Electrical Input Research Articles

Antibacterial coating of corona treated Poly(lactic acid) / Poly(butylene succinate) film with Chitosan and Zinc oxide nanoparticle

The biodegradable PLA/PBS 90/10 wt% films were extruded and surface treated with corona discharge. Two electrical inputs of the corona treatment were used, 2 or 6 amperes, which the change of the surface tension was evaluated using corona measuring pens. The blend films were coated with the antibacterial mixture between chitosan and zinc oxide nanoparticles (ZnO-NP) in four concentrations: 1.0/0.4, 1.0/0.5, 1.5/0.5, and 1.5/0.5 wt%/wt%. This film could be used to replace transparent disposable packaging in the circular economy. It was found that the surface tension of the blend film was 30 dyne (mN/m) which was much like the neat PLA due to PLA being the main composition. Since the overall coated film thickness was kept constant, there was no significant difference in the coating weight among four coating concentrations. Compared to the uncoated PLA/PBS film, the tensile strength of the coated films tended to be higher with the increase of ZnO-NP content. However, the elongation at break of the coated films decreased significantly, which the stiffer coating layers became the stress concentrators. From SEM, it was seen that the good adhesion between the polymer and the coating layer was achieved. When the coated films were torn apart in the trouser tear testing, the failure was the breakage of the blend film with there was some coating layer delaminated.

Modulating the electronic structure of CoS2 by Sn doping boosting urea oxidation for efficient alkaline hydrogen production

Urea electrocatalytic oxidation afforded by renewable energies is highly promising to replace the sluggish oxygen evolution reaction in water splitting for hydrogen production while realizing the treatment of urea-rich waste water. Therefore, the development of efficient and cost-effective catalysts for water splitting assisted by urea is highly desirable. Herein, Sn-doped CoS2 electrocatalysts were reported with the engineered electronic structure and the formation of Co-Sn dual active sites for urea oxidation reaction (UOR) and hydrogen evolution reaction (HER), respectively. Consequently, the number of active sites and the intrinsic activity were enhanced simultaneously and the resultant electrodes exhibited outstanding electrocatalytic activity with a very low potential of 1.301 V at 10 mA·cm−2 for UOR and an overpotential of 132 mV at 10 mA·cm−2 for HER. Therefore, a two-electrode device was assembled by employing Sn(2)-CoS2/CC and Sn(5)-CoS2/CC and the constructed cell required only 1.45 V to approach a current density of 10 mA·cm−2 along with good durability for at least 95 h assisted by urea. More importantly, the assembled electrolyzer can be powered by commercial dry battery to generate numerous gas bubbles on the surface of the electrodes, demonstrating the high potential of the as-fabricated electrodes for applications in hydrogen production and pollutant treatment at a low-voltage electrical energy input.

“Casein micelle -nanoparticle double cross-linking” triggered stable adhesive, tough CA/MWCNT/PAAm hydrogel wearable strain sensors, for human motion monitoring

Flexible hydrogels have emerged as highly-desirable materials for wearable strain sensors. However, pristine biomass hydrogel systems are limited by their lack of stretchability, self-adhesion, and sensitivity. Here, a novel CA/MWCNT/PAAm double-network conductive hydrogel was developed through integrating casein (CA) micelles and multi-walled carbon nanotubes (MWCNT) into the polyacrylamide (PAAm) network. The resulting hydrogel displayed desired properties such as adhesiveness, toughness, self-healing, and near-infrared photothermal response. In this hybrid system, MWCNT were uniformly dispersed in the presence of casein micelles through hydrogen bonding and electrostatic interactions, favoring its role of nano reinforcement. Moreover, based on the “casein micelle-nanoparticle double cross-linking" mechanism and its double network structure, the prepared hydrogel showed high extensibility (2288 % ± 63 %), fast responsiveness (273 ± 5.13 ms), high sensitivity (GF = 12.46 ± 0.35), and a wide strain range (1–1000 %). Through consistent and repeated electrical inputs, this hydrogel was able to detect including large and small human movements, such as hand, leg, and swallowing motions. The results from this study provide a new way to fabricate bio-based hydrogel sensors with excellent mechanical and electrical properties.

Cooling Capacity Characteristics of Low Power Consumption （2 kW Class） 4 K-GM Cryocoolers

From the COP （Coefficient of Performance） equation, there are two ways to improve the cooling efficiency of cryocoolers: （1） increasing the cooling capacity, and （2） decreasing the electrical input power. In recent years, we have focused on the possibility of method （2） for a 4 K-GM （Gifford-McMahon） cryocooler. In this paper, a 7 kW class compressor, which is commonly connected to a 4 K-GM cold head, was replaced with a low power consumption （2 kW class） compressor. The experiments achieved a measured cooling capacity of 0.95 W at 4.2 K with a cold head reciprocation speed of 36 rpm and a compressor electrical input of 1.9 kW. The calculated COP and the relative Carnot efficiency were 5.0×10-4 and 3.5 %, respectively. A low reciprocating speed was selected to secure sufficient expansion work in the second expansion space. This is an effective method to improve the cooling capacity at 4.2 K by a low power consumption compressor.

Scalable Colored Subambient Radiative Coolers Based on a Polymer-Tamm Photonic Structure.

Daytime radiative coolers cool objects below the air temperature without any electricity input, while most of them are limited by a silvery or whitish appearance. Colored daytime radiative coolers (CDRCs) with diverse colors, scalable manufacture, and subambient cooling have not been achieved. We introduce a polymer-Tamm photonic structure to enable a high infrared emittance and an engineered absorbed solar irradiance, governed by the quality factor (Q-factor). We theoretically determine the theoretical thresholds for subambient cooling through yellow, magenta, and cyan CDRCs. We experimentally fabricate and observe a temperature drop of 2.6-8.8 °C on average during the daytime and 4.0-4.4 °C during the nighttime. Furthermore, we demonstrate a scalable-manufactured magenta CDRC with a width of 60 cm and a length of 500 cm by a roll-to-roll deposition technique. This work provides guidelines for large-scale CDRCs and offers unprecedented opportunities for potential applications with energy-saving, aesthetic, and visual comfort demands.

Optoelectronic Synaptic Memtransistor Based on 2D SnSe/MoS2 van der Waals Heterostructure under UV-Ozone Treatment.

Memristive switching devices with electrically and optically invoked synaptic behaviors show great promise in constructing an artificial biological visual system. Through rational design and integration, 2D materials and their van der Waals (vdW) heterostructures can be applied to realize multifunctional optoelectronic devices. Here, a multifunctional optoelectronic synaptic memtransistor based on a SnSe/MoS2 vdW p-n heterojunction to simulate the human biological visual system is reported. By employing simple mild UV-ozone treatment, the device exhibits reversible resistive switching (RS) behavior with switching ratio up to 103 . The retina-like selective response to different input light wavelengths is activated, as well as programmable multilevel resistance states and long-term synaptic plasticity. Moreover, memory and logic functions analogous to those found in the visual cortex of the brain are performed by controlling the optical and electrical input signals. This work proposes a feasible strategy to modulate RS in vdW heterostructures for memristive devices, which show significant potential for neuromorphic processing.

A flexible organic mechanoluminophore device

A flexible mechanoluminophore device that is capable of converting mechanical energy into visualizable patterns through light-emission holds great promise in many applications, such as human-machine interfaces, Internet of Things, wearables, etc. However, the development has been very nascent, and more importantly, existing mechanoluminophore materials or devices emit light that cannot be discernible under ambient light, in particular with slight applied force or deformation. Here we report the development of a low-cost flexible organic mechanoluminophore device, which is constructed based on the multi-layered integration of a high-efficiency, high-contrast top-emitting organic light-emitting device and a piezoelectric generator on a thin polymer substrate. The device is rationalized based on a high-performance top-emitting organic light-emitting device design and maximized piezoelectric generator output through a bending stress optimization and have demonstrated that it is discernible under an ambient illumination as high as 3000 lux. A flexible multifunctional anti-counterfeiting device is further developed by integrating patterned electro-responsive and photo-responsive organic emitters onto the flexible organic mechanoluminophore device, capable of converting mechanical, electrical, and/or optical inputs into light emission and patterned displays.

Sound Quality Improvement of Dynamic Loudspeaker by Material Selection of Diaphragm

In terms of sound quality, mechanical stability, and cost, the moving coil speaker is exceptional to the moving iron and electrostatic speaker. The diaphragm in the speaker is crucial in reproducing the sound wave from the electrical signal input. The materials of the diaphragm should be both rigid and lightweight. However, there are few quantitative studies on the selection of diaphragm materials. Connecting the equation of mass and the deflection of a circular plate yields a performance index that maximizes Young’s Modulus and minimizes the density. A line graph in logarithmic can be generated from the index to select materials from various categories in the Ashby plot provided by the Granta CES Edupack software. The chosen materials would be simulated in COMSOL and their sound pressure level plots would be analyzed based on the numerical solution. The Ashby plot and the numerical solutions by COMSOL have indicated that paper is the best material among the selected materials with the most stable frequency response in the mid-range frequency range, a high-performance index, and a low price per unit volume.

Depression of electro-oxidation of Ti3C2Tx MXene Joule heater by alternating current for Joule heating membrane distillation

Membrane distillation (MD) is a promising technology with great potential to mitigate the crisis of water shortage. However, it still suffers from the low productivity due to that water vaporization on the membrane would reduce the transmembrane temperature and hence the permeate flux. Herein, an electrothermal membrane that can heat the feed solution on the membrane and hence enables the MD operation under a low electrical input was developed. This was achieved by coating a commercial PET-PTFE membrane with MXene nanosheets through a filtration method. The resultant MXene/PET-PTFE composite membrane could heat the surroundings (both air and brine) efficiently, showing a conversion efficiency of 73% at 1 W. Furthermore, it was shown that the composite membrane, while degrades rapidly in highly ionizable brine under a direct current (d.c.) input, could work stably over a long duration at high potential under high-frequency alternating current (a.c.) input. Systematic electrochemical impedance spectroscopic investigation suggested that the reciprocal vibration of ions under a high-frequency a.c. could inhibit the formation of electrical double layer, and thus depresses the electrochemical oxidation of MXene and water splitting. Furthermore, the composite membrane enabled efficient in-situ heating in a Joule heating MD (JHMD) system, delivering a permeate flux of 1.8 kg m−2h−1 at an input power of 3 W, which is 333% higher than that based on the conventional MD process. Theoretical simulation of the temperature distribution by a finite element method (FEM) confirmed a higher transmembrane temperature in the JHMD system than in the conventional MD, which is responsible for the performance enhancement.

A transformative strategy to realize hydrogen production with electricity output through ultra-low potential furfural oxidation on hollow PdCu alloy networks

It is of sustainable prominence for building an electrocatalytic system to generate hydrogen (H2) with low energy consumption. Herein, interconnected hollow PdCu alloy networks (H-PdCu ANs) are fabricated via Kirkendall-effect during the cyanogel-reduction procedure. The H-PdCu ANs catalyze furfural oxidation at ultralow potential (0.1 VRHE), and facilitate hydrogen atom releasing from the aldehyde groups, eventually harvesting H2. Likewise, the typical catalyst exhibits superior oxygen reduction activity with a positive onset potential of 1.0 VRHE and half-wave potential of 0.88 VRHE. Density functional theory calculations are carried out to illustrate the reaction mechanisms. Subtle integration of the two half-reactions, the catalyst-assembled electrocatalytic system concurrently generate H2 (5 mmol A−1 g−1 h−1), high value-added furoic acid (93.3% of Faraday efficiency) and electricity (16.2 mW cm−2), overturning conventional H2 generation system with electricity input. This work provides transformative insights into developing bifunctional electrocatalysts to synchronously realize H2 generation, biomass upgrading and power output.

Self-Sensing Variable Stiffness Actuation of Shape Memory Coil by an Inferential Soft Sensor.

Self-sensing actuation of shape memory alloy (SMA) means to sense both mechanical and thermal properties/variables through the measurement of any internally changing electrical property such as resistance/inductance/capacitance/phase/frequency of an actuating material under actuation. The main contribution of this paper is to obtain the stiffness from the measurement of electrical resistance of a shape memory coil during variable stiffness actuation thereby, simulating its self-sensing characteristics by developing a Support Vector Machine (SVM) regression and nonlinear regression model. Experimental evaluation of the stiffness of a passive biased shape memory coil (SMC) in antagonistic connection, for different electrical (like activation current, excitation frequency, and duty cycle) and mechanical input conditions (for example, the operating condition pre-stress) is done in terms of change in electrical resistance through the measurement of the instantaneous value. The stiffness is then calculated from force and displacement, while by this scheme it is sensed from the electrical resistance. To fulfill the deficiency of a dedicated physical stiffness sensor, self-sensing stiffness by a Soft Sensor (equivalently SVM) is a boon for variable stiffness actuation. A simple and well-proven voltage division method is used for indirect stiffness sensing; wherein, voltages across the shape memory coil and series resistance provide the electrical resistance. The predicted stiffness of SVM matches well with the experimental stiffness and this is validated by evaluating the performances such as root mean squared error (RMSE), the goodness of fit and correlation coefficient. This self-sensing variable stiffness actuation (SSVSA) provides several advantages in applications of SMA: sensor-less systems, miniaturized systems, simplified control systems and possible stiffness feedback control.

An in-silico proof-of-concept of electrohydrodynamic air amplifier for low-energy airflow generation

Electrohydrodynamic (EHD) technology generates airflow without moving parts, making it a reliable solution for various low-energy applications. EHD-based airflow devices enhance airflow patterns, resulting in significant energy savings in air-moving systems. This airflow, also known as ionic wind, is created through Corona discharge, which accelerates electrically charged air molecules in a strong electric field. Currently, EHD's low electrical-to-mechanical energy conversion rate still limit its ability to generate large flow rates. The objective of this study is to enhance the flow rate of EHD-based devices, for applications where EHD can be used as an effective auxiliary technology with low pressure lift, to enhance airflow distribution and circulation. To this end, a novel bladeless air propulsion device is proposed that combines ionic wind with air amplification based on the Coanda phenomenon to amplify EHD-generated flow rates. We assess the performance of the bladeless air propulsion device to generate airflow by investigating fluid dynamics, electrostatics, and energy consumption. We demonstrate the proof-of-concept with an innovative fully-coupled simulation approach for corona discharge and EHD modeling. We explore different design parameters on the conceptual EHD air amplifier, such as the electric potential (10–30 kV) of the discharge electrode, the electrode spacing (5–25 mm), and the channel height (30–150 mm). The studies are performed on a 2D constrained channel flow and a 2D-axisymmetric open space design, respectively. In order to quantify the benefit of air amplification on EHD, the results are benchmarked to a regular EHD setup without amplifying vane as well as to a comparable commercial axial fan. We assess the performance in terms of flow rate per electric power input. Here, the EHD air amplifier in the constrained flow configuration increases the total flow rate by 59% compared to regular EHD and 48% compared to the axial fan for the same electrical energy input. Amplification factors of 16.5–19 are achieved for the constrained configuration and 5.5 to 6.4 for the open space configuration. The predicted energy consumption is 4–17.5 W for the open space configuration, resulting in flow rates up to 140 m3 h−1. These results show that EHD air amplification is a promising way to generate high flow rates with low pressure rise at a low electrical cost, by which it can provide a more sustainable alternative to conventional fans in specific applications..

Comparative Study of Three SAW Configurations for Temperature Sensing

This paper demonstrates three SAW configurations' electrical and mechanical behaviors: a one-port resonator, a two-port resonator, and a delay line that works as temperature sensors of around 440 MHz characteristic frequencies. We investigate the sensitivity of the sensors for temperatures up to 200 °C. A linear behavior of the frequency shift versus temperature is observed; the resulting sensitivity of the sensors is evaluated at 22.74 ppm/°C for the one-port resonator, 23.17 for the two-port resonator, and 3.83 ns/°C for the delay line structure. The electromechanical coupling coefficient (k2) is 0.492 % for the delay line, 0.489 % for the one-port resonator, and 0.55% for the two-port resonator. The quality factor QFactor calculated from Y11 electrical input admittance is 2858 for the one-port resonator, 2977 for the delay line, and 2903 for the two-port resonator. The optimized piezoelectric layer thickness value, for the one port resonator, is hAlN=1.5µm.

Modelling analysis of a solar-driven thermochemical energy storage unit combined with heat recovery

Solar-driven thermochemical energy storage (TCES) can address the mismatch between solar heat production and heating demand and contribute to decarbonisation in buildings. In many studies of typical salt hydrate TCES systems, massive heat carried by the discharged humid airflow during the charging phase is not well-utilised but directly dissipated to the ambient. Therefore, a solar photovoltaic/thermal-powered TCES system integrating a heat exchanger (PV/T-TCES-HEX system) is proposed in this study for recovering this part of heat. To study the effect of adding the PV/T collector and heat exchanger (HEX) on the performance of the TCES system, the thermal performance of the PV/T-TCES-HEX system is compared with other two TCES systems via COMSOL modelling. Results suggest that the PV/T-TCES-HEX system requires an additional external electricity input of 11.86 kWh on a typical summer day in Nottingham, which is only 40.53% of the TCES-only system. The overall thermal efficiency of the PV/T-TCES-HEX system is 56.00%, indicating an efficiency enhancement of 146.80%. A lower mass flow rate leads to higher thermal efficiency and storage energy. The system has the highest overall thermal efficiency when the reactor bed thickness is 0.04 m (57.55%) and when the reactor bed length is 0.5 m (58.73%).

Innovative elektrochemische Strategien für die Wasserstoffproduktion: Von der Stromspeicherung bis zur Stromerzeugung

AbstractDie erneuerbare H2‐Produktion durch Wasserelektrolyse hat aufgrund ihrer zahlreichen Vorteile viel Aufmerksamkeit auf sich gezogen. Der Energieverbrauch der herkömmlichen Wasserelektrolyse ist jedoch hoch und wird hauptsächlich durch die kinetisch träge anodische Sauerstoffentwicklungsreaktion bestimmt. Ein alternativer Ansatz ist die Kopplung verschiedener Halbzellenreaktionen und die Verwendung von Redox‐Mediatoren. In diesem Übersichtsartikel fassen wir daher die neuesten Erkenntnisse über innovative elektrochemische Strategien zur H2‐Produktion zusammen. Zunächst gehen wir auf die bei der Wasserspaltung verwendeten Redox‐Mediatoren ein, einschließlich löslicher und unlöslicher Spezies, sowie auf die entsprechenden Zellkonzepte. Zweitens erörtern wir alternative anodische Reaktionen mit organischen und anorganischen chemischen Umwandlungen. Dann wird die elektrochemische H2‐Produktion sowohl an der Kathode als auch an der Anode und sogar die H2‐Produktion unter Stromerzeugung vorgestellt. Abschließend werden die bestehenden Herausforderungen und Möglichkeiten für die künftige Entwicklung dieses Forschungsgebiets hervorgehoben.

Innovative Electrochemical Strategies for Hydrogen Production: From Electricity Input to Electricity Output.

Renewable H2 production by water electrolysis has attracted much attention due to its numerous advantages. However, the energy consumption of conventional water electrolysis is high and mainly driven by the kinetically inert anodic oxygen evolution reaction. An alternative approach is the coupling of different half-cell reactions and the use of redox mediators. In this review, we, therefore, summarize the latest findings on innovative electrochemical strategies for H2 production. First, we address redox mediators utilized in water splitting, including soluble and insoluble species, and the corresponding cell concepts. Second, we discuss alternative anodic reactions involving organic and inorganic chemical transformations. Then, electrochemical H2 production at both the cathode and anode, or even H2 production together with electricity generation, is presented. Finally, the remaining challenges and prospects for the future development of this research field are highlighted.

Biomass gasification to syngas in thermal water vapor arc discharge plasma

This study investigated biomass (wood pellets) gasification to syngas using direct current (DC) thermal arc plasma at atmospheric pressure. Water vapor was used as a main gasifying agent and a plasma-forming gas. The biomass gasification system was quantified in terms of the producer gas composition, the tar content, the H2/CO ratio, the carbon conversion efficiency, the energy conversion efficiency and the specific energy requirements. It was found that the gasification performance efficiency was highest at the water vapor-to-biomass ratio of 0.97. The producer gas was mostly composed of H2 (43.86 vol.%) and CO (30.93 vol.%), giving the H2/CO ratio of 1.42 and the LHV of 10.23 MJ/Nm3. However, high content of tars of 13.81 g/Nm3 was obtained in the syngas. The yield of H2 and CO was 48.31% and 58.13%, respectively, with the highest producer gas yield of 2.42 Nm3/kg biomass. The carbon conversion efficiency and the energy conversion efficiency were 100% and 48.83%, respectively, and the production of 1 kg of syngas required 1.78 kWh of electric energy input. Finally, the obtained results were compared with different plasma methods, including plasma-assisted application coupled with conventional gasification.

Improvement of Piglet Rearing’s Energy Efficiency and Sustainability Using Air-to-Air Heat Exchangers—A Two-Year Case Study

Pig farming in mechanically ventilated barns requires much electricity for ventilation or exhaust air purification. Furthermore, thermal energy is needed to fulfill the animals’ temperature requirements, especially in piglet rearing. Electrical and thermal energy input leads to CO2 emissions and operating costs. Up to 90% of heat losses are due to the exhausted air. Heat exchangers can recover thermal energy from the warm exhaust air and transfer it to the cold fresh air. This study aimed to investigate energy consumption, efficiency, CO2 emissions, and energy costs when using heat exchangers in a German piglet rearing barn under practical conditions in combination with exhaust air purification. The following parameters were obtained for a two-year period: air temperatures, air flow rates, and electricity and liquefied natural gas consumption; the latter were used to calculate CO2 emissions and energy costs. In total, 576,042 kWhel,th and 616,893 kWhel,th (years 1 and 2) of energy were provided, including 290,414 kWhth and 317,913 kWhth of thermal energy recovered. Using heat exchangers reduced CO2 emissions by up to 37.5% and energy costs by up to 19.7% per year. The study shows that piglet rearing can increase its ecological and environmental sustainability by using heat recovery.

Optimizing hydrogen production capacity and day ahead market bidding for a wind farm in Texas

Producing green hydrogen from wind energy is one potential method to mitigate curtailment. This study develops a general approach to examine the economic benefit of adding hydrogen production capacity through water electrolysis along with the fuel cell and storage facilities in a wind farm in north Texas. The study also investigates different day ahead market bidding strategies in the existence of these technologies. The results show that adding hydrogen capacity to the wind farm is profitable when hydrogen price is greater than $3.58/kg, and that the optimal day ahead market bidding strategy changes as hydrogen price changes. The results also suggest that both the addition of a fuel cell to reconvert stored hydrogen to electricity and the addition of a battery to smooth the electricity input to the electrolyzer are suboptimal for the system in the case of this study. The profit of a particular bidding scenario is most sensitive to the selling price of hydrogen, and then the input parameters of the electrolyzer. This study also provides policy implications by investigating the impact of different policy schemes on the optimal hydrogen production level.

An audio-tactile interface based on dielectric elastomer actuators

This paper presents a concept of a dielectric elastomer actuator (DEA) user interface (smart button) that can sense a user’s touch and provide multi-sensory tactile and acoustic feedbacks through a single electrical input signal. The DEA relies on a multi-layer layout, in which a layer detects user-driven deformations (touches) via custom-built capacitance sensing electronics, and the remaining layers are used to provide actuation (audio-tactile feedbacks). Building upon a recently presented principle, combined tactile and acoustic feedbacks are produced by concurrently exciting different vibration modes of the same active membrane over different frequency ranges. An integrated demonstrator setup is presented, which includes a DEA, an acoustic enclosure, compact sensing and driving electronics. A characterization of the prototype is conducted, including an analysis of the sound pressure level, the force/stroke output at lower working frequencies, the ability to sense deformations with different profiles and produce combined audio-tactile outputs. Compared to previous works on multi-function DEAs, the system presented in this paper provides largely improved sensing performance (with lower working voltage) and features a deeper level of integration (with small-scale custom sensing electronics, and logics embedded onto scalable microcontrollers) and is thus specifically optimised for user-interaction applications. On this end, tests with users are presented here for the first time, which allowed evaluating the subjective perception of the interface’s feedbacks. By means of further optimisation and miniaturisation of the power/sensing electronics and structural components, the layout and multifunction DEA principle presented here might lead, in the future, to the development of DEA-based smart buttons for active surfaces, or portable/wearable user interfaces and communicators.