Monitoring In Harsh Environments Research Articles

Development and experimental evaluation of an acoustic flow meter prototype for measuring air flow

This study outlines the development and testing of a flow meter prototype specifically designed for use in nuclear reactor environments. The meter uses flow-induced vibration to measure flow rates and is designed for remote monitoring in harsh environments where radiation can damage electronics. The device generates a vibration signal produced by a feedback system when fluid flows out of an orifice and interacts with a downstream wedge. The frequency of the vibration signal corresponds directly to flow rate and velocity. The study investigates geometric parameters intrinsic to the prototype, such as orifice height, width, edge distance, and chamber length. Different configurations were also tested, including a bypass loop with variable cross-sections around the device. The investigation results reveal the impact of these geometric parameters on the vibration signal output, providing valuable insights for future design improvements and enhancing the effectiveness of flow metering systems used in nuclear reactor applications.

Vital parameter monitoring in harsh environment by the MedSENS in-ear multisensor device

Accurate assessment of vital parameters is essential for diagnosis and triage of critically ill patients, but not always feasible in out-of-hospital settings due to the lack of suitable devices. We performed an extensive validation of a novel prototype in-ear device, which was proposed for the non-invasive, combined measurement of core body temperature (Tc), oxygen saturation (SpO2), and heart rate (HR) in harsh environments. A pilot study with randomized controlled design was conducted in the terraXcube environmental chamber. Participants were subsequently exposed to three 15 min test sessions at the controlled ambient temperatures of 20 °C, 5 °C, and − 10 °C, in randomized order. Vital parameters measured by the prototype were compared with Tc measurements from commercial esophageal (reference) and tympanic (comparator) probes and SpO2 and HR measurements from a finger pulse-oximeter (reference). Performance was assessed in terms of bias and Lin’s correlation coefficient (CCC) with respect to the reference measurements and analyzed with linear mixed models. Twenty-three participants (12 men, mean (SD) age, 35 (9) years) completed the experimental protocol. The mean Tc bias of the prototype ranged between − 0.39 and − 0.80 °C at ambient temperatures of 20 °C and 5 °C, and it reached − 1.38 °C only after 15 min of exposure to − 10 °C. CCC values ranged between 0.07 and 0.25. SpO2 and HR monitoring was feasible, although malfunctioning was observed in one third of the tests. SpO2 and HR bias did not show any significant dependence on environmental conditions, with values ranging from − 1.71 to − 0.52% for SpO2 and 1.12 bpm to 5.30 bpm for HR. High CCC values between 0.81 and 0.97 were observed for HR in all environmental conditions. This novel prototype device for measuring vital parameters in cold environments demonstrated reliability of Tc measurements and feasibility of SpO2 and HR monitoring. Through non-invasive and accurate monitoring of vital parameters from the ear canal our prototype may offer support in triage and treatment of critically ill patients in harsh out-of-hospital conditions.

Eutectogel-based self-powered wearable sensor for health monitoring in harsh environments

Eutectogel-based self-powered wearable sensor for health monitoring in harsh environments

Amphibious epidermal area networks for uninterrupted wireless data and power transfer

The human body exhibits complex, spatially distributed chemo-electro-mechanical processes that must be properly captured for emerging applications in virtual/augmented reality, precision health, activity monitoring, bionics, and more. A key factor in enabling such applications involves the seamless integration of multipurpose wearable sensors across the human body in different environments, spanning from indoor settings to outdoor landscapes. Here, we report a versatile epidermal body area network ecosystem that enables wireless power and data transmission to and from battery-free wearable sensors with continuous functionality from dry to underwater settings. This is achieved through an artificial near field propagation across the chain of biocompatible, magneto-inductive metamaterials in the form of stretchable waterborne skin patches—these are fully compatible with pre-existing consumer electronics. Our approach offers uninterrupted, self-powered communication for human status monitoring in harsh environments where traditional wireless solutions (such as Bluetooth, Wi-Fi or cellular) are unable to communicate reliably.

Structural improvement of Sm–Mn oxides for enhanced CO sensing performance

Restricted by an insufficient understanding of the compositional and structural characteristics of the sensing materials that affect the sensing performances, the YSZ-based CO gas sensor remains in a dilemma in terms of further promoting sensitivity, selectivity and long-term stability. In this work, two bimetallic oxides with different crystal structures, perovskite SmMnO3 and mullite SmMn2O5, were prepared and adopted to elucidate the roles of the Mn3+, Mn4+ and surface oxygen vacancies. Compared with SmMnO3, the coexisting coordination modes of Mn3+ and Mn4+ in SmMn2O5 is conducive to generating oxygen vacancies. Furthermore, a SmMn2O5-based sensor with more oxygen vacancies demonstrates a relatively faster response/recovery speed and enhanced sensitivity of 2.05 times that of SmMnO3 under the same operation conditions. Such work may broaden insight into the development of efficient sensing materials that introduce oxygen vacancies through the construction of phase structures without complicated operations. Overall, the sensor attached to SmMn2O5 exhibits a low detection limit (5 ppm), a feasible response/recovery speed (24 s/28 s toward 40 ppm CO operating at 450 °C), satisfactory CO selectivity and long-term stability, highlighting its potential for CO monitoring in harsh environments.

Tough hydrogel–elastomer hybrids hydrophobically regulated by an MXene for motion monitoring in harsh environments

The introduction of MXene improves hydrophobic properties and enhance the hydrophobic encapsulation effect of a hydrogel. It can effectively prevent the influence of external moisture on the hydrogel, enabling outstanding sensing stability performance in harsh environments.

Beacon Synchronization-Based Multi-Channel With Dynamic Time Slot Assignment Method of WSNs for Mechanical Vibration Monitoring

Wireless Sensor Networks (WSNs) for mechanical vibration monitoring has been proposed for harsh environment monitoring purposes. However, links congestion makes the realization of reliable and energy-efficient transmission a challenge for such WSNs. To ease bandwidth pressure, a beacon synchronization-based multi-channel with dynamic time slot assignment method is proposed in this paper. Firstly, the network is separated into two opposing groups based on working state to maximize transmission performance. Secondly, the channel is allocated based on interference minimization from adjacent channels. To ensure the two opposing groups work individually, the nodes are synchronously triggered by transmission beacon, then nodes backoff and delay for a period of time to transmit data. Moreover, a dynamic timeslot assignment method is proposed to decrease channel collision. Finally, the experimental results demonstrate that the proposed methods can effectively schedule the network for data transmission via multi-channel, and the channel utilization performs better than CSMA/CA and TDMA.

Real-Time Monitoring System of Landslide Based on LoRa Architecture

The equal time interval sampling in the existing landslide monitoring system cannot detect the abnormal change of landslides in real time. This study proposes a novel landslide monitoring method based on the long range (LoRa) network and intelligent sensing Internet of Things (IoT) to address these drawbacks. The overall structure, hardware circuit, and software design of intelligent sensing monitoring technology are described comprehensively. The designed adaptive data collection strategy can effectively capture abnormal changes in the landslide monitoring parameters, which provides a better alternative monitoring scheme for the real-time data collection of disaster body status. Furthermore, it can ensure data accuracy for the research of intelligent large-scale landslide disaster monitoring and prediction. The field test demonstrates that the proposed system presents the technical characteristics of low power consumption, self-organizing network, stable and reliable communication, and long transmission distance, which is effective for mountain landslide monitoring in harsh environments.

Metrological Characterization of a High-Temperature Hybrid Sensor Using Thermal Radiation and Calibrated Sapphire Fiber Bragg Grating for Process Monitoring in Harsh Environments.

Fiber Bragg gratings inscribed in single crystalline multimode sapphire fibers (S-FBG) are suitable for monitoring applications in harsh environments up to 1900 °C. Despite many approaches to optimize the S-FBG sensor, a metrological investigation of the achievable temperature uncertainties is still missing. In this paper, we developed a hybrid optical temperature sensor using S-FBG and thermal radiation signals. In addition, the sensor also includes a thermocouple for reference and process control during a field test. We analyzed the influence of the thermal gradient and hotspot position along the sensor for all three detection methods using an industrial draw tower and fixed point cells. Moreover, the signal processing of the reflected S-FBG spectrum was investigated and enhanced to determine the reachable measurement repeatability and uncertainty. For that purpose, we developed an analytical expression for the long-wavelength edge of the peak. Our findings show a higher stability against mechanical-caused mode variations for this method to measure the wavelength shift compared to established methods. Additionally, our approach offers a high robustness against aging effects caused by high-temperature processes (above 1700 °C) or harsh environments. Using temperature-fixed points, directly traceable to the International System of Units, we calibrated the S-FBG and thermocouple of the hybrid sensor, including the corresponding uncertainty budgets. Within the scope of an over 3-weeks-long field trial, 25 production cycles of an industrial silicon manufacturing process with temperatures up to 1600 °C were monitored with over 100,000 single measurements. The absolute calibrated thermocouple () and S-FBG () measurements agreed within their combined uncertainty. We also discuss possible strategies to significantly reduce the uncertainty of the S-FBG calibration. A follow-up measurement of the sensor after the long-term operation at high temperatures and the transport of the measuring system together with the sensor resulted in a change of less than 0.5 K. Thus, both the presented hybrid sensor and the measuring principle are very robust for applications in harsh environments.

In-situ monitoring of micro-tunnel geometry change based on distributed optical fiber strain sensing

Underground radioactive waste disposal facilities must be monitored to guarantee their correct and safe exploitation during the early stage of their service life. This will be the case in Cigéo, the french industrial geological disposal facility for high-level and intermediate-level long-lived waste, which must be monitored for the first a hundred years at least. For this purpose optical fiber strain sensing cables can be chosen for their low intrusivity and resistance to harsh radiation environment. In this paper, a monitoring method able to follow shape evolution of the structure’s section, based on distributed strain sensing is tested on a high-level waste disposal cell mock-up, a steel lined micro-tunnel of 762 mm of outer diameter. The cell demonstrator is built in Meuse/Haute-Marne Underground Research Laboratory, in the same geological environment as the one envisaged for Cigéo but it is empty of waste. After 7 months of loading of the rock around the mock-up, a maximum of 2 mm of diameter reduction is observed with Rayleigh-scattering based strain sensing technique and 10 mm of spatial resolution around the circumference. This validation under realistic test conditions opens up to the use of the method in-situ for tunnel monitoring in harsh environment.

Intelligent Mobile Wireless Network for Toxic Gas Cloud Monitoring and Tracking.

Intelligent wireless networks that comprise self-organizing autonomous vehicles equipped with punctual sensors and radio modules support many hostile and harsh environment monitoring systems. This work’s contribution shows the benefits of applying such networks to estimate clouds’ boundaries created by hazardous toxic substances heavier than air when accidentally released into the atmosphere. The paper addresses issues concerning sensing networks’ design, focussing on a computing scheme for online motion trajectory calculation and data exchange. A three-stage approach that incorporates three algorithms for sensing devices’ displacement calculation in a collaborative network according to the current task, namely exploration and gas cloud detection, boundary detection and estimation, and tracking the evolving cloud, is presented. A network connectivity-maintaining virtual force mobility model is used to calculate subsequent sensor positions, and multi-hop communication is used for data exchange. The main focus is on the efficient tracking of the cloud boundary. The proposed sensing scheme is sensitive to crucial mobility model parameters. The paper presents five procedures for calculating the optimal values of these parameters. In contrast to widely used techniques, the presented approach to gas cloud monitoring does not calculate sensors’ displacements based on exact values of gas concentration and concentration gradients. The sensor readings are reduced to two values: the gas concentration below or greater than the safe value. The utility and efficiency of the presented method were justified through extensive simulations, giving encouraging results. The test cases were carried out on several scenarios with regular and irregular shapes of clouds generated using a widely used box model that describes the heavy gas dispersion in the atmospheric air. The simulation results demonstrate that using only a rough measurement indicating that the threshold concentration value was exceeded can detect and efficiently track a gas cloud boundary. This makes the sensing system less sensitive to the quality of the gas concentration measurement. Thus, it can be easily used to detect real phenomena. Significant results are recommendations on selecting procedures for computing mobility model parameters while tracking clouds with different shapes and determining optimal values of these parameters in convex and nonconvex cloud boundaries.

A langasite surface acoustic wave wide-range temperature sensor with excellent linearity and high sensitivity

Langasite (LGS) surface acoustic wave (SAW) temperature sensors have a large second order temperature coefficient of frequency, which leads to their non-linear and non-monotonic responses in a wide temperature range and possibly makes the measured temperatures non-unique for a specific sensor response. Here, we propose a high-temperature Pt/LGS SAW sensor with linear frequency–temperature behavior in a wide temperature range, which was fabricated on a LGS (0°, 138.5°, 72°) substrate. The sensor has a single acoustic mode, but dual resonances with similar second- and third-order temperature sensitivities that were utilized for achieving a linear frequency–temperature response by a method of difference. A linear relationship between the measured sensor output (Δfm21) and temperature was obtained in the range of −60 °C to 700 °C, consistent with the theoretical analysis. The sensor has a high sensitivity of −167 ppm/K for the whole temperature range. All the results demonstrated exciting prospects of the sensor for wide temperature monitoring in harsh environments.

Direct and Continuous Liquid-Level Sensing Using Gallium Nitride Ultraviolet Photodetectors

A liquid-level sensor using a gallium nitride (GaN) ultraviolet (UV) photodetector was successfully demonstrated. As the liquid level was changed, the intensity of UV light on the GaN surface was varied owing to the refraction of light on the liquid surface. For the fabrication of the liquid-level sensor, facile and rapid manufacturing was employed, involving metal wire bonding on the semiconductor surface. To characterize the fabricated sensor, the water level in the cylinder was measured according to the photocurrent change of the GaN UV photodetector. The responsivity of the liquid-level sensor depended on the diameter of the cylinder, applied voltage, and emission angle of the UV source. In particular, a cylinder diameter of 16 cm and an emission angle of 45° yielded a resolution of 0.05 cm up to the water level of 10 cm. The results of this study confirm the feasibility of liquid-level sensors for continuous and simultaneous liquid-level monitoring in harsh environments, including high-temperature plants, nuclear reactors, and chemical tanks.

Parallel structured fiber in-line multiple Fabry-Perot cavities for high temperature sensing

We propose and demonstrate a parallel structured fiber in-line interferometric device consisting of two sets of periodic internal mirrors which forms Fabry-Perot cavities with different cavity lengths. The output of the device contains two sets of overlapped fringe patterns, in which the main fringe peak is dominant and easy to identify. The cavity length of the internal mirror determines the spacing of the fringe peaks, which can be easily and flexibly controlled. The device is easy to operate or fabricated, simple in structure and exhibits high potential for high-temperature monitoring in harsh environments.

A wireless slot-antenna integrated temperature-pressure-humidity sensor loaded with CSRR for harsh-environment applications

In this study, a wireless slot-antenna integrated temperature-pressure-humidity (TPH) sensor loaded with complementary split ring resonator (CSRR) for harsh-environment applications was presented. The sensor is a multi-resonance structure with three separate resonant frequencies, which renders simultaneous measurements of temperature, pressure and humidity by placing sensitive elements in the corresponding CSRR structures. The sensitivity mechanisms for the temperature, pressure and humidity sensing are described in detail. The sensor was customized and fabricated on the high temperature co-fired ceramics (HTCC) using the three-dimensional co-firing and screen-printing technology. The humidity-sensitive graphene oxide modified polyimide (GO@PI) was used and characterized by the scanning electron microscope (SEM) and energy dispersive spectrometry (EDS). The as-prepared TPH sensor can stably work at the ambient environment of 25–300 ℃, 10–300 kPa, and 20–90 %RH. The temperature sensitivity of the TPH sensor is 133 kHz/℃. The frequency shift of the pressure sensor is 30 MHz with a highest sensitivity of 107.78 kHz/kPa at 60 %RH, and 300℃. The humidity sensor realizes a sensitivity of 389 kHz/%RH in the low humidity of 20–60 %RH and 1.52 MHz/%RH in the high humidity of 60–90 %RH at 10 kPa, and 25 ℃. The sensor described in this study has the advantages of simple structure, higher sensitivity, and lower environmental interference and has the potential for utilization in simultaneous TPH monitoring in harsh environments.

Hollow-Core Fiber-Based All-Fiber FPI Sensor for Simultaneous Measurement of Air Pressure and Temperature

In paper, an all-fiber Fabry-Perot interferometer (FPI) sensor with cascaded micro-cavities is presented to measure air pressure and temperature simultaneously. The proposed sensor mainly consists of two tiny segments of hollow-core fiber (HCF) located at the end of lead-in single mode fiber (SMF), and there is a misalignment fusion splicing between the two HCFs with different core diameter. The sensor has minor length of about $210~\mu \text{m}$ since the two HCFs lengths are about $80~\mu \text{m}$ and $130~\mu \text{m}$ , respectively. Because the reflection spectrum of the sensor is formed by the fiber cavity, air cavity and their combined cavity, which can be processed by methods of fast Fourier transform (FFT) and Fourier band-pass filter (FBPF), so we can analyze the corresponding responses of every cavity from the reflection spectrum of sensor for temperature and pressure variations. The experiment results show that the sensor has not only two different linear temperature sensitivities but also two different linear pressure sensitivities, which can be used to distinguish air pressure and temperature simultaneously. The validity experiment shows the relative errors of 1.0% and 1.4% are obtained in simultaneous measurements of air pressure and temperature. The advantages of the presented sensor than other structure sensors are miniaturization, easier to manufacture and with lower fabrication cost, which is promising used in the harsh environment monitoring.

Quadrature phase-stabilized three-wavelength interrogation of a fiber-optic Fabry-Perot acoustic sensor.

In this Letter, we propose a quadrature phase-stabilized three-wavelength demodulation technique for the interrogation of fiber-optic Fabry-Perot acoustic sensors. It is based on accurate and fast tuning of a monolithic modulated grating Y-branch laser. Three quadrature wavelengths are chosen to perform high-speed cavity length demodulation by wavelength switching, thereby avoiding imbalances and disturbances between the three optical paths in conventional three-wavelength quadrature phase-demodulation systems. A feedback-stabilization scheme for maintaining the quadrature phase condition is proposed for the first time, to the best of our knowledge, providing potential for long-term monitoring in harsh environments.

Femtosecond Laser Inscribed Multiple In-Fiber Reflection Mirrors for High-Temperature Sensing

We propose and demonstrate a high-temperature sensing device based on multiple reflection mirrors inscribed in optical fiber by femtosecond laser. The output spectrum of the device has a number of dominant wavelength peaks with controllable spacing and bandwidth formed by adjusting the reflection mirror separation. The device has excellent high-temperature sustainability up to 1100°C, good temperature sensitivity of 10.15 pm/°C and 16.92 pm/°C, within the temperature region between 100 and 400 °C, and between 400 and 1100 °C, respectively. The fiber device is simple in configuration, robust in structure, easy in fabrication and convenient in operation, and has high potential in sensing applications especially for high-temperature monitoring in harsh environment.

The performance simulation of the LiH-SiC-based Fast Neutron Detector for harsh environment monitoring using Geant4 and TCAD

In this work, Lithium Hydride (LiH) and Silicon Carbide (SiC) based sensor for fast neutron detection has been reported for the first time. LiH is used as a hydrogenous converter material for converting neutrons to charged particles (recoil protons) and wide band-gap semiconductor material SiC is employed as a charged particle sensing detector in the form of a Schottky Barrier Diode (SBD). Geant4 Monte-Carlo simulations have been performed for the optimization of the LiH converter layer thickness for different mono-energetic neutron sources as well as Am-Be standard neutron source. The optimization of LiH thickness is essential to attain the maximum neutron detection efficiency. The simulation study has revealed that the maximum neutron detection efficiency of ∼ 0.1% can be achieved at ∼800μm thickness of LiH for the Am-Be neutron source. Furthermore, a device simulation software (Silvaco TCAD) has been utilized to investigate the radiation-induced effects on the electrical characteristics of a SiC-based SBD detector. The gamma and neutron irradiation induced damage model has been developed from the experimental deep level defects information reported in the literature for the TCAD simulation study. The effects on different device parameters viz., ideality factor, Schottky barrier height, series resistance, built-in-potential, effective carrier concentration, image force lowering, carrier removal rate, etc., due to 60Co-gamma (dose=100 Mrad) and 1 MeV equivalent neutron irradiation (fluence up to 1016 neutrons/cm2) have also been reported. The 1 MeV equivalent neutron fluence is the fluence of 1 MeV neutrons producing the same damage in a detector material as induced by an arbitrary particle fluence with specific energy distribution. This model will be helpful in predicting the performance and behavior of the SiC-based devices which are subjected to heavy irradiation. The study reveals that the effect on the electrical characteristics of SiC-based SBD detectors is tolerable up to the fluence of 1015 neutrons/cm2 at room temperature, but preventive measures must be adopted to reduce the leakage current at elevated temperatures.

Design of a novel routing architecture for harsh environment monitoring in heterogeneous WSN

Wireless sensor network (WSN) has proved to be a hardcore desideratum for the continuous monitoring of hostile areas suffering from devastating forest fires, sudden volcanic eruptions, floods and many more. It can be contemplated by reviewing the state-of-the-art routing strategies, network instability and the delay incurred in data reception at the user end may lead to deplorable circumstances. In this study, a design of a novel routing architecture is proposed for harsh environment monitoring in heterogeneous WSN. It aims to ameliorate the stability period and network lifetime by shortening the communicative distance of nodes from the gateway node and by mitigating the hot-spot problem in the network. This architecture comprises of a network with multiple gateway nodes (MGNs) (four in this case), placed at equidistant from each other, outside the monitoring area. MGN is enriched with unlimited resources of energy, computation and coverage capabilities. The proposed MGN-based routing architecture (MRA) also improves the cluster head selection by incorporating node density factor along with energy and distance. Simulations show that MRA outperforms the state-of-the-art protocols, i.e. threshold-sensitive energy-efficient delay-aware routing protocol, Stable and Energy Efficient Clustering Protocol (SEECP), and Distance based Residual Energy-Efficient Stable Election Protocol (DRESEP) for two different cases of `nodes and energy' fractions at various performance metrics.