Platinum Resistance Temperature Detector Research Articles

Development and Calibration of a Microfluidic, Chip-Based Sensor System for Monitoring the Physical Properties of Water Samples in Aquacultures.

In this work, we present a compact, bifunctional chip-based sensor setup that measures the temperature and electrical conductivity of water samples, including specimens from rivers and channels, aquaculture, and the Atlantic Ocean. For conductivity measurements, we utilize the impedance amplitude recorded via interdigitated electrode structures at a single triggering frequency. The results are well in line with data obtained using a calibrated reference instrument. The new setup holds for conductivity values spanning almost two orders of magnitude (river versus ocean water) without the need for equivalent circuit modelling. Temperature measurements were performed in four-point geometry with an on-chip platinum RTD (resistance temperature detector) in the temperature range between 2 °C and 40 °C, showing no hysteresis effects between warming and cooling cycles. Although the meander was not shielded against the liquid, the temperature calibration provided equivalent results to low conductive Milli-Q and highly conductive ocean water. The sensor is therefore suitable for inline and online monitoring purposes in recirculating aquaculture systems.

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.

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.

Thin-Film Platinum Resistance Temperature Detector with a SiCN/Yttria-Stabilized Zirconia Protective Layer by Direct Ink Writing for High-Temperature Applications.

In situ temperature monitoring of curved high-temperature components in extreme environments is challenging for a variety of applications in fields such as aero engines and gas turbines. Recently, extrusion-based direct ink writing (DIW) has been utilized to fabricate platinum (Pt) resistance temperature detectors (RTDs). However, the current Pt RTD prepared by DIW technology suffers from a limited temperature range and poor high-temperature stability. Here, DIW technology and yttria-stabilized zirconia (YSZ)-modified precursor ceramic film packaging have been used to build a Pt RTD with high-temperature resistance, small disturbance, and high stability. The results indicate that the protective layer formed by the liquid phase anchors the Pt particles and reduces the agglomeration and volatilization of the Pt sensitive layer at high temperature. Attributed to the SiCN/YSZ protective layer, the temperature resistance curve of the Pt RTD in the range of 50-800 °C has little deviation from the fitting curve, and the fitting correlation coefficient is above 0.9999. Interestingly, the Pt RTD also has high repeatability and stability. The high temperature resistance drift rate is only 0.05%/h after 100 h of long-term testing at 800 °C and can withstand butane flame up to ∼1300 °C without damage. Moreover, the Pt RTD can be conformally deposited on the outer ring of aerospace bearings by DIW technology and then realize on-site, nondestructive, and real-time monitoring of bearing temperature. The fabricated Pt RTD shows great potential for high-temperature applications, and the novel technology proposed provides a feasible pathway for temperature monitoring of aeroengine internal curved hot-end components.

Procedure for the extended calibration of temperature sensors

This paper presents the procedure for the extended calibration of temperature sensors (ECTS) based on the upper bound of dynamic error (UBDE) defined by the integral-square criterion. The proposed procedure is used for the extended calibration of the platinum resistance temperature detector (RTD) and negative temperature coefficient (NTC) temperature sensors. The approach proposed in the paper can be the basis for defining the dynamic accuracy class for the temperature sensors. Therefore, it shows an advantage over the classic method intended for calibrating this type of sensors. Procedure developed in the paper uses the Monte Carlo (MC) method and the fixed point algorithm (FPA) and genetic algorithm (GA). The validation of the obtained results is performed for the first type of sensor and for the ICT sensor. The solutions presented in the paper can be used to compare the UBDEs obtained for different types of temperature sensors.

RapidET: a MEMS-based platform for label-free and rapid demarcation of tumors from normal breast biopsy tissues

The rapid and label-free diagnosis of malignancies in ex vivo breast biopsy tissues has significant utility in pathology laboratories and operating rooms. We report a MEMS-based platform integrated with microchips that performs phenotyping of breast biopsy tissues using electrothermal sensing. The microchip, fabricated on a silicon substrate, incorporates a platinum microheater, interdigitated electrodes (IDEs), and resistance temperature detectors (RTDs) as on-chip sensing elements. The microchips are integrated onto the platform using a slide-fit contact enabling quick replacement for biological measurements. The bulk resistivity (ρB), surface resistivity (ρS), and thermal conductivity (k) of deparaffinized and formalin-fixed paired tumor and adjacent normal breast biopsy samples from N = 8 patients were measured. For formalin-fixed samples, the mean ρB for tumors showed a statistically significant fold change of 4.42 (P = 0.014) when the tissue was heated from 25 °C to 37 °C compared to the adjacent normal tissue, which showed a fold change of 3.47. The mean ρS measurements also showed a similar trend. The mean k of the formalin-fixed tumor tissues was 0.309 ± 0.02 W m−1 K−1 compared to a significantly higher k of 0.563 ± 0.028 W m−1 K−1 for the adjacent normal tissues. A similar trend was observed in ρB,ρS, and k for the deparaffinized tissue samples. An analysis of a combination of ρB, ρS, and k using Fisher’s combined probability test and linear regression suggests the advantage of using all three parameters simultaneously for distinguishing tumors from adjacent normal tissues with higher statistical significance.

Application of 3-omega method for thin-film heat flux gauge calibration

Double-sided thin-film resistance temperature detector (RTD) heat flux gauges (HFGs) are commonly used to characterize heat transfer rates in high-heat flux environments with complex flow features. These gauges comprise two thin-film RTDs on opposing sides of a dielectric. To deduce accurate heat flux, the RTDs must be properly calibrated and the material properties of the dielectric must be characterized. This study presents a complete gauge characterization method for sensors of this type by applying standard calibration procedures with specially-designed RTDs capable of utilizing the 3-omega method. The 3-omega method quantifies the thermal conductivity and thermal product of a material by measuring the response of a specially designed heater/thermometer deposited on the substrate. This study shows the 3-omega method enables RTD calibrations and thermal property determination over a range of temperatures for individual gauges, reducing the uncertainty in calculated heat flux. Although the method is quite general, this study utilized platinum RTDs with a polyimide dielectric, which is common in turbomachinery applications. The thermal properties obtained through this method agree with previous characterization efforts; however, discrete characterization of seven gauges shows that gauge-to-gauge variation in the dielectric could influence measured heat flux by as much as 30%. This study also builds the framework to characterize the thermal conductivity of the adhesive layer beneath the gauge which is necessary to mount the sensors to the test article. Although often uncharacterized, the adhesive thermal conductivity has a significant impact on matching experimental measurements to simulations. Additionally, this study found that if the thermal conductivity of the dielectric is constant (an assumption that holds for the present study), an in-situ RTD calibration can be performed. In-situ RTD calibration and traditional method RTD calibration agreed to within 0.1%. Overall, this work has practical implications in obtaining high quality measurements from HFGs of this type.

PH and Temperature Sensor Platform for Detecting Inflammation at Specific Sites in the Oral Cavity

Our goal is to make electrochemical sensors for measuring oral fluids and tissues to aid in more accurate diagnosis and monitoring of oral diseases. In this work, we developed a sensor platform capable of measuring simultaneously pH and temperature for detecting inflammation at specific sites in the mouth. Miniaturized, planar pH sensing and reference electrodes were combined on a flexible polymer platform along with a platinum resistance temperature detector (RTD) using a combination of microfabrication and electrodeposition techniques. The resistance of the platinum RTD was linear between 20 and 60 °C, with a precision of ±0.1 °C. The pH response and reproducibility of sputtered iridium oxide (IrOx) was compared with those of electrochemically deposited IrOx. The voltage of the pH sensor was measured in solutions of varying pH, chloride concentration, and temperature mimicking the oral environment. At room temperature, sputtered IrOx sensors exhibited a linear response (-47 to -55 mV/pH) for pH 2-10 whereas electrodeposited IrOx was linear (-72 to -82 mV/pH) over pH 4-8, which is within the range expected in the oral cavity. The sensitivity of the sputtered IrOx was more reproducible between individual sensors than electrochemically deposited IrOx; however, sputtered IrOx electrodes were more difficult to fabricate and had a lower sensitivity to pH. Voltage stabilized (within 1-2 mV) in 10-120 s and reached 90 % of this stable value within 5 s at each pH value. The electrodeposited Ag/AgCl reference responded linearly to [Cl-] as well asvaried by <2 mV over pH 4-8. Repetitions of reproducible sensors at one pH were ≈0.1 pH unit. Preliminary measurements indicated that pH sensitivity of the IrOx sensors was ≈0.1 mV/pH/°C, producing an apparent change of ≈0.2 pH between room temperature (21 °C) and the mouth (35 °C); therefore, the voltage will need to be calibrated based on temperature.

A wafer-like apparatus for two-dimensional measurement of plasma parameters and temperature distribution in low-temperature plasmas.

A wafer-type monitoring apparatus that can simultaneously measure the two-dimensional (2D) distributions of substrate temperature and plasma parameters is developed. To measure the temperature of the substrate, a platinum resistance temperature detector is used. The plasma density and electron temperature are obtained using the floating harmonics method, and incoming heat fluxes from the plasma to the substrate are obtained from the plasma density and electron temperature. In this paper, 2D distributions of the substrate temperature, plasma density, and electron temperature are obtained simultaneously for the first time in inductively coupled plasma. The shapes of the 2D distributions of the substrate temperature and incoming heat flux are similar to each other, but some differences are found. To understand that, an energy balance equation for the substrate is established, which shows good agreement with the experimental results. This apparatus will promote the understanding of surface reactions, which are very sensitive to the temperatures and plasma densities in plasma processing.

Finite element analysis of blackbody radiation environment for an ytterbium lattice clock operated at room temperature

The Stark shift due to blackbody radiation (BBR) is a key obstacle limiting the frequency uncertainty of optical lattice clocks. A well-characterized BBR environment is necessary to know exactly the temperature felt by the cold atoms. In our ytterbium clock, the lattice-trapped atoms are exposed to the thermal radiation of the surrounding vacuum chamber walls and optical windows. Calibrated platinum resistance temperature detectors are used to monitor the vacuum chamber temperature in real time. In order to obtain the effective temperature T eff in the position of the atoms, we perform finite element (FE) analysis to the thermal radiation of the vacuum chamber. Due to the temperature inhomogeneity existing in our vacuum chamber, the limited knowledge of the air convection contributes the largest part of the uncertainty in T eff. For our typical room temperature environment, T eff can be determined with an accuracy level of 160 mK, corresponding to a fractional frequency uncertainty of 5.3 × 10−18 for the BBR Stark shift. Additionally, we use a simple formula to relate T eff to the temperatures at the monitored points, which allows us to know the value of T eff without using FE analysis, and thus enables the real-time correction to the BBR Stark shift.

Experimental Comparison of Flow Boiling Heat Transfer in High Aspect Ratio Microchannels With Plain and Grooved Walls

Abstract The dry-out easily occurs on high-aspect ratio microchannel sidewalls due to the decreasing of liquid film thickness. In this paper, the triangular microgrooves possessing the characteristic of evaporating meniscus were designed on the microchannel sidewalls. The heat sink consisted of 33 parallel microchannels, having a hydraulic diameter of 100 μm and an aspect ratio of 4. A platinum film heater and platinum resistance temperature detectors (RTDs) were integrated on the backside of the heat sink to realize uniform heating and precise temperature measurement, respectively. Flow boiling visualization experiments were carried out by high-speed camera in triangular groove-wall and plain-wall microchannels at mass fluxes of 148–490 kg/m2·s and inlet temperatures of 42 °C and 60 °C. The boiling curve, heat transfer coefficient (HTC), pressure drop, and two-phase flow boiling instability were systematically investigated to assess the flow boiling performances. Thin liquid film was observed in the triangular grooves during the dry-out process, compared to the dry-out in plain-wall microchannels. The oscillations of wall temperature, inlet temperature, and pressure drop were significantly suppressed in triangular groove-wall microchannels. Moreover, the earlier onset of nucleate boiling, improved heat flux, and HTC were realized in triangular groove-wall microchannels compared to plain-wall microchannels. Therefore, triangular groove design on the sidewalls is a promising solution to enhance boiling heat transfer and suppress flow boiling instabilities for high-aspect ratio microchannels.

Fluid Temperature Measurement in Aqueous Solution via Electrochemical Impedance

A novel temperature transduction method using the high-frequency electrochemical impedance between a pair of microelectrodes exposed to aqueous solution is reported. The solution resistance of an aqueous ionic solution is highly temperature dependent, and the electrochemical impedance between two microelectrodes is dominated by solution resistance when measured at the appropriate frequency. Therefore, precise measurements of electrochemical impedance at the proper frequency in a two-electrode system can be used to transduce solution temperature. To demonstrate this method, a temperature sensor composed of two thin-film platinum electrodes on a freestanding Parylene C substrate was designed and fabricated. A platinum resistance temperature detector was co-fabricated to provide a simple means of benchmarking against an existing standard. Transduction via electrochemical impedance was achieved by measuring the real part of impedance at the frequency where phase was minimized. Fluid temperature was transduced between 15°C and 50°C with high sensitivity (−1.21%/°C) and resolution (0.02°C). A $4\times $ improvement in sensitivity and resolution over the conventional platinum resistance temperature detector was achieved. The sensor design described here features flexible construction with inert materials which facilitates future use in biomedical or microfluidic applications. [2019-0190]

Focus on materials, semiconductors, vacuum, and cryogenics

Focus on materials, semiconductors, vacuum, and cryogenics

A New Autocalibration Procedure in Intelligent Temperature Transducer

In this paper, a concept of an intelligent temperature transducer (ITT) featuring a new autocalibration procedure cooperating with a platinum resistance temperature detector (RTD) is presented. This procedure is based on the application of resistors representing the standards of the measured temperature. The effect of this procedure is the minimization of linearity errors of the ITT processing characteristic, including the RTD, and the minimization of the ITT offset and gain errors. In the adopted ITT solution, the compensation of the RTD wires resistance is applied. The simulation and experimental research results, which confirm the high effectiveness of this procedure, are presented. The uncertainty of temperature measurement by means of the Monte Carlo method is evaluated and experimental research results, confirming the possibility of measuring temperature within a range of 0 °C–200 °C with a 0.03 °C uncertainty, are presented.

Evaluation of thin film p-type single crystal silicon for use as a CMOS Resistance Temperature Detector (RTD)

Temperature monitoring and thermal management of CMOS circuits / sensors is often required for long term circuit reliability and sensors temperature compensations. The ideal solution is to co-fabricate the temperature sensors along with the CMOS circuits and other sensors using CMOS materials and the same CMOS processes. In this paper we therefore, report on the fabrication and thermal characterization of such thin film temperature sensors. The thin film Resistance Temperature Detectors (RTDs) are made of single crystal p-type silicon on a silicon substrate using a Silicon on Insulator (SOI) Complementary Metal Oxide Semiconductor (CMOS) process. The influence of thin film length and width on the response of RTDs has been investigated. Furthermore, the effects of aluminum (Al) and tungsten (W) metallization used for power tracks on the response of RTDs have been studied. To assess the performance of the RTDs based on SOI CMOS p-type silicon, in addition to sensitivity and TCR, their power consumption, linearity, hysteresis, repeatability, reproducibility and expected life span have also been evaluated. The p-type silicon RTDs consume very less power (i.e. 0.9 μW only) and demonstrate a sensitivity of 13.88 Ω / oC, which is much higher than the previously reported CMOS RTDs and widely used non-CMOS platinum RTDs. The RTDs also exhibit a linear response (98.9% fsd), an excellent repeatability and significantly low hysteresis with maximum variation of 0.2% between forward and reverse cycle. These RTDs also boast good reproducibility, within the wafer and wafer to wafer, with maximum sensitivity variation of 1.3% between different tested samples. The expected life span of the RTD is > 10 years. These inexpensive RTDs are therefore, good candidates for use as temperature sensors on CMOS circuits / sensors system.

Platinum RTD sensor based multi-channel high-precision temperature measurement system for temperature range −100°C to +100°C using single quartic function

A method and system for measuring multiple temperature points using two wire configuration Resistance Temperature Detectors (RTD) for temperature range −100°C to +100°C is mainly composed of the Micro Controller Unit (MCU), analog–digital converter (ADC), reference Voltage source, Multiplexers (MUX) and resistance network including the RTD temperature sensors. The RTDs are sequentially scanned using a reference/constant voltage source, and resistance values of the RTDs are calculated based on the voltage measured across the RTDs and the current sensing resistor. Improving the precision of temperature measurement is based on a line fitting algorithm—Newton’s divided differences interpolation polynomial based on three reference resistor values representing two extreme end points and the center point of the temperature range for which the system is made. The test results show that the device temperature measurement precision can reach ±0.02°C, has the advantage of using a single quartic function for the entire temperature range −100°C to +100°C with dynamic calibration to address errors related to in-circuit resistance, tolerance, temperature coefficient, linearity and offset errors in the circuit, and also supports detection of degradation of linearity and offset in the circuit because of the aging factor.

The effect of human-mattress interface's temperature on perceived thermal comfort

In recent years, methods that allow for an objective evaluation of perceived comfort, in terms of postural, physiological, cognitive and environmental comfort, have received a great deal of attention from researchers. This paper focuses on one of the factors that influences physiological comfort perception: the temperature difference between users and the objects with which they interact. The first aim is to create a measuring system that does not affect the perceived comfort during the temperatures' acquisition. The main aim is to evaluate how the temperature at the human-mattress interface can affect the level of perceived comfort. A foam mattress has been used for testing in order to take into account the entire back part of the human body. The temperature at the interface was registered by fourteen 100 Ohm Platinum RTDs (Resistance Temperature Detectors) placed on the mattress under the trunk, the shoulders, the buttocks, the legs, the thighs, the arms and the forearms of the test subject. 29 subjects participated in a comfort test in a humidity controlled environment. The test protocol involved: dress-code, anthropometric-based positioning on mattress, environment temperature measuring and an acclimatization time before the test. At the end of each test, each of the test subject's thermal sensations and the level of comfort perception were evaluated using the ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) scale. The data analyses concerned, in the first instance, correlations between the temperature at the interface and comfort levels of the different parts of the body. Then the same analyses were performed independently of the body parts being considered. The results demonstrated that there was no strong correlation among the studied variables and that the total increase of temperature at interface is associated with a reduction in comfort.

Calibration of a TFG Sensor for Heat Flux Measurements in a S.I. Engine

In the development of internal combustion engines, measurements of the heat transfer to the cylinder walls play an important role. These measurements are necessary to provide data for building a model of the heat transfer, which can be used to further develop simulation tools for engine optimization. This research will focus on the Thin Film Gauge (TFG) heat flux sensor. This sensor consists of a platinum RTD (Resistance Temperature Detector) on an insulating Macor® (ceramic) substrate. The sensor has a high frequency response (up to 100 kHz) and is small and robust. These properties make the TFG sensor adequate for measurements in the combustion chamber of an internal combustion engine. To use this sensor, its thermal properties - namely the temperature sensitivity coefficient and the thermal product - must be correctly calibrated. First, different calibration setups with a different temperature range are used to calibrate the temperature sensitivity coefficient of the TFG sensor. These results will be analyzed and discussed. Second, the DED (Double Electrical Discharge) calibration setup for the thermal product is extensively discussed.

Zinc Oxide Nanowire Forest for Pool Boiling Heat Transfer

Zinc oxide (ZnO) nanowire forest is applied for the electronics cooling by means of pool boiling heat transfer. The forest was composed of lengthwise grown backbone and branched nanowires, which were highly dense and tree-like hierarchical structures. The platinum heater and resistance temperature detector were fabricated by microfabrication on one side of silicon chips and nanowire forest was synthesized on the other side. The superheat and heat flux were evaluated at steady state while the voltage in the heater was increased gradually. The heat flux gradually increased linearly with superheat at the initial stage of heating due to convective heat transfer and abruptly increased once the coolant started to boil. It seemed that the nanowire forest played a role of increased bubble nucleation sites with superhydrophilic nature leading to enhancement of boiling heat transfer. This sheds light on application of nanostructured surface as an effective electronics cooling by boiling heat transfer.

Focus on lasers and imaging

Focus on lasers and imaging