A Layered Energy-Efficient Multi-Node Scheduling Mechanism for Large-Scale WSN

In recent years, target tracking has been considered one of the most important applications of wireless sensornetwork (WSN). Optimizing target tracking performance and prolonging network lifetime are two equally criticalobjectives in this scenario. The existing mechanisms still have weaknesses in balancing the two demands. Theproposed heuristic multi-node collaborative scheduling mechanism (HMNCS) comprises cluster head (CH)election, pre-selection, and task set selectionmechanisms, where the latter two kinds of selections forma two-layerselection mechanism. The CH election innovatively introduces the movement trend of the target and establishesa scoring mechanism to determine the optimal CH, which can delay the CH rotation and thus reduce energyconsumption. The pre-selection mechanism adaptively filters out suitable nodes as the candidate task set to applyfor tracking tasks, which can reduce the application consumption and the overhead of the following task setselection. Finally, the task node selection is mathematically transformed into an optimization problem and thegenetic algorithm is adopted to form a final task set in the task set selection mechanism. Simulation results showthat HMNCS outperforms other compared mechanisms in the tracking accuracy and the network lifetime.

Use of a Digital Image Correlation Technique for Measuring the Material Properties of Beetle Wing

Beetle wings are very specialized flight organs consisting of the veins and membranes.Therefore it is necessary from a bionic view to investigate the material properties of a beetle wing experimentally.In the present study,we have used a Digital Image Correlation (DIC) technique to measure the elastic modulus of a beetle wing membrane.Specimens were prepared by carefully cutting a beetle hind wing into 3.0 mm by 7.0 mm segments (the gage length was 5 mm).We used a scanning electron microscope for a precise measurement of the thickness of the beetle wing membrane.The specimen was attached to a designed fixture to induce a uniform displacement by means of a micromanipulator.We used an ARAMISTM system based on the digital image correlation technique to measure the corresponding displacement of a specimen.The thickness of the beetle wing varied at different points of the membrane.The elastic modulus differed in relation to the membrane arrangement showing a structural anisotropy;the elastic modulus in the chordwise direction is approximately 2.65 GPa,which is three times larger than the elastic modulus in the spanwise direction of 0.84 GPa.As a result,the digital image correlation-based ARAMIS system was suc- cessfully used to measure the elastic modulus of a beetle wing.In addition to membrane's elastic modulus,we considered the Poisson's ratio of the membrane and measured the elastic modulus of a vein using an Instron universal tensile machine.The result reveals the Poisson's ratio is nearly zero and the elastic modulus of a vein is about 11 GPa.

Thrust Analysis of a Fish Robot Actuated by Piezoceramic Composite Actuators

In this work, a three-dimensional （3D） Computational Fluid Dynamics （CFD） model was built to simulate the tail fin motion of a fish robot actuated by a piezoceramic composite actuator, and to determine the maximum thrust tail-beat frequency. A simulation of the tail fin at a tail-beat frequency was performed to confirm measured thrust data from a previous study. The computed and measured thrusts were in good agreement. A series of thrust simulations were conducted for various tail-beat frequencies to confirm the maximum thrust frequency that was obtained from thrust measurements in the previous study. The largest thrust was calculated at a tail-beat frequency of 3.7 Hz and vortices around the tail were fully separated. The calculated maximum thrust tail-beat frequency was in good agreement with the measured frequency. Flow characteristics during tail fin motion were examined to explain why the largest thrust occurred at this particular tail-beat frequency.

Combination therapy using evening primrose oil and electrical stimulation to improve nerve function following a crush injury of sciatic nerve in male rats

Peripheral nerve injuries with a poor prognosis are common.Evening primrose oil（EPO） has beneficial biological effects and immunomodulatory properties.Since electrical activity plays a major role in neural regeneration,the present study investigated the effects of electrical stimulation（ES）,combined with evening primrose oil（EPO）,on sciatic nerve function after a crush injury in rats.In anesthetized rats,the sciatic nerve was crushed using small haemostatic forceps followed by ES and/or EPO treatment for 4 weeks.Functional recovery of the sciatic nerve was assessed using the sciatic functional index.Histopathological changes of gastrocnemius muscle atrophy were investigated by light microscopy.Electrophysiological changes were assessed by the nerve conduction velocity of sciatic nerves.Immunohistochemistry was used to determine the remyelination of the sciatic nerve following the interventions.EPO ＋ ES,EPO,and ES obviously improved sciatic nerve function assessed by the sciatic functional index and nerve conduction velocity of the sciatic nerve at 28 days after operation.Expression of the peripheral nerve remyelination marker,protein zero（P0）,was increased in the treatment groups at 28 days after operation.Muscle atrophy severity was decreased significantly while the nerve conduction velocity was increased significantly in rats with sciatic nerve injury in the injury ＋ EPO ＋ ES group than in the EPO or ES group.Totally speaking,the combined use of EPO and ES may produce an improving effect on the function of sciatic nerves injured by a crush.The increased expression of P0 may have contributed to improving the functional effects of combination therapy with EPO and ES as well as the electrophysiological and histopathological features of the injured peripheral nerve.

Effects of the Discharge Parameters on the Efficiency and Stability of Ambient Metastable-Induced Desorption Ionization

Ionization efficiency is an important factor for ion sources in mass spectrometry and ion mobility spectrometry.Using helium as the discharge gas,acetone as the sample,and high-field asymmetric ion mobility spectrometry（FAIMS） as the ion detection method,this work investigates in detail the effects of discharge parameters on the efficiency of ambient metastableinduced desorption ionization（AMDI） at atmospheric pressure.The results indicate that the discharge power and gas flow rate are both significantly correlated with the ionization efficiency.Specifically,an increase in the applied discharge power leads to a rapid increase in the ionization efficiency,which gradually reaches equilibrium due to ion saturation.Moreover,when the discharge voltage is fixed at 2.1 kV,a maximum efficiency can be achieved at the flow rate of 9.0 m/s.This study provides a foundation for the design and application of AMDI for on-line detection with mass spectrometry and ion mobility spectrometry.

Graphene Domains Synthesized on Electroplated Copper by Chemical Vapor Deposition

Electroplated Cu,which can be compatible with integrated circuit technology and large-scale silicon wafers,is explored as a substrate to synthesize graphene domains by ambient-pressure chemical vapor deposition.Hexagonal single crystal domains of graphene are synthesized on electroplated Cu under dilute methane gas flow.Scanning electron microscopy images of graphene domains grown on electroplated Cu indicate that the domain size is time-dependent,and the domains can cross Cu grain boundaries and are distributed more uniformly on electroplated Cu surface than those grown on Cu foil.

Open Journal of Applied Biosensor: Point-of-Care Biosensing and Environment Monitoring

Open Journal of Applied Biosensor: Point-of-Care Biosensing and Environment

Combining thermal scanning probe lithography and dry etching for grayscale nanopattern amplification

Grayscale structured surfaces with nanometer-scale features are used in a growing number of applications in optics and fluidics.Thermal scanning probe lithography achieves a lateral resolution below 10 nm and a vertical resolution below 1 nm,but its maximum depth in polymers is limited.Here,we present an innovative combination of nanowriting in thermal resist and plasma dry etching with substrate cooling,which achieves up to 10-fold amplification of polymer nanopatterns into SiO_(2) without proportionally increasing surface roughness.Sinusoidal nanopatterns in SiO_(2) with 400 nm pitch and 150 nm depth are fabricated free of shape distortion after dry etching.To exemplify the possible applications of the proposed method,grayscale dielectric nanostructures are used for scalable manufacturing through nanoimprint lithography and for strain nanoengineering of 2D materials.Such a method for aspect ratio amplification and smooth grayscale nanopatterning has the potential to find application in the fabrication of photonic and nanoelectronic devices.

Impedance spectroscopy of the cell/nanovolcano interface enables optimization for electrophysiology

Volcano-shaped microelectrodes have demonstrated superior performance in measuring attenuated intracellular action potentials from cardiomyocyte cultures. However, their application to neuronal cultures has not yet yielded reliable intracellular access. This common pitfall supports a growing consensus in the field that nanostructures need to be pitched to the cell of interest to enable intracellular access. Accordingly, we present a new methodology that enables us to resolve the cell/probe interface noninvasively through impedance spectroscopy. This method measures changes in the seal resistance of single cells in a scalable manner to predict the quality of electrophysiological recordings. In particular, the impact of chemical functionalization and variation of the probe’s geometry can be quantitatively measured. We demonstrate this approach on human embryonic kidney cells and primary rodent neurons. Through systematic optimization, the seal resistance can be increased by as much as 20-fold with chemical functionalization, while different probe geometries demonstrated a lower impact. The method presented is therefore well suited to the study of cell coupling to probes designed for electrophysiology, and it is poised to contribute to elucidate the nature and mechanism of plasma membrane disruption by micro/nanostructures.

Automatic synthesis of light-processing functions for programmable photonics:theory and realization

Linear light-processing functions(e.g.,routing,splitting,filtering)are key functions requiring configuration to implement on a programmable photonic integrated circuit(PPIC).In recirculating waveguide meshes(which include loop-backs),this is usually done manually.Some previous results describe explorations to perform this task automatically,but their efficiency or applicability is still limited.In this paper,we propose an efficient method that can automatically realize configurations for many light-processing functions on a square-mesh PPIC.At its heart is an automatic differentiation subroutine built upon analytical expressions of scattering matrices that enables gradient descent optimization for functional circuit synthesis.Similar to the state-of-the-art synthesis techniques,our method can realize configurations for a wide range of light-processing functions,and multiple functions on the same PPIC simultaneously.However,we do not need to separate the functions spatially into different subdomains of the mesh,and the resulting optimum can have multiple functions using the same part of the mesh.Furthermore,compared to nongradient-or numerical differentiation-based methods,our proposed approach achieves 3×time reduction in computational cost.

MEMS-based thermoelectric infrared sensors： A review

In the past decade, micro-electromechanical systems （MEMS）-based thermoelectric infrared （IR） sensors have received considerable attention because of the advances in micromachining technology. This paper presents a review of MEMS-based thermoelectric IR sensors. The first part describes the physics of the device and discusses the figures of merit. The second part discusses the sensing materials, thermal isolation micro- structures, absorber designs, and packaging methods for these sensors and provides examples. Moreover, the status of sensor implementation technology is examined from a historical perspective by presenting findings from the early years to the most recent findings.

Structural Characteristics of Allomyrina Dichotoma Beetle＇s Hind Wings for Flapping Wing Micro Air Vehicle

In this study, we present a complete structural analysis ofAllomyrina dichotoma beetle＇s hind wings by investigating their static and dynamic characteristics. The wing was subjected to the static loading to determine its overall flexural stiffness. Dy- namic characteristics such as natural frequency, mode shape, and damping ratio of vibration modes in the operating frequency range were determined using a Bruel ＆ Kjaer fast Fourier transform analyzer along with a laser sensor. The static and dynamic characteristics of natural Allomyrina dichotoma beetle＇s hind wings were compared to those of a fabricated artificial wing. The results indicate that natural frequencies of the natural wing were significantly correlated to the wing surface area density that was defined as the wing mass divided by the hind wing surface area. Moreover, the bending behaviors of the natural wing and artificial wing were similar to that of a cantilever beam. Furthermore, the flexural stiffness of the artificial wing was a little higher than that of the natural one whereas the natural frequency of the natural wing was close to that of the artificial wing. These results provide important information for the biomimetic design of insect-scale artificial wings, with which highly ma- neuverable and efficient micro air vehicles can be designed.

High-resolution 1D moire s as counterfeit security features

A moireis an interference pattern that appears when two different periodic structures are overlaid.The image created is extremely sensitive to small variations in the original layers and is thus very interesting for anti-counterfeit protection.We present a microfabricated 1D moire enabling complex high-resolution patterns as a significantly improved security feature that cannot be reproduced using standard printing methods.Furthermore,we demonstrate,theoretically and experimentally,that a microscopic deviation from the original design results in a macroscopic variation in the moire that is clearly visible to the naked eye.The record resolution achieved in the elements fabricated and the increased design freedom,make these high-resolution moires excellent candidates for a variety of visually appealing security applications.

Thermal scanning probe lithography-a review

Fundamental aspects and state-of-the-art results of thermal scanning probe lithography(t-SPL)are reviewed here.t-SPL is an emerging direct-write nanolithography method with many unique properties which enable original or improved nano-patterning in application fields ranging from quantum technologies to material science.In particular,ultrafast and highly localized thermal processing of surfaces can be achieved through the sharp heated tip in t-SPL to generate high-resolution patterns.We investigate t-SPL as a means of generating three types of material interaction:removal,conversion,and addition.Each of these categories is illustrated with process parameters and application examples,as well as their respective opportunities and challenges.Our intention is to provide a knowledge base of t-SPL capabilities and current limitations and to guide nanoengineers to the best-fitting approach of t-SPL for their challenges in nanofabrication or material science.Many potential applications of nanoscale modifications with thermal probes still wait to be explored,in particular when one can utilize the inherently ultrahigh heating and cooling rates.

Pitching Moment Generation in an Insect-Mimicking Flapping-Wing System

Unlike birds, insects lack control surfaces at the tail and hence most insects modify their wing kinematics to produce control forces or moments while flapping their wings. Change of the flapping angle range is one of the ways to modify wing kinematics, resulting in relocation of the mean Aerodynamic force Center （mean AC） and finally creating control moments. In an attempt to mimic this feature, we developed a flapping-wing system that generates a desired pitching moment during flap- ping-wing motion. The system comprises a flapping mechanism that creates a large and symmetric flapping motion in a pair of wings, a flapping angle change mechanism that modifies the flapping angle range, artificial wings, and a power source. From the measured wing kinematics, we have found that the flapping-wing system can properly modify the flapping angle ranges. The measured pitching moments show that the flapping-wing system generates a pitching moment in a desired direction by shifting the flapping angle range. We also demonstrated that the system can in practice change the longitudinal attitude by generating a nonzero pitching moment.

Design and Demonstration of Insect Mimicking Foldable Artificial Wing Using Four-Bar Linkage Systems

In this work, we develop an artificial foldable wing that mimics the hind wing of a beetle （Allomyrina dichotoma）. In real flight, the beetle unfolds forewings and hind wings, and maintains the unfolded configuration unless it is exhausted. The artificial wing has to be able to maintain a fully unfolded configuration while flapping at a desirable flapping frequency. The artificial foldable hind wing developed in this work is based on two four-bar linkages which adapt the behaviors of the beetle＇s hind wing. The four-bar-linkages are designed to mimic rotational motion of the wing base and the vein folding/unfolding motion of the beetle＇s hind wing. The behavior of the artificial wings, which are installed in a flapping-wing system, is observed using a high-speed camera. The observation shows that the wing could maintain a fully unfolded configuration during flapping motion. A series of thrust measurements are also conducted to estimate the force generated by the flapping-wing system with foldable artificial wings. Although the artificial foldable wings give added burden to the flapping-wing system because of its weight, the thrust measurement results show that the flapping-wing system could still generate reasonable thrust.

An artificial lateral line system using IPMC sensor arrays

Most fish and aquatic amphibians use the lateral line system,consisting of arrays of hair-like neuromasts,as an important sensory organ for prey/predator detection,communication,and navigation.In this paper a novel bio-inspired artificial lateral line system is proposed for underwater robots and vehicles by exploiting the inherent sensing capability of ionic polymer-metal composites(IPMCs).Analogous to its biological counterpart,the IPMC-based lateral line processes the sensor signals through a neural network.The effectiveness of the proposed lateral line is validated experimentally in the localization of a dipole source(vibrating sphere)underwater.In particular,as a proof of concept,a prototype with body length(BL)of 10 cm,comprising six millimeter-scale IPMC sensors,is constructed and tested.Experimental results have shown that the IPMC-based lateral line can localize the source from 1-2 BLs away,with a maximum localization error of 0.3 cm,when the data for training the neural network are collected from a grid of 2 cm by 2 cm lattices.The effect of the number of sensors on the localization accuracy has also been examined.

Progress in Silicon Nanowire-Based Field-Effect Transistor Biosensors for Label-Free Detection of DNA

Silicon nanowire （SiNW）, as one-dimensional semiconducting nanomaterial, has been incorporated into the filed-effect transistor （FET） devices to increase the efficacy and signal-to-noise in DNA sensing applications. Due to the advantages of high sensitivity, excellent selectivity, label-free detection, direct electrical readout, and minia- turization, SiNW FET-based DNA sensors have been regarded as an important tool in applications of molecular di- agnostics, DNA sequencing, gene expressions, and drug discovery. Here, we review the recent progress in SiNW- FET sensors for label-free electrical DNA detection. We first introduce the working principle of SiNW-FET DNA sensors, SiNW fabrication technologies, bio-functionalization on nanowire surface, and enhancement of device sen- sitivity. Then we sum up the applications of SiNW sensors in detection of DNA hybridization, infectious viruses, microRNA, genetic change （DNA mutation, DNA methylation, and DNA repair）, and protein-DNA interactions. We address several crucial points of sensing performance including sensitivity, selectivity, and limit of detection. Finally, the perspectives, challenges, and some solutions of the field are also discussed.

Simultaneously controlling heat conduction and infrared absorption with a textured dielectric film to enhance the performance of thermopiles

The heat conduction and infrared absorption properties of the dielectric film have a great influence on the thermopile performance.Thinning the dielectric film,reducing its contact area with the silicon substrate,or adding high-absorptivity nano materials has been proven to be effective in improving thermopiles.However,these methods may result in a decrease in the structural mechanical strength and in creases in the fabrication complexity and cost.In this work,a new performa nce-enha ncement strategy for thermopiles by simultaneously con trolling the heat conduction and infrared absorption with a TExtured Dielectric(TEDI)film is developed and presented.The TEDI film is formed in situ by a simple hard-molding process that is compatible with the fabrication of traditional thermopiles.Compared to the control FLat Dielectric(FLDI)film,the intrinsic thermal conductance of the TEDI film can be reduced by〜18-30%,while the in fra red absorptio n can be increased by-7-13%.Corresp on dingly,the responsivity and detectivity of the fabricated TEDI film-based thermopile can be significantly enhanced by〜38-64%.An optimized TEDI film-based thermopile has achieved a responsivity of 156.89 V-W_1 and a detectivity of 2.16×10^(8)cm-Hz^(1/2)·W^(-1),while the response time constant can remain<12 ms.These results exhibit the great potential of using this strategy to develop high-performance thermopiles and enhance other sensors with heat transfer and/or infrared absorption mechanisms.

Recent progress in silk fibroin-based flexible electronics

With the rapid development of the Internet of Things(loT)and the emergence of 5G,traditional silicon-based electronics no Ion ger fully meet market dema nds such as nonplanar application scenarios due to mechanical mismatch.This provides unprecedented opportunities for flexible electronics that bypass the physical rigidity through the introduction of flexible materials.In recent decades,biological materials with outstanding biocompatibility and biodegradability,which are considered some of the most promising candidates for next-generation flexible electronics,have received increasing attention,e.g.,silk fibroin,cellulose,pectin,chitosan,and melanin.Among them,silk fibroin presents greater superiorities in biocompatibility and biodegradability,and moreover,it also possesses a variety of attractive properties,such as adjustable water solubility,remarkable optical transmittance,high mechanical robustness,light weight,and ease of processing,which are partially or even completely lacking in other biological materials.Therefore,silk fibroin has been widely used as fundamental components for the construction of biocompatible flexible electronics,particularly for wearable and implantable devices.Furthermore,in recent years,more attention has been paid to the investigation of the functional characteristics of silk fibroin;such as the dielectric properties,piezoelectric properties,strong ability to lose electrons,and sensitivity to environmental variables.Here,this paper not only reviews the preparation technologies for various forms of silk fibroin and the recent progress in the use of silk fibroin as a fundamental material but also focuses on the recent advaneed works in which silk fibroin serves as functional components.Additi on ally,the challenges and future development of silk fibroin-based flexible electronics are summarized.