Sensitive Temperature Sensor Research Articles

Highly sensitive temperature and strain sensor based on an antiresonant hollow core fiber probe with the Vernier effect.

A highly sensitive temperature and strain sensor based on an antiresonant hollow core fiber (ARHCF) probe with the Vernier effect is proposed and experimentally demonstrated. The ARHCF probe is used as a reference interferometer by sandwiching an ARHCF, which is insensitive to temperature, strain, and refractive index, between a single-mode fiber (SMF) and a polarization-maintaining fiber (PMF). The polarization mode interferometer (PMI), fabricated by splicing a section of PMF with a fiber polarizer at a 45-degree angle, works as a sensing interferometer. The Vernier effect is introduced by connecting the reference interferometer and the PMI in parallel. The experimental results show that by introducing the Vernier effect, the temperature sensitivity is improved from -1.68 to -15.7nm/∘C and the strain sensitivity is improved from 5.09 to 47.65 pm/µε. The magnification is consistent with the theoretical results. The reference segment of the proposed sensor is not affected by ambient factors, which provides a new strategy and idea for the development of multiparameter sensors based on the Vernier effect.

Experimental and numerical evidence of using a Phononic membrane with the coupling of Fano resonant modes as a highly sensitive temperature sensor

In this article, we present numerically and experimentally a tunable phononic membrane as an efficient temperature sensor based on the generation of slow modes (sharp resonance modes) in microcavities. The Phononic membrane is periodically perforated with subwavelength slits (apertures) to produce tunable modes in these cavities (mode corresponding to a cavity resonance). By emerging the silicon membrane in water, a coupling effect between acoustic waves through the slits occurs, which leads to multiple-wave interferences like Fabry Perot resonators. Besides, this design could secure the phenomenon of ultrasonic opacity through the perforated silicon membrane. Where a deep and large attenuation band with a relative bandwidth of 31 % and at the central frequency of 0.9 MHz is observed in the amplitude transmission spectra of the phononic membrane. Secondly, by modifying the temperature of the water, the position of the bandwidth is tuned, since, we could achieve high sensitivity of 2400 Hz °C-1 for a temperature change of 10–20 °C, which is considered a promising result for many important applications such as temperature sensors and biosensors.

Temperature depended resistive property of fermented soybeans (Japanese natto) as a temperature sensor material

Carbon-based temperature-sensitive materials have become recent topics of interest due to high demands of human sensing. To enable the practical use of these temperature sensing devices, high sensitivity, easy fabrication and disposal, and low cost are essential characteristics that should be considered. However, all these characteristics do not appear simultaneously in existing sensors. In this study, we propose and fabricate a sensitive temperature sensor using fermented soybeans (Japanese natto) as the sensing element. Natto is a naturally derived material with temperature-dependent resistance and low environmental load. Moreover, its fabrication and disposal costs are low. The changes in the resistance of the natto sheet are shown to be dependent on its water content, and a temperature coefficient of resistance of 1.15% °C−1 is achieved. The fabricated sensor shows an experimental temperature sensitivity of at least 0.1 °C. These results indicate the promising potential of using the natto sheet as a temperature sensing element.

Highly sensitive and fast surface temperature sensor based on standard single-mode fiber using double heterodyne interference technology

Fiber optics can be ideal thermometers owing to their unique advantages. In this work, we propose a novel measurement method of double heterodyne interferometry, and construct a surface temperature sensor (STS) out of a standard single mode fiber (SMF) with high sensitivity and fast response. The STS is made of a coiled 1.2-m-long SMF, which can quickly sense small changes in ambient temperature by changing the phase of the light propagating in it. Using an oscilloscope, the proposed double heterodyne interferometry can precisely measure the phase change of the light and thus the temperature change, with a sensitivity of 4997°/°C and accuracy of ∼2 × 10−4 °C. A response time of ∼1 ms is obtained experimentally owing to the small SMF diameter, suggesting that a measurement frequency of ∼200 Hz is possible. Additionally, the sensor is characterized by its extended operating range from 0 to 200 °C.

Highly sensitive temperature sensing based on a birefringent fiber Sagnac loop

The usage of a 1 m Polarization Maintaining Fiber (PMF) as a passive sensing element for the experimental demonstration of a highly sensitive all-fiber temperature sensor based on a Sagnac interferometer configuration is presented here. Using a simple interrogation method tracing the wavelength shift of the obtained interference peaks, we were able to detect variations in a water bath temperature with a highly linear response with coefficient of determination (R2) of 0.9999 and a sensitivity of −1.59 nm/°C for the 18–42°C temperature range. This result demonstrates the feasibility of using this all-fiber device as a temperature sensor for many applications that demands very precise and reliable measurements.

Highly Sensitive Temperature Sensor Based on Cascaded Polymer-Infiltrated Fiber Mach-Zehnder Interferometers Operating near the Dispersion Turning Point.

High-accuracy temperature measurement plays a vital role in biomedical, oceanographic, and photovoltaic industries. Here, a highly sensitive temperature sensor is proposed and demonstrated based on cascaded polymer-infiltrated Mach–Zehnder interferometers (MZIs), operating near the dispersion turning point. The MZI was constructed by splicing a half-pitch graded index fiber (GIF) and two sections of single-mode fiber and creating an inner air cavity based on femtosecond laser micromachining. The UV-curable polymer-infiltrated air cavity functioned as one of the interference arms of MZI, and the residual GIF core functioned as the other. Two MZIs with different cavity lengths and infiltrated with the UV-curable polymers, having the refractive indexes on the different sides of the turning point, were created. Moreover, the effects of the length and the bending way of transmission SMF between the first and the second MZI were studied. As a result, the cascaded MZI temperature sensor exhibits a greatly enhanced temperature sensitivity of −24.86 nm/°C based on wavelength differential detection. The aforementioned result makes it promising for high-accuracy temperature measurements in biomedical, oceanographic, and photovoltaic applications.

Theoretical analysis of a highly sensitive SPR temperature sensor based on Ag/TiO2 hyperbolic metamaterials and PDMS film

We proposed and theoretically investigated a highly sensitive surface plasmon resonance (SPR) temperature sensor. The sensor is composed of a tapered no-core fiber (TNCF) deposited with hyperbolic metamaterials (HMMs) and a layer of polydimethylsiloxane (PDMS). The resonance wavelength can be tuned to longer wavelength that corresponds to higher temperature sensitivity and obtains a better product of depth of dip and figure of merit (DSD-FOM) by adjusting the parameters of the HMMs. The PDMS coated on the surface of the HMMs can further improve the temperature sensitivity due to its high thermal-optic coefficient. Simulation results show that the optimized temperature sensitivity can reach −16.26 nm/°C at 20 °C, and has an average DSD-FOM of 0.221 °C−1 in the range of 20 °C–70 °C, which is several times higher than that of Ag-SPR sensor.

Ultrasensitive Cryogenic Temperature Sensor Based on a Metalized Optical Fiber Fabry-Perot Interferometer

Cryogenic technologies are becoming essential in future applications in aerospace, quantum computing, cryogenic computing, and superconducting research. A highly sensitive temperature sensor is critical for such cryogenic applications. In this paper, we propose an extrinsic Fabry–Perot interferometer (EFPI) for cryogenic temperature measurement, leveraging the high thermal deformation of the copper sleeve to overcome the sensitivity drop issue in temperatures below 50 K for conventional cryogenic temperature sensors. Experimental results exhibit a temperature sensitivity of 2.836 nm/K throughout a temperature range of 5 K-50 K with a 15.82 μm long EFPI cavity, which is over three orders higher than the recently reported metal-coated FBG. The high sensitivity holds for the entire temperature range from 5 K to 295 K with excellent sensing repeatability. Our device, featuring a compact structure, and capability for multiplexing, is with great promise in cryogenic applications.

Highly sensitive temperature sensor based on a liquid crystal selectively infiltrated two-core photonic crystal fiber

This article proposes a temperature sensor based on liquid crystal selectively filled two-core photonic crystal fiber featuring high sensitivity and compact structure. In order to achieve the purpose of compact structure and temperature sensing, we consider to combine the temperature-sensitive material liquid crystal (LC) E7 and photonic crystal fiber to study the performance of temperature sensing. Since the applied electric field and temperature have great influence on the arrangement of liquid crystal molecules, LC as a temperature sensitive material can improve the sensing performance. An air hole filled with LC isolates the two horizontal cores, where the two horizontal cores act as two separate waveguides and the LC core is used to regulate the mode coupling of the two horizontal cores. In the process of transferring light energy from one core to another, the position of the transmission spectrum of the sensor is changed by optimizing the diameter of LC core and horizontal two-core, and then a sensor with high sensitivity and stable performance is designed. The coupling length and transmission spectrum of the sensor are analyzed by using full vector finite element method. By analyzing the wavelength dips of the transmission spectrum, the maximum sensitivity of the proposed temperature sensor can be reached −6.69 nm/℃ at 30 ℃ for Y-polarized (Y-Pol) direction. The main advantages of the sensor proposed in this paper are simple structure and easy to manufacture, high sensitivity and high fitting coefficient.

Simplified highly sensitive temperature sensor based on harmonic Vernier effect

Simplified highly sensitive temperature sensor based on harmonic Vernier effect

Optimization of Eu3+-to-Host Emission Ratio in Double-Perovskite Molybdenites for Highly Sensitive Temperature Sensors

Double-perovskite phosphors exhibit unusual thermal and luminescent behavior and could potentially be applied as efficient and sensitive luminescent temperature sensors. Four double perovskite hosts─Ba2MgMoO6 (BMM), Sr2MgMoO6 (SMM), Ba2ZnMoO6 (BZM), and Sr2ZnMoO6 (SZM)─are studied for the correlations between the symmetry, energetic structure, luminescence, and thermometric performance. The quantum yield of Eu3+ emission in those hosts is higher for the samples with high cubic symmetry and ranges up to over 20% for Ba2MgMoO6. The Eu3+ ions can be excited indirectly by the host absorption bands in the UV and charge transfer band (CTB) in the blue range. The symmetry of the host plays a crucial role in the thermal stability of the host emission, which together with varying activation energy of Eu3+ luminescence provides a basis for thermometric sensitivity optimization. The relative sensitivities (Sr) obtained by the Eu-doped molybdenite hosts are 3.2% at 75 °C for Sr2MgMoO6 and 9.2% at −196 °C for Ba2ZnMoO6. It is also demonstrated that the sensing performance is higher in hosts with a uniform quenching profile of host luminescence and steep quenching of Eu3+ luminescence.

Temperature sensing and bioimaging realized in NaErF4:40%Tm@NaYF4 with extremely intense red upconversion and suitable R/G emission ratio

The practical application of light thermometer based on the FIR (520/540) has been greatly limited due to the strong absorption of green light by biological tissues. The sensitivity of the temperature sensor located in a biological window (FIR-BW) also needs to be improved. Based on this, we designed and synthesized an upconversion nanoparticles (UCNPs) with suitable R/G ratio and red visual output to prebreaking the limitation of strong absorption of biological tissue, while improving the sensitivity of temperature sensor and in vivo fluorescence imaging. In this paper, NaErF4:40%Tm@NaYF4, a high efficient red UCNPs with R/G ratio (6.86), is first utilized as an optical thermometer, accomplished through the fluorescence intensity ratio (FIR) of thermally coupled stark sublevels of 4S3/2/4F9/2 (FIR(540/654)). In the studied temperature range, the maximum absolute and relative sensitivity (Sa and Sr) is 0.47% K−1 and 2.61% K−1 at 298 K, respectively, which is much higher than most previous reports about FIR-based temperature sensors. Additionally, we investigated the in vivo bioimaging behavior of NaErF4:40%Tm@NaYF4 in detail. The superior biocompatibility, the distribution to the main organs with the blood circulation system, and the bright red fluorescence signals were observed under 980 nm laser radiation. All the results imply that NaErF4:40%Tm@NaYF4 is a promising candidate for optical thermometry and in vivo bioimaging with high sensitivity.

Correction to: Highly sensitive temperature sensor in a parity-time-symmetric magnetomechanical system

Correction to: Highly sensitive temperature sensor in a parity-time-symmetric magnetomechanical system

In-fiber Fabry-Perot temperature sensor using silicone-oil-filled the quartz capillary tube

In this study, a highly sensitive temperature sensor based on a Fabry–Perot interferometer (FPI) filled with the silicone oil was designed and demonstrated. The FPI temperature sensor comprised an in-line sandwiched structure, i.e., single mode fiber – capillary – single mode fiber. A microchannel was processed on the capillary wall with a femtosecond laser. The capillary was filled with the silicone oil through the microchannel using the immersing method. Through theoretical analysis, the sensitivity of FPI temperature sensor is mainly determined by the thermo-optical coefficient of silicone oil. Owing to the high TOC of the silicone oil, the optical path difference (OPD) in the FP cavity varied strongly with temperature, which consequently induced a drastic wavelength shift of the reflection spectrum. Thus, FPI temperature sensor has high sensitivity. The temperature response, repeatability and stability of the sensor are studied experimentally. The results show that the temperature sensitivity of FPI sensor filled with silicon oil reaches −0.4102 nm/°C, which is about 205.1 times compared to that of the FPI sensor unfilled with silicon oil. The proposed sensor has the advantages of simple manufacturing, good robustness and stability. In addition, the total length of the sensor head is small, which is compact size and can be used flexibly in limited space and harsh environment.

Highly sensitive temperature sensor in a parity-time-symmetric magnetomechanical system

Highly sensitive temperature sensor in a parity-time-symmetric magnetomechanical system

Highly Sensitive Curvature and Temperature Sensor Based on Double Groove Structure and Hollow Core Fiber

In this paper, we propose a curvature and temperature sensor based on two symmetrical grooves and a hollow core fiber (HCF) filled with polydimethylsiloxane (PDMS). The two grooves are produced by splicing both ends of the polished HCF with two multimode fibers (MMFs). The proposed groove structure is sensitive to curvature, and the PDMS, with a high thermo-optical coefficient, makes the sensor highly sensitive to temperature. The experimental results show that the sensor exhibits a high sensitivity of −6.833 nm/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> in the curvature range of 0 m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> to 45.97m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> , and a high sensitivity of 4.278 nm/°C in the temperature range of 25°C to 95°C. The proposed sensor can monitor curvature and temperature simultaneously in real-time, and has potential application prospects in industrial production, biomedicine, structural health monitoring, and other fields.

Highly sensitive RI and temperature sensor based on an asymmetric fiber coupler.

We propose and demonstrate a highly sensitive refractive index (RI) and temperature sensor based on an asymmetric fiber coupler (AFC). The AFC was fabricated by weak fusion of a pre-stretched single-mode fiber and a few-mode fiber. An ultra-sensitivity RI can be achieved near the dispersion turning point (DTP). The proposed RI sensor achieves a high RI sensitivity of -10,662.4nm/RIU within the RI range of 1.31-1.35. By packaging the AFC into polydimethylsiloxane (PDMS), the temperature sensitivity reaches 11.44 nm/°C. The proposed AFC with high RI and temperature sensitivity can be potentially used in the field of chemical monitoring, biochemical detection, and clinical diagnosis.

Silicone Rubber Coated Non-Adiabatic Tapered Fiber Combined With Online Vernier Interferometer for Temperature Detection

A simple, robust, compact, and highly sensitive temperature sensor based on silicone rubber-sealed non-adiabatic tapered fiber (SR-NATF) is proposed and demonstrated. By combining with the fast Fourier transform (FFT) method, an online Vernier reference interferometer (OVRI) is constructed to enhance the temperature sensitivity. The temperature sensitivity is −1.30 nm/°C for the single SR-NATF in the temperature range of 35 °C – 40 °C. After utilizing the FFT method and cascading an OVRI, the temperature sensitivity can obtain 6.26 nm/°C, which is 4.82 times as that of a single SR-NATF. The proposed sensor is robust, soft and easy-fabrication which can be applied in human body temperature detection. In addition, the proposed method is efficient and convenient for the construction of an online reference arm based on Vernier-amplified sensitivity.

Carbonized Silk Nanofibers in Biodegradable, Flexible Temperature Sensors for Extracellular Environments.

Temperature is one of the key parameters for activity of cells. The trade-off between sensitivity and biocompatibility of cell temperature measurement is a challenge for temperature sensor development. Herein, a highly sensitive, biocompatible, and degradable temperature sensor was proposed to detect the living cell extracellular environments. Biocompatible silk materials were applied as sensing and packing layers, which endow the device with biocompatibility, biodegradability, and flexibility. The silk-based temperature sensor presented a sensitivity of 1.75%/°C and a working range of 35-63 °C with the capability to measure the extracellular environments. At the bending state, this sensor worked at promising response of cells at different temperatures. The applications of this developed silk material-based temperature sensor include biological electronic devices for cell manipulation, cell culture, and cellular metabolism.

Effect of Abduction Brace Wearing Compliance on the Results of Arthroscopic Rotator Cuff Repair

Background:The benefit of protective bracing after rotator cuff reconstruction has been debated for many years, although immobilization compliance has never been assessed objectively to date. In a previous study, compliance with the wearing of an abduction brace was measured for the first time with use of temperature-sensitive sensors. The purpose of the present follow-up study was to assess the effect of immobilization compliance on tendon-healing after rotator cuff repair.Methods:The clinical and radiographic outcomes for 46 consecutive patients with objectively assessed abduction brace wearing compliance after arthroscopic repair of a superior rotator cuff tear were prospectively analyzed. Rotator cuff integrity was examined with ultrasound. Clinical outcomes were assessed with the relative Constant-Murley score (RCS), the Subjective Shoulder Value (SSV), and pain and patient satisfaction ratings. Receiver operating characteristic (ROC) curves were used to determine the optimal cutoff value of abduction brace compliance for discriminating between shoulders that will and will not have a retear and the association of compliance with the failure of rotator cuff repair.Results:After a mean duration of follow-up of 20 ± 9 months, the odds ratio for having a rotator cuff repair failure was 13-fold higher for patients with a compliance rate of <60% (p = 0.037). The retear rate was 3% (1 of 35 patients) in the high-compliance cohort (≥60% compliance) and 27% (3 of 11) in the low-compliance cohort (<60% compliance) (p = 0.037). No differences in RCS, SSV, pain, or postoperative patient satisfaction were observed between patients with ≥60% compliance and those with <60% compliance.Conclusions:Patients with a compliance rate of <60% had a 13-fold increase in the risk of rotator cuff retear. The 2 patients with the lowest compliance rates (11% and 22%) both had retears. Due to the small sample size, no final conclusions can be drawn regarding the influence of immobilization compliance on tendon-healing after rotator cuff repair. These findings justify a prospective trial with a larger cohort to confirm or disprove the value of compliance with abduction bracing.Level of Evidence:Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.