Sensor Operation Research Articles

Eddy currents operation parameters optimization

With the development of non-destructive inspection techniques, more and more challenging situations have arisen and the correct choice of operating parameters can be decisive for a good detection sensitivity. Based on that, an algorithm was developed to obtain the best combination of an eddy current sensor operation parameters. The results obtained demonstrate the improvement in the cracks detection in welded parts after optimization.

ОСОБЛИВОСТІ АНІЗОТРОПНОГО БІПОЛЯРНОГО ТЕРМОЕЛЕМЕНТА

Modern information communication networks include monitoring subsystems. The operation of monitoring subsystems is based on the operation of various sensors. Among the sensors used in the monitoring subsystems, thermoelectric sensors occupy an insignificant share. In order for thermoelectric sensors to become more widespread, it is necessary to solve the problem of a small value of thermoelectric efficiency. It is proposed to solve this problem by switching to sensors based on anisotropic bipolar thermoelement. In the presented work, the influence of thermoelectric vortices with turbulent flow on the sensitivity of sensors based on anisotropic bipolar thermoelements was studied. The dependence of the value of the transverse thermal-EMF of this structure on the anisotropy coefficient K of the anisotropic bipolar thermoelectric material was determined. Corresponding singular points and limits of their existence are revealed. The dependence of the directions of rotation of vortices with a turbulent nature of the flow on the direction of approach to these points was established. The temperature sensitivity of the sensor based on an anisotropic bipolar thermoelement made of single crystals of cadmium antimonide with both unipolar and bipolar characteristics was evaluated. Research results show a significant increase in the temperature sensitivity of such sensors based on anisotropic bipolar thermoelements, which can be used as thermal sensors for monitoring individual elements of the information communication system. Such thermoelements will have an improved coefficient of temperature dependence of volt-watt sensitivity compared to anisotropic unipolar thermoelements. The conducted numerical calculations show the prospects of using anisotropic bipolar thermoelements as sensors for monitoring modern information and communication systems for collecting information, both about the system itself and the environment.

Wearable Loop Sensor for Bilateral Knee Flexion Monitoring.

We have previously reported wearable loop sensors that can accurately monitor knee flexion with unique merits over the state of the art. However, validation to date has been limited to single-leg configurations, discrete flexion angles, and in vitro (phantom-based) experiments. In this work, we take a major step forward to explore the bilateral monitoring of knee flexion angles, in a continuous manner, in vivo. The manuscript provides the theoretical framework of bilateral sensor operation and reports a detailed error analysis that has not been previously reported for wearable loop sensors. This includes the flatness of calibration curves that limits resolution at small angles (such as during walking) as well as the presence of motional electromotive force (EMF) noise at high angular velocities (such as during running). A novel fabrication method for flexible and mechanically robust loops is also introduced. Electromagnetic simulations and phantom-based experimental studies optimize the setup and evaluate feasibility. Proof-of-concept in vivo validation is then conducted for a human subject performing three activities (walking, brisk walking, and running), each lasting 30 s and repeated three times. The results demonstrate a promising root mean square error (RMSE) of less than 3° in most cases.

Development of Direct Electron Transfer-Type Extended Gate Field Effect Transistor Enzymatic Sensors for Metabolite Detection.

In this work, direct electron transfer (DET)-type extended gate field effect transistor (EGFET) enzymatic sensors were developed by employing DET-type or quasi-DET-type enzymes to detect glucose or lactate in both 100 mM potassium phosphate buffer and artificial sweat. The system employed either a DET-type glucose dehydrogenase or a quasi-DET-type lactate oxidase, the latter of which was a mutant enzyme with suppressed oxidase activity and modified with amine-reactive phenazine ethosulfate. These enzymes were immobilized on the extended gate electrodes. Changes in the measured transistor drain current (ID) resulting from changes to the working electrode junction potential (φ) were observed as glucose and lactate concentrations were varied. Calibration curves were generated for both absolute measured ID and ΔID (normalized to a blank solution containing no substrate) to account for variations in enzyme immobilization and conjugation to the mediator and variations in reference electrode potential. This work resulted in a limit of detection of 53.9 μM (based on ID) for glucose and 2.12 mM (based on ID) for lactate, respectively. The DET-type and Quasi-DET-type EGFET enzymatic sensor was then modeled using the case of the lactate sensor as an equivalent circuit to validate the principle of sensor operation being driven through OCP changes caused by the substrate-enzyme interaction. The model showed slight deviation from collected empirical data with 7.3% error for the slope and 8.6% error for the y-intercept.

Drowsy Driver Sleeping Device and Driver Alert System

Drowsiness is the main cause for major accidents which leads to the injuries, deaths and damages. To overcome this problem, we propose a system which uses various sensors. These sensors are used to detect the driver drowsy and monitor the health of the driver. The buzzer is used to alert the driver whenever the driver feels drowsy. Whenever the sensor values are not in the range of threshold value, the motor stops. In case of emergency, the GPS module determines the location and this information is sent through GSM to the particular person or in charge ward. All these sensor operations are controlled by Microcontroller. With the help of this system, the major road accidents canbe reduced by alerting the driver

Electrochemical Synthesis of Sound: Hearing the Electrochemical Double Layer.

Electrochemical double layers (EDLs) govern the operation of batteries, fuel cells, electrochemical sensors, and electrolyzers. However, their invisible nature makes their properties and function difficult to conceptualize, creating an impediment to the broader understanding of double-layer function required for future technologies in energy storage and chemical synthesis. To render the behavior of electrochemical interfaces more intuitive, we made the rearrangement of interfacial components audible by employing the EDL as a variable element in a relaxation oscillator circuit. Connecting the circuit to a speaker generated an audible output corresponding to the change in potential resulting from EDL rearrangement. Variations in the applied voltage, electrolyte concentration and identity, as well as in the electrode material, yielded audible frequency variations that provide an intuitive understanding of EDL behavior. We expect that hearing the trends in behavior will provide a helpful and alternative method for understanding molecular movement at the electrochemical interface.

Antifouling strategies for electrochemical sensing in complex biological media.

Surface fouling poses a significant challenge that restricts the analytical performance of electrochemical sensors in both in vitro and in vivo applications. Biofouling resistance is paramount to guarantee the reliable operation of electrochemical sensors in complex biofluids (e.g., blood, serum, and urine). Seeking efficient strategies for surface fouling and establishing highly sensitive sensing platforms for applications in complex media have received increasing attention in the past. In this review, we provide a comprehensive overview of recent research efforts focused on antifouling electrochemical sensors. Initially, we present a detailed illustration of the concept about biofouling along with an exploration of four key antifouling mechanisms. Subsequently, we delve into the commonly employed antifouling strategies in the fabrication of electrochemical sensors. These encompass physical surface topography (micro/nanostructure coatings and filtration membranes) and chemical surface modifications (PEG and its derivatives, zwitterionic polymers, peptides, proteins, and various other antifouling materials). The progress in antifouling electrochemical sensors is proposed concerning the antifouling mechanisms as well as sensing capability assessments (e.g., sensitivity, stability, and practical application ability). Finally, we summarize the evolving trends in the field and highlight some key remaining limitations.

Slow-Light-Enhanced Polarization Division Multiplexing Infrared Absorption Spectroscopy for On-Chip Wideband Multigas Detection in a 1D Photonic Crystal Waveguide.

Slow-light photonic crystal waveguide (PCW) gas sensors based on infrared absorption spectroscopy play a pivotal role in enhancing the on-chip interaction between light and gas molecules, thereby significantly boosting sensor sensitivity. However, two-dimensional (2D) PCWs are limited by their narrow mode bandwidth and susceptibility to polarization, which restricts their ability for multigas measurement. Due to quasi-TE and quasi-TM mode guiding characteristics in one-dimensional (1D) PCW, a novel slow-light-enhanced polarization division multiplexing infrared absorption spectroscopy was proposed for on-chip wideband multigas detection. The optimized 1D PCW gas sensor experimentally shows an impressive slow-light mode bandwidth exceeding 100 nm (TM, 1500-1550 nm; TE, 1610-1660 nm) with a group index ranging from 4 to 25 for the two polarizations. The achieved bandwidth in the 1D PCW is 2-3 times that of the reported quasi-TE polarized 2D PCWs. By targeting the absorption lines of different gas species, multigas detection can be realized by modulating the lasers and demodulating the absorption signals at different frequencies. As an example, we performed dual-gas measurements with the 1D PCW sensor operating in TE mode at 1.65 μm for methane (CH4) detection and in TM mode at 1.53 μm for acetylene (C2H2) detection. The 1 mm long sensor achieved a remarkable limit of detection (LoD) of 0.055% for CH4 with an averaging time of 17.6 s, while for C2H2, the LoD was 0.18%. This polarization multiplexing sensor shows great potential for on-chip gas measurement because of the slow-light enhancement in the light-gas interaction effect as well as the large slow-light bandwidth for multigas detection.

MOF-Enabled Electrochemical Sensor for Rapid and Robust Sensing of V-Series Nerve Agents at Low Concentrations.

Among nerve agents, V-series nerve agents are some of the most toxic, making low-concentration detection critical for the protection of individuals, populations, and strategic resources. Electrochemical sensors are ideally suited for the real-time and in-field sensing of these agents. While V-series nerve agents are inherently nonelectroactive, they can be hydrolyzed to electroactive products compatible with electrochemical sensing. Zr(IV) MOFs are next-generation nanoporous materials that have been shown to rapidly catalyze the hydrolysis of nerve agents. This work makes use of these nanomaterials to develop, for the first time, an MOF-enabled electrochemical sensor for V-series nerve agents. Our work demonstrates that the VX thiol hydrolysis product can be electrochemically detected at low concentrations using commercially available gold electrodes. We demonstrate that low-concentration thiol oxidation is an irreversible reaction that is dependent on both mass transport and adsorption. Demeton-S-methylsulfon, a VX simulant, is used to demonstrate the full range of sensor operation that includes hydrolysis and electrochemical detection. We demonstrate that MOF-808 rapidly, selectively, and completely hydrolyzes demeton-S-methylsulfon to less-hazardous dimethyl phosphate and 2-ethylsulfonylethanethiol. Low-concentration measurements of 2-ethylsulfonylethanethiol are performed by using electrochemical techniques. This sensor has a limit of detection of 30 nM or 7.87 μg/L for 2-ethylsulfonylethanethiol, which is near the nerve agent exposure limit for water samples established by the United States military. Our work demonstrates the feasibility of rapid, robust electrochemical sensing of V-series nerve agents at low concentrations for in-field applications.

Features of application of adaptive interferometric fiber sensors of acoustic emission to monitor the condition of polymer composite materials

The results of an experimental study of the operation of fiber optic sensors (FOS) of acoustic emission introduced into the structure of polymer composite materials (PCM) are presented. The reliability and fault tolerance of FOS under critical mechanical loads on PCM was assessed, and the influence of the presence of FOS embedded into the structure of PCM on the mechanical characteristics of the material was investigated. For demodulation of FOS output signals, the principles of adaptive holographic interferometry based on two-wave mixing at dynamic hologram formed in a photorefractive crystal are used.

An intelligent ratiometric fluorescent assay based on MOF nanozyme-mediated tandem catalysis that guided by contrary logic circuit for highly sensitive sarcosine detection and smartphone-based portable sensing application

As the well-known test-indicator for early prostate cancer (PCa), sarcosine (SA) is closely related to the differential pathological process, which makes its accurate determination increasingly significant. Herein, we for the first time expanded the peroxidase (POD)-like property of facile-synthesized Zn-TCPP(Fe) MOF to fluorescent substrates and exploited it to ratiometric fluorescent (RF) sensing. By harnessing the effective catalytic oxidation of MOF nanozyme toward two fluorescent substrates (Scopoletin, SC; Amplex Red, AR) with contrary changes, and target-responsive (SA + SOx)/MOF/(SC + AR) tandem catalytic reaction, we constructed the first MOF nanozyme-based RF sensor for the quantitative determination of SA. Superior to previous works, the operation of this RF sensor is under the guidance of AND-(AND^NAND) contrary logic circuit. The dual-channel binary output changes (from 1/0 to 0/1) not only enable the intelligent logical recognition of SA, bringing strengthened reliability and accuracy, but also manifest the proof-of-concept discrimination of PCa individuals and healthy ones. Through recording the fluorescence alterations of SC (F465) and AR (F585), two segments of linear relationships between ratiometric values (F585/F465) and varied contents of SA are realized successfully. The LOD for SA could reach to as low as 39.98 nM, which outperforms all nanozyme-originated SA sensors reported till now. Moreover, this sensor also demonstrates high selectivity and satisfactory performance in human serum samples. Furthermore, the portable sensing of SA is realized under the assistance of smartphone-based RGB analysis, demonstrating the potential of point-of-care diagnostics of PCa in the future.

Ultrahigh-speed imaging for high-impact concrete deformation analysis in pre- and post-cracking stages.

The evaluation of high-speed camera image sequence analysis results in concrete material testing under high-impact loading necessitates the consideration of the effect of the image quality on the measurement accuracy and thus on the potential of the geometric measurements derived from the image sequences. In this contribution, we evaluate the application potential of three ultrahigh-speed cameras with frame rates up to 10Mfps to analyze the deformation of concrete specimens before and after main crack formation in bending and compression tests. Specifically, we evaluate the Kirana 7M and Shimadzu HPV-X2 cameras with ISIS sensor architecture, and the Phantom TMX 7510 camera with BSI CMOS sensor technology. Three-point bending tests and split-Hopkinson pressure bar tests are performed on 160×40×40m m 3 cuboids and on 80mm long, 50mm diameter cylinders. Prior to main crack formation, the displacement vector field represents the specimen deformation, with higher values indicating the position where main cracks will initiate and propagate. Deformations of 80µm in 54µs for a bending test and of 154µm in 36.67µs for a compression test could be measured. The main cracks are then detected using displacement vector field discontinuity analysis techniques, and their evolution is followed to estimate the crack propagation velocity. Average velocities in bending tests between 603 and 854m/s have been determined over a time interval up to 40µs. An investigation of the camera sensor operation of the three optical devices is presented to assess their suitability for deformation analysis. Laboratory tests and real experimental results show that the quality of the propagation vector field, the crack detection, and the crack tip tracking are obviously affected by the image quality, but more significantly by the spatial and temporal resolution due to the small relative step deformations.

An autonomous Internet of Things spectral sensing system for in-situ optical monitoring of grape ripening: design, characterization, and operation

The present work proposes a novel autonomous Internet of Things (IoT) spectral sensing system for in-situ optical monitoring of grape ripening through reflectance signals. To this end, tailor-made hardware for this IoT end node was developed, characterized, and operated in both lab and field conditions. It included three complementary modules: the optical module, the host module, and the controller module. The optical module included four photodetectors and four LEDs with maximum emission wavelength centered at 530, 630, 690, and 730 nm that was placed in direct contact with the grape berry. The host module included the LED driver and the analog front-end for signal acquisition. Finally, the controller module provided full control of the system and ensured data storage, power management, and connectivity. The system was capable of measuring reflectance in the range of 4 – 100 % with a linear response (r2 > 998) and with a high reproducibility among different optical units. This design made it possible to collect reflectance signals from red (cv. Touriga Nacional) and white (cv. Loureiro) grape varieties in both lab and field environments. The relationship between this optical fingerprint (comprised of the different reflectance intensities recorded) and the evolution of grape berry quality parameters throughout the ripening period (for approximately two months), was analyzed and discussed. Lab data was used to establish a multivariate model based on Partial Least Squares for the prediction of the Total Soluble Solids (TSS) content in both varieties. The model error (Root Mean Square Error in Cross Validation) was 2.31 and 0.73 °Brix for Touriga Nacional and Loureiro, respectively. This model was applied to data acquired in the field in an illustrative example of the potential of the system to predict TSS in real time. The field observations collected during the monitoring period also provided relevant information about the potential issues that may occur during the unattended operation of the optical sensors. Additionally, the modular architecture of the optical module proposed makes it possible to use different LEDs and photodetectors, as well as the assembly of optical filters. This creates the possibility of using the same principles for measuring reflectance in different spectral ranges (e.g. IR) or even fluorescence. The results herein described paved the work for future developments of this technology that will include the development of prediction models for the most relevant grape ripening parameters based on reflectance data, as well as its operation as part of a Wireless Sensor Network.

Stability and reproducibility of solid electrolyte amperometry sensors at the analysis of hydrogen in nitrogen-containing gas mixtures

This paper illustrates the results of long-term tests on the stability of the output signal of the solid electrolyte amperometry sensor when measuring the hydrogen concentration in the H2 + N2 gaseous mixture. The obtained experimental data verify the stability and reproducibility of the sensor output signal for hydrogen concentration measurements in the nitrogen-containing gaseous mixture during > 8000 h of operation. The output signal drift, i.e., the limiting current value, was insignificant, less than ± 5 %. The sensor operation was performed at 3 temperature shifts with different time intervals; these changes did not have any impact either on the sensor integrity or on its operation. The structure of the solid electrolyte sensor, intermediate solid electrolyte / electrode layer and electrodes did not undergo any significant changes during operation. The dynamic characteristics of the sensor, the response time in particular, remained stable during the operation.

Compact, real-time exhaust gas recirculation rate sensor for use in natural gas combustion engine control

Natural gas fueled engines offer a 25% reduction in greenhouse gas emissions compared to diesel. However, achieving similar fuel efficiency to diesel while also minimizing harmful emissions is a challenge. Emissions and efficiency targets can be simultaneously achieved for natural gas by using a three way catalyst and exhaust gas recirculation (EGR), but this requires that the air-fuel ratio and EGR rate be measured and precisely controlled to avoid knocking combustion while maximizing efficiency. Such on-engine control can be achieved with high speed, precise, and robust measurements of EGR rate at a size and cost level compatible with onboard control systems. In this work, we present a compact, real-time laser absorption spectroscopy-based EGR sensor with potential for low-cost, on-engine control. We develop a new, computationally efficient data fitting algorithm called Integral Hashing to enable fully autonomous, low latency, real-time operation of the laser sensor at 954Hz. The complete sensor, including lasers and drivers, data acquisition, and data processing is contained in a single 25 × 25 × 8cm enclosure supplied with 15W of power. We validate the sensor to within 2% EGR rate against an extractive non-dispersive infrared (NDIR) gas sensor on a 250kW 6 cylinder natural gas engine by simultaneously measuring a set of steady state EGR rates between 0% and 25%. Additionally, we measure transient EGR rate fluctuations that are too fast to detect with the NDIR measurement. The sensor system presented here could be used to precisely control the EGR rate, improving the efficiency, emissions, and overall adoption of natural gas engines.

Drift-Like Effect Compensation for the Cyclic Temperature Operation of Semiconductor Gas Sensor

Drift-Like Effect Compensation for the Cyclic Temperature Operation of Semiconductor Gas Sensor

Stability and reproducibility of the amperometric sensors for oxygen concentration analysis in the nitrogen gas mixtures

The paper presents experimentally obtained results on the long-term stability tests of the solid electrolyte amperometric sensor output signal during the operation in the O2 + N2 gas mixtures. These data prove the stability and reproducibility of the output signal when measuring the oxygen concentration in air for 8000 hours. The output signal variation during the tests did not exceed ± 2 %. We performed four heating / cooling cycles of different durations, which did not influence either sensor integrity or operation characteristics. The structure of the solid electrolyte sensor and the solid electrolyte/electrode interfacial layer remained unchanged during the tests. Dynamic characteristics of the sensor, including the response time, were stable.

A Wireless Motion Sensor Operating Down to −28-dBm Energy Harvesting

A Wireless Motion Sensor Operating Down to −28-dBm Energy Harvesting

Highly Sensitive Phase-Variation Microwave Sensor Operating in Transmission Based on an Open Split Ring Resonator (OSRR)

Highly Sensitive Phase-Variation Microwave Sensor Operating in Transmission Based on an Open Split Ring Resonator (OSRR)

Эквивалент магнитного поля масс-спектрометра МИ 1201ИГ

This paper presents the development of an equivalent magnetic system that has similar characteristics to the electromagnet mass spectrometer MI-1201IG. This equivalent is intended for tuning the electronic blocks of the magnetic stabilization system of the mass spectrometer. Calculations of the distribution of the magnetic field of the electromagnet are carried out with the help of computer simulation and its parameters are determined, which are critical for the operation of sensors on the Hall effect in the air gap.