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Electrospinning (ES) methods that can produce piezoelectricity in polymer nanofibers have attracted tremendous research attention. These electrospun polymer nanofibers can be employed for sensors, energy harvesting, tissue engineering, and filtration applications. This paper reviews the performance of a variety of electrospun piezoelectric polymer nanofibers produced by different ES methods, including near‐field electrospinning and conventional far‐field electrospinning methods. Herein, it is described how the ES method can affect the piezoelectric properties of various polymer nanofibers, including poly(vinylidene difluorine), poly(vinylidene fluoride‐trifluoroethylene), nylon 11, poly(l‐lactic acid), and poly(α‐benzyl‐l‐glutamate). Due to the varied matrix structures of piezoelectric polymer nanofibers, the ES method may conduct variable effects on the piezoelectric properties of polymer nanofibers. After characterizations by X‐ray diffraction, Fourier transform infrared spectrum, dielectric spectra, and piezoelectric coefficient measurements, it is found that the piezoelectric properties of the polymer nanofibers can be significantly affected by the ES parameters. Most of previous review articles focus on the output performance of electrospun polymer nanofibers. A detailed description of how different ES methods affect the piezoelectricity of polymer nanofibers is still lacking. In this review paper, the basic principle behind ES methods and the way in which different ES methods affect the properties of polymer nanofibers are examined. [ABSTRACT FROM AUTHOR]

Recently, flexible pressure and strain sensors have attracted the attention of researchers because of their high sensitivity, broad strain-sensing ability, and various forms. Flexible sensors have essential applications and broad market prospects in fields such as wearable electronics, intelligent machines, and structural health monitoring. At the same time, these emerging fields also require more significant performance requirements for flexible sensors. Conductive rubber composite materials have high tensile strength, high electromechanical sensitivity, and high stability, making them ideal for fabricating of high-performance flexible pressure sensors. Therefore, further improving the performance of conductive flexible rubber composite pressure sensors is developmental focus. In this review, the preparation and electromechanical response mechanisms of conductive polymer composites are summarized, and methods for improving the performance of flexible sensors through structural design are introduced, including conductive network structural design, substrate structural design, and conductive polymer composite structural design. In addition, the main applications of flexible pressure sensors are introduced. Finally, problems in developing flexible sensors are summarized, and future development directions are discussed. [ABSTRACT FROM AUTHOR]

Herein, we report for the first time cost-effective synthesis of lanthanum doped cobalt-iron ferrite composite sensors towards the detection of liquified petroleum gas (LPG) at room temperature. The synthesized ferrite composites were characterized by different analytical techniques such as scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and ultraviolet–visible (UV–Vis) spectroscopy methods to analyse the surface morphology, elemental composition, functional groups, structural and optical properties. The synthesized ferrite composite exhibit improved ac conductivity and dielectric attributes due to the doping of rare earth (RE) lanthanum NPs into the cobalt-iron ferrites. Doping of lanthanum nanoparticle (NPs) into cobalt-iron ferrites result into porous surface with interconnected network which support for easy transportation of charge carriers into neighbouring sites. The gas sensing response of the lanthanum doped cobalt-iron ferrites was carried out at room temperature. The gas sensing properties of the synthesized CoFe 2-x La x O 4 samples were studied for LPG, ethane, propane, butane, methane, and petrol vapours of variable hydrocarbon gas species. The CoFe 2-x La x O 4 composite shows superior gas response towards LPG gas at room temperature. The gas response of CoFe 2-x La x O 4 (x -0.1) composite sample was measured to be nearly 98% for LPG with enhanced response and recovery times. Furthermore, the long-term stability of these gas sensor towards LPG indicates that, that among the synthesized samples x - 0.1 composite samples show stable performance even after 60 days of operation. Owing to improved electrical conductivity, gas sensing behaviour and quick response and recovery times at room temperature, these CoFe 2-x La x O 4 composites could be employed as suitable candidate towards fabrication of room temperature gas sensors especially for the detection of LPG at low concentration (ppb level). [ABSTRACT FROM AUTHOR]

Organic triboluminescent (TL) crystals have attracted significant attention in recent years for their potential applications in various fields such as damage sensing in aerospace structures, cyanide detection in water, and radiation sensing. Europium tetrakis dibenzoylmethide triethylammonium (EuD4TEA) is a class of organic TL crystals that have shown promising results in terms of sensitivity due to their high TL intensity, however, they exhibit thermal instability and fragility concerns. In this review, recent research progress on the development, characterizations, TL properties, and potential applications of EuD4TEA crystals in various fields, are summarized. The review will conclude with the current challenges of EuD4TEA crystals, such as fragility nature, thermal instability, and increasing cost of europium. Despite having challenges, EuD4TEA crystals have the potential for damage sensing in the structural composite. [ABSTRACT FROM AUTHOR]

The resolution of a quartz crystal microbalance (QCM) is particularly crucial for gas sensor applications where low concentrations are detected. This resolution can be improved by increasing the effective surface of QCM electrodes and, thereby, enhancing their sensitivity. For this purpose, various researchers have investigated the use of micro-structured materials with promising results. Herein, we propose the use of easy-to-manufacture metal blacks that are highly structured even on a nanoscale level and thus provide more bonding sites for gas analytes. Two different black metals with thicknesses of 280 nm, black aluminum (B-Al) and black gold (B-Au), were deposited onto the sensor surface to improve the sensitivity following the Sauerbrey equation. Both layers present a high surface roughness due to their cauliflower morphology structure. A high response (i.e., resonant frequency shift) of these QCM sensors coated with a black metal layer was obtained. Two gaseous analytes, H2O vapor and EtOH vapor, at different concentrations, are tested, and a distinct improvement of sensitivity is observed for the QCM sensors coated with a black metal layer compared to the blank ones, without strong side effects on resonance frequency stability or mechanical quality factor. An approximately 10 times higher sensitivity to EtOH gas is reported for the QCM coated with a black gold layer compared to the blank QCM sensor. [ABSTRACT FROM AUTHOR]

Polyethylene terephthalate (PET) thermoplastic polyester is durable, formable material that is widely used to manufacture consumer products like sailcloth, sailing spinnakers, food-grade containers, etc. for commercial and engineering applications. The recycling of PET is still a challenge because of its abundance, especially in low-income/developing countries. The present study reports the recycling of PET by utilizing the primary (1°) recycled PET (R-PET) for 3D printing-based sensor applications with the idea of converting waste to wealth. The investigations were performed on PET-based waste collected from institute campus canteens (in form of used food containers/soft drink bottles) after ascertaining their rheological, mechanical, morphological, bonding, and sensing capabilities. The sensing capabilities of R-PET were explored by performing a ring resonator test of a 3D-printed substrate using a vector network analyzer (VNA). The result of the study outlined that R-PET-based sensors may be used in sailcloth, and sailing spinnakers to monitor the location of boats in a shipyard/dock. [ABSTRACT FROM AUTHOR]

Available wearable dosimeters suffer from spectral mismatch during the measurement of broadband UV and visible radiation in environments that receive radiation from multiple sources emitting differing spectra. We observed this type of multi-spectra environment in all five Washington State cannabis farms visited during a field study investigating worker exposure to ultraviolet radiation in 2018. Spectroradiometers do not suffer from spectral mismatch in these environments, however, an extensive literature review conducted at the time of writing did not identify any spectroradiometers that were directly deployable as wearable dosimetry devices. To close this research gap, we developed a microcontroller system and platform that allows for researchers to mount and deploy the Ocean Insight Flame-S Spectroradiometer as a wearable device for measurement of UV and visible wavelengths (300 to 700 nm). The platform validation consisted of comparing measurements taken under platform control with measurements taken with the spectrometer controlled by a personal computer running the software provided by the spectroradiometer manufacturer. Three Mann–Whitney U-Tests (two-tailed, 95% CI), one for each intensity condition, compared the central tendency between the total spectral power (TSP), the integral of a spectrum measurement, measured under both control schemas. An additional analysis of per pixel agreement and overall platform stability was performed. The three Mann–Whitney tests returned no significant difference between the set of TSPs for each filter condition. These results suggest that the spectroradiometer takes measurements of equivalent accuracy under both control schemas, and can be deployed as a wearable device for the measurement of wavelength resolved UV and visible radiation. [ABSTRACT FROM AUTHOR]

Electronics and soft robotics demand the development of a new generation of hybrid materials featuring novel properties. Among these, remarkable mechanical properties are required to sustain mechanical stresses, and electrical and magnetic properties are essential to design the devices' interface. In this study, a hybrid material is presented, consisting of a spider silk thread, providing mechanical robustness, coated with a layer of a magnetostrictive FeCo alloy, which ensures both electrical conductivity and stress‐sensitive magnetic properties. The durability and the homogeneity of the composite are validated, as well as its ability to respond to magnetic and mechanical stimuli. Despite the coating, the soft nature of the silk and its mechanical performances are preserved. The magnetic study reveals that the magnetic behavior of the film is strongly affected by the silk thread–FeCo layer interaction, especially under mechanical stresses. Indeed, when the composite is subjected to tensile strain, the magnetic signal changes accordingly, indicating that the layer–silk interaction is maintained and can be exploited to reveal the tensional state of the sample even under severe cycles. Therefore, the presented hybrid material is a flexible fiber with properties that are suitable for magneto‐electronics applications, e.g., magnetic actuators as well as strain/stress sensors. [ABSTRACT FROM AUTHOR]

One‐dimensional sensing materials that are prepared via electrospinning and controlled annealing exhibit intrinsic properties, such as electron transmissivity, magnetic susceptibility, specific heat capacity, as well as optical and mechanical characteristics. Particularly, the electronic transmission characteristics of the ceramic fiber materials, such as the electrical conductivity, photocurrent, magnetoresistance, nanocontact resistance, and dielectric properties, exhibited great potential for applications in the next generation of electronic sensing devices. First, electrospun ceramic materials with different structural and functional characteristics were reviewed here, after which the strategies for improving their properties, as well as the method for assembling the flexible devices, are summarized. Moreover, the electrospun ceramic nanofibers were detailedly discussed regarding applications in device construction and wearable electronics, such as photosensors, gas sensors, mechanical sensors, and other energy storage devices. Finally, the future development direction of the electrospinning technology for multifunctional and wearable electronics skin was proposed. [ABSTRACT FROM AUTHOR]

Most electrical sensor and biosensor elements require reliable transducing elements to convert small potential changes into easy to read out current signals. Offering inherent signal magnification and being operable in many relevant environments field‐effect transistors (FETs) are the element of choice in many cases. In particular, using electrolyte gating, numerous sensors and biosensors have been realized in aqueous environments. Over the past years, electrolyte‐gated FETs have been fabricated using a variety of semiconducting materials, including graphene, ZnO, as well as conjugated molecules and polymers. Above all, using conducting polymers top‐performing devices have been achieved. Herein, an approach to use a transition metal dichalcogenide (TMDC)‐based monolayer device as a transducing element is presented. Using MoS2 monolayers, it is shown that such electrolyte‐gated devices may be regarded as very promising transducing elements for sensor and biosensor applications, enabled by their high sensitivity for environmental changes and the possibility of using the naturally occurring sulfur vacancies as grafting points of biorecognition layers. Furthermore, the behavior of such a device under prolonged operation in a dilute biologically relevant electrolyte such as phosphate buffered saline solution (PBS) is reported. [ABSTRACT FROM AUTHOR]

Robotic devices for nursing care are expected to help caregivers work with the elderly. Some robotic devices assist in the physical transfer of the elderly, and these robots come in contact with large surfaces of the human body. The regions of the buttock and the back may be uncomfortable due to the surface material or motions of the robotic devices. Therefore, sensing devices simulating a human body were developed to quantify and evaluate the load of a human body objectively. This simulated buttock consists of simulated bone and soft tissues, which include muscle, fat and skin. These regions have multi-axis force sensors to enable the quantification of the load due to the robotic devices used for nursing care. On measuring the soft exterior, it was found that the stiffness of the buttock dummy was similar to the human buttock. The comfort of a robotic bed was measured using the simulated buttock, and it was found that the shear force increased due to the deformation of the robotic bed. Thus, it was proven that the simulated buttock was capable of measuring the load of the human body when being used with robotic devices for nursing care. [ABSTRACT FROM AUTHOR]

In the present study, a Schiff base (E)-2-[(3,5-bis(trifluoromethyl)phenylimino)methyl]-4,6-dichlorophenol has been synthesized. Its spectroscopic and X-ray single-crystal data have been compared with the results of theoretical calculations based on the DFT method, as well as molecular electrostatic potential (MEP), HOMO and LUMO, and nonlinear optical (NLO) effects. Antimicrobial activity of the compound has been tested against some bacteria and fungi. According to UV-Vis and agarose gel electrophoresis methods, the compound interacts with DNA electrostatically and breaks it oxidatively. Antioxidant activity of the compound measured by the DPPH method, is lower than that of BHT. [ABSTRACT FROM AUTHOR]

Graphical abstract The Au@WO 3 -SnO 2 nanofibers with well-dispersed tungsten species, exhibit excellent sensing performance, even at parts per billion level concentrations of gases. Highlights • We studied the synthesis and sensing performance of Au@WO 3 -SnO 2 nanofibers. • The Au@WO 3 -SnO 2 nanofibers were fabricated through psHT treatment. • The gas sensor showed excellent sensing response of 79.6 to 0.5 ppm acetone. • The sensor also exhibited outstanding gas-sensing selectivity and stability. Abstract The design of one-dimensional semiconductor metal oxides (SMOs) with porous structure has attracted tremendous attention owing to their larger specific surface area and a greater number of surface-active sites. Herein, Au@WO 3 -SnO 2 nanofibers were fabricated through post-synthetic hydrothermal treatment which employed self-assembly A-stage phenolic resin as a sacrificial template. The nanopores observed in the Au@WO 3 -SnO 2 nanofibers had diameters of about 3.5 nm. The nanoporous WO 3 -SnO 2 nanofibers with well-dispersed tungsten species, exhibit excellent sensing performance, even at parts per billion level concentrations of gases. In a comparison with Au@SnO 2 sample, the Au@WO 3 -SnO 2 nanofibers exhibited a five times higher response (S = 79.6) to 0.5 ppm acetone at 150 °C and a good acetone selectivity. Furthermore, the Au@WO 3 -SnO 2 nanofibers-based sensor also possessed good long-term stability. The extraordinary sensing performance can be attributed to the porous structure, highly one-dimensional interconnection, larger specific surface area, and WO 3 /SnO 2 heterostructure. The approach proposed for functionalized WO 3 -SnO 2 nanofibers in this work may contribute to the potential application in human health breath analysis by non-invasive detection. [ABSTRACT FROM AUTHOR]

Abstract Herein, we successfully developed a novel three-dimensional framework attached carbon nanotubes deposited with high density of gold nanoparticles (Au NPs-CNTs/3DF) through a facile method. The achieved hybrid with an opened hierarchical network was effectively used as a free-standing sensor for hydrazine detection. The catalytic activity of the proposed sensor was impressively higher than those of other surveyed materials, such as CNTs/3DF and Au NPs/3DF. In this regard, the much higher intensity of oxidation current density and negative peak potential were presented for Au NPs-CNTs/3DF towards hydrazine oxidation. Through amperometric measurements, the Au NPs-CNTs/3DF electrode displayed excellent performance for hydrazine determination with wide linear detection range of 0.5 to 483 μM, high sensitivity of 1.65 μA·μM−1·cm−2, a low detection limit of 1.1 μM, along with negligible interference effect. The obtained results suggest that the Au NPs-CNTs/3DF hybrid holds the great prospect for highly sensitive and selective determination of hydrazine in practical applications. Graphical abstract Unlabelled Image Highlights • A novel sensor of CNTs/3DF deposited with Au NPs was prepared by a facile method. • The 3D hierarchical mesoporous network improved active sites and conductivity. • The sensor detected hydrazine with low LOD of 1.1 μM. • The sensor detected hydrazine with wide linear detection range of 0.5–483 μM. • The sensor showed stability and accurate detection of hydrazine in real samples. [ABSTRACT FROM AUTHOR]

BACKGROUND: Electrospinning is a highly effective method in order to generate nano-scaled fibers. In conventional electrospinning technique, geometry of nanofibers are mostly random due to the chaotic behavior of polymer jet. OBJECTIVE: Purpose of this study is to produce aligned nanofibers from PVP polymers with advanced electrospinning technique in order to be used in a potential novel sensor applications, tissue regeneration and engineering. METHODS: In this study, by using finite hollow cylinder focusing electrodes, an external electrostatic field is created. With these electrodes, it is aimed to decrease whipping instability of polymer jet. In addition, it is also investigated that the alignment ratio of nanofibers by using conductive parallel electrodes which placed through jet trajectory. RESULTS: In conclusion, with the effect of electrical field created by cylinder electrodes, radius of the fiber dispersion on the collector was able to be reduced and aligned nanofibers were successfully produced by using electrical field generated from the parallel plates. CONCLUSIONS: Radius of the fiber dispersion on the collector is 9.95 mm and fiber diameters varied between 800 nm and 3 μm. Additionally, alignment ratio of the fibers is determined with ImageJ software. These alignment of nanofibers can be used in tissue engineering applications and sensor applications. [ABSTRACT FROM AUTHOR]

Abstract: A resonator based metamaterial for sensor application is studied in this paper. The resonator is encompassed by a partial ground plane and excited by a microstrip feed‐line. As the resonator, partial ground frame, and the feeding transmission line are on the same microstrip, the measurement can be executed by using the common laboratory facility instead of using the waveguide. The proposed metamaterial occupies a compact size of 20 × 20 mm2 and is imprinted on a low‐cost FR4 substrate. The substrate has a relative permittivity of 4.6 with a dielectric loss tangent of 0.02. The resonator and the ground frame are placed on the similar part of the substrate and the feed‐line is placed on the other part of the substrate. In metamaterial design, normally arrays of metamaterial unit cells are needed, whereas this study presents only one cell, which can achieve the metamaterial properties. The characteristic parameters are fetched and analyzed to find the concurrency between the simulated and measured results. The presented metamaterial is applied in sensor applications where the simulated and measured results reveal considerable agreement. [ABSTRACT FROM AUTHOR]

The magnetic properties of amorphous glass coated microwires are determined mainly by the distribution of residual quenching stresses over the microwire cross section. In this paper a control of the residual quenching stresses in amorphous ferromagnetic microwires is achieved by changing the microwire glass shell thickness by etching. To this end, a special gel is synthesized for precision glass shell etching of series of Co-rich microwires. The use of the gel provides a possibility of uniform etching of the microwire glass coating at a rate of 0.2–3.2 μm/h depending on the amount of glass already removed, a surface roughness being about 40–100 nm. It is also possible to completely remove the glass shell of the microwire without damage its metallic nucleus. The small angle magnetization rotation method has been used to determine the change in the amplitude of the residual quenching stress with a gradual decrease of the glass shell thickness of microwires of composition Co 67 Fe 4 Ni 2 Mo 2 B 11 Si 14 and Co 71 Fe 4 Si 10 B 15 . It is found that the amplitude of the residual quenching stress deceases by 40–50% in average after removing of the layer of 1 μm thickness from the glass coating. [ABSTRACT FROM AUTHOR]

HfCo thin films (in the atomic weight range of x = 30-36) were growth on Si (100) substrates by direct current (DC) magnetron sputtering method. Thin films produced with atomic compositions in this context depicted the amorphous structure. The films revealed soft magnetic properties and thus exhibited very low hysteresis along the hard-axis direction. Magnetic measurements indicated that HfCo thin film has the maximum saturation magnetization (1491 emu cm) at 300 K. Additionally, magnetization measurements show an increase in saturation magnetization value from 981 to 1491 emu cm when the value of x varies between 30 and 35. The influence of varying sputtering pressure and film composition on soft magnetic properties are investigated and discussed in the present paper. [ABSTRACT FROM AUTHOR]

Functionalized graphene oxide (fGO) was synthesized and subsequently used for synthesis of nanocomposite with polypyrrole (PPy) and chitosan (CS) to give fGO-PPy-CS nanocomposites. Screen-printed carbon electrodes were then modified with these nanocomposites to construct an unprecedented hydrogen peroxide (HO) sensor. Cyclic voltammetry (CV) and amperometric response demonstrated that the composite materials hold potential for electrocataytic reduction towards HO. Under optimal experimental conditions, the amperometric response of the fGO-PPy-CS sensor was linearly proportional to HO in the range of 2.5-200 μM with a detection limit of 1.95 μM (S/ N = 3). The present study provides new opportunities for fGO-PPy-CS-modified electrodes to probe the improved non-enzymatic detection of HO. It further broadens the applications of graphene-based conducting composites in the field of sensors and biosensors for diverse applications. [ABSTRACT FROM AUTHOR]

The whole set of geometrical, mechanical and magnetic parameters of Co-rich amorphous ferromagnetic microwires very promising for the development of sensitive stress and Giant Magneto-Impedance sensors have been determined by means of scanning electron microscopy, selective nanoindentation and small angle magnetization rotation method. The magnetostriction constants obtained are sensitive to the true microwire compositions. The experimentally estimated amplitudes of the residual quenching stress are mainly determined by the ratio of the inner and outer wire diameters. They are found to be in good correspondence with the theoretical values calculated based on the theory of viscoelasticity. [ABSTRACT FROM AUTHOR]

Time-reversed lasing in a uniform slab and a grating structure are investigated in the terahertz range. The results show that both the uniform slab and grating can support terahertz time-reversed lasing. Nevertheless, due to the tunable effective refractive index, the grating structure can not only exhibit time-reversed lasing more effectively and flexibly than a uniform slab, but also can realize significant absorption in a broader operating frequency range. Furthermore, applications of terahertz time-reversed lasing for novel concentration/thickness sensors are preliminarily studied in a single-channel coherent perfect absorber system. [ABSTRACT FROM AUTHOR]

Graphene plasmonics has been introduced as a novel platform to design various nano- and microstructures to function in a wide range of spectrum from optical to THz frequencies. Herein, we propose a tunable plasmonic metamaterial in the THz regime by using metallic (silver) concentric microscale split ring resonator arrays on a multilayer metasurface composed of silica and silicon layers. We obtained an absorption percentage of 47.9% including two strong Fano resonant dips in THz regime for the purely plasmonic metamaterial without graphene layer. Considering the data of an atomic graphene sheet (with the thickness of ~0.35 nm) in both analytical and experimental regimes obtained by prior works, we employed a graphene layer under concentric split ring resonator arrays and above the multilayer metasurface to enhance the absorption ratio in THz bandwidth. Our numerical and analytical results proved that the presence of a thin graphene layer enhances the absorption coefficient of MM to 64.35%, at the highest peak in absorption profile that corresponds to the Fano dip position. We also have shown that changing the intrinsic characteristics of graphene sheet leads to shifts in the position of Fano dips and variations in the absorption efficiency. The maximum percentage of absorption (~67%) was obtained for graphene-based MM with graphene layer with dissipative loss factor of 1477 Ω. Employing the antisymmetric feature of the split ring resonators, the proposed graphene-based metamaterial with strong polarization dependency is highly sensitive to the polarization angle of the incident THz beam. [ABSTRACT FROM AUTHOR]

It can be seen that optical fibre sensing technology has huge potential to address industrial applications. They offer various advantages over the conventional electrical systems and are increasingly becoming cost effective. Different types of fibre structure and configurations can be utilised to tailor specific applications. The paper aims to highlight the developments in optical fibre sensors for industrial applications. [ABSTRACT FROM AUTHOR]

Inductive Loop Detectors (ILDs) are the most commonly used sensors in traffic management systems. This paper shows that some spectral features extracted from the Fourier Transform (FT) of inductive signatures do not depend on the vehicle speed. Such a property is used to propose a novel method for vehicle classification based on only one signature acquired from a sensor single-loop, in contrast to standard methods using two sensor loops. Our proposal will be evaluated by means of real inductive signatures captured with our hardware prototype. [ABSTRACT FROM AUTHOR]

The amplitude of the second harmonic of the electro-motive force occurring in the receiving pick-up coil when alternating electrical current is flowing through the microwire is measured as a function of applied external magnetic field, at different mechanical tensile stresses. In addition, an analytical expression for the amplitude of the second harmonic of the electro-motive force is derived. Comparing the experimental and theoretical data the saturation magnetization, the magnetostriction constant and the amplitude of the residual quenching stress have been determined for a family of Co-rich glass-coated microwires. [ABSTRACT FROM AUTHOR]

Most of the variables measured in scientific investigations or engineering applications depend, by varying degrees, on temperature. This necessitates the simultaneous measurement of temperature along with the variable of interest in order to perform high fidelity temperature compensated measurements. Silicon diode based temperature sensors (or silicon thermodiodes) have the advantages of being low cost, having an absolute temperature measurement capability as well as providing the option of on-chip integration with electronic circuits and a wide temperature measurement range. Leveraging these advantages, engineers and scientists have used silicon thermodiodes in numerous and diverse applications. This paper identifies the common temperature measuring techniques, and focuses on the use and advantages offered by silicon diodes operated as temperature sensors in different drive modes. Finally it explores the published literature for summarizing the application areas where such sensors have been utilized successfully in recent years. [ABSTRACT FROM AUTHOR]

A novel compact plasma sensor applicable for the supervision and control of industrial plasma processes is presented in this contribution. Based on the multipole resonance probe (MRP), the new planar MRP (pMRP) is introduced as a powerful and economical monitoring tool, flush-mounted into the reactor wall. Hence, it can be used for an effective suppression of disturbances of the plasma process itself. Using 3D electromagnetic field simulations with CST Microwave Studio, the pMRP is investigated and challenges as well as prospects of the new sensor design are discussed in detail. Three different sensor versions are presented and compared with the resonance behavior of the MRP. Furthermore, limitations concerning position tolerances are shown and the suitability of the pMRP is proven. Measurements in a double inductive coupled plasma, with argon as process gas and varying excitation powers, demonstrate the suitability of the pMRP for monitoring purposes. [ABSTRACT FROM PUBLISHER]

This article discusses the experiences from the development and deployment of two image-based environmental monitoring sensor applications using an embedded wireless sensor network. Our system uses low-power image sensors and the Tenet general purpose sensing system for tiered embedded wireless sensor networks. It leverages Tenet's built-in support for reliable delivery of high rate sensing data, scalability and its flexible scripting language, which enables mote-side image compression and the ease of deployment. Our first deployment of a pitfall trap monitoring application at the James San Jacinto Mountain Reserve provided us with insights and lessons learned into the deployment of and compression schemes for these embedded wireless imaging systems. Our three month-long deployment of a bird nest monitoring application resulted in over 100,000 images collected from a 19-camera node network deployed over an area of 0.05 square miles, despite highly variable environmental conditions. Our biologists found the on-line, near-real-time access to images to be useful for obtaining data on answering their biological questions. [ABSTRACT FROM AUTHOR]

We report here on a comprehensive study of an alternatingcurrent Joule annealing (ACJA) method for optimizing the giant magnetoimpedance (GMI) effect of Co-rich amorphous wires for sensor applications. Experimental results indicated that the proper ACJA treatment can drastically improve the GMI property of as-cast wire. At 10 MHz, the maximum GMI ratio [ΔZ/Z0]max of ACJA-ed wire increase to 205.38%, which is nearly 3.3 times that of 62.84% for as-cast wire, and the maxima field response sensitivity ξmax of ACJA-ed wire increases to 345.90%/Oe by more than twice that of 170.92%/Oe for as-cast wire. With an increase of AC amplitude, a remarkable dependence of GMI performance appears on the microstructural evolution such as the structural relaxation, the degree of local order, as well as circular magnetic domains. Importantly, the atomic order orientation incorporating HRTEM observation and circumferential permeability were effectively increased by the co-action of thermal activation energy and magnetic field energy during ACJA, further to enhance the magnetic properties to some extent. Based on both the numerical calculation of transient temperature rise and GMI behavior, we propose ACJA as an efficient annealing technique to achieve simultaneous best performance of [ΔZ/Z0]max and ξmax for potentially magnetic sensor applications in detecting weak magnetic fields. [ABSTRACT FROM AUTHOR]

Abstract: This letter reports on the high-frequency giant magnetoimpedance (GMI) effect in a LC-resonator built on a glass-coated Co83.2B3.3Si5.9Mn7.6 microwire with two cylindrical electrodes at the ends of the microwire. In the investigated frequency range of 100–1000MHz, the shape of GMI curves varies drastically as the frequency increases. It has been demonstrated that the resonance in a glass-coated microwire LC-resonator occurs at a specific intensity of the applied dc magnetic field. The sudden changes of the phase angle as large as 180° evidence the occurrence of the resonance. The GMI features in a LC-resonator originate from both the permeability changes of the microwire and the LC-resonance of the circuit. More interestingly, extremely large increases of GMI in the vicinity region of the resonant frequency (∼890MHz) are also observed. The maximum GMI response up to 10,000% has been found at the frequency of 889.41MHz. This result is very beneficial for developing a new family of high-frequency and ultra-sensitive GMI-based magnetic sensor applications. [Copyright &y& Elsevier]

Abstract: A novel magnetic LC-resonator for micromagnetic sensor devices was fabricated by means of microelectromechanical system (MEMS) technique. The micro-LC-resonator consists of a solenoidal microinductor with a bundle of annealed soft magnetic Co83.2B3.3Si5.9Mn7.6 microwires as microcore and a capacitor connected in parallel to the microinductor. The dimensions of solenoidal microinductors fabricated by MEMS technique were 500–1000μm in length with 10–20 turns. Because the permeability of the microcore is changing rapidly as a function of external magnetic field, the inductance of the microinductors can change drastically according to the external magnetic field. Therefore, the resonance frequency as well as the impedance of a micro-LC-resonator can be sensitively altered as the external magnetic field changes. The maximum magnetoimpedance ratio value for a micro-LC-resonator was reached as much as 500%. The impedance change of the LC-resonator can be greatly enhanced by selecting operating frequencies at near the resonance frequency. [Copyright &y& Elsevier]

As solar power becomes more important, sunshine duration has become a critical variate for meteorological observations and research. In this review, the evolution of the operation principle and construction of sunshine recorders was summarized. Sunshine recorders were classified according to their measurement methods, and their historical and technological development were reviewed. Characters, such as thresholds, uncertainties, maintenance, and operational cost of different sunshine recorders, are compared. Then, the advantages and disadvantages of each measurement method and the sensors applied to the sunshine recorders were also discussed. At the end of the paper, we concluded that photoelectric sunshine recorder is currently the best option for sunshine duration measurement due to high-precision and low cost, and the thermoelectric sunshine recorder has the potential to dominate the sunshine duration measurement market for their wide spectral response range. The pyrheliometric and pyranometric methods are the mainstream for designing recorders in the future period. [ABSTRACT FROM AUTHOR]

A moisture sensor based on a composite resonator is used to measure different honey samples, which include imitation honey. The sensor changes its frequency response in accordance with the dielectric permittivity that it detects in the measured samples. Although reflectometry sensors have been used to measure the percentage of moisture in honey for almost a century, counterfeiters have achieved that their apocryphal product is capable of deceiving these kinds of sensors. Metamaterial features of the composite resonators are expected to improve their response when detecting lossy samples such as organic samples. It is also sought that these sensors manage to detect small differences not only in the real parts of the dielectric permitivities of samples but also in their imaginary parts, and, thus, the sensors are able to discern between real honey and slightly altered honey. Effectively, not only was it possible to improve the response of the sensors by using lossy samples but it was also possible to identify counterfeit honey. [ABSTRACT FROM AUTHOR]

This article presents a compact microstrip meander-line antenna for sensor network applications in the 290 MHz band. The antenna is fed by coplanar waveguide and its dimension is 15 mm × 15 mm × 2 mm. Because of the use of a very high relative permittivity substrate (ℇr = 90) and meander-line structure simultaneously, the side length of the designed antenna is about λg/12 (λg is the guided wavelength) so that the circuit size is reduced greatly. Measurements verify that the proposed antenna has bandwidth of 12% at the resonant frequency of 293 MHz. Also, the radiation patterns measured at resonance frequencies are very close to omnidirectional in the E-plane. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2438–2440, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22798 [ABSTRACT FROM AUTHOR]

According to the National Institute of Deafness and other Communication Disorders 2012 report, the number of cochlear implant (CI) users is steadily increasing from 324,000 CI users worldwide. The cochlea, located in the inner ear, is a snail-like structure that exhibits a tonotopic geometry where acoustic waves are filtered spatially according to frequency. Throughout the cochlea, there exist hair cells that transduce sensed acoustic waves into an electrical signal that is carried by the auditory nerve to ultimately reach the auditory cortex of the brain. A cochlear implant bridges the gap if non-functional hair cells are present. Conventional CIs directly inject an electrical current into surrounding tissue via an implanted electrode array and exploit the frequency-to-place mapping of the cochlea. However, the current is dispersed in perilymph, a conductive bodily fluid within the cochlea, causing a spread of excitation. Magnetic fields are more impervious to the effects of the cochlear environment due to the material properties of perilymph and surrounding tissue, demonstrating potential to improve precision. As an alternative to conventional CI electrodes, the development and miniaturization of microcoils intended for micromagnetic stimulation of intracochlear neural elements is described. As a step toward realizing a microcoil array sized for cochlear implantation, human-sized coils were prototyped via aerosol jet printing. The batch reproducible aerosol jet printed microcoils have a diameter of 1800 μ m, trace width and trace spacing of 112.5 μ m, 12 μ m thickness, and inductance values of approximately 15.5 nH. Modelling results indicate that the coils have a combined depolarization–hyperpolarization region that spans 1.5 mm and produce a more restrictive spread of activation when compared with conventional CI. [ABSTRACT FROM AUTHOR]

Time synchronization among sensor devices connected through non-deterministic media is a fundamental requirement for sensor fusion and other distributed tasks that need a common time reference. In many of the time synchronization methods existing in literature, the estimation of the relation between pairs of clocks is a core concept; moreover, in applications that do not have general connectivity among its devices but a simple pairwise topology, such as embedded systems, mobile robots or home automation, two-clock synchronization is actually the basic form of the time estimation problem. In these kinds of applications, especially for critical ones, not only the quality of the estimation of the relation between two clocks is important, but also the bounds the methods provide for the estimated values, and their computational effort (since many are small systems). In this paper, we characterize, with a thorough parameterization, the possible scenarios where two-clock synchronization is to be solved, and then conduct a rigorous statistical study of both scenarios and methods. The study is based on exhaustive simulations run in a super-computer. Our aim is to provide a sound basis to select the best clock synchronization algorithm depending on the application requirements and characteristics, and also to deduce which ones of these characteristics are most relevant, in general, when solving the problem. For our comparisons we have considered several representative methods for clock synchronization according to a novel taxonomy that we also propose in the paper, and in particular, a few geometrical ones that have special desirable characteristics for the two-clock problem. We illustrate the method selection procedure with practical use-cases of sensory systems where two-clock synchronization is essential. [ABSTRACT FROM AUTHOR]

A growing variety of microelectronic devices and magnetic field sensors as well as a trend of miniaturization demands the development of low-dimensional magnetic materials and nanostructures. Among them, soft magnetic thin films of Finemet alloys are appropriate materials for sensor and actuator devices. Therefore, one of the important directions of the research is the optimization of thin film magnetic properties. In this study, the structural transformations of the Fe73.5Nb3Cu1Si13.5B9 and Fe72.5Nb1.5Mo2Cu1.1Si14.2B8.7 films of 100, 150 and 200 nm thicknesses were comparatively analyzed together with their magnetic properties and magnetic anisotropy. The thin films were prepared using the ion-plasma sputtering technique. The crystallization process was studied by certified X-ray diffraction (XRD) methods. The kinetics of crystallization was observed due to the temperature X-ray diffraction (TDX) analysis. Magnetic properties of the films were studied by the magneto-optical Kerr microscopy. Based on the TDX data the delay of the onset crystallization of the films with its thickness decreasing was shown. Furthermore, the onset crystallization of the 150 and 200 nm films began at the temperature of about 400–420 °C showing rapid grain growth up to the size of 16–20 nm. The best magnetic properties of the films were formed after crystallization after the heat treatment at 350–400 °C when the stress relaxation took place. [ABSTRACT FROM AUTHOR]

In this study, we successfully prepared a highly sensitive hydrogen peroxide sensor by directly growing heterostructure of cobalt oxide-sulfide nanosheets on three-dimensional foam. As a self-supporting sensor, it exhibited good activity and excellent stability for hydrogen peroxide detection with a sensitivity of 0.059 mA μM−1 cm−2, wide detection range of 2 to 954 μM, and low detection limit of 0.890 μM. In addition, such sensor also displayed outstanding selectivity and good current response retention of around 87.1% after long-term operation of 1500 s. The achieved results may be due to the synergistic effects generated by the formation of metallic oxide-sulfide heterostructure and unique hierarchical 3D structure, which improved electroactive surface area, electron transfer, and electrolyte/ion diffusion, thereby resulting in the enhancement of catalytic performance. Our research may introduce a promising option for fabricating highly catalytic electrocatalyst towards hydrogen peroxide detection in analytical applications. Unlabelled Image • A novel sensor of CoO-CoS sheet-like heterostructures on NF was facilely prepared. • The sensor detects H 2 O 2 with good sensitivity and low LOD of 0.89 μM. • The sensor detects H 2 O 2 with wide linear detection range of 2 to 954 μM. • The sensor exhibited good durability, selectivity as well as excellent stability. [ABSTRACT FROM AUTHOR]

Industrial monitoring and process control, power plants, aerospace industry, military equipment manufacturing, oil and gas industries are examples of businesses in need for high‐temperature and harsh‐environment electronic components and systems. In particular, resonators and filters that operate beyond the 125°C military range upper limit, normally dictated by silicon‐based semiconductor devices, are required in applications which demand frequency control, clocking and sensors. In this Letter, temperature compensated surface acoustic wave orientations appropriate for the fabrication of resonators and filters >125°C have been identified through numerical calculations and experimentally confirmed on a commercially available langasite wafer, a piezoelectric crystal which operates at high temperatures. Resonator filters have been designed, fabricated and tested along two orientations, confirming the zero temperature sensitivities at 150 and 300°C. These devices are of great interest for modern harsh environment frequency control, timing and sensor applications. [ABSTRACT FROM AUTHOR]

This work presents some accurate guidelines for the design of rectifier circuits in radiofrequency (RF) energy harvesting. New light is shed on the design process, paying special attention to the nonlinearity of the circuits and the modeling of the parasitic elements. Two different configurations are tested: a Cockcroft–Walton multiplier and a half-wave rectifier. Several combinations of diodes, capacitors, inductors and loads were studied. Furthermore, the parasitics that are part of the circuits were modeled. Thus, the most harmful parasitics were identified and studied in depth in order to improve the conversion efficiency and enhance the performance of self-sustaining sensing systems. The experimental results show that the parasitics associated with the diode package and the via holes in the PCB (Printed Circuit Board) can leave the circuits inoperative. As an example, the rectifier efficiency is below 5% without considering the influence of the parasitics. On the other hand, it increases to over 30% in both circuits after considering them, twice the value of typical passive rectifiers. [ABSTRACT FROM AUTHOR]