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The ability to precisely monitor temperature at a high resolution is an important task, particularly in terms of safety. Inspired by natural thermosensitive transient receptor potential cation chan...

We report on a simple and cost-effective sensing scheme for humidity and temperature sensing, based on the generation of optical Vernier effect using two different fiber optic Fabry-Perot interferometers (FFPIs). By using an insensitive reference FFPI (rFFPI) and a sensitive FFPI (sFFPI) fabricated by hot and cold splicing methods, respectively, the complexity associated with the inherent traditional isolation schemes was mitigated, allowing to attain the maximum sensitivities of −2.69 nm/°C and −2.4 nm/% for temperature and relative humidity, respectively. The sensor’s performance combined with its simple and customizable configuration makes it a suitable option for applications with high-resolution requirements.

Temperature monitoring inside tissue undergoing minimally invasive thermal ablation is a primary goal to improve the clinical outcomes. Existing techniques for temperature measurements, classified as invasive or contactless, have limited clinical practice applications due to several practical issues. Fiber Bragg grating sensors (FBG) can be a valid solution since they can perform accurate and multi-point temperature measurements by inserting a single and small fiber optic within the tissue. Notwithstanding, their cross-sensitivity to strain may cause measurement errors during thermal procedures. Indeed, several organs (e.g., lungs, liver, pancreas) can strain gratings due to movements caused by breathing. To date, only a few studies have specifically addressed this concern, despite the wide use of FBGs in this field. To overcome this lack, we estimated the artefact of the FBGs output in response to lungs’ movements induced by breathing. This investigation was carried out by inserting FBGs within a manually ventilated lung model ( ex vivo swine lungs). We measured both the lungs’ movements during breathing by a Motion Capture system and the related fluctuations of the FBGs’ output. Moreover, we performed the same experiments during thermal ablation of lungs to assess the mentioned artefact’s influence. In this study, we demonstrated the relevance of the respiratory artefact on FBGs, and also the possibility to correct this error during thermal ablation.

Inaccurate placement of the ablation catheter and the inability to monitor the real-time temperature within the tissue of interest such as veins curbs the treatment efficacy of laser ablation procedures during thermal therapies. Our previous studies have validated the efficacy of photoacoustic (PA) imaging during endovenous laser ablation (EVLA) procedures. However, the PA-guided therapies suffer from low temporal resolution, due to the low pulse repetition rates of pulsed lasers, which could cause a problem during fast catheter motion and rapid temperature changes. Herein, to enhance the accuracy and sensitivity for tracking the ablation catheter tip and temperature monitoring, we proposed to develop a high frame rate (500 Hz), combined ultrasound (US), and PA-guided ablation system. The proposed PA-guided ablation system was evaluated in a set of ex vivo tissue studies. The developed system provides a 2 ms temporal resolution for tracking and monitoring the ablation catheter tip’s location and temperature, which is 50 times higher temporal resolution compared to the previously proposed 10 Hz system. The proposed system also provided more accurate feedback about the temperature variations during rapid temperature increments of 10°C per 250 ms. The co-registered US and PA images have an imaging resolution of about 200 μm and a field of view of 45 × 40 mm2. Tracking the ablation catheter tip in an excised tissue layer shows higher accuracy during a relatively fast catheter motion (0.5–3 mm/s). The fast US/PA-guided ablation system will potentially enhance the outcome of ablation procedures by providing location and temperature feedback.

Monitoring the temperature in liquid hydrogen (LH2) storage tanks on ships is important for the safety of maritime navigation. In addition, accurate temperature measurement is also required for commercial transactions. Temperature and pressure define the density of liquid hydrogen, which is directly linked to trading interests. In this study, we developed and tested a liquid hydrogen temperature monitoring system that uses platinum resistance sensors with a nominal electrical resistance of approximately 1000 Ω at room temperature, PT-1000, for marine applications. The temperature measurements were carried out using a newly developed temperature monitoring system under different pressure conditions. The measured values are compared with a calibrated reference PT-1000 resistance thermometer. We confirm a measurement accuracy of ±50 mK in a pressure range of 0.1 MPa–0.5 MPa.

Noncontact optical nanothermometry on the basis of fluorescence intensity ratio (FIR) has shown huge prospect in scientific research and real life owing to its excellent detection accuracy, rapid r...

In this paper, a polymer optical fiber (POF) is applied for temperature measuring of water solution using a light source of 650nm. The aim is to analyse the impact of temperature variations on the output of POF sensor device in terms of output power and sensitivity. From the study, the POF sensor shows a linear trend when the temperature is increased from 30°C to 80°C with the sensitivity of the polymer optical fiber for output power to the temperature are 0.00973 dBm/°C or 0.14797 nW/°C, for optical characterization and 0.0011 V/°C for electrical characterization. The integration of the Internet of Things to the system helps the user to monitor the temperature of various spaces anywhere at any time. The sensed values are controlled by Arduino Uno R3 and then sent to Blynk to provide wireless monitoring by the user.

In this article, we propose a temperature-based proportional–integral–derivative (PID) controlling algorithm using highly dense fiber Bragg grating (FBG) arrays for laser ablation (LA) of ex vivo pancreatic tissues. Custom-made highly dense FBG arrays with a spatial resolution of 1.2 mm were fabricated with the femtosecond point-by-point writing technology and optimized for LA applications. In order to obtain proper PID gain values, finite element method-based iterative simulation of different PID gains was performed. Then, the proposed algorithm, with numerically derived PID gains, was experimentally validated. In the experiments, the point temperature was controlled at different distances from the laser fiber tip (6.0, 7.2, 8.4, and 10.8 mm). The obtained results report robust controlling and correlation between controlled distance and the resulting area of ablation. The results of the work encourage further investigation of FBG array application for LA control.

Temperature monitoring plays an increasingly important role in research and industrial applications. Based on the influence of liquid crystal material thermal sensitivity on the capacitance of liqu...

An ultraviolet curable glue (UCG)-filled microprobe Fabry–Perot fiber temperature sensor, which based on the two-beam interference principle, is proposed and fabricated. In the range of 25.7–250 °C, the average sensitivity and average linear correlation coefficient of the sensor are −41.69 pm/°C and 0.98558, respectively. Under the same temperature, the maximum fluctuation (0.56 pm) of the trough’s wavelength and the standard error (0.0023 ± 0.04%) are obtained. The proposed interferometer exhibits excellent stability and has a potential application in the field of temperature monitoring.

The article is devoted to the development of a printed ultra-wideband miniature antenna that can be used for microwave radiometry. An antenna design with a ring-shaped radiator has been proposed, which provides reception of microwave radiation from biological tissues in the 1800–4600 MHz range. The results of mathematical modeling of the antenna electromagnetic field in biological tissues using the finite difference time domain (FDTD) method are presented. Optimization of the antenna design has been carried out to ensure acceptable matching parameters and optimal antenna functionality. The developed antenna has a height of 6 mm and a calculated mass of 5 g; it is planned to manufacture a dielectric substrate based on PDMS polymer with the addition of barium titanate. The issues of calculating the antenna parameters (measurement depth, resolution and distribution of radiation power over the volume of biological tissue, sensitivity, etc.) are considered. The research results and design parameters of the developed antenna demonstrated the effectiveness of the new antenna and the possibility of its adaptation to the object of research. Considering the presence of an ultra-wide band and miniature dimensions, the antenna can be a sensor of a multi-frequency multi-channel microwave radiothermograph

The surface quality and the subsurface properties such as hardness, residual stresses and grain size of a drill hole are dependent on the cutting parameters of the single lip deep hole drilling process and therefore on the thermomechanical as-is state in the cutting zone and in the contact zone between the guide pads and the drill hole surface. In this contribution, the main objectives are the in-process measurement of the thermal as-is state in the subsurface of a drilling hole by means of thermocouples as well as the feed force and drilling torque evaluation. FE simulation results to verify the investigations and to predict the thermomechanical conditions in the cutting zone are presented as well. The work is part of an interdisciplinary research project in the framework of the priority program “Surface Conditioning in Machining Processes” (SPP 2086) of the German Research Foundation (DFG). This contribution provides an overview of the effects of cutting parameters, cooling lubrication and including wear on the thermal conditions in the subsurface and mechanical loads during this machining process. At first, a test set up for the in-process temperature measurement will be presented with the execution as well as the analysis of the resulting temperature, feed force and drilling torque during drilling a 42CrMo4 steel. Furthermore, the results of process simulations and the validation of this applied FE approach with measured quantities are presented.

The results of research on cement composites with expanded graphite for application in temperature monitoring are presented. Two series of cement mortars were prepared with expanded graphite obtained from intercalated graphite by rapid heating at 500°C and 1000°C. The relation between temperature and electrical resistivity and the thermoelectric properties of the mortars with expanded graphite were investigated. Based on the measurements, the temperature coefficient of resistivity and the Seebeck coefficient were determined. The change in resistivity with temperature in heating–cooling cycles and the change in thermoelectric voltage for temperature gradient cycling were studied. Furthermore, the long-term resistance and thermoelectric voltage of mortars exposed to atmospheric conditions were measured. The results indicate that cement composites with expanded graphite exhibit very promising properties for temperature monitoring. It was found the composites containing expanded graphite obtained at 500°C were better for temperature monitoring by means of the Seebeck effect, whereas composites with expanded graphite obtained at 1000°C were suitable for temperature monitoring by means of resistivity change. Moreover, the results revealed that the percolation threshold of expanded graphite should be exceeded in the cement matrix in order to apply these composites in temperature monitoring by means of change of resistivity.

In this article, we determine the impact of laser parameters on the development of a flexible conductive transparent film in multi wall carbon nanotubes (MWCNTs) regular structures fabricated on th...

Temperature-sensing textiles have been proposed for a variety of applications, including health monitoring and sports. Skin temperature ( Tsk) measurements are an important parameter in performance sports and can be used to better understand thermoregulation during exercise. Currently, most Tsk measurements are taken using skin-mounted thermistors, which can be uncomfortable to the wearer, or thermal imaging, which can be difficult to implement and analyze. This work investigates the feasibility of using textile temperature-sensing electronic yarns (E-yarns) to measure human skin temperature during sub-maximal cycling trials. E-yarns were attached to commercially available cycling suits and measurements were recorded using both the E-yarns and the skin-mounted thermistors at rest and during sub-maximal cycling. Temperature readings were compared between the two temperature-sensing methodologies to determine the viability of using the temperature-sensing E-yarns for this application. Differences in the Tsk measurements as high as 5.9℃ between the E-yarns and skin-mounted thermistors for participants at rest have been shown. This work has also identified that a build-up of sweat significantly altered the Tsk recorded by the E-yarns in some cases. Further experiments explored the effect of saline solutions (simulating sweat) on the response of the temperature-sensing E-yarns. This work has highlighted boundary conditions for taking point Tsk measurement using electronic textiles.

Fiber optic distributed acoustic sensor (DAS) and distributed temperature sensor (DTS) are considerably important for many applications. It is challenging to design a hybrid DAS-DTS system using the same optical fiber because the operation principles of the two sensors are different. We here deploy the widespread standard multimode fiber (MMF) for simultaneous distributed acoustic and temperature sensing. In particular, we operate the MMF in a quasi-single-mode (QSM) state to simultaneously fulfill the functionality requirements of the DAS and DTS. The reported design offers simultaneous vibration and temperature monitoring with high accuracy. In particular, the DAS has a 12.98 dB mean signal-to-noise ratio (SNR) and the DTS offers temperature measurements with ±1 °C accuracy. This technique is significant for many industrial applications because it efficiently tackles a long-standing issue in practical implementation.

Mn0.55Fe1.25Cu2Ni2.2O4+δ glass-free thick films with negative temperature coefficient (NTC) character were fabricated on Al2O3 substrate by screen printing technology. The microstructural, electrical parameters, and cation distribution of materials varied with the slight change in sintering temperature (1000 °C, 1025 °C, 1050 °C) were investigated. All the thick film samples showed spinel structure of its main phase. CuAl2O4 phase was found when the sintering temperature was above 1025 °C, which is of practical importance for copper-containing thermal-sensitive materials bonding Al2O3 substrate. Both the room-temperature resistance R25 and material constant B value increased as temperature increased, R25 in the range of 17.3–125 kΩ, and B lying in the range of 2824–3074 K. Such feature was attributed to the redistribution of the multivalent state Mn, bivalence Fe and Cu cations with increasing sintering temperature. The optimal sintering temperature was 1000 °C due to its pure phase, best crystallinity, and lowest B value (2824 K), which was a good candidate for temperature monitoring and control in a relative widen temperature range.

Тemperature measurements in boreholes are widely used in oil and gas geophysics, hydrogeology, geoecology, geocryology, and in the operation of hydrothermal resources. The number of applications of borehole temperature data is continuously growing. Requirement for temperature measurement accuracy is also growing. However, increasing the accuracy is limitedby free thermal convection phenomenon (FTC). It occurs under a positive temperature gradient and causes temperature noise, the level of which may exceed the useful signal. It was believed for a long time that the FTC currentsare organized as a vertical sequence of convective cells having a certain vertical dimension.Existing methods of FTC suppressing by horizontal discsare based on these ideas.Theoretical and experimental studies conducted by the authors showed that these ideas are incorrect. FTC currents are organized as a rotating helical system of ascending and descending jets, not limited vertically.Under these conditions, the most efficient and technological way is dividing the borehole by vertical stripes of polymer film into separate segments.Another method of FTC suppressing uses spherical hydrogel granules. The test results of the developed devices in a real borehole are described. Using of these devices allows to reduce the temperature noise by 16-20 times (from 0.025 - 0.044 K to 0.002 - 0.003 K).

Real surface temperature of the molten pool was studied with an infrared image, and it was aim to evaluate the temperature filed with pulsed arc welding. A calculation and calibration algorithm wer...

To realize a real-time thermal feedback, monitoring the temperature of the treated tissue is critical for photothermal therapy (PTT). The poor spatial resolution and low accuracy of current methods for the detection of tissue temperature limits the application of PTT. Herein, by assembling the temperature-responsive DNA stem-loop marked with Texas red (TR) onto the surface of gold nanobipyramids (AuNBPs), a bifunctional reagent (AuNBPs-DNA-TR) was fabricated for PTT and synchronously monitoring the temperature. In this configuration, the AuNBPs not only have a high efficiency for photothermal conversion but also could be quenchers to inhibit the fluorescence of TR. During PTT, the significant photothermal effect of the AuNBPs could elevate the temperature. Meanwhile, the increase of the temperature could open the DNA stem-loop assembled on the AuNBPs and as a result enlarge the distance between the TR and AuNBPs. As a result, the TR fluorescence quenched by the AuNBPs was sensitively recovered. The fluorescence intensity (FI) of the TR could be utilized to monitor the temperature during PTT. It was found that irradiating the cancer cells cultured with the AuNBPs-DNA-TR with an 808 nm laser could distinctly increase the system temperature, while the cells could be inactivated due to the remarkable photothermal effect of the AuNBPs-DNA-TR. Meanwhile, the fluorescence of the AuNBPs-DNA-TR for the measurement of the temperature was significantly enhanced. The results indicated that the variation of the fluorescence from the AuNBPs-DNA-TR could be used as thermal feedback to monitor the effect of PTT.

In this study, a dipole antenna is designed for real-time damage assessment, humidity, and temperature monitoring in reinforced and non-reinforced concrete structures. The antenna-based sensor is embedded into reinforced and non-reinforced concrete beams to assess electromagnetic measurements. Reflection parameter S11 in dB values and resonant frequencies of the embedded antenna are evaluated to detect damage, humidity, and temperature changes. The exploratory results show that as deformation increases in reinforced concrete, resonance frequency values decrease and S11 values increase. The load and resonance frequency values showed very close trends as deformation increases in the beam. In water content sensing experiments, the S11 in dB values of the antenna decrease as the humidity increases for concrete specimens while the resonance frequency values increase as the humidity increases for the reinforced concrete specimen. Elevated temperature sensing experimental results show that the resonance frequency values of the antenna decrease as the temperature of the specimen increases for concrete specimens while the S11 in dB values increase as the temperature of the specimen increases for reinforced concrete specimen.

Endovenous laser ablation (EVLA) is a minimally invasive surgical procedure, often guided by ultrasound (US) imaging, for treating venous insufficiencies. US imaging limitations in accurately visualizing the catheter and the lack of a temperature monitoring system can lead to sub-optimal outcomes. An integrated photoacoustic (PA)-guided EVLA system has been previously developed and reported to overcome the shortcomings of US-guided procedure. In this study, we further characterized the system and tested the in vivo utility. In addition, PA thermometry was further explored by compensating the variation of PA signal with temperature with respect to the temperature-dependent absorption of blood and water. In vivo imaging results indicated that the PA-guided EVLA system can provide high contrast and accurate images of the ablation catheter tip overlaid on US images of the background tissue. Additionally, absorption-compensated PA signal amplitudes over a relevant range of temperature were measured and demonstrated.

ispartof: ADVANCED FUNCTIONAL MATERIALS vol:32 issue:5 status: published

Measuring temperature in various systems can be quite challenging, such as in power breakers, railway power lines contacts or in electric traction substations. This article presents an on-line monitoring system with Human Machine Interface to supervise the temperature of a high railway voltage separator. The temperature is measured using an infrared temperature sensor that converts the temperature in an electrical signal, which, afterwards, is used as an analogue input for the Siemens S7-1200 PLC.

Temperature reflects the balance between production and dissipate of heat. Flexible temperature sensors are primary sensors used for temperature monitoring. To obtain real-time and accurate information of temperature, different flexible temperature sensors are developed according to the principle of flexible resistance temperature detector (FRTC), flexible thermocouple, flexible thermistor and flexible thermochromic, showing great potential in energy conversion and storage. In order to obtain high integration and multifunction, various flexible temperature sensors are studied and optimized, including active-matrix flexible temperature sensor, self-powered flexible temperature sensor, self-healing flexible temperature sensor and self-cleaning flexible temperature sensor. This review focuses on the structure, material, fabrication and performance of flexible temperature sensors. Also, some typical applications of flexible temperature sensors are discussed and summarized.

Microwave thermal ablation (MTA) is a therapeutic technique employed for the eradication of tumors. It is based on the temperature increase achievable in biological tissues through the absorption of an electromagnetic field at microwave frequencies. Accordingly, a small antenna is inserted into the tumor to be treated, and it is allowed to radiate very high power values. Target temperatures are above 60°C, at which almost instantaneous coagulation occurs [1] . MTA is widely accepted as a very promising and powerful technique; however, actual devices lack a reliable, real-time, and objective method for temperature monitoring. To this end, several efforts are under way to develop new tools for temperature monitoring.

[EN] In this work, we obtained chirped Bragg gratings by post-coating uniform poly (methylmethacrylate) (PMMA) microstructured polymer optical fiber Bragg gratings (POFBGs) with an UV cure adhesive. The main advantage of the proposed method consists on being a cost-effective and simple solution, since no special phase mask, addi tional etching or gradient thermal annealing are required. A comparison between the fabricated chirped Bragg grating¿s performance and previous reported methods in the literature is presented. As a compact sensor with two different active areas (adhesive coated and uncoated sections of the POFBG), the developed sensing device can be used for multiparameter sensing, namely for strain, humidity and temperature monitoring. Allying the proposed flexible and low-cost fabrication technique with the intrinsic characteristics of POFs, one may conclude that the developed sensor has high potential for multiparameter sensing in possible future engineering and biomedical applications., National Natural Science Foundation of China (62003046) ; The Spanish Ministerio de Ciencia, Innovacion y Universidades RTI2018-101658-B-I00 FOCAL Project; Guangdong Basic and Applied Basic Research Foundation (2021A1515011997) ; Guangdong Recruitment Program of Foreign Experts (2020A1414010393) ; C. Marques ac-knowledges Fundacao para a Ciencia e a Tecnologia (FCT) through the CEECIND/00034/2018 (iFish project) and this work was developed within the scope of the project i3N, UIDB/50025/2020 &UIDP/50025/2020, financed by national funds through the FCT/MEC. Luis Pereira and Tiago Paixao also acknowledge FCT for the grant with references SFRH/BD/146295/2019 and PD/BD/128265/2016, respectively.

Fused Filament Fabrication (FFF) is presently one of the most commonly used Additive Manufacturing (AM) technology for various engineering applications. However, accuracy and stability remain a major challenge during AM processes. FFF is inherently a thermal process. So, it is important to analyze and monitor the temperature evolution of each deposited filament during and after printing. This work presents an in-situ temperature measurement setup with an infrared camera, used in collecting temperature profiles of printed layers. These temperature profiles were compared to a theoretical 1D heat transfer model, demonstrating good agreement between the two sets of data. The temperature measurement experiment has been repeated for different printing process parameters, namely print speed, flowrate, and bed temperature. The effect of fan cooling is also studied. These data play a significant role in determining the optimal settings needed to achieve the desired bonding between adjacent filaments. This can be concluded by studying the effect of changing the parameters on the cooling of each deposited filament concerning the material’s glass transition temperature. The average temperature of any two adjacent layers in a part has been evaluated and compared to the material’s glass transition temperature to provide a better insight on the quality of adhesion taking place. A visual inspection of the part has also been proven to be useful in evaluating the effect on the final quality.

Mechanical pain (or mechanical algesia) can both be a vital mechanism warning us for dangers or an undesired medical symptom important to mitigate. Thus, a comprehensive understanding of the different mechanisms of this type of pain is paramount. In this work, we study the tearing of porcine skin in front of an infrared camera, and show that mechanical injuries in biological tissues can generate enough heat to stimulate the neural network. In particular, we report local temperature elevations of up to 24 degrees Celsius around fast cutaneous ruptures, which shall exceed the threshold of the neural nociceptors usually involved in thermal pain. Slower fractures exhibit lower temperature elevations, and we characterise such dependency to the damaging rate. Overall, we bring experimental evidence of a novel - thermal - pathway for direct mechanical algesia. In addition, the implications of this pathway are discussed for mechanical hyperalgesia as well, in which a role of the cutaneous thermal sensors has long been suspected. We also show that thermal dissipation shall actually account for a significant portion of the total skin's fracture energy, making temperature monitoring an efficient way to detect biological damages., 13 pages, 8 figures, 1 table

A novel Hg2+-responsive thermometer system for translating mercury detection into temperature monitoring was developed based on an aggregation-activated oxidase-like activity of gold nanoparticles.

To overcome the existing challenge of temperature monitoring with high accuracy, we designed Sm3+-doped LiSrVO4 phosphors with ultra-high sensitivity as promising candidates for optical thermometers. The prepared samples could emit multicolor emissions after excitation at 343 nm and the optimum doping concentration for the Sm3+ ions in the selected host was 1 mol%. The mechanism of energy transfer from the VO43- group to the Sm3+ ions was studied and its efficiency was proved to be 84.1% for an Sm3+ ion content of 7 mol%. Based on the disparate thermal quenching performances of the VO43- group and Sm3+ ions, the temperature monitoring ability of the prepared compounds was examined. Through choosing different emissions of Sm3+ ions, and then combining them with the VO43- group, optical thermometers with controllable sensitivity were realized. The maximum absolute and relative sensitivities of the resultant phosphors could reach ultra-high values of 1.076 K-1 and 6.167% K-1, respectively, which were the highest sensitivities reported so far. Furthermore, the doping content also impacted the sensitivities of the resultant compounds.

In the paper a method of temperature monitoring for high frequency welding of soft tissues is presented. The method enables to investigate the distribution of temperature fields in biological tissues. This allows to assess the influence of the skin effect on current passage in a process of electrosurgical interventions.The present paper describes an investigation of distribution of temperature fields in biological tissues affected by electrosurgery upon use of an infrared thermograph. In the experiment, the dynamics of temperature distribution in the tissue was registered upon using thermal imaging cameras FLIR i7. Ablation of the tissues by HF current was performed with ЕКВЗ-300 unit (E.O. Paton Electric Welding Institute). Most important result of application of the method of temperature monitoring is an establishment of the moment for removal of the electrodes that ensures an avoidance of carbonization of the cardiac tissues during their ablation

Background Monitoring of temperature changes and accurately determining the moment of electrode removal during open heart operations is not well recognized. Objective We investigated the temperature fields distribution in the biological tissues affected by electrosurgery upon use of an infrared thermograph. Methods The dynamics of temperature distribution in the tissue was registered by the thermal imaging camera FLIR i7. Measurement of the temperature between electrode couples was carried out for two operation modes: coagulation (100% power) and coagulation (50% power). Results The most important result of the applied method of temperature monitoring is a determination of the moment for electrodes removal that ensures the avoidance of carbonization of the cardiac tissues during their ablation. Conclusions Temperature monitoring for connection of soft live biological tissues by welding allows the power to be fed in the amount sufficient for a formation of continuous ablation of the myocardium tissue.

Laser ablation can be used to treat atrial fibrillation by thermally isolating pulmonary veins. In this study, we evaluated the feasibility of high-resolution (1 mm) ultrasound thermal imaging to monitor spatial temperature distribution during laser ablation on ex vivo cardiac tissue.Laser ablation (808 nm) was performed on five porcine cardiac tissue samples. A thermocouple was used to measure the interstitial tissue temperature during the laser ablation process. Tissue-strain-based ultrasound thermal imaging was conducted to monitor the spatial distribution of the temperature in the cardiac tissue. The tissue temperature was estimated from the time shifts of ultrasound signals owing to the changes in the speed of sound and was compared with the measured temperature. The temperature estimation coefficient k of porcine cardiac tissue was calculated from the estimated thermal strain and the measured temperature. The degree of tissue coagulation (temperatures 50°C) was derived from the estimated temperature and was compared with that of the tested cardiac tissue.The estimated tissue temperature using strain-based ultrasound thermal imaging at a depth of 1 mm agreed with thermocouple measurements. During the 30-second period of the laser ablation process, the estimated tissue temperature increased from 25 to 70°C at a depth of 0.1 mm, while the estimated temperature at a depth of 1 mm increased up to 46°C. Owing to the uncertainty of the coefficient k, the k value of the porcine cardiac tissue varied from 160 to 220°C with temperature changes of up to 20°C. The estimated coagulation region in the ultrasound thermal imaging was 20% wider (+0.6 mm) but 9% shallower (-0.1 mm) than the measured region of the ablated porcine cardiac tissue.The current study demonstrated the feasibility of temperature monitoring with the use of ultrasound thermal imaging during the laser ablation on ex vivo porcine cardiac tissue. The high-resolution ultrasound thermal imaging could map the spatial distribution of the tissue temperature. The proposed method can be used to monitor the temperature and thermal coagulation to achieve effective laser ablation for atrial fibrillation. Lasers Surg. Med. © 2019 Wiley Periodicals, Inc.

In this work, we report a fiber Bragg grating (FBG) sensing system for a real-time temperature monitoring during a high-intensity focused ultrasound (HIFU) treatment of breast fibroadenoma. Temperature monitoring of the HIFU procedure within the treated area contributes to a successful outcome of a thermal ablation procedure by providing a valid feedback to the clinician. The unique characteristics of the FBG sensors make them a valid alternative to traditional sensing techniques for a variety of biomedical applications, including thermotherapies. The experiments were conducted on ex vivo breast fibroadenoma tissues. Results confirm that proposed setup is able to perform multipoint temperature measurements and to distinguish between consecutive ultrasound pulses.

A novel sensing technique for non-destructive and non-contact monitoring of the composites utilizing ferromagnetic glass-coated microwire inclusions with magnetic properties sensitive to tensile stress and temperature is proposed. We provide in-situ studies of the evolution of the hysteresis loop of arrays consisting of Co- and Fe-rich microwires, as well as transmission and reflection parameters of the composites with microwire inclusions during the composites matrix polymerization. We observed remarkable change of the hysteresis loops upon matrix polymerization: remarkable coercivity change and transformation of linear hysteresis loop to rectangular or from rectangular to linear for arrays with Co-rich and Re-rich microwires respectively. Using the free space technique we observed considerable variation of the reflection in the range of 4–7 GHz and transmission upon the matrix polymerization. Observed dependencies are discussed considering variation of temperature and stresses during the thermoset matrix polymerization and their influence on magnetic properties of glass-coated microwires.

Silicon carbide (SiC) is a primary candidate for passive irradiation temperature monitoring, and continuous dilatometry (CD) has been proposed as the key method for extracting irradiation temperatures from SiC thermometry samples. The CD method was evaluated to determine the sensitivity of the technique to the analysis procedure, as well as its accuracy and precision. Analysis found that the CD method had a ±20 °C sensitivity to the algorithm used to determine the irradiation temperatures. Comparison of the CD method with the continuous length change method for SiC thermometry showed CD is a more viable method of extracting irradiation temperatures. A comparison of irradiation temperatures determined by CD with those from active thermocouple measurements further validated the CD method for accurately and precisely determining irradiation temperatures in materials test reactor irradiations.

Objective: As a novel noninvasive modality of oncotherapy or stroke treatment, high-intensity focused ultrasound (HIFU) has drawn more and more attention in the past decades. Whereas, real-time temperature monitoring and treatment-efficacy evaluation are still the key issues for HIFU therapy. Methods: Based on the temperature–conductivity relation of tissues with a sharp conductivity variation of irreversible thermocoagulation at 69 °C, a noninvasive method of treatment-efficacy evaluation for HIFU ablation using the magneto-acousto-electrical tomography (MAET) technology is theoretically studied. By applying the nonlinear Khokhlov–Zabolotskaya–Kuznetsov equation and Pennes equation, a cylindrical model is established to simulate the distributions of pressure, temperature, and conductivity with the consideration of harmonic components. Results: The MAET signals are simulated to analyze the characteristics of the peak amplitude and the axial interval of the two clusters generated by the conductivity boundary of HIFU ablation. Conclusion: The axial interval can be used as the indictor to evaluate the size of HIFU ablation with the minimum axial width of one wavelength. Significance: The favorable results demonstrate the feasibility of real-time treatment-efficacy evaluation for HIFU therapy using the MAET technology and suggest potential applications in clinical practice.

Transparent chitosan (CS) film is prepared and its application in high temperature/fire warning is discussed. NaCl-doped chitosan (CS-NaCl) film shows excellent performance in real-time temperature monitoring and fire warning. The temperature warning of CS-NaCl film can be triggered under approximately 50 °C, and it has a good repeatable warning performance under high-temperature conditions. The CS composite film exhibits an ultra-sensitive (0.4 s) warning under fire attacking. A possible electrical conduction and fire-alarm mechanisms are proposed. The addition of NaCl increases the number of charge carriers, which improves the ionic conductivity of the composite film. This study provides a possibility for the application of CS in the field of fire warning.

Carbon fiber reinforced polymers (CFRPs) are particularly suitable for aerospace applications due to their specific mechanical properties. During their service life, these materials can suffer damage, sometimes difficult to detect, which may compromise their mechanical performances. The variation of the electrical properties of CFRPs is one of the strategies that can be used to monitor such damage. However, multiple variables contribute to this variation. This paper presents a preliminary analysis of the electrical impedance dependence on temperature and on damages outbreaks. The measurements are performed in controlled environment on a wide range of temperature and frequency. In some cases, the measured data show an impedance change due to the damage presence, which is of similar entity with respect to the variations caused by temperature. This may lead to misleading interpretations of impedance measurements in the absence of additional information. Hence the need of a proper temperature monitoring to possibly use electrical impedance spectroscopy analysis is required to unequivocally determine the health status of CFRPs.

This work focuses on the use of linear regression analysis-based machine learning for the prediction of the end of discharge of a prismatic Li-ion cell. The cell temperature was recorded during the cycling of Li-ion cells and the relation between the open circuit voltage (OCV) and cell temperature was used in the development of the linear regression-based machine learning algorithm. The peak temperature was selected as the indicator of battery end of discharge. A battery management system (BMS) using a pyboard microcontroller was constructed to monitor the temperature of the cell under test and was also used to control a MOSFET that acted as a switch to disconnect the cell from the circuit. The method used an initial 10 charge and discharge cycles at a rate of 1C as the training data, then another charge and discharge cycle for the testing data. During the test cycling, the discharge was continued beyond the cutoff voltage to initiate an overdischarge while the temperature of the cell was continuously monitored. When the temperature of the cell exceeded the predetermined threshold, the pyboard triggered the MOSFET to disconnect the cell and stop the overdischarge. The experiment was performed on three different cells, and the overdischarge for each was secured within 0.1 V of the cutoff voltage. The results of these experiments show that a linear regression-based analysis can be implemented to detect an overdischarge condition of a cell based on the anticipated peak temperature during discharge.

The microwave ablation technique to destroy cancer tissues in liver is practiced clinically and is the subject of ongoing research, e.g., ablation monitoring. For studies, liver tissue from cattle or pigs is often used as a substitute material. In this work, sweet potato is presented as an alternative material for microwave ablation experiments in liver due to similar material properties. Sweet potatoes as a substitute for liver have the advantages of better handling, easy procurement and stable material properties over time for microwave ablation experiments. The dielectric constant and electrical conductivity of sweet potato are characterized for temperature variation with the help of high-temperature dielectric probe. Furthermore, a test setup is presented for microwave ablation experiments in which a bowtie slot antenna matched to sweet potato is placed on its surface to directly receive the microwave power from a self-developed microwave applicator inserted into a sweet potato 4 cm below the surface antenna. A high-power source was used to excite the microwave powers up to 80 W and a spectrum analyzer was used to measure the signal received by the surface antenna. The experiments were performed in an anechoic chamber for safety reasons. Power at 50 W and 80 W was stimulated for a maximum of 600 s at the 2.45 GHz ISM band in different sweet potato experiments. A correlation is found between the power received by the surface antenna and rise of temperature inside sweet potato, relative received power drops from 1 at 76 ∘C to 0.6 at 88 ∘C (max. temperature) represents a 40% relative change in a 50 W microwave ablation experiment. The received power envelope at the surface antenna is between 10 mW and 32 mW during 50 W microwave ablation. Other important results for 10 min, 80 W microwave ablation include: a maximum ablation zone short axis diameter of 4.5 cm and a maximum ablation temperature reached at 99 ∘C, 3 mm away from the applicator’s slot. The results are compared with the state of the art in microwave ablation in animal liver. The dielectric constant and electrical conductivity evolution of sweet potato with rising temperature is comparable to animal liver in 50–60 ∘C range. The reflection loss of self-developed applicator in sweet potato is below 15 dB which is equal to reflection loss in liver experiments for 600 s. The temperature rise for the first 90 s in sweet potato is 76 ∘C as compared to 73 ∘C in liver with 50 W microwave ablation. Similarly, with 80–75 W microwave ablation, for the first 60 s, the temperature is 98 ∘C in sweet potato as compared to 100 ∘C in liver. The ablation zone short-axis diameter after 600 s is 3.3 cm for 50 W microwave ablation in sweet potato as compared to 3.5 cm for 30 W microwave ablation in liver. The reasons for difference in microwave ablation results in sweet potato and animal liver are discussed. This is the first study to directly receive a signal from microwave applicator during a microwave ablation process with the help of a surface antenna. The work can be extended to multiple array antennas for microwave ablation monitoring.

The temperature distribution during a metal casting process is important because it influences structural properties and residual stresses of the casted part. In this paper, we report on multipoint temperature monitoring based on a regenerated fiber Bragg grating (RFBG) array during a copper casting process, with a maximum temperature exceeding 1100°C. A temperature calibration function up to 800°C was obtained experimentally and was linearly extended to 1200°C. According to the experimental results, the temperature information from an RFBG temperature sensor agreed well with that from a thermocouple that was located close to the respective RFBG sensor element, even at temperatures above 1100°C. With the RFBG temperature sensor array in a single fiber, the temperature distribution and its temporal development were obtained, which can be used to better understand the copper casting process and improve the casting mold design.

Thermal ablation is achieved by delivering heat directly to tissue through a minimally invasive applicator. The therapy requires a temperature control between 50–100 °C since the mortality of the tumor is directly connected with the thermal dosimetry. Existing temperature monitoring techniques have limitations such as single-point monitoring, require costly equipment, and expose patients to X-ray radiation. Therefore, it is important to explore an alternative sensing solution, which can accurately monitor temperature over the whole ablated region. The work aims to propose a distributed fiber optic sensor as a potential candidate for this application due to the small size, high resolution, bio-compatibility, and temperature sensitivity of the optical fibers. The working principle is based on spatial multiplexing of optical fibers to achieve 3D temperature monitoring. The multiplexing is achieved by high-scattering, nanoparticle-doped fibers as sensing fibers, which are spatially separated by lower-scattering level of single-mode fibers. The setup, consisting of twelve sensing fibers, monitors tissue of 16 mm × 16 mm × 25 mm in size exposed to a gold nanoparticle-mediated microwave ablation. The results provide real-time 3D thermal maps of the whole ablated region with a high resolution. The setup allows for identification of the asymmetry in the temperature distribution over the tissue and adjustment of the applicator to follow the allowed temperature limits.