Temperature Measurement Applications Research Articles

Application of Vaginal Temperature Measurement in Bitches

Finding innovative, non-invasive methods for continuously measuring body temperature minimizing human interference is important for accurate data collection. The objective of this study was to assess feasibility and accuracy of continuous body temperature measurements with loggers placed in the vaginal cavity of bitches. First, an in vitro experiment was performed to compare values obtained by temperature loggers (n = 26) to a calibrated liquid-in-glass thermometer. The mean differences between the two methods were low. Next, an in vivo experiment was performed using five healthy bitches, and values obtained by the vaginal loggers were compared to measurements collected rectally with digital thermometers. The results show that rectal and vaginal temperatures were correlated. The mean differences between rectal and vaginal temperatures were negligible. We conclude that the utilized temperature loggers provide accurate and reliable data.

In-Line Fiber Optic Interferometric Sensors in Single-Mode Fibers

In-line fiber optic interferometers have attracted intensive attention for their potential sensing applications in refractive index, temperature, pressure and strain measurement, etc. Typical in-line fiber-optic interferometers are of two types: Fabry-Perot interferometers and core-cladding-mode interferometers. It's known that the in-line fiber optic interferometers based on single-mode fibers can exhibit compact structures, easy fabrication and low cost. In this paper, we review two kinds of typical in-line fiber optic interferometers formed in single-mode fibers fabricated with different post-processing techniques. Also, some recently reported specific technologies for fabricating such fiber optic interferometers are presented.

Color theory perception of steady wide band liquid crystal thermometry

A color theory perspective to steady wide-band thermochromic liquid crystals (TLCs) is presented towards application in surface temperature measurements. In this regard, TLC color response experiments are conducted on an ex situ calibration plate under various illuminant spectra, and for a broad range of camera angle and white balance configurations.The findings indicate that by color theory guided application of eligible background image subtraction technique, in conjunction with appropriate camera white balance selection, accurate, illuminant and viewing angle invariant hue-temperature relations can be established. This yields more practical, robust and generalized calibration methodologies. The importance of an adequate processing technique, along with its implications in color theory and consequences on hue-temperature relation is addressed in detail towards applicability in a broad spectrum of experimental arrangements.

First practical applications of eye temperature measurements for estimation of the time of death in casework. Report of three cases

This paper presents first three successive cases of death where at scene measurements of the internal eyeball temperature soon after death allowed to precisely estimate the times of deaths based on this data (33.1°C, 32.2°C and 29.5°C, respectively), which were later confirmed during the police investigation. Simultaneously the rectal temperatures in all three cases were measured and appeared to be between 36.3 and 36.8°C-reflecting a living individual's body temperature. Thanks to a significantly faster postmortem decrease of the eye temperature and a residual or nonexistent plateau effect affecting the eye, using the formula developed in previous comprehensive studies in pigs, the time of death in real cases could be estimated with good precision: 1 h 33 min, 2 h 24 min and 3 h 17 min since death respectively. The actual TOD established during investigation appeared to be: between 1 h 30 min and 1 h 50 min in case 1; 1 h 55 min in case 2 and between 2 h 55 min and 3 h 05 min in case 3. Such precise estimation, mainly due to the plateau effect lasting up to a few hours, could not have been done based only on rectal temperature, commonly measured in forensic practice.

Temperature dependent resistivity of platinum–carbon composite nanowires grown by focused ion beam on SiO2/Si substrate

Experimental studies of the temperature dependent resistivity of platinum nanowires grown on an oxidised silicon wafer by using focused ion beam (FIB) have been made. A series of 4-terminal resistivity measurements were carried out in the temperature range 50-300K on single nanowires of width and thickness ~100nm grown by decomposition of an organometallic precursor using Ga^+ ions of different accelerating voltages from 10keV to 30keV. Energy dispersive X-ray spectroscopy showed the nanowires to be composed of more than 60% by volume of carbon, the remainder being principally platinum and gallium. The exact composition depends on the accelerating voltage of the ions used. There is clear evidence from cross-sectional microscopy that the material is a composite consisting of a metallic phase present in the form of nanoscale clusters, randomly distributed in a matrix of carbon. Electrical measurements are consistent with this, showing a critical volume concentration for conduction, which is typical of electron transport in composites with percolating metal phase. Results show an unexpectedly high sensitivity of the temperature dependence of resistivity near the critical volume concentration, which has been explained to arise from thermal strain effects. The anomalous temperature/strain effects observed in this investigation might be exploited in temperature measurement and strain sensor applications.

Wireless SAW Temperature Sensor System for High-Speed High-Voltage Motors

This paper gives an overview on the system development of a wireless surface acoustic wave (SAW) temperature measurement application in high-speed high-voltage motors. The measurement location of interest is on the rotor in the vicinity of the copper squirrel cage. To fit the sensor in a 4 mm bore, a custom packaging with outer dimensions of 10.0 × 3.1 × 2.0 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> has been developed. For the purpose of interrogation a mechanically robust metal slot antenna has been designed to withstand rotation speeds up to 15 000 rpm. As the sensor interacts only during a very short time of a few 100 μs with the reader antenna a fast frequency modulated continuous wave (FMCW) reader was developed. The reader operates in the ISM band of 2.4 GHz and achieves a typical sweep time for data acquisition of 100 μs. The sensor system has been tested both in test bed and real engine conditions and performed stable read outs, although in the real engine signal behavior is disturbed by reflections and possibly electromagnetic field bursts caused by the power converter.

The application of temperature measurement of the eyes by digital infrared thermal imaging as a prognostic factor of methylprednisolone pulse therapy for Graves’ ophthalmopathy

Graves' ophthalmopathy (GO) involves autoimmune process resulting in proptosis, congestion, oedema and diplopia. Werner's NOSPECS classification and clinical activity score (CAS) of GO cannot objectively describe the inflammatory status. Digital infrared thermal imaging (DITI) detects local temperature and may reflect the degree of orbital inflammation. The aim of this study was to evaluate the clinical application of the eye temperature measured by DITI. Forty-six patients with GO receiving intravenously methylprednisolone pulse therapy (MPT) were included in this study. Local temperatures of the lateral orbit, upper eyelid, inner caruncle, medial conjunctiva, lateral conjunctiva, lower eyelid and cornea were measured with DITI before and after MPT. CAS, proptosis, eye movement (EOM) and diplopia were also recorded. Improvement of CAS was defined as at least one point decrease at either side of the eye, which was 0.5 score decrease as to the average of bilateral CAS. Local temperatures of the eyes decreased after MPT. The mean value of temperature (MT) of 12 points including the lateral orbit, upper eyelid, inner caruncle, medial conjunctiva, lateral conjunctiva and lower eyelid of both eyes before MPT was 32.65 degrees . The mean change of MT after MPT (DeltaT) was -0.22 degrees. DeltaT significantly negative-correlated with basal MT (correlation coefficient=-0.54, p=0.004). Higher baseline MT and CAS before MPT correlated with higher possibility of improvement of CAS after MPT (p=0.013 and 0.012, respectively). Baseline MT and CAS together correlated with improvement of CAS after MPT better than baseline CAS alone could do (area under the receiver operating characteristic curve: 82.81% and 66.63%, respectively). Basal temperature of the eyes measured by DITI was an objective indicator of inflammation of GO. Combining CAS and MT could better predict the outcome of MPT than CAS alone.

Common rectifier diodes in temperature measurement applications below 50 K

In this paper we studied the use of common electronic semiconductor diodes in temperature measurements at cryogenic atmosphere. The motivation for this is the high price of calibrated cryogenic temperature sensors since there are some applications, like quench detection, in which a cheaper and a less accurate sensor would suffice. We measured the forward voltage as a function of temperature, Vf(T), of several silicon rectifier diodes to determine the accuracy and interchangeability of the diodes. The experimental results confimed that Vf(T) of common rectifier diodes are similar to cryogenic sensor diodes, but the variability between two samples is much larger. The interchangeability of the diodes proved to be poor if absolute temperatures are to be measured. However for sensing changes in temperature they proved to be adequate and thus can be used to measure e.g. quench propagation or sense quench ignition at multiple locations with cheap price.

Sol–gel deposition of multiply doped thermographic phosphor coatings Al 2O 3:(Cr 3+, M 3+) (M = Dy, Tm) for wide range surface temperature measurement application

A promising method of measuring surface temperatures in harsh environments is the use of thermographic phosphor coatings. There, the surface temperature is evaluated from the phosphorescence decay lifetime following a pulsed laser or flash lamp light excitation. Depending on the used dopant, single doped M 3+:α-Al 2O 3 (M = Cr, Dy, Tm) emit at 694 nm (Cr 3+), 488 nm (Dy 3+), 584 nm (Dy 3+), and 459 nm (Tm 3+), respectively. However, the accessible temperature range with a single dopant is limited: for the Cr 3+-transition from 293 K up to 900 K, and for the Dy 3+ and Tm 3+-transitions both from 1073 K up to 1473 K. In the present study a new approach is followed to extend these limitations by co-doping two dopants using the sol–gel method and dip coating of α-Al 2O 3 thin films. For that application (Dy 3+ + Cr 3+) co-doped thin α-Al 2O 3 films and (Tm 3+ + Cr 3+) co-doped α-Al 2O 3 films with thicknesses of 4–6 μm were prepared, and the temperature-dependent luminescence properties (emission spectra and lifetimes) were analysed after pulsed laser excitation in the UV (355 nm). The phosphorescence lifetime as a function of temperature were measured between 293 K and 1473 K. A considerably extended range for surface temperature evaluation was established following this new approach by combining different dopants on the molecular level.

Traceable radiometric calibration of semiconductor detectors and their application for thermodynamic temperature measurement

The non-contact measurement of temperature by using the emitted thermal radiation has been an innovative field of measurement science and fundamental physics for more than a hundred years. It saw the first highlight in Gustav Kirchhoff’s principle of a blackbody with ideal emission characteristics and culminated in Max Planck’s formulation of the law of thermal radiation, the so-called Planck’s law, forming the foundation of quantum physics. A boost in accuracy was the development of semiconductor detectors and the cryogenic electrical substitution radiometer in the late 1970s. Semiconductor detectors, namely photodiodes, deliver an electrical current proportional to the absorbed optical radiation. Due to the measurements of thermal radiation over a wide range of temperature and wavelength, thermodynamic temperature measurements with radiometric methods have set benchmarks to all, the electrical, dimensional and optical metrology. The paper describes the measurement of the spectral responsivity of semiconductor detectors traceable to the SI units and their application for thermodynamic temperature measurement by the absolute measurement of thermal radiation using filter radiometers with calibrated spectral irradiance responsivity.

Sol–gel deposition of multiply doped thermographic phosphor coatings Al 2O 3:(Cr 3+, M 3+) (M = Dy, Tm) for wide range surface temperature measurement application

A promising method of measuring surface temperatures in harsh environments is the use of thermographic phosphor coatings. There, the surface temperature is evaluated from the phosphorescence decay lifetime following a pulsed laser or flash lamp light excitation. Depending on the used dopant, single doped M 3+:α-Al 2O 3 (M = Cr, Dy, Tm) emit at 694 nm (Cr 3+), 488 nm (Dy 3+), 584 nm (Dy 3+), and 459 nm (Tm 3+), respectively. However, the accessible temperature range with a single dopant is limited: for the Cr 3+-transition from 293 K up to 900 K, and for the Dy 3+ and Tm 3+-transitions both from 1073 K up to 1473 K. In the present study a new approach is followed to extend these limitations by co-doping two dopants using the sol–gel method and dip coating of α-Al 2O 3 thin films. For that application (Dy 3+ + Cr 3+) co-doped thin α-Al 2O 3 films and (Tm 3+ + Cr 3+) co-doped α-Al 2O 3 films with thicknesses of 4–6 μm were prepared, and the temperature-dependent luminescence properties (emission spectra and lifetimes) were analysed after pulsed laser excitation in the UV (355 nm). The phosphorescence lifetime as a function of temperature were measured between 293 K and 1473 K. A considerably extended range for surface temperature evaluation was established following this new approach by combining different dopants on the molecular level.

Temperature imaging of sub-millimeter-thick water using a near-infrared camera

This paper presents a method of imaging temperature distributions of sub-millimeter-thick water using a near-infrared camera and optical narrow-bandpass filter. The principle is based on the temperature dependence of the ν1+ν3 absorption band of water. Temperature images are constructed by measuring the absorbance of water at the wavelength of 1412nm through the filter for all pixels of the camera. From calibration measurements on 0.5-mm thick water at temperatures from 26.0°C to 40.0°C, the temperature coefficient was 6.3×10−4K−1 and the standard deviation of absorbance was 1.9×10−4. Thermal diffusion in 0.5-mm thick water caused by a thin heating wire was visualized with this method. The obtained images were verified against temperature distributions calculated by solving a two-dimensional thermal conduction model. This method would be useful for temperature measurement applications and control of aqueous solutions in microchips.

Linearization Circuit of the Thermistor Connection

Thermistors have found wide application in temperature measurement and control in different fields, but they exhibit a strong nonlinearity of the characteristic, which is of an exponential type. This paper investigates the possibility of creating a thermistor-based temperature sensor with frequency and analog outputs and a linearized characteristic on the basis of a 7555 timer. It is shown through simulations that the linearization of the characteristic can be achieved without connecting additional elements to the circuit but only through a choice of the parameters of the thermistor and of the frequency-determining circuit elements. The investigations conducted show a good match between the theoretically and experimentally obtained characteristics. The proposed circuit is characterized by nonlinearity of plusmn1% in a specific temperature range, as well as high temperature stability.

Study of spectral and annealing properties of fiber Bragg gratings written in H_2-free and H_2- loaded fibers by use of femtosecond laser pulses

The spectral and annealing properties of a series of fiber Bragg gratings (FBGs) written in both H(2)-loaded and H(2)-free fibers by use of 800nm femtosecond laser pulse irradiation and created through a phase mask, have been investigated. It is found that type II FBGs inscribed in H(2)- loaded fibers exhibit superior spectral quality when compared with those written in H(2)-free fibers. Isochronal annealing tests shows that type II FBGs written in H(2)-free fibers have the highest thermal stability, followed (in order of stability) by H(2)-loaded type II, H(2)-free type I and then H(2)-loaded type I FBGs. The thermal stability of the H(2)-loaded type II FBGs can effectively be increased by using a high temperature pre-annealing treatment. After the treatment, type II FBGs written into both H(2)-free and H(2)-loaded fibers can sustain long-term annealing (for more than 12 hours) at temperatures of more than 1000 masculineC while their high reflectivities can still be maintained. This demonstrates the real potential of the FBGs developed and investigated in this work to be used as the ideal sensing elements for a series of high temperature measurement applications.

Precise Sound Velocity Measurement Using Laser Ultrasound and its Application for Temperature Measurement in Semiconductor Processing

Precise Sound Velocity Measurement Using Laser Ultrasound and its Application for Temperature Measurement in Semiconductor Processing

Multiplexed Fiber Fabry–Pérot Interferometer Sensors Based on Ultrashort Bragg Gratings

This letter reports a fiber Fabry-Peacuterot interferometer sensor formed by two closely spaced ultrashort uniform Bragg gratings within fiber core. The sensor has insertion loss as low as 0.002 dB which enables a considerable increase in the sensor's multiplexing capability. Fifty sensors are experimentally multiplexed along a single fiber using a frequency-division-multiplexing method. The potential of multiplexing more than 500 sensors is theoretically expected. The sensor's application in temperature and strain measurement is also investigated

Applications of fibre optic temperature measurement

Applications of fibre optic temperature measurement

Optical high temperature sensor based on green up-conversion emissions in Er 3+ doped Al 2O 3

Er 3+ doped Al 2O 3 has been prepared by a non-aqueous sol–gel method using aluminum isopropoxide as precursor, acetylacetone as chelating agent, nitric acid as catalyzer, and hydrated erbium nitrate as a dopant in an isopropanol environment. The fluorescence intensity ratio (FIR) of the green up-conversion emissions at the wavelengths of about 523 and 545 nm in the Er 3+ doped Al 2O 3 was studied as a function of temperature over a wide temperature range of 295–773 K, using a 978 nm semiconductor laser diode (LD) as an excitation source. The maximum sensitivity and the temperature resolution derived form the FIR of the green up-conversion emissions are approximately 0.0052 K −1 and 0.3 K, respectively. It is demonstrated that the prototype optical high temperature sensor based on the FIR technique from the green up-conversion emissions in the Er 3+ doped Al 2O 3 is promising for applications in high temperature measurement.

The Effects of Film Thickness, Light Polarization, and Light Intensity on the Light Transmission Characteristics of Thermochromic Liquid Crystals

Thermochromic liquid crystal materials change their crystalline structure and optical properties with temperature, making them useful in temperature measurement applications. This paper presents the results of a study to develop a temperature measurement system that uses light transmission through thermochromic liquid crystals instead of light reflection. We painted Hallcrest R25C10W sprayable liquid crystals on a clear surface and placed it in a spectrophotometer. The amount of light transmitted at monochromatic wavelengths from 400nm to 700nm was measured for temperatures from 25°C to 55°C under conditions of nonpolarized, linearly polarized, and cross-polarized light, for three light intensity levels, and three liquid crystal layer thicknesses. As the temperature was increased the amount of light transmitted through the liquid crystal layer increased. When the liquid crystals are in their active range the transmission spectra exhibit an s-curve shape and the percent of light transmitted through the liquid crystals at a fixed temperature increases with increasing wavelength. We detected significant changes in the transmission spectra for temperatures from 27°C to 48°C, whereas when used with reflected light the thermochromic liquid crystals are useful over a significantly smaller range. As the thickness of the thermochromic liquid crystal layer increases or as the incoming light intensity decreases, the amount of light transmitted through the liquid crystals decreases. We also investigated the effects of temperature overheat on the transmission spectra and found that heating the thermochromic liquid crystals above their active range increases the amount of light transmission. However, when the liquid crystals are cooled below their active range they return to their original state. We have analyzed the spectrophotometer data in a number of ways including: (a) total amount of light transmitted, (b) amount of red, green, and blue light transmitted; and (c) spectral curve shape characteristics (peak transmission, inflection wavelength and wavelength for peak transmission) all as a function of temperature. A linear relationship exists between temperature and all of these variables which we believe can be exploited for the development of a charge coupled light camera based light transmission system for temperature measurement.

Non-linear temperature dependence of Bragg gratings written in different fibres, optimised for sensor applications over a wide range of temperatures

Temperature measurements have been made by using fibre Bragg gratings (FBGs) written in a range of fibres and detailed data on their characteristics are presented. The data are fitted to polynomials that may be used in the calibration of temperature measurements with these types of gratings in automated systems. Issues of precision in such measurements from room temperature to 500 °C have been considered using several gratings of type I and IIA written in three different photosensitive fibres, taking into account the non-linear temperature response of the fibre Bragg gratings. Comparisons between the linear and the higher order polynomial regression showed a better performance in calibrated temperature measurement applications when the non-linear temperature coefficients are included, yielding an acceptable rms error of less than or comparable to 1.9 °C, compared to linear regression, with the rms error range of 3.3–7.5 °C for the various gratings studied, over the whole measurement range.