High Temperature Sensor Research Articles

Highly sensitive temperature and curvature sensor based on seven-core fiber

A high sensitivity temperature and curvature micro-fiber Mach-Zehnder interferometer (MMZI) sensor is proposed and demonstrated. A peanut structure is fused by a section of seven-core fiber (SCF) and a section of single-mode fiber (SMF). Then the SCF is connected to another SMF and tapered. Finally, the composite structure with the tapered SCF and the SCF-SMF peanut structure is fabricated. The coupling efficiency can be significantly improved, and more high-order modes can be stimulated via the new sensor structure. The experimental results demonstrated that the maximum temperature sensitivity is 836.67 pm/ °C in the range of 35 °C to 40 °C, which is the highest temperature sensitivity of the peanut-shaped MMZI sensor to the best of our knowledge. Furthermore, the sensor can be used for curvature measurement. When the curvature changes from 0 m−1 to 0.0522449 m−1, the sensitivity can achieve 93.33664 nm/m−1. The proposed sensor not only provides a novel method to fabricate a high-sensitivity sensor by combining different types of fibers, but it also has a meaningful application prospect in the fields of biological detection and environmental monitoring.

High Sensitivity SIW-CSRR Temperature Sensor Based on Microwave Scattering

High Sensitivity SIW-CSRR Temperature Sensor Based on Microwave Scattering

Indirect bonding of MgO wafers based on intercalation crystallisation of amorphous MgO film

Breakthroughs in high-temperature sensors require the achievement of a high bonding strength using a single wafer material to overcome thermal expansion mismatch. In this context, to improve the bonding strength of MgO (100)/MgO (100) wafers, an indirect bonding method based on inserting an amorphous MgO film at the interface is proposed herein. Notably, this method increased the bonding strength from 7 to 10.7 MPa without the introduction of other materials. Grazing incidence X-ray diffraction (GIXRD) and transmission electron microscopy (TEM) results showed that the films crystallised to MgO (100) under the thermocompression bonding parameters of vacuum, 1200 °C, and 4.3 MPa. In addition, the deposition temperature affected the bonding strength. Particularly, the film deposited at 200 °C exhibited the best improvement effect, while those deposited at other temperatures were suboptimal. This method avoids bonding failure caused by a sharp difference in thermal expansion between materials at high temperatures. Consequently, this method provides a key technology to improve the high-temperature resistance of MEMS devices using MgO wafer bonding.

Ultra-small high‐temperature pressure sensor chips fabricated in single‐layer (111) SOI wafers

This paper presents a 0.5 mm × 0.5 mm tiny-sized high-temperature piezoresistive pressure sensor fabricated with a thin-film under bulk single-sided micromachining process from the front-side of single-layer (111) silicon on insulator (SOI) wafer. The (111)-device layer of the SOI wafer is specifically selected to optimize the piezoresistor performance where the SiO2 buried layer isolates the piezoresistors from the handle substrate. And the (111)-handle layer is employed to subtly construct a single-crystalline-silicon beam-island combining with a very thin but uniform poly-silicon diaphragm for realization of both low nonlinearity and high sensitivity. Without double-sided micromachining process and wafer bonding used, a tiny sensor-chip size of 0.5 mm × 0.5 mm is achieved, which is required in wind-tunnel systems for measuring pressure distribution at high temperature. The testing results of the fabricated sensor show high sensitivity of 0.15 mV V−1 kPa−1 for 150 kPa measure range and satisfactory linearity of ±0.11% FS (full scale) at ambient temperature. At 350 °C, the overall accuracy is 0.17% FS and the thermal hysteresis is 0.22% FS. The temperature coefficient of zero-point offset of the sensor is tested as low as 0.01% °C−1 FS and the temperature coefficient of sensitivity is −0.07% °C−1 FS within the whole temperature range from −55 °C to 350 °C. Featuring the advantages of high accuracy and high-yield low-cost fabrication, the tiny-sized high-temperature pressure sensors exhibit promising perspectives in the field of aerospace industry including wind-tunnel applications.

A review of high-temperature solid-state ammonia sensors

A review of high-temperature solid-state ammonia sensors

Fabrication of 4H-SiC piezoresistive pressure sensor for high temperature using an integrated femtosecond laser-assisted plasma etching method

The processing, particularly, etching of brittle, hard, and anti-corrosion materials represented by the third-generation wide bandgap semiconductor silicon carbide (SiC), is a significant challenge. Although SiC has excellent electrical, mechanical, and chemical properties, the difficulty of processing limits its application in various sensor devices. To solve this problem, in this study, an integrated processing method of femtosecond laser-assisted SiC dry etching is proposed, which realizes high surface quality and high rate etching of the SiC microstructure. Specifically, the effects of different laser processing parameters on the processing effect were first studied through orthogonal experiments. Experiments indicate that compared with laser power and laser scan times, laser processing speed has a more obvious impact on the processing effect. Subsequently, considering the elastic modulus anisotropy of SiC, a 5 MPa piezoresistive pressure sensor chip was designed. Using the proposed composite processing method, a chip sensitive diaphragm was obtained. The diaphragm thickness and diameter are 76 μm and 1700 μm respectively. The overall sensor chip dimension was 4000 μm × 4000 μm × 350 μm. Static tests demonstrated that the sensor have excellent performance with sensitivity of 6.8 mV/MPa, linearity of 0.69% FS, and repeatability of 0.078% FS. In addition, by designing high-temperature packaging, the sensor achieved a pressure test at 400 °C. This study verifies the feasibility of the composite processing method, realizes the fabrication and measurement of high-temperature pressure sensors, and provides a reference for the micro-and nanostructure processing of various SiC sensors.

A micro graphene high temperature sensor with a single Si3N4 protective layer

Temperature sensors are widely used in industrial production, national defense and military fields. The traditional temperature sensors normally operate in a limited temperature range no more than 200 °C, which cannot be used for extreme high temperature detections. In this paper, a thermal protection method for the sensing graphene membrane is proposed and a graphene high temperature sensor has been fabricated and investigated. By growing a single silicon nitride (Si3N4) protective layer on top of graphene, our design not only solves the problem that graphene is easily oxidized at high temperature, but also prevents graphene from being polluted by impurities, which would lead to the degradation of graphene performance. We further explore the protective effect of Si3N4 layer with different thicknesses on the performance of the sensor. It has been found that the 400 nm Si3N4 protective layer gives the best protective capability. The sensor exhibits a positive temperature coefficient (PTC) from 50 to 600 °C and a maximal temperature coefficient of resistance (TCR) value of 0.29% °C−1 at 150 °C is achieved. It has been demonstrated that our graphene high temperature sensor with protective layer structure maintains good stability not only at high temperature up to 600 °C, but also over a long-period of time under room temperature. In short, the high temperature sensor possesses a wide temperature measurement range with micro dimensions, a relatively high TCR and a smaller thermal hysteresis. The thermal protection approach proposed in this paper provides a new idea for the fabrication of high temperature pressure sensor, which is expected to be applied in aerospace engines and oil wells, etc.

High sensitive temperature sensor based on narrow band-pass filters via optical heterodyne technique

High sensitive temperature sensor based on narrow band-pass filters via optical heterodyne technique

Structural, piezoelectric and ferroelectric analysis of 0.96Bi0.5Na0.5TiO3-0.06BaTiO3: xwt%MnO2 ceramics for high-tech applications

With the rapid growth to design and engineer the smart and efficient electronic devices like piezoelectric sensors, the surge for the materials with multifunctional properties have risen tremendously. Herein, a morphotropic phase boundary (MPB) existent 0.94(Bi0.5Na0.5TiO3)-0.06BaTiO3 (BNBT) ceramics have been fabricated and the influence of additive MnO2 (0–0.20 wt%) has been examined, via structural, morphological, ferroelectric and dielectric analysis. Keeping the MPB region stable, BNBT:0.15Mn ceramic has shown the much improved results with remnant polarization (Pr) of 38.72 μC/cm2, piezoelectric coefficient (d33) of 211 pC/N, and dielectric constant (ϵr) of 4502, sample has maintained its stable d33 value (198 pC/N) till 200 °C. Moreover, the dielectric constant dependence on temperature analysis has been observed to analyze the Curie temperature (TC) of the samples, where BNBT:0.15Mn ceramic has exhibited the TC of ∼335 °C, which is the main reason of achieving the stable piezoelectric effect till 200 °C. Present study not only provides the new direction for the material engineering but also demonstrates the potential of the reported material for high-temperature piezoelectric sensors.

Fabrication of SiC-Type Films Using Low-Energy Plasma-Enhanced Chemical Vapor Deposition (PECVD) and Subsequent Pyrolysis

Silicon carbide (SiC) is a promising material for a variety of applications in the biomedical, aerospace, and energy industries. Solution-phase techniques have long been used to deposit precursor films prior to pyrolysis into SiC, but they tend to face difficulties with substrate compatibility and the use of toxic solvents. In this study, we introduce a solventless synthesis route for fabricating SiC-type films by depositing an organosilicon copolymer poly(vinylphenyldimethylsilane-co-divinylbenzene) (p(VPDMS-co-DVB)) film using low-energy plasma chemical vapor deposition (PECVD) followed by subsequent pyrolysis. The chemical structure of the film was systematically studied in situ during pyrolysis as a function of temperature using diffuse reflection infrared Fourier transform spectroscopy (DRIFTS). The majority of the functional groups were found to have disappeared by a temperature of 800 °C, with most of the mass loss occurring between 350 and 520 °C. Thermogravimetric analysis (TGA) was used to measure the loss of mass as the pyrolysis temperature was increased, and the observed pyrolysis rates were compared to estimates of such rates from the DRIFTS analysis. Our proposed synthesis route provides a scalable and solventless method of producing SiC-type ceramic films for such applications as high-temperature sensors and membranes.

High-Tolerance Thin-Film Solder Joints for Electrical Interconnection in Harsh Environments

This paper presents a pioneering use of thin-film solder joint in the electrical interconnection of high-temperature thin-film sensors, which aims to improve the low tolerance of traditional soldered balls in extreme environments. The structure of the thin-film solder joint, composed of silver foil, solder joint paste, and metal wire, has a negligible mass compared to traditional soldered balls. As a result, the inertia force on the solder joint/substrate interface during vibration and force impact is greatly reduced, improving the reliability of the solder joint under thermal-mechanical coupling impacts. The thin-film solder joint has been verified using both metal (AgPd paste) and ceramic (TiB2/SiCNO paste) solders, and can withstand extreme environments such as thermal shock and high "g" loading. The designed thin-film solder joint can withstand impact energy of up to 3 J at 1000 °C without failure, which is 6 times higher than that of traditional soldered balls (with a statistical failure rate of up to 67% under 0.5 J impact). The thin-film solder joint was successfully used for electrical interconnection of high-temperature thin-film strain gauges, demonstrating excellent reliability under thermal-mechanical coupling impacts at 1000 °C. Our high-tolerance thin-film solder joints show promising potential for use in electrical interconnection in harsh environments.

Design, Preparation, and Performance Study of a Miniaturized High-Temperature Thick-Film Heat Flux Sensor

Solving heat transfer problems in high-temperature and temperature-changing environments is critical in a variety of applications, including modern turbines, aerospace, and nuclear power plants. However, most current thin-film-type heat flow sensors operate at approximately 1000 °C. Thus, we fabricated a kind of platinum–platinum/rhodium thick-film thermopile-type heat flux sensor which can work stably at 1200 °C based on an alumina ceramic substrate. The entire electrode layer was prepared by screen printing process. The surface morphology of the Pt electrode and the material in thermal resistance layer at different stages were investigated using scanning electron microscopy. The steady-state characteristics of the sensor were evaluated by using a high-temperature test platform. The experiments show that the peak voltage of the sensor is 1.4126 mV at the temperature of 1200 °C and the heat flow density of 283.3 kW/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . Moreover, the repeatability of sensor at 1200 °C and high temperature holding for 4 h experiments were performed, verifying that the sensor has good consistency and durability. Therefore, we infer that the designed sensor can be applied for a long time under high temperature and large heat flow conditions, such as aerospace, mechanical metallurgy and energy construction fields.

High Operational Temperature Sensors (DOD)

Federal Grants & ContractsVolume 47, Issue 13 p. 5-5 Grants Alerts High Operational Temperature Sensors (DOD) First published: 30 May 2023 https://doi.org/10.1002/fgc.33065Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article. Volume47, Issue131 June 2023Pages 5-5 RelatedInformation

Compact highly sensitive Fabry-Perot temperature and gas pressure sensing probe fabricated by a femtosecond laser and PDMS.

A high sensitivity optical fiber temperature and gas pressure sensor with integrated micro-cavity is proposed. First, a single-mode optical fiber (SMF) is spliced with a section of capillary, and then the sensitive material polydimethylsiloxane (PDMS) is filled into the capillary to form a Fabry-Perot interferometer (FPI). Finally, a femtosecond laser is used to ablate the fiber core of the SMF to form the third reflecting surface, constituting two cascaded FPIs. When two FPIs have a similar free spectral range, a Vernier effect is produced. The temperature and gas pressure sensitivity of the sensor reached 14.41 nm/°C and 113.82 nm/MPa, respectively, after using the sensitive material and Vernier effect double sensitization technology. In addition, a fiber Bragg grating is cascaded with the sensor, which can realize the simultaneous measurement of temperature and gas pressure and eliminate cross-sensitivity.

Sustainable Approach toward the Development of Next-Generation Gas Sensors

The increase in the usage of non-biodegradable substrates and the generation of toxic wastes from laboratories has led to a sharp increase in the pollution caused by the electronics industry. In this study, we report on a novel approach to tackle this by successfully fabricating a completely biodegradable and eco-friendly chemiresistive gas sensor. The substrate was made of bioplastic and was coated with a silk mesh. This substrate was thoroughly studied for its flexibility, tensile strength, biodegradability, and thermal stability. It was found that the bioplastic/silk substrate exhibited superior results as compared to the bioplastic substrate without silk. Further, a green synthesized CuO/ZnO heterostructure from clove extract was utilized as a receptor layer. It was observed that the device fabricated on a bioplastic/silk substrate outperforms the device with bioplastic substrates at room temperature, as well as at elevated temperature (i.e., 50 °C). The device exhibited an ideal piezotronics behavior demonstrating that the chemiresistive gas sensor with green synthesized CuO/ZnO heterostructures on a bioplastic/silk substrate can be very well used over curvilinear surfaces. Therefore, the sustainable approach toward the development of biodegradable and eco-friendly toxic gas sensors taken in this study can be an alternative to the current high-temperature sensors.

High-sensitivity interferometric high-temperature strain sensor based on optical harmonic vernier effect

We present a fiber optic vernier harmonic sensor for simultaneous detection of temperature and strain in high temperature conditions based on a parallel dual fiber Fabry-Perot interferometers (FPI). Two air-cavity FPIs were assembled from SMF, MMF and a hollow silica tube (HST). A fiber Bragg grating (FBG) is inscribed in one of the arms of the Fabry-Perot interferometers (FPIs) for temperature compensation. Based on the fiber optic vernier harmonic effect, the strain sensitivity of the sensor is further increased to 178.75 pm/µε, with a good linear response to strain and temperature in the range of 24 ℃-900 ℃. And the fabrication is straightforward and economy. It is a potential tool for micro strain measurements under extreme high temperature conditions.

Regenerated Fiber Bragg Gratings in Large Mode Area Fibers for High-Temperature Sensing

Regenerated fiber Bragg gratings (RFBGs) have been created in large mode area (LMA) fibers, and their key properties for their application as high-temperature sensors were experimentally characterized for the first time. UV written Type-I seed gratings in standard single-mode fibers (SMF-28) and in low numerical aperture LMA fibers with 125 μm and 250 μm cladding diameters were regenerated, and their wavelength drift characteristics at high temperatures, their temperature sensitivities, and their mechanical strengths were tested and compared with each other. We found that low dopant concentrations in the fiber cores led to lower wavelength drift rates during and after regeneration. A temperature calibration from room temperature to 800 °C showed that LMA fibers have generally similar but slightly lower temperature sensitivities than SMF-28 fibers. The tensile strength tests showed that LMA fibers with 250 μm cladding diameter have similar tensile fracture stresses as SMF-28 fibers but four times larger tensile force tolerances because of their twofold fiber diameter. Our research shows that using LMA fibers for RFBGs offers significant advantages for high-temperature sensing than their counterparts in standard fibers, which are also applicable to other silica fiber-based high-temperature sensors.

Oxygen doping modulating thermal-activated charge transport of reduced graphene oxide for high performance temperature sensors

Graphene and its derivatives have sparked intense research interest in wearable temperature sensing due to their excellent electric properties, mechanical flexibility, and good biocompatibility. Despite these advantages, the weak temperature dependence of charge transport makes them difficult to achieve a highly sensitive temperature response, which is one of the remaining bottlenecks in the progress towards practical applications. Unfortunately, detailed knowledge about the key factors of the charge transport temperature dependence in this material that determines the critical performance of electrical sensors is very limited up to now. Here, we reveal that oxygen absorption on the ultrathin reduced graphene oxide (RGO) films (∼3 nm) can significantly increase their conductance activation energy over 200% and thus greatly improve the temperature dependence of thermal-activated charge transport. Further investigations suggest that oxygen introduces the deep acceptor states, distributed at an energy level ∼0.175 eV from the valence-band maximum, which allows a highly temperature-dependent impurity ionization process and the resulting vast holes release in a wide temperature range. Remarkably, our temperature sensors based on oxygen-doped ultrathin RGO films show a high sensitivity with temperature conductive coefficient of 14.58% K−1, which is one order of magnitude higher than the reported CNT or graphene-based devices. Moreover, the ultrathin thickness and high thermal conductivity of RGO film allow an ultrafast response time of ∼86 ms, which represents the best level of temperature sensors based on soft materials. Profiting from these advantages, our sensors show good capacity to identify the slight temperature difference of human body, monitor respiratory rate, and detect the environmental temperature. This work not only represents substantial performance advances in temperature sensing, but also provides a new approach to modulate the charge transport temperature dependence, which could be benefited to both device design and fundamental research.

Design and Fabrication of a High-Temperature SOI Pressure Sensor with Optimized Crossbeam Membrane.

This paper presents a SOI piezoresistive pressure sensor with the crossbeam membrane. The roots of the crossbeam were widened, which solved the problem of the poor dynamic performance of small-range pressure sensors working at a high temperature of 200 °C. A theoretical model was established to optimize the proposed structure, which combined the finite element and the curve fitting. Using the theoretical model, the structural dimensions were optimized to obtain the optimal sensitivity. During optimization, the sensor nonlinearity was also taken into consideration. The sensor chip was fabricated by MEMS bulk-micromachining technology, and Ti/Pt/Au metal leads were prepared to improve the sensor ability of high-temperature resistance over a long time. The sensor chip was packaged and tested, and the experimental results show the sensor achieved an accuracy of 0.241% FS, nonlinearity of 0.180% FS, hysteresis of 0.086% FS and repeatability of 0.137% FS at the high temperature. Given the good reliability and performance at the high temperature, the proposed sensor provides a suitable alternative for the measurement of pressure at high temperatures.

Extensive Gaseous Emissions Reduction of Firewood-Fueled Low Power Fireplaces by a Gas Sensor Based Advanced Combustion Airflow Control System and Catalytic Post-Oxidation

In view of the tremendous emissions of toxic gases and particulate matter (PM) by low-power firewood-fueled fireplaces, there is an urgent need for effective measures to lower emissions to keep this renewable and economical source for private home heating available in the future. For this purpose, an advanced combustion air control system was developed and tested on a commercial fireplace (HKD7, Bunner GmbH, Eggenfelden, Germany), complemented with a commercial oxidation catalyst (EmTechEngineering GmbH, Leipzig, Germany) placed in the post-combustion zone. Combustion air stream control of the wood-log charge combustion was realized by five different control algorithms to describe all situations of combustion properly. These control algorithms are based on the signals of commercial sensors representing catalyst temperature (thermocouple), residual oxygen concentration (LSU 4.9, Bosch GmbH, Gerlingen, Germany) and CO/HC-content in the exhaust (LH-sensor, Lamtec Mess- und Regeltechnik für Feuerungen GmbH &amp; Co. KG, Walldorf (Germany)). The actual flows of the combustion air streams, as calculated for the primary and secondary combustion zone, are adjusted by motor-driven shutters and commercial air mass flow sensors (HFM7, Bosch GmbH, Gerlingen, Germany) in separate feedback control loops. For the first time, the residual CO/HC-content (CO, methane, formaldehyde, etc.) in the flue gas is in-situ monitored with a long-term stable AuPt/YSZ/Pt mixed potential high-temperature gas sensor, which allows continuous estimation of the flue gas quality with an accuracy of about ±10%. This parameter is not only an essential input for advanced combustion air stream control but also provides monitoring of the actual combustion quality and logging of this value over a whole heating period. By many firing experiments in the laboratory and by field tests over four months, it could be demonstrated that with this long-term stable and advanced automated firing system, depression of the gaseous emissions by about 90% related to manually operated fireplaces without catalyst could be achieved. In addition, preliminary investigations at a firing appliance complemented by an electrostatic precipitator yielded PM emission depression between 70% and 90%, depending on the firewood load.