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9 pages, 4085 KiB

Open AccessArticle

Temperature Dependence of the Dynamic Parameters of Contact Thermometers

by Silke Augustin and Thomas Fröhlich

Sensors 2019, 19(10), 2299; https://doi.org/10.3390/s19102299 - 18 May 2019

Cited by 4 | Viewed by 4428

Abstract

Contact thermometers are used in a wide temperature range as well as under various media and environmental conditions. The temperature can range from −200 °C to about 1500 °C. In this case, the dynamic parameters (time percentage values t_x and time constants [...] Read more.

Contact thermometers are used in a wide temperature range as well as under various media and environmental conditions. The temperature can range from −200 °C to about 1500 °C. In this case, the dynamic parameters (time percentage values t_x and time constants τ) depend on temperature. Several effects are superimposed. Constructional and material properties of the thermometer and the installation location affect the dynamic behavior as well as the type and material properties of the object to be measured. Thermal conductivity λ, specific heat capacity c, and density ρ depend on temperature. This temperature dependence can be mutually compensated for (see Section 3). At the same time, the dynamic behavior is also influenced by the temperature-dependent parameters of the medium. When the thermometers are installed in air, for example, the heat transfer coefficient α decreases with increasing temperature, owing to the temperature-dependent material data of the air, at constant speed v. At the same time, heat radiation effects are so strong that the heat transfer improves despite the decreasing convective heat transfer coefficient. In this paper, a number of examples are used to establish a model for the temperature dependence of the dynamic parameters for various thermometer designs. Both numerically and experimentally determined results for the determination of the dynamic characteristic values are included in the consideration. Full article

(This article belongs to the Special Issue Temperature Sensors)

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14 pages, 3886 KiB

Open AccessArticle

Strain-Independent Temperature Measurements with Surface-Glued Polarization-Maintaining Fiber Bragg Grating Sensor Elements

by Barbara Hopf, Bennet Fischer, Thomas Bosselmann, Alexander W. Koch and Johannes Roths

Sensors 2019, 19(1), 144; https://doi.org/10.3390/s19010144 - 3 Jan 2019

Cited by 11 | Viewed by 5013

Abstract

A novel technique for strain and temperature decoupling with surface-glued fiber Bragg gratings (FBGs) is presented and applied for strain-independent temperature measurements in a temperature range between −30 °C and 110 °C with uncertainties below 4 °C over the entire measurement range. The [...] Read more.

A novel technique for strain and temperature decoupling with surface-glued fiber Bragg gratings (FBGs) is presented and applied for strain-independent temperature measurements in a temperature range between −30 °C and 110 °C with uncertainties below 4 °C over the entire measurement range. The influence of temperature-dependent glue-induced transversal forces on the fiber sensor could be eliminated with a sensor element consisting of two FBGs in identical polarization-maintaining fibers that were spliced perpendicular to each other. After aligning and gluing the sensor element with its optical axes parallel and perpendicular to the specimen, the averaged Bragg wavelength shifts of both FBGs were proven to be independent of the glue’s influence and therefore independent of any change in the material characteristics of the glue, such as aging or creeping behavior. For the first time, this methodology enables temperature measurements with surface-attached bare FBGs independently of arbitrary longitudinal and glue-induced strains. This is of great value for all applications that rely on a fully glued sensor design, e.g., in applications with high electromagnetic fields, on rotating parts, or in vacuum for space applications. Full article

(This article belongs to the Special Issue Temperature Sensors)

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12 pages, 2375 KiB

Open AccessArticle

Development of Body-Tissue Temperature-Control Transducer

by Audrone Dumciene and Saule Sipaviciene

Sensors 2019, 19(1), 14; https://doi.org/10.3390/s19010014 - 20 Dec 2018

Cited by 4 | Viewed by 4604

Abstract

The aim of this study was to develop a transducer for non-invasive temperature measurement in deeper tissue layers during tissue cooling. Simulation of the temperature field distribution in human tissues and the transducer were done, and the influence of transducer structure and material [...] Read more.

The aim of this study was to develop a transducer for non-invasive temperature measurement in deeper tissue layers during tissue cooling. Simulation of the temperature field distribution in human tissues and the transducer were done, and the influence of transducer structure and material properties were studied. Using simulation results, the experimental transducer was designed for temperature measurement in deeper tissue layers during cooling. The temperature measurements with the needle thermometer and the transducer were well correlated at both before tissue cooling r = 0.723 and after cooling r = 0.945, and the temperature difference was no more than ±0.2 °C. Full article

(This article belongs to the Special Issue Temperature Sensors)

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13 pages, 5476 KiB

Open AccessArticle

Temperature Measurement of Fluid Flows by Using a Focusing Schlieren Method

by A. Martínez-González, D. Moreno-Hernández, J. A. Guerrero-Viramontes, M. León-Rodríguez, J. C. I. Zamarripa-Ramírez and C. Carrillo-Delgado

Sensors 2019, 19(1), 12; https://doi.org/10.3390/s19010012 - 20 Dec 2018

Cited by 20 | Viewed by 6019

Abstract

A method for measuring planar temperature fields of fluid flows is proposed. The focusing schlieren technique together with a calibration procedure to fulfill such a purpose is used. The focusing schlieren technique uses an off-axis circular illumination to reduce the depth of focus [...] Read more.

A method for measuring planar temperature fields of fluid flows is proposed. The focusing schlieren technique together with a calibration procedure to fulfill such a purpose is used. The focusing schlieren technique uses an off-axis circular illumination to reduce the depth of focus of the optical system. The calibration procedure is based on the relation of the intensity level of each pixel of a focused schlieren image to the corresponding cutoff grid position measured at the exit focal plane of the schlieren lens. The method is applied to measure planar temperature fields of the hot air issuing from a 10 mm diameter nozzle of a commercial Hot Air Gun Soldering Station Welding. Our tests are carried out at different temperature values and different planes along the radial position of the nozzle of the hot air. The experimental values of temperature measurements are in agree with those measured using a thermocouple. Full article

(This article belongs to the Special Issue Temperature Sensors)

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10 pages, 1891 KiB

Open AccessArticle

On the Influence of Infra-Red Sensor in the Accurate Estimation of Grinding Temperatures

by Lander Urgoiti, David Barrenetxea, Jose Antonio Sánchez, Iñigo Pombo and Jorge Álvarez

Sensors 2018, 18(12), 4134; https://doi.org/10.3390/s18124134 - 26 Nov 2018

Cited by 12 | Viewed by 3359

Abstract

Workpiece rejection originated by thermal damage is of great concern in high added-value industries, such as automotive or aerospace. Surface temperature control is vital to avoid this kind of damage. Difficulties in empirical measurement of surface temperatures in-process imply the measurement in points [...] Read more.

Workpiece rejection originated by thermal damage is of great concern in high added-value industries, such as automotive or aerospace. Surface temperature control is vital to avoid this kind of damage. Difficulties in empirical measurement of surface temperatures in-process imply the measurement in points other than the ground surface. Indirect estimation of temperatures demands the use of thermal models. Among the numerous temperature measuring techniques, infra-red measurement devices excel for their speed and accurate measurements. With all of this in mind, the current work presents a novel temperature estimation system, capable of accurate measurements below the surface as well as correct interpretation and estimation of temperatures. The estimation system was validated by using a series of tests in different grinding conditions that confirm the hypotheses of the error made when measuring temperatures in the workpiece below the surface in grinding. This method provides a flexible and precise way of estimating surface temperatures in grinding processes and has shown to reduce measurement error by up to 60%. Full article

(This article belongs to the Special Issue Temperature Sensors)

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15 pages, 3338 KiB

Open AccessArticle

Application of Additive Layer Manufacturing Technique on the Development of High Sensitive Fiber Bragg Grating Temperature Sensors

by Arnaldo Leal-Junior, Jonathan Casas, Carlos Marques, Maria José Pontes and Anselmo Frizera

Sensors 2018, 18(12), 4120; https://doi.org/10.3390/s18124120 - 24 Nov 2018

Cited by 72 | Viewed by 4902

Abstract

This paper presents the development of temperature sensors based on fiber Bragg gratings (FBGs) embedded in 3D-printed structures made of different materials, namely polylatic acid (PLA) and thermoplastic polyurethane (TPU). A numerical analysis of the material behavior and its interaction with the FBG [...] Read more.

This paper presents the development of temperature sensors based on fiber Bragg gratings (FBGs) embedded in 3D-printed structures made of different materials, namely polylatic acid (PLA) and thermoplastic polyurethane (TPU). A numerical analysis of the material behavior and its interaction with the FBG sensor was performed through the finite element method. A simple, fast and prone to automation process is presented for the FBG embedment in both PLA and TPU structures. The temperature tests were made using both PLA- and TPU-embedded FBGs as well as an unembedded FBG as reference. Results show an outstanding temperature sensitivity of 139 pm/°C for the FBG-embedded PLA structure, which is one of the highest temperature sensitivities reported for FBG-based temperature sensors in silica fibers. The sensor also shows almost negligible hysteresis (highest hysteresis below 0.5%). In addition, both PLA- and TPU-embedded structures present high linearity and response time below 2 s. The results presented in this work not only demonstrate the feasibility of developing fully embedded temperature sensors with high resolution and in compliance with soft robot application requirements, but also show that the FBG embedment in such structures is capable of enhancing the sensor performance. Full article

(This article belongs to the Special Issue Temperature Sensors)

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12 pages, 9902 KiB

Open AccessArticle

Enhanced Accuracy of CMOS Smart Temperature Sensors by Nonlinear Curvature Correction

by Gareth D. Lewis, Patrick Merken and Marijke Vandewal

Sensors 2018, 18(12), 4087; https://doi.org/10.3390/s18124087 - 22 Nov 2018

Cited by 16 | Viewed by 5491

Abstract

In this paper, we demonstrate an improvement in the accuracy of a low-cost smart temperature sensor, by measurement of the nonlinear curvature correction at multiple temperature references. The sensors were positioned inside a climate chamber and connected outside to a micro-controller via a [...] Read more.

In this paper, we demonstrate an improvement in the accuracy of a low-cost smart temperature sensor, by measurement of the nonlinear curvature correction at multiple temperature references. The sensors were positioned inside a climate chamber and connected outside to a micro-controller via a network cable. The chamber temperature was increased systematically over a wide range from −20

^{°}

C to 55

^{°}

C. A set of calibration curves was produced from the best fitting second-order polynomial curves for the offset in temperature between the sensor and reference. An improvement in accuracy of ±0.15

^{°}

C is with respect to the mentioned temperature range, compared to the significantly higher value reported of ±0.5

^{°}

C by the manufacturer for similar conditions. In summary, we demonstrate a significant improvement in the calibration of a low-cost, smart sensor frequently used in research and academic projects over a useful range of temperatures. Full article

(This article belongs to the Special Issue Temperature Sensors)

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14 pages, 2603 KiB

Open AccessArticle

Fabrication and Thermoelectric Characterization of Transition Metal Silicide-Based Composite Thermocouples

by Gunes A. Yakaboylu, Rajalekshmi C. Pillai, Katarzyna Sabolsky and Edward M. Sabolsky

Sensors 2018, 18(11), 3759; https://doi.org/10.3390/s18113759 - 3 Nov 2018

Cited by 7 | Viewed by 4184

Abstract

Metal silicide-based thermocouples were fabricated by screen printing thick films of the powder compositions onto alumina tapes followed by lamination and sintering processes. The legs of the embedded thermocouples were composed of composite compositions consisting of MoSi₂, WSi₂, ZrSi [...] Read more.

Metal silicide-based thermocouples were fabricated by screen printing thick films of the powder compositions onto alumina tapes followed by lamination and sintering processes. The legs of the embedded thermocouples were composed of composite compositions consisting of MoSi₂, WSi₂, ZrSi₂, or TaSi₂ with an additional 10 vol % Al₂O₃ to form a silicide–oxide composite. The structural and high-temperature thermoelectric properties of the composite thermocouples were examined using X-ray diffraction, scanning electron microscopy and a typical hot–cold junction measurement technique. MoSi₂-Al₂O₃ and WSi₂-Al₂O₃ composites exhibited higher intrinsic Seebeck coefficients (22.2–30.0 µV/K) at high-temperature gradients, which were calculated from the thermoelectric data of composite//Pt thermocouples. The composite thermocouples generated a thermoelectric voltage up to 16.0 mV at high-temperature gradients. The MoSi₂-Al₂O₃//TaSi₂-Al₂O₃ thermocouple displayed a better performance at high temperatures. The Seebeck coefficients of composite thermocouples were found to range between 20.9 and 73.0 µV/K at a temperature gradient of 1000 °C. There was a significant difference between the calculated and measured Seebeck coefficients of these thermocouples, which indicated the significant influence of secondary silicide phases (e.g., Mo₅Si₃, Ta₅Si₃) and possible local compositional changes on the overall thermoelectric response. The thermoelectric performance, high sensitivity, and cost efficiency of metal silicide–alumina ceramic composite thermocouples showed promise for high-temperature and harsh-environment sensing applications. Full article

(This article belongs to the Special Issue Temperature Sensors)

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9 pages, 1640 KiB

Open AccessArticle

High-Resolution Temperature Sensor Based on Single-Frequency Ring Fiber Laser via Optical Heterodyne Spectroscopy Technology

by Liangcheng Duan, Haiwei Zhang, Wei Shi, Xianchao Yang, Ying Lu and Jianquan Yao

Sensors 2018, 18(10), 3245; https://doi.org/10.3390/s18103245 - 27 Sep 2018

Cited by 26 | Viewed by 4729

Abstract

We demonstrate a high-resolution temperature sensor based on optical heterodyne spectroscopy technology by virtue of the narrow linewidth characteristic of a single-frequency fiber laser. When the single-frequency ring fiber laser has a Lorentzian-linewidth <1 kHz and the temperature sensor operates in the range [...] Read more.

We demonstrate a high-resolution temperature sensor based on optical heterodyne spectroscopy technology by virtue of the narrow linewidth characteristic of a single-frequency fiber laser. When the single-frequency ring fiber laser has a Lorentzian-linewidth <1 kHz and the temperature sensor operates in the range of 3−85 °C, an average sensitivity of 14.74 pm/°C is obtained by an optical spectrum analyzer. Furthermore, a resolution as high as ~5 × 10⁻³ °C is demonstrated through optical heterodyne spectroscopy technology by an electrical spectrum analyzer in the range of 18.26–18.71 °C with the figure of merit up to 3.1 × 10⁵ in the experiment. Full article

(This article belongs to the Special Issue Temperature Sensors)

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17 pages, 10268 KiB

Open AccessArticle

Philosophy and Application of High-Resolution Temperature Sensors for Stratified Waters

by Hans Van Haren

Sensors 2018, 18(10), 3184; https://doi.org/10.3390/s18103184 - 20 Sep 2018

Cited by 26 | Viewed by 4367

Abstract

Every application may have its specifically designed sensor. For studying the effects of short-term temperature variations on life in water, a high-resolution sensor has been designed with low noise level <0.1 mK. Pro and cons of the design include its adequacy for use [...] Read more.

Every application may have its specifically designed sensor. For studying the effects of short-term temperature variations on life in water, a high-resolution sensor has been designed with low noise level <0.1 mK. Pro and cons of the design include its adequacy for use in large heat-capacity environments like water but less in air. The sensor can be used under high static environmental pressure of >1000 Bar (>10⁸ N m⁻²) in the deepest ocean regions. Its response time of 0.5 s in water allows quantitative studies of internal wave turbulent mixing effects, e.g., on the redistribution of matter and on nearly completely submerged human bodies. In a chain of >100 sensors, clocks are synchronized to sample within 0.02 s and a verified range of 600 m. Full article

(This article belongs to the Special Issue Temperature Sensors)

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10 pages, 3249 KiB

Open AccessArticle

Developing Efficient Thin Film Temperature Sensors Utilizing Layered Carbon Nanotube Films

by Shrutidhara Sarma and Jang Ho Lee

Sensors 2018, 18(10), 3182; https://doi.org/10.3390/s18103182 - 20 Sep 2018

Cited by 23 | Viewed by 4557

Abstract

In this paper, we present the fabrication of an efficient thin film temperature sensor utilizing chemical vapor deposited carbon nanotube (CNT) film as the sensing element on Si substrates, with diamond-like carbon (DLC):Ni as a catalyst in assisting CNT growth. The fabricated sensor [...] Read more.

In this paper, we present the fabrication of an efficient thin film temperature sensor utilizing chemical vapor deposited carbon nanotube (CNT) film as the sensing element on Si substrates, with diamond-like carbon (DLC):Ni as a catalyst in assisting CNT growth. The fabricated sensor showed good electrical response with change in temperature. Relative linear change in resistance of 18.4% for an increase in temperature from 22 °C to 200 °C was achieved. Various characterizing techniques, such as scanning electron microscopy (SEM) and Raman spectroscopy, were used to characterize the films. In an effort to study device performance, van der Pauw and Hall measurements were carried out to study the dependence of resistance on temperature and magnetic fields. Temperature coefficient of resistance of the sensor was calculated as 1.03 × 10⁻³/°C. All implications arising from the study are presented. The results establish the aptness of the as-grown CNT film to be used as an active sensing material in thin film temperature sensors. Full article

(This article belongs to the Special Issue Temperature Sensors)

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14 pages, 4014 KiB

Open AccessArticle

Electrical and Thermal Properties of Heater-Sensor Microsystems Patterned in TCO Films for Wide-Range Temperature Applications from 15 K to 350 K

by Ryszard Pawlak and Marcin Lebioda

Sensors 2018, 18(6), 1831; https://doi.org/10.3390/s18061831 - 5 Jun 2018

Cited by 11 | Viewed by 5878

Abstract

This paper presents an analysis of the electrical and thermal properties of miniature transparent heaters for use in a wide range of temperature applications, from 15 K to 350 K. The heater structures were produced in transparent conducting oxide (TCO) layers: indium tin [...] Read more.

This paper presents an analysis of the electrical and thermal properties of miniature transparent heaters for use in a wide range of temperature applications, from 15 K to 350 K. The heater structures were produced in transparent conducting oxide (TCO) layers: indium tin oxide (ITO) and ITO/Ag/ITO on polymer substrates-polyethylene naphthalate (PEN) and polyethylene terephthalate (PET), by direct laser patterning. Thermo-resistors for temperature measurement were created in the same process, with geometry corresponding to the shape of the heating path. The thermo-resistors integrated with the heating structure allowed easy control of the thermal state of the heaters. Laser patterning provided high precision and repeatability in terms of the geometry and electrical properties of the heater-sensor structures. Measurements at temperatures from 15 K to above room temperature (350 K) confirmed the excellent dynamics of the heating and cooling processes, due to current flow. The largest value for surface heating power was over 3 W/cm². A heater-sensor structure equipped with a small capacity chamber was successfully applied for controlled heating of small volumes of different liquids. Such structures have potential for use in research and measurements, where for various reasons controlled and accurate heating of small volumes of liquids is required. Full article

(This article belongs to the Special Issue Temperature Sensors)

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10 pages, 3763 KiB

Open AccessArticle

A Flexible Temperature Sensor Based on Reduced Graphene Oxide for Robot Skin Used in Internet of Things

by Guanyu Liu, Qiulin Tan, Hairong Kou, Lei Zhang, Jinqi Wang, Wen Lv, Helei Dong and Jijun Xiong

Sensors 2018, 18(5), 1400; https://doi.org/10.3390/s18051400 - 2 May 2018

Cited by 205 | Viewed by 13465

Abstract

Flexible electronics, which can be distributed on any surface we need, are highly demanded in the development of Internet of Things (IoT), robot technology and electronic skins. Temperature is a fundamental physical parameter, and it is an important indicator in many applications. Therefore, [...] Read more.

Flexible electronics, which can be distributed on any surface we need, are highly demanded in the development of Internet of Things (IoT), robot technology and electronic skins. Temperature is a fundamental physical parameter, and it is an important indicator in many applications. Therefore, a flexible temperature sensor is required. Here, we report a simple method to fabricate three lightweight, low-cost and flexible temperature sensors, whose sensitive materials are reduced graphene oxide (r-GO), single-walled carbon nanotubes (SWCNTs) and multi-wall carbon nanotubes (MWCNTs). By comparing linearity, sensitive and repeatability, we found that the r-GO temperature sensor had the most balanced performance. Furthermore, the r-GO temperature sensor showed good mechanical properties and it could be bent in different angles with negligible resistance change. In addition, the performance of the r-GO temperature sensor remained stable under different kinds of pressure and was unaffected by surrounding environments, like humidity or other gases, because of the insulating layer on its sensitive layer. The easy-fabricated process and economy, together with the remarkable performance of the r-GO temperature sensor, suggest that it is suitable for use as a robot skin or used in the environment of IoT. Full article

(This article belongs to the Special Issue Temperature Sensors)

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Review

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25 pages, 5865 KiB

Open AccessReview

Carbon Nanotubes and Carbon Nanotube Structures Used for Temperature Measurement

by Bogdan Florian Monea, Eusebiu Ilarian Ionete, Stefan Ionut Spiridon, Daniela Ion-Ebrasu and Emil Petre

Sensors 2019, 19(11), 2464; https://doi.org/10.3390/s19112464 - 29 May 2019

Cited by 46 | Viewed by 13026

Abstract

Accurate measurement of temperatures with low power consumption with the highest sensitivity and smallest possible elements is still a challenge. The thermal, electrical, and mechanical properties of carbon nanotubes (CNTs) have suggested that their use as a very sensitive sensing element will allow [...] Read more.

Accurate measurement of temperatures with low power consumption with the highest sensitivity and smallest possible elements is still a challenge. The thermal, electrical, and mechanical properties of carbon nanotubes (CNTs) have suggested that their use as a very sensitive sensing element will allow the creation of different sensors, far superior to other devices of similar size. In this paper, we present a short review of different constructive designs of CNTs based resistive sensors used for temperature measurement, available in literature, assembled using different processes, such as self-assembly, drop-casting from a solution, thin films obtained by gluing, printing, spraying, or filtration over a special membrane. As particular cases, temperature sensors obtained from CNT-polymer nanocomposite structures, CNTs filled with uniformly dispersed Fe₃O₄ nanoparticles or with gallium, and carbon nanotube wires (CNWs) hybrids are presented. Using these preparation procedures, mixtures of CNTs with different dimensions and chirality, as well as with a variable level of impurities and structural defects, can be produced. The sensors’ performance charts are presented, highlighting a number of aspects regarding the applicability of CNT structures for temperature measurement ranging from cryogenic temperatures to high temperatures, the limitations they have, their characteristics and advantages, as well as the special situations that may arise given the particular structure of these new types of materials, together with basic relationships and parameters for CNTs characterization. Further research will be required to develop the techniques of manipulating and depositing individual CNTs on supports and electrodes for the development of temperature sensors. Full article

(This article belongs to the Special Issue Temperature Sensors)

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11 pages, 1204 KiB

Open AccessReview

Plant Temperature Sensors

by Tomoaki Sakamoto and Seisuke Kimura

Sensors 2018, 18(12), 4365; https://doi.org/10.3390/s18124365 - 10 Dec 2018

Cited by 28 | Viewed by 8335

Abstract

Temperature is one of the most important environmental signals for plants. High and low temperatures have a variety of effects that affect plant growth and development profoundly. Further, temperature is an indication of seasonal change. Plants must survive under severe conditions in winter [...] Read more.

Temperature is one of the most important environmental signals for plants. High and low temperatures have a variety of effects that affect plant growth and development profoundly. Further, temperature is an indication of seasonal change. Plants must survive under severe conditions in winter and prepare to resume growth and reach their reproductive stage in the following spring. Recent studies have focused on plant mechanisms responsible for sensing temperature and the molecular systems underlying plant reactions in response to this signal. In this review, we describe how plants sense ambient temperature to adapt to ambient-temperature changes. Full article

(This article belongs to the Special Issue Temperature Sensors)

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