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An A site disordered rare earth-based perovskite-derived structured new compound is synthesized using low-cost solid-state reaction method. The phase formation of the desired compound is established through the X-ray diffraction technique. Rietveld analysis of the obtained XRD data confirmed that the compound exhibits orthorhombic symmetry with pbnm space group which is further supported through Raman spectroscopic analysis. The surface morphology and microstructure analysis of the synthesized compound is carried out using scanning electron microscopy approach. The optical properties study done through UV–Visible absorption spectroscopy suggests possible application in optoelectronic devices. The frequency and temperature dependence of dielectric properties are studied for the analysis of electric polarisation in the sample. Electrical properties study conducted through complex impedance spectroscopy approach disclosed the dominant contribution of grain to the electrical response of the material with temperature dependent relaxation process in the compound. The effect of temperature on the dc resistance is further analysed to find the suitability of the material for thermistor application. The frequency dependent data of ac conductivity follows Jonscher's power law. The temperature dependent ac conductivity graph was used to estimate the activation energy in order to identify the specific charge species engaged in the ac conduction process. [ABSTRACT FROM AUTHOR]

Recent methods using thermistors as an early detection of skin cancer require the higher resolution of 5 mK. Previously, the authors developed a vacuum insulated temperature device that calibrates the resistance temperature characteristics of thermistors, so that it improves the temperature resolution and accuracy of skin cancer diagnosis. In this study, the operational methods of the calibration system were compared for improving further accuracy using the temperature calibration device and the oil tank calibration device. The results of the comparison indicated that the temperature calibration device is probably as accurate as the oil tank calibration device. [ABSTRACT FROM AUTHOR]

External electric and mechanical stimuli can induce shape deformation in excitable media because of its intrinsic flexible property. When the signals propagation in the media is described by a neural network, creation of heterogeneity or defect is considered as the effect of shape deformation due to accumulation or release of energy in the media. In this paper, a temperature-light sensitive neuron model is developed from a nonlinear circuit composed of a phototube and a thermistor, and the physical energy is kept in capacitive and inductive terms. Furthermore, the Hamilton energy for this function neuron is obtained in theoretical way. A regular neural network is built on a square array by activating electric synapse between adjacent neurons, and a few of neurons in local area is excited by noisy disturbance, which induces local energy diversity, and continuous coupling enables energy propagation and diffusion. Initially, the Hamilton energy function for a temperature-light sensitive neuron can be obtained. Then, the finite neurons are applied noise to obtain energy diversity to explore the energy spread between neurons in the network. For keeping local energy balance, one intrinsic parameter is regulated adaptively until energy diversity in this local area is decreased greatly. Regular pattern formation indicates that local energy balance creates heterogeneity or defects and a few of neurons show continuous parameter shift for keeping energy balance in a local area, which supports gradient energy distribution for propagating waves in the network. [ABSTRACT FROM AUTHOR]

Mechanically deformable flexible temperature sensors are being used to fabricate next-generation smart electronics, but improving their high-temperature application range is still a major challenge. In this work, in pursuit of excellent performance, a series of Mn–Ni–O ultrathin flexible thermal thin films with dual-phase structure were successfully prepared by magnetron sputtering using the bias voltage adjustment method. The interactions of grain density, ionic valence and phase structure on the performance of high-temperature NTC are emphasized. By overcoming the significant drawbacks of the flexible thermal films such as poor stability and narrow temperature range under high temperature conditions, excellent thermal performance with a wide temperature range from 200 °C to 600 °C and a resistance drift rate as low as 1.5 % has been achieved. This opens up innovative prospects for the design and application of flexible high-temperature thermal materials. [ABSTRACT FROM AUTHOR]

Temperature can reflect vital activities, and researchers have attempted to guide Chinese medicine diagnosis and treatment by observing acupoint temperature changes. Integrating a temperature sensor at the needle tip enables in situ acupoint temperature measurement. However, the sensor needles for acupoint temperature monitoring designed in previous studies were fabricated by manually soldering thermistor beads and metal wires, making mass production difficult. In this work, using MEMS manufacturing technology, a flexible temperature sensor that can be integrated at the needle tip is proposed and can be mass-produced on silicon wafers. The sensor uses a Pt thermistor as the temperature-sensing element and has a slender flexible structure with dimensions of 125 μm width by 3.2 cm length. As the sensor is inserted into a hollow needle, the Pt thermistor is glued to the needle tip. In the temperature range of 30 °C to 50 °C, the fabricated temperature sensor has a sensitivity of 5.00 Ω∙°C−1, a nonlinearity of ±0.39%FS, and a repeatability error of ±2.62%FS. Additionally, the sensor has been applied to in vivo acupoint temperature monitoring experiments in rats and demonstrated good performance, suggesting its promise for future research on acupoint temperature. [ABSTRACT FROM AUTHOR]

Owing to the variation of the characteristics due to the cationic substitution of diverse elements at both A and B sites, the new polycrystalline double perovskite BaBiFeMnO 6 , synthesized via a cost-efficient solid-state reaction route. Initial structural refinement by Rietveld analysis reveals material crystallised in dual phases i.e. monoclinic and orthorhombic. The respective cell parameters for monoclinic as well as orthorhombic phases are a = 5.5881 Å, b = 5.6541 Å, c = 7.9186 Å with cell angles α = γ = 900 and β = 89.90810 and a = 5.4807Å, b = 5.3583Å, c = 7.4045Å and refined angles are α = β = γ = 900 respectively. The microstructural interpretation of the present sample reflects a non-uniform distribution of the grains with an average grain size of 2.97 μm with a mean crystalline size of 342.65 nm. The Fourier-Transform Infrared Spectroscopy (FTIR) graph indicated that the sample belongs to the perovskite family. The impedance measurement was carried out in a selected frequency and an assigned temperature range to investigate the electrical features of the material which suggested the non-Debye type relaxation and negative temperature coefficient of resistance (NTCR). Furthermore, the thermistor constant (β) and temperature coefficient of resistance (TCR) contributed to investigating the NTCR characteristic of the sample under NTC-type thermistor applications. The room temperature dielectric constant is 1707.67 with a minimal tangent loss of 0.7069 at 100Hz frequency has been estimated by fitting the dielectric data by utilizing the Havrilliak-Negami function. The polarization (P) induced due to the maximum applied electric field of 1.287 kV is studied from the hysteresis loop plotted between them. The hysteresis loop indicates the ferroelectric property of the material with a lossy nature. The room temperature remnant magnetization (2M r) of 0.4424 emu/g and coercivity (2H c) of 6.2 kOe have been estimated from the M ∼ H loop. The potentiality of the material to be used as a viable candidate in various energy storage devices and supercapacitors is suggested by all of the characterisations in conjunction with the high value of ε r i.e. ∼80000 at 300 °C for the lower frequency. [ABSTRACT FROM AUTHOR]

This paper addresses the second-order nonlocal dynamic thermistor problem with two-point boundary conditions on time scales. Utilizing the fixed point theorems by Schaefer and Rus, we establish some sufficient conditions for the existence and uniqueness of solutions. Furthermore, we discuss the continuous dependence of solutions and four types of Ulam stability. We provide examples to support the applicability of our results. [ABSTRACT FROM AUTHOR]

An electrothermal analysis for barium-titanate-based ceramics is presented, combining the Heywang–Jonker model for the electric resistivity with a heat dissipation mechanism based on natural convection and radiation in a one-dimensional model on the device level with voltage as the control parameter. Both positive-temperature-coefficient (PTC) and negative temperature coefficient (NTC) effects are accounted for through the double Schottky barriers at the grain boundaries of the material. The problem formulated in this way admits uniform and non-uniform multiple-steady-state solutions that do not depend on the external circuit. The numerical bifurcation analysis reveals that the PTC effect gives rise to several multiplicites above the Curie point, whereas the NTC effect is responsible for the thermal runaway (temperature blowup). The thermal runaway phenomenon as a potential thermal shock could be among the possible reasons for the observed thermomechanical failures (delamination fracture). The theoretical results for the NTC regime and the thermal runaway are in agreement with the experimental flash sintering results obtained for barium titanate, and 3% and 8% yttria-stabilized zirconia. [ABSTRACT FROM AUTHOR]

An electrothermal analysis for barium-titanate-based ceramics is presented, combining the Heywang–Jonker model for the electric resistivity with a heat dissipation mechanism based on natural convection and radiation in a one-dimensional model on the device level with voltage as the control parameter. Both positive-temperature-coefficient (PTC) and negative temperature coefficient (NTC) effects are accounted for through the double Schottky barriers at the grain boundaries of the material. The problem formulated in this way admits uniform and non-uniform multiple-steady-state solutions that do not depend on the external circuit. The numerical bifurcation analysis reveals that the PTC effect gives rise to several multiplicites above the Curie point, whereas the NTC effect is responsible for the thermal runaway (temperature blowup). The thermal runaway phenomenon as a potential thermal shock could be among the possible reasons for the observed thermomechanical failures (delamination fracture). The theoretical results for the NTC regime and the thermal runaway are in agreement with the experimental flash sintering results obtained for barium titanate, and 3% and 8% yttria-stabilized zirconia.

The ceramic oxide Na2Ba2Pr2W2Ti4Nb4O30 (NBPWTN) is prepared by a mechanical mixed oxide route. The compound formation and the phase are concluded from the x‐ray diffraction pattern taken at room temperature (XRD). The uniform distribution of grains of various sizes with negligible voids is studied from scanning electron micrograph of the sample pellet. The presence of dielectric dispersion and ferroelectric phase in the material is observed from the temperature‐dependent dielectric parameters at selected frequencies. The existence of ferroelectricity in the material is further confirmed by the room temperature hysteresis loop. Impedance spectroscopic studies informed about the correlation between the microstructure and electrical behavior. The frequency variation of AC conductivity refers to Jonscher's law. The temperature variation of frequency exponent term n indicates OLPT (overlapping large polaron‐tunneling) model of the conduction mechanism in the sample. NBPWTN is a strong candidate for applications involving thermistor‐related devices because of the temperature dependency of resistance. The value of temperature sensitivity coefficient β in our investigation is achieved between 2000 and 11 000 K, confirming that the material has a high‐temperature stability property and is ideal for high‐temperature electronics applications. The high room temperature dielectric constant value of the ceramic (around 500) is useful for dielectric capacitor applications. [ABSTRACT FROM AUTHOR]

Patterning graphene onto polymeric materials offers benefits in realizing flexible, stretchable, and wearable multifunctional electrodes. However, the employed integration approaches and use of non‐patternable polymers hinder the patterning of graphene at the sub‐millimeter (mm) scale. Serpentine‐shaped thermally active graphene patterns (thermistors) of 500 × 500 µm2 area are reported by the seamless integration of chemical vapor‐deposited graphene (GCVD) into readily available SU‐8 polymer with MEMS‐compatible cleanroom fabrication processes. The thermistor resistance decreases with an increase in graphene temperature changed by local heat conduction or environmental thermal radiations; hence, exhibits a negative temperature coefficient (NTC) of resistance of 0.0012/°C. Furthermore, very fast resistive switching with 1 s response and 3.2 s recovery time is observed under cyclic heating and cooling. Several application scenarios including, monitoring of surface temperature (e.g., kettle and human body), rapid response (0.25 s) to heat conduction and radiations (0.5 s) from human finger at room temperature for contact and touch‐free proximity switching (e.g., turn ON and OFF an LCD display) are demonstrated. Moreover, owing to its small area less than a ceramic resistor enabled to integrate the fabricated thermistor onto a printed circuit board (PCB) to construct a fully packaged thermometer to monitor ambient temperature. [ABSTRACT FROM AUTHOR]

Resistive and diode temperature sensors based on silicon nanowires (SiNWs) are fabricated. Silicon nanowires are obtained by two-stage metal- assisted chemical etching (MACE) technique. The influence of SiNWs synthesis parameters on device characteristics is investigated. In particular, the influence of the duration of the first and second stages of MACE, the content of solutions based on AgNO3 and H2O2, the presence of textured surface of silicon wafer before the MACE process, additional processing in an isotropic/anisotropic etchant after the MACE process on the characteristics of temperature sensors is determined. The electrical and thermosensitive parameters for obtained sensors are calculated, namely, resistance, rectifying coefficient, and coefficient of thermosensitivity. A significant influence of the MACE-process parameters on the lateral roughness and volume porosity of the thermosensitive surface is determined. As established, the following technological operations lead to an increase in resistance: a raise in the deposition time of silver nanoparticles and the use of additional post-chemical treatment, as well as a decrease in the etching time and a decrease in the amount of H2O2. The resistance of the array of silicon nanowires is in the range of 27.6–199.6 Ω. As established, the following process parameters improve the rectifying characteristics: increasing the content of hydrogen peroxide, the presence of preliminary texturing of silicon surface, as well as the use of additional post-chemical treatment in an acid etchant. The maximum rectifying coefficient of diode temperature sensors is of 2503. Significant impact of process parameters on the lateral roughness and bulk porosity of the thermosensitive surface is revealed. As found, the thermal sensitivities of both diode sensors and resistive ones are improved with the increase of MACE first-stage parameters and the decrease of MAСЕ second-stage parameters, as well as in the presence of acid etching treatment. The maximum thermal sensitivity coefficient of thermistors based on silicon nanowires is of 2336 ppm/K, while, for thermodiodes, this coefficient is of 2.5 mV/K. [ABSTRACT FROM AUTHOR]

From the phase diagram it is clear that the Fe0,67Sb0,33 – Pb system is quasi-binary and has a eutectic type of phase formation. The solid solution region with a boundary of ~4 mol% Pb at 300K was discovered in the system. Based on the temperature dependence of the contact resistance of the eutectic Fe0,67Sb0,33 and the solid solution alloy (Fe0,67Sb0,33)0,99Pb0,01, it was established that the contact resistance of these materials varies within 8·10-4 ÷ 5·10-4 om·sm², which makes them promising for use as switching layers in thermoelectric converters. It has been determined that the solid solution with the specified composition is also suitable for the manufacture of low-resistance thermistors. [ABSTRACT FROM AUTHOR]

Abstract Patterning graphene onto polymeric materials offers benefits in realizing flexible, stretchable, and wearable multifunctional electrodes. However, the employed integration approaches and use of non‐patternable polymers hinder the patterning of graphene at the sub‐millimeter (mm) scale. Serpentine‐shaped thermally active graphene patterns (thermistors) of 500 × 500 µm2 area are reported by the seamless integration of chemical vapor‐deposited graphene (GCVD) into readily available SU‐8 polymer with MEMS‐compatible cleanroom fabrication processes. The thermistor resistance decreases with an increase in graphene temperature changed by local heat conduction or environmental thermal radiations; hence, exhibits a negative temperature coefficient (NTC) of resistance of 0.0012/°C. Furthermore, very fast resistive switching with 1 s response and 3.2 s recovery time is observed under cyclic heating and cooling. Several application scenarios including, monitoring of surface temperature (e.g., kettle and human body), rapid response (0.25 s) to heat conduction and radiations (0.5 s) from human finger at room temperature for contact and touch‐free proximity switching (e.g., turn ON and OFF an LCD display) are demonstrated. Moreover, owing to its small area less than a ceramic resistor enabled to integrate the fabricated thermistor onto a printed circuit board (PCB) to construct a fully packaged thermometer to monitor ambient temperature.

This work introduces a novel scheme for driving light-emitting diodes (LEDs) with thermal compensation. The primary objective of the system is to address the issue of emitted light intensity drift caused by temperature variations, with a particular focus on the automotive industry. The developed technique proposes an alternative approach to the traditional thermal approach, which primarily focuses on heat dissipation. In contrast, the presented strategy utilizes a temperature-dependent element, such as a thermistor, to generate a reference current that increases with temperature. The generated current is then amplified by a commercial integrated driver and employed to bias the LEDs. Consequently, the reduction in the emitted light intensity resulting from an increase in the internal temperature of the LED is counterbalanced by an elevation in the bias current. The luminous flux model developed for the proposed system predicts the attainment of stable light intensity across a wide temperature range. The proposed strategy has been applied to three commercial LEDs commonly employed in automotive signal lighting to produce red, yellow, and white light. Experimental results confirm a significant reduction in the thermal dependence of the luminous flux, with reduction factor of temperature dependence ranging between 3.7 and 14.2 for the least and most temperature-sensitive LED models analyzed, respectively.

Introduction. Electric boilers are considered as an important element of the energy transition from the use of hydrocarbon fuels to renewable energy. Electric boiler is one of the popular solutions of “Power-to-Heat” technology, widely used in households for heating with water systems with radiators and low-temperature heating devices of the “floor heating” type. The paper considers a variant of Joule heating of the coolant of heating systems, by means of which heat is released when an electric current passes through a conductive element.Materials and methods. The object of the research is the variants of designs of heat exchangers for generating heat energy using resistor heating elements of normal conductor and semiconductor type. Various variants of indirect heating of the coolant and contacts of the surface of the heating elements with the coolant are considered. Methods of comparative analysis and scoring of the applicability of various designs are used in the work.Results. The classification of electric boilers by types of heating resistors, by contact, by placement of heating elements in the heat exchanger, by the shape of the heat exchanger, by the variant heating element contact with the coolant is presented. A comparative comprehensive analysis of variants of electric heat generators is given.Conclusions. The results of comparative analysis of design variants of electric boilers show the prospectively of using semiconductor thermistors as heating elements. According to the design of the heat energy generation chamber in terms of compactness, power density and reduction of precipitation conditions for coolant stiffness, channel plate electric heat exchangers are the most effective.

Temperature can reflect vital activities, and researchers have attempted to guide Chinese medicine diagnosis and treatment by observing acupoint temperature changes. Integrating a temperature sensor at the needle tip enables in situ acupoint temperature measurement. However, the sensor needles for acupoint temperature monitoring designed in previous studies were fabricated by manually soldering thermistor beads and metal wires, making mass production difficult. In this work, using MEMS manufacturing technology, a flexible temperature sensor that can be integrated at the needle tip is proposed and can be mass-produced on silicon wafers. The sensor uses a Pt thermistor as the temperature-sensing element and has a slender flexible structure with dimensions of 125 μm width by 3.2 cm length. As the sensor is inserted into a hollow needle, the Pt thermistor is glued to the needle tip. In the temperature range of 30 °C to 50 °C, the fabricated temperature sensor has a sensitivity of 5.00 Ω∙°C−1, a nonlinearity of ±0.39%FS, and a repeatability error of ±2.62%FS. Additionally, the sensor has been applied to in vivo acupoint temperature monitoring experiments in rats and demonstrated good performance, suggesting its promise for future research on acupoint temperature.

I discuss the TPHP soil moisture content and temperature measuring digital system using Indium doped Tin Oxide nanopowder (ITO) electric heater and Nickel manganite (NiMn2O4) nanoceramic powder thermistor as a temperature sensor fabrication, characterization, calibration, and testing. The NiMn2O4 nanoceramic powder is synthesized using the wet chemical method and the ITO nanopowder-based heater is fabricated by a simple fill and press method. The heater, temperature sensor, Atmega328 microcontroller with its software, stainless steel cylindrical tubes, and 3D-printed package are used to fabricate the device. The distance between the heater and the temperature sensor is set to 0.006 m and heat pulse duration is set to 240 s. The heater consumes 3.587W electric power. The temperature sensor can measure the soil temperature up to 50°C. The system is capable of measuring volumetric soil moisture content from 3% to 37% efficiently with a strong correlation coefficient of $ 0.997 $ 0.997 with respect to the standard. The test result shows that there is less than a 2.8% error which is the smallest among the category and the sensitivity of the sensor at volumetric soil moisture content $ ({{\theta_v}})= 0.28{\textrm{m}^3}{\textrm{m}^{ - 3}} $ ( θ v ) = 0.28 m 3 m − 3 becomes $ 3.14^\circ \textrm{C} $ 3.14 ∘ C per $ {\textrm{m}^3}{\textrm{m}^{ - 3}} $ m 3 m − 3 . The developed system is simple to fabricate and operate highly precise, low cost, low power and light in weight. [ABSTRACT FROM AUTHOR]

High-entropy thin films of Mn0.6Co0.6Ni0.6Mg0.6Cu0.6O4, Mn0.6Co0.6Ni0.6Mg0.6 Zn0.6O4, and Mn0.6Co0.6Ni0.6Cu0.6Zn0.6O4 (MCNMC, MCNMZ, and MCNCZ) with equiatomic proportions were synthesized using chemical solution deposition on silicon substrates. Structural analysis confirmed a consistent face-centered cubic spinel structure, while significant differences in surface morphology were observed. Quantification of the valence states of Mn ions revealed an inverse variation in the concentrations of Mn4+ and Mn2+ ions. The heightened infrared light absorption of the MCNMC thin film was assigned to Cu-induced Jahn-Teller distortion and highly polarized Mg-O bonds. All samples exhibited negative temperature coefficient behaviors in their electrical properties. Additionally, the MCNMC thin film demonstrated the lowest resistance due to its denser microstructure, close proximity of Mn3+/Mn4+ ion concentrations, and additional Cu+/Cu2+ ion pairs, enhancing small polaron hopping conductivity. In contrast, the MCNMZ thin film showed moderate resistance but boasted the highest thermal constant (B25/50) of 3768 K, attributed to its distinctive grain chain structure, facilitating carrier transport while introducing migration barriers.

A series of (La 1-x B x MnO 3) (LaB 6)-based composite films were prepared by a combined magnetron sputtering and ion implantation method, and their structure-function relationship have been investigated. After B3+ ion implantation, the as-sputtered LaMnO 3 films still have perovskite structure and good surface flatness. However, the substitution and doping of B ions play the role of resistance regulation, and the formation of the second phase LaB 6 reduces the resistivity of the film after ion implantation to a certain extent. The carrier concentration of the ion injected film will decrease from 1.33 × 1016 cm−3 to 1.80 × 1015 cm−3, while the resistivity value will a significant increase from 46 Ω cm to 381 Ω cm with slight variations in principle in thermal constant from 2229 to 2783 K. The secondary phase doping of (La 1-x B x MnO 3) (LaB 6)-based perovskite materials bring an innovative perspective to the design and application of electronic materials. [ABSTRACT FROM AUTHOR]

In recent years, core-shell structures have attracted much attention for their potential in tuning the functional properties of materials and have become an effective method for preparing high-performance materials. In this work, core-shell structured 0.1LaMnO 3 @0.9(Ba 0.5 Sr 0.5)TiO 3 nanoparticles were fabricated by sol-gel method and dense ceramics were prepared at different sintering temperatures. The phase composition, morphology, chemical state and electrical properties were systematically investigated. Structural analysis confirmed the formation of 0.1LaMnO 3 @0.9(Ba 0.5 Sr 0.5)TiO 3 core-shell nanostructures. The results show that the prepared samples exhibit typical negative temperature coefficient characteristics in the range of 50–1000 °C, which is derived from the effect of carrier pairs and oxygen vacancies on the electrical properties. This study provides new insights from structure to material into guiding the development and design of advanced thermistor materials for temperature sensing applications. [ABSTRACT FROM AUTHOR]

Thermocouples require Cold Junction Compensation (CJC) and are widely used temperature sensors. These thermocouple types have high nonlinearities and consequently a linearization technique using higher degree polynomial based on non-linear regression is proposed. A K-type thermocouple is linearized using its inverse mathematical model. The percentage nonlinearity of the thermocouple was reduced from 2.03% to 0.02% Full Scale Span (FSS) in a range of -100 to 1372 °C. Thermistors are used for CJC in thermocouples and are highly nonlinear. A constant current is passed through the thermistor, and the drop is measured by an Analog to Digital Converter. The inverse mathematical model obtained from experimental data is cascaded to linearize the thermistor output. The percentage nonlinearity of the thermistor was reduced from 84.63% to 0.27% FSS for a range of 0 to 120 °C in experiment. The linearized thermistor was used for CJC of the thermocouple. Maximum absolute error observed in the temperature measurement using Yokogawa calibrator and thermocouple along with CJC were 0.24 °C and 0.43 °C respectively. A remote data-logger was used to store measured data. Stored data could be viewed and used for further processing from any Internet of Things user interface. The proposed temperature measurement system was found to be smart and reliable. [ABSTRACT FROM AUTHOR]

Herein, the x Bi(Zn 0.5 Ti 0.5)O 3 -(1- x) (Ba 0.5 Sr 0.5)TiO 3 (x = 0.05, 0.10, 0.15, 0.20) novel negative temperature coefficient (NTC) ceramic materials were fabricated by solid-state method. X-ray diffraction revealed that x Bi(Zn 0·5 Ti 0.5)O 3 -(1- x) (Ba 0.5 Sr 0.5)TiO 3 successfully formed solid solution. The UV–vis diffuse spectra of the samples indicate that the band gap increases with the increasing Bi(Zn 0·5 Ti 0.5)O 3 content. The resistance temperature curve showed that with the increase of Bi(Zn 0·5 Ti 0.5)O 3 content, the resistivity ρ of the ceramics at 400 °C increased from 5.96 × 106 to 2.67 × 107 Ω cm, as well as an increase in the B 400/800 from 12374.6 to 13469.1 K. The enhanced resistivity is attributed to the increased band gap and reduced carrier pairs caused by the Bi(Zn 0.5 Ti 0.5)O 3 modification. The impedance data indicates that the conduction process is activated by thermal. The ceramic samples exhibit the excellent NTC characteristics over a range of 400 °C–1000 °C. Hence, the x Bi(Zn 0.5 Ti 0.5)O 3 -(1- x) (Ba 0.5 Sr 0.5)TiO 3 ceramics have the potential to become high temperature NTC ceramics that can operate in a wide temperature range. [ABSTRACT FROM AUTHOR]

A new material tetrakis-µ3- (methoxo)(methanol)-pentakis(acetylacetonate)(tricuprum (II), neodymium (III)) methanol (I) was synthesized as [Cu3Nd(AA)5(OCH3)4CH3OH] ∙ CH3OH, where HAA = H3C–C(O)–CH2–C(O)–CH3. Based on the data of elemental analysis and physical-chemical research methods, it was found that the obtained coordination complex (I) contains atoms of Copper (II) and Neodymium (III) in the ratio Cu:Nd = 3:1, and its composition corresponds to the gross formula: Cu3NdО16C31Н55. The measurement of electrical conductivity of the obtained material was performed in the compressed form. For the coordination complex (I), the number of valence electrons in one molecule was calculated to be 270; the mass of one molecule was calculated to be 163,65·10-20 кг; the total number of molecules in the volume of a cylindrical sample weighing 0.125 g and having volume of 17,74∙10-9 m3 was calculated to be 7,638·1013 молек.; and the total number of valence electrons as 20,6232·1015. In the temperature range of 303 – 423 K, the specific resistance of the compressed sample decreases from 2∙1012 to 5∙104 Ohm∙cm, which confirms that the isolated compound is a semiconductor with a band gap of 1,6125 еВ. The electrical conductivity properties of the coordination complex as a thermosensitive element were studied; for this purpose we used an experimental sample of compressed material with geometric dimensions of 1·10-3 m×0,5·10-3 m×0,5·10-3 m.

Synthesis of Ag2S from AgCl waste of argentometric titration with heating temperature variations as a temperature sensor has been done. This study aims to synthesize Ag2S and examine the effect of heating temperature on crystal quality and electrical characteristics as a temperature sensor based on the Negative Temperature Coefficient (NTC). Ag2S synthesis was carried out by precipitation in a water bath with various heating temperatures of 40°C, 60°C, and 80°C. The success of the synthesis was confirmed by X-Ray Diffraction (XRD) with a typical peak of 2θ from Ag2S standard at 29.07°, 31.60°, 36.97°, 37.81°, and the highest crystallinity was obtained at a heating temperature of 60°C. Meanwhile, UV-Vis Diffuse Reflectance Spectroscopy (DRS UV-Vis) showed a band gap corresponding to Ag2S (0.9-1.05 eV). Furthermore, the Ag2S powder was made into pellets and applied as a temperature sensor. Then the resistance value and the electrical characteristics of the resulting sensor were measured. The best resistance was obtained from Ag2S synthesized at a temperature of 60°C with constant (B) and sensitivity (α) values of 2974 K and −3.35%, respectively. This indicated that Ag2S had been successfully synthesized, and the best sensor quality was obtained from Ag2S heated at a temperature of 60°C.

Monitoring body temperature has the potential to evaluate physical conditions. The oral cavity has a large accessible volume and exhibits a temperature close to the deep body temperature; the wireless monitoring of intra-oral temperature is also possible. However, devices must be small enough to not interfere with tongue movement. Here, we fabricated a mouthguard (MG) thermometer that housed a telemeter, a thermistor, and a battery on the buccal side surface of the molar and premolar of the upper jaw. The devices were sealed between two layers of MG material for waterproofing. Sealing the devices induced a longer response time to temperature changes (from 3.2 to 12.2 s), but the quantitative characteristics did not change. Rapid changes in intra-oral temperature were successfully monitored when ingesting water of various temperatures by using the MG thermometer. Moreover, a high correlation between the difference in the intra-oral and water temperatures and the intra-oral temperature change was observed. In addition, stable wireless measurement was possible during 3 h in an office with the wearer engaged in normal activities. The effects of changes in ambient temperature and the wearing of face masks on intra-oral and skin temperatures were also investigated, where an effect of ambient temperature on skin temperature but not on intra-oral temperature was observed. These results suggest that wireless temperature monitoring in the oral cavity is feasible. [ABSTRACT FROM AUTHOR]

Uncooled microbolometer arrays incorporating vertically aligned carbon nanotube absorbers are increasingly being adopted in satellite instrumentation for monitoring the Earth's radiation budget. A key requirement for such microbolometers is a thermistor having high-temperature coefficient of resistance (TCR), low 1/f noise while surviving high-temperature carbon nanotube growth at 800 °C. In the present work, Pt thin-film thermistors are fabricated on SiNx/SiO2/Si substrates using DC magnetron sputtering. To achieve enhanced adhesion of the Pt thin film, an interlayer of AlOx is deposited on the substrate via reactive high-power impulse magnetron sputtering. To maximize the positive TCR, the Pt/AlOx is subjected to different annealing conditions by varying temperature, time, and gaseous environment. With an increase in the annealing temperature and duration, Pt/AlOx thin film exhibits an improvement in TCR. Microstructural and morphological investigations suggest that improvement in TCR is related to the recrystallization of Pt and the resulting increase in grain size. A relatively high TCR of 0.308%/°C (TCR of bulk Pt = 0.359%/°C) was obtained at an operational range of 20–50 °C when Pt was annealed at 800 °C for 1 h and 3 h in air and Ar, respectively. Deposition of Pt without an AlOx interlayer resulted in thin film blistering and delamination when annealed at 800 °C for 1 h in air. A Pt/AlOx thermistor with a TCR of 0.308%/°C, annealed at 800 °C for 3 h in Ar has the potential for use in microbolometers that must undergo high-temperature growth of vertically aligned carbon nanotube absorbers. [ABSTRACT FROM AUTHOR]

The formation of oxide semiconductor films of the (Mn,Co,Cu)3O4 type by radio frequency magnetron sputtering is presented. The conditions of deposition and subsequent heat treatment make it possible to obtain films with electrophysical characteristics close to those of the bulk ceramic materials used as a target for magnetron sputtering. Two variants of thermistor geometry were implemented. In the first case, the working layer of oxide semiconductor was deposited directly on the dielectric substrate (planar geometry), and in the second case on the layer with high electrical conductivity (Ni or Al) forming the inner electrode (layered geometry). The lower limit of the nominal resistance of the planar thermistor while maintaining high temperature nonlinearity is ~ 10 kΩ. The layered structure with the inner electrode makes it possible to reduce the lower limit of resistance up to ~ 50 Ω without losing the temperature nonlinearity of the thermistor. In addition, heat treatment above 450 °C or current self-heating with sufficient power output leads to the appearance of a pronounced voltage nonlinearity, which increases the thermal constant B of thermistors from 2400–3400 to 5000–5500 K. The fields of application of oxide-film structures for the correction of linear resistors and the implementation of integration approaches in the construction of linearized sensors are discussed. [ABSTRACT FROM AUTHOR]

Body temperature is an important indicator of human health detection which can reflect the key information of human life activities. The real-time and accurate monitoring of skin temperature can reflect the health status of the human body for timely intervention and treatment which plays an important role in daily protection and clinical medicine. Conventional contact thermometers are easily to be misplaced during measurement due to poor fit with skin which affects normal human activities. The infrared thermometers without directly contacting the skin can measure the temperature fast but due to the easy shift of the infrared head in the measurement process the skin radiation level and the environmental factors will affect its measurement accuracy. The paper or film-based temperature sensors are flexible and lowly breathable so they are not suitable for dynamic measurement of human body temperature or real-time monitoring of single point skin temperature. Temperature sensing yarns combine a hybrid electronic yarn with microscopic sensing elements and flexible textile fibers which endow them with good feel and comfort to measure single point skin temperature and dynamic human body temperature. In order to know well the development status and trend of temperature sensing yarns and promote their industrial application we firstly analyzed the sensing characteristics of typical temperature sensing yarns i. e. thermoelectric temperature sensing yarns optical fiber temperature sensing yarns and thermal resistance temperature sensing yarns. Among them four methods for preparing thermistor sensing yarns were mainly introduced hybrid spinning filament dipping coating of textiles flexible printing electronics and flexible hybrid electronics. Then we summarized the characterization parameters and influencing factors of these temperature sensing yarns in terms of sensing properties and working performance. In the end we presented the technical challenges and shortcomings of temperature sensing yarns in industrialization and application. It is found that thermoelectric temperature sensing yarns can generate electricity according to the temperature difference between human body and cold environment but the compensation problem of cold end needs to be solved. Optical fiber temperature sensors with high measurement accuracy and anti-electromagnetic interference are settable. Thus they can be used as yarns to manufacture smart textiles. However they are easily broken under mechanical stress in service. Thermal resistance sensing yarns are difficult to locate and their accuracy is easily affected by the surrounding humidity or sweat so further improvement is needed for long-term local temperature measurement on human body. Thermistor sensing yarns are suitable for the medical field because of high sensitivity but they have poor durability and washing ability. At present there is no in-depth study on the mode and mechanism of yarn function failure and no systematic design principle to guide large-scale production. Temperature sensing yarns which boast the advantages of softness comfort and invisibility are suitable for smart textiles to measure human temperature such as socks for predicting early diabetic foot ulcers clothing and bedding for continuous temperature measurement of infants bandage for monitoring wound infection and so on. The summarized characteristics of various temperature sensing yarns provide suggestions for the evaluation criteria structure optimization and functional failure theories of sensing yarns as well as the future application and selection of smart textiles. [ABSTRACT FROM AUTHOR]

The solid-state reaction technique was used to prepare the sample 0.5(BiLayFe1–yO3)–0.5(PbZrO3) at different concentrations y = 0.05, 0.10, 0.15, 0.20. Structural parameters such as percent crystallinity, average crystallite size, dislocation density and microstrain were calculated from the X-ray diffraction data at room temperature. The scanning electron microscope micrographs reveal the spherical, densely packed natures of the samples with low porosity. The energy density with efficiency of the prepared samples was calculated from P–E loop. The performance of the composites as an NTC thermistor at high temperatures (275–400°C) was discussed. Thermistor constant, sensitivity index and activation energies were calculated to understand the characteristics of the NTC thermistor. The high value of density of states was determined from the frequency and temperature-dependent ac conductivity of the composites. [ABSTRACT FROM AUTHOR]

In this paper, a wide-range high-precision sensor has been designed in order to accurately measure the temperature in a medium with arbitrary temperature variation and the implementation of a wide-spectrum temperature measurement system with a self-selected multi-sensor has been realized. This multi-sensor core is made up of different sensors combined to measure different temperature ranges. This concept can be used for high-precision temperature measurement in electrical capacitance tomography applications. The proposed technique is well suited for temperatures in boilers, industries, and everywhere high temperature measurement sensitivity is needed by using different combined temperature sensors of high precision. [ABSTRACT FROM AUTHOR]

• An improved conventional time constant model for temperature sensors is proposed. • Model with thermistor wires outperforms conventional time constant model. • Method derived to calculate transient heat transfer through the wires. • Incorporating heat transfer through wires results in more accurate model fits. • Sensors and gaseous medium ensure a Biot number less than 1 (Bi < 0.1). A mathematical model incorporating the transient response of NTC thermistors is presented. The internal thermal conduction resistance of the sensor relative to the thermal convection resistance of the medium results in a low Biot number B i < 0.1 , yielding a fast dynamic response in gaseous media. This is advantageous in applications requiring minimal fluid interaction. However, negligible energy exchanges occur, introducing measurement uncertainty and ignoring the behavior of the measuring instrument. Therefore, this work proposes an improvement strategy for the mathematical model of these sensors, complementing the conventional model based on the concept of time constant. The strategy considers the heat flow through the thermistor wires in the energy balance, assuming they are semi-infinite solids and applying an approximation to the heat flow formula. Satisfactory improvement results were obtained compared to the conventional model, based on controlled laboratory tests with various gases. [ABSTRACT FROM AUTHOR]

Memristors were first proposed in 1971 by Leon Chua. These devices are usually regarded as being one of the newest fundamental breakthrough for electronics. Their role in designing new electronic systems is expected to be an important, key-factor. As an example, they already come in many forms: PCA, ReRAM, etc., to mention a few. In any case, since actual memristors have only appeared quite recently, this technology has yet to be mature enough to provide with readily available, off-the-shelf components. This implies that developing and testing new concepts or design architectures based on memristors are performed mainly by the use of numerical simulation. In this paper, we discuss a powerful modeling framework that eases creating and implementing new memristor models, illustrating with some examples of use.

This paper develops a simple, cost-effective, fully Inkjet-printed flexible temperature sensor with easy fabrication steps using PiXDRO LP50 inkjet printer. The thermistor sensor employed a Poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT: PSS) as a temperature-sensitive layer with silver nanoparticles (AgNps) as a contact electrode. The sensor performance was evaluated on different dimensions and types of substrates. Epson Glossy paper with 255 $\mu \text{m}$ thickness and Polyimide (Kapton HN) with $50~\mu \text{m}$ thickness were used over temperatures ranging from room temperature up to 50 °C and 90 °C for paper and Kapton substrates, respectively. The sensor developed over Glossy paper showed the best sensitivity of −1.67 %/°C in the chosen temperature range while the sensor showed +0.113%/°C on PI substrate.

We report the effect of incorporating graphene oxide in ZnS and developed a ZnS-RGO hybrid film with negative temperature coefficient (NTC) for thermistor application towards temperature sensing in this study. The light sensing properties of the films were also investigated by exposing the film to light sources from mercury and tungsten lamp and recording the photo resistance. As the composition of ZnS in ZnS-RGO increased, sharper diffraction peaks were observed thus confirming improved crystallinity. The crystallite size of ZnS-RGO hybrid decreased from 4.02 to 1.87 nm while the lattice strain increased from 0.0086 to 0.0185 as the composition of ZnS in the hybrid increased. ZnS-RGO recorded a maximum sensor response of 1.91 which is approximately twice the maximum value obtained for pure ZnS in literature. The negative temperature coefficient (NTC) for ZnS-RGO (0.00174825/K) was higher than values obtained in literature for ZnS and Ag nanoparticles coated RGO. Furthermore, the sensitivity value of ZnS-RGO (0.00769 Ω/ K) was five times that of ZnS while the activation energy (0.0352 eV) was about seven times the value reported for ZnS. The increase in activation energy of ZnS-RGO compared to ZnS is responsible for the improved sensing response of the hybrid while the intercalation of ZnS in GO created reactive sites that resulted in activation energy, sensing response and an NTC much higher than in pure ZnS thus favoring utilization of ZnS-RGO as thermistors. This research has shown that ZnS, intercalated in the matrix of GO improved the thermal and photo sensing properties of ZnS and is thus suitable in thermistor applications. These properties can be used to suggest the application of ZnS-RGO in optoelectronic applications such as EM detectors, solar cells and temperature monitoring devices.

Objective: Early diagnosis of obstructive sleep apnea (OSA) in children is important. The use of a nasal cannula as an airflow sensor during polysomnography has not been evaluated in younger children. The study aims to evaluate the use of nasal cannula in detecting respiratory events in children under three with suspected OSA during daytime nap studies.Methods: A total of 185 patients were prospectively included. Respiratory events were scored using nasal cannula alone, thermistor alone, and both methods simultaneously as the airflow sensor. Agreement and diagnostic accuracy were assessed.Results: One hundred and seventy-two children were finally analyzed and 110 (64.0%) presented OSA. Total sleep time with an uninterpretable signal was longer with the nasal cannula than with the thermistor (17.8% vs 1.9%; p < 0.001), and was associated with poor sensor tolerance and adenotonsillar hypertrophy. In the estimation of the apnea-hypopnea index, the nasal cannula showed lower agreement than the thermistor with the joint use of the two sensors (intraclass correlation coefficient: 0.79 vs 0.996 with thermistor). Compared with the thermistor, the nasal cannula presented lower sensitivity for detecting OSA (82.7% vs 95.5%) and a lower negative predictive value (76.5% vs 92.4%). Overall, fewer children were diagnosed with severe OSA with the nasal cannula (19.8% vs 30.8% with the thermistor, and 32.6% with both).Conclusions: In children under the age of three, the ability of the nasal cannula to detect obstructive events was relatively low. Therefore, other non-invasive measurements for identifying respiratory events during sleep may be of additional value. [ABSTRACT FROM AUTHOR]

In this article, an ultrathin and flexible thermal perception (FTP) sensor with a fingerprint-like sensing structure is proposed. The developed FTP sensor features a sandwich structure formed by biocompatible polyimide (PI), gold thermistors, and Parylene C layers with a total thickness of $8~\mu \text{m}$. Meanwhile, multisensory functions including temperature and pressure sensing, as well as matter recognition are realized. Specifically, the FTP sensor shows an ultrafast response time of less than 0.12 s and 52 ms for matter and temperature detection, respectively, while various matters information such as PI, rubber, and steel, can be easily distinguished. Besides, the ultrathin design allows the sensor to gain signal stability of less than 0.3% even at a curvature up to 0.25 mm−1. Furthermore, the FTP sensor achieved a sensitivity of 812 mV/kPa for pressure sensing after being partially covered with a thermal conductive powder-doped silicone film. In short, the demonstrated functionality of this ultrathin FTP sensor combined with its simple fabrication holds the prospect of further advancing and deploying this device as a promising sensory system for mimicking human interaction. [ABSTRACT FROM AUTHOR]

A thermistor is connected to the induction coil in series of the Chua circuit and a thermosensitive oscillator is obtained by applying scale transformation on the physical variables and parameters in the circuit equations. The dynamics dependence on temperature and synchronization stability under field coupling are discussed in detail. The sole Hamilton energy for each thermosensitive oscillator is calculated, and energy pumping along the coupling channel is continued before reaching complete synchronization between two thermosensitive circuits. The energy propagation in the coupling channel is controlled by the physical property of electric components such as capacitor and inductor. The magnetic field energy (or electric field energy) is pumped across the coupling channel when induction coil (or capacitor) is used to activate field coupling between chaotic circuits. Within this work, capacitor, and induction coil are respectively used to synchronize two thermosensitive circuits and the energy balance is also controlled. When two identical thermosensitive oscillators are controlled adaptively to reach complete synchronization, the energy balance is also realized. Furthermore, the temperature parameter is changed to detect the synchronization stability, and energy pumping along the coupling components in the coupling channel is estimated for detecting complete synchronization approach. Analog circuit implement is verified via Multisim and synchronization realization is detected as well. The advantage of this coupling scheme is that energy is pumped rather than consuming the Joule heat in the coupling channel before reaching complete synchronization, and the coupling channel can also be controlled by external physical field. The involvement of thermistor makes the chaotic systems become sensitive to the temperature, while the coupling scheme still works well and energy balance is controlled for reaching complete synchronization. Finally, a section for exploring open problems is supplied to guide the realization of adaptive synchronization control and energy balance for other nonlinear systems and neural circuits. [ABSTRACT FROM AUTHOR]

Carbon-rich SiCN ceramics were prepared by divinylbenzene (DVB)-modified polysilazane (PSN2), and a high-conductivity SiCN thin film sensor suitable for medium-low temperature sensing was fabricated. The modified liquid precursors were patterned by direct ink writing to produce SiCN resistive grids with line widths of several hundreds of micrometers and thicknesses of several micrometers. The introduction of DVB not only increases the critical thickness of SiCN ceramics several times, but also significantly improves the conductivity of SiCN, making it meet the conductivity requirements of sensing applications in the mid-low temperature range. The electrical conductivity and microstructure of DVB-modified SiCN ceramics were studied in detail. In the temperature range of 30~400 °C, the temperature resistance performance of DVB modified SiCN resistance grid was measured. The SiCN ceramics with low DVB content not only have excellent electrical conductivity, but also have good oxidation resistance. [ABSTRACT FROM AUTHOR]