Sensitive Temperature Sensor Research Articles

A compact, highly sensitive optical fiber temperature sensor based on a cholesteric liquid crystal polymer film

A compact, highly sensitive optical fiber temperature sensor based on a cholesteric liquid crystal polymer film

An optical fiber high sensitivity temperature sensor with MZI and FPI parallel connection

Accurate detection of temperature is of great significance in the field of medical research. The focal point of this article centers around an optical fiber sensor that integrates Fabry Perot interferometer (FPI) filled with polydimethylsiloxane (PDMS) and Mach Zehnder interferometer (MZI), leveraging the principle of the vernier effect. By introducing the vernier effect principle, the sensitivity is 31.09 nm/°C in the detection range of 36 ∼ 40°C, and the maximum temperature measurement error is about 0.55 %. In addition, good linear response and longtime stability make it suitable for application in various scenarios where accurate temperature measurement is required.

A Highly Sensitive NiO Flexible Temperature Sensor Prepared by Low-Temperature Sintering Electrohydrodynamic Direct Writing.

Flexible temperature sensors have diverse applications and a great potential in the field of temperature monitoring, including healthcare, smart homes and the automotive industry. However, the current flexible temperature sensor preparation generally suffers from process complexity, which limits its development and application. In this paper, a nickel oxide (NiO) flexible temperature sensor based on a low-temperature sintering technology is introduced. The prepared NiO flexible temperature sensor has a high-resolution temperature measurement performance and good stability, including temperature detection over a wide temperature range of (25 to 70 °C) and a high sensitivity performance (of a maximum TCR of -5.194%°C-1 and a thermal constant of 3938 K). The rapid response time of this temperature sensor was measured to be 2 s at 27-50 °C, which ensures the accuracy and reliability of the measurement. The NiO flexible temperature sensor prepared by electrohydrodynamic direct writing has a stable performance and good flexibility in complex environments. The temperature sensor can be used to monitor the temperature status of the equipment and prevent failure or damage caused by overheating.

Controllable Fabrication of Multifunctional Micro-thermocouples for Temperature Detection inside Single Suspended Droplets.

Microdroplets have recently emerged as an exciting technological platform for wide applications. In this work, we developed a controllable fabrication approach to novel tungsten-platinum micro-thermocouples that function not only as a sensitive temperature sensor but also as a flexible suspender for individual microdroplet studies. The controllable fabrication hinges on the formation of tungsten tip apex nodes to make junctions with platinum, which was achieved through a unique combinational strategy, involving gradient coating with a complete insulating layer and subsequent targeted removal by tip electroporation. Benefiting from its coaxial structure, microspherical contact node end, hydrophobic surface, and thermoelectric performance, the as-fabricated micro-thermocouple was successfully employed for the microdroplet suspension and in situ temperature detection throughout the droplet evaporation cycle. It was observed that the temperature inside the suspended microdroplets was lower than that of the external environment, and there existed temperature discontinuity during droplet evaporation. By integrating the capabilities of temperature monitoring and droplet manipulation into a single micro-thermocouple, this work demonstrates its versatility and promising applications in expanded sensing for single microdroplets and other microsystems.

Non-Markovian enhancement of nonequilibrium quantum thermometry.

Accurate measurement at low temperatures is essential for both gaining a fundamental understanding of physical processes and developing technological applications. In this paper, we propose a theoretical framework for quantum temperature sensing in a composite environment with non-Markovian dynamics. Our suggested system uses a single qubit as a temperature sensor to test its sensitivity in calculating the temperature of a composite environment. We show that the temperature sensor's sensitivity can saturate the quantum Cramér-Rao bound by measuring the σ[over ̂]_{z} observable of the probe qubit. Temperature sensing performance is measured using the quantum signal-to-noise ratio. We underline how non-Markovianity can enhance the performance of our thermometers. Furthermore, we emphasize that nonequilibrium conditions do not always result in the best sensitivities in temperature estimation.

Highly Sensitive Wide Detection Range Semicircular Convex Slot PCF Temperature Sensor Based on Surface Plasmon Resonance

Highly Sensitive Wide Detection Range Semicircular Convex Slot PCF Temperature Sensor Based on Surface Plasmon Resonance

Dual-core fiber temperature sensor based on bending assist and spot pattern demodulation

A high sensitivity temperature sensor based on spot pattern demodulation of rare doped dual-core fiber (RDCF) is proposed. By utilizing the interference and scattering in RDCF, the related temperature variations can be captured by optical field. Furthermore, In order to improve the sensitivity, the RDCF is given a certain amount of bending. Due to the change of the spot mode caused by bending, the temperature changes more to the refractive index of the fiber core, so that the spot of the fiber changes more to facilitate the subsequent spot identification. In addition, considering the global and subtle nature of spot changes, a deep learning algorithm based on AlexNet transfer model is used to process image recognition at multiple temperatures. The experimental results show that the sensor can perceive different temperature in range of 30–199 °C, and the resolution is higher than 0.05 °C. These outstanding results indicate that the bending assisted temperature sensor based on spot pattern decoding of RDCF has potential applications in temperature quantitative sensing and artificial intelligence perception.

Temperature-Sensitive Sensors Modified with Poly(N-isopropylacrylamide): Enhancing Performance through Tailored Thermoresponsiveness.

The development of temperature-sensitive sensors upgraded by poly(N-isopropylacrylamide) (PNIPAM) represents a significant stride in enhancing performance and tailoring thermoresponsiveness. In this study, an array of temperature-responsive electrochemical sensors modified with different PNIPAM-based copolymer films were fabricated via a "coating and grafting" two-step film-forming technique on screen-printed platinum electrodes (SPPEs). Chemical composition, grafting density, equilibrium swelling, surface wettability, surface morphology, amperometric response, cyclic voltammograms, and other properties were evaluated for the modified SPPEs, successively. The modified SPPEs exhibited significant changes in their properties depending on the preparation concentrations, but all the resulting sensors showed excellent stability and repeatability. The modified sensors demonstrated favorable sensitivity to hydrogen peroxide and L-ascorbic acid. Furthermore, notable temperature-induced variations in electrical signals were observed as the electrodes were subjected to temperature fluctuations above and below the lower critical solution temperature (LCST). The ability to reversibly respond to temperature variations, coupled with the tunability of PNIPAM's thermoresponsive properties, opens up new possibilities for the design of sensors that can adapt to changing environments and optimize their performance accordingly.

High Sensitivity Temperature Sensor Based on Directional Coupler in a Liquid-Filled Tapered Hollow Suspended Dual-Core Fiber

High Sensitivity Temperature Sensor Based on Directional Coupler in a Liquid-Filled Tapered Hollow Suspended Dual-Core Fiber

Thermal and light-driven soft actuators based on a conductive polypyrrole nanofibers integrated poly(N-isopropylacrylamide) hydrogel with intelligent response

The development of soft hydrogel actuators with outstanding mechanical properties, fast actuation speed, and available quantification of self-sensing actuation remains a challenging endeavor. In this work, dopamine-decorated polypyrrole nanofibers (DAPPy) were introduced into the polyethylene glycol diacrylate (PEGDA)-crosslinked poly(N-isopropyl acrylamide) network to generate a stretchable, NIR-responsive, and strain sensitive DAPPy/PNIPAM hydrogel layer. Besides, this active layer was combined with the passive ligninsulfonate sodium/polyacrylamide (LS/PAAM) to give DAPPy/PNIPAM//LS/PAAM bilayer hydrogel actuator, which exhibits ultrafast thermo-responsive actuation (19°/s) and underwater grasping and lifting performance. Moreover, the DAPPy/PNIPAM layer has excellent electrical conductivity (0.29 S/m) and thermal conversion ability (10.8 °C/min), which enable such a conductive hydrogel to act as a highly sensitive strain and temperature sensor with real-time resistance change in response to tensile strain (gauge factor up to 3.4), applied pressure, temperature, and remote NIR light irradiation. More importantly, the bilayer hydrogel actuator can integrate both actuation and self-sensing functions through the bending angle-surface temperature-relative resistance change relationship of the photothermal process. With excellent mechanical actuation and self-sensing ability, the resulting bilayer hydrogel showed a promising application potential as soft biomimetic actuating materials and soft intelligent actuators.

A highly sensitive temperature sensor based on long period fiber grating coated with polymer-bilayer-membrane

This study introduces a highly sensitive temperature sensor based on long-period fiber grating (LPFG). The sensor is composed of a long period fiber grating covered by a higher RI (RI) layer of polyvinyl alcohol (PVA) and a lower RI layer of polydimethylsiloxane (PDMS). The PVA layer enables the sensor to operate in the mode transition region with high sensitivity, and the PDMS layer further enhances the temperature sensitivity owing to its high thermos-optic coefficient. In addition, the sensor can mitigate the influence of humidity due to the hydrophobic properties of PDMS. Experimental results show that the temperature sensitivity can achieve to 1232.3 pm/℃ within the range of 20℃-100℃ for an LPFG with a period of 363 μm coated with a 265 nm PVA layer and a 20 μm PDMS layer.

Ultra-sensitive temperature sensor based on PDMS filled Fabry-Perot cavity and air-bubble Fabry-Perot cavity in parallel

Highly sensitive fiber optic temperature sensors are designed and fabricated using the Vernier Effect (VE) and First-order Harmonic Vernier Effect (FHVE). The sensor comprises two Fabry-Perot cavities (F-P) in parallel. Single-mode fiber is fused together with a small segment of capillary, and then polydimethylsiloxane (PDMS) is filled in the capillary to form a sensing F-P cavity. The reference F-P cavity is composed of air-bubble inside the single-mode fiber etched by femtosecond laser. Two reference interferometers FPI1 and FPI2, as well as two sensing interferometers FPI3 and FPI4, were prepared using this method. The free spectral ranges (FSR) of FPI1, FPI2, FPI3, and FPI4 are 14.09 nm, 7.80 nm, 7.01 nm, and 6.48 nm, respectively. The temperature sensitivities of FPI3 and FPI4 are 2.2622 nm/°C and 2.4958 nm/°C, respectively. FPI1 and FPI2 are almost insensitive to temperature. FPI3 and FPI2 have similar FSR, and they generate traditional VE sensor in parallel, with a temperature sensitivity of 20.41 nm/°C, which is about 9.02 times that of FPI3. The FSR1 of FPI1 is approximately twice that of FPI3, and they generate FHVE1 in parallel. The temperature sensitivity of FHVE1 reaches −99.66 nm/°C, which is 44.05 times that of FPI3 and 4.88 times that of VE1. This is currently the highest known temperature sensitivity. In addition, the FSR1 of FPI1 is also approximately twice that of FPI4. Parallel connection between FPI4 and FPI1 can also generate FHVE2, but the sensitivity is only 22.17 nm/°C, which is 4.5 times lower than the sensitivity of FHVE1. From this, it can be seen that in FHVE, the smaller the FSR detuning (FSRr - (i+1) FSRs) between the sensing cavity and the reference cavity, the greater the amplification factor of sensitivity. The materials of the proposed sensor are cheap, easy to fabricate, and has high sensitivity. It can be used to measure temperature in environments with high sensitivity requirements.

Discharge splicing-free ultra-highly sensitive fiber-optic temperature sensor based on PDMS and the Vernier effect

A novel discharge splicing-free ultra-highly sensitive fiber-optic temperature sensor, based on polydimethylsiloxane (PMDS) and the Vernier effect, is constructed and experimentally validated. The sensor comprises single mode fiber (SMF), hollow core fiber (HCF), and PDMS. The Vernier effect is produced by the PDMS cavity and the mixed PDMS-air cavity during fabrication. By virtue of the Vernier effect and the temperature-sensitive material PDMS, this sensor shows an exceptionally high temperature sensitivity of −4.08658 nm/℃ while maintaining an outstanding linearity of 0.99972. The repeatability and stability have been demonstrated by subjecting the sensor to three cycles of heating and cooling, each with a 24-hour interval. Furthermore, experimental results indicate that the sensor exhibits excellent resistance to microvibrations and the interference occurs inside the structure, enabling its reliable operation in harsh environments without additional package. The miniature fiber temperature sensor is easily fabricated, highly sensitive, and demonstrates exceptional stability and repeatability, serving an ideal alternative for measuring temperature in challenging conditions.

A novel vinyl-bridged graphene oxide/polycarbosilane precursor for harsh environment-resistant ceramic temperature sensor

Ceramic temperature sensors are promising for automobile and jet engine monitoring but lack suitable materials and manufacturing methods. Herein, we designed and synthesized a novel vinyl-bridged graphene oxide/polycarbosilane (v-GO/PCS) hybrid precursor that could be easily shaped and pyrolyzed into reduced graphene oxide/silicon carbide (rGO/SiC) film as a stable and sensitive temperature sensor under harsh environments. As a result, 1 %-rGO/SiC ceramic film exhibited a fast response in the temperature range of 100 °C to 1000 °C. The rGO acted as a bridge linking the surrounding SiC grains, which significantly reduced the amount of thermal energy required for the directional transfer of electrons, leading to an increase in both the detection range and sensitivity of the sensor. The introduction of dry air, water vapor and acid (or alkali) atmosphere in the high-temperature conditions further verified its excellent stability. This work provides a simple and practicable strategy for highly stable temperature detection under harsh environments.

Na5Y9F32:Yb3+/Ho3+/Tm3+ up-conversion luminescent single crystals for highly sensitive optical temperature sensor

A novel non-contact optical temperature sensor with excellent performance of its adequate temperature resolution (δ(T) = 0.017 K) and exceptional relative thermal sensitivity (Sr = 1.97% K−1) was developed based on the up-conversion fluorescence intensity ratio (FIR) of Ho3+/Tm3+/Yb3+ triply incorporated Na5Y9F32 single crystal grown by Bridgman method. The up-conversion (UC) emission bands at 482 nm/669 nm/700 nm of Tm3+ and 522 nm/542 nm/653 nm of Ho3+ ions were observed upon excitation of 980 nm. The effects of Yb3+ concentration from 0.5 to 4 mol% on the UC emission of the Ho3+/ Tm3+ fixed doped Na5Y9F32 single crystal were also carried out. It has been demonstrated through the calculation of the steady-state rate equation that the intensity of UC emission is linearly heightened with the pump power, confirming the conversion mechanism. The temperature sensing performance of the Ho3+/Tm3+/Yb3+ incorporated Na5Y9F32 single crystals was explored by analyzing the FIR employing thermally coupled energy levels (TCLs) and non-thermally coupled energy levels (NTCLs). The maximum values of absolute sensitivity (Sa) and relative sensitivity (Sr) of the material are estimated to be 19.1% K−1 (323 K) and 1.97% K−1 (398 K), separately, which are far higher than those of previously reported RE3+-doped UC optical temperature sensor materials. This study shows that the transparent single crystal has the great potential as a non-contact optical thermometer, and provides a new idea for studying other highly optical sensing materials.

High sensitivity and wide detection range temperature and refractive index photonic crystal fiber sensor

A D-shaped surface plasmon resonance temperature and refractive index (RI) sensor based on photonic crystal fiber is proposed. The fiber core is composed of five air holes arranged in a pentagonal shape, which effectively improves the sensitivity. The gold film is used as a plasmonic material, and the mixture of ethanol and chloroform is used as a temperature sensitive liquid. A finite element method with higher accuracy and stronger applicability is used to study the performance of the sensor. The results indicate that when filling the mixture, the temperature sensor can detect the temperature in the range of 0 °C–60 °C. A maximum temperature sensitivity of 11.0 nm °C−1 is obtained by filling the mixture. The RI sensor can detect RI in the range of 1.13–1.40, with the wavelength range of 1.2–2.4 μm, and the maximum wavelength sensitivity reaches up to 21 000 nm RIU−1. The sensor can be used in biomedicine, environmental monitoring, food detection, temperature detection and other related fields, and has certain competitiveness and commercial value.

Toward Humidity-Independent Sensitive and Fast Response Temperature Sensors Based on Reduced Graphene Oxide/Poly(vinyl alcohol) Nanocomposites.

Flexible temperature sensors are becoming increasingly important these days. In this work, we explore graphene oxide (GO)/poly(vinyl alcohol) (PVA) nanocomposites for potential application in temperature sensors. The influence of the mixing ratio of both materials, the reduction temperature, and passivation on the sensing performance has been investigated. Various spectroscopic techniques revealed the composite structure and atomic composition. These were complemented by semiempirical quantum chemical calculations to investigate rGO and PVA interaction. Scanning electron and atomic force microscopy measurements were carried out to evaluate dispersion and coated film quality. The temperature sensitivity has been evaluated for several composite materials with different compositions in the range from 10 to 80 °C. The results show that a linear temperature behavior can be realized based on rGO/PVA composites with temperature coefficients of resistance (TCR) larger than 1.8% K-1 and a fast response time of 0.3 s with minimal hysteresis. Furthermore, humidity influence has been investigated in the range from 10% to 80%, and a minor effect is shown. Therefore, we can conclude that rGO/PVA composites have a high potential for excellent passivation-free, humidity-independent, sensitive, and fast response temperature sensors for various applications. The GO reduction is tunable, and PVA improves the rGO/PVA sensor performance by increasing the tunneling effect and band gap energy, consequently improving temperature sensitivity. Additionally, PVA exhibits minimal water absorption, reducing the humidity sensitivity. rGO/PVA maintains its temperature sensitivity during and after several mechanical deformations.

All-inorganic ultrathin high-sensitivity transparent temperature sensor based on a Mn-Co-Ni-O nanofilm

The demand for optically transparent temperature sensors in intelligent devices is increasing. However, the performance of these sensors, particularly in terms of their sensitivity and resolution, must be further enhanced. This study introduces a novel transparent and highly sensitive temperature sensor characterized by its ultrathin, freestanding design based on a Mn-Co-Ni-O nanofilm. The Mn-Co-Ni-O-based sensor exhibits remarkable sensitivity, with a temperature coefficient of resistance of −4% °C−1, and can detect minuscule temperature fluctuations as small as 0.03 °C. Additionally, the freestanding sensor can be transferred onto any substrate for versatile application while maintaining robust structural stability and excellent resistance to interference, indicating its suitability for operation in challenging environments. Its practical utility in monitoring the surface temperature of optical devices is demonstrated through vertical integration of the sensor and a micro light-emitting diode on a polyimide substrate. Moreover, an experiment in which the sensor is implanted in rats confirms its favorable biocompatibility, highlighting the promising applications of the sensor in the biomedical domain.

Enhanced sensitivity of temperature sensor by a novel birefringent photonic crystal fiber with PDMS filling

It is more than important to sensitively take the temperature in industrial production and experimental study. In this paper, the high-sensitivity temperature sensor based on high birefringent photonic crystal fiber is proposed. To increase the sensitivity, polydimethylsiloxane (PDMS) was filled into the internal elliptical air hole of the photonic crystal fiber (PCF) to propose the PDMS/silica hybrid PCF structures. Temperature is measured by the quantitative change in birefringence of the refractive index of the PDMS material with temperature. We designed it as a detection loop and obtain the temperature detection sensitivity of up to 8.01 nm/°C in the range of −20 °C–20 °C, which was 6.5 times higher compared to the sensitivity obtained by filling with ethanol. This enables the designed PCF temperature sensor to be used for real-time and accurate temperature monitoring in the fields of bio-detection, chemistry, pharmaceuticals, etc.

Research on sensitized Fiber Bragg Grating temperature sensor based on bimetal three-substrates.

Temperature is one of the most important physical quantities in the field of earthquake precursor observation. Aiming at the problem of low sensitivity in the Fiber Bragg Grating (FBG) temperature sensor, the sensitized FBG temperature sensor based on bimetal three-substrates is proposed. Through theoretical analysis of the bimetallic model, the structural parameters of the sensor are optimized, and the sensor is simulated and analyzed with ANSYS. Then, the sensor is developed according to the simulation results, and the temperature test system is built to test the performance of the sensor. The results show that the sensitivity of the temperature sensor is 49.3 pm/°C, which is about 4.9 times that of the bare FBG sensor, and the linearity is over 0.999. The research results provide a reference for developing the same type of sensors and further improving the sensitivity of FBG temperature sensors.