fibres with different percentages of PTFE were deployed in a triboelectric energy harvester operating in the contact separation mode and the open circuit voltage and short circuit current were obtained at frequencies of 4–9 Hz. The 20% PTFE fibre showed 4 (51–202 V) and 7 times (1.3–9.04 µA) the voltage and current output respectively when compared with the 100% PVDF fibre. The V oc and I sc were measured for different load resistances from 1 kΩ to 6 GΩ and achieved a maximum power density of 348.5 mW m−2 with a 10 MΩ resistance. The energy stored in capacitors 0.1, 0.47, 1, and 10 µF from a book shaped PTFE/PVDF energy harvester were 1.0, 16.7, 41.2 and 136.8 µJ, respectively. The electrospun fibre is compatible with wearable and e-textile applications as it is breathable and flexible. The electrospun PTFE/PVDF was assembled into shoe insoles to demonstrate energy harvesting performance in a practical application.

Using multi-criteria decision-making approach for material alternatives in TiO2/P(VDF-TrFE)/PDMS based hybrid nanogenerator as a wearable device

P(VDF-TrFE)/TiO2/PDMS-based hybrid nanogenerators with excellent piezoelectric performance are of particular interest for the development of sensors, wearable devices, and low-cost biomechanical energy harvesters. In this work, hybrid nanogenerator (HNG) is designed to enhance the energy output by integrating piezoelectric and triboelectric effects. P(VDF-TrFE)/TiO2 nanocomposites are synthesized using electrospinning to design hybrid nanogenerator for energy harvesting from a manual activity. The hybrid nanogenerator device generated 5.36 µA current across 10 MΩ resistor and 52 V electric voltage. An analysis of the effect of varying TiO2 on hybrid nanogenerators is reported here for the first time. The best material for biomechanical energy harvesting applications is selected using a multi-criteria decision-making (MCDM) based material selection and optimization technique TODIM, along with a sensitivity study. SA-4 type nanocomposite is the most suitable material as per the TODIM approach. This nanogenerator shows better performance than most nanogenerators designed with complex and sophisticated approaches.

Low-dimensional halide perovskite/PVDF nanocomposite with enhanced piezoelectricity as flexible biomechanical energy harvester

Sustainable energy harvesting is the need of the hour, and piezoelectric nanogenerators (PENG) offer tremendous opportunities in this field. We have investigated the mechanical energy harvesting applications of a nanocomposite comprising a low-dimensional halide perovskite (HP) and polyvinylidene fluoride (PVDF). Cs4PbBr6 HP was prepared using mechanochemical synthesis, and a composite film of PVDF with Cs4PbBr6 was utilized as the PENG to scavenge energy from day-to-day human biomechanical activities. The properties and output results of the fabricated devices with changing weight percentages (wt.%) of HP used as nanofillers in the PVDF matrix are compared to those of a pure PVDF. A 6 wt.% concentration of Cs4PbBr6 induces the composite's electroactive β-phase to around 87%. The polarization hysteresis (P-E) loop measurement reveals a remanent polarization of 0.31 µC/cm2. The measured piezoelectric coefficient (d33) is about ⁓12 pm/V, and the piezoelectric amplitude is ∼500 pm for the optimized PENG at the maximum applied bias of ±30 V. The device shows an instantaneous output voltage of ⁓90 V, a current of ⁓3.8 μA, and power of ⁓80 µW across a 5 MΩ resistor. Simple daily human activities like finger tapping, leg-toe pressing, finger bending, heel pressing, and walking are used to generate output voltages using PENG with prospective usage in powering portable electronic devices. The output AC voltage of the device is employed to charge a 10 µF capacitor up to ∼3.5 V and shows exceptional stability over long cycles. The output power generated is adequate for lighting commercial LEDs without any external input. The Cs4PbBr6/PVDF composite films thus demonstrate significant potential to be deployed as high-performance, portable, and wearable mechanical energy harvesting devices.

Stiffness Modulation in Flexible Rotational Triboelectric Nanogenerators for Dual Enhancement of Power and Reliability.

Rotational nanogenerators with flexible triboelectric layers have wide applications and high reliability. However, flexible materials cause a severe reduction in contact force and thus triboelectric output power. Unlike previous works devising complex auxiliary structures to solve this issue, this paper focuses on improving the contact material mechanics and proposes a stiffness modulation method. By introducing fine patterns to the contacting rotor-stator pairs, the effective elastic modulus was regulated from approximately 103 to 105 MPa, and the output voltage was modulated from approximately 24.39% to 375.87% compared to the non-patterned rotor-stator pairs, corresponding to a maximal a 14 times increase in output power. A maximal power density of 18.75 W/m2 was achieved on 10 MΩ resistance at 9.6 Hz, which is even beyond the power density of most rigid triboelectric interfaces. Moreover, high reliability could be maintained when the volume ratio of the horizontal patterns exceeded a threshold value of 33.5% as the stator and 63.6% as the rotor for a 0.5 mm linewidth. These results prove the efficacy of the stiffness modulation method for jointly achieving high output power and high reliability in flexible rotational triboelectric nanogenerators.

High powered output flexible aerogel triboelectric nanogenerator under ultrahigh temperature condition

Triboelectric nanogenerators (TENGs) have emerged as promising devices for harvesting low-frequency energy, but its application in high-temperature environments is limited. In this article, a flexible high-temperature resistant fiber substrate material was developed using needled felt and silicon aerogel. This material demonstrated exceptional resistance, withstanding exposure to a butane flame at approximately 1300 ℃ for a minimum of 10 min without experiencing burn-through. Following the application of electrodes and protective encapsulating, a high-temperature resistant silicon aerogel and fiber felts based triboelectric nanogenerator (HTFs-TENG) was successfully created. In addition, we achieved remarkable enhancements in the electrical output performance of the HTFs-TENG by precisely regulating its dielectric properties, resulting in an impressive increase in peak voltage from 17 V to 135 V. The current output increased from 1.4 μA to 6 μA. The HTFs-TENG demonstrated remarkable adaptability, operating effectively at temperatures as high as 275 ℃ and as low as approximately − 75 ℃. Moreover, it showcased an instantaneous power density output of 31.9 mW/m2 under a 100 MΩ resistance load. The HTFs-TENG displayed impressive electrical signal response capabilities at ultralow frequencies (≤1 Hz) across various temperatures and frequencies, positioning it as an ideal self-powered vibration sensor and temperature sensor for diverse generator applications.

3D‐Printed Multi‐scale Fluidics for Liquid Metals

AbstractRoom‐temperature eutectic Gallium Indium (eGaIn)‐based devices offer stretchable, conductive, and reconfigurable properties for robotics, communications, and medicine. Microfluidics enables eGaIn device creation, but these typically have larger feature sizes. Recent three‐dimensional (3D) printing advancements, particularly direct laser writing (DLW), allow for sub‐100 µm microfluidic devices. However, interfacing DLW microfluidics with larger systems poses challenges in channel resist removal, eGaIn filling, and electrical integration, limiting micro‐scale liquid metal device application. This study introduces a multiscale, cost‐effective, three‐step process combining DLW‐fluidic microchannels with centimeter‐scale substrates made via stereolithography (SLA). It establishes a robust interface between independently printed materials and simplifies eGaIn filling in microfluidic channels as small as 50 µm, potentially enabling smaller liquid metal features. The research also presents eGaIn coils with 43–770 mΩ resistance and 2–4 nH inductance. This process facilitates low‐temperature, conductive, flexible interfaces for sensors, actuators, and circuits, and expands the range for size‐dependent properties of passive electronic components like resistors, capacitors, and inductors from liquid metal.

The triboelectric sensor based on PDMS/SGO for human running posture and physical fitness health monitoring

ABSTRACT Recently, research about the intelligent sports equipment based on triboelectric sensor for athlete posture monitoring has made progress. However, the exploration of new triboelectric materials remains an important challenge to be faced. Hence, we ingeniously design a polydimethylsiloxane (PDMS)/silanized graphite oxide (SGO)-based triboelectric nanogenerator (PS-TENG) for running posture and physical health monitoring. The introduction of SGO has improved the electron capture capability of PDMS, thereby achieving high output of PS-TENG. From the results, under an 60 MΩ resistance, the power density of PS-TENG reaches a peak of 1780 mW·m−2. Furthermore, athletes undergo various postures during the running process, so monitoring special postures is very meaningful, such as jogging, long jump, walking, etc. Especially, according to the self-charging mechanism, PS-TENG can indirectly evaluate physical energy analysis during running by storing electrical energy in capacitors. This triboelectric sensor can assist in posture monitoring and physical fitness monitoring during running.

Halide Tunablility Leads to Enhanced Biomechanical Energy Harvesting in Lead-Free Cs2SnX6-PVDF Composites.

The main challenges impeding the widespread use of organic-inorganic lead halide perovskites in modern-day technological devices are their long-term instability and lead contamination. Among other environmentally convivial and sustainable alternatives, Cs2SnX6 (X = Cl, Br, and I) compounds have shown promise as ambient-stable, lead-free materials for energy harvesting, and optoelectronic applications. Additionally, they have demonstrated tremendous potential for the fabrication of self-powered nanogenerators in conjunction with piezoelectric polymers like polyvinylidene-fluoride (PVDF). We report on the fabrication of composites constituting solvothermally synthesized Cs2SnX6 nanostructures and PVDF. The electroactive phases in PVDF were boosted by the incorporation of Cs2SnX6, leading to enhanced piezoelectricity in the composites. First-principles density functional theory (DFT) studies were carried out to understand the interfacial interaction between the Cs2SnX6 and PVDF, which unravels the mechanism of physisorption between the perovskite and PVDF, leading to enhanced piezoresponse. The halide ions in the inorganic Cs2SnX6 perovskites were varied systematically, and the piezoelectric behaviors of the respective piezoelectric nanogenerators (PENGs) were investigated. Further, the dielectric properties of these halide perovskite-based hybrids are quantified, and their piezoresponse amplitude, piezoelectric output signals, and charging capacity are also evaluated. Out of the several films fabricated, the optimized Cs2SnI6_PVDF film shows a piezoelectric coefficient (d33) value of ∼200 pm V-1 and a remanent polarization of ∼0.74 μC cm-2 estimated from piezoresponse force microscopy and polarization hysteresis loop measurement, respectively. The optimized Cs2SnI6_PVDF-based device produced an instantaneous output voltage of ∼167 V, a current of ∼5.0 μA, and a power of ∼835 μW across a 5 MΩ resistor when subjected to periodic vertical compression. The output voltage of this device is used to charge a capacitor with a 10 μF capacitance up to 2.2 V, which is then used to power some commercial LEDs. In addition to being used as a pressure sensor, the device is employed to monitor human physiological activities. The device demonstrates excellent operational durability over a span of several months in an ambient environment vouching for its exceptional potential in application to mechanical energy harvesting and pressure sensing applications.

Static and Dynamic Analysis of a Bistable Frequency Up-Converter Piezoelectric Energy Harvester

Using energy harvesting to convert ambient vibrations efficiently to electrical energy has become a worthy concept in recent years. Nevertheless, the low frequencies of the ambient vibrations cannot be effectively converted to power using traditional harvesters. Therefore, a frequency up-conversion harvester is presented to convert the low-frequency vibrations to high-frequency vibrations utilizing magnetic coupling. The presented harvester consists of a low-frequency beam (LFB) and a high-frequency beam (HFB) with identical tip magnets facing each other at the same polarity. The HFB, fully covered by a piezoelectric strip, is utilized for voltage generation. The dynamic behavior of the system and the corresponding generated voltage signal has been investigated by modeling the system as a two-degrees-of-freedom (2DOF) lumped-parameter model. A threshold distance of 15 mm that divides the system into a monostable regime with a weak magnetic coupling and a bistable regime with a strong magnetic coupling was revealed in the static analysis of the system. Hardening and softening behaviors were reported at the low frequency range for the mono and bistable regimes, respectively. In addition, a combined nonlinear hardening and softening behavior was captured for low frequencies at the threshold distance. Furthermore, a 100% increment was achieved in the generated voltage at the threshold compared to the monostable regime, and the maximum generated voltage was found to be in the bistable regime. The simulated results were validated experimentally. Moreover, the effect of the external resistance was investigated, and a 2 MΩ resistance was found to be optimal for maximizing the generated power. It was found that frequency up-converting based on magnetic nonlinearity can effectively scavenge energy from low-frequency external vibrations.

Preferential perovskite surface-termination induced high piezoresponse in lead-free in situ fabricated Cs3Bi2Br9-PVDF nanocomposites promotes biomechanical energy harvesting.

Lead-free halide perovskites have gained immense popularity in photovoltaic and energy harvesting applications because of their excellent optical and electrical attributes with minimal toxicity. We synthesized composite films of lead-free Cs3Bi2Br9 perovskite embedded in the polyvinylidene fluoride (PVDF) matrix and have investigated their piezoelectric energy harvesting. Five PVDF@Cs3Bi2Br9 composite films were fabricated with varying wt% of the perovskite in the PVDF. The composite with a 4 wt% of the perovskite shows 85% activation of the electroactive β-phase of PVDF. Additionally, this composite exhibits a maximum polarisation of ∼0.1 μC cm-2 and the best energy storage density of ∼0.8 mJ cm-3 at an applied field of ∼16 kV cm-1 among all the synthesized composites. A nanogenerator fabricated using 4 wt% loading in the composite film produced an instantaneous output voltage of ∼40 V, an instantaneous current of ∼4.1 μA, and a power density of ∼17.8 μW cm-2 across 10 MΩ resistance when repeatedly hammered by the human hand. The nanogenerator is further employed to light up several LEDs and to charge capacitors with a small active area demonstrating significant promise for prospective wearables and portable devices and paving the way for high-performance nanogenerators using lead-free halide perovskites. Density functional theory calculations were performed to understand the interaction of the electroactive phase of the PVDF with different perovskite surface terminations to unravel the various interaction mechanisms and their ensuing charge transfer properties.

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.

High-Performance Triboelectric Nanogenerators Based on Commercial Textiles: Electrospun Nylon 66 Nanofibers on Silk and PVDF on Polyester.

A high-performance textile triboelectric nanogenerator is developed based on the common commercial fabrics silk and polyester (PET). Electrospun nylon 66 nanofibers were used to boost the tribo-positive performance of silk, and a poly(vinylidene difluoride) (PVDF) coating was deployed to increase the tribo-negativity of PET. The modifications confer a very significant boost in performance: output voltage and short-circuit current density increased ∼17 times (5.85 to 100 V) and ∼16 times (1.6 to 24.5 mA/m2), respectively, compared with the Silk/PET baseline. The maximum power density was 280 mW/m2 at a 4 MΩ resistance. The performance boost likely results from enhancing the tribo-positivity (and tribo-negativity) of the contact layers and from increased contact area facilitated by the electrospun nanofibers. Excellent stability and durability were demonstrated: the nylon nanofibers and PVDF coating provide high output, while the silk and PET substrate fabrics confer strength and flexibility. Rapid capacitor charging rates of 0.045 V/s (2 μF), 0.031 V/s (10 μF), and 0.011 V/s (22 μF) were demonstrated. Advantages include high output, a fully textile structure with excellent flexibility, and construction based on cost-effective commercial fabrics. The device is ideal as a power source for wearable electronic devices, and the approach can easily be deployed for other textiles.

Self-powered sensing of power transmission lines galloping based on piezoelectric energy harvesting

Online monitoring sensors are a feasible solution for conductor galloping that greatly harms the stable operation of power transmission systems. However, power supply that drives sensors has become one of the bottlenecks restricting the development of distributed sensing systems. This work initially proposes harvesting the energy of conductor galloping and joint utilization to assess conductor galloping degree. A swinging piezoelectric energy harvester based on frequency boost conversion is also proposed. The output characteristics of harvester and the physical validation of the scale model of power transmission line galloping are further explored. Experiment results showed a maximum output voltage and current of 29.6 V and 29 µA, respectively, under the characteristic conditions of conductor galloping. The corresponding load capacity of the harvester reached a maximum power output of 155.58 µW under minimum resistance of 70 kΩ at 35 cm vibration amplitude and 1.3 Hz frequency. The conductor galloping testing platform indicated that the frequency boost conversion effect was weakened due to the occurrence of torsion movement during conductor galloping, and the output presented a nonlinear variation with the vibration amplitude and frequency. The degree and direction of conductor galloping can be preliminarily judged according to the output trend, and the maximum output power of load capacity of the harvester reached 101.5 μW under 107 MΩ resistance at 1.3 Hz vibration frequency, validating that the proposed energy harvesting system is promising for self-powered sensing applications in low-power monitoring sensors for conductor galloping.© 2017 Elsevier Inc. All rights reserved.

Lithium‐Ion Battery Testing Capable of Simulating “Ultralow” Lunar Temperatures

The first‐ever lithium‐ion battery cycler capable of testing the coin and pouch cells under ultralow (≤40 °C) temperatures down to −175 °C to simulate extreme climates found in the lunar and space missions, high‐altitude air vehicles, polar regions of Earth, and military expeditionary missions is enthusiastically reported. The extremely cold temperatures are achieved through a tailored extreme low‐temperature system (ELTS) with liquid nitrogen flow and the ability to reach temperatures between −175 and 25 °C, using 1 kΩ and 1 MΩ resistors at varying currents of 1–4 mA and 1–4 μA, respectively, is validated. Employing the ELTS, Li4Ti5O12 (LTO)||Li cells with 1 m lithium bis(fluorosulfonyl)imide in cyclopentyl methyl ether as an electrolyte developed in this research group are charged and discharged at room temperature (cycling rate C/5), −20 (C/10), −40 (C/40), and −60 °C (C/50), which exhibited discharge capacities of 159.04, 119.12, 101.79, and 33.06 mAh g−1, respectively. Moreover, the LTO||Li cell produced a reversible capacity of 7.12 mAh g−1 tested at −100 °C for the first time.

Switchless Oscillating Charge Pump-Based Triboelectric Nanogenerator and an Additional Electromagnetic Generator for Harvesting Vertical Vibration Energy.

According to energy crisis and increasing number of small electronics, energy harvesting is one of the most promising technologies for scavenging several types of wasted energy. Especially, with regard to vibrational energy harvesting, triboelectric nanogenerators and electromagnetic generators stand out due to their working mechanisms. Here, an oscillating charge pump-based hybrid generator with two triboelectric nanogenerators and an electromagnetic generator using a switching-free characteristic was fabricated with material optimization. To enhance the electrical output of the triboelectric nanogenerator, a concept of charge pumping with simply connecting an additional charge pump device and the nanostructure formation process on the contact metal layer were adopted. The electrical outputs were characterized as an output current of 9.17 μA with a current density of 83.2 mA m-3 in the triboelectric nanogenerator. The power density of the triboelectric nanogenerator reached 4.45 W m-3 with a 40 MΩ resistor. The electromagnetic generator showed an output current density of 0.91 A m-2. Moreover, with the cuboid structure, the device can sense the collision force with different angular displacements from 5 to 30°. The proposed hybrid generator with a simple structure can be applied to sensing applications with the one-point-fixed state.

Influence of Various Physiochemical Parameters of AFeO3 (A = Bi, Er, Ga, La, Sm, Y) Fillers on the Dielectric, Ferroelectric, Energy Storage, and Mechanical Energy Harvesting Performance of PVDF

AbstractDifferent filler particles are very often used by researchers all over the world to tune the dielectric, ferroelectric, piezoelectric, energy storage, and energy harvesting properties of poly(vinylidene fluoride) (PVDF). In the present work, different perovskite ferrites, AFeO3 (A = Bi, Er, Ga, La, Sm, and Y), are included into PVDF matrix separately. The roles of different parameters like, particle size, dielectric permittivity, ferroelectric polarization, crystal structure, etc. of the fillers in tuning the performance of respective PVDF‐based composites are comprehensively and simultaneously studied here. Non‐centrosymmetric fillers are found to improve the output performances of PVDF more effectively compared to that of centrosymmetric fillers. 5 wt% BiFeO3‐loaded PVDF film (5BF) shows the best performance in all aspects. Upon repeated human finger tapping, the maximum instantaneous output power density and instantaneous current across a 10 MΩ resistor connected across the 5BF film are found to be ≈3 µW cm−2 and 1.25 µA, respectively. The rectified voltage from 5BF nanogenerator is used to charge a 10 µF commercial capacitor up to ≈2.8 V and lights up some LEDs as a part of its real life applicability. The fabricated nanogenerator also shows good vibration and pressure sensing ability.

Temporal gas temperature of atmospheric pressure air plasma

In this paper, temporal gas temperature in plasma was measured by Rayleigh scattering in a passive way since synchronization was difficult due to the randomness of current pulses. The plasma was generated between a 10 mm pin-to-plane gap connected to a H.V DC voltage through a 130 MΩ resistor and a skin sample was placed on a grounded plate. Even the plasma can be touched by a human hand without any feeling of warmth, the peak temperature could be 337 K then decrease to 295 K over 60 μs at 1 mm. Moreover, the applied voltage dramatically affects peak current and the peak temperature. Therefore, the transient “high” temperature cannot be touched and the so-called “cold” plasma might not be “cold”.