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The use of hydrogen as fuel presents many safety challenges due to its flammability and explosive nature, combined with its lack of color, taste, and odor. The purpose of this paper is to present an electrochemical sensor that can achieve rapid and accurate detection of hydrogen leakage. This paper presents both the component elements of the sensor, like sensing material, sensing element, and signal conditioning, as well as the electronic protection and signaling module of the critical concentrations of H2. The sensing material consists of a catalyst type Vulcan XC72 40% Pt, from FuelCellStore, (Bryan, TX, USA). The sensing element is based on a membrane electrode assembly (MEA) system that includes a cathode electrode, an ion-conducting membrane type Nafion 117, from FuelCellStore, (Bryan, TX, USA). and an anode electrode mounted in a coin cell type CR2016, from Xiamen Tob New Energy Technology Co., Ltd, (Xiamen City, Fujian Province, China). The electronic block for electrical signal conditioning, which is delivered by the sensing element, uses an INA111, from Burr-Brown by Texas Instruments Corporation, (Dallas, TX, USA). instrumentation operational amplifier. The main characteristics of the electrochemical sensor for hydrogen leakage detection are operation at room temperature so it does not require a heater, maximum amperometric response time of 1 s, fast recovery time of maximum 1 s, and extended range of hydrogen concentrations detection in a range of up to 20%. [ABSTRACT FROM AUTHOR]

Background. The article is devoted to the development of constructive and technological methods for ensuring the temporal and parametric stability of films and film structures formed on metal–film sensors of physical quantities. The relevance of the presented materials lies in the fact that the stability of sensors depends to a greater extent on the stability of resistive films and film structures. The purpose of the article is to develop reproducible designs and technologies that ensure the formation of time-stable sensor elements and structures. Materials and methods. The article describes in sufficient detail the proposed designs of polyfilm strain-resistant structures of various configurations. Mathematical models of multilayer film structures are considered and analyzed, the nominal values of strain gages are determined, and methodformation are determined. In particular, an increase in the accuracy and consistency of the electrophysical characteristics of the sensing elements and measuring modules was achieved by 30–40 % compared with well-known Russian sensors.s for minimizing the temperature coefficients of resistive structures are determined. Results and conclusions. As a result of the research conducted in the field of developing methods for regulating and maintaining the temporal and parametric stability of sensor characteristics, the designs of polyfilm structures and methods of their

Background. The paper investigates the sensing element of a capacitive pressure sensor based on a silicon corrugated membrane. Materials and methods. Using finite element modeling, the parameters of the corrugation were determined, which make it possible to double the sensitivity compared to a flat membrane having similar overall dimensions. Results and conclusions. It is shown that the presence of an edge corrugation with a rectangular profile makes it possible to increase the sensitivity of the membrane.

Introduction. At present, acceleration sensors are in demand in various areas, from consumer electronics to space technology. Microaccelerometers exhibit the advantages of compact dimensions, light weight, and ease of integration with other components. The most common accelerometers are based on microelectromechanical systems. However, due to the fragility of elastic suspensions, these devices are characterized by low impact resistance, which impedes their application in highly dynamic objects with accelerations of up to 50 000 g. The authors propose to use microaccelerometers based on surface acoustic waves, which are solid-state monolithic structures capable of withstanding high shock loads. Previous work has proposed the concept of concentric electrodes, which are more energy efficient compared to linear designs. However, concentric elements are difficult to connect to the electrical circuit, due to the impossibility of connecting the busbars directly. Therefore, the authors describe and simulate five alternative methods for connecting the sensing element of such devices.Aim. To select an optimal method for connecting the sensing element of microaccelerometers from the standpoint of maintaining the integrity of the electrodes and ensuring minimal influence on the propagation of surface acoustic waves.Materials and methods. Finite element simulation in the COMSOL Multiphysics software.Results. Five connection methods, including point-to-point wiring, removing the electrode sector, filling holes in the electrodes and substrate with metal, pulling wires through holes in the substrate and bringing out contact bars along the side face, were proposed and analyzed. Computer simulation was carried out. Graphs of the amplitude-frequency characteristic are presented.Conclusion. Among the considered methods for connecting the sensing element, the most appropriate seems to be method No. 3, which implies holes in the electrodes and contacts on the bottom side of the substrate. Here, the graph of the amplitude-frequency characteristic practically coincides with that of the sensor without connections (reference). Future work will focus on creating a prototype and its experimental testing.

This study proposes a dual-functional terahertz device based on the Dirac semimetal, serving as both a sensing element and a band-pass filter. The device's operating mode can switch between these two functions by utilizing the phase transition property of vanadium dioxide (VO2). When VO2 is in the insulating state, the device functions as a sensing element. The simulation results demonstrate an impressive refractive index sensitivity of 374.40 GHz/RIU (Refractive Index Unit). When VO2 is in the metallic state, the device functions as a band-pass filter, exhibiting a center frequency of 2.01 THz and a 3 dB fractional bandwidth of 0.91 THz. The integration of these dual functionalities within a single terahertz device enhances its utility in both sensing and filtering applications. [ABSTRACT FROM AUTHOR]

Background. Vibration measurement is one of the most popular and cost-effective methods of diagnosing the overall condition of equipment and is of undeniable importance in modern technology. Thanks to this process, manufacturers and consumers can be sure of the reliability and quality of technical systems, as well as prevent possible breakdowns and failures. And the wide scope of vibration measurements in various fields confirms their versatility and importance in modern technical progress. The purpose of measuring the effects of critical temperatures on a temperature transducer is to determine how a change in critical temperature can affect the accuracy and reliability of the transducer. This will improve the quality of temperature measurement, eliminate inaccuracies and errors in equipment performance, and increase the efficiency of the equipment in various operating conditions. Materials and methods. The research method in this paper is a simulation model of the sensor, which is used to test for vibration and exposure to critical temperatures. Ansys and SolidWorks Simulation software are used to create the model to avoid costly and time-consuming test cycles. Results. As a result of the simulation modeling, the epuples of mechanical stress distribution under sinusoidal vibration and the epuples of temperature distribution under critical temperatures were constructed.

Introduction. Modern mobile control objects require the use of highly sensitive transducers of motion parameters, e.g., acceleration, with a wide measurement range. Increased sensitivity to measured parameters can be achieved by using precision optics, e.g., based on the tunneling effect. However, operating ranges of induced movements are less than a micrometer, which creates difficulties in positioning the sensing element. In order to improve manufacturability, to extend the measurement range and to reduce errors of acceleration transducers with optical tunneling, compensation circuits with a piezoelectric actuator as an active sensor can be used.Aim. To extend the measurement range of microelectromechanical acceleration transducers through the use of an integrated approach, including the introduction of a compensation circuit for sensor movements based on the inverse piezoelectric effect and detection of these movements by optical means.Materials and methods. An approach to compensating sensor movements is proposed. This approach consists in using a bimorph piezoelectric plate as an inertial element. The use of optical reading of sensor sub-micrometer displacements is considered.Results. A block scheme and a functional scheme of a compensator micro-opto-electromechanical acceleration transducer with a bimorph piezoelectric sensing element are developed. Deformations in the sensing element under the influence of accelerations (up to 100 m/s2) and compensation voltages, whose amplitude does not exceed several volts, are investigated to ensure the possibility of using the optical tunneling effect in the proposed transducer.Conclusion. A mathematical model of the transducer was developed and studied. A 2.5-fold increase in the measurement range was achieved. It was shown that the introduction of compensation feedback does not decrease the permissible frequency range of measured accelerations.

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Ensuring the reliability of the functioning of MEMS devices is the most important task facing developers. Due to the variety of designs and materials used in MEMS devices, various failure mechanisms can occur. Most of these devices contain moving parts of the structure. The fatigue properties of the structural materials used and their aging under prolonged repetitive cyclic loading can lead to failure, which directly affects the reliability of the device. In this paper the fatigue properties and reliability of the sensitive element (SE) of a micromechanical accelerometer (MMA) sandwich structure of a capacitive type made of silicon under the conditions of the mechanism of fatigue failure of the material are analyzed. The number of cycles of periodic exposure for the occurrence of a failure and the failure rate of SEs are calculated. The crystallographic orientation of the surface plane of silicon—the SE material—is considered. The simulation results show that the fatigue life of SE of an MMA made of silicon can be sufficiently strong for general purpose applications. [ABSTRACT FROM AUTHOR]

A photocurable resin/carbon nanotube (CNT) nanocomposite was fabricated from aligned CNTs in an acrylic matrix. The conductivity of the nanocomposite increased rapidly and then stabilized when the CNT content was increased up to and beyond the percolation threshold. Various structures were created using a digital light processing (DLP) 3D printer. Various polymeric dispersants (SMA-amide) were designed and synthesized to improve the CNT dispersion and prevent aggregation. The benzene rings and lone electron pairs on the dispersant interacted with aromatic groups on the CNTs, causing the former to wrap around the latter. This created steric hindrance, thereby stabilizing and dispersing the CNTs in the solvent. CNT/polymer nanocomposites were created by combining the dispersant, CNTs, and a photocurable resin. The CNT content of the nanocomposite and the 3D printing parameters were tuned to optimize the conductivity and printing quality. A touch-based human interface device (HID) that utilizes the intrinsic conductivity of the nanocomposite and reliably detects touch signals was fabricated, enabling the free design of sensors of various styles and shapes using a low-cost 3D printer. The production of sensors without complex circuitry was achieved, enabling novel innovations. [ABSTRACT FROM AUTHOR]

Among piezo composites, 0–3 type ceramic/polymer-based composites have balanced properties and flexible manufacturing processes, allowing them to tackle challenges in wearable electronics and sensing technology. However, due to a misfit between the dielectric coefficients of the ceramic particles and polymer matrix, poling 0–3 composites is difficult. Therefore, in this study, we develop a novel poling method that combines the merits of normal corona poling and oil-based poling methods to activate a lead zirconium titanate (PZT)/Polyethylene glycol diacrylate (PEGDA) composite. The influence of various parameters (voltage, temperature, poling duration, and time of ageing) on the piezoelectric and dielectric properties of the PZT/polymer composite were evaluated. For the 0–3 PZT/PEGDA composites (67 wt%), the optimal poling parameters were found to be 60 min poling duration, 25 °C, and 24 kV. The d 33 (32 pC/N) obtained by the proposed poling method is about 3 times that obtained by the normal corona poling method (11 pC/N). This modified poling method was shown to be more effective than the conventional method for a range of filler contents (50 wt%, 67 wt%, and 75 wt%). It was also found that the d 33 value of the PZT/PEGDA composite increased over time and was attributed to the increase of the composite dielectric constant after poling. Finally, sensing elements were assembled from the poled samples and evaluated, which shows the potential for detecting tiny signals in sensing and soft robotics. [ABSTRACT FROM AUTHOR]

Background. At present, the efficiency of development and operation of modern automated systems of control and management of various technological processes is largely determined by the technical and economic characteristics of the primary transducers of information (sensors) among which the important place belongs to displacement sensors. The mathematical model of mutual inductive linear displacement sensors underlying the calculation algorithm developed on the basis of the solution of the boundary electrodynamic problem of interaction of a homogeneous alternating field with an electromagnetic rod is considered. Materials and methods. The systems of Poisson's and Laplace's equations with respect to the vector potential were used in this work. Results. As a result of this research, a mathematical model was proposed, which was used in the development of the TDS designed to measure the movements of the solar panels of a satellite vehicle in open space conditions.

Micromechanical accelerometers (MMAs) are widely used in industry and in robotechnics, as they are characterized by low power consumption, small size and weight, and low cost in serial production. Therefore, the development and research of MMAs is an urgent task. In this study, when modeling the sensitive element (SE) of MMAs, a software system of finite element analysis is used, which allows for static and modal analysis. The results of the preliminary calculations of the MMA scale factor, which can be collected based on the developed SE and sigma-delta transducer, are presented. The technological process of manufacturing the SE of MMAs using anisotropic liquid chemical etching of silicon to obtain different profiles of the corresponding crystallographic planes is described. The results of studying the effect of technological errors on the geometrical dimensions of the SE are presented: the dependence of the value of the lateral underetching of silicon on the accuracy of the angular alignment of the mask with the crystallographic axis of the plate (100) is revealed. The simulation performed confirms the operability of the design, the calculations show a change in the scale factor in the temperature range from –60 to +125°C, nominal capacitance, and capacitance with a change in linear acceleration in the range of ±60 g. In manufacturing SEs based on the the studies performed, it is possible to obtain a lateral underetching of up to 5 μm at an anisotropic liquid chemical etching depth of 250 μm for KDB-0.01 wafers with an orientation tolerance of ±30 arc minutes or with a misorientation of the same value allowed during exposure. [ABSTRACT FROM AUTHOR]

The aim of this work is to propose two different and integrated sensors for the structural health monitoring of concrete beams. In particular, a diffused sensing element and a split ring resonator network are presented. The first sensor is able to detect the variations in the dielectric properties of the concrete along the whole beam length, for a diffuse monitoring both during the important concrete curing phase and also for the entire life cycle of the concrete beams. The resonators instead work punctually, in their surroundings, allowing an accurate evaluation of the permittivity both during the drying phase and after. This allows the continuous monitoring of any presence of water both inside the concrete beam and at points that can be critical, in the case of beams in dams, bridges or in any case subject to a strong presence of water which could lead to deterioration, or worse, cause serious accidents. Moreover, the punctual sensors are able to detect the presence of cracks in the structure and to localize them. [ABSTRACT FROM AUTHOR]

Measurements of magnetic field parameters are the basis of all magnetic measurements. Most methods of measuring magnetic field parameters are based on force (energy) interaction of magnetic field with macro- or microscopic currents and electromagnetic induction. The paper considers the possibility of constructing a magnetic field strength gradient meter based on the absolute helical instability of electron-hole plasma of a semiconductor sample. The functional scheme of the gradiometer and the results of experimental and theoretical studies of the sensitive element of the gradiometer are presented.

A tri-axial stress sensor was designed to measure contact stresses in the tire–pavement contact patch. The shape and size of the sensor surface were designed considering both the asphalt pavement texture and the tire pattern. The top-down cracking mechanism was also taken into account, and the sensor was placed at the vertical crack depth. Temperature drifts and zero drifts were compensated for. The sensor had high structural strength and met the sensing requirements of specialized heavy vehicles. In a preliminary study, three sensors were fabricated and calibrated in three directions. Simulated measurements were performed using a tire–pavement surface contact test bench. Signals from the L-shaped sensor region were obtained for the upper, middle, and lower parts of the tire, and preliminary stress distributions were determined at different positions on the contact surface. This study has laid a foundation for the design and construction of a more precise test system in the future. [ABSTRACT FROM AUTHOR]

Modern and perspective tasks of robotics with control from artificial intelligence systems require the use of small-sized measuring devices. In this case, the intensively developed quantum sensors and quantum computers have a bright prospect. Their main advantage is the ability to successfully process the data of random processes with decomposition of complex functions into simple multipliers, as well as their small size and the ability to transmit data over long distances without wires. Data transmitted over quantum communication lines cannot be copied or intercepted, which is very useful for remote control of complex technical systems. Based on the results of the analysis of probabilistic noisy data quantum computer is able to quickly develop an assessment of the technical condition of the complex system. At the same time, there is no need to go through all the possible solutions to the evaluation problem with a huge amount of input data, some of which can sometimes be undefined. The main problem in the research of quantum processes is that researchers study the processes occurring in materials, but they do not indicate the ways in which quantum sensors and quantum computers are used in practical applications. This article explains how to form a measuring transformer that will be compatible with a quantum computer. The main objective of the study was to bring the results of basic research in the field of quantum computing closer to their application in applied tasks. It is shown how quantum processes can be shifted to the field of technical measurements of physical quantities used in complex systems. In the process of obtaining the results of the study, the hypothetical deductive method and the method of ascent from the abstract to the concrete within the framework of a systematic approach to the development of elements of technical systems were used. The result is a description of the processes of designing of tension sensing element made of modified diamond. The main findings of the study include the fact that quantum sensors implemented in the form of a modified diamond crystal are well described by the theory of measuring transducers with frequency output and can be used to get data about the state of an object.

The article provides a comparative analysis of multi-element sensors of an electric field of a flat shape differing in various configurations of sensitive elements, each of which is determined by its design parameters. For this, a generalized mathematical model of the sensor is compiled taking into account its design parameters which affect the error from field inhomogeneity and the spatial range of measurement. Using a generalized mathematical model, graphs of the sensor error are constructed depending on the spatial measurement range and various design parameters of its sensitive elements. The change in design parameters allowed us to model sensitive elements in the form of quadrants and truncated quadrants of a circle. According to the error graphs, it is established that sensitive elements made in the form of quadrants of a circle provide the sensor with a lower error and a larger spatial range of measurement, therefore their use is more appropriate. The studies performed allowed us to obtain the following technical results. Sensors with sensitive elements in the form of a quadrant of a circle have a minimum of an error and a maximum of a spatial range of measurement at design parameters: b = 0 and b0 = 0,2; b = 0 and b0 = 0.4, for which, with a maximum spatial range of measurement equal to unity (a = 1), the errors are respectively minus 3 % and minus 10 %.

Continuous measurement of temperature profiles on the human body surface provides handy information for the diagnosis and as a beneficial guide to take appropriate action. A textile based Resistance Temperature Detector (RTD) has been reported recently, which could be exploited to monitor the temperature of human body over extended period of time. For the purpose of calibrating these textile based sensor, a tailor-made test rig has been developed. The working principle of this sensing fabric is the same as the RTD i.e. change in resistance because of change in temperature. Validation of experimental results by modelling was one of the prime objectives of this study. This paper reports the steady state mathematical model of the test rig components, by the application of fundamental heat transfer principles. It was concluded that the temperature varies linearly across the thickness of textile based temperature sensor in a rig setting while the temperature of the sensing element of textile based temperature sensor could be approximated by knowing its exact position within the fibrous structure. This input would be helpful for the calibration purpose of the sensor samples in an improved manner and to circumvent the individual testing and repetition of experiments on a test rig. [ABSTRACT FROM AUTHOR]

Inorganic piezoelectric ceramic composite is the potential sensing element for long-term structural health monitoring due to its excellent durability and compatibility. In this study, a Ceramicrete-based piezoelectric composite is proposed preliminarily, in which the magnesium potassium phosphate cement is used as the matrix and the lead zirconate titanate particle is utilized as the functional phase. Piezoelectric properties test and microstructure analysis are performed to evaluate the testing samples. Results show that the piezoelectric performance of the composite increase with the increase of piezoelectric ceramic particle size. The value of the piezoelectric strain factor (d 33) can reach 83.8 pC/N, while the corresponding piezoelectric voltage factor (g 33) is 50.1 × 10-3 V•m/N at the 50th day after polarization. Microstructure analysis illustrates that the interfacial transition zone (ITZ) between the matrix and the particles is dense. Moreover, the influence of aging on the composite is attributed to the continuous hydration after polarization. It indicates that the composites have a higher piezoelectric performance, which can be regarded as a promising sensing element material. [ABSTRACT FROM AUTHOR]

In aviation measurement of static and total pressure is widely used to determine the flight conditions. Results of pressure measurements are used to monitor flight attitude, equivalent speed, Mach number, vertical velocity etc. The algorithm for data acquisition and processing for developed pressure measurement system is presented in this paper.

Sensing elements in Stress-In-Motion (SIM) system were designed to measure vertical and tangential tire-pavement contact forces under uniform loading conditions. However, in reality, the contact forces are not uniformly distributed. Compared with tangential shear force, non-uniform vertical contact force causes a bending moment which may take significant errors to tri-axial contact stress measurements. In the research, three tire thread-sensing element contact conditions (uniform, non-uniform and point load) were applied and influences of the non-uniformity on vertical and tangential stress signals were determined by finite element method. It was found that significant errors may occur as a result of the contact force non-uniformity. The error of the vertical contact force measurement was up to 65% (non-uniform load). In extreme situation with point load, the error would be greater. The errors caused by vertical contact force non-uniformity to the tangential contact stress measuring signals were 15% (non-uniform force) and 60% (point load). So designing of the SIM sensing element and decoupling method between measuring signals should be carefully reconsidered. [ABSTRACT FROM AUTHOR]

This study investigates the nitric oxide (NO) gas sensing performance of room temperature sputtered nanocrystalline WO 3 thin films deposited on Si substrate in a single step without heat treatment. The prepared WO 3 /Si sample properties have been systematically characterized for crystallographic, surface morphology, elemental, and chemical bonding analysis by XRD, FE-SEM, EDS, and XPS techniques, respectively. It has been observed that the thin film samples have a nanocrystalline structure with a granular-like porous morphology, and the presence of oxygen or metal vacancies/defects contributes to improving the sensing response of a target gas. The gas sensing performance of WO 3 thin film deposited over Si (WO 3 /Si) has been recorded at various crucial parameters such as different operating temperatures (200–325 °C), gas concentrations (3–100 ppm), and target gases (H 2 S, CO, NH 3 , NO, and NO 2). The maximum sensor response for 100 ppm concentration of NO gas was achieved at an operating temperature of 250 °C with a response time of ∼172 s and a recovery time of ∼86 s. At the optimal operating temperature of 250 °C, the lowest NO gas concentration was measured as low as 3 ppm. The calculated theoretical detection limit for NO gas at this concentration was determined to be 167 ppb. Further, the sample shows long-term stability over a period of 33 days and preserves the same value of sensor response. The selectivity performance tested for various gases clearly indicates that our sample is highly selective towards NO gas. This improved sensing performance can be attributed to the granular-like porous structure and excessive oxygen vacancies on the sample surface. The underlying sensing mechanism for superior response to NO gas has also been discussed. These results demonstrate the potential application of nanocrystalline WO 3 /Si thin film prepared at room temperature for the development of high-performance and cost-effective single-material-based metal oxide gas sensors. [Display omitted] • WO 3 /Si thin films were deposited at room temperature by reactive magnetron sputtering for highly responsive and selective NO gas sensing. • Maximum sensor response (SR) ∼ 22.7 with fast response/recovery time (172s/86s) for 100 ppm NO gas was achieved at relatively lower operating temperature of 250 °C. • WO 3 /Si thin films exhibit a good sensor response for lowest measurable concentration of 3 ppm NO gas with a calculated detection limit of 167 ppb. • Also, the WO 3 /Si thin films are highly stable and selective for NO gas compared to other target gases such as H 2 S, CO, NH 3 , and NO 2. • Granular-like porosity and excessive oxygen vacancies present in the WO 3 /Si thin films improved the sensing performance. [ABSTRACT FROM AUTHOR]

In this paper, a new approach to effective detection of THz radiation is proposed using a configuration of thin metal and thin dielectric films; to this end, the design and performance of an effective composite absorber of THz radiation that can be used as the sensing element of a thermal detector are presented. A composite absorber consists of a set of two double-layered elements of a thin metal layer located on a dielectric material and is designed through a fine-tuning process. The results indicate that the proposed low-cost absorber can be widely tuned based on the metal layer sheet resistance and the thickness of various dielectric media. The development of a proper non-linear system of equations has as input the desired frequency and bandwidth of the absorbed THz radiation and output the required metrics of dielectric refractive index, the dielectric thickness and the metal's sheet resistance that comprise the absorber. [ABSTRACT FROM AUTHOR]

Compatibility, a critical issue between sensing material and host structure, significantly influences the detecting performance (e.g., sensitive, signal-to-noise ratio) of the embedded sensor. To address this issue in concrete-based infrastructural health monitoring, cement-based piezoelectric composites (piezoelectric ceramic particles as a function phase and cementitious materials as a matrix) have attracted continuous attention in the past two decades, dramatically exhibiting superior durability, sensitivity, and compatibility. This review paper performs a synthetical overview of recent advances in theoretical analysis, characterization and simulation, materials selection, the fabrication process, and application of the cement-based piezoelectric composites. The critical issues of each part are also presented. The influencing factors of the materials and fabrication process on the final performance of composites are further discussed. Meanwhile, the application of the composite as a sensing element for various monitoring techniques is summarized. Further study on the experiment and simulation, materials, fabrication technique, and application are also pointed out purposefully.

This work shows the possibility of using arrays of ZnO nanorods grown on a glass substrate as a sensitive element for measuring air flow velocity. Since oxide semiconductors have a temperature dependence of resistance, a theoretical and experimental assessment was made of the influence of air velocity on the increase in resistance of a sensitive element. It has been theoretically shown that when air is blown through, the temperature of the free end of the ZnO nanorod can decrease by several degrees. An experimental evaluation showed that when gas is blown at a speed of 12.5 cm/s, the resistance of the sensing element increases by about 20%, which is equivalent to a temperature increase of about 4 degrees. In addition, it was found that the dependence of the increase in the resistance of the sensitive element when exposed to an air flow from 0 to 12.5 cm / s is close to linear.

The silicon micromechanical gyroscope, which will be introduced in this paper, represents a novel MEMS gyroscope concept. It is used for the damping of a single-channel control system of rotating aircraft. It differs from common MEMS gyroscopes in that does not have a drive structure, itself, and only has a sense structure. It is installed on a rotating aircraft, and utilizes the aircraft spin to make its sensing element obtain angular momentum. When the aircraft is subjected to an angular rotation, a periodic Coriolis force is induced in the direction orthogonal to both the angular momentum and the angular velocity input axis. This novel MEMS gyroscope can thus sense angular velocity inputs. The output sensing signal is exactly an amplitude-modulation signal. Its envelope is proportional to the input angular velocity, and the carrier frequency corresponds to the spin frequency of the rotating aircraft, so the MEMS gyroscope can not only sense the transverse angular rotation of an aircraft, but also automatically change the carrier frequency over the change of spin frequency, making it very suitable for the damping of a single-channel control system of a rotating aircraft. In this paper, the motion equation of the MEMS gyroscope has been derived. Then, an analysis has been carried to solve the motion equation and dynamic parameters. Finally, an experimental validation has been done based on a precision three axis rate table. The correlation coefficients between the tested data and the theoretical values are 0.9969, 0.9872 and 0.9842, respectively. These results demonstrate that both the design and sensing mechanism are correct.

Recently, many researchers have studied to overcome some disadvantages of conventional sensing mechanisms. And the flexoelectric effect draw great attention as key to enhance the sensor performance especially in micro/nano scale. However, the relatively low flexoelectric effect in macro scale becomes a difficulty to commercialization. In this paper, in order to enhance the performance of sensor using the flexoelectric effect, the sensing element of duplex frustum pyramid is suggested as an alternative to the sensing element of single frustum pyramid. The flexoelectric characteristics for the duplex frustum pyramid, which is made of barium strontium titanate (Ba0.65Sr0.35TiO3 - BST) ceramic, are investigated numerically. If the height, top surface, edge angle and flexoelectric coefficient of the single and duplex frustum pyramids are identical (H = 2 mm, θ = 45°, μ11 = 100 μC/m and a = 1 mm), the total volume of the duplex frustum pyramid is about 60 % of the case of the single frustum one. Moreover, the charge output for the duplex frustum pyramid becomes nearly double of the sensing element of single frustum pyramid. Also, most of charge output develops in the neighborhood of the top and bottom surfaces it is much preferable to use the sensing element of duplex frustum pyramid rather than use the sensing element of single frustum pyramid as long as it is manufacturable. [ABSTRACT FROM AUTHOR]

This article considered method to measure low-frequency angular oscillations of rotors of electric machines and solved the problem of assess shear deformations of rotating shafts in transient conditions. Method of calculating torsional torques is considered by the example of electric generator shaft of diesel generator unit. This method allows taking into account the angular deformations of the rotating shafts, and reducing vibration overloads, and increasing in both resource and reliability. [ABSTRACT FROM AUTHOR]

Abstract A new improved test system was developed based on the non-contact inductance method, which can be used to characterize the piezomagnetic properties of Fe-based amorphous alloy ribbons properly. The studies show that when the test frequency is 1 kHz, the voltage is 0.3 V and the compressive stress σ ≤ 0.1 MPa, the amorphous magnetic material of Fe 73.5 Cu 1 Nb 3 Si 13.5 B 9 has excellent piezomagnetic properties, and its ribbons of different specifications exhibit perfect stability and repeatability after repeated experiments. The ribbons are extremely sensitive to tiny stress, and they show a rapidly rising trend of the inductance once the initial pressure is applied on the ribbons. Moreover, the further amplifying experiment indicates that the sensitivity range is 0∼1.5 kPa. In addition, the size of Fe 73.5 Cu 1 Nb 3 Si 13.5 B 9 ribbons influence significantly the piezomagnetic property, and the initial inductance and its corresponding S I-Max value of the ribbons increase substantially along with the sample size increasing; with the same width, the piezomagnetic property is superior to others while the thickness is 33∼36 µm, and S I-Max is 19.8%. With the same thickness, the ribbons with a width of 20 mm show an excellent piezomagnetic property and the S I-Max has reached 22.02%. [ABSTRACT FROM AUTHOR]

The influence of birefringence fibre (BF) loop mirror (Bi‐FLM) length on the light intensity sensitivity to strain was analysed theoretically and investigated experimentally. The same type of BF but the different length was chosen as the sensing element to be glued to the test object. The relationship between the light intensity and strain was obtained for the Bi‐FLM with different BF length. Afterwards, the light intensity signals were converted into voltage signals. The influence of BF length on the average voltage sensitivity to strain was investigated experimentally. The experimental results indicate that the Bi‐FLM with a long BF has a high average voltage sensitivity to strain but a small strain measurement range, while the Bi‐FLM with a short BF has a low average voltage sensitivity to strain but a large strain measurement range. From the experiments carried out, it was seen that the average voltage sensitivity to strain can be improved by increasing the BF length. This method does not increase the system complexity. [ABSTRACT FROM AUTHOR]

Abstracts: This review presents the results of the development of gas chemical nanosensors with sensitive elements based on gallium, cadmium, cerium, cobalt, vanadium, silicon, manganese, niobium, zirconium, aluminum, bismuth, lanthanum, magnesium, palladium, antimony, sodium, samarium, platinum, barium, lithium, and potassium. The developed devices are systematized in accordance with the features of construction of their sensing elements. The analytical capabilities of these devices are considered, and the observable regularities are noted. In particular, the potential of these nanosensors for use in the identification of a large number of inorganic and organic chemical compounds is demonstrated. The effect of the morphology and composition of the coating and temperature of the sensing element on the sensitivity and selectivity of measurements and the response and recovery times is shown. [ABSTRACT FROM AUTHOR]

Methods and algorithms for control of the operation of a thermocatalytic gas sensor are examined. The use of the data of the methods and algorithms decreases measurement errors and increases the sensor’s service life. [ABSTRACT FROM AUTHOR]

The results of the development of gas chemical nanosensors with sensing elements based on molybdenum oxide, iron oxides, and chromium oxide are presented in the review. The developed devices are systematized in accordance with the features of the construction of their sensing elements; the groups of nanosensors based on molybdenum oxide, iron oxides, and chromium oxide are divided each into three subgroups. The analytical capabilities of these devices are considered and the observable regularities are noted. In particular, the potential of nanosensors in identifying a large number of inorganic and organic chemical compounds is demonstrated. The effect of the morphology and composition of the coating and temperature of the sensing element on the sensitivity and selectivity of the measurements and the response and recovery times is shown. [ABSTRACT FROM AUTHOR]

Metallic multilayer spin-valve nanostructures that comprise the exchange-coupled ferromagnet/ Ru/ferromagnet structure in the free layer have been synthesized by magnetron sputtering. For microobjects (meanders) formed from CoFe/Cu/CoFe/Ru/CoFe/FeMn/Ta spin valves with different thicknesses of ruthenium and copper layers, the dependences of the magnetoresistive sensitivity and low-field hysteresis loop shift on the meander strip width have been studied. Sensing elements characterized by high magnetoresistive sensitivity have been manufactured. [ABSTRACT FROM AUTHOR]

The results of the development of gas chemical nanosensors with sensing elements based on copper and nickel oxides are presented in the review. The developed devices are systematized in accordance with the construction features of their sensing elements. Both types of nanosensors are divided into three groups. The first group includes devices with sensing elements containing a coating of only copper oxide or nickel oxide. The second group combines devices with sensing elements containing a coating of a layer of copper oxide or nickel oxide with an outer layer of another material. The third group are nanosensors with sensing elements containing a coating in the form of a layer of a composite material based on copper oxide or nickel oxide. The performance characteristics of these groups of devices are considered. Some patterns in their behavior are discussed. In particular, the potential of nanosensors in the identification of a large number of inorganic and organic chemical compounds is demonstrated. The effect of the morphology, thickness, and composition of the coating and temperature of the sensing elements on the sensitivity and selectivity of measurements and the response and recovery times is shown. [ABSTRACT FROM AUTHOR]

The authors have recently developed a time‐domain reflectometry (TDR)‐based leak‐localisation system which, being based on an electromagnetic technique, overcomes the well‐known downsides (sensitivity to environmental noise, to pipe material and geometry etc.) of traditional, electro‐acoustic leak‐localisation techniques. Starting from the positive results obtained so far, in this work, the authors investigate the possibility of implementing an integrated TDR/ground penetrating radar (TDR/GPR) approach. The TDR would allow the preliminary leak localisation, while the GPR technique would be used to have a countercheck for possible false positives. Also, GPR would allow to assess the quantity of the leaked water (thus scheduling a priority order for repair) and to obtain a three‐dimensional view of the subsurface soil around the pipes, so as to assess their health status. In this work, the combined TDR/GPR approach is tested on a pipe section in the presence of two leaks. In addition to this, in this study, also a different configuration of the TDR sensing element (SE) is experimented. As described in what follows, this new SE configuration is expected to expedite considerably the implementation and the use of the TDR‐based leak detection system. [ABSTRACT FROM AUTHOR]

Early-stage disease detection by volatile organic compounds (VOCs) monitoring in breath is a rapidly emerging field of research. Development of corresponding sensors requires highly sensitive and selective sensing elements that can ideally be adjusted for specific target VOCs or biomarker footprints. Smart hydrogels are very interesting candidates for sensing elements, specifically in the biomedical context, as they exhibit a reversible swelling change in response to external stimuli. Moreover, they can easily be tailored for biocompatibility, selectivity and specificity to target analytes. Hence, they could be very promising for VOC detection. However, their applications are so far limited to liquid environments as the swelling response is based on the uptake and release of liquid. The performance in gaseous environments has not been investigated in depth so far. Here, we therefore present a first study of different synthetic acrylamide-based smart hydrogels for use in ambient air with varying relative humidity and investigate their potential for VOC detection with the test analytes acetone and isopropanol. We find that the studied hydrogels (i) maintain their swelling response even in low humidity and present a measurable weight change, (ii) exhibit a distinct response for acetone and isopropanol, and that (iii) PNIPAAm-based hydrogels show the largest response for both analytes and allow a discrimination between them. Conclusively, we demonstrate the feasibility of smart hydrogels as sensing elements for VOCs detection in gaseous environments. [Display omitted] • Comprehensive investigation of smart hydrogel swelling in gaseous environment for acrylamide- and NIPAAm-based materials. • Study of organic gas sorption (acetone and isopropanol) of smart hydrogels in varying relative humidity (0%–100%). • Poly(N -isopropylacrylamide) identified as most promising candidate for detection of and discrimination between tested VOCs. • Additional features observed and described for PAM and PAA hydrogels. [ABSTRACT FROM AUTHOR]

In this study, we propose a highly sensitive multichannel pH sensor that is based on an optical-fiber pulse width modulation (PWM) technique. According to the optical-fiber PWM method, the received sensing signal's pulse width changes when the optical-fiber pH sensing-element of the array comes into contact with pH buffer solutions. The proposed optical-fiber PWM pH-sensing system offers a linear sensing response over a wide range of pH values from 2 to 12, with a high pH-sensing ability. The sensitivity of the proposed pH sensor is 0.46 μs/pH, and the correlation coefficient R² is approximately 0.997. Additional advantages of the proposed optical-fiber PWM pH sensor include a short/fast response-time of about 8 s, good reproducibility properties with a relative standard deviation (RSD) of about 0.019, easy fabrication, low cost, small size, reusability of the optical-fiber sensing-element, and the capability of remote sensing. Finally, the performance of the proposed PWM pH sensor was compared with that of potentiometric, optical-fiber modal interferometer, and optical-fiber Fabry-Perot interferometer pH sensors with respect to dynamic range width, linearity as well as response and recovery times. We observed that the proposed sensing systems have better sensing abilities than the above-mentioned pH sensors. [ABSTRACT FROM AUTHOR]

Paper reports activation energy and humidity sensing studies of SnO 2 -doped ZnO nanomaterial prepared by solid-state reaction route. Prepared nanopowders were hydraulic-pressed to form pellets and annealed at temperatures of 400 °C to 700 °C. Pellet samples of SnO 2 -doped ZnO nanomaterials with 2, 6, 10, 15 and 16 wt% of SnO 2 in ZnO were prepared. XRD showed peaks of tetragonal cassiterite and hexagonal zincite. For the best sample of 15% SnO2-doped ZnO nanomaterials, the crystallite sizes were in the range of 27–124 nm evaluated from XRD. Average grain size for this sample as measured from SEM micrograph was 198 nm. SEM micrograph suggested agglomeration of smaller crystallites to form larger grains. Low activation energy value suggested that the sample could be used at room temperature. An increase of SnO 2 percentage in ZnO as well as the increase in annealing temperature both enhanced the sensitivity of the sample. Sensing element of 15 wt% SnO 2 -doped ZnO, annealed at 700 °C, showed the best results with sensitivity of 32.16 MΩ/%RH in the 15%–95% relative humidity range. Properties like low hysteresis, less effect of ageing and high reproducibility were exhibited by this sample. [ABSTRACT FROM AUTHOR]

The results of the development of gas chemical nanosensors with sensing elements based on titanium dioxide are presented in the review. The developed devices are systematized in accordance with the features of construction of their sensing elements. Four groups of nanosensors are specified: devices with sensing elements containing a coating of only titanium dioxide (Group 1), nanosensors with sensing elements containing a coating of a layer of titanium dioxide with an outer layer of another material (Group 2), devices with sensing elements containing a coating of a composite material based on titanium dioxide (Group 3), and nanosensors with sensing elements containing a coating of a layer of a composite material based on titanium dioxide with an outer layer of another material (Group 4). The analytical capabilities of the devices of these groups are assessed. Some patterns in their behavior are discussed. In particular, the potential of nanosensors in the identification of a large number of inorganic and organic chemical compounds is demonstrated. The effect of thickness, morphology, composition of the coating, and temperature of the sensing elements on the sensitivity and selectivity of measurements and the response and recovery times is shown. [ABSTRACT FROM AUTHOR]

In this paper, we propose a temperature/thermal sensor that contains a Rhodamine-B sensing membrane. We applied two different sensing methods, namely, fiber-optic pulse width modulation (PWM) and an interdigitated capacitor (IDC)-based temperature sensor to measure the temperature from 5 °C to 100 °C. To the best of our knowledge, the fiber-optic PWM-based temperature sensor is reported for the first time in this study. The proposed fiber-optic PWM temperature sensor has good sensing ability; its sensitivity is ~3.733 mV/°C. The designed temperature-sensing system offers stable sensing responses over a wide dynamic range, good reproducibility properties with a relative standard deviation (RSD) of ~0.021, and the capacity for a linear sensing response with a correlation coefficient of R2 ≈ 0.992 over a wide sensing range. In our study, we also developed an IDC temperature sensor that is based on the capacitance variation principle as the IDC sensing element is heated. We compared the performance of the proposed temperature-sensing systems with different fiber-optic temperature sensors (which are based on the fiber-optic wavelength shift method, the long grating fiber-optic Sagnac loop, and probe type fiber-optics) in terms of sensitivity, dynamic range, and linearity. We observed that the proposed sensing systems have better sensing performance than the above-mentioned sensing system. [ABSTRACT FROM AUTHOR]