Simultaneous Measurement Of Temperature Research Articles

Simultaneous Vibration and Temperature Real-Time Monitoring Using Single Fiber Bragg Grating and Free Space Optics

Simultaneous monitoring of temperature and vibration of electromechanical systems, public buildings, and volcanic terrain is an important indicator of preventing accidents. This work showcases the simultaneous temperature and vibration measurement using a single-fiber Bragg grating (FBG) sensor. The concurrent interrogation of vibration and temperature by the FBG sensing system can be integrated with free space optics (FSO), which saves on the costs associated with fiber optic cables and overcomes terrain barriers. Furthermore, the real-time measured vibration frequencies and different temperature levels can be recognized by a deep neural network (DNN) sequential model. In addition to the FSO support, the sensing system can be arranged in multiple sensing locations to form a wide range of measurements, offering a highly cost-effective solution.

A curvature and temperature simultaneous measurement sensor based on micro-taper Formed MZI and an Embedded FBG

Abstract A compact fiber Bragg grating (FBG) and Mach–Zehnder interferometer (MZI) compound for simultaneous measurement of bending and temperature is described. The FBG and MZI are fabricated in fiber forming a compact device, which is different from the previously developed axial cascade of different structures. Experimental results show that the FBG and MZI have different sensitivities for bending and temperature, allowing this device to measure bending and temperature simultaneously. The device has the advantages of small size, simple preparation steps, low cost, short preparation cycle, etc. Due to its excellent performance, it has the potential to become an excellent universal bending and temperature sensor.

Dual parametric simultaneous measurement of pH and temperature based on optical fiber interference and silanized pH-responsive hydrogel

A no-core and few-mode fiber-based structure coating with polyacrylic acid acrylamide hydrogel is used to realize pH and temperature measurement simultaneously. The proposed structure can be obtained through splicing the no-core fiber, few-mode fiber and no-core fiber (NFN) with a certain length in sequence. Its measurement range can cover 2 to 12 for pH and 20 °C to 90 °C for temperature. Meanwhile, surface silanization of the optical fiber is performed to facilitate the adhesion of the hydrogel and to refine the silanization process. The pH-based transmission-sensitivity is measured to be 0.959 dB/pH and the highest pH-based wavelength-sensitivity is 0.837 nm/pH. The temperature-based wavelength-sensitivities are measured to be 0.01 nm/°C and 0.02 nm/°C, respectively, in two different pH environments of 2 ∼ 5 and 5 ∼ 12, while the temperature-based transmission-sensitivities are measured to be 0.432 dB/°C and 0.356 dB/°C, respectively. The pH response of hydrogel and inherent temperature response of NFN-based Mach-Zehnder interferometer enable the sensor to perform dual parameter measurements for pH and temperature. The dual-parameter matrices are established and validation experiments are carried out. It is demonstrated that the pH and temperature measurement errors can be as low as 0.088 and 1.112°C respectively. This sensor is expected to have broad prospects in environmental monitoring, chemical analysis, and other related fields.

FDM-assisted OA-CEAS system for simultaneous measurements of temperature, CO2, and CO in flames

A system based on off-axis cavity enhanced absorption spectroscopy (OA-CEAS) integrated with frequency division multiplexing (FDM)-assisted wavelength modulation spectroscopy (WMS) was developed for simultaneous measurements of temperature, CO2, and CO in flames by employing two distributed feedback (DFB) diode lasers at 2.0 µm and 2.3 µm. An integrated cavity with an open-path configuration was made up of two cavity mirrors with a reflectivity of 99.8 %, and an effective optical absorption path length of approximately 5.2 m was achieved within a 6 cm diameter flame region. A CO2 line pair at 4990.418 cm−1 and 4990.664 cm−1, along with a CO line at 4300.699 cm−1, were selected as the measurement targets. The system was initially calibrated in a heated static cell and subsequently tested in C2H4/air premixed flat flames for six different equivalence ratios. All concentrations measured by the 1f-normalized 2f signals were compared with the results obtained from both the direct absorption signals and simulations based on adiabatic chemical equilibrium calculations using Chemkin. Additionally, the measured temperatures were compared with the thermocouple readings. According to the measurements conducted at representative C2H4 flames with different equivalence ratios, the accuracies for the measurements of temperature, CO2 concentrations, and CO concentrations were ∼1.062 %, ∼1.082 %, and ∼1.052 %, respectively. All the measurements illustrate the potential of the system for combustion diagnosis.

Simultaneous sensing of axial strain and temperature based on a sensitivity-selectable all-fiber Lyot-like filter

In this paper, an all-fiber Lyot-like filter with tunable free spectral range (FSR) and selectable sensitivity is proposed and experimentally demonstrated for simultaneous sensing of axial strain and temperature. Compared to the traditional fiber-based Lyot filter, the Lyot-like filter has an additional single-mode fiber (SMF) based polarization controller (PC), which is placed between two sections of polarization-maintaining fiber (PMF). In our experiment, the tunable FSR is achieved by adjusting the PC at a special angle, and a small FSR value of 6.58 nm and a large FSR value of 18.49 nm are obtained, respectively. Moreover, the experimental results show that the small FSR has low axial strain and temperature sensitivity, while that of the large FSR is high. By detecting the wavelength shifts of the filter spectra dip points, the simultaneous sensing of axial strain and temperature can be realized easily using a dual-parameter matrix. The proposed Lyot-like filter has the advantages of tunable FSR, selectable sensitivity, and simultaneous measurement of temperature and axial strain, which shows potential sensing applications in aerospace, chemical production, and bridge condition monitoring.

Bifunctional nanoprobe for simultaneous detection of intracellular reactive oxygen species and temperature in single cells.

Living cells can rapidly adjust their metabolic activities in response to external stimuli, leading to fluctuations in intracellular temperature and reactive oxygen species (ROS) levels. Monitoring these parameters is essential for understanding cellular metabolism, particularly during dynamic biological processes. In this study, we present a bifunctional nanoprobe capable of simultaneous measurement of ROS levels and temperature within single cells. The nanoprobe features two individually addressable nanoelectrodes, with platinum (Pt) and nickel (Ni) coatings on both sides. At the tip, these two metal layers form a nano-thermocouple, enabling precise intracellular temperature measurements, while the Pt layer facilitates selective ROS detection. This dual functionality allows for real-time monitoring of cellular responses during synergistic chemo-photothermal therapy of cancer cells and zebrafish embryos subjected to mitochondrial toxic stress. Our results demonstrate that the nanoprobe effectively measures increases in temperature and ROS levels in HeLa cells undergoing chemo-photothermal therapy, as well as in chemically stimulated zebrafish embryos. By providing detailed analysis of submicrometer-scale temperature and ROS variations within living cells, this nanoprobe offers valuable insights into cellular processes and holds promise for early disease detection and drug development.

Integrated hybrid optical fiber Mach-Zehnder interferometers for simultaneous measurement of seawater temperature and salinity

An integrated hybrid Mach-Zehnder (MZ) interferometer based on femtosecond laser micromachining for simultaneous measurement of seawater temperature and salinity was proposed. Two microcavities were machined on the multimode fiber (MMF) using a femtosecond laser to form a three-beams MZ interferometer and used to measure seawater temperature and salinity. The simulation results showed that the response of the sensor to temperature and salinity was only affected by the length of the microcavity, and the depth of the microcavity responded to the structural strength of the sensor. The experimental results showed that the temperature sensitivity of the sensor was 4.401 nm/℃ in the temperature range of 5 ∼ 40 ℃, and the salinity sensitivity was 0.784 nm/‰ in the salinity range of 3.52 ‰ ∼ 59.41 ‰. The sensor had the advantages of high sensitivity and integration, which was expected to be applied in the measurement of seawater multi-parameters.

Simultaneous measurement of liquid refractive index and temperature based on the birefringence response of a water-filled D-shaped photonic crystal fiber

In this paper, a water-filled D-shaped photonic crystal fiber (WFDSPCF) sensor based on the birefringence response for simultaneously measuring the liquid refractive index (LRI) and liquid temperature (LT) is proposed. We undertake theoretical and simulation calculations, and the results show that the proposed WFDSPCF can achieve ultrahigh LRI and LT sensitivities when operating around the group birefringence turning point. By optimizing the structural parameters, the proposed WFDSPCF sensor can achieve LRI and LT sensitivities of -25642.86 nm/RIU and 12.8 nm/°C, respectively. In addition, in order to eliminate the sensing crosstalk between the LRI and LT, a parallel Lyot interferometer structure is also proposed. The proposed WFDSPCF sensor is expected to have potential use in biochemical sensing, measurement science, and environmental monitoring.

Simultaneous measurement of temperature and refractive index based on fiber optic Fabry–Pérot cavity in batteries

Abstract A Fabry-Pérot (FP) sensor for simultaneous measurement of refractive index and temperature of an all-fiber synchronous liquid based on the Vernier effect is proposed, special application for internal monitoring of lithium-ion battery electrolytes. The theoretical model of high sensitivity cascade Fabry-Pérot interferometer (PFPI) is established, the sensitivity amplification mechanism of PFPI is analyzed in detail, the perfect matching scheme for measuring the refractive index of the electrolyte inside the battery is designed according to the matching conditions of the optical path, and the corresponding sensors for simultaneous measurement of the temperature and the refractive index are fabricated. The experimental results show that the sensor has a maximum refractive index sensitivity of 15391.5033 nm/RIU, a good linear fit, and can effectively monitor the refractive index change of the electrolyte by 10-4 orders of magnitude during normal charging and discharging of lithium-ion batteries. Compared to traditional epoxy adhesive bonded or laser processed FP sensors, this all-fibre optic structure not only improves temperature and corrosion resistance, but also significantly reduces temperature cross-sensitivity. Its small size and excellent resistance to high temperature and corrosion ensure the sensor's excellent response and broad application prospects in monitoring the refractive index of the electrolyte in 18650 lithium-ion batteries, which provides effective technical support for monitoring the health status of batteries and detecting early safety issues.

Simultaneous monitoring of humidity and temperature by polarization volume gratings utilizing responsive cholesteric liquid crystals

Optical sensing devices are utilized for noncontact operation in harsh environments due to their advantage of local separation between the measurement and detector systems. Cholesteric liquid crystals (CLCs) with vivid structural colors are integrated into optical sensors, attracting significant interest for naked-eye detection. To enable vision-based, real-time remote monitoring, we propose a cost-effective method to convert the stimuli-responsive reflection change of CLCs into recordable diffraction patterns using polarization volume gratings (PVGs). This enables real-time remote readout of environmental parameters. PVGs are constructed through holographic polarization interference and photoalignment technologies. The diffraction efficiency of PVGs varies with relative humidity (RH). To improve sensing accuracy and extend the monitoring range of RH, we employ two methods: an orthogonal grating structure and dual-wavelength detection optical path. In addition, we demonstrate the simultaneous measurement of humidity and temperature by cascading independently responsive PVGs. We believe that this work will provide a broader perspective and expand the application of light dimensions in LC-based optical sensing.

Lanthanide complexes with (4,7-dichloro-1,10-phenanthroline-2,9-diyl)bis(pyrrolidin-1-ylmethanone): bifunctional materials for homogeneous catalysis and luminescent thermometry

The first bifunctional materials for simultaneous catalysis and temperature measurements were obtained based on europium and ytterbium complexes with (4,7-dichloro-1,10- phenanthroline-2,9-diyl)bis(pyrrolidin-1-ylmethanone). The complexes demonstrated intense visible and NIR luminescence, the ability to homogeneously catalyze the Henry reaction, and high luminescence sensitivity to temperature (Sr = 1.7% K−1).

Simultaneous detection of soot, temperature, and C2H2 in laminar premixed flames using a multi-pass diode laser absorption spectrometer.

We report the development of a multi-pass diode laser absorption spectroscopy system for simultaneous measurements of soot volume fraction (SVF), temperature, and C2H2 concentration using a single diode laser near 1.543 µm. A line-shaped beam spot pattern is chosen for the open-path Herriott multi-pass cavity, enabling sensitive detection at various heights above the burner with an effective optical absorption path length of approximately 1.2 m in a 6 cm diameter flame region. The gas parameters (temperature and C2H2 concentration) and the SVF are determined from the absorption spectra of the target C2H2 line pair and the laser extinction of the soot, which can be extracted from the detected signal, respectively. The performance of the system was confirmed in laminar premixed ethylene and air (C2H4/air) sooting flames produced by a standard bronze plug McKenna burner at four representative equivalence ratios. All the measurement results were compared with the two-dimensional (2D) computational fluid dynamics (CFD) simulations using a skeletal mechanism with the Moss-Brookes model. The good quantitative and qualitative agreement between the TDLAS measurements and 2D CFD simulations confirms the powerful capability of the developed system.

Ultrasensitive optical electric field sensor with temperature compensation for point-wise and quasi-distributed sensing.

A point-wise and quasi-distributed optical sensing technique with the Vernier effect is proposed and achieved by multiplexing Fabry-Perot interferometers (FPIs). The FPIs are fabricated by LiNbO3 (LN) crystals of varying lengths to enable simultaneous measurement of electric field (E-field) and temperature. Compared to the traditional bulk-type optical E-field sensors, this innovative sensor enables E-field measurement without being limited by half-wave voltage and effectively avoids the influence of natural birefringence. By an algorithm based on the Fourier transform, sub-FPIs are addressable, and their interference spectra can be demodulated independently, where any two FPIs are paired to generate the fundamental Vernier effect (FVE) or harmonic Vernier effect (HVE). Thus, the measurement sensitivities of FPIs can be significantly improved by monitoring the spectral shift of the envelope in the superimposed spectra. The quasi-distributed sensing experiment is conducted using three cascaded FPIs, yielding E-field sensitivities of 2.84 nm/E (FVE) and 3.37 nm/E (HVE), with a standard deviation (STD) of spectrum variation after temperature compensation below 3.19 × 10-3. The proposed multiplexing method is significant for practical applications of the E-field quasi-distributed measurement.

Wearable and Multiplexed Biosensors based on Oxide Field-Effect Transistors.

Wearable sensors designed for continuous, non-invasive monitoring of physicochemical signals are important for portable healthcare. Oxide field-effect transistor (FET)-type biosensors provide high sensitivity and scalability. However, they face challenges in mechanical flexibility, multiplexed sensing of different modules, and the absence of integrated on-site signal processing and wireless transmission functionalities for wearable sensing. In this work, a fully integrated wearable oxide FET-based biosensor array is developed to facilitate the multiplexed and simultaneous measurement of ion concentrations (H+, Na+, K+) and temperature. The FET-sensor array is achieved by utilizing a solution-processed ultrathin (≈6nm thick) In2O3 active channel layer, exhibiting high compatibility with standard semiconductor technology, good mechanical flexibility, high uniformity, and low operational voltage of 0.005V. This work provides an effective method to enable oxide FET-based biosensors for the fusion of multiplexed physicochemical information and wearable health monitoring applications.

MZI-based high intensity responsive sandwiched multi-layer fiber optic humidity sensor

This paper presents a multi-layer optical fiber humidity sensor based on dual-beam Mach-Zehnder interference (MZI) for optical intensity sensitivity. The sensor is fabricated using a large-scale axial offset fusion technique between a multimode fiber (MMF) and an offset hole two-core fiber (OHTC), making it suitable for agricultural and health monitoring applications. The 27 μm axial offset enables tilted light incidence, enhancing environmental sensitivity. With a single-cycle Graphene oxide (GO) coating of approximately 22 nm, the MMF-OHTC structure achieves high humidity sensitivity (0.39 dB/%RH) over the 25 %-80 % RH range with excellent linearity (R2≈0.99). The sensor exhibits stable, rapid response (2.52 s/0.46 s) and low temperature cross-sensitivity (0.06 %RH/°C). When combined with a hollow-core fiber Fabry-Perot interferometer (HCF-FPI), the system allows zero cross-talk simultaneous humidity and temperature measurements, expanding the potential applications of multi-layered structures in multifunctional detection systems.

Simultaneous measurement of temperature and C2H4 concentration in hydrocarbon flames using interference-immune differential absorption spectroscopy at 3.3 μm

In diagnostic applications based on tunable diode laser absorption spectroscopy, the measurement of target substances can be influenced by factors such as background thermal radiation in the combustion environment, extinction caused by solid or liquid particles, and other interfering absorptions. In this work, we developed a differential absorption diagnostic technique based on wavelength pairs, utilizing an interband cascade laser near 3.3 μm to simultaneously measure temperature and C2H4 concentration in hydrocarbon flames. Based on a detailed study of the C2H4 spectrum in this region and considering the optimal standard for spectral lines, two wavelength pairs were selected. The temperature is determined by the ratio of the absorption cross-sections of two wavelength pairs, and the C2H4 concentration is inferred based on the wavelength pair with higher differential absorption. In the initial stage, the system’s accuracy was verified in high-temperature static conditions (T = 300–800 K, P = 1 atm), and continuous time series measurements demonstrated the system’s stability. The limit of detection achieved by Allan-Werle variance analysis is 2.5 ppm at the optimal average time of 100 s. Subsequently, measurements were taken in a hydrocarbon flame. The obtained results indicate an average deviation of 1.021 % between the measured temperature in the flame and the reference value, with a standard deviation of 1.381 % for concentration measurement. All the measurements show that the system can be potentially applied to combustion diagnosis.

Highly sensitive push-pull differential pressure sensor with multi-parameter measurement capabilities

A multi-parameter sensor comprising of a Fabry–Perot (FP) pair and a fiber-optic FP microcavity was proposed for simultaneous measurement of differential pressure (DP), static pressure (SP) and temperature. The push-pull FP pair is used to measure the differential pressure, and wide measurement range can be achieved by adjusting the dimensions of the diaphragm. The self-enclosed fiber-optic microcavity is utilized to measure the static pressure. For multi-parameter measurement, a matrix equation is proposed to solve the differential pressure, static pressure and temperature by fully considering the relationship of the FP cavity lengths and measurands. The performance of multi-parameter sensing is verified experimentally. The sensitivities of differential pressure, static pressure and temperature are 294.4822 nm/KPa, 353.08 nm/MPa and 42.4056 nm/°C, respectively, in variation of cavity lengths. The sensing characteristics show good linearity. Such a sensor could find important applications in the fields of process industry and oil industry, etc.

An ultrafast optical sensor for simultaneous detection of NH3 temperature and concentration based on ultraviolet absorption spectral redshift combined with spectral reconstruction

As a renewable and carbon-free fuel with high energy density, ammonia (NH3) is a promising alternative to fossil fuels. Real-time detection of its temperature and concentration is significant in improving NH3 combustion efficiency. In this paper, we report an optical sensor, which enables simultaneous measurement of temperature and concentration of NH3. The key idea is to acquire the temperature of NH3 through absorption spectral redshift, and determine its concentration by building three-dimensional field map combined with spectral reconstruction. Firstly, we explain the generation mechanism of temperature-induced redshift in ultraviolet differential absorption spectrum based on energy level distribution theory. The relationship between spectral redshift and temperature is then established using spectral autocorrelation algorithm. Secondly, a spectral reconstruction method based on absorbed intensity mapping wavelength is proposed to ensure real-time detection of NH3. Finally, a three-dimensional field map between temperature, reconstruction slope, and concentration is constructed to achieve the detection. Results indicated that the mean relative error in temperature measurement was 1.04 % and the mean absolute error in concentration detection was 0.26 mg/m3 in air. Additionally, the NH3 sensor enabled long-term detection with a detection limit of 15.50 μg/m2, demonstrating its potential to broaden the application of NH3 as a fuel.

Sensing performance comparison for temperature and liquid level sensor based on uniform and step-Etched microfiber TFBG

By using the hydrofluoric acid uniform-etching and step-etching methods, a tilted fiber Bragg grating (TFBG) microfiber structure was fabricated, where the cladding diameter of the traditional TFBG was reduced to micrometer scale. The temperature sensing characteristics of the uniform-etched and step-etched microfiber TFBGs were experimentally studied and compared. The core mode of its transmission spectrum was used for sensing the temperature change; while the normalized area of cladding modes has been used for real-time monitoring the liquid level. The simultaneous measurement of temperature and liquid level has been experimentally demonstrated for the proposed microfiber TFBG. By combining the strong evanescent field of microfiber and the unique structural advantages of TFBG, the proposed microfiber TFBG has a great potential in developing the miniature optical fiber sensors.

Transverse magnetic field effects on diamond quantum sensor for EV battery monitor

Key implementation points for achieving full accuracy in simultaneous temperature and magnetic field measurement and linearity when applying diamond quantum sensors to electric vehicle (EV) battery monitors were investigated. Both the static and busbar current magnetic field are required to be aligned to the NV-axis. If misalignment should exist, the resonance frequency midpoint move in the direction opposite to the temperature change under a large busbar current due to the transverse magnetic field effect. Misalignment could be quantified with an accuracy of ±1° by analysing the resonance frequency midpoint change under a current of ±1,000 A. The transverse magnetic field effects compensation estimated from misalignment, confirmed that the resonance frequency midpoint changed consistently with temperature changes. Furthermore, linearity over a wide dynamic range also improved. Moreover, it will contribute to accurate alignment of the two sensors for differential detection to eliminate external noise as common mode. These are expected to expand the application of diamond sensors for high-precision measurement in a wide dynamic range.