High-precision Temperature Sensor Research Articles

Robustly packaged lithium niobate resonator-based temperature sensor

Abstract Whispering gallery mode (WGM) resonators with high optical quality factor (Q) are highly sensitive to environment changes and are used in various sensing applications. We have developed a high-precision temperature sensor using a compactly packaged lithium niobate (LN) WGM resonator. This sensor offers a sensitivity of 34.38pm/℃ and a high resolution of up to 5.6×10-4 ℃. It is portable with high Q, making it suitable for using outside the laboratory. The device is also resilient to changes in humidity, enhancing its practicality.

Implementation of Wearable Wireless Chest Patch Monitoring Terminal

A wearable wireless chest patch monitoring terminal is designed to realize the acquisition, processing, and wireless transmission of ECG, respiration, and body temperature signals. The analog front-end ADS1292R, which integrates respiratory impedance and ECG front-end, is utilized to collect human ECG and respiratory signals. The body temperature is collected using a low-power, high-precision digital temperature sensor MAX30208. A filter algorithm for signal processing and wireless transmission is designed through a low-power nRF52840 Bluetooth SoC with an Arm Cortex-M4F kernel. The experimental results show that the designed monitoring terminal can monitor the ECG, respiration, and body temperature parameters of the human body in real-time and send the monitoring results via Bluetooth, with a continuous working time of more than 13 hours. The wearable wireless chest patch monitoring terminal features good portability, long standby time, and high measurement accuracy, and it has promising application prospects in the fields of family health monitoring, mobile medical treatment, and smart healthcare.

Research on a smart bra design strategy and platform for breast health risk monitoring

To reduce the risk of breast disease in women, we proposed a new smart bra design scheme. We implanted high-precision temperature sensors into the bra for real-time data monitoring, and used multipoint comparison technology to obtain early warnings of breast lesions based on abnormal temperature data. The proposed monitoring system can perform functions such as real-time data feedback, periodic report recording, remote consultation, health management, and electronic medical record generation. Compared with previous approaches, the functionality of this smart bra is not affected by dynamic body movements or environmental temperature, and its monitoring range for breast diseases is wider. This study promotes the monitoring and prevention of breast diseases in women, leading to a shift from disease treatment to disease prevention.

Experimental and numerical investigation of the temperature and humidity distribution inside the channels for a regenerative indirect evaporative cooler

This paper presents a simulation study of a regenerative indirect evaporative cooler combined with a series of experimental tests. A research prototype was employed to collect the air state signals in the channels with built-in high-precision temperature and humidity sensors on a test platform which helped to maintain the required environment. A validated numerical model was developed to simulate the impacts of air velocity, working air ratio and testing environment parameter on the distribution of temperature and relative humidity inside the channels. Results show that the upstream of the secondary air approaches saturation rapidly, and the evaporation process reaches dynamic equilibrium when the relative humidity of the secondary air comes to 95%. Under most working conditions, a 400 mm wet pathway can meet the performance requirements for an evaporative cooler. The low velocity allows a shorter distance for the secondary air to approach saturation while the lower product air temperature can be obtained. The working air ratio has little impact on the temperature and humid parameters. When the temperature difference between the primary air and the secondary air is higher than 5 °C, the potential for sensible heat exchange becomes more significant. In the dry environment, the regenerative indirect evaporative cooler should reserve a longer wet surface length, and high temperature difference exist between primary air and secondary air. The sensible heat transfer needs to be strengthened to fully utilize the potential of evaporative cooler.

Design of High Precision Temperature Sensor with Current Gain Compensation Technology for On-Chip Application

The integration of on-chip temperature sensors within various systems, industrial Internet of Things (IoT), and wireless sensor networks is greatly facilitated by their small size, cost-effectiveness, and capability to provide direct digital output. However, the diverse application scenarios pose challenges in designing these sensors. On one hand, real-time clock calibration demands high-precision temperature sensors, while on-chip heat management emphasizes compactness and low-voltage operation. Additionally, streamlining the calibration cost for mass production holds significant practical value. Addressing these challenges, this study systematically investigates on-chip complementary metal-oxide-semiconductor (CMOS) temperature sensors based on distinct signal domains processed by temperature readout circuits. Specifically, the research commences by analyzing the issues of several degeneracy points in the front-end circuit of a bipolar junction transistor (BJT) temperature sensor with current gain compensation technology. To address the intricate design challenges in advanced technologies and calibration complexities in industrial applications, dynamic component matching, current gain compensation, and chopper stabilization are harnessed. A novel dynamic current gain canceling technique for temperature readout is introduced, enhancing temperature measurement accuracy without incurring additional power consumption or area overhead. Ultimately, an all-digital CMOS temperature sensor is realized using the SMIC 55 nm CMOS process. Occupying a mere 0.29 mm2 of core area, the design operates efficiently across a wide supply voltage range of 1.2 V to 3.6 V. Covering a temperature spectrum from −40 °C to 125 °C, the sensor demonstrates a calibration error of just ±0.7 °C. This achievement is attributed to the incorporation of the proposed dynamic current gain compensation technique.

Data monitoring for indirect metering terminal of membrane gas measure device based on sensor network

In order to improve the data monitoring and information management capabilities of membrane gas measure device indirect metering terminals, a sensor network based data monitoring method for membrane gas measure device indirect metering terminals was proposed. The distributed and centralized sensor network node deployment method is used to achieve data collection for membrane gas measure device indirect metering terminals, and the collected membrane gas measure device indirect metering terminal data is segmented, fused, and reorganized. The distributed energy storage and constant volume two-level optimal control method is used to analyze the operation status of gas measure device indirect metering terminal data. The ZigBee networking protocol is used to build a network structure model for gas measure device indirect metering terminals, an integrated high-precision temperature and pressure sensor arranged parallel to the inner wall of the valve body is used to detect the temperature and pressure at the outlet of the membrane gas measure device. The temperature information is stored in DSP, and the user's expenses, system operation and maintenance, and peak shaving and valley filling benefits are taken as the parameters of the energy storage and constant volume outer layer model. The output stability of the indirect metering terminal data of the membrane gas measure device is analyzed in the high switching frequency mode. Combined with adaptive parameter adjustment, the indirect metering terminal control and data dynamic collection of the membrane gas measure device are realized. Realize dynamic monitoring of metering terminal data in wireless sensor network networking control mode. The test results show that using this method for indirect metering terminal data monitoring of gas measure devices has good output stability, strong dynamic fusion of sensing information, reduced metering errors, and improved metering accuracy of gas measure devices.

Temperature sensing with RF-dressed states of nitrogen-vacancy centers in diamond

Using the electronic spin of nitrogen-vacancy (NV) centers in diamond is a promising approach to realizing high-precision temperature sensors; furthermore, pulsed optically detected magnetic resonance (pulsed-ODMR) is one way to measure the temperature using these NV centers. However, pulsed-ODMR techniques such as D-Ramsey, thermal echo, or thermal Carr–Purcell–Meiboom–Gill sequences require careful calibration and strict time synchronization to control the microwave (MW) pulses, which complicates their applicability. Continuous-wave ODMR (CW-ODMR) is a more advantageous way to measure temperature with NV centers because it can be implemented simply by continuous application of a green laser and MW radiation. However, CW-ODMR has lower sensitivity than pulsed-ODMR. Therefore, it is important to improve the temperature sensitivity of CW-ODMR techniques. Herein, we thus propose and demonstrate a method for measuring temperature using CW-ODMR with a quantum spin state dressed by a radio-frequency (RF) field under a transverse magnetic field. The use of an RF field is expected to suppress the inhomogeneous broadening resulting from strain and/or electric-field variations. The experimental results confirm that the linewidth is decreased in the proposed scheme when compared to the conventional scheme. In addition, we measured the temperature sensitivity to be about 50.4±3.5mK/Hz, and this is approximately eight times better than that of the conventional scheme.

Model-Based Approach to Long Term Prediction of Battery Surface Temperature

Temperature has a substantial impact on the safety, efficiency, and reliability of a lithium-ion (Li-ion) battery. The objective of a battery thermal management system (BTMS) is to maintain the battery in preferred temperature range. State-of-the-art BTMS is designed to react to the measured temperature at the battery surface, whereas research suggests that the performance of BTMS will likely improve when used in conjunction with predicted temperature. This article focuses on surface temperature prediction of Li-ion batteries based on an equivalent circuit model-based approach. Particularly, this article presents theoretically sound approaches to model heat generation in the core of the battery and its propagation to its surface. Another novel aspect of the present article is that the heat generation and propagation model identification is tested in various practical scenarios, where the measurement noise is significant. Experimental results using data collected from high precision battery cycler and temperature sensor show an open-loop mean absolute error of 1.678 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> C during a high-current discharge that lasted approximately 800 s. Using the theoretical models presented in this article, the performance battery temperature prediction error at low SNR conditions can be understood.

Sagnac Interferometric Temperature Sensor Based on Boron-Doped Polarization-Maintaining Photonic Crystal Fibers

A sensitive temperature sensor was demonstrated using boron-doped polarization-maintaining photonic crystal fiber (PM-PCF) as a Sagnac interferometer (SI). This boron-doped PM-PCF combines both the geometric birefringence introduced by the PCF structure design and the stress birefringence introduced by the boron-doped stress-applying parts. However, we found that the stress birefringence dominates the total birefringence of the sensor by numerical analysis. In the experiments, the fabricated sensor exhibited the highest temperature sensitivity of −1.83 nm/°C within the wide temperature range of 28~76 °C. The temperature sensitivity was mainly derived from the stress birefringence of boron-doped PM-PCF SI. These findings provide some support for the designation of high-precision temperature sensors.

Numerical and experimental study on temperature measurement performance of SNS fiber optic sensor with liquid-sealed

Single-mode-no-core-single-mode (SNS) optical fiber structures have valuable potential to encapsulate as high-precision temperature sensors, due to their great sensitivity. This paper is to improve the temperature sensitivity of SNS fibers by studying the parameters of fiber length, diameter, and refractive index of the seal liquid. Transmission spectra of the fibers are given in both aspects of experiment and numerical simulation. We find that using a slim no-core fiber section sealed with liquid of high refractive index can effectively improve the sensitivity, while the choice of fiber length mainly affects the width of transmission peak. The results may contribute to the development of high-sensitivity optic temperature sensor.

A non-invasive and high precision sensor for in-situ temperature monitoring of cells

Energy transformation, which can be described as temperature variations, is present in all activities of cellular metabolism. Detecting the temperature of numerous cells over the course of their lives is useful for studying the cellular physiological function and investigating the pathophysiology of illnesses. Current cell thermometric technologies, such as luminous temperature sensors, infrared thermometers, and thermocouple thermometers, have their own limitations, such as complicated operation, low repeatability, and inability to measure cell temperature in normal situations. Here, we have developed a high-precision platinum temperature sensor with small heat capacity, good heat conduction, excellent stability and biological compatibility, which made it possible to sense cells heat signal. The platinum resistance sensor’s temperature coefficient of resistance was around 2800 ppm °C−1, with a good linear correlation (R 2 > 0.999) between resistance and temperature from 35 °C to 43 °C. The noise of the sensor system was below 0.02 °C, giving a small and stability noise in detection. The detecting cells were CHO-K1 cells. They caused a temperature increase of about 0.075 °C, which is higher than the sensor without cells. This platinum sensor has been found to be useful for in situ temperature measurement of cells, which is important for investigating cell informatics and pathology.

High-precision fiber-optic temperature sensor based on Fabry-Perot interferometer with reflective thin-film multilayer structures

An embodiment of a fiber-optic temperature sensor based on a Fabry-Perot interferometer and a scheme for interrogating an experimental sample of the sensor are proposed. The proposed solution makes it possible not to use expensive spectral measuring devices (spectrum analyzer, interrogator). The region of free dispersion and the phase sensitivity of the developed Fabry-Perot interferometer were determined in the temperature range from 20 °C to 590 °C. The accuracy of measuring the ambient temperature is calculated. The long-term stability of the measuring setup at room temperature has been evaluated. The phase shift of the Fabry-Perot interferometer with temperature change was registered. The design of the Fabry-Perot interferometer is implemented using reflective thin-film multilayer structures obtained by stage-by-stage electron-beam deposition in vacuum on polished end cleavages of an optical fiber. The interferometer interrogation method is based on the use of a vertical-cavity surface-emitting laser (VCSEL) operating in a pulsed mode. The principle of registering the phase shift of the interferometer with a change in temperature is based on the use of auxiliary modulation of laser radiation along the wavelength due to modulation (periodic change) of the duration of optical pulses. Auxiliary modulation makes it possible to obtain additional harmonic components in the interferometer signal, which are further used in homodyne demodulation to restore the interferometer phase shift signal proportional to the change in the optical path difference between the interferometer mirrors. The design of the high-temperature sensor is based on a Fabry-Perot interferometer the reflecting mirrors of which are five alternating layers of thin films of TiO2 and Al2O3. Based on the results of the temperature experiment, it was concluded that an increase in the ambient temperature leads to a decrease in the free dispersion region of the Fabry-Perot interferometer. The conclusion made is consistent with the theoretical data. According to the results of the experiment, it is shown that the phase sensitivity of the interferometer to temperature changes is 0.94 rad/K. The accuracy of temperature measurements at the 3σ level was 0.017 K. The results of the study may be of great importance in creating systems for monitoring temperatures above 300 °C. The use of such an interferometer makes it possible to carry out high-precision relative temperature measurements.

High-sensitivity self-powered temperature/pressure sensor based on flexible Bi-Te thermoelectric film and porous microconed elastomer

• A self-powered Bi-Te and porous microcone-based temperature/pressure sensor is presented. • A flexible TEG could harvest body heat to power pressure sensor and sense temperature. • Bi-Te based TE thin film with heat sink achieves a high-precision temperature sensor. • The porous microconed architectures greatly enhance the sensitivity of pressure sensor. Electronic skins are artificial skin-type multifunctional sensors, which hold great potentials in intelligent robotics, limb prostheses and human health monitoring. However, it is a great challenge to independently and accurately read various physical signals without power supplies. Here, a self-powered flexible temperature-pressure bimodal sensor based on high-performance thermoelectric films and porous microconed conductive elastic materials is presented. Through introducing flexible heat-sink design and harvesting body heat energy, the thin-film thermoelectric device could not only precisely sense temperature signal but also drive the pressure sensor for detecting external tactile stimulus. The integration of Bi-Te based thermoelectric film with high stability in wide temperature range enables the sensor to sense the ambient temperature with high resolution (<0.1 K) as well as excellent sensitivity (3.77 mV K –1 ). Meanwhile, the porous microconed elastomer responds to pressure variation with low-pressure detection (16 Pa) and a high sensitivity of 37 kPa –1 . Furthermore, the bimodal sensor could accurately and simultaneously monitor human wrist pulse and body temperature in real time, which demonstrates promising applications in self-powered electronic skins for human health monitoring systems.

A Low-Power Passive UHF Tag With High-Precision Temperature Sensor for Human Body Application

Radio frequency identification (RFID) tags are widely used in various electronic devices due to their low cost, simple structure, and convenient data reading. This topic aims to study the key technologies of ultra-high frequency (UHF) RFID tags and high-precision temperature sensors, and how to reduce the power consumption of the temperature sensor and the overall circuits while maintaining minimal loss of performance. Combined with the biomedicine, an innovative high-precision human UHF RFID chip for body temperature monitoring is designed. In this study, a ring oscillator whose output frequency is linearly related to temperature is designed and proposed as a temperature-sensing circuit by innovatively combining auxiliary calibration technology. Then, a binary counter is used to count the pulses, and the temperature is ultimately calculated. We designed a relaxation oscillator independent of voltage and current. The various types of resistors were used to offset the temperature deviation. A current mirror array calibration circuit is used to calibrate the process angle deviation of the clock circuit with a self-calibration algorithm. This study mainly contributes to reducing power consumption and improving accuracy. The total power consumption of the RF/analog front-end and temperature sensor is 7.65 &#x03BC;W. The measurement error of the temperature sensor in the range of 0&#x2013;60 &#x00B0;C is less than &#x00B1;0.1%, and the accuracy of the output frequency of the clock circuit is &#x00B1;2.5%.

High-Precision Optical Fiber Temperature and Pressure Sensor and Its Application in Production Wells

High-Precision Optical Fiber Temperature and Pressure Sensor and Its Application in Production Wells

Design and Analysis of High-Precision Weighted Linear Least-Squares Fitting Algorithm for Fluorescent Optical Fiber Temperature Sensor

Microwave hyperthermia is a new method of treating cancer, where the therapeutic effect is determined by the heating temperature. Traditional active temperature sensors are interfered by high frequency so that the accuracy of temperature measurement cannot be guaranteed. It is of great significance to study the high-precision fluorescent optical fiber temperature sensor with complete insulation. This paper has realized a compact and practical fluorescent optical fiber temperature sensor after studying the optical path, circuit, data processing algorithm. In order to improve the accuracy of the system, the weighted linear least-squares fitting algorithm is improved in this paper. Through experimental tests, compared with the standard linear least-squares fitting algorithm and the unimproved weighted linear least-squares fitting algorithm, the accuracy of the algorithm is improved by about 98% and 65.5%, respectively. In addition, the response time is reduced by about 36.5%, compared with the unimproved weighted linear least-squares fitting algorithm. This algorithm fully meets the precision requirements of microwave hyperthermia.

High-precision silicon-based integrated optical temperature sensor

The predecessor of China Optics was China Optics and Applied Optics Digest, which was founded in 1985. At that time, it was the only retrieval journal in the field of optics in China. At the end of 2008, China Optics and Applied Optics Digest was renamed

Design and Batch Microfabrication of a High Precision Conductivity and Temperature Sensor for Marine Measurement

Precise meshing and three-dimensional monitoring of the marine environment are very important for marine resources exploration, fishery development, and military activities. Therefore, a high-precision, low power consumption, low-cost and multiparameter integrated miniaturized sensor has been in a large-scale demand. Besides, conductivity and temperature are the basic dynamic parameters of the ocean. This paper presents a high-precision conductivity and temperature (CT) integrated sensor based on the micro-electro-mechanical system (MEMS) batch microfabrication technology, which has small size, low cost, high uniformity, and efficiency in meshing and three-dimensional marine measurements. In this study, the miniaturized CT sensor shows excellent linearity of conductivity ( ${R} ^{2} \ge0.99999$ ) and temperature ( ${R} ^{2} \ge 0.999$ ) measurements. The temperature sensitivity of the CT sensor is $0.0619~^{\circ }\text{C}/\Omega $ , and the cell constant of the CT sensor is 2.559 cm−1. The temperature test also shows the high repeatability with the variance coefficient of 0.6%. Furthermore, it shows an excellent consistency for batch. The coefficient of variance of cell constants is ±0.019 cm−1 and the 95% confidence intervals for the conductivity is demonstrated to be ±0.0048 mS/cm. The variance coefficient of the temperature sensor is only 1.8%. The results indicate that the batch microfabricated sensors are suitable for a large-scale deployment in the Marine Internet of Things.

A novel low-cost, high-precision sea temperature sensor for coral reef monitoring

The role of elevated sea temperatures in coral bleaching has been well documented. Many of the sea temperature records utilized for purposes of widespread, multi-species bleaching predictions in recent publications have been acquired through satellite remote sensing. Satellites estimate sea temperatures at only a narrow range of depths near the surface of the ocean and may therefore not adequately represent the true temperatures endured by the world's coral ecosystems. To better characterize sea temperature regimes that coral reef ecosystems experience, as well as better define the individual thresholds for each species that bleaches, in situ sea temperature sensors are required. Commercial sensors are expensive in large quantities, however, reducing the capacity to conduct large- scale research programs to elucidate the range of significant scales of temperature variability. At the National Oceanic and Atmospheric Administration's (NOAA) Atlantic Oceanographic and Meteorological Laboratory (AOML), we designed a low-cost (roughly US$9 in parts) and high- precision sea temperature sensor that uses an Arduino microprocessor board and a high accuracy thermistor. This new temperature sensor autonomously records temperatures onto a memory chip and provides better accuracy (+0.05 °C) than a comparable commercial sensor (+0.2 °C). Moreover, it is not difficult to build; anyone who knows how to solder can build the temperature sensor. In March 2019, students at middle and high schools in Broward County, Florida, built close to 60 temperature sensors. During 2019, these sensors will be deployed by Reef Check, a global-scale coral reef monitoring organization, as well as by other programs to determine worldwide sea temperature regimes through the Opuhala Project (https://www. coral. noaa. gov/opuhala). This paper chronicles results from the initial proof-of-concept deployments for these AOML-designed sensors.

Study on a High Performance MEMS Infrared Thermopile Detector.

This paper presents a high-performance micro-electromechanical systems (MEMS) thermopile infrared detector. It consists of a double-end beam and a dual-layer thermocouple structure, which improves the responsivity of the detector. The etch-stop structure is integrated into the detector to prevent isotropic etching-caused damage on the device. The responsivity of the detector achieved 1151.14 V/W, and the measured response time was 14.46 ms. The detector had the potential to work as a high-precision temperature sensor and as a vacuum sensor.