Field Sensor Research Articles

A Low-Cost Ultrasonic Sensor for Online Monitoring of Water Levels in Rivers and Channels

The measurement of flow parameters in rivers and channels is essential for anticipating floods, hydraulic modeling, and conducting water resource management studies. However, the high cost of existing equipment has resulted in a shortage of monitoring stations compared to actual requirements. This research focused on developing and validating a low-cost, highly accurate ultrasonic device that minimizes malfunctions for online monitoring of water levels in channels and streams. Considering the availability of components, cost, and the reported resolution of the product, the GY-Us42 sensor was selected for constructing the level gauge. The sensor operates within a range of 20 cm to 720 cm with a measurement accuracy of approximately 1 mm. The device integrates several error reduction mechanisms to enhance accuracy, including averaging multiple readings and temperature correction techniques. Laboratory data and field data gathered by both staff and shaft encoder were used for device validation. After constructing the main prototype and conducting various tests, multiple devices were installed in different locations within the Tehran rivers, and water depth data were collected over a specific period. Subsequently, data from other field sensors were also collected and used for device validation and accuracy assessment. The results indicate that the device's average error is below 3%, with a Root Mean Squared Error (RMSE) of 5.00 cm during field tests, demonstrates that the constructed device is an efficient tool for measuring water levels in streams, particularly during flood events.

Lignin-coated liquid metals-induced synthesis of deep eutectic solvent-based hydrogels with environmentally tolerant for strain sensors

In the work, alkali lignin (AL) was used as a coating layer for dispersing liquid metals (LM) in a ternary DES (choline chloride/ethylene glycol/water) system and generating free radical-catalyzed acrylic acid (AA) polymerization. The preparation of flexible sensors had high electrical conductivity (0.33 S·m-1), excellent self-healing and mechanical properties (84.7 KPa). The presence of AL facilitated the dispersion of LM in the DES system and the formation of a flexible hydrogel without the addition of an initiator. Moreover, DES was used as the liquid component of the PAA-AL2@LM2 hydrogel made it more environmentally tolerant and had better water retention. Even at -20 °C, the hydrogel exhibited low electrical resistance (131.4 Ω). The moisture loss of the prepared hydrogel was only 9% after 7 days at room temperature. This work exploited the significant advantages of DES and lignin-based materials in dispersing LM to provide a new technique for the preparation of metal-polymer composite hydrogels, which has great potential in the field of flexible sensors.

Mixed matrix membrane formation with porous metal–organic nanomaterials for CO2 capture and separation: A critical review

Due to the increasingly severe global warming trend, the reduction of CO2 emission and carbon capture have attracted growing interest. The separation of CO2 from gas mixtures, especially from point source and the atmosphere, is considered as one of the most important strategies for mitigating climate change. Porous metal–organic nanomaterials (PNMs), including metal-organic frameworks (MOFs) and metal-organic polyhedra (MOPs) have been extensively investigated in the fields of carbon capture, catalysts, sensors, biomedical imaging and gas storage. Their inherent pores, diverse surface function groups and potential modification possiblities make them competitive carbon capture materials. This review will introduce detailed scientific and technological advancements in PNMs and explain their fitness for carbon capture and separation, followed by the fabrication and application of mixed matrix membranes (MMMs) with PNMs. The current challenges appreared and solutions to improve the MMMs’ CO2 separation performance will also be stressed.

Probe-type optical fiber sensors for electric field distribution measurement

This paper reports a compact fiber optical electric field (E-field) sensor aiming for the precise detection of transient E-field distributions. Here, a reflective polarization-reciprocal optical path is proposed, which inherently mitigates the temperature-induced birefringence interference of the electro-optical crystal without the need for additional optical elements, thereby facilitating a reduced-size sensing probe. Furthermore, an adaptive particle swarm optimization (A-PSO) algorithm has been utilized for the first time to optimize the insulation structure of the optical E-field sensor, which significantly suppresses field distortion within the sensing region by 50%. This method addresses the technical gap in optical E-field sensor structure optimization, providing an effective means to improve its spatial resolution. The experimental results demonstrate that the proposed sensor exhibits a broad response frequency range from 50 Hz to 15 MHz, with a sensitivity of 0.675 V/kV cm−1. The proposed sensor successfully monitors the spatial distribution of electric fields in the lightning interception region of a lightning rod, thereby validating its effectiveness.

Flexible ceramic composites for Magnetic field sensor Applications

Flexible ceramic composites for Magnetic field sensor Applications

Lorentz Force Based Magnetic Field Sensor by Using Heterogeneous Integrated Optical Fiber With Side Nickel Core

Lorentz Force Based Magnetic Field Sensor by Using Heterogeneous Integrated Optical Fiber With Side Nickel Core

Non-contact power system fault diagnosis: a machine learning approach with electromagnetic current sensing

Modern power system protection schemes incorporate artificial intelligence (AI) techniques. However, in a conventional way, most of these schemes rely on the data of current and voltage collected from current transformer (CT) and potential transformer (PT) respectively. CTs suffer from the drawback of core saturation and impact the accuracy and effectiveness of intelligent methods. Also, it has the constraints of size, safety, and economy. The research here explores the effectiveness of magnetic sensors in advanced power system protection schemes as an alternative to traditional current sensing. In the presented work, a novel dataset is prepared by transforming transmission line currents into magnetic field components. Several supervised as well as unsupervised machine learning algorithms have been applied to this data instead of traditional currents and voltage for fault prediction. The paper discusses the comparative evaluation of these algorithms based on various performance metrices which reveals that Gaussian Naïve Bayes (GNB), K-nearest neighbor (KNN), random forest (RF), and extreme gradient boost (XGB) algorithms excel in fault detection, while multilayer perceptron (MLP) and KNN performs better fault classification. The findings promise the potential for developing compact, safe, and cost-effective protection schemes utilizing magnetic field sensors.

Novel Energy-efficient Modified LEACH Routing Protocol for Wireless Sensor Networks

Introduction: In wireless sensor networks (WSNs), hierarchical clustered routing protocols play a crucial role in minimizing energy consumption. The Low Energy Adaptive Clustering Hierarchy (LEACH) architecture is commonly employed for application-specific protocols in WSNs. However, the LEACH protocol may lead to increased energy consumption within the network if the rotational distribution of cluster heads (CHs) is not considered. Methods: A novel average energy, residual energy-based modified LEACH (aerem-LEACH) routing protocol for improving the WSN’s energy efficiency is proposed. This approach simultaneously considers the average energy of the networks and the residual node energy for routing, thereby reducing overall power consumption. Results: The suggested approach in aerem-LEACH accounts for optimal CHs numbers, and nodes in close proximity to the sink are forbidden from participating in cluster formation in order to achieve sufficient performance in the form of reduced sensor node energy consumption. Furthermore, a new threshold is employed in the proposed approach for selecting CHs for the network, and the aerem-LEACH uses free space, multiple hopping, and a hybrid communicating model for an energy-efficient network. Conclusion: The simulation result demonstrates that there is a substantial reduction in the consumption of energy in WSNs with the proposed aerem-LEACH routing protocol compared with existing routing protocols, namely Stable Energy Efficient Network (SEEN), Energy Efficient LEACH (EE LEACH), Optical LEACH (O-LEACH), LEACH-Mobile (LEACH-M), LEACHCentralized (LEACH-C), and LEACH for small-scale as well as large-scale sensor field.

Gold-coated silver nanorods on side-polished singlemode optical fibers for remote sensing at optical telecommunication wavelengths

The lower refractive index sensitivity (RIS) of plasmonic nanoparticles (NP) in comparison to their plasmonic thin films counterparts hindered their wide adoption for wavelength-based sensor designs, wasting the NP characteristic field locality. In this context, high aspect-ratio colloidal core-shell Ag@Au nanorods (NRs) are demonstrated to operate effectively at telecommunication wavelengths, showing RIS of 1720 nm/RIU at 1350 nm (O-band) and 2325 nm/RIU at 1550 nm (L-band), representing a five-fold improvement compared to similar Au NRs operating at equivalent wavelengths. Also, these NRs combine the superior optical performance of Ag with the Au chemical stability and biocompatibility. Next, using a side-polished optical fiber, we detected glyphosate, achieving a detection limit improvement from 724 to 85 mg/L by shifting from the O to the C/L optical bands. This work combines the significant scalability and cost-effective advantages of colloidal NPs with enhanced RIS, showing a promising approach suitable for both point-of-care and long-range sensing applications at superior performance than comparable thin film-based sensors in either environmental monitoring and other fields.

Quantum theory of a potential biological magnetic field sensor: Radical pair mechanism in flavin adenine dinucleotide biradicals

Recent studies in vitro and in vivo suggest that flavin adenine dinucleotide (FAD) on its own might be able to act as a biological magnetic field sensor. Motivated by these observations, in this study, we develop a detailed quantum theoretical model for the radical pair mechanism (RPM) for the flavin adenine biradical within the FAD molecule. We use the results of existing molecular dynamics simulations to determine the time-varying distance between the radicals on FAD, which we then feed into a quantum master equation treatment of the RPM. In contrast to previous semi-classical models, which are limited to the low-field and high-field cases, our quantum model can predict the full magnetic field dependence of the transient absorption signal. Our model's predictions are consistent with experiments at physiological pH values.

Gas sensing performance of Ti3C2Tx MXene heterojunction structures in greenhouse environments: a mini review

With the continuous advancement of smart greenhouse technologies, digital and information-based environmental monitoring has emerged as a focal point of research. The development of high-performance gas sensors is central to achieving this objective. In recent years, MXene materials have been widely applied in the field of gas sensors due to their excellent ion mobility, favorable hydrophilicity, outstanding electronic conductivity, and unique physicochemical properties. Various MXene heterojunction structures have been synthesized for gas detection. This review aims to summarize the current state of research on Ti3C2Tx-based gas sensors, explore methods for synthesizing different morphologies of Ti3C2Tx heterojunction structures, and evaluate the sensing behaviors of these configurations to fully harness their potential for gas monitoring in greenhouse environments. Additionally, an in-depth analysis of the sensing mechanisms associated with Ti3C2Tx heterojunction structures will be provided, offering theoretical support for future investigations. The findings indicate that Ti3C2Tx-based nanomaterials demonstrate considerable promise as high-performance sensors for gas detection in greenhouse settings. This innovative research not only provides new insights into the development of gas sensor technologies but also serves as an important foundation for the digitization of environmental monitoring.

Magnetoelectric effects in a heterostructure of magnetostrictive fiber composite and piezopolymer film

Abstract Magnetoelectric (ME) effects in composite heterostructures comprising ferromagnetic (FM) and piezoelectric (PE) layers realize mutual transformation of magnetic and electric fields and form the basis for the development of highly sensitive magnetic field sensors, electrically tuned electronic components, and energy harvesting devices. ME effects result from a combination of magnetostriction of the FM layer and piezoelectricity in the PE layer due to mechanical coupling between the layers. In this work ME effects are studied in a flexible heterostructure containing a magnetostrictive fiber composite (MFC) and a piezopolymer layer. MFC is a set of microwires made of amorphous FeCoSiB alloy with high magnetostriction and arranged in a plane parallel to each other in a polymer matrix. MFC exhibits strong in-plane anisotropy of magnetization and magnetostriction resulting from demagnetization effects in microwires. Anisotropy leads to the dependence of the linear and nonlinear ME effects characteristics on the orientation of dc magnetic field in the plane of the heterostructure. For the fabricated heterostructure at the resonance frequency of bending vibrations, a linear magnetoelectric coefficient of 24 V/(Oe∙cm) was obtained, and the efficiency of nonlinear generation of the second voltage harmonic reached 1.6 V/(Oe2∙cm). ME effects in MFC heterostructures can be used to create magnetic field sensors and electronics devices that are sensitive to the field orientation.electronics devices that are sensitive to the field orientation.

Potential NO2 gas-sensing performance of (Cr, Mo, W)-doped VO-Ti3C2O2-MXenes: a first-principles study

Abstract Typical Ti3C2O2 MXenes materials have been widely studied in the field of gas sensors due to their excellent properties in optoelectronics. The adsorption properties of four gases (NO2, NO, NH3, H2O) on the intrinsic Ti3C2O2, Ti3C2O2 with oxygen vacancy (VO-Ti3C2O2) and (Cr, Mo, W) doped VO-Ti3C2O2 were studied by density functional theory (DFT). The geometric structure, molecular dynamics, adsorption energy, differential charge density, and band structure of four gas molecules (NO2, NO, NH3, H2O) adsorbed in the intrinsic Ti3C2O2, VO-Ti3C2O2, and (Cr, Mo, W) doped VO-Ti3C2O2 were analyzed systematically. The results show that the adsorption energy and charge transfer properties of the VO-Ti3C2O2 doped with Cr, Mo, W are stronger than those of the intrinsic Ti3C2O2. Among them, the maximum adsorption energy of W-doped Ti3C2O2 for NO2 adsorption is −7.67 eV. Therefore, the inclusion of metal atoms in Ti3C2O2 material can improve the adsorption and selectivity of NO2 and other gases. In addition, W-doped Ti3C2O2 MXenes is a promising material for NO2 gas detection.

Engineering Nickel(II) Porphyrin-Conjugated Polymers with Different Aryl meso-Substituents for n-Type and p-Type Ammonia Sensors.

Conjugated polymers have revolutionized the field of conductometric gas sensors for sensing toxic gases arising from the fast urbanization and industrialization. In this work, we report the synthesis of a series of 5,15-diaryl Ni(II) porphyrin-conjugated polymers (pNiD(Aryl)P) and their integration as the top layer on an octafluorinated copper phthalocyanine (CuF8Pc) sublayer to construct bilayer heterojunction (BLH) devices for ammonia sensing. For the first time, we report the pioneering demonstration of polarity engineering within a BLH device by manipulating the meso-substituent of the 5,15-diaryl Ni(II) porphyrin-conjugated polymer constituting the top layer of the CuF8Pc/pNiD(Aryl)P BLH device. The BLH devices prepared from the 5,15-diaryl Ni(II) porphyrin-conjugated polymer bearing electron-donating meso-substituents as the top layer exhibit a p-type behavior, whereas an n-type behavior is observed for the BLH devices prepared from the 5,15-diaryl Ni(II) porphyrin-conjugated polymer bearing electron-withdrawing meso-substituents. Laser desorption ionization high-resolution mass spectrometry, UV/vis/NIR, and X-ray photoelectron spectroscopy studies provide evidence of a decrease in intramolecular dehydrogenative coupling in pNiD(Aryl)P bearing electron-withdrawing meso-substituents, resulting in low electrical conductivity of the thin films. Density functional theory calculations reveal noninvolvement of electron-withdrawing meso-substituents toward π-delocalization in the fused Ni(II) porphyrin tapes. Interestingly, all the CuF8Pc/pNiD(Aryl)P BLH devices exhibit remarkable sensing response toward NH3. Among all the devices, CuF8Pc/pNiDPP displays the highest sensitivity of -1.17% ppm-1 for NH3, whereas CuF8Pc/pNiDNapP and CuF8Pc/pNiDCNPP exhibit the best limit of detection for NH3, below 200 ppb. In addition, CuF8Pc/pNiDCNPP shows short response and recovery times of 13 and 255 s, respectively, making this device highly suitable for deployment in emergency services.

Flexible pressure sensor based on CNTs/CB/PDMS sponge with porous and microdome structures for sitting posture discrimination

The application fields of flexible pressure sensors are constantly expanding benefiting from their characteristics of being lightweight, flexible, easy to install, etc. Various structures have been developed for the purpose of improving the sensing performances of these sensors. However, the traditional structure designs typically enhance only a single aspect of performance. In this study, a flexible pressure sensor based on carbon nanotubes (CNTs)/carbon black (CB)/polydimethylsiloxane (PDMS) conductive sponge (CCPS) with both porous and microdome dual microstructures is prepared through the double template and swelling ultrasound methods. The introduction of two microstructures leads to the synergistic effect of dual sensing mechanisms, and the dual sensing mechanisms have been discussed according to the changes in microstructure morphology and finite element analysis results. Thanks to the synergistic effect of dual sensing mechanisms, CCPS exhibits comprehensive pressure sensing performances including a wide pressure sensing range of more than 350 kPa, high sensitivity under low pressure (7.10 kPa−1 over 0–25 kPa, 2.96 kPa−1 over 25–135 kPa, 1.09 kPa−1 over 135 kPa), and satisfactory long-term using performance of over 2000 cycles. CCPS is finally demonstrated for applications such as human motion detection, Morse code, and sitting position discrimination, indicating its broad application possibilities.

Highly responsive and stable room temperature acetic acid gas sensor based on nano-composite of MXene Ti3C2TX-NiCo2O4-MnO2

Designing novel acetic acid gas sensors is highly imperative for human health. Two-dimensional (2D) layered MXene Ti3C2Tx is becoming an emerging and promising material in gas sensing. In this manuscript, the hydrothermal method was used to synthesize MXenes Ti3C2Tx/Nb2CTx supported NiCo2O4-MnO2 composites and pure materials. The structure, chemical composition and morphology of the samples were studied by SEM, EDS, TEM, HRTEM, XRD, BET, FTIR, UV–visible, XPS and Raman, justifying the successful synthesis of products. The layered structure of Ti3C2Tx enhanced the BET surface area and provided sufficient sites, which assisted the gas sensing improvement. The gas sensors were fabricated from synthesized products and were tested for different kinds of VOCs deeply. The results exposed that the gas sensor of Ti3C2Tx-NiCo2O4-MnO2 (5 % of Ti3C2Tx = NCO-Mn-Ti-5) was highly sensitive to 20 ppm acetic acid and very less responsive to all other VOCs (acetone, TMA, ethanol, methanol, formaldehyde, acetaldehyde, acetylene and xylene) at room temperature. The response (Rg/Ra) to 20 ppm acetic acid was 12.5 and the lowest detection limit was 0.05 ppm. Additionally, the sensor of NCO-Mn-Ti-5 revealed great stability/reproducibility, short response/recovery times and linearity between acetic acid concentration and response. The idea of the novel sensor (NCO-Mn-Ti-5) could be potentially useful in the field of sensors.

High-sensitivity lossy mode resonance sensor by deposition of perovskite nanofilms on the eccentric core quasi D-shaped photonic quasi-crystal fiber

Lossy mode resonance (LMR) sensors have garnered widespread attention in recent years. This work proposes a quasi-D-shaped eccentric core photonic quasi-crystal fiber LMR (PQF-LMR) sensor with an M-type perovskite coating surface. The sensor is based on a ten-fold Penrose PQF structure, featuring four kinds of air holes and perovskite coating deposited on the micro-groove surface. The sensing characteristics are analyzed using the finite element method. The results indicate that multiple LMRs can be excited in both Y-polarization and X-polarization. The 2 nd and 3 rd lossy modes exhibit outstanding performance in terms of sensitivity and figure of merit (FOM). The 2 nd lossy mode achieves a maximum sensitivity of 84,985 nm/RIU and an average sensitivity of 46,358 nm/RIU. In the 3 rd lossy mode, the maximum FOM reaches 904.34 RIU−1. For comparison, the quasi-D-shaped PQF-LMR sensor with a flat surface is also investigated. The PQF-LMR sensor with perovskite coating demonstrates superior sensing performance and significantly broadens the prospects for LMR sensors in various fields.

A compact and mobile stray-field NMR sensor

In this paper, we introduce a compact, single-sided stray field sensor for NMR relaxometry applications. The sensor consists of four main components: the magnet, the RF coil, the spectrometer, and the translation stage. Our proposed magnet, an improved design of the Profile NMR−MOUSE, is designed for low weight, compactness, and magnetic field homogeneity, achieved through various shim strategies using a mixed genetic algorithm. The magnet comprises eight NdFeB blocks, generating a magnetic field of 0.424T within the sensitive region, positioned 12 mm above the magnet surface. For high spatial resolution measurements, we optimized the sensor performance by using a custom-designed rf coil, providing maximum sensitivity, lateral selectivity, and a dead time of less than 20µs. Moreover, we utilized 3D-printed structures to precisely align the sensitive slice within the object, using an experimental approach based on CPMG measurements. The presented setup achieved a spatial resolution of 50µm, with resolution changes proportional to acquisition time. We demonstrate the sensor’s versatility and high resolution with measurements on materials such as cosmetics, elastomers, glue, and wood, verifying the good performance of our design, our alignment strategy, and the measuring scheme.

Highly sensitive fiber vector magnetic field sensor based on an open-cavity Mach-Zehnder interferometer filled with magnetic fluid

In this paper, we proposed and demonstrated a highly sensitive fiber vector magnetic field sensor utilizing an open-cavity Mach-Zehnder interferometer (MZI) filled with magnetic fluid. The MZI sensor was fabricated using large-offset splicing technique to form an open cavity, facilitating the easy introduction of magnetic fluid samples into the open cavity. The MZI sensor was then encapsulated in a glass capillary containing diluted magnetic fluid. As the applied magnetic field varies, the refractive index of the magnetic fluid undergoes a corresponding change, subsequently inducing a shift in the transmission spectrum of the MZI. By monitoring the wavelength shift of the transmission spectrum, we can accurately detect the intensity of the magnetic field. The proposed sensor can achieve vector magnetic field measurement because of the axially asymmetric open-cavity MZI. The maximum sensitivity to magnetic field direction is 0.260 nm/°. Notably, the proposed sensor achieves an ultrahigh sensitivity, reaching an value of −17.306 nm/mT within the range of 4 mT to 7 mT. In addition, a temperature sensitivity of 2.236 nm/℃ is obtained within the temperature range of 30 ℃ to 65 ℃. Given its advantages, including high sensitivity, compact size and low cost, our MZI sensor holds immense potential for diverse applications in magnetic field measurement.

Large field of view Shack-Hartmann wavefront sensor based on high-density lens transfer function retrieval

Large field of view Shack-Hartmann wavefront sensor based on high-density lens transfer function retrieval