Resistance Thermometers Research Articles

Assessment of Hysteresis Uncertainty in the Calibration of Platinum Resistance Thermometers

Assessment of Hysteresis Uncertainty in the Calibration of Platinum Resistance Thermometers

Metal-based sandwich type thick-film platinum resistance temperature detector for in-situ temperature monitoring of hot-end components

High-temperature resistance temperature detectors (RTDs) are gaining significant attention for various promising applications, including aeroengines, steel metallurgy, and construction machinery. However, it remains a critical challenge in developing RTDs on curved metal substrates without involving high-cost and complicated manufacturing processes. Herein, a metal-based sandwich type thick-film platinum (Pt) RTD for in-situ temperature monitoring of hot-end components is developed through a facile and high-efficient tape mask process and direct ink writing (DIW) technology. The liquid-formed glass–ceramic insulating layer and protective layer effectively immobilize the Pt particles within a sandwich structure, resulting in adequate protection from volatilization and aggregation of the Pt sensitive layer. Meanwhile, the insulating/protective layer exhibits outstanding insulation performance. Additionally, the fabricated Pt RTD achieved excellent repeatability, ultra-high stability (with a temperature drift rate of 0.7%/h at 800 °C), and high accuracy (0.92% full-scale) in the range of 50–800 °C. As an application example, the Pt RTD was fabricated on the surface of a turbine blade to verify its functionality at temperatures up to 800 °C. The exceptional performance and flexible fabrication process indicate that the Pt RTD is a promising candidate for in-situ temperature monitoring of critical aeroengine components.

Cylindrical Acoustic Gas Thermometry

We review recent determinations of the Boltzmann constant kB and the differences T − T90 that used cylindrical acoustic gas thermometry (c-AGT). These determinations measured the acoustic resonance frequencies of argon gas enclosed by metal-walled, cylindrical cavities. (Here, T is the thermodynamic temperature and T90 is the temperature measured on the International Temperature Scale of 1990, ITS-90.) In the range 234–303 K, the standard uncertainty of c-AGT ranges from 1.9 × 10−6T to 2.6 × 10−6T. This uncertainty is much smaller than the errors in ITS-90; therefore, c-AGT can help improve ITS-90. Moreover, we are extending c-AGT up to 1358 K. With increasing temperatures, c-AGT becomes advantageous relative to AGT based on quasi-spherical cavities because long cylindrical cavities (1) naturally fit into cylindrical heat pipes or multi-shelled thermostats; (2) provide the immersion required by transfer temperature standards, such as long-stemmed platinum resistance thermometers; and (3) have more useful, low-frequency acoustic resonances. In preparation for high-temperature c-AGT, we identified suitable materials for fabricating cylindrical cavities and we developed techniques for measuring acoustic resonance frequencies using sources and detectors outside the high-temperature thermostat. We also considered alternative test gases and optimal dimensions of cavities.

EXPERIMENTAL STUDY OF BATTERY TEMPERATURE UNDER CONSTANT DISCHARGE RATE

This research is about an experimental study of battery temperature under constant discharge rate. This study consider constant discharge rates, constant air velocities, gap between battery cells in the battery module and placement of Resistance Temperature Detector (RTD) sensors to achieve the objective of this experiment studies. The relationship of temperature and discharge rates for different point on battery cell surface is compared. The Lithium-ion battery cells are discharged with a constant discharge current in this experiment. The heat generation on the battery surface as a function of discharge time are linked to the LabVIEW software. An axial fan creates constant air velocities that help in removing heat away from battery module during discharge process. The factors that are considered in this experiment are the discharging rate, air velocities and the thermal behaviour of the Lithium-ion battery cell on various point across the battery surface.

Multimodal CMOS Biosensor for Microbial Growth Monitoring

This paper describes a new biosensor prototype that uses microscale electrodes to measure impedance, pH, and temperature changes caused by bacterial growth <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in-vitro</i> . The prototype uses multiple sensor geometries to optimize sensitivity, and employs custom circuits including an integrated CMOS lock-in amplifier (LIA) for multi-frequency impedance measurement. The gold-plated interdigitated electrodes (AuIDEs), iridium oxide (IrO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> )-based pH electrodes, and snake-shaped gold resistance-temperature detectors (RTDs) electrodes are implemented on a flexible PCB. The custom integrated LIA is designed and fabricated in a 0.18-μm CMOS technology with 1.8 V supply voltage. The overall sensitivity of the LIA is 240 mV/nA with a current detection sensitivity down to 1 pA. A pH measuring circuit is designed using an operational amplifier with a very low input-bias-current. A Wheatstone bridge circuit with a network of resistors and RTD electrode is used to measure RTD resistance changes caused by temperature fluctuations. The whole system is enclosed into a self-contained platform developed to monitor bacterial growth by measuring the impedance as well as the environmental growth parameters such as pH and temperature. The fabricated multi-frequency LIA was employed to test the impedance of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E. coli</i> cells with different concentrations at multiple frequencies. The results showed that the IDE can measure the impedance variation caused by the bacterial activity with sensitivities of 36.62%, 34.37%, 33.29% and 20.23% at 1, 2, 4, and 10 kHz frequency, respectively. The fabricated pH electrodes showed linearity with a linear regression (R <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) value of 0.99 and can measure pH changes ranging from 4 to 10, with a sensitivity of 36, 52, and 68 mV/pH for sensing areas of 4 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , 9 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , and 16 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , respectively. The temperature sensor measurements showed that the 4 mm × 4 mm RTD gold-printed temperature electrodes had a linear relationship between resistance and temperature with a R <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> value of 0.996, and the higher sensitivity of 36 (Ω/°C) compared to other tested RTD geometries. The prototype was successfully used to perform bacterial growth measurements <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in-vitro</i> .

3D printing of high-temperature thick film platinum resistance temperature detector array

Dynamic high-temperature field measurements have garnered substantial interest for various promising applications, such as the health monitoring of aviation components. 3D printing offers unprecedented opportunities for the development of curved structure-function integrated sensors. However, most current resistance temperature detector (RTD) arrays based on 3D printing technology work well only within a narrow temperature range. Their application at high temperatures remains a significant challenge because of the lack of efficient manufacturing processes. Herein, a high-temperature thick film platinum (Pt) RTD array is presented based on 3D printing technology, suitable for high-temperature field measurement sensing applications at 50−800 °C. Three stages of Pt film sintering were revealed through the analysis of the microstructure, phase composition, and electrical properties during the sintering process. Compared to sputtered films, printed Pt films, which are confirmed to contain glass powder, exhibit excellent anti-aggregation and high-temperature properties. The resulting Pt RTD array shows outstanding stability (drift rate of 0.07%/h at 800 °C), high accuracy (0.75% full-scale), and can realize temperature gradient monitoring of a two-dimensional temperature field. The potential applications of the Pt RTD array, including bolt and rocket engine tester exhaust flame temperature monitoring, were demonstrated. This study paves the way for printing RTD arrays directly on curved parts.

The effect of metal quantity on the temperature plateau time

In recent years, the miniaturization and portability of fixed-point containers are becoming a trend. This paper introduces a sealed small container, which is filled with 99.9999% high purity tin, with related reproducing experiments carried out in a Fluke dry-well furnace. A precision platinum resistance thermometer with 3.6 mm diameter is put into the bottom of the temperature well for running several tests. The differences in temperature plateau time are compared between the 40 g case and the 16 g case. The data shows that the reduction of the tin filling can significantly shorten the temperature plateau time.

Improvement of Algorithms for Measuring Temperature with Two-Wire Connection of Resistance Thermometers

Improvement of Algorithms for Measuring Temperature with Two-Wire Connection of Resistance Thermometers

Multichannel Generator Time-To-Pulse Converter of the Telemetry Temperature Measurement System

The article considers the multichannel time-to-pulse intermediate converter as a part of telemetric temperature measurement system. The principle of operation is based on the use of aperiodic transient in a first-order circuit formed by resistance temperature device and capacitor. Switching of resistance temperature device in the process of temperature measurements is carried out by MIS keys (metal-insulator-semiconductor) according to the signal from the output of the circuit, and the allocation of the output information interval is carried out by a voltage comparator. The article illustrates an electric circuit of a time-to-pulse converter. Based on the equivalent scheme, the main metrological characteristics were obtained by calculation, namely, the dependences of the sensitivity of the output value of the converter to changes in the parameters of the circuit elements expressed in terms of temperature. The scheme of a time-to-pulse converter with an optical output, designed for use with semiconductor resistance temperature devices was experimentally investigated. Variants of multichannel converters for 7 and 15 measuring channels are implemented. Digital elements of the MIS-type (metal-insulator-semiconductor) are used. Information about the temperature at the output of the converters was encoded in the duration of 128 periods of pulse signals, which ensured reliable of information intervals in the receiving part of the equipment. A laboratory tester with an optoelectronic input was used as a receiver of optical pulses. The duration of the information intervals was measured by an industrial measuring device with a resolution of 10 billiseconds. The experimental and rated characteristics of the conversion and the dependence of the conversion error on the supply voltage, operating temperature and resistance of primary thermal converters are presented. It is established that in terms of the main operational parameters, a generator-type time-to-pulse converter is not inferior to a circuit with external excitation. At the same time, the generator converter is less sensitive to the errors of the comparator in terms of electrical bias and speed. The use of a multichannel generator time-to-pulse converter is advisable in telemetric temperature measurement systems when transmitting information in a communication channel during the duration of the period of information, in particular, optical pulses.

Achieving simultaneous sensing of oxygen and temperature with metalloporphyrins featuring efficient thermally activated delayed fluorescence and phosphorescence

Temperature is an essential parameter for reliable assessment of oxygen concentration by optical sensors. This can be done by a conventional sensor such as a resistance thermometer or by adding an optical temperature probe to the sensing material. A sensor that relies on a single emitter capable of simultaneous sensing of oxygen and temperature would be highly advantageous. Unfortunately, such materials are extremely rare and moreover poorly suitable for measurement at ambient temperatures and physiological conditions. To cover this gap, we systematically investigated 15 Pd(II) and 6 Pt(II) complexes of π-extended porphyrins that simultaneously emit thermally activated delayed fluorescence (TADF) and phosphorescence. The class of quinone-extended benzoporphyrins was found to feature especially high ratios of TADF to phosphorescence (1.4–2.7 and 0.10–0.21, for Pd(II) and Pt(II) complexes, respectively, at 25 °C) which represents approximately a sixteen-fold improvement compared to the benchmark octasulfone-substituted porphyrins. Interconversion of phosphorescence into TADF with increasing temperature enables ratiometric measurement of this parameter in the range from 0 to about 65 °C whereas the oxygen concentration is accessed through the decay time of either TADF or phosphorescence. Simultaneous sensing of both temperature and oxygen is demonstrated for a naphthoquinone-extended Pt(II) benzoporphyrin embedded in polystyrene that shows dual emission with maxima at 677 and 789 nm. The sensor is characterized for temperatures from 5° to 55 °C and oxygen partial pressure from 0 to 202 hPa, corresponding to the conditions found in the majority of applications. As an application example temperature compensated imaging of oxygen distribution is demonstrated.

Experimental investigation on supersonic film cooling of hypersonic optical dome under different nozzle pressure ratios

When an aircraft flies at hypersonic speeds in the atmosphere, its optical window is subjected to severe aerodynamic heating. To investigate the supersonic film cooling laws of hypersonic optical dome, three supersonic (Mach 2.35) film generation devices with different jet outlet heights (1 mm, 2 mm, 3 mm) were designed. The experiments were conducted in a hypersonic (Mach 7.1) gun wind tunnel. The NPR (nozzle pressure ratio = jet outlet static pressure/nearby mainstream static pressure) ranged from 0 to 2.3. The heat flux on the window surface was measured by the thin film resistance thermometer. Experimental results indicate that, under different jet outlet heights, the film cooling effectiveness increased gradually as the NPR increased, corresponding to an increase in effective cooling length. The existing similarity parameters for film cooling could effectively predict the effective cooling length of supersonic film when NPR = 1. However, the prediction effect deviated significantly when NPR ≠ 1. Moreover, the effective cooling length corresponding to the unit mass flow rate of the coolant first increased and then decreased with the increase of NPR, and there existed an optimal solution. Furthermore, with the same coolant mass flow rate, higher jet Mach number lead to better supersonic film cooling performance.

Direct Fabrication of a Copper RTD over a Ceramic-Coated Stainless-Steel Tube by Combination of Magnetron Sputtering and Sol–Gel Techniques

Reducing the economic and environmental impact of industrial process may be achieved by the smartisation of different components. In this work, tube smartisation is presented via direct fabrication of a copper (Cu)-based resistive temperature detector (RTD) on their outer surfaces. The testing was carried out between room temperature and 250 °C. For this purpose, copper depositions were studied using mid-frequency (MF) and high-power impulse magnetron sputtering (HiPIMS). Stainless steel tubes with an outside inert ceramic coating were used after giving them a shot blasting treatment. The Cu deposition was performed at around 425 °C to improve adhesion as well as the electrical properties of the sensor. To generate the pattern of the Cu RTD, a photolithography process was carried out. The RTD was then protected from external degradation by a silicon oxide film deposited over it by means of two different techniques: sol–gel dipping technique and reactive magnetron sputtering. For the electrical characterisation of the sensor, an ad hoc test bench was used, based on the internal heating and the external temperature measurement with a thermographic camera. The results confirm the linearity (R2 &gt; 0.999) and repeatability in the electrical properties of the copper RTD (confidence interval &lt; 0.0005).

A Cu/Ni alloy thin-film sensor integrated with current collector for in-situ monitoring of lithium-ion battery internal temperature by high-throughput selecting method

The high-energy-density lithium-ion batteries (LIBs) are susceptible to thermal runaway and lead to safety incidents. Monitoring the internal temperature of LIBs is a promising way to forewarn its thermal runaway. However, the current external temperature sensors show high delay and poor accuracy, and the built-in temperature sensors are incompatible with the assembly process and may damage the battery. Thus, a reliable real-time internal battery temperature monitoring sensor is desired. In this study, a high-throughput selected thin-film resistance temperature detector (TFRTD) is proposed. The TFRTD is integrated between the collectors of the pouch LIB, which is compatible with the battery assembly process. The built-in TFRTD responds 82% faster and measures 33% more accurately than an external RTD, allowing real-time monitoring of internal battery temperature at different current rates. With a discharge rate of 0.5 C, the internal temperature can be monitored to be 0.57 °C higher than the external temperature in a battery with a capacity of only 0.1 Ah. Cycling tests show that the battery with a built-in TFRTD has a capacity retention rate of 92.71% after 100 cycles, and the TFRTD has a limited impact on battery performance. Therefore, the developed novel TFRTD can be used to analyze the battery heating process under different conditions and has some potential for engineering applications.

The Effect of the Conversion Coefficients of Platinum-Based Resistance Thermometers on the Uncertainty Estimation

Different types of thermometers (resistance thermometers, thermocouples, liquid in glass thermometers, radiation thermometers, etc.) are used in temperature measurements. Resistance thermometers are among the most reliable types of sensors used for sensitive temperature measurements. The traceability, accuracy and precision of the measurement results are important for the reliability of the measurements. There are many parameters that affect the uncertainty estimation in measurements made with resistance thermometers. One of the parameters to be considered in the uncertainty estimation is the interpolation error in converting the resistance value to temperature. Different methods (ITS-90, Calendar Van Dusen CVD, Polynomial equation) can be used to convert the resistance value to temperature. The problem is that there are differences in the temperature values read using the coefficients obtained by different methods. In this study, the effect of errors from CVD and polynomial equation methods on measurement uncertainty was investigated.

Real-time nondemolition measurement method for alkali vapor density and its application in a spin-exchange relaxation-free co-magnetometer.

This study presents a novel method for measuring the number density of K in K-Rb hybrid vapor cells using circularly polarized pump light on polarized alkali metal atoms. This proposed method eliminates the need for additional devices such as absorption spectroscopy, Faraday rotation, or resistance temperature detector technology. The modeling process involved considering wall loss, scattering loss, atomic absorption loss, and atomic saturation absorption, with experiments designed to identify the relevant parameters. The proposed method is real-time, highly stable, and a quantum nondemolition measurement that does not disrupt the spin-exchange relaxation-free (SERF) regime. Experimental results demonstrate the effectiveness of the proposed method, as the longitudinal electron spin polarization long-term stability increased by 204% and the transversal electron spin polarization long-term stability increased by 44.8%, as evaluated by the Allan variance.

Response Time of a Thin-Film Resistance Temperature Detector (RTD) for High-Intensity Focused Ultrasound (HIFU) Phantom Applications

The thermal response time of a thin-film resistance temperature detector (RTD) array sensor was measured for a high-intensity focused ultrasound (HIFU) phantom. As the temperature inside materials change rapidly within several seconds, it is important to have a temperature sensor with a fast response time to evaluate their performance. However, previous methods for measuring thermal response time were not suitable for thin-film sensors, and there were no quantitative data available. In this study, we used a liquid drop method to measure the thermal time constant of the thin-film RTD, which was found to be 1.0 ± 0.2 ms. This indicates that the thin-film RTD array sensor has a sufficiently fast response time to detect sudden temperature changes inside the tissue-mimicking material (TMM) for validating HIFU devices.

Thin-Wire Thermocouple Design for Exhaust Gas Temperature Pulse Measurements in Internal Combustion Engines

&lt;div&gt;Accurate exhaust gas temperature (EGT) measurements are vital in the design and development process of internal combustion engines (ICEs). The unsteady ICE exhaust flow and thermal inertia of commonly used sheathed thermocouples and resistance thermometers require high bandwidth EGT pulse measurements for accurate cycle-resolved and mean EGTs. The EGT pulse measurement challenge is typically addressed using exposed thin-wire resistance thermometers or thermocouples. The sensor robustness to response tradeoff limits ICE tests to short durations over a few exhaust conditions. Larger diameter multiwire thermocouples using response compensation potentially overcomes the tradeoff. However, the literature commonly adopts weaker slack wire designs despite indications of coated weld taut wires being robust. This study experimentally evaluates the thin-wire thermocouple design placed in the exhaust of a heavy-duty diesel engine over wide-ranging exhaust conditions for improving both sensor robustness and accuracy of the measured EGT. The assessed design parameters included the wire diameter (51 μm to 254 μm), the exposed wire length, and the wires placed slack or taut with coated weld faces. All taut wires with ceramic-coated weld faces endured over 3 h of engine operation, while similar diameter slack wires (51 μm and 76 μm) were sensitive to the exhaust condition and exposed wire length. Reducing the wire diameter from 76 μm to 51 μm significantly impacted response improvements as evidenced at certain test conditions by a peak-peak EGT increase of 92 °C, a mean EGT drop of 26 °C, and a doubling of the sensitivity of mean EGT cycle-to-cycle variations to ±12 °C. Increasing the exposed wire length showed less significant response improvements. The Type-K thin-wire thermocouples showed negligible drift, thereby indicating the possibility of using smaller and longer wires built taut with coated weld faces for improved accuracy of EGT measurements in ICEs.&lt;/div&gt;

A millikelvin precision temperature control system designed for a low cost, portable and variable temperature blackbody from 298.15 to 693.15 K

Millikelvin precision portable variable temperature blackbody from 298.15 to 693.15K is very important in the on-site calibration of infrared measuring instruments. The stability of the blackbody temperature directly affects the calibration quality. However, the temperature measurement and control system is the key component to guarantee the stability of the blackbody temperature. In this article, a measurement and control system of the low-cost and portable blackbody was designed and verified. A Pt100 platinum resistance thermometer was employed to measure the temperature of the blackbody radiation source. Based on the round-robin structure and current reversing technology, the precision of the temperature measurement achieved a sub-millikelvin level. To overcome the drawbacks that traditional proportional integral derivative (PID) controller would lead to large overshoot and long adjustment time during the temperature control of the large thermal inertia blackbody, a feedforward and segmented PID controller was introduced to improve the dynamic performance of the blackbody radiation source. The experimental results showed that the precision of the temperature measurement at 0.5Hz was better than 0.5 mK and the temperature stability within 10minwas better than 3 mK in the temperature range from 298.15 to 693.15K. Hence, the millikelvin precision measurement and control system has a strong prospect for practical application in high-performance blackbody development.

Internal Dynamic Temperature Measurement of Alkali Metal Vapor Cell by Kalman Filter

Measuring the internal dynamic temperature of alkali metal vapor cells is crucial for enhancing the performance of numerous atomic devices. However, conventional methods of measuring the internal dynamic temperature of the cell are prone to errors. To obtain a more accurate internal dynamic temperature of the alkali metal vapor cell, a temperature measuring method based on the data fusion of the Kalman filter has been proposed. This method combines the indirect temperature measurement signal from a resistance temperature detector with the atomic absorption spectrometric temperature measurement signal. This provides a high-accuracy set of internal dynamic temperatures in the cell. The atomic vapor density calculated from the final fusion results is 37% average lower than that measured by external wall temperature measurements, which is in line with the conclusions reached in many previous studies. This study is highly beneficial to measure the temperature of alkali metal vapor cells.

Investigations of Type 3 non-uniqueness in standard platinum resistance thermometers between 83 K and 353 K

A key feature of the International Temperature Scale of 1990 (ITS-90) is Type 3 non-uniqueness which arises from differences between individual Standard Platinum Resistance Thermometers (SPRTs) over a given subrange. This can be significant in the context of the best reported uncertainties of SPRT calibrations, but it is extremely difficult to determine because it is easily obscured by the measurement uncertainties. Hence, there is little good information available, particularly over much of the temperature range commonly encountered by long-stem SPRTs, and the estimates of its magnitude are potentially overstated. This paper presents high precision comparisons at NPL and CEM of two cohorts of 8 and 6 long-stem SPRTs, by measuring the ratio of each SPRT against a common SPRT in stirred liquid baths at temperatures from 178 K to 303 K, and 274 K to 353 K, respectively. Measurements of a third cohort of 8 SPRTs were made at INTiBS in a stirred liquid bath from 198 K to 303 K and in a temperature-controlled cryostat from 84 K to 185 K. The measurements were augmented by calibrations of each SPRT at the triple points of argon and mercury, the melting point of gallium and the freezing point of indium, so extending the overall temperature range down to 84 K and up to 429 K. The three cohorts were linked by two SPRTs which were common to all of them. The comparison differences, which ideally should represent the Type3 non-uniqueness, are presented for the specified ITS-90 interpolations, and for some alternative interpolation schemes. Specifically, it is assessed for interpolations in which the mercury triple point is replaced with the triple point of Xe, CO2 or SF6, which are widely considered to be potential candidates for replacing mercury in a future amendment of the ITS-90. The further alternative of using the melting point of gallium is also investigated.