Voltage Generator Research Articles

Spider Webs‐Inspired Aluminum Coordination Hydrogel Piezoionic Sensors for Tactile Nerve Systems

AbstractPiezoionics, a new frontier that employs mobile ions as energy and charge carriers, plays an important role in new energy and intelligent electronics. However, a significant challenge consists in balancing the structural design of metal ions coordination hydrogel (HG‐MI) piezoionics for current conduction, voltage generation, and especially mechanical adaptability. Herein, inspired by the spider webs' unique structure, a strategy by realizing the full potential of metal‐ligand ions ([(OH)Cl2]3−) to facilitate the keggin‐type structure AlOHAlOH generation together with activate functional carboxyls is introduced. Impressively, the whole property of the product HG‐AlPAC, especially the mechanical performance is improved. For example, the toughness of HG‐AlPAC is 2.75 MJ m−3, more than twofold that of traditional HG‐AlAS/AC/AN samples. Due to the stable fixation of ─Al─OH─ thus promoting Cl− separation upon external force, HG‐AlPAC achieves a piezoionic coefficient of 0.89 mV KPa−1 and energy conversion efficiency of 1.29%, promising for mechanical‐electrical conversion and sensing. Combined with the good mechanical performance with the excellent piezoionic properties, underscores its potential as a tactile nerve system of analgesia patients to prevent them from being injured. This work intends to provide a stride toward mechanically robust self‐powered piezoionic sensors and offer insights into ionotropic materials for energy harvesting, human‐machine interaction, and biointerface.

Investigating the correlation between flow dynamics and flow-induced voltage generation

The conversion of water current to voltage generation through graphene has gained interest in both basic physics and applications such as sensors and electricity generation systems. However, many aspects of the mechanism remain unclear. Recently, quantum-based momentum transfer theories have been reported, but these often do not account for flow conditions. In this study, we investigated the correlation between the flow conditions of a liquid medium and the electrical conduction of graphene through experiments and numerical calculations. Our results suggest that the necessary condition is that the flow must be neither irregular nor purely laminar; instead, graphene responds to the transition process of the fluid. This finding supports the extension of current theories and presents valuable insights for both basic science and industrial applications.

From Sudoscan to bedside: theory, modalities, and application of electrochemical skin conductance in medical diagnostics

The human body has two main types of sweat glands: apocrine and eccrine. Eccrine glands are widely distributed across the skin, including areas with hair. While the eccrine glands on palms and soles help improve grip, those on the rest of the body primarily aid in thermoregulation. Sudomotor function, which controls sweating, is regulated by the sympathetic division of the autonomic nervous system through cholinergic and adrenergic pathways. The activation of eccrine glands involves intricate processes, including neurotransmitter binding, ion channel modulation, and voltage generation. Sudoscan technology utilizes electrochemical skin conductance (ESC) to non-invasively measure sudomotor function. This method, which has been standardized for accuracy, has established normative benchmarks and has proven reliable across diverse populations. Sudoscan’s diagnostic performance is comparable to invasive methods such as intraepidermal nerve fiber density testing, making it a valuable tool for diagnosing small fiber neuropathy. Moreover, it has been shown to correlate with corneal nerve fiber length, providing insights into various neuropathic conditions. Compared to traditional sudomotor function tests, Sudoscan proves superior in terms of its accessibility, simplicity, and reliability, with the potential to replace or complement existing diagnostic methods. It is important to differentiate ESC, as measured by Sudoscan, from other skin conductance measures, such as galvanic skin response (GSR) or electrodermal activity (EDA). Although these methods share a common physiological principle, ESC is specifically designed for diagnosing sudomotor function, unlike GSR/EDA, which is typically used for continuous monitoring. Sudoscan’s success has led to its integration into consumer health devices, such as the BodyScan from Withings, showcasing its versatility beyond clinical settings. Future research may explore ESC applications in diverse medical fields, leveraging real-world data from integrated consumer devices. Collaborative efforts between researchers and engineers promise to offer new insights into sudomotor function and its implications for broader health monitoring. This study provides a comprehensive overview of ESC, including topics such as eccrine gland physiology, sudomotor function, Sudoscan technology, normative benchmarks, diagnostic comparisons, and potential future applications.

Electrochemical kinetic energy harvesting mediated by ion solvation switching in two-immiscible liquid electrolyte

Kinetic energy harvesting has significant potential, but current methods, such as friction and deformation-based systems, require high-frequency inputs and highly durable materials. We report an electrochemical system using a two-phase immiscible liquid electrolyte and Prussian blue analogue electrodes for harvesting low-frequency kinetic energy. This system converts translational kinetic energy from the displacement of electrodes between electrolyte phases into electrical energy, achieving a peak power of 6.4 ± 0.08 μW cm−2, with a peak voltage of 96 mV and peak current density of 183 μA cm−2 using a 300 Ω load. This load is several thousand times smaller than those typically employed in conventional methods. The charge density reaches 2.73 mC cm−2, while the energy density is 116 μJ cm−2 during a harvesting cycle. Also, the system provides a continuous current flow of approximately 5 μA cm−2 at 0.005 Hz for 23 cycles without performance decay. The driving force behind voltage generation is the difference in solvation Gibbs free energy between the two electrolyte phases. Additionally, we demonstrate the system’s functionality in a microfluidic harvester, generating a maximum power density of 200 nW cm−2 by converting the kinetic energy to propel the electrolyte through the microfluidic channel into electricity.

Green conversion of waste polyester into few-layer graphene for interfacial solar-driven evaporation and hydroelectric electricity generation

The coupling of solar-driven interfacial evaporation with hydrovoltaic technology is emerged as a hopeful approach to alleviate energy crisis and freshwater shortage. However, constructing low-cost evaporators with high-performance freshwater and electricity co-generation and unveiling the co-generation mechanism remain a grand challenge. Herein, we report the green transformation of waste poly(ε-caprolactone) into graphene through a salt-assisted carbonization strategy and build a flexible bi-functional graphene-based evaporator for freshwater and electricity co-generation. The graphene exhibits a typical wrinkled structure with curved edges and is composed of 7–8 discontinuous layers with rich oxygen-containing groups. The graphene-based evaporator exhibits excellent sunlight absorption (98%), photo-to-thermal conversion property, good water transport ability, low water evaporation enthalpy, and low thermal conductivity of 0.06 W m−1 K−1. The evaporator not only exhibits a notable water evaporation rate (2.92 kg m−2 h−1), but also achieves the maximum output voltage of 310 mV, surpassing many previously reported evaporators/generators. The result of molecular dynamics simulation proves the diffusion difference between H+ and OH− in water and graphene, which eventually leads to the voltage generation. Not only will this work help to improve the upcycling of waste plastics and achieve carbon neutrality, but it will also open an avenue for co-generation of freshwater and electricity.

Enhanced methane and energy generation from sewage water using microbial fuel cells with paddy field soil substrate

Microbial fuel cells (MFCs) have potential in wastewater treatment, biogas production and clean energy generation. MFCs provide an interdisciplinary research approach incorporating engineering and natural sciences. This study explores MFCs’ capabilities to produce electricity and biogas from wastewater and field soil substrates with different compositions. A two-chamber MFC system was operated anaerobically. Household sewage water used as the organic substrate with different soil amounts. Six different process feed compositions, labeled MFC-1–6, were investigated. MFC-1 exhibited the highest biogas generation volume of 245 cm³ and 42 mW/cm² power density. MFC-5 and −6 yielded 100 cm³ and 130 cm³, respectively. Wastewater treatment was effective on day 20, with pH, conductivity, turbidity, and total dissolved solids decreased to 7.3, 2.6 mS, 326 NTUs, and 1114 mg/L, respectively. Since, MFC-1 autonomously generated −800 mV, an external battery supplied an additional 600 mV to meet the methane generation voltage requirements. MFCs’ effectiveness in addressing wastewater treatment and renewable energy production was highlighted.

Thermally Driven Spin Transport of Epitaxial FeRh Films with a Non-magnetic Pt Layer via the Longitudinal Spin Seebeck Effect.

FeRh has been demonstrated to be an important material for the observation of magnetic phase transitions, such as the first-order transition from an antiferromagnetic (AFM) to a ferromagnetic (FM) state, in response to changes in the temperature. This is because of the magnetic moment induced in Rh atoms above the magnetic phase transition temperature. In the present study, we focus on the longitudinal spin Seebeck effect (LSSE), which involves the generation of spin voltage as a result of a temperature gradient in FM materials or FM insulators, and experimentally assess the effect of the crystalline quality of FeRh films and the properties of the substrate on the LSSE thermopower during the FM-AFM phase transition. The measured LSSE thermopower of an epitaxial (110)-oriented FeRh film grown on an Al2O3 substrate is approximately 60 times higher than that of a polycrystalline FeRh film on a SiO2/Si substrate. This can be explained by the high magnetic sensitivity and superior FM properties of (110)-oriented epitaxial FeRh films. Furthermore, by comparing the transverse thermoelectric voltage for in-plane magnetized (IM) and perpendicularly magnetized (PM) configurations, we quantitively evaluate the contribution of the exclusive anomalous Nernst effect (ANE) to the LSSE signals in the FeRh/Al2O3 structure, finding it to be approximately 15-30% over a temperature range of 75-300 K. LSSE measurements in Pt/FeRh films are thus demonstrated to provide a versatile pathway for the development of thermoelectric power generation applications and other practical spintronics and neuromorphic computing devices.

Generating comprehensive lithium battery charging data with generative AI

In optimizing the performance and extending the lifespan of lithium batteries, accurate state prediction is crucial. Traditional regression and classification methods have achieved some success in predicting battery states. However, the effectiveness of these data-driven approaches largely depends on the availability and quality of public datasets. Additionally, generating electrochemical data primarily through battery experiments is a lengthy and costly process, making it extremely difficult to obtain high-quality data. This difficulty, combined with data incompleteness, significantly affects prediction accuracy. To address these challenges, this study introduces End of Life (EOL) and Equivalent Cycle Life (ECL) as supervised conditions for generative AI models. By integrating an embedding layer into the CVAE model, we developed the Refined Conditional Variational Autoencoder (RCVAE). Through preprocessing data into a quasi-video format, coupled with customized training and inference algorithms, the RCVAE generates the required charging data in real time based on the battery’s ECL and EOL. This avoids storing irrelevant information, saving space and resources. RCVAE uses a lightweight architecture, enabling fast generation of necessary voltage, current, temperature, and charging capacity data. This approach provides users with a comprehensive electrochemical dataset, pioneering a new research domain for the artificial synthesis of lithium battery data. Furthermore, based on the detailed synthetic data, various battery state indicators can be calculated, offering new perspectives and possibilities for lithium battery performance prediction.

Polymerized lignin based carbon nanofiber for high-performance energy generator and storage

Lignin is an ideal precursor for the preparation of lignin-based materials. However, the lack of molecular weight, thermal stability and spatial configuration of lignin hinder the practical application of lignin in lignin-based carbon materials. Herein, a novel and effective strategy for preparing high-performance lignin-based carbon nanofibers (CFs) is designed. Lignin samples with different chemical structures are prepared by polymerization modification and fractionation. This strategy completely gets rid of the dependence on petroleum-based polymers in the electrospinning process, and makes the lignin-based CFs show good performance in energy storage, temperature sensor, and moisture power generation. The specific capacitance and energy of lignin-based supercapacitors reach 357.2 F/g and 31.5 Wh/kg, respectively. The CFs exhibit good flame retardancy and thermal sensitivity, and the response time is 1 s. In addition, moisture power generators assembled with CFs exhibit great potential. The output voltage of moisture power generators has a linear relationship with the number of devices. With the increase of series equipment, the output voltage of 5 series moisture power generators is 4.7 V. This work provides a new approach to prepare high-performance lignin-based carbon nanofibers, which has a good application prospect in the fields of energy storage, sensing and power generation.

Conjunctive optimal operation of water and power networks

Water distribution systems (WDSs) are designed to convey water from sources to consumers. Their operation is a main concern for engineers, researchers, and practitioners and is subject to demand, pressure, and quality constraints. Pumping stations require power to pump water and keep system pressure at a desired level. On the other hand, power is generally supplied through power grids (PGs), which require optimal operation while satisfying operational constraints, such as generation limits, power consumption, and voltage constraints. Since the two infrastructure systems are interconnected, decision-makers could benefit from a holistic approach that would allow solving the two operational optimization problems together as one conjunctive problem. This paper presents the full mathematical formulation of the conjunctive optimization problem, including a novel modelling approach for the operation of a variable speed pump, which does not include integer variables for pump status, thus allowing to solve the model as a non-linear programming (NLP) problem. The formulation is applied to two illustrative case studies, and the results are compared to the optimal operation of the independent WDS. The inclusion of the PG in the optimization problem is observed clearly in the results and influences them quite significantly. WDS operation is shown adjust to the PG constraints, and the application of the conjunctive model results in a cost reduction rate of more than 10 % for both case studies.

Energy harvesting by car-tire using piezoelectric polymer films blended with carbon-nanotubes

Energy harvesting through harnessing mobile cars is possible by combining mechanicals systems with advanced materials. Piezoelectric polymer blends with excellent mechanical properties facilitate energy harvesting using the car-tire as a source. Furthermore, by adding simplicity of preparation to the blends with multi-walled carbon nanotubes (MWCNT), an increase of energy conversion can lead to improved existing polyvinylidene fluoride/polymethylmethacrylate (PVDF/PMMA), films. This work focuses on investigating the best concentration of MWCNT to achieve car-tire energy harvesting as a sustainable and renewable energy option. The results show that 0.05 wt% of MWCNT is the best concentration among several values. A test set-up applying normal stress, simulating car-tire deformation indicated enhanced voltage generation. Compared to the energy consumption of combustion cars, the enriched films generate up to 4.3kWh. This energy is harvested over a car trip of 100 km. A higher nanotube concentration caused saturation of the blend film and poor output. The novel enriched polymer must be tested for resisting cyclic loads to encourage sustainable energy harvesting using car tires.

Enhanced performance of cyclone separator through coupling of centrifugal force, electrostatic force and particle pre-charge

The electrostatic enhancement can effectively improve the performance of cyclone separator at low load or high-temperature, but its application is limited owing to the reduction of spark voltage in high-temperature. Aiming at this question, a new technology coupling centrifugal force, electrostatic force and particle pre-charge was proposed. The characteristics of particles charging and agglomeration were analyzed, and the influence of different factors on the change of particle partition number concentration and total removal efficiency of cyclone separator were studied. The results showed that, increasing the charge generator voltage and decreasing the main pipe gas velocity can increase the particles charge quantity and improve agglomeration, which is benefit for the efficiency improvement of either cyclone separator or electrostatic cyclone separator, especially at low inlet gas velocity. Higher charge generator voltage and lower inlet gas velocity, more obvious efficiency improvement. The total removal efficiency can be increased by up to 10 % and 9 % respectively for the cyclone separator and electrostatic cyclone separator because of particle pre-charge at 10 m/s of inlet gas velocity, and the removal efficiency of fine particles can also be effectively improved. Comparing with the electrostatic cyclone separator, achieving the same total removal efficiency, the internal voltage can be reduced 16 kV through particle pre-charge. The electrostatic force and centrifugal force were the main factor of the small particles and big particles removal, respectively.

Implementation Joule Thief Buck-Boost Converter in A Neodymium Wind Power Plant

Wind power generation is gaining popularity as an environmentally friendly renewable energy source. However, the output voltage of a wind generator usually varies according to the wind speed, requiring a power converter to produce a stable DC voltage. The author of this research aims to implement a Joule Thief Buck-Boost Converter on a neodymium wind power generation system. Joule Thief is a DC-DC converter that has the ability to convert a low input voltage into a higher output voltage, and can maintain a relatively stable output voltage despite changes in the input voltage. In this study, a Joule Thief buck-boost converter is used to regulate the output DC voltage of the neodymium wind generator to remain stable despite the changing wind speed. System testing is done by measuring the output voltage of the neodymium wind power plant. The test results show that the Joule Thief Buck-Boost Converter can maintain the output DC voltage at a stable value of 14V at input voltages above 3V, so the implementation of this converter in neodymium wind power plants is proven effective in producing a stable DC voltage. This research is expected to contribute to the development of a more efficient and reliable wind power generation system.

Quantum Rectification Based on Room Temperature Multidirectional Nonlinearity in Bi2Te3.

Recent interest in quantum nonlinearity has spurred the development of rectifiers for harvesting energy from ambient radiofrequency waves. However, these rectifiers face efficiency and bandwidth limitations at room temperature. We address these challenges by exploring Bi2Te3, a time-reversal symmetric topological quantum material. Bi2Te3 exhibits robust room temperature second-order voltage generation in both the longitudinal and transverse directions. We harness these coexisting nonlinearities to design a multidirectional quantum rectifier that can simultaneously extract energy from various components of an input signal. We demonstrate the efficacy of Bi2Te3-based rectifiers across a broad frequency range, spanning from existing Wi-Fi bands (2.45 GHz) to frequencies relevant to next-generation 5G technology (27.4 GHz). Our Bi2Te3-based rectifier surpasses previous limitations by achieving a high rectification efficiency and operational frequency, alongside a low operational threshold and broadband functionality. These findings enable practical topological quantum rectifiers for high-frequency electronics and energy conversion, advancing wireless energy harvesting for next-generation communication.

Experimental detection of mechanical deformations exploiting electromechanical effects

The present paper discusses experimental results concerning the deformation-induced generation of electric potential difference in steel specimens. According to our observations, voltages in the order of 10 microVolts can be measured between points on the surfaces of steel bodies during mechanical deformation. Three different experimental set-ups were used to determine the properties of the phenomenon, carefully excluding the influence of possible external electromagnetic fields. In order to exclude thermoelectric effects, a special steel specimen was fabricated. Further experimental campaigns were conducted with long, thin metallic rods in two different set-ups: the generation of voltage was measured during the traveling of longitudinal shock waves and during bending vibrations of the specimens. The results indicate that the variation of the magnetization of the material – the magnetoelastic effect – plays an important role in the phenomenon, but thermoelectricity also contributes to the measurable voltage signals. The electromechanical effect identified in the present paper may have several applications in measurement technology. The most relevant advantage of the applied measurement methods is that these are essentially sensor-free, since the mechanical vibrations can be detected by simply soldering, welding, or pressing copper wires to the examined steel specimen.

Hearing triboelectricity: home experiments

Abstract This study explores the demonstration of triboelectricity using everyday materials in a home experiment setting. By rubbing Teflon against metallic electrodes (aluminum and copper), we generated significant voltage due to Teflon’s strong electron acceptor properties. Aluminum exhibited higher voltage generation than copper, attributed to a greater electron affinity difference. To showcase practical applications, we successfully illuminated LEDs and powered a Bluetooth speaker, using the voltage generated from Teflon-metal interactions. This simple yet effective setup highlights the potential of triboelectric materials for sustainable energy harvesting and underscores the accessibility of home-based experiments in advancing scientific understanding.

The implementation of a cost‐efficient damped AC testing methodology for transmission cables based on DC–AC conversion and distributed partial discharge detection

AbstractThis research introduces a novel damped alternating current (DAC) testing methodology, which integrates an enhanced DAC generator with a pulse‐based distributed partial discharge (PD) detection technique. The advanced DAC generator is designed without the need for high voltage (HV) solid‐state switches, thereby offering a cost‐effective solution for field‐testing voltage generation through a direct current–alternating current conversion approach. To meet the demand for high instantaneous power, a capacitor bank is employed as the power supply. Furthermore, the implementation of a distributed PD detection technique enhances sensitivity and eliminates limitations associated with cable length. To minimize the construction costs of the distributed PD‐detection system, a pulse synchronization technique has been employed. Efforts to reduce the system's weight were informed by simulations, resulting in the design and development of a prototype weighing 850 kg for a 64/110 kV power cable. The reduction in the number of HV solid‐state switches contributes to significant cost savings, amounting to tens of thousands of dollars, when compared to conventional DAC generators. Laboratory and field tests validated the effectiveness of the cost‐efficient DAC testing methodology.

Elastomeric Sensor-Triboelectric Nanogenerator Coupled System for Multimodal Strain Sensing and Organic Vapor Detection.

Stretchable, flexible sensors are one of the most critical components of smart wearable electronics and Internet of Things (IoT), thereby attracting multipronged research interest in the last decades. Following miniaturization and multicomponent development of several sensors in one could further propel the demand for wireless, multimodal platforms. Greener substitutes to conventional sensors that can operate in a self-powered configuration are highly desirable in terms of all-in-one sensor utilities. However, fabrication of composite-based ultrastretchable, self-powered sensors with multifunctionality, robustness, and conformability is still only partially achieved and, therefore, demands further investigation. In this work, we report a triboelectric nanogenerator (TENG)-based multifunctional strain and organic vapor sensor using cross-linked ethylene propylene diene monomer (EPDM) elastomer and conducting carbon black as active fillers in the presence of an ionic liquid. The resulting piezoresistive sensor demonstrates ultrahigh gauge factor (GF > 220k) and wide range strain sensitivity and is, therefore, suitable for subtle-to-high frequency motion detection devices. Supported by excellent triboelectric outputs (force sensitivity 0.5 V/N in the range of 50-300 N, maximum output voltage VOC ∼ 178 V, short circuit current ISC ∼ 18 μA, maximum power density 0.11 mW/cm2), the hybrid sensors offer remarkable mechanical toughness and seamless voltage generation under contact-separation, even after several thousand cycles of operations. Furthermore, the sensor substrates exhibited reproducible organic vapor-sensing behavior, with high responsivity of 1.92 and 1 for ethanol and acetone, respectively, under flowing vapor conditions. This work lays a strong foundation for developing a truly multimodal, TENG-based, self-powered organic vapor and strain sensors.

An Energy‐Efficient Fully On‐Chip CMOS Temperature Sensor for Portable Applications With an RFoM of 2.79 pJ.K2

ABSTRACTThis article describes an energy‐efficient, low‐power CMOS temperature sensor suitable for portable applications. The sensor's front‐end circuitry is designed with a reference voltage (V), complementary to absolute temperature (CTAT) voltage (V), and ramp voltage generators. The ramp voltage (V) is produced by utilizing a current reference circuit. The ramp voltage is compared with independent and temperature‐dependent voltages to perform the voltage‐to‐frequency conversion. Conversion from frequency to digital output is achieved through an asynchronous counter with an on‐chip oscillator. The proposed design is realized in a 0.18‐m CMOS technology and attains a power usage of 604.4 nW at 27°C with an operating voltage of 0.5 V. Furthermore, it obtains an inaccuracy of +0.71/−0.73°C over −40°C to 125°C temperature range with an active area of 0.025 mm2. Moreover, the designed sensor circuit offers a resolution of 0.17°C with an energy conversion of 96.7 pJ.

Two-dimensional graphyne monolayers as substrate discs of piezoelectric nanogenerators: A hybrid atomistic-continuum model study

The different phases of α-, β-, and γ-graphyne, which are new types of two-dimensional carbon allotropes, hold promise as potential candidates for designing substrate discs in piezoelectric nanogenerators. Accurate modeling of the bending rigidity and stretching properties as well as resonance frequencies of these materials is crucial for engineering applications like nano-resonator and nanogenerator systems. This step is imperative in designing and advancing future applications involving these structures. This study aims to create a hybrid atomistic-continuum model for modeling graphyne monolayers used as substrate discs in nanogenerators. The model integrates the benefits of both atomistic and continuum approaches. Based on the results, α-graphyne is the least mechanically stable, while γ-graphyne is the most stable. However, in terms of vibration frequency, α-graphyne has the highest frequency while γ-graphyne has the lowest. Therefore, β-graphyne, with moderate stability and resonance frequency, is recommended as the ideal choice for the substrate disc in piezoelectric nanogenerators. It can function within the Q-F frequency range (30–140 GHz) and induce deformation in the piezoelectric shim as well as generation voltage.