Electrostatic Principle Research Articles

A novel design of a MEMS resonant accelerometer with adjustable sensitivity

This paper presents the design and experimental evaluation of a silicon micro-machined resonant accelerometer featuring adjustable sensitivity. By integrating an electrostatic tuning module into the fundamental accelerometer structure, dynamic sensitivity adjustment becomes feasible, leveraging the softening effect of electrostatic negative stiffness to optimize range, noise, and bandwidth. Notably, the electrostatic tuning module integrates seamlessly with the core accelerometer structure, minimizing structural alterations. Through theoretical analysis and finite element simulation of the electrostatic negative stiffness principle, we have designed a novel accelerometer with adjustable sensitivity, which can enhance the sensitivity and reduces the bias-instability of the accelerometer with a relatively small adjustment voltage, without increasing structural complexity. The performance of the accelerometer was assessed through open-loop, closed-loop, and dynamic experiments, revealing that sensitivity increased from 843 Hz/g to 2611 Hz/g within a linear range of ±1 g when employing a sensitivity-enhancing bias voltage of 9 V. Moreover, the bias-instability is lowered down from 17.3 μg to 6.8 μg. This design offers a promising avenue for sensitivity tuning in MEMS resonant accelerometers.

Hierarchical polypyrrole@MXene (Ti3C2TX) fiber strain sensors for wearable healthcare electronics

Flexible sensors are an important component of wearable medical electronics and hold considerable promise for research. Presently, stretchable strain sensors face two primary challenges: balancing the sensing range with sensitivity, and ensuring compatibility between conductivity and mechanical properties. Here, flexible sensing fibers with high gauge factor (GF) and wide monitoring range are reported based on a hierarchical structure composed of electrostatic adsorption principle and hydrogen bonding interactions. The hierarchical structure material consists of thermoplastic polyurethane (TPU), MXene, polypyrrole (PPy) and waterborne polyurethane (WPU). Among them, MXene (2D) and PPy (3D) are uniformly distributed on the surface of the MXene/TPU fiber (1D) to form a conductive and sensing pathway. This multi-dimensional combination approach enables the fiber sensor to have a high sensing range (0 ∼ 106 %) and high sensitivity (60 ∼ 3.23 × 106). In addition, the WPU acts as a protective layer, which not only reduces the damage to the sensing layer, but also improves the stretchability (>750 %) and modulus (∼12 MPa) of the sensor. Therefore, it can function as fiber sensor for monitoring not only human movement but also swelling in the legs of patients with varicose veins. The sensor also has a joule heating effect, as well as the potential to be integrated into fabrics, providing an important case for the construction of multifunctional flexible wearable medical electronics with practical applications.

Force-displacement measurement system with electromagnetic and electrostatic force compensation principles

Zusammenfassung Der Artikel präsentiert eine modifizierte Version des Kraft-Weg-Messgeräts, das zur Kalibrierung der Steifigkeiten von MEMS und Cantilevern sowie der von ihnen erzeugten Kräfte im Bereich von 10 nN bis 2mN verwendet wird. Weiterhin werden verbesserte Ergebnisse für die Kalibrierung von Kraftkonstanten und der Steifigkeit weicher Cantilever (Kraft bis 300 nN) mit einer erweiterten relativen Unsicherheit von 0,46 % gezeigt.

DESIGN OF RICE HUSK ROTARY DRYER USING WASTE HEAT ELECTROSTATIC PRECIPITATOR OF THE CEMENT INDUSTRY

ESP or electrostatic precipitator is a device used to capture particulate matter, such as dust, in exhaust gases using electrostatic principles. In the cement industry, ESP is commonly placed after the clinker cooler to clean the exhaust air from the cooling process, ensuring it is free from clinker dust. The clinker cooler is a device that cools down the clinker using air, reducing its temperature from an initial temperature of around 1450°C to approximately 100°C - 120°C. The exhaust air from the clinker cooler is then passed through the ESP at temperatures ranging from around 237°C to 311°C. Based on the temperature data, the exhaust air from the ESP has the potential for heat reuse for other processes, including as a heat source for drying rice husk, which is a common alternative fuel used in the cement industry and typically has a moisture content of around 25%-37%. The results of this design indicate that the exhaust heat from the ESP, with an input temperature of 275°C, is capable of drying rice straw pellets from a moisture content of 25% to 14.73% using a designed rotary dryer with a capacity of 21.6 t/h, a length of 41.58 m, and a diameter of 2.92 m. It is constructed using ASTM 283 C material with a thickness of 8.76 mm and is insulated with a 15.6 mm thick layer of aluminum foil.

Optimization of agricultural broken film cleaning device based on electrostatic adsorption principle

Optimization of agricultural broken film cleaning device based on electrostatic adsorption principle

Single-Electrode Electrostatic Repulsion Phenomenon for Remote Actuation and Manipulation.

One of the fundamental principles of electrostatics is that an uncharged object will be attracted to a charged object through electrostatic induction as the two approaches one another. We refer to the charged object as a single electrode and examine the scenario where a positive voltage is applied. Because of electrostatic induction phenomenon, single-electrode electrostatics only generates electrostatic attraction forces. Here, we discover that single-electrode electrostatics can generate electrostatic repulsion forces and define this new phenomenon as single-electrode electrostatic repulsion phenomenon. We investigate the fundamental electrostatic phenomena, giving a curve of electrostatic force versus voltage and then defining 3 regions. Remote actuation and manipulation are essential technologies that are of enormous concern, with tweezers playing an important role. Various tweezers designed on the basis of external fields of optics, acoustics, and magnetism can be used for remote actuation and manipulation, but some inherent drawbacks still exist. Tweezers would benefit greatly from our discovery in electrostatics. On the basis of this discovery, we propose the concept of electrostatic tweezers, which can achieve noncontact and remote actuation and manipulation. Experimental characterizations and successful applications in metamaterials, robots, and manipulating objects demonstrated that electrostatic tweezers can produce large deformation rates (>6,000%), fast actuation (>100 Hz), and remote manipulating distance (~15 cm) and have the advantages of simple device structure, easy control, lightweight, no dielectric breakdown, and low cost. Our work may deepen people's understanding of single-electrode electrostatics and opens new opportunities for remote actuation and manipulation.

Enhancing Dust Removal Efficiency in Electrostatic Precipitators with Homogeneous Flow

This paper aims to improve the efficiency of uniform flow electrostatic collector. First, the principle of electrostatic dust removal technology, including electrostatic dust removal principle and an overview of uniform flow electrostatic dust collector. Then, methods to improve dust removal efficiency by analyzing the relationship between dust removal efficiency and operating parameters. These include electric field design optimization, dust removal plate optimization, and airflow distribution control. Then, the factors affecting the efficiency of dust removal are analyzed, including the particle characteristics and the gas characteristics. Finally, the electric field optimization design based on numerical simulation and the airflow distribution optimization design based on CFD simulation are presented. Through theoretical simulation and optimization design, the dust removal efficiency of uniform flow electrostatic dust collector can be improved and the dust removal effect can be further optimized.

Ring-Rod Detection Array for Gas–Solid Flow Pattern Based on Electrostatic Induction Principle

The sensitivity matrix of a ring electrostatic sensor array for gas-solid flow pattern detection presents a significant decrease and poor uniformity at the center of the pipe. To improve the uniformity of the sensitivity matrix, a ring-rod electrostatic array sensor is proposed. Firstly, the structure of the ring-rod array sensor is proposed, with the influence of the number of ring-rod electrodes in the array on the average and uniformity error of sensitivity being analyzed. Secondly, the ring-rod array and ring array in gas-solid flow detection were both simulated, and the influencing factors on their performances were studied. Finally, an experimental platform was setup to evaluate their performance for detecting gas-solid flow patterns under different conditions. Results show that the sensitivity matrix of the ring-rod array electrostatic sensor is more uniform, with its sensitivity error being small, and it shows better potential for detecting the gas-solid flow patterns.

Preparation and Characterization of Conductive Hydrogel Electrode Films of Nano Platinum/Multi-Walled Carbon Nanotubes/Polyvinyl Alcohol

Nano platinum were prepared on multi-walled carbon nanotubes/polyvinyl alcohol conducting hydrogel electrode film by electrostatic adsorption principle and mild in-situ reduction. The microstructure, conductivity, electrochemical performance and electrocatalytic activity of PtNPs/MWCNTs/PVA conducting hydrogel electrode film were studied. And the selective catalytic ability of the electrode film to glucose in oxygen-rich PBS solution, and the relationship between the selective catalytic ability and the preparation technology of the electrode film was analyzed.

Study on the mechanism of removing Pb (II) and Cd (II) from industrial wastewater by copper based MOF modified with ethylenediamine

In this study, we synthesized ethylenediamine modified copper-based organometallic framework by hydrothermal method. The materials were characterized by SEM, XRD, FTIR, XPS and BET. The adsorption properties of the materials for Cu (II) and Pb (II) were studied in depth by varying the adsorbate concentration, ionic strength, contact time, adsorption temperature and pH of the solutions. At a pH value of 5.2, the maximum adsorption capacities for Cd (II) and Pb (II) were 909.09 and 12.85 mg·g−1 within 20 min, respectively. The adsorption process was fitted with pseudo second order kinetics and Langmuir isotherm model. Thermodynamic experiments showed that an appropriate temperature reduction was helpful to promote Cd (II) and Pb (II) removal. Given that the underlying chemical properties of the materials are unknown, the factors leading to affecting the selectivity of heavy metals remain unclear. To reveal key molecular level factors, we performed state-of-the-art computational simulations combining high-density functional theory (DFT), semi empirical calculations, and configurational sampling of metal ion MOF binding modes in aqueous solution. And the intermolecular interactions, absorption patterns, and most remarkable structural features were determined to improve the selectivity against heavy metals. The mechanism of heavy metals separation by ethylenediamine grafted MOFs was rationalized using quantum mechanical and electrostatic principles. Density functional theory calculations showed that the chelating effect of amino groups, ion-exchange effect and electrostatic interaction of hydroxyl groups were the main factors to improve the removal efficiency of Cd (II) and Pb (II). These results provide a new method for the preparation of MOF based adsorbents and demonstrate the great potential of ethylenediamine modified copper based metal organic frameworks for high-performance environmental remediation.

Development of a Ni–Al reactive force field for Ni-based superalloy: revealing electrostatic effects on mechanical deformation

The physics-informed expression of interatomic potentials is critical to driving accurate molecular dynamics (MD) simulations while most alloy potentials neglect the electrostatic effects explicitly despite the existence of local charge non-neutrality in multi-component alloys. The Ni–Al ReaxFF force field (dubbed ReaxFFNiAl-S22), implementing charge equilibration scheme for explicit electrostatic interactions, was developed in this work for Ni-based superalloy via parametrization based on density functional theory (DFT) calculations. The ReaxFFNiAl-S22 described well the equation of states of Ni and Ni3Al across various polymorphous structures and defects, improving overall accuracy in comparison with several other reported potentials including ReaxFF and Embedded Atom Method (EAM) potentials. Moreover, the short-range repulsion (inner wall) terms implemented in ReaxFFNiAl-S22 extended the capability of describing highly compressed crystal structures. The new potential was applied in the tensile MD simulations of Ni, Al, and Ni/Ni3Al interface models. The obtained strain–stress relationship and the evolution of dislocations are critical to understanding the dynamics of plastic deformation and fracture of alloys. The charge redistribution was particularly examined during the tensile process of Ni3Al, revealing the important role of electrostatic interactions during the mechanical deformation of alloys that are often overlooked before. This work demonstrates that the reactive force field can be used to study the mechanism of mechanical deformation with electrostatic effects. The proposed electrostatic design principle suggests that alloying elements with large electronegativity and strong covalency would benefit electrostatic contribution to the strength of alloys.

PH dynamics regulates transcription factor-DNA binding.

Intracellular pH (pHi) dynamics regulates myriad cell behaviors, and we previously identified pH-sensitive proteins regulating cell migration, cytoskeleton and adhesion remodeling, and transformation through pH-dependent effects on protein-protein and protein-phospholipid binding. Whether pH regulates protein-nucleotide binding for established effects of pHi dynamics on gene expression, however, remains unknown. We identified at least 65 transcription factors in diverse families that have a conserved histidine, which in available structures forms hydrogen bonds with DNA nucleotides. With the ability of histidine to titrate in the cellular pH range, electrostatic principles of protein-nucleotide hydrogen bonds, we predicted that transcription factors with histidine-nucleotide hydrogen bonds could have pH regulated DNA binding selectivity. All FOX family transcription factors contain a conserved histidine in their DNA-binding domain (DBD) that in available structures forms hydrogen bonds with nucleotides. We confirmed pH regulates DNA binding of FOXM1 and FOXC2 DBDs using fluorescence anisotropy and a canonical FkhP DNA motif for binding to a thymine, with higher affinity at pH 7 compared with 7.5. This finding is consistent with thymine being a hydrogen bond acceptor and binding a protonated histidine. We confirmed the significance of histidine with a mutant FOXC2-His122K, with lysine mimicking a protonated residue, that had high affinity but pH-independent binding and a mutant FOXC2-H122N recurring in cancers that had low affinity pH-independent binding. We also confirmed pHi regulates FOXC2 activity in cells. Using MDA-MB-436 cancer cells with a high pHi of 7.7 and a luciferase assay we found increased transcriptional activity for an FkhP motif when pHi was lowered to 7.4 with EIPA, an inhibitor of the proton-extruding NHE1. Our data identify pH dynamics as a previously unrecognized regulator of DNA-binding selectivity for FOXM1 and FOXC2 with broad significance for transcription factors in diverse families with conserved histidines in the DBD.

Local Electric Fields: From Enzyme Catalysis to Synthetic Catalyst Design.

This Mini-Review Article outlines recent advances in the study of local electric field (LEF) governed enzyme catalysis and the application of the LEF principle in synthetic catalyst design. We start by discussing the electrostatics principles that drive enzyme catalysis, and its experimental verifications through vibrational Stark spectroscopy. Subsequently, we describe aspects of LEFs other than catalysis, i.e., induction of mechanistic crossovers, among others. Here, we focus on the early work done using computational tools, along with some recent contributions. Following an in-depth discussion of the role of LEFs in enzyme catalysis, we then highlight some recent works on designed local electric fields (D-LEF) and their applications in organic synthesis. Subsequently, we turn to D-LEFs in synthetic enzymes and supramolecular systems (cf. the work by the Head-Gordon group). We end by discussing some of the software packages that have been developed to analyze local electric fields computationally. Overall, the present Mini-Review Article paints an insightful picture of the current state of the art using LEF in enzyme catalysis and its application for further bioengineering and synthetic organic frameworks in a broad perspective.

Development and initial testing of an active low-power, ferroelectric film-based bioaerosol sampler.

This article introduces REAS (Rutgers Electrostatic Active Sampler), a new active bioaerosol sampler using permanently polarized ferroelectric film (e.g., PVDF) to capture charge-carrying bioaerosol particles. While REAS operates on an electrostatic collection principle, due to its unique materials and design, it does not require external power to charge incoming particles or to create an electrostatic collection field. The sampler consists of a polarized film wound in a spiral configuration with oppositely polarized film sides positioned 2.25 mm apart. The film and its holder are inserted into a 3D-printed housing cylinder to connect to a pump. The device has an open channel design, creating virtually no pressure drop, which allows for longer sampling times on the same battery charge compared to filter samplers. When REAS was tested in different field environments, the physical collection efficiency ranged from 19 ± 2% in a laboratory environment at 1 L/min to 41 ± 0.1% in residence at 0.1 L/min. When REAS was used to capture culturable bacteria and fungi over a 24-hr period, the concentrations determined by REAS were not different from those determined by an Institute of Medicine sampler (IOM, SKC, Inc.). The concentrations determined by both samplers were lower than those measured by a SAS Super 180 Sampler (SAS, Bioscience International), except for outdoor fungi. However, the SAS was used as a grab sampler to avoid overloading or desiccating the plates, while both REAS and IOM continuously sampled for 24 hrs. Further studies will explore improvements to the REAS sample elution protocols.

A New Device for Reducing Air Pollution Using Principles of Electrostatics and Aerodynamics

A New Device for Reducing Air Pollution Using Principles of Electrostatics and Aerodynamics

Silver-nanowire/bamboo-charcoal composite percolation network on nylon sheet for improved PM2.5 capture efficiency

Particulate matter (PM) pollution is a significant threat to the environment and public health, necessitating the development of efficient, easy-to-use, versatile protection and treatment devices. Herein, we rationally design a novel reusable composite filter for the high-efficiency capture of indoor fine PM with a particle diameter of <2 µm (PM2.5). The use of such filters is important for ensuring safe indoor environments. This study elucidates the manufacturing of filters based on electrostatic and adsorption principles using a silver-nanowire/bamboo-charcoal composite material to enhance PM elimination. The filter comprised silver nanowires with an 8 mg/mL concentration and bamboo charcoal with a 0.1% w/v concentration, dipped in nylon sheet for nine cycles and annealed at 120 °C for 15 min; the filter exhibited a minimum sheet resistance of 4.1 Ω/sq. Silver-nanowire/bamboo-charcoal composite percolation network filters use strong long-range electrostatic forces and adsorption to capture PM2.5, work in an active mode, and exhibit high efficiency (>99.9%), low power consumption, and reusability after simple washing. The proposed PM filter can be applied in environmental applications.

Molecular-level understanding of highly selective heavy rare earth element uptake by organophosphorus modified MIL-101(Cr)

Selective separation of rare earth elements (REEs) from solutions of mixed heavy and light metals by solid adsorbents is an important challenge in the fields of water treatment and metal recovery. The main challenge is water instability of many adsorbents, specifically metal–organic frameworks (MOFs), and their low selectivity. Grafting particular organophosphorus compounds (OPCs) on the MIL-101(Cr) MOF can provide both stability and selectivity. When the tributyl phosphate (TBP), bis(2-ethylhexyl) hydrogen phosphate (D2EHPA or HDEHP) and bis(2,4,4-trimethylpentyl)phosphinicacid (Cyanex®-272) OPCs are grafted and applied to mixed-metal aqueous solutions containing Co2+, Ni2+, Cu2+, Zn2+, Nd3+, Gd3+ and Er3+, MIL-101(Cr) offers high selectivity towards the Nd3+, Gd3+ and Er3+ REEs (with stronger affinity towards Er3+). However, the underlying chemistry is unknown and the factors leading to the selectivity remain poorly understood. To uncover the key molecular-level factors, we performed state-of-the-art computational simulations using a combination of high-level density functional theory (DFT), semi-empirical calculations, and configurational sampling of the metal ion-MOF binding modes in aqueous solutions. Our simulation study reproduced the available experimental results, in addition to determining the contributing intermolecular interactions, uptake modes and the most significant structural features for improving selectivity towards the REEs. Therefore, our most important result is rationalization of the mechanism of REE separation by OPC-grafted MOFs using quantum mechanical and electrostatic principles. The results provide guidelines for synthesis of OPC-grafted MIL-101(Cr) structures with enhanced selectivity and stability. Moreover, an efficient computational framework is proposed to facilitate comprehensive modeling of similar systems.

Collective amplification of nearby nanoparticles in the Coulomb blockade restricted charging of a single nanoparticle

The characterization of charges in oxide supported metal nanoparticles (NP) is of high interest in research fields like heterogeneous catalysis and microelectronics. A general desire is to manipulate the charge of an oxide supported single NP and to characterize afterwards the charge and its interference with the insulating support but also with nearby NPs in the vicinity. By using noncontact AFM (nc-AFM) and Kelvin probe force microscopy (KPFM) in ultra-high vacuum and at room temperature we show that a ∼5 nm small AuNP can be directly charged with electrons by the AFM tip and that upon the charging, nearby AuNPs sensitively change their electrostatic potential with a large impact on the charge detection by nc-AFM and KPFM. The AuNPs are supported on a 40 nm thick insulating Al2O3 film, which is grown by atomic layer deposition on Si(001). Due to Coulomb blockades, the NP charging appears in the form of large and discrete peaks in detuning versus bias voltage curves. Finite element method calculations reveal that the large peaks can only be observed when the potentials of nearby insulated NPs get modified by the NP’s electron charge, according to the electrostatic induction principle. In view of the number of transferred electrons, we anticipate that after the charging, the electrons are transferred from the AuNP to the NP-Al2O3 interface or into Al2O3 subsurface regions directly underneath.

Engineering of Fe-pnictide heterointerfaces by electrostatic principles

Interface-related phenomena have great potential to control the superconducting state in Fe-based superconductors. We propose a comprehensive classification of Fe-pnictide heterointerfaces based on electrostatic principles that allow the prediction of the interface microstructure, in particular, distinguishing between clean heterointerfaces and the formation of interfacial layers. The concept was successfully tested on a novel LnOFeAs/BaFe2As2 (Ln = La, Sm) Fe-pnictide heterostructure. With the addition of different cations/anions, it is possible to produce clean interfaces or interfacial layers. The impact of the microstructure on superconductivity in the Fe-pnictide heterostructures is discussed.

An upconversion nanosensor for rapid and sensitive detection of tetracycline in food based on magnetic-field-assisted separation

Tetracycline, a broad-spectrum antibiotic, has been widely used in disease treatment and other fields. However, due to the unreasonable use, its residue remains in food which eventually harms human health. Here described an upconversion nanosensor for tetracycline detection based on magnetic separation and electrostatic adsorption. To identify tetracycline, tetracycline aptamer, and europium ions (Eu3+) were introduced in the system. According to the electrostatic adsorption principle, Eu3+ exposed core–shell UCNPs were bound to negative complex of magnetic nanoparticles (MNPs) and aptamer. In the presence of tetracycline, UCNPs separated with MNPs-aptamer and remained in the supernatant by an external magnetic field. Under optimal conditions, the linear detection range of tetracycline was 0.5–1000 ng·mL−1, and the detection limit was 0.17 ng·mL−1. It has been successfully applied to detect tetracycline in food samples. The constructed method provided broad prospects for tetracycline detection with the merits of simple operation, high sensitivity, excellent repeatability, and selectivity.