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Pesticides play an indispensable role in agricultural production; however, conventional pesticides generally suffer from a low foliar deposition rate and poor adhesion, resulting in the actual effective dosage reaching the target pests and diseases being <0.1%. In this study, a sol-gel synthesized from polyethylene glycol as a precursor was added to an emulsifiable concentrate, and the polyhydroxy property of the sol-gel was used as an intermediate to load the pesticide to bind onto the cuticle of crop leaves to enhance its adhesion and penetration on the crop foliage. The results showed that the emulsifiable concentrate after the addition of sol-gel had a more compact structure with a regular hexagonal microstructure, that the contact angle with the leaves was reduced by 5.6–7 at different concentrations, that the adhesion performance of pesticides was increased by 26%, that the residual amount on the leaves within 72 h was significantly increased, and that the larvae of pests died at a faster rate, with a 40% increase in mortality. Therefore, sol-gel has great potential for application in improving pesticide utilization and pest control. [Display omitted] • First application of sol-gel polymers beyond extraction. • More regular microstructure after mixing pesticides with sol-gel polymers. • 26% increase in mevalonate adhesion performance with sol-gel polymers. • Sol-gel polymers increased the insecticidal efficiency of pesticides by 40%. [ABSTRACT FROM AUTHOR]

Abstract SnSb alloy is a promising anode material for lithium-ion batteries due to its high specific capacity. However, the large volume change in the process of charge/discharge causes significant pulverizing of SnSb alloy particles, which leads to a rapid capacity fading. This paper reports the synthesis of homogenous SnSb nanoparticles that are embedded in N-doped porous carbon nanofibers through electrospinning technique with LiN 3 serving as poregen agent. This distinctive structure prevents the direct contact of SnSb nanoparticles with the electrolyte and provides enough space for the volume change of SnSb alloy during the Li+ insertion/extraction process, enabling this material to deliver a high reversible capacity of 892 mA h g−1 after 100th cycle at 100 mA g−1, and a stable capacity of 487 mA h g−1 after 1000 cycles at 2000 mA g−1. These results highlight the importance of the synergistic effect of SnSb alloy nanoparticles and N-doped porous carbon nanofibers for the high performance of lithium-ion batteries. Highlights • N-doped porous carbon nanofibers were prepared by electrospinning and calcination. • Lithium azide functions as a porogen reagent to generate porous structures. • A capacity of 892 mA h g−1 can be maintained after 100 cycles at 100 mA g−1 for the anode material. [ABSTRACT FROM AUTHOR]

The deep reactive ion etching (DRIE) process is commonly used for fabricating the MEMS resonators, which sometimes causes the profile of the resonator capacitor inclined. This nonideal feature significantly affects the motion stability of the resonator. In present work, for different inclination angles, the reliable operation conditions of the MEMS disk resonator for step inertial signal and pulse inertial signal are analyzed using the energy method. The dependence of the critical inertial acceleration on inclination angle and testing signal level is given both in expressions and curves. The results show that for a step inertial signal, the reliable operation range of the resonator with an inclination angle of 0.1° is larger than that of 0.25° by a factor of 2.32 for the same testing signal level, and for a pulse inertial signal, the factor is 2.29. With the increase of the inclination angle, the motion stability of the resonators becomes more and more enhanced. This results can provide a theoretical basis for the design of MEMS disk resonator working in the dynamic inertial environment. [ABSTRACT FROM AUTHOR]

This paper is the follow-up of the research we conduct to improve the self-calibration precision of high-precision MEMS capacitive accelerometers. In the previous published study, we have analyzed the influence of DRIE fabrication error on the dynamic self-calibration. In this paper, the influence of fringe effect on the self-calibration is discussed in order to improve the self-calibration precision further more, and the results has proved the feasibility of this self-calibration technique. Aimed at the capacitive accelerometer in this paper, the self-calibration error is only 0.18 % in closed-loop circuit, which is approach to the absolute calibration error of laser interferometer (0.5-1 %), which can satisfy the demand of high-precision sensors. In open-loop circuit, the fringe effect influences the self-calibration obviously and the error reaches 24.2 %, but it can be reduced to 1.49 % by correcting the actuation voltage. The method proposed in this paper may be used to develop full-automatic self-calibration system integrated on circuit board in the future. [ABSTRACT FROM AUTHOR]

A novel MEMS (Micro Electronic Mechanical System) capacitive accelerometer is presented, which is mainly composed of supporting beam, seismic mass, grid strip capacitances, comb capacitances and electrostatic driver. The damping of grid strip capacitances with variable overlapping area is mainly affected by the slide film air damping, which is small and neglectful, and the damping between comb capacitor is squeeze film air damping. The comb sensing gap can be reduced by electrostatic actuators by which the aspect ratio can reach to 75:1 which greatly depress the limitation of DRIE (Deep reactive ion etching) process on high aspect ratio, and the initial sensing capacitance increases from 2.97 pf to 14.87 pf. The squeeze film damping is reduced from 0.046 Nm/s to 0.0015 Nm/s by designing the comb-shaped grooves on the fixed comb electrodes. The comb initial sensing gap is optimized according to formation factors of system noise, and the noise is reduced from 1.395 μg/√HZ to 0.591 μg/√HZ. The simulation results show that the accelerometer sensitivity achieves 8.40 pf/g, which is two times of the conventional devices. [ABSTRACT FROM AUTHOR]

In this paper, the Reynolds equation of air damping of MEMS wine-glass resonator is solved by numerical calculation method considering the air slip boundary conditions. The corresponding pressure distribution between internal gaps is obtained by MATLAB software. And then size effects of resonator on air damping and quality factor are analyzed. It is found that MEMS disk radius and thickness have slight effects on the change of the pressure distribution. But the effects of spacing between disk body and electrodes are very significant. The designed ratio value of disk amplitude and spacing should not be over 70%, otherwise the changes of air pressure between gaps will be very remarkable and increased exponentially, the air damping will begin to increase doubly, and the quality factor will be reduced greatly. The analyzed results are very meaningful for optimizing design size of MEMS disk resonator. [ABSTRACT FROM AUTHOR]

For a super high precision MEMS sensor with the comb capacitor structure, the fringe effect of capacitors can not be neglected. In this paper, directing at the comb capacitor structure with slot holes, the effects of the non-overlap parts of comb capacitor, the distance between two slot holes in comb electrodes and slot depth aspect ratio on sensing capacitance are simulated by 3D finite element method of ANSOFT Maxwell software. The results show that when the width H and thickness t of sensing electrode plate are fixed, the fringe effect becomes larger for a smaller length L. The fringe effect is very small as non-overlap length is between 100 μm and 180 μm for 500 μm≤L≤1200 μm. The capacitance error caused by the fringe effect is the smallest for the slot distance 35 μm, slot depth 25 μm and slot width 20 μm. The error of sensing displacement caused by the fringe effect of the comb capacitor is 0.61% obtained by MATLAB Simulink. [ABSTRACT FROM PUBLISHER]

Abstract: The combs of the comb capacitive inertial sensors fabricated by a deep reactive ion etching are usually not parallel. This non-ideal feature is greater in high aspect ratio structure and significantly affects the capacitance and electrostatic force. In this paper, the effects of non-parallel combs on the reliable operation range for step and pulse signals in three capacitive configurations are investigated when alternative electronic testing signals are applied on the sensors for detecting the variation of capacitance. Analytical expressions of the critical step acceleration and the critical time duration of pulse acceleration of the capacitive sensor whose comb electrodes have little angle of the decline are obtained. Results show that for a step inertial signal, even the angle of the decline is 0.5°, the reliable operation ranges of the sensor with single-sided structure, double-sided structure and double-sided structure with feedback voltage are diminished to 0.34, 0.44 and 0.54 of the ones whose comb electrodes are parallel, respectively, for pulse inertial signal, the reliable operation ranges with single-sided structure and double-sided structure are diminished to 0.45 and 0.56, respectively, and the ones of double-sided capacitive sensor with feedback voltage are diminished to 0.95 as the angle is changed from 0.1° to 0.15°, which show that the effects of the non-parallel can not also been ignored. Results also show that the reliable dynamic operation ranges of the sensor with double-sided comb capacitive structure are least affected by the effects of non-parallel plates and its merit is more evident as the angle of the decline of the comb electrodes increases. Compared to the effects of non-parallel comb electrodes on the reliable operation range for step inertial signal, the effects for pulse inertial signal are smaller. [Copyright &y& Elsevier]

This paper discusses the vibration-induced error in non-ideal MEMS tuning fork gyroscopes (TFGs). Ideal TFGs which are thought to be immune to vibrations do not exist, and imbalance between two gyros of TFGs is an inevitable phenomenon. Three types of fabrication imperfections (i.e., stiffness imbalance, mass imbalance, and damping imbalance) are studied, considering different imbalance radios. We focus on the coupling types of two gyros of TFGs in both drive and sense directions, and the vibration sensitivities of four TFG designs with imbalance are simulated and compared. It is found that non-ideal TFGs with two gyros coupled both in drive and sense directions (type CC TFGs) are the most insensitive to vibrations with frequencies close to the TFG operating frequencies. However, sense-axis vibrations with in-phase resonant frequencies of a coupled gyros system result in severe error outputs to TFGs with two gyros coupled in the sense direction, which is mainly attributed to the sense capacitance nonlinearity. With increasing stiffness coupled ratio of the coupled gyros system, the sensitivity to vibrations with operating frequencies is cut down, yet sensitivity to vibrations with in-phase frequencies is amplified. [ABSTRACT FROM AUTHOR]

As a new type of one-dimensional semiconductor nanometer material, silicon nanowires (SiNWs) possess good application prospects in the field of biomedical sensing. SiNWs have excellent electronic properties for improving the detection sensitivity of biosensors. The combination of SiNWs and field effect transistors (FETs) formed one special biosensor with high sensitivity and target selectivity in real-time and label-free. Recently, SiNW-FETs have received more attention in fields of biomedical detection. Here, we give a critical review of the progress of SiNW-FETs, in particular, about the reversible surface modification methods. Moreover, we summarized the applications of SiNW-FETs in DNA, protein, and microbial detection. We also discuss the related working principle and technical approaches. Our review provides an extensive discussion for studying the challenges in the future development of SiNW-FETs. [ABSTRACT FROM AUTHOR]

We propose an approach to improve the performance of graphene-based gas sensors by the integration of defective graphene with pristine graphene. The defect density of defective graphene is controlled by the fluence of Si+ implantation, and an H2 etching process is utilized to tune defect size. As defects are able to adsorb target gas efficiently, the response of graphene-based sensors was improved remarkably with the controllable defect density. The response sensitivity of a defective-graphene-based sensor to concentrations of NO2 at 100 ppm can be as high as 248%, 13 times higher than that of a sensor built using pristine graphene. In addition, defective-graphene-based sensors exhibit high response and recovery rates at room temperature, which is comparable to those of pristine graphene-based sensors and faster than conventional defect-decorated graphene sensors. Most importantly, defective-graphene-based gas sensors exhibit excellent reproducibility, stability, and selectivity. Our study suggests a simple and effective strategy for the mass production of high-performance graphene-based gas sensors for NO2 gas detection. [ABSTRACT FROM AUTHOR]

ZnMn 2 O 4 is regarded as one of the potential anode materials for lithium-ion batteries (LIBs), due to its high theoretical specific capacity (784 mAh g −1 ). Unfortunately, the bulk ZnMn 2 O 4 presents an inferior electrochemical performance resulting from the large volume change during the charge-discharge process. In this paper, we report the synthesis and electrochemical properties of ZnMn 2 O 4 nanoparticles (NPs) that are homogeneously distributed in connective network porous carbon nanofibers wrapped by reduced graphene oxide sheets. The distinctive structure of this composite not only provides enough voids to storage Li-ions and buffer the volume expansion of the ZnMn 2 O 4 NPs, but also offers a continuous conducting network for Li-ion and electron transportation, resulting in significantly improved electrochemical performances. As binder-free electrodes for LIBs, an optimized ZnMn 2 O 4 @rGO-CNFs sample exhibits a reversible capacity of 1142 mAh g −1 at 100 mA g −1 over 100 cycles, and a stable capacity of 659 mAh g −1 after 1000 cycles at a large current density of 2000 mA g −1 , enabling ZnMn 2 O 4 a promising electrode candidate for LIBs. [ABSTRACT FROM AUTHOR]

Two dimensional electron systems (2DES) usually show the weak localization behavior in consequence of electron interaction in the limited dimension. Distinct from other 2DES, the monolayer graphene, due to the chirality, exhibits unique weak localization behavior sensitive to not only inelastic but also elastic carrier scattering. Grain boundaries, which usually exist in monolayer graphene, are apparently related to the elastic carrier scattering process, thus affecting the weak localization behavior. However, their effect is scarcely studied due to the lack of an ideal platform. Here, a complementary system consisting of both single-crystalline graphene grown on Ge (110) and poly-crystalline graphene grown on Ge (111) is constructed. From the comparison of magnetoresistivity measurements, the weak localization effect is found to be greatly enhanced for the poly-crystalline graphene on Ge(111) compared to the single-crystalline graphene on Ge(110). The degraded transport performance in graphene/Ge(111) is due to the presence of grain boundary in poly-crystalline graphene, which results in the enhanced elastic intervalley scattering. In addition, the inelastic scattering originating from the strong electron-electron interaction at low temperature also contributes to weak localization of poly-crystalline graphene/Ge(111). [ABSTRACT FROM AUTHOR]

This paper presents a high-frequency equivalent circuit model for on-chip coupled carbon nanotube (CNT) interconnects up to 100 GHz. By simplifying the circuit model, the S-parameters of on-chip coupled interconnects can be acquired and validated by comparing with the full-wave electromagnetic simulations. By virtue of effective complex conductivity, the high-frequency behaviors of coupled CNT interconnects are captured and studied, with the impacts of kinetic inductance treated appropriately. [ABSTRACT FROM PUBLISHER]

Table tennis competition is voted as one of the most popular competitive sports. The referee umpires the competition mainly based on visual observation and experience, which may make misjudgments on competition results due to the referee's subjective uncertainty or imprecision. In this work, a novel intelligent umpiring system based on arrayed self-powered acceleration sensor nodes was presented to enhance the competition accuracy. A sensor node array model was established to detect ball collision point on the table tennis table. This model clearly illuminated the working mechanism of the proposed umpiring system. And an improved particle swarm optimization (level-based competitive swarm optimization) was applied to optimize the arrayed sensor nodes distribution by redefining the representations and update rules of position and velocity. The optimized results showed that the number of sensors decreased from 58 to 51. Also, the reliability of the optimized nodes distribution of the table tennis umpiring system has been verified theoretically. The results revealed that our system achieved a precise detection of the ball collision point with uniform error distances below 3.5 mm. Besides, this research offered an in-depth study on intelligent umpiring system based on arrayed self-powered sensor nodes, which will improve the accuracy of the umpiring of table tennis competition. [ABSTRACT FROM AUTHOR]

Sound as a ubiquitous energy in our surroundings is clean and sustainable, and carries abundant information in a wide frequency bandwidth. However, effectively harvesting and utilizing acoustic energy is still hindered by the limitations such as low energy density of acoustic energy and lack of novel application. In this paper, we successfully present a self-powered acoustic sensor, which is composed of an adjustable spacing structure and sound-driven triboelectric nanogenerator (TENG). The acoustic sensor exhibits excellent electric output properties because of the poriferous electrode structure, ultrathin vibrating membrane as well as high-quality triboelectric materials. The sensor can deliver a maximal output voltage of 6.28 V with the sound frequency of 350 Hz and sound pressure of 110 dB. In addition, the electric output frequency is closely related to the applied acoustic wave and the corresponding directional dependence pattern as a butterfly is highly symmetrical. Our approach presents a cost-effective strategy to develop self-powered acoustic sensor and shows great potentials in home automation, self-powered microphone, sensor network and artificial intelligence. [ABSTRACT FROM AUTHOR]

In this paper, a few-layer WS 2 nanosheets-based electrochemical biosensor was fabricated for the highly sensitive detection of breast cancer tumor marker miRNA-4484. Firstly, few-layer WS 2 nanosheets were prepared by shear stripping and characterized by SEM, TEM, AFM and UV spectrophotometer. After modification of few-layer WS 2 nanosheets on the electrode surface, the miRNA probe was fixed on the few-layer WS 2 nanosheets by polycytosine (PolyC). Then short-chain miRNA containing PolyC was used as the blocking agent to close the excess active sites on the surface of WS 2 nanosheets to complete the fabrication of the sensor biosensing interface. Finally, the current changes caused by the specific binding of miRNA-4484 to the probe were analyzed by differential pulse voltammetry (DPV). The results showed that the sensor had a good linear relationship for the detection of miRNA-4484 in the concentration range of 1 aM–100 fM, and the detection limit was as low as 1.61 aM. In addition, the electrochemical sensor had excellent selectivity, stability and reproducibility. The artificial sample tests indicated that the developed biosensors have the potential for clinical application in the future. [Display omitted] • A few-layer WS 2 nanosheets-based electrochemical biosensor is developed for miRNA-4484. • The nanosheets (Thickness: ∼10 nm, Layers: ∼10 layers) are prepared by shear stripping. • Ultra-low detection limit (1.61 aM) with good linearity in the range of 1 aM–100 fM. • High specificity for miRNA-4484 and excellent stability, reproducibility. [ABSTRACT FROM AUTHOR]

Harvesting energy from natural water evaporation has been proposed as a promising alternative to supply power for self‐powered and low‐power devices and systems, owing to its spontaneous, ubiquitous, and sustainability. Herein, an approach is presented for harvesting water‐evaporation‐induced electricity based on liquid–solid triboelectric nanogenerators (LS‐TENGs), which has various advantages of easy preparation, substrate needless, and robustness. This developed harvester with porous Al2O3 ceramic sheet can generate a continuous and stable direct current of ≈0.3 µA and voltage of ≈0.7 V by optimizing the sheet physical dimensions and ambient parameters such as relative humidity, temperature, wind velocity, and ion concentration. The output power also can be improved significantly by series or parallel connection the harvesters, which has superior electrical compatibility and environmental suitability. The development of the water‐evaporation‐induced electricity harvesting shows many application prospects including power supply for digital calculator and charging capacitor. This research provides an in‐depth experimental study on water‐evaporation‐induced electricity harvesting based on LS‐TENGs and an efficient approach to supply electricity for low‐power devices. [ABSTRACT FROM AUTHOR]

Breast cancer has the highest cancer incidence rate in women. Early screening of breast cancer can effectively improve the treatment effect of patients. However, the main diagnostic techniques available for the detection of breast cancer require the corresponding equipment, professional practitioners, and expert analysis, and the detection cost is high. Tumor markers are a kind of active substance that can indicate the existence and growth of the tumor. The detection of tumor markers can effectively assist the diagnosis and treatment of breast cancer. The conventional detection methods of tumor markers have some shortcomings, such as insufficient sensitivity, expensive equipment, and complicated operations. Compared with these methods, biosensors have the advantages of high sensitivity, simple operation, low equipment cost, and can quantitatively detect all kinds of tumor markers. This review summarizes the biosensors (2013–2021) for the detection of breast cancer biomarkers. Firstly, the various reported tumor markers of breast cancer are introduced. Then, the development of biosensors designed for the sensitive, stable, and selective recognition of breast cancer biomarkers was systematically discussed, with special attention to the main clinical biomarkers, such as human epidermal growth factor receptor-2 (HER2) and estrogen receptor (ER). Finally, the opportunities and challenges of developing efficient biosensors in breast cancer diagnosis and treatment are discussed. [ABSTRACT FROM AUTHOR]

For capacitive sensing, a driving signal with a dc bias voltage and an ac voltage is usually necessary for the measurement of capacitance. The electrostatic forces caused by the driving signal on the mechanical capacitor may interfere significantly with the measurement and the normal operation of the devices. In this paper, quantitative analyses on the effects of driving signal with different bias voltage polarities are made for double-sided driving and double-sided driving with voltage feedback. For double-sided driving, the effects of the dc bias voltage with different polarities on devices are the same. For double-sided driving with voltage feedback, positive–positive and positive–negative bias voltage configurations may improve the measurement linearity of the device and mostly eliminate the pull-in effect caused by the driving signal, while negative–negative and negative–positive bias voltage configurations maximize the side effects of the driving signal and reduce largely the safe operation range of the device. [Copyright &y& Elsevier]

A high‐precision differential microwave dielectric sensor system based on a pair of CSRR‐SIW resonators is introduced. The proposed method consists of four parts: the frequency‐sweeping signal source, the balanced sensor based on CSRR‐SIW, the RMS power detector, and the data acquisition system. Without a vector network analyzer (VNA) and other instruments, the electromagnetic properties of materials can be measured conveniently with the proposed method. In this work, two CSRR resonators inside SIW cavities are used as the balanced RF sensing components, one for measurement and the other for reference. In virtue of the electric field concentration effect of the CSRR and the high Q factor of SIW cavity, the proposed sensor achieves high sensitivity to material under test (MUT), with high isolation between the balanced resonators and strong capability of suppressing the electromagnetic interferences from the external environment. The resonating frequency of the balanced microwave resonator under no‐load condition is 1.587 GHz. With balanced sensor configuration, interferences from the external environment and fabrication errors for the single‐resonator‐based system can be filtered out and compensated automatically, and thus high precision of the dielectric constant measurement can be achieved. The experiment results of proposed differential dielectric sensor system validate that the measurement accuracy of the dielectric constant can reach an excellent level with a relative measurement error below 0.1%. [ABSTRACT FROM AUTHOR]

Allatostatin (AS) or Allatotropin (AT) is a class of insect short neuropeptide F (sNPF) that affects insect growth and development by inhibiting or promote the synthesis of juvenile hormone (JH) in different insects. III-2 is a novel sNPF analog derived from a group of nitroaromatic groups connected by different amino acids. In this study, we found that III-2 showed high insecticidal activity against S. frugiperda larvae with a LC 50 of 18.7 mg L−1. As demonstrated by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), III-2 particularly facilitated JH III and hindered 20E synthesis in S. frugiperda. The results of RNA-Seq and quantitative real-time polymerase chain reaction (qPCR) showed that III-2 treatment promoted the expression of key genes such as SfCYP15C1 in JH synthesis pathway and inhibited the expression of SfCYP314A1 and other genes in the 20E synthetic pathway. Significant differences were also observed in the expression of the genes related to cuticle formation. We report for the first time that sNPF compounds specifically interfere with the synthesis and secretion of a certain JH in insects, thus affecting the ecdysis and growth of insects, and leading to death. This study may provide a new plant conservation concept for us to seek the targeted control of certain insects based on specific interference with different JH. [Display omitted] • A short neuropeptide F (sNPF) analog III-2 has good insecticidal activity against S. frugiperda. • III-2 specifically promote the synthesis of JH III, but has no effect on the titers of JH I and JH II. • III-2 inhibited the synthesis of 20E in S. frugiperda. • It lays a theoretical foundation for the development of sNPF related JH targeted insecticides. [ABSTRACT FROM AUTHOR]

The toxic effects of neonicotinoid pesticides on honeybees is a global concern, whereas little is known about the effect of stereoisomeric pesticides among honeybee social behavior. In this study, we investigated the effects of stereoisomeric dinotefuran on honeybee social behavior. We found that honeybees exhibit a preference for consuming food containing S-dinotefuran, actively engage in trophallaxis with S-dinotefuran–consuming peers, and consequently acquire higher levels of S-dinotefuran compared with R-dinotefuran. In comparison to R-dinotefuran, S-dinotefuran stimulates honeybees to elevate their body temperature, thereby attracting more peers for trophallaxis. Transcriptome analysis revealed a significant enrichment of thermogenesis pathways due to S-dinotefuran exposure. Additionally, metabolome data indicated that S-dinotefuran may enhance body temperature by promoting lipid synthesis in the lysine degradation pathway. Consequently, body temperature emerges as a key factor influencing honeybee social behavior. Our study is the first to highlight the propensity of S-dinotefuran to raise honeybee body temperature, which prompts honeybee to preferentially engage in trophallaxis with peers exhibiting higher body temperatures. This preference may lead honeybees to collect more dinotefuran-contaminated food in the wild, significantly accelerating dinotefuran transmission within a population. Proactive trophallaxis further amplifies the risk of neonicotinoid pesticide transmission within a population, making honeybees that have consumed S-dinotefuran particularly favored within their colonies. These findings may contribute to our understanding of the higher risk associated with neonicotinoid use compared with other pesticides. [Display omitted] • Honeybees favor S-dinotefuran–infused food. • Honeybees prefer trophallaxis with peers that have fed on S-dinotefuran. • Proactive trophallaxis speeds dinotefuran diffusion. • S-dinotefuran stimulates higher honeybee body temperature compared with R-dinotefuran. [ABSTRACT FROM AUTHOR]

Passive micro direct methanol fuel cell (μDMFC) which operates based on fuel diffusion is preferred for portable applications for its structural simplicity. In this work, we have systematically investigated multiple variables including the hot-press conditions, current collector channel patterns, current collector open ratios, and their effects on the performance for passive μDMFC by experiments and simulations. Results indicate that vertical stripe pattern (VSP) is preferred for both anodes and cathodes due to the upward reaction products drift by natural convection. Open ratio of 45.6% and 35.8% are found to yield the best performance for anode and cathode, respectively. In addition, the external environmental conditions of vibration frequency, cell orientation, environmental temperature and atmospheric pressure are all discussed in detail in this work. The optimized fabrication, assembly and operation parameters shed light on the design considerations necessary for the wide adaptation of high-performance and durable passive μDMFC for portable applications. • Hot-pressing parameters of pressure, time and temperature are optimized. • A 3D model considering contact resistance is established. • The current collectors with different channel patterns are evaluated. • The current collectors with different open ratios are optimized. • The effects of external environmental parameters are evaluated. [ABSTRACT FROM AUTHOR]

Nozzleless jetting of droplets with different jetting angles is a crucial requirement for 2D and 3D printing/bioprinting applications, and Rayleigh mode surface acoustic waves (SAWs) could be a potential technique for achieving this purpose. Currently, it is critical to vary the jetting angles of liquid droplets induced by SAWs and control the liquid jet directions. Generally, the direction of the liquid jet induced by SAWs generated from a bulk piezoelectric substrate such as LiNbO3 is along the theoretical Rayleigh angle of ∼22°. In this study, we designed and manufactured thin-film SAW devices by depositing ZnO films on different substrates (including silicon and aluminium) to realize a wide range of jetting angles from ∼16° to 55° using propagating waves generated from one interdigital transducer. We then systematically investigated different factors affecting the jetting angles, including liquid properties, applied SAW power and SAW device resonant frequency. Finally, we proposed various methods using thin-film SAW devices together with different transducer designs for realizing a wide range of jetting angles within the 3D domain. A nozzleless jetting method is proposed using thin-film based surface acoustic wave devices to achieve a wide range of jetting angles for droplets. [ABSTRACT FROM AUTHOR]

Synthesis of graphene on Ni/Cu bilayer substrate by ion implantation is sensitive to the quality of the Ni/Cu substrate. In this work, different pretreatments of Cu foils were implemented to elucidate the role of Cu pretreatment on graphene synthesis. Four types of pretreatments including polishing, annealing at 950 °C, annealing at 1000 °C, and annealing at 1050 °C were conducted prior to the growth of the Ni coating layer. Four different Ni/Cu substrates were implanted by carbon ions and annealed to obtain monolayer graphene. It shows that the impurity particles emerging on the Cu foils annealed at 1000 °C and 1050 °C affect the crystalline quality of the synthesized graphene. In addition, the increase in roughness due to the polishing process induces non-uniformity of the obtained graphene. Overall, annealing at 950 °C is proven to be the proper pretreatment for Cu foil, and the corresponding graphene film has excellent crystalline quality and uniformity compared to those obtained on the substrates with other pretreatments. [ABSTRACT FROM AUTHOR]

Water droplets are ubiquitous in nature and harvesting droplet kinetic energy has attracted a great deal of attention to meet the increasing worldwide energy demands. In this work, we report a water droplet motion energy harvester with the wafer-level fabrication method, which is based on the water–solid surface contact electrical double layer effect. A theoretical model is established to illuminate the water droplet motion energy harvesting mechanism. Guided by the model, an energy harvester is developed based on Micro Electro-Mechanical Systems compatible process technology, which achieve a wafer-level fabrication. The output performance of the energy harvester has been optimized by decreasing the electrode width and its interval. Experimental results also show that the output voltage can be improved by increasing the droplet volume and decreasing the ionic concentration. The optimized energy harvester exhibits an open circuit output peak voltage of 57.5 mV. This research provides an in-depth theoretical study and a practical guidance on water droplet kinetic energy harvesting. [ABSTRACT FROM AUTHOR]

The adsorption of various gas molecules (H2, H2O, CO, NH3, NO and NO 2) on monolayer GeSe were investigated by first-principles calculations. The most stable configurations, the adsorption energies, and the amounts of charge transfer were determined. Owing to the appropriate adsorption energies and the non-negligible charge transfers, monolayer GeSe could be a promising candidate as a sensor for NH3, CO, NO and NO2. According to the band structures of the H2O, CO, NH3, NO and NO2 adsorbed systems, the reductions of the bandgaps are caused by the orbital hybridizations between the gas molecules and the underlying GeSe. The partial densities of states reveal the degrees of these orbital hybridizations. The mechanisms of charge transfer are discussed in the light of both traditional and orbital mixing charge transfer theories. The charge transfer of the paramagnetic molecules NO and NO2 could be governed by both charge transfer mechanisms, while for the other gas molecules H2, H2O, CO and NH3, it was most likely determined by the mixing of the HOMO or LUMO with the GeSe orbitals. Monolayer GeSe can be a promising candidate for sensing NH3, CO, NO, and NO2 on the base of the appropriate adsorption energies and the non-negligible charge transfers. The charge transfers of the paramagnetic molecules (NO and NO2) are governed by both the traditional and the orbital mixing charge transfer theories, while for NH3 and CO, it is most likely determined by the mixing of the molecular HOMO or LUMO with the orbitals of GeSe. [ABSTRACT FROM AUTHOR]

Abstract Although strain engineering is an effective method to modify the bandgap of germanium for germanium-based microelectronic, the introduction of biaxial tensile strain with a particular pattern to germanium is challenging. Herein, a facile approach to produce biaxially strained germanium micro-dot arrays by hydrogen ion implantation is described. By changing the ion implantation and annealing conditions, the morphology of the micro-dots can be optimized and the biaxially tensile strain can be tuned to a maximum value of 0.6%. This method which is compatible with mainstream complementary metal-oxide-semiconductor processing can be extended to strain engineering in wafer scale. Highlights • An approach to fabricate the array of biaxially strained micro-dots by hydrogen implantation. • The magnitude of strain in the micro-dot can be effectively adjusted by the annealing temperature. • The strain in the micro-dots originates from the formation of internal crack induced by the aggregation of hydrogen. [ABSTRACT FROM AUTHOR]

Tactile force sensor has attracted considerable interests owing to its great application prospects in human-computer interaction systems, intelligent robots, wearable medical devices and other fields. The key to achieve this sensor is (1) high sensitivity and low crosstalk, (2) fast response time and (3) the economy of fabricating macroscopic sensors on flexible substrates. However, low-cost tactile sensors reported hitherto cannot simultaneously achieve high sensitivity, low crosstalk and fast response time. In this study, we report an all-printed 4 × 4 capacitive array tactile sensors using PDMS with innovative island-structure and printable nanocomposite inks as dielectric layer and electrodes, respectively. By changing the geometry parameters of the island-structure of the dielectric layer, the sensors can achieve adjustable sensitivity while effectively reducing crosstalk between sensing elements, leading to accurate position perception of the applied pressure. The sensitivity of the sensor can reach 0.76 kPa−1 in the range of 0–1 kPa, and 0.2 kPa−1 in the range of 1–15 kPa. Moreover, the sensor exhibits a fast response time (∼50 ms) and low detection limit (∼2 Pa). These achievements have rarely been reported in a fully printed tactile force sensor. As a proof of concept for fully printed high sensitivity and low crosstalk sensor, human motion and sound signal detection were finally demonstrated. The advantages of the array sensors afford several applications, including low-cost, wide-range flexible wearable devices for measuring signals from a user, rehabilitation training and human-computer interaction, etc. [Display omitted] • Circular radiation-shaped microstructures dielectric layer that prevents crosstalk between sensing elements is proposed. • Capacitive array tactile force sensors with tunable sensitivity are fabricated by full printing technology. • A low-cost manufacturing progress and procedure to fabricate the array tactile force sensors is proposed. [ABSTRACT FROM AUTHOR]

To solve electrical contact problem of horizontal multilayer graphene nanoribbon (GNR), a vertical GNR (VGNR) interconnect scheme is proposed. Performance of the VGNR interconnect is theoretically evaluated and compared with those of conventional interconnect technologies. It is shown that the performance of VGNR is comparable (and even superior) to that of the horizontal GNR (HGNR). Moreover, VGNRs may provide a promising solution to the thermal challenges faced by HGNRs in nanoscale ICs. [ABSTRACT FROM AUTHOR]

First-principles calculations were performed to investigate the interaction of small gas molecules, including H 2 , O 2 , H 2 O, NH 3 , NO, NO 2 , and CO, with monolayer GaSe. The energetics, charge transfer and band structures were evaluated by considering the Grimme-D2 correction. Due to the low adsorption energies and the moderate charge transfer, monolayer GaSe could be a promising candidate as a sensor for O 2 and NO 2 . The theoretical results for adsorption of O 2 on monolayer GaSe are consistent well with the most recent experimental observation. Diverse projected band structures of these gas molecule-adsorbed systems demonstrate that there exist two kinds of charge transfer mechanisms: traditional and orbital mixing theories. Based on the proposed charge transfer mechanisms, external strain exerted different influences on the charge transfer for gas molecules adsorbed on the GaSe monolayer. The present study provides theoretical insight leading to a better understanding of the novel two-dimensional materials, such as graphene, phosphorene, and transition metal dichalcogenides. [ABSTRACT FROM AUTHOR]

Impact-based vibration energy harvesters (VEHs) with a rolling proof mass are promising candidates for scavenging ambient low-level, broadband, and low-frequency vibration energy. This paper derives the mathematical model of a VEH with two piezoelectric cantilevers symmetrically located at two open ends of a guiding channel with a rolling steel ball inside as the proof mass. The model includes the equation of motion and coupled electrical circuit equation of the bimorphs under base excitation, the equations of motion of the rolling proof mass under base excitation, and the collision equations between the bimorphs and the proof mass. Simulation results show that the scavenging efficiency of low-level vibration can be improved by introducing the rolling proof mass. The numerical results agree well with the experiments when the harvester prototype is horizontally fixed on the base. Under the base excitation of 1 g(=9.8 m/s 2 ), the maximum output power of one bimorph is about 511 μW at 18.4 Hz. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel stretchable electrode was made by electrospinning and ultrasonic treatment. • The superior merits included high stretchability, conductivity and air permeability. • The wearable heaters, strain sensors and supercapacitor electrodes were demonstrated. As smart wearable electronics become commonplace, there exists an unmet need for stretchable, durable and breathable electrodes that can be easily integrated with the electronics and comfortable for the users when used for extended periods. Despite the enormous effort in the development of stretchable electronic materials and structures, limited progress has been made in terms of developing a facile, scalable fabrication process to produce mechanically and electrically robust, breathable conductive electrodes for wearable electronics. Herein, we develop a novel stretchable polymer-carbon nanotube composite electrode based on a fibrous polyurethane mat decorated with conductive carbon nanotubes superficially embedded into individual polyurethane fibers. The fibrous polyurethane mat is fabricated through a facile technique of electrospinning, followed by a scalable ultrasonic cavitation treatment in a carbon nanotubes suspension solution. During ultrasonic cavitation treatment, long carbon nanotubes are embedded into electrospun polyurethane fibers and mechanically interlocked with one other, forming a dense, structurally robust, and electrically stable conductive network surrounding each fiber. The as-fabricated electrodes exhibit several superior properties that are characterized by good stretchability (recoverable stretching rate up to 200 %), high conductivity (low sheet resistance of 30 ∼ 50 Ω/sq), excellent stability (over 20,000 bending and stretching cycles), remarkable durability (capable of ultrasonic washing for over 30 min), and efficient air permeability (22.83 mm s−1 at a pressure difference of 100 Pa). Based on the integrated superior performances, the multifunctional capability of this novel electrode for wearable electronics is demonstrated in applications including thin-film heaters, strain sensors, and wearable energy supply of stretchable supercapacitor electrodes. It is supposed that the developed fabrication process and stretchable electrodes could be a versatile platform for development of flexible and wearable electronics. [ABSTRACT FROM AUTHOR]

Cancer has become one of the major diseases threatening human health and life. Circulating tumor DNA (ctDNA) testing, as a practical liquid biopsy technique, is a promising method for cancer diagnosis, targeted therapy and prognosis. Here, for the first time, a field effect transistor (FET) biosensor based on uniformly sized high-response silicon nanowire (SiNW) array was studied for real-time, label-free, super-sensitive detection of PIK3CA E542K ctDNA. High-response 120-SiNWs array was fabricated on a (111) silicon-on-insulator (SOI) by the complementary metal oxide semiconductor (CMOS)-compatible microfabrication technology. To detecting ctDNA, we modified the DNA probe on the SiNWs array through silanization. The experimental results demonstrated that the as-fabricated biosensor had significant superiority in ctDNA detection, which achieved ultralow detection limit of 10 aM and had a good linearity under the ctDNA concentration range from 0.1 fM to 100 pM. This biosensor can recognize complementary target ctDNA from one/two/full-base mismatched DNA with high selectivity. Furthermore, the fabricated SiNW-array FET biosensor successfully detected target ctDNA in human serum samples, indicating a good potential in clinical applications in the future. • A biosensor based on uniform dimensions high-response SiNW array was studied for PIK3CA E542K ctDNA detection. • 120 SiNWs with high consistency of dimensions make the signal superimpose, resulting in a higher signal-to-noise ratio. • Ultra-low detection limit (10 aM ctDNA) and a good linear relationship between 0.1 fM to 100 pM. • High specificity for the recognition of PIK3CA E542K ctDNA and excellent repeatability, reproducibility. [ABSTRACT FROM AUTHOR]

• Synthesis of porous PAN/S nanofibers by using electrospinning method. • Porous nanofibrous morphology enhances the ions and electrons conductivity. • The porous PAN/S shows a high reversible capacity of 1144 mA h g−1 after 100 cycles at 0.2 C. • The porous PAN/S delivers a high rate performance with capacity of 794 mAh g−1 at 2 C after 500 cycles. ga1 Lithium–sulfur (Li–S) batteries have attracted great interest for next-generation batteries owing to their high capacity density and low cost. However, the drawbacks of the low conductivity of sulfur, serious "shuttle effect" and huge volume expansion during the charging/discharging cycles greatly limit their practical applications. In this work, we report the synthesis of porous sulfurized poly(acrylonitrile) (PAN/S) nanofibers via thermal treatment of PAN/poly(methyl methacrylate) (PMMA) nanofibers with elemental sulfur, resulting in 48 wt% of covalently bound sulfur formed in the composite. The unique porous structure of nanofibers enables enhanced diffusion dynamics of ions and electrons, thus improving the reactivity and conductivity of sulfur. As a consequence, the porous PAN/S cathode delivers a high reversible capacity of 1144 mA h g−1 after 100 cycles at a current rate of 0.2 C and a high rate performance with a reversible discharge capacity of 794 mA h g−1 at 2 C after 500 cycles. [ABSTRACT FROM AUTHOR]

Transition-metals have emerged as promising catalyst candidates for improving the hydrogen storage properties of MgH2. However, the preparation of uniformly dispersed and extra-fine transition-metals catalysts with high catalytic activity still remains a challenge. In this paper, an electrospinning-based reduction approach is presented to generate nanostructured nickel catalyst, which is protected from irreversible fusion and aggregation in subsequent high-temperature pyrolysis, in carbon nanofibers (Ni@C) in situ. The obtained Ni@C reveals remarkable catalytic effect on improving the hydrogen storage properties of MgH2. For example, the MgH2-10 wt%Ni@C composite delivers dehydrogenation capacities of 5.79 wt% and 6.12 wt% at 280 °C and 300 °C, respectively, whereas the as-milled MgH2 hardly decomposes at the same temperature. By Arrhenius plots, the calculated Ea of the dehydrogenation of MgH2-10 wt%Ni@C is 93.08 kJ mol−1, which is 94.33 kJ mol−1 lower than that of the as-milled MgH2. Furthermore, the microstructure of Ni@C is remained during the re/dehydrogenation process and the Ni nanoparticles are still distributed homogeneously in the composite, accounting for the excellent cycling performance. This study could render combinations of ultrafine metal nanoparticles with carbon accessible, thereby, extending opportunities in catalytic applications for hydrogen storage. The homogeneously distributed Ni with refined particle size in carbon nanofibers has been synthesized successfully. A certain proportion of Ni@C and commercial MgH 2 were mechanically mixed by high-energy ball milling and the Ni@C were uniformly dispersed on the surface of MgH 2 , which enhanced the interface interaction and reduced the apparent activation energy of the dehydrogenation of MgH 2 -10 wt % Ni@C. Image 1 • Ni nanoparticles in-situ encapsulated in carbon nanofibers has been synthesized successfully by electrospinning technique. • The Ni@C catalyst was uniformly dispersed on the surface of MgH 2 by high-energy ball milling. • The MgH 2 -10 wt %Ni@C delivers a hydrogen release of 5.91 wt% in 500 s at 325 °C. • The hydrogen storage capacity of the MgH 2 -10 wt %Ni@C composite can be maintained without degradation after 20 cycles. [ABSTRACT FROM AUTHOR]

• The large-area Ag nanoprism array with well-matched resonance was prepared. • Ag/WS 2 plasmonic hybrid structure with compact contact was fabricated. • The Ag nanoprism array has a better enhancement effect on the neutral exciton of monolayer WS 2. • The intensity of feature modes and A 1g of WS 2 is greatly enhanced by a factor of 3 and 4, respectively. Monolayer transition metal dichalcogenides (TMDs) usually have weak optical emission due to the poor light absorption as being atomically thin. Enhancing their optical properties by surface plasmon resonance is attractive for applying atomically thin TMDs in optoelectronic and photonic devices. Here, Ag/WS 2 hybrid structure was fabricated by transferring monolayer WS 2 grown via chemical vapor deposition (CVD) onto optimized periodic Ag nanoprism array with well-matched resonance by controlling the mask geometry and etching time of polystyrene (PS) nanospheres. Significant enhanced photoluminescence (PL) emission and Raman scattering were successfully achieved. Especially, the higher enhancement is realized for neutral excitons of monolayer WS 2. Theoretical calculations reveal that the plasmonic enhancement mainly results from the highly enhanced local electric field and the charge transfer. This work explores the feasibility of exciton emission and Raman scattering enhancement for TMDs with plasmonic nanostructures fabricated by low-cost and easily-manipulated nanosphere lithography (NSL), which paves a way towards the applications of plasmon-enhanced TMD sensors, emitters, and photodetectors. [ABSTRACT FROM AUTHOR]

Active SIW-based sensor terminated with negative resistance circuit. • A microwave sensor based on SIW technology for characterization of MD materials is for the first time reported. • The proposed sensor has the ability for measuring both complex permittivity and complex permeability. • By virtue of negative resistance circuit, the sensor exhibits higher quality factor than previous reported sensors. A high-Q sensor based on substrate integrated waveguide (SIW) technology is designed to fully characterize magneto-dielectric materials. By utilizing the negative resistance circuit, the quality factor is further increased to an ultrahigh value of 13,399. By virtue of the improved complementary split ring resonator (CSRR), the complex permittivity, as well as the complex permeability, can be extracted from variations of the resonant frequency and magnitude. A prototype of the designed active SIW-based sensor is fabricated and validated experimentally. A good agreement can be achieved between the measured values and the reference data. [ABSTRACT FROM AUTHOR]

A novel uniplanar dual‐band printed compound loop antenna for WLAN/WiMAX applications is proposed. The proposed antenna consists of a small inner rectangular ring, an outer rectangular loop with three slits and a parasitic strip on one side of the substrate. Fed by the inner ring and collaborated with double rings and the parasitic strip, three resonant frequencies can be achieved, where the parasitic metallic strip between the rings can not only induce a new middle resonant frequency but also improve the impedance matching at the low‐frequency band greatly. By magnetic‐electrical coupling, dual‐band performance with the lower‐wide band covering 2.37–3.78 GHz and the upper‐frequency band covering 5.15–5.85 GHz can be obtained. It is experimentally demonstrated that the proposed antenna with the performance of broadband (covering 2.4/5 GHz WLAN including 2.4–2.484 GHz, 5.15–5.825 GHz and 3.5/5 GHz WiMAX including 3.4–3.69 GHz, 5.25–5.85 GHz, respectively), good dipole‐like radiation characteristics, stable gain and high‐radiation efficiency, is an excellent candidate for WLAN/WiMAX applications. [ABSTRACT FROM AUTHOR]

Ammonia gas sensors are very essential in many industries and everyday life. However, their complicated fabrication process, severe environmental fabrication requirements and desorption of residual ammonia molecules result in high cost and hinder their market acceptance. Here, laser direct writing is used to fabricate three parallel porous 3D graphene lines on a polyimide (PI) tape to simply construct an ammonia gas sensor. The middle one works as an ammonia sensing element and the other two on both sides work as heaters to improve the desorption performance of the sensing element to ammonia gas molecules. The graphene lines were characterized by scanning electron microscopy and Raman spectroscopy. The response and recovery time of the sensor without heating are 214 s and 222 s with a sensitivity of 0.087% ppm−1 for sensing 75 ppm ammonia gas, respectively. The experimental results prove that under the optimized heating temperature of about 70 °C the heaters successfully help implement complete desorption of residual NH3 showing a good sensitivity and cyclic stability. [ABSTRACT FROM AUTHOR]