Harsh Environment Sensors Research Articles

Investigation and experiment of high shock packaging technology for High-G MEMS accelerometer

High-G MEMS accelerometer (HGMA) has applications in aerospace, explosive and penetrative environments, and so on. Reliable encapsulation is the basis of ensuring the survival and function of the sensor in harsh environments, but complete high-g accelerometer sensor encapsulation models are rarely reported. We use a multiple-degree-of-freedom system and the theory of stress wave interface transfer to design and analyze three different packaging methods for high-g accelerometer sensors. We also determine the best encapsulation method by establishing natural frequency calculation and stress wave transfer models between media. The stress wave reflection ability of patch adhesive is verified with a split Hopkinson pressure bar (SHPB). The results indicate that the unloading efficiency of patch adhesive to the stress wave is up to 95%. The HGMA frequency response is greater than 300 kHz, which was measured by a single Hopkinson rod. The anti-impact performance and the measurement accuracy in the ultra-high overload environment of the high-g acceleration sensor were verified by artillery penetration tests. The results show that the sensor can realize high precision measurements under ultra-high overload environments (the measuring accuracy of the sensor under the impact of 200,000 g is better than 5%).

Durable shape sensor based on FBG array inscribed in polyimide-coated multicore optical fiber.

The paper presents a novel three-dimensional quasi-continuous shape sensor based on an FBG array inscribed by femtosecond laser pulses into a 7-core optical fiber with a polyimide protective coating. The measured bending sensitivity of individual FBGs ranges from 0.046 nm/m-1 to 0.049 nm/m-1. It is shown that the sensor allows for reconstructing 2- and 3-dimensional shapes with high accuracy. Due to the high value of the core aperture and individual calibration of each FBG we were able to measure the smallest reported bending radii down to 2.6 mm with a record accuracy of ∼1%. Moreover, we investigate the magnitude of the errors of curves reconstruction and errors associated with measurement of curvature radii in the range from 2.6 to 500 mm. The main factors affecting the accuracy of measurements are also discussed. The temperature resistance of both the inscribed FBG structures and of the protective coating, along with the high mechanical strength of the polyimide, makes it possible to use the sensor in harsh environments or in medical and composite material applications.

Nanostructured sapphire optical fiber embedded with Au nanorods for high-temperature plasmonics in harsh environments.

Sensors for harsh environments must exhibit robust sensing response and considerable thermal and chemical stability. We report the exploration of a novel all-alumina nanostructured sapphire optical fiber (NSOF) embedded with Au nanorods (Au NRs) for plasmonics-based sensing at high temperatures. Temperature dependence of the localized surface plasmon resonance (LSPR) of Au NRs was studied in conjunction with numerical calculations using the Drude model. It was found that LSPR of Au NRs changes markedly with temperature, red shifting and increasing in transmission amplitude as the temperature increases. Furthermore, this variation is highly localized through tunneling by overlapping the near-field of thin cladding and sapphire optical fiber. The NSOF embedded with Au NRs has the potential for sensing in advanced energy generation systems.

Finite element analysis of polysilicon based MEMS temperature-pressure sensor

Temperature and pressure sensor, both are in high demand for industrial application but to use pressure sensor in harsh environment is a challenging task. As many of the semiconductor devices have low tolerance to heat and device failed to work. To overcome the failure of the device, many attempts have been taken by researches. The one cost effective and efficient method is utilization of polysilicon material. In this paper, we investigate the opportunity of utilizing p-polysilicon for temperature-pressure sensor. To better understand the effect of pressure on resistors the device has been designed and modelled using finite element analysis and virtual fabrication process of proposed sensor has also been shown. The finite element analysis shows the cause of variation in sensitivity and temperature drift due to the influence of pressure. The sensors have been loaded under the pressure ranging from 10 to 100 psi within the temperature range from −40 °C to 60 °C. The sensitivity of proposed model was found to be ∼1.063 mv/psi. The change in resistance for lower pressure shows a drift in output curves while for higher pressure the output curves varies linearly with respect to temperature. The TCR value of designed pressure sensor was found to be ∼5.477 × 10−3(°C)−1.

Fatigue Performance of Type I Fibre Bragg Grating Strain Sensors.

Although fibre Bragg gratings (FBGs) offer obvious potential for use in high-density, high-strain sensing applications, the adoption of this technology in the historically conservative aerospace industry has been slow. There are several contributing factors, one of which is variability in the reported performance of these sensors in harsh and fatigue prone environments. This paper reports on a comparative evaluation of the fatigue performance of FBG sensors written according to the same specifications using three different grating manufacturing processes: sensors written in stripped and re-coated fibres, sensors written during the fibre draw process and sensors written through fibre coating. Fatigue cycling of the fibres is provided by a customized electro-dynamically actuated loading assembly designed to provide high frequency and amplitude loading. Pre- and post-fatigue microscopic analysis and high-resolution transmission and reflection spectra scanning are conducted to investigate the fatigue performance of FBGs, the failure regions of fibres as well as any fatigue-related effects on the spectral profiles. It was found that because of the unique fabrication method, the sensors written through the fibre coating, also known as trans-jacket FBGs, show better fatigue performance than stripped and re-coated FBGs with greater control possible to tailor the optical reflection properties compared to gratings written in the draw tower. This emerging method for inscription of Type I gratings opens up the potential for mass production of higher reflectivity, apodised sensors with dense or complex array architectures which can be adopted as sensors for harsh environments such as in defence and aerospace industries.

Exploration of Pinned Photodiode Radiation Hardening Solutions Through TCAD Simulations

The use of pinned photodiode (PPD)-based CMOS image sensors (CIS) in harsh radiation environment (such as space) is limited by their tolerance to ionizing radiation. Technology computer-aided design (TCAD) simulations are performed to reproduce the radiation-induced defect and therefore the dark current increase in PPD pixels up to 1 kGy (i.e., 100 krad) of total ionizing dose (TID). To do so, the TCAD models are calibrated with measurements performed on irradiated pixels. Then, the influence on the PPD radiation hardness of various manufacturing process and pixel design modifications are explored. This work shows that the proposed modification can improve the radiation hardness of PPD CIS against ionizing.

A review of principles of MEMS pressure sensing with its aerospace applications

PurposePressure, being one of the key variables investigated in scientific and engineering research, requires critical and accurate measurement techniques. With the advancements in materials and machining technologies, there is a large leap in the measurement techniques including the development of micro electromechanical systems (MEMS) sensors. These sensors are one to two orders smaller in magnitude than traditional sensors and combine electrical and mechanical components that are fabricated using integrated circuit batch-processing technologies. MEMS are finding enormous applications in many industrial fields ranging from medical to automotive, communication to electronics, chemical to aviation and many more with a potential market of billions of dollars. MEMS pressure sensors are now widely used devices owing to their intrinsic properties of small size, light weight, low cost, ease of batch fabrication and integration with an electronic circuit. This paper aims to identify and analyze the common pressure sensing techniques and discuss their uses and advantages. As per our understanding, usage of MEMS pressure sensors in the aerospace industry is quite limited due to cost constraints and indirect measurement approaches owing to the inability to locate sensors in harsh environments. The purpose of this study is to summarize the published literature for application of MEMS pressure sensors in the said field. Five broad application areas have been investigated including: propulsion/turbomachinery applications, turbulent flow diagnosis, experimentalaerodynamics, micro-flow control and unmanned aerial vehicle (UAV)/micro aerial vehicle (MAV) applications.Design/methodology/approachThe first part of the paper deals with an introduction to MEMS pressure sensors and mathematical relations for its fabrication. The second part covers pressure sensing principles followed by the application of MEMS pressure sensors in five major fields of aerospace industry.FindingsIn this paper, various pressure sensing principles in MEMS and applications of MEMS technology in the aerospace industry have been reviewed. Five application fields have been investigated including: Propulsion/Turbomachinery applications, turbulent flow diagnosis, experimental aerodynamics, micro-flow control and UAV/MAV applications. Applications of MEMS sensors in the aerospace industry are quite limited due to requirements of very high accuracy, high reliability and harsh environment survivability. However, the potential for growth of this technology is foreseen due to inherent features of MEMS sensors’ being light weight, low cost, ease of batch fabrication and capability of integration with electric circuits. All these advantages are very relevant to the aerospace industry. This work is an endeavor to present a comprehensive review of such MEMS pressure sensors, which are used in the aerospace industry and have been reported in recent literature.Originality/valueAs per the author’s understanding, usage of MEMS pressure sensors in the aerospace industry is quite limited due to cost constraints and indirect measurement approaches owing to the inability to locate sensors in harsh environments. Present work is a prime effort in summarizing the published literature for application of MEMS pressure sensors in the said field. Five broad application areas have been investigated including: propulsion/turbomachinery applications, turbulent flow diagnosis, experimental aerodynamics, micro-flow control and UAV/MAV applications.

Design Optimization of a Double-Stage Resolver

Accurate position estimation is an integral part of any motion control system. Besides, instantaneous position of poles plays an important role in electronic drive system of modern PM machines. Resolvers, due to their structure, are the most reliable position sensors in harsh environments. However, resolvers are not as accurate as optical encoders in normal conditions. To increase the accuracy of these sensors, various solutions are used, such as optimization in winding arrangement, rotor and stator contour, slot–pole combinations, and improvements in resolver-to-digital converter. In this paper, fractional slot concentrated winding is used in an axial flux resolver. By the aid of winding function approach, it is shown that increasing the coil pitch improves the estimated position accuracy. The theory is tested for double-layer and four-layer windings with different displacement angles. A new double-stage resolver is also introduced. The proposed structure, in which a meta-heuristic algorithm determines the slot dimensions, the number of turns, and the displacement angle between the stages, results in lower total harmonic distortion of output voltage and, consequently, lower estimated position error. The theoretical and analytical expressions are verified by a three-dimensional time stepping finite element analysis and experimental results. Good agreement between simulation and experimental results validate the advantages of the optimized resolver.

Sensing Performance of Nanocrystalline Graphite-Based Humidity Sensors

Environmental sensors play a crucial role in a wide range of applications. Among them, humidity sensors that are stable and operational in harsh environments are incredibly important for process control and monitoring. Nanocrystalline graphite (NCG) is a type of carbon-based thin film material. Previous work has shown that NCG has excellent mechanical properties and is able to withstand high radiation doses. The granular structure of the NCG film makes it a good candidate for humidity sensing as the film consists of conductive graphitic grains with a high density of sp <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> bonds and amorphous grain boundaries with high resistivity, and adsorption of water molecule onto the film forms conductive pathways between grains through the Grotthuss mechanism which lowers the resistance of the film by a measurable amount. Here, we report for the first time a working humidity sensor with linear response, fabricated using NCG as the sensing material for harsh, real-world environments, which include exposure to weak acids via rainfall, UV radiation, mechanical wear, and high-humidity environments. The calculated sensitivity of the best-fabricated sensor is S = 0.0334%, with a maximum resistance change of -4.4 kg, over the range of 15% RH to 85% RH. The response time of the sensor is 20 ms with the current measurement setup. The baseline resistance value of the sensor at 15% RH is 210 kg. The sensor has the potential to be used as a humidity sensor for harsh environments due to the chemical, thermal, and mechanical stability of the NCG film.

Plasmonic Conducting Metal Oxide-Based Optical Fiber Sensors for Chemical and Intermediate Temperature-Sensing Applications.

The demand for real-time sensors in harsh environments at elevated temperature is significant and increasing. In this manuscript, the chemical and temperature sensing using the optical response through the practical fiber platform is demonstrated, and principle component analysis is coupled with targeted experimental film characterization to understand the fundamental sensing layer properties, which dominate measured gas sensing responses in complex gas mixtures. More specifically, tin-doped indium oxide-decorated sensors fabricated with the sol-gel method show stable and stepwise transmission responses varying over a wide range of H2 concentration (5-100%) at 250-350 °C as well as responses to CH4 and CO to a lesser extent. Measured responses are attributed to modifications to the surface plasmon resonance absorption in the near-infrared range and are dominated by the highest concentrations of the most-reducing analyte based upon systematic mixed gas stream experiments. Principal component analysis is utilized for this type of sensor to improve the quantitative and qualitative understanding of responses, clearly identifying that the dominant principle component (PC #1) accounts for ∼78% of total data variance. Correlations between PC #1 and the experimentally derived free carrier concentration confirm that this material property plays the strongest role on the ITO gas sensing mechanism, while correlations between the free carrier mobility and the second most important principle component (PC #2) suggest that this quantity may play a significant but secondary role. As such, the results presented here clarify the relationship between generalized principle components and fundamental sensing materials properties thereby suggesting the pathway toward improved multicomponent gas speciation through sensor layer engineering. The work presented represents a significant step toward the ultimate objective of optical waveguide sensors integrated with multivariate data analytics for multiparameter monitoring with a single sensor element.

A Room-Temperature CNT/Fe₃O₄ Based Passive Wireless Gas Sensor.

A carbon nanotube/Fe3O4 thin film-based wireless passive gas sensor with better performance is proposed. The sensitive test mechanism of LC (Inductance and capacitance resonant) wireless sensors is analyzed and the reason for choosing Fe3O4 as a gas sensing material is explained. The design and fabrication process of the sensor and the testing method are introduced. Experimental results reveal that the proposed carbon nanotube (CNT)/Fe3O4 based sensor performs well on sensing ammonia (NH3) at room temperature. The sensor exhibits not only an excellent response, good selectivity, and fast response and recovery times at room temperature, but is also characterized by good repeatability and low cost. The results for the wireless gas sensor’s performance for different NH3 gas concentrations are presented. The developed device is promising for the establishment of wireless gas sensors in harsh environments.

Fiber In-Line Mach–Zehnder Interferometer for Gas Pressure Sensing

A Mach–Zehnder interferometer based on double off-axis twisted deformation on single mode fiber (SMF) is proposed and experimentally demonstrated for gas pressure measurements. The off-axis twisted deformation is achieved by twisting a SMF under continuous arc discharging. An open air-gap was created on the cladding of the SMF between the two off-axis deformation points by using a femtosecond laser. The cladding modes transmit through the air-gap whose refractive index is directly determined by the air pressure. The interferometer is applied for high-sensitive pressure sensing with a sensitivity of −5.183 nm/MPa and temperature cross-sensitivity of 13.3 kPa/°C. Consequently, the open air-gap added MZI structure can therefore be considered an excellent candidate as a gas pressure sensor in harsh environments due to its low cost, compact size, ease of fabrication, and all-fiber configuration.

A Novel Metamaterial Inspired High-Temperature Microwave Sensor in Harsh Environments.

A high-temperature sensor based on a metamaterial unit cell is proposed in this paper. The wireless passive temperature sensing method is based on the electromagnetic backscatter principle, and thus has the advantages of higher quality, lower environmental interference, and anti-low frequency interference. We developed a finite-element method-based model for the sensor via high-frequency simulation software (HFSS). A double split-ring resonator (SRR) with an outer ring length of 13 mm was designed on alumina ceramic substrate. The sensor was fabricated at 2.42 GHz using micromechanical technology and screen printing technology. When the temperature increased from 28 to 1100 °C, the resonant frequency decreased from 2.417 to 2.320 GHz with an average sensitivity of 95.63 kHz/°C. As the sensor is easily designed and fabricated, it can be used for chipless radio frequency identification (RFID) tags by simply changing the size of rings. Furthermore, emerging 3D printing technology and commercial desktop inkjet printers will be used to realize the rapid low-cost preparation of the sensor, enabling its wide range of applications in aerospace, military, manufacturing, transportation, and other fields.

Fibre optical sensors for harsh gas turbine environments

Four selected applications of fibre optical sensors in industrial gas turbines will be reviewed. The measurement challenges, the operating principle of the corresponding fibre optical sensing solution and associated test results will be described.

Temperature Monitoring and Flow Estimation in Electrolytic Cells Using Wireless Harsh Environment Sensors

Proper control of temperature and electrolyte circulation flow is mandatory in electrolytic cells to produce dense and high-purity cathodes. The electrochemical kinetics of cells is inherently dependent on these electrolyte variables. Continuous monitoring of electrolyte condition allows enhancing cathode quality, electrodeposition time, better utilization of electrolyte additives, early identification of temperature excursions, and electrolyte flow blockages. Abnormal cell conditions can produce excessive evaporation, higher energy consumption, anode passivation that impair cathode production in copper electrorefining, and safety issues because the production of flammable hydrogen in copper electrowinning. Therefore, the monitoring of changes in temperature and electrolyte flow can give critical indicators of process deviations. With real-time information about electrolyte variables, it is possible to provide early warnings to face the wide variability of cell performance and safety conditions caused by electrolyte condition mismanagement. This paper proposes a noninvasive wireless sensor for monitoring the electrolyte temperature inside cells and estimates the electrolyte circulation flow through each cell simultaneously. The sensor design is suitable to highly corrosive sulfuric acid environments. The condition-monitoring sensor proposed is small in size, lightweight, and meets battery-free operation and nonsparking safety requirements. It uses an inductive link-based system for powering and a radio frequency-link for communicating. The result is a sensor that surpasses the features of standard instrumentation not suitable for electrolytic process monitoring.

A big data driven analytical framework for energy-intensive manufacturing industries

Abstract Energy-intensive industries account for almost 51% of energy consumption in China. A continuous improvement in energy efficiency is important for energy-intensive industries. Cleaner production has proven itself as an effective way to improve energy efficiency and reduce energy consumption. However, there is a lack of manufacturing data due to the difficult implementation of sensors in harsh production environment, such as high temperature, high pressure, high acid, high alkali, and smoky environment which hinders the implementation of the cleaner production strategy. Thanks to the rapid development of the Internet of Things, many data can be sensed and collected in the manufacturing processes. In this paper, a big data driven analytical framework is proposed to reduce the energy consumption and emission for energy-intensive manufacturing industries. Then, two key technologies of the proposed framework, namely energy big data acquisition and energy big data mining, are utilized to implement energy big data analytics. Finally, an application scenario of ball mills in a pulp workshop of a partner company is presented to demonstrate the proposed framework. The results show that the energy consumption and energy costs are reduced by 3% and 4% respectively. These improvements can promote the implementation of cleaner production strategy and contribute to the sustainable development of energy-intensive manufacturing industries.

Substrate Integrated Waveguide (SIW)-Based Wireless Temperature Sensor for Harsh Environments

This paper presents a new wireless sensor structure based on a substrate integrated circular waveguide (SICW) for the temperature test in harsh environments. The sensor substrate material is 99% alumina ceramic, and the SICW structure is composed of upper and lower metal plates and a series of metal cylindrical sidewall vias. A rectangular aperture antenna integrated on the surface of the SICW resonator is used for electromagnetic wave transmission between the sensor and the external antenna. The resonant frequency of the temperature sensor decreases when the temperature increases, because the relative permittivity of the alumina ceramic increases with temperature. The temperature sensor presented in this paper was tested four times at a range of 30–1200 °C, and a broad band coplanar waveguide (CPW)-fed antenna was used as an interrogation antenna during the test process. The resonant frequency changed from 2.371 to 2.141 GHz as the temperature varied from 30 to 1200 °C, leading to a sensitivity of 0.197 MHz/°C. The quality factor of the sensor changed from 3444.6 to 35.028 when the temperature varied from 30 to 1000 °C.

Thin and Thick Film Ceramic-Based Passive Wireless Temperature Sensors for Harsh Environments

The needs for real-time temperature monitoring of energy systems in extreme conditions keeps increasing due to the growth of manufacturing industries. Current technologies utilize thermocouples, infrared laser interferometers, and surface acoustic wave (SAW) sensors. Thermocouples have limited lifespan. The reliability is poor due to continuous redox reaction taking place at the hot junction and any caustic environment will corrode the thermocouple material. Laser interferometers are limited by the spot area of the laser beam and monitoring temperature gradient is difficult, since it is a surface sensitive technique. To overcome the limitations, research has been focused on passive wireless sensor technology where an inductor–capacitor (LC) circuit was used to monitor the temperature and local strain conditions. The primary objective of this work was to study the materials properties of carbide/silicide and oxide composites for the fabrication of ceramic-based LC circuits on a ceramic substrate using thin and thick film deposition methods. This work includes the investigation of the composite precursor, pattern technology and the effect of thermal processing on the final pattern and stability. The relation of volume shrinkage during sintering process and phase development are of interest. The secondary objective of this work was to investigate the electrical properties of the tailored sintered electrodes. One system that will be discussed is the development of a polymer-derived electroceramic electrodes based on two different carbide/silicide compositions. These inks were synthesized by mixing a siloxane/silane compound with an active inorganic filler material. Upon sintering, the organic molecules decomposed and the silicon will react with the inorganic fill at a higher temperature to form a ceramic composite. The reaction kinetics depends on the reaction between terminating functional groups, silicon ``atom, and the filler particle. To understand the reaction kinetics, phase formation, and other mechanical properties (such as volumetric shrinkage), varying ratios of the particle filled polymer matrix was injection molded and sintered at varying temperature rates. The compositions that provided the desired material properties was chosen to direct-write the LC circuit pattern on a ceramic substrate by a 2D printing technology and screen printing technology. The sintered sensor was characterized by XRD, SEM and the electrical characterization of the printed LC circuits were completed on the sensor compositions by a signal analyzer in tandem with an oscilloscope (at temperatures 50-1300oC). Miniaturization of the LC circuit was developed by a thin film deposition process to show the effect of size reduction in various aspects of sensing and adaptability. Miniaturized LC circuit was patterned by depositing by physical vapor deposition onto a ceramic substrate. Additionally, the size reduction will boost the capacitance of the circuit which will assist in the reduction of the signal-to-noise ratio, ease of signal processing and reduces the sophistication of electronics. The fabricated thin films were characterized by grazing incident XRD and SEM to compare the formation of grain boundaries, phases with the thick film composite. The electrical characterization was completed in a similar fashion to compare results with thick film composites.

High-Temperature SAW Resonator Sensors: Electrode Design Specifics.

Surface acoustic wave (SAW) sensors are steadily paving the way to wider application areas. Their main benefit consisting in the possibility of wireless interrogation with the radio frequency interrogation signal being the only energy source for the reradiated signal. This feature is getting more and more attractive with the growing demand in monitoring multiple industrial objects difficult to access by wired sensors in harsh environments. Among such wider applications, the possibility of making measurements of temperature, deformation, vibrations, and some other parameters at temperatures in the range of 300 °C-1000 °C look quite promising. This paper concentrates on specific features of the SAW resonator-based sensors operation at this temperature range. High-temperature influences the material choice and thus the properties of SAW resonators design peculiarities intended for use at high temperature. It is suggested that preferable designs should use synchronous resonators with relatively thick electrodes (10% of wavelength) based on Ir or Pt alloys while benefiting from the possibilities of specific designs that could reduce the negative impact of thick electrodes on the manufacturing in quantity. This solution benefits from lower resonance frequency scatter because of the automatic compensation of SAW velocity decrease due to electrode metallization ratio increase. This compensation originates from the resonance frequency increase that is related to the decrease of the Bragg bandwidth defined by the reflection. It is shown in modeling examples that the value of metallization ratio at which this compensation occurs is close to 65%-70%.

Erratum to “a passive wireless microelectromechanical pressure sensor for harsh environments” [feb 18 73-85

In the above paper [1] , references [46] and [54] were cited incorrectly. The corrected references are as follows.