Capacitor Charging Research Articles

Design of a Low-Power Dynamic Latched Comparator for Biomedical Applications

Abstract The latched comparator is a fundamental component of all ADC topologies. Thermal noise, kickback noise, and offset voltage impact the energy efficiency of the comparator significantly. In cardiac IMD ADCs, latched comparator kickback noise may impact resolution, accuracy, and settling time. This paper describes the design and development of an a low-power dynamic latched comparator optimised for biomedical applications and running at 1V. The suggested comparator is achieved on a 45 nm CMOS technology node, having the main goal of reducing kickback noise. The main concept of the recommended comparator has been utilizing the novel resetting approach and kickback noise reduction approach to preserve the charge and kickback noise, respectively. This approach aids in minimizing delay, power consumption, and kickback noise using shared charging logic. The charging-sharing technique involves using a single-pass transistor positioned across two output nodes. The pass transistor distributes the charge evenly across two output nodes throughout the reset phase. Due to the shared charging of the load capacitances, the voltage at the output nodes would not drop under the threshold value. As a result, the input signal could be evaluated more quickly during the regenerative stage. The comparator's delay is calculated using a rigorous statistical analysis considering the circuit's random factors. The offset of the proposed comparator is verified using thorough Monte Carlo simulations. The comparator reduces power while preserving noise. Also, the measured simulation results of recommended comparator outperform state-of-the-art comparators regarding kickback noise, delay, power consumption, and power delay product (PDP). The input voltage inversely affects the comparator's delay. Further, the simulation shows that the comparator consumes 9.36μW at 1 V and 1GHz sampling frequency. The simulation results confirm that the suggested comparator effectively reduces power consumption by atleast 66.98%. The proposed comparator has less PDP value by 44.44%. Also, suggested comparator effectively reduces offset voltage by 7.6% but with a corresponding increase in the area by 5%. Additionally, the comparator successfully reduces kickback noise by 44.6%. The obtained results are not silicon proven and bound to be in the pre-silicon stage. The low-power behaviour of the suggested technique is validated using analytical derivations, PVT corner analysis, and post-layout simulation.

Investigation of a fast gate driver based on a half-turn planar transformer.

This paper presents a magnetically isolated gate driver for the fast switching of IGBT (Insulated Gate Bipolar Transistor) in compact pulsed power sources with sharp rising edges and flat-top pulses for the application of electromagnetic launch and food processing. The proposed gate driver is implemented based on a planar transformer with a half-turn winding arrangement to increase the amplitude of the driving voltage pulse. With the half-turn winding arrangement, the leakage inductance of transformers decreases by 31.1% compared to the interleaving structure. This decrease enables a fast rise time of the driving voltage pulse. Furthermore, the gate drivers are used to drive the IGBT switching a Blumlein pulse forming network. The results show that the di/dt of the applied commercially available Si IGBT is about 10.10 A/ns with a gate voltage of 50V and a gate capacitance charging time of about 88ns, proving the effectiveness of the gate driver and providing a high-performance driving scheme for the fast switching of Si IGBT.

Biocompatible Triboelectric Nanogenerators for Self-Powered Microelectronics: Design, Performance, and Real-Time Applications.

In the present study, we demonstrated a cost-effective chia seed-based triboelectric nanogenerator (C-TENG), leveraging the triboelectric properties of chia seeds. The C-TENGs are fabricated with a simple architecture, establishing adaptability, cost effectiveness, and versatility as an ecofriendly harvester of mechanical energy. The C-TENG exhibits open- circuit voltage and short-circuit currents on the order of 501.8 V and 24.5 μA, respectively. Load matching reveals the maximum power density output at a load resistance of 5 MΩ, reaching 290 mW/m2. The cycle test over 3400 cycles confirms the C-TENG's stability. Furthermore, its capability to charge capacitors with different capacitances highlights its potential as a biomechanical energy harvester. The prototype device for evaluating the real-time applications demonstrated the C-TENG's, ability to illuminate LEDs, power a calculator, capture kinetic energy during walking, and transducer as an electronic switch. This investigation pioneered the exploration of chia seeds in TENGs, presenting a sustainable and efficient solution for self-powered microelectronic devices. The electron affinity of materials has been analyzed through inter- and intramolecular charge distribution using density functional theory. The direction of charge transfer was estimated through frontier molecular orbital analysis supported by the experimental findings of triboelectrification via contact separation from the molecule to polytetrafluoroethylene (PTFE).

Vector-Free Deep Tissue Targeting of DNA/RNA Therapeutics via Single Capacitive Discharge Conductivity-Clamped Gene Electrotransfer.

Viral vector and lipid nanoparticle based gene delivery have limitations around spatiotemporal control, transgene packaging size, and vector immune reactivity, compromising translation of nucleic acid (NA) therapeutics. In the emerging field of DNA and particularly RNA-based gene therapies, vector-free delivery platforms are identified as a key unmet need. Here, this work addresses these challenges through gene electrotransfer (GET) of "naked" polyanionic DNA/mRNA using a single needle form-factor which supports "electro-lens" based compression of the local electric field, and local control of tissue conductivity, enabling single capacitive discharge minimal charge gene delivery. Proof-of-concept studies for "single capacitive discharge conductivity-clamped gene electrotransfer" (SCD-CC-GET) deep tissue delivery of naked DNA and mRNA in the mouse hindlimb skeletal muscle achieve stable (>18 month) expression of luciferase reporter synthetic DNA, and mRNA encoding the reporter yield rapid onset (<3 h) high transient expression for several weeks. Delivery of DNAs encoding secreted alkaline phosphatase and Cal/09 influenza virus hemagglutinin antigen generate high systemic circulating recombinant protein levels and antibody titres. The findings support adoption of SCD-CC-GET for vaccines and immunotherapies, and extend the utility of this technology to meet the demand for efficient vector-free, precision, deep tissue delivery of NA therapeutics.

Enhancing power density in D-mode GaN HEMT direct-current triboelectric nanogenerators through ICP-etched surface engineering

In the evolving landscape of energy harvesting, the refinement of friction properties in metal-semiconductor direct current triboelectric nanogenerators (MSDC TENGs) has garnered significant attention. While prior research predominantly concentrated on achieving superior performance in MSDC TENGs through material manipulation, structural adjustments, and friction mode optimization, there has been a noticeable dearth of investigations into surface engineering or modification of semiconductor materials. In this paper, the surface patterning of depletion mode GaN-based high electron mobility transistor (D-GaN HEMT) as friction materials is done by inductively coupled plasma etching method, involving both mechanism analysis and experimental exploration. Through modulation of etching depth and pattern density, a systematically arranged diamond pattern is created on the surface, augmenting surface roughness and charge density. Consequently, the surface-patterned D-GaN HEMT TENG achieves a maximum short-circuit current of 60 µA and a peak power density of 4.05 W/m², which is about 2.8 times greater than the pristine D-GaN HEMT TENG. Furthermore, the power supply capabilities of the surface-patterned D-GaN HEMT TENG are scrutinized, revealing its proficiency in capacitive charging and discharging. The successful activation of a deep ultraviolet LED underscores its potential applications in ultraviolet disinfection. This research holds substantial significance in optimizing the power generation efficiency and performance of MSDC TENGs employing D-GaN HEMT.

A comparative study on exploring sputtered titanium nitride thin films for high-performance supercapacitors

Magnetron sputtered titanium nitride (TiN) thin films possessed desirable electrochemical and physical characteristics making them attractive candidates for supercapacitor electrodes. Herein, the electrochemical performance of TiN films prepared via direct and reactive sputtering methods is investigated as electrodes for supercapacitor. Microstructural analysis revealed distinct morphologies, topographies, and crystal structures for each film type, with reactively sputtered TiN (RS) displaying a pyramidal structure indicative of (111) orientation, whereas directly sputtered TiN (DS) exhibited a granular structure. Electrochemical techniques like cyclic voltammetry, galvanic charge-discharge, and electrochemical impedance spectroscopy clarified the charge storage mechanisms and capacitance behavior. RS exhibited a quasi-rectangular CV profile with pseudo-capacitive behavior with low charge transfer resistance and peak specific capacitance of 90 mF cm−2 along with superior cyclic stability and ion conductivity. Supercapattery configuration was setup to validate those findings using reactive sputtered thin films. It demonstrated enhanced capacitance retention and low charge transfer resistance, highlighting their potential for practical applications in energy storage systems.

Single electrode mode triboelectric nanogenerator for recognition of animal sounds

This research presents an innovative and sustainable solution by designing triboelectric nanogenerators (TENGs) for energy harvesting. The fabrication process of TENGs includes PDMS and aluminum. The two single electrode mode TENG was designed one is plain PDMS/Al and the other is porous PDMS/Al TENG devices. The porous PDMS/Al TENG device generated a voltage and current of 7 V and 5 nA for 2 cm ´ 2 cm device area. Moreover, the TENG system was employed to successfully charge capacitors, and recognize various animal sounds. This study underscores the promising potential of harvesting energy from body movements and powering of devices, paving the way for eco-friendly solutions to energy generation.

High-fidelity analysis and experiments of a wireless sensor node with a built-in supercapacitor powered by piezoelectric vibration energy harvesting

A supercapacitor or an electric double layer capacitor (EDLC) is an essential component of a high-performance wireless sensor node (WSN) that can transmit the three-axis acceleration waveform data of structural vibrations and is powered by a piezoelectric vibration energy harvester (VEH). However, the intrinsically slow charging rate of the piezoelectric VEH triggers charging of extra capacitors formed inside the complex-shaped electrodes of the supercapacitor, which complicates the charging/discharging characteristics and thus estimation of the power generation and energy storage in the supercapacitor. Therefore, in this work, we establish an analytical methodology that allows accurate prediction of the charging/discharging characteristics of the supercapacitor built into the WSN powered by the piezoelectric VEH, considering (1) the nonlinear piezoelectricity, (2) a three-branch circuit model of the supercapacitor, and (3) the current–voltage relation equation for the diode. We develop a parameter identification technique for both the nonlinear piezoelectric VEH and the supercapacitor, and then establish a coupled analysis technique based on the differential algebraic equation (DAE). Using the DAE, we investigate the charging/discharging characteristics of the supercapacitor by considering the actual working steps of the WSN. We revealed that the second branch in the three-branch model contributes not only to an increase in the effective capacitance of the supercapacitor, but also to faster recovery of the voltage across the supercapacitor during WSN operation. We also revealed that a longer charging time led to more energy being stored in the capacitor in the third branch, from which it is difficult to extract energy within a short time period such as the WSN’s transmission process due to its long time constant. The contribution of the second and third branches must be considered to enable accurate prediction of the charging/discharging characteristics of the supercapacitor when built into the WSN powered by the piezoelectric VEH.

Performance Measurement of Peltier Element Design using Solar Test Simulator Concerning Light and Temperature Parameters

This study investigates the application of Peltier element technology for testing solar panels under varying environmental conditions, focusing on light intensity and temperature. A solar test simulator was used to design and implement the Peltier elements and the circuit was simplified by calculating the capacitor charging factor. This simplification aligns with the specific characteristics of the solar panels and offers a cost-effective approach to equipment development while delivering optimal results. The design, which incorporates surface temperature regulation via Peltier elements at adjustable distances, allows for the accurate simulation of varying light and temperature conditions on the surface of the tested solar panels. The voltage applied to the Peltier element directly influences the temperature it produces, measured in real-time during controlled temperature variation experiments. These measurements were conducted under three simulated sunlight conditions, allowing for detailed observation of the instantaneous voltage changes in the cooling element. The study created a Solar Test Simulator prototype designed for solar panel testing. The results demonstrate that the Peltier element-based system effectively controls temperature variations and accurately reflects the real-world performance of solar panels under diverse environmental conditions. The temperature measurements, taken across two solar panels with varying specifications, validate the effectiveness of this approach, making it a valuable tool for solar panel testing and optimization.

Molybdenum Induced Modifications in the Quantum Capacitance of Graphene‐Based Supercapacitor Electrodes: First‐Principle Calculations

Herein, spin‐polarized calculation is performed based on density‐functional theory in the frame of generalized gradient approximation to examine the quantum capacitance (CQ) and surface charge storage of graphene(G)‐based supercapacitor electrodes modified with molybdenum, sulfur, nitrogen, and monovacancy. In total, 15 electrode models, including graphitic doping, monovacancy doping, and Mo adsorption on pristine and single‐vacancy graphene structures are analyzed. In the results, it is demonstrated that vacancy defects and N/S/Mo doping enhances the CQ of graphene. Among all configurations, pyrrolic‐S (d1S) shows the lowest CQ performance due to few states at the Fermi level. Electrodes with Mo adsorption exhibit the highest CQ, particularly when Mo is adsorbed at the top site of graphene. However, formation and adsorption energy calculations suggest that Mo is more likely to adsorb at hollow sites. Optimally, Mo can be most effectively utilized by loading it onto vacancy or N/S‐decorated vacancy sites. The significant contribution of Mo's 4dz2 and 4s states to CQ, along with the charge‐redistribution around the Mo complexes, may facilitate proton‐coupled electron transfer to enhance pseudocapacitance. In these findings, valuable insights into designing high quantum capacitance of 2D materials with electroactive sites for improved energy storage are offered.

Tracking Water Dissociation on RuO2(110) Using Atomic Force Microscopy and First-Principles Simulations.

The interaction between interfacial water and transition metal oxides is a primary enabling step for the oxygen evolution reaction (OER). RuO2 is a prototypical OER electrocatalyst whose ability to activate interfacial water molecules is essential to its OER activity. We image the dissociation of surface water into OH* and O* on RuO2(110), where * denotes adsorbed species, using atomic force microscopy. Starting from the surface-bound water molecules, which form a one-dimensional network along the rows of Ru surface sites, increasing the oxidative potential strips hydrogen away and transforms the water molecules into OH* and O*. This oxidative step changes the pattern of the adsorbates from one- to two-dimensional. First-principles calculations with interfacial polarization, capacitive charging, and adsorbate interactions attribute this evolution to the cooperative dehydrogenation of adsorbed water and OH* on RuO2. We use these results to map the surface phase diagram of RuO2(110) and provide a quantitative interpretation of its cyclic voltammetry. Our result provides the visualization of the water dissociation on a conductive oxide surface, a critical step in the OER, and demonstrates that the water activation is a collective phenomenon at RuO2(110) electrodes.

Analysis of Galvanostatic Data from Electrochemical Capacitors

The ability to deconvolute charge storage mechanisms in electrochemical capacitor materials and systems is essential for understanding and improving behaviour. From an electrochemical perspective, this deconvolution can be achieved through an understanding of the expected response of a particular contribution. Voltametric measurements can be deconvoluted through the current response relative to the applied sweep rate. Herein we describe an analogous approach for galvanostatic data in which the charge or discharge time is related to the applied current (I). Specifically, capacitive charge storage is shown proportional to I−1, while diffusional processes are proportional to I2. Coupling this with a constant contribution from ohmic and residual charge storage processes allows for an effective approach to deconvolution for galvanostatic data. This is demonstrated with data from a glassy carbon electrode in non-aqueous electrolyte (an expected electrical double layer system) and from a manganese dioxide electrode in aqueous electrolyte (an expected pseudo-capacitive system).

Research on Techniques for Enhancing the Speed of Low-Power Operational Amplifier

In the context of low utilization, this paper explores various techniques for enhancing the speed of operational amplifier (OA). The main text delves into three methods to gain equilibrium: fully differential operational amplifier (FDA), twostage operational transconductance amplifier (OTA), and a novel high-speed calculation system architecture employing a “rhombus crystal tube.” The FDA improves speed by minimizing noise and enhancing bandwidth and output voltage swing, without increasing power consumption. The design of the two-stage OTA combines the characteristics of a differential amplifier and a telescopic amplifier, optimizing gain and slew rate through Miller compensation and noise gain manipulation, thereby achieving high-speed performance. A novel high-speed operational amplifier structure employs diamond transistors to supply substantial current for capacitor charging, enhancing the slew rate and overall speed. Throughout the text, these methods are presented as a means to jointly promote high speed, low power consumption, and the handling of a significant number of transistors. To further increase the speed, the size of the microcrystalline tube is crucial. The research direction is outlined, and while the design equipment is in the foreground, there remains room for progress, especially in applications for large-scale electrical models. Future research aims to enhance the power efficiency of circuits, making them more practical and efficient. This study provides valuable insights into balancing power consumption and speed in advanced electronic devices.

Triboelectric nanogenerator based on silane-coupled LTA/PDMS for physiological monitoring and biomechanical energy harvesting

Energy harvesting from ambient sources present in the environment is essential to replace traditional energy sources. These strategies can diversify the energy sources, reduce maintenance, lower costs, and provide near-perpetual operation of the devices. In this work, a triboelectric nanogenerator (TENG) based on silane-coupled Linde type A/polydimethylsiloxane (LTA/PDMS) is developed for harsh environmental conditions. The silane-coupled LTA/PDMS-based TENG can produce a high output power density of 42.6 µW/cm2 at a load resistance of 10 MΩ and operates at an open-circuit voltage of 120 V and a short-circuit current of 15 µA under a damping frequency of 14 Hz. Furthermore, the device shows ultra-robust and stable cyclic repeatability for more than 30 k cycles. The fabricated TENG is used for the physiological monitoring and charging of commercial capacitors to drive low-power electronic devices. Hence, these results suggest that the silane-coupled LTA/PDMS approach can be used to fabricate ultra-robust TENGs for harsh environmental conditions and also provides an effective path toward wearable self-powered microelectronic devices.

The design of a model predictive control strategy and performance analysis for pumped storage units and super capacitors in power systems

IntroductionSuper capacitors were regarded as one of the most effective frequency regulation technologies in power systems. The major issue of applying super capacitors for frequency regulation is the limited energy capacity and the high construction costs. The pumped storage units have been developed and applied in power systems for decades, whereas it was rarely operated to regulate the system frequency due to the operation limitations. The pumped storage units could be operated as a hydro generator under the generation mode and provide effective frequency regulation service with the conventional automatic generation control (AGC) system while its output power was constant under the pumping mode.MethodIn this paper, the pumped storage unit was controlled to participate in frequency regulation under the generation mode with super capacitors. Considering the AGC system could not consider the state of charging (SOC) of super capacitors for frequency regulation, an optimization model was proposed to determine the operation points for super capacitors and pumped storage units under a model predictive control (MPC) strategy to regulate the system frequency for power systems.Results and DiscussionBased on the various operation scenarios, the effectiveness and costs of pumped storage units and super capacitors to provide frequency regulation services were discussed. It was indicated that pumped storage units and super capacitors were effective technologies for power systems.

Photoelectrochemical and Structural Insights of Electrodeposited CeO2 Photoanodes

Cerium dioxide (CeO2) is a promising material for photoelectrochemical applications, requiring a thorough understanding of the interplay between its properties and structure for optimal performance. This study investigated the photoelectrochemical performance of CeO2 photoanodes immobilized by electrodeposition on glass substrates, focusing on the correlation between the annealing temperature and structural, optical, and electrical changes. CeO2 coatings were obtained via chronoamperometry in an aqueous solution of 25 mM CeCl3 and 50 mM NaNO₃. The photoelectrochemical characterization included the evaluation of photoactivity, current density, stability, and recombination using linear sweep voltammetry (LSV) and chronoamperometry (CA). Charge transfer resistance, flat-band potential, and capacitance were assessed through impedance spectroscopy. The optimal annealing temperature for this material was found to be 600 °C as it resulted in the lowest charge transfer resistance and increased photocurrent, which was attributed to enhanced crystallinity and variations in the Ce3+/Ce4+ ratio.

Deep Neutral Network Enhanced Mesoscopic Thermodynamic Model for Unlocking the Electrode/Electrolyte Interface

Structure and properties of the electrode/electrolyte interface significantly influence the electrochemical processes of energy storage and conversion, yet the challenge lies in accurate description of both molecular characteristics and external field effects. Here, we develop a mesoscopic thermodynamic model that calculates the thermodynamic properties of electrolytes based on chemical potential, and its efficiency is enhanced by a deep neutral network. The deep neutral network enhanced mesoscopic thermodynamic (DeepMT) model effectively bridges the gap between micro‐level characteristics of ions and macro‐level effects of external field, enabling precise presentation of ion density distributions over complex conditions. Our result indicates that the DeepMT model not only demonstrates a computational efficiency improvement of approximately four orders of magnitude over direct theoretical calculations, but also accurately predicts interface properties including ion adsorption, surface charge, and differential capacitance through the statistical analysis of density distributions.

Deep Neural Network Enhanced Mesoscopic Thermodynamic Model for Unlocking the Electrode/Electrolyte Interface.

Structure and properties of the electrode/electrolyte interface significantly influence the electrochemical processes of energy storage and conversion, yet the challenge lies in accurate description of both molecular characteristics and external field effects. Here, we develop a mesoscopic thermodynamic model that calculates the thermodynamic properties of electrolytes based on chemical potential, and its efficiency is enhanced by a deep neural network. The deep neural network enhanced mesoscopic thermodynamic (DeepMT) model effectively bridges the gap between micro-level characteristics of ions and macro-level effects of external field, enabling precise presentation of ion density distributions over complex conditions. Our result indicates that the DeepMT model not only demonstrates a computational efficiency improvement of approximately four orders of magnitude over direct theoretical calculations, but also accurately predicts interface properties including ion adsorption, surface charge, and differential capacitance through the statistical analysis of density distributions.

V2O5-MnO2 nanocomposites as an efficient electrode material for high-performance aqueous supercapacitors

Redox-active supercapacitors are very interesting due to their high energy density (>25 Wh kg−1 at device level) and redox charge storage mechanism. In this work, V2O5-MnO2 nanocomposites are synthesized by a scalable hydrothermal approach. MnO2 in V2O5 provides better structural stability with reasonable electrochemical performance, in which V2O5 enhances the cyclic stability and rate capabilities. The V2O5-MnO2 -based electrodes deliver a specific capacitance of 266 F g−1 at 0.5 A g−1 and are stable up to 6500 cycles with 97 % capacitance retention at 5 A g−1. The kinetic study depicts that composite electrodes have a 64 % diffusive and 36 % capacitive charge storage contribution to the overall charge storage at 1 mV s−1. In symmetric full cells, the composite materials show a wide active potential window of 2.5 V and retain 83 % capacitance after 10000 continuous GCD cycles at an applied current density of 2 A g−1. The promising charge storage performance is due to a suitable conducting matrix and the effective coating of MnO2 nanoparticles over the unique V2O5 niddle shape (two-dimensional) micro-rods.

Multifactorial Analysis of the Effect of Applied Gamma-Polyglutamic Acid on Soil Infiltration Characteristics

To investigate the mechanism and influence of applying gamma-polyglutamic acid (γ-PGA) on soil water infiltration, laboratory experiments and numerical simulations were conducted using Hydrus-1D. These studies assessed the impact of various application rates of γ-PGA on soil water characteristic parameters. Orthogonal simulation experiments on soil bulk density, γ-PGA application rates, and burial depths were performed utilizing predefined soil water characteristic values (twelve groups: nine groups of numerical simulation experiments and three groups of laboratory verification tests), and the soil infiltration characteristics were analyzed. Concurrently, an empirical model was developed to elucidate the relationships between the empirical model parameters and influencing factors, as well as to examine the sensitivity of these factors to changes in soil infiltration rate. The relationship between cumulative infiltration and the distance of wetting front movement, based on the water balance equation, was refined. The results indicated that γ-PGA significantly affected soil water characteristic parameters, where the saturated water content and the reciprocal of soil intake suction increased with rising γ-PGA applications (p &lt; 0.01), while the saturated hydraulic conductivity and the parameter n decreased (p &lt; 0.01), with no notable changes in the retained water content (p &gt; 0.05). The trend in cumulative infiltration influenced by various factors could be modeled by a capacitive charging model function, which yielded a superior fit. A negative correlation existed between the sensitivity index and all the influencing factors (p &lt; 0.05), with the order of influence being soil bulk density, γ-PGA application rate, and γ-PGA burial depth, respectively. Utilizing the modified water balance equation, the ratio of cumulative infiltration to wetting front migration distance corresponded more closely with a power function. These findings provide a theoretical foundation for further studies on the effects of γ-PGA on crop growth characteristics in fields and the optimization of γ-PGA technical element combinations.