Thermal Probe Research Articles

Research on Liquid Flow Measurement Method Based on Heat Transfer Method

Thermal flowmeters are used more and more widely in liquid flow measurement. In this paper, the mechanical shape of the thermal flowmeter is designed, and the optimal installation position of the thermal probe is determined. In the aspect of measurement mechanism research, three heating methods of the thermal probe are deduced: constant voltage heating method, constant current heating method, and constant power heating method. After reasoning, the constant current heating method is determined to be ideal, so the constant current heating method is selected to heat the speed-measuring probe in the experiment. By analyzing the power factor of convection heat transfer and residual heat source of the heating probe, it is concluded that the measurement range of the thermal flowmeter is 0.5–15 m3/d, the flow in this range is proportional to the electrical signal, and the relative error of measurement is within ±5.8%. According to the analysis of the experimental results, the thermal flowmeter has a simple mechanical structure and no redundant moving parts, which can prolong its service life when used on site. When considering industrial applications, the error may be greater than the laboratory error.

Achieving Mild Therapeutic Hypothermia in the Human Cochlea.

To determine temperature and duration of cooling necessary for achieving cochlear mild therapeutic hypothermia (MTH) via ear canal cooling using cool water and earmold attached to a Peltier device. Human temporal bone lab study performed at the University of Mississippi Medical Center. Cochlear cooling via the ear canal using water irrigation and an earmold attached to a Peltier device. Temperature analysis through implanted thermal probes within the cochlea. Temperature changes in the cochlea. Irrigation of the ear canal with water resulted in achieving MTH in approximately 4 minutes using cool water (30°C) and in approximately 2 minutes using ice-chilled water. After 20 minutes, irrigation of the ear canal using cool water plateaued at a ∆2°C while cooling with ice-chilled water results in an average ∆4.5°C. We observed MTH using a medium-length earmold attached to a Peltier device after approximately 22 minutes of cooling and achieved a maximal average ∆ of 2.3°C after 60 minutes of cooling. Finally, we observed that a longer earmold (C2L) with greater proximity to the eardrum resulted in more efficient intracochlear temperature change, achieving MTH in approximately 16 minutes. MTH of the cochlea can be achieved with water-based ear canal irrigation and via a Peltier device connected to an aluminum earmold.

Temperature limits during irradiation in laser-assisted treatment of peri-implantitis - labo-ratory research

Peri-implantitis is a relatively new and difficult disease that is becoming more common. Of the different therapeutic options to manage this condition, lasers show certain advantages over other therapeutic alternatives because of their antibacterial potential. The aim of the present study was to investigate the temperature rise of implant surfaces, soft tissues, and bone during irradiation with diode, CO2, and Er:YAG lasers. Ten implants inserted in biological models were irradiated with three laser systems with different parameters: a diode laser (980nm) with power levels of 0.75W and 1.6W; a CO2 laser (10600nm) with power levels of 252W and 241W; and an Er:YAG laser (2940nm) with power levels of 1.5 W, 6.8 W, and 7.5 W. The temperature rise was measured using a specially designed thermal probe (type K thermocouple) with accuracy of ±0.1°C over the range from 20°C to 80°C. The temperature was measured at 5 points - in the implant body, in the mucosa, in the middle part of the implant, in the implant apex, and in the bone around the implant apex. Measurements were obtained at 1 minute working interval. Diode and CO2 lasers with both parameters used increased significantly the temperature of more than 46°C, whereas the temperature in the Er:YAG laser group was less than 30°C. There was a statistically significant difference between diode, CO2, and Er:YAG lasers in favor of the erbium laser. The Er:YAG laser demonstrates the best thermal properties during irradiation of the implant surface. The three working modes tested - 1.5W, 6.8W, and 7.5W - provide safe intervention on both the soft and bone tissues of the implant interface and on the implant itself.

Nanoscale Thermal Strain Engineering-Driven Ferroelastic Domain Evolution in CH3NH3PbI3 Perovskites.

A local thermal strain engineering approach via an ac-heated thermal probe was incorporated into methylammonium lead triiodide (MAPbI3) crystals and acts as a driving force for ferroic twin domain dynamics, local ion migration, and property tailoring. Periodically, striped ferroic twin domains and their dynamic evolutions were successfully induced by local thermal strain and high-resolution thermal imaging, giving decisive evidence of the ferroelastic nature in MAPbI3 perovskites at room temperature. Local thermal ionic imaging and chemical mappings demonstrate that domain contrasts are from local methylammonium (MA+) redistribution into the stripes of chemical segregation in response to the local thermal strain fields. The present results reveal an inherent coupling among local thermal strains, ferroelastic twin domains, local chemical-ion segregations, and physical properties and offer a potential path to improve the functionality of metal halide perovskite-based solar cells.

Thermophysical Properties of Bentonite–Sand/Fly Ash-Based Backfill Materials for Underground Power Cable

The surrounding (backfill) materials around the underground power cable systems are essential for dissipating the heat away from it, during the exertion phases. The heat dissipation restrains the thermal instability and risk of progressive drying of the backfill materials, thus reducing the thermal stress on the power cable. Thermal instability indicates the reduction in thermal properties (conductivity or diffusivity) due to the migration of moisture because of heat accumulation. Thus, the backfill materials should have adequate thermal properties and water retention capacity to transfer the heat from the heat source to the surrounding area with minimal moisture migration. The bentonite has high water retention capacity, but low thermal conductivity, whereas sand/fly ash exhibits low water retention and has higher thermal conductivity than bentonite. The addition of bentonite promotes the water holding capacity and thermophysical properties of sand and fly ash. Therefore, this study presents the thermal properties of backfill materials, bentonite–fly ash (B–F) and bentonite–sand (B–S), at varying weight-percent of sand and fly ash with bentonite. Various compositions of the mixtures were compacted to varying dry densities, and water contents and thermal properties variation of backfill materials were measured using a dual thermal needle probe ‘KD2 Pro’ at room temperature. The study deals with the systematic evaluation of the volumetric specific heat capacity, thermal conductivity, and diffusivity of backfill materials against varying dry density and water content. The threshold water content (TWC) has been determined from the thermal diffusivity–water content variation curve, and it has correlated with plastic limit (PL) and optimum moisture content (OMC). Thereafter, the efficacies of two thermal conductivity prediction models have also been evaluated statistically with respect to experimental results.

Spectral tuning of Bloch Surface Wave resonances by light-controlled optical anisotropy

Abstract Fostered by the recent advancements in photonic technologies, the need for all-optical dynamic control on complex photonic elements is emerging as more and more relevant, especially in integrated photonics and metasurface-based flat-optics. In this framework, optically-induced anisotropy has been proposed as powerful mean enabling tuning functionalities in several planar architectures. Here, we design and fabricate an anisotropic two-dimensional bull’s eye cavity inscribed within an optically-active polymeric film spun on a one-dimensional photonic crystal sustaining Bloch surface waves (BSW). Thanks to the cavity morphology, two surface resonant modes with substantially orthogonal polarizations can be coupled within the cavity from free-space illumination. We demonstrate that a dynamic control on the resonant mode energies can be easily operated by modulating the orientation of the optically-induced birefringence on the surface, via a polarized external laser beam. Overall, reversible blue- and red-shifts of the resonant BSWs are observed within a spectral range of about 2 nm, with a moderate laser power illumination. The polymeric structure is constituted by a novel blend of an azopolymer and a thermally-sensitive resist, which allows a precise patterning via thermal scanning probe lithography, while providing a significant structural integrity against photo-fluidization or mass-flow effects commonly occurring in irradiated azopolymers. The proposed approach based on tailored birefringence opens up new pathways to finely control the optical coupling of localized surface modes to/from free-space radiation, particularly in hybrid organic–inorganic devices.

Quantitative Characterization of Local Thermal Properties in Thermoelectric Ceramics Using "Jumping-Mode" Scanning Thermal Microscopy.

Thermoelectric conversion may take a significant share in future energy technologies.Oxide-based thermoelectric composite ceramics attract attention for promising routes for control of electrical and thermal conductivity for enhanced thermoelectric performance. However, the variability of the composite properties responsible for the thermoelectric performance, despite nominally identical preparation routes, is significant, and this cannot be explained without detailed studies of thermal transport at the local scale. Scanning thermal microscopy (SThM) is a scanning probe microscopy method providing access to local thermal properties of materials down to length scales below 100 nm. To date, realistic quantitative SThM is shown mostly for topographically very smooth materials. Here, methods for SThM imaging of bulk ceramic samples with relatively rough surfaces are demonstrated. "Jumping mode" SThM (JM-SThM), which serves to preserve the probe integrity while imaging rough surfaces, is developed and applied. Experiments with real thermoelectric ceramics show that the JM-SThM can be used for meaningful quantitative imaging. Quantitative imaging is performed with the help of calibrated finite-elements model of the SThM probe. The modeling reveals non-negligible effects associated with the distributed nature of the resistive SThM probes used; corrections need to be made depending on probe-sample contact thermal resistance and probe current frequency.

Cutaneous thermosensory mapping of the female breast and pelvis

Differences in skin thermal sensitivity have been extensively mapped across areas of the human body, including the torso, limbs, and extremities. Yet, there are parts of the female body, such as the breast and the pelvis for which we have limited thermal sensitivity data. The aim of this study was to map cutaneous warm and cold sensitivity across skin areas of the breast and pelvis that are commonly covered by female underwear. Twelve young females (21.9 ± 3.2 years) reported on a 200 mm visual analogue scale the perceived magnitude of local thermal sensations arising from short-duration (10 s) static application of a cold [5 °C below local skin temperature (Tsk)] or warm (5 °C above local Tsk) thermal probe (25 cm2) in seventeen locations over the breast and pelvis regions. The data revealed that thermal sensitivity to the warm probe, but not the cold probe, varied by up to 25% across the breast [mean difference between lowest and highest sensitivity location was 51 mm (95% CI:14, 89; p < 0.001)] and up to 23% across the pelvis [mean difference between lowest and highest sensitivity location: 46 mm (95% CI:9, 84; p = 0.001)]. The regional differences in baseline Tsk did not account for variance in warm thermal sensitivity. Inter-individual variability in thermal sensitivity ranged between 24 and 101% depending on skin location. We conclude that the skin across the female breast and pelvis presents a heterogenous distribution of warm, but not cold, thermal sensitivity. These findings may inform the design of more comfortable clothing that are mapped to the thermal needs of the female body.

Different transpiration and growth patterns of the black locust plantation and natural oak forest on China's Loess Plateau

AbstractRestoration of natural secondary forests and afforestation of introduced tree species are major effective measures for revegetation. The semiarid Loess Plateau region, characterised by fragile ecosystems and severe soil erosion, is a key area for ecological restoration and protection in China. To illustrate water use characteristics and adaptation to drought in the main forests in this area, we monitored the xylem sap flow of two typical adjacent forest communities with similar climatic characters, a secondary natural forest dominated by oak (Quercus liaotungensis) and a pure plantation of black locust (Robinia pseudoacacia), during 2011–2019 using Granier‐type thermal dissipation probes. Solar radiation (RS), air temperature, relative humidity (RH), precipitation and soil water content (SWC) were measured simultaneously. Throughout the whole study period, the mean diameter at breast height (DBH) and total sapwood area increased by 4.5 cm and 1.10 m2 ha−1, respectively in the oak forest and by 1.0 cm and 0.22 m2 ha−1, respectively in the black locust plantation. The monthly stand transpiration was jointly determined by phenological and meteorological factors. At the annual timescale, transpiration of the oak stand was significantly correlated with potential reference evapotranspiration (ET0) and rainfall in the previous year, whereas a significant positive relationship was detected between stand transpiration and SWC in the black locust stand. The analyses of differences between dry and wet years showed that the oak forest exhibited significantly different parameters in the regression analysis of stand transpiration to vapour pressure deficit (VPD), whereas only one parameter was clearly distinct in the black locust plantation, suggesting that its transpiration status did not fully recover even in wet years. The management of black locust plantations with weakened growth conditions should be adjusted under prolonged drought conditions. In contrast, oak forest can maintain the water balance and stable growth by efficiently controlling stomatal behaviour.

Development and application of a novel pre-drilling thermal probe in-situ testing equipment

At present, the in-situ testing equipment used for measuring the thermophysical properties of rock and soil is scarce. Based on the working principle of the pressuremeter and ground heat exchanger, a pre-drilling thermal probe in-situ testing equipment is developed. This novel developed pre-drilling thermal probe in-situ testing equipment includes thermal probe, pressure control system, temperature control system, integrated conversion control device, and coaxial pressure pipe connection pipeline. A three-dimensional heat transfer model was established to simulate the heat transfer between the thermal probe and surrounding ground. Based on the principle of the temperature dissipation and numerical simulation, a calculation method for the thermal conductivity of rock and soil with pre-drilling thermal probe is proposed. Laboratory model tests of the sand under dry and saturated conditions were conducted. The deviation values for the thermal conductivities of sand under dry and saturated conditions measured by the designed pre-drilling thermal probe and thermal conductivity tester are 0.037 and 0.026 W/m·°C, respectively. Thus, the reliability of utilizing the new pre-drilling thermal probe testing equipment to measure the thermal conductivity of the soil is confirmed. The field test of utilizing this new pre-drilling thermal probe testing equipment to measure the thermal properties of the soil was performed. The results show that because the soil layers are in undisturbed state during the test process, the pre-drilling thermal probe testing equipment can truly reflect the inherent thermal properties of different soil layers.

Developing compact tuning fork thermometers for sub-mK temperatures and high magnetic fields

There is a growing demand for experiments on calorimetric and thermal transport measurements at ultra-low temperatures below 1 mK and high magnetic fields up to 16 T. Particularly, milligram-sized solid samples are of great interest. We present the development of scalable thermometers based on quartz tuning fork resonators immersed in liquid 3He and adapt hydrodynamic models to provide an improved description of temperature dependence in the high viscosity regime between 1 and 10mK. We demonstrate successful thermometer operation and discuss the feasibility of fast and compact thermal probes suitable for small samples.

Near-infrared light-triggered nitric oxide nanocomposites for photodynamic/photothermal complementary therapy against periodontal biofilm in an animal model.

Background: Periodontal disease, an oral disease that initiates with plaque biofilm infection, affects 10% of the global population. Due to the complexity of tooth root anatomy, biofilm resistance and antibiotic resistance, traditional mechanical debridement and antibiotic removal of biofilms are not ideal. Nitric oxide (NO) gas therapy and its multifunctional therapy are effective methods to clear biofilms. However, large and controlled delivery of NO gas molecules is currently a great challenge. Methods: The core-shell structure of Ag2S@ZIF-90/Arg/ICG was developed and characterized in detail. The ability of Ag2S@ZIF-90/Arg/ICG to produce heat, ROS and NO under 808 nm NIR excitation was detected by an infrared thermal camera, probes and Griess assay. In vitro anti-biofilm effects were evaluated by CFU, Dead/Live staining and MTT assays. Hematoxylin-eosin staining, Masson staining and immunofluorescence staining were used to analyze the therapeutic effects in vivo. Results: Antibacterial photothermal therapy (aPTT) and antibacterial photodynamic therapy (aPDT) could be excited by 808 nm NIR light, and the produced heat and ROS further triggered the release of NO gas molecules simultaneously. The antibiofilm effect had a 4-log reduction in vitro. The produced NO caused biofilm dispersion through the degradation of the c-di-AMP pathway and improved biofilm eradication performance. In addition, Ag2S@ZIF-90/Arg/ICG had the best therapeutic effect on periodontitis and NIR II imaging ability in vivo. Conclusions: We successfully prepared a novel nanocomposite with NO synergistic aPTT and aPDT. It had an outstanding therapeutic effect in treating deep tissue biofilm infection. This study not only enriches the research on compound therapy with NO gas therapy but also provides a new solution for other biofilm infection diseases.

Prospective thermal probes for Lunar soil properties studying

Prospective thermal probes for Lunar soil properties studying

Unlocking the organic residues preserved in the corrosion from the Pewsey Hoard vessels.

The characterization of archaeological metal corrosion has traditionally been limited to the identification of inorganic compounds usually by X-ray diffraction (XRD), thought to result from the interaction between the metal object and the deposition environment. The discovery of a hoard of Late Roman copper-alloy vessels in Wiltshire, UK presented an unique opportunity to adopt a multi-analytical approach to characterize corrosion combining XRD with Fourier-transform infrared(FTIR) and gas chromatography with quadrupole time-of-flight mass spectrometry using a thermal separation probe (GC-QTOF-MS with TSP). This approach revealed organic compounds potentially historical preserved within crystalline inorganic matrices. It has been known for some time that ceramics can harbour organic residues, which provide crucial evidence about the use of these vessels in the past. Our results confirms that similar residues appear to survive in metal corrosion thus extending the potential for identification of biomaterials used in the past.

Extended Thermal Probe Method for Measuring Thermal Stability of Soils Surrounding Buried Power Cables

The single most influential factor in determining the rating of underground cables is the thermal resistivity of the soil that surrounds the cables. An accurate measurement of soil thermal resistivity is therefore critical to the determination of cable ratings. Ratings are also strongly influenced by the thermal stability of the soil, because heat generated by the cables can often drive soil moisture away from the cables resulting in an unexpected steep rise in the soil resistivity and a corresponding sharp reduction in cable ratings. Soil thermal stability can be determined by a simple, short-duration test that involves a thermal probe that has traditionally been used to measure thermal resistivity if the duration of the test is extended. Therefore a single test with a thermal probe can be employed to provide a measure of the soil's thermal stability as well as its thermal resistivity. Armed with knowledge of both resistivity and stability of the soil, a utility engineer can confidently calculate cable ratings that will result in safe cable operating temperatures even under the most adverse unstable soil conditions. Measurements of soil stability are shown to be influenced by the soil's properties, the heat generated in the cables, the diameter of the cable/soil interface and the duration that the soil experiences heating by the cables. Experimental measurements of soil stability using the extended probe method are demonstrated for four different soils, and measurements of stability are shown to influence the rating of several different cable installations.

High-efficiency Low-cost Smart IoT Agriculture Irrigation, Soil's Fertility and Moisture Controlling System

The world's population increased exponentially and more food is required to support the growing population. However, the existing agriculture solutions are too costly for small-scale farmers. This has motivated us to design a Smart IoT Agriculture System (SIAS) to monitor and control the soil's moisture and fertility levels. SIAS is a low-cost Internet of Things (IoT) solution that used an online app to monitor and control water consumption and the soil's fertility level. ESP8266 microcontroller is used in SIAS to automatically control the irrigation system that consists of a soil moisture sensor, thermal probe, and water pump. The pH sensor is used to monitor the soil's fertility level. The data collected from the IoT sensors are uploaded to the ThingSpeak cloud database through WiFi. Blynk app is used to control the SIAS on the smartphone. The prototype development, implementation details and the optimal operation condition of SIAS are reported in this paper. SIAS with a total cost of USD46 is proven to have lower water consumption (85% lower), real-time monitoring of the soil's fertility and a better crop growth rate compared to the existing conventional watering timer system.

Analysis of transient heat conduction within semi-infinite medium surrounding heated conical shell

The probe method is an in-situ method used for measuring the thermal properties of the surrounding medium. The conical probe is a new configuration, which still lacks heat transfer analysis. To obtain a model of the conical probe configuration, we investigate the temperature evolution within and around the conical probe, allowing for contact thermal conductance between the conical shell and the surrounding medium. The governing differential equations written in a special coordinate system are obtained by considering a differential element of the conical shell and balancing heat energy. Assuming that the heat flux component parallel to the surface of the conical shell can be neglected, we simplify the equations. The solution of the simplified model is obtained by Laplace transforms. This solution is verified based on the comparison between the present analytical results and numerical computations with the finite element method (FEM). We discuss the causes of errors, including the neglected ed heat flux component, axial and radial boundaries and non-ideal heat source. The analytical solution of the simplified model is well fitted in the regions where boundary effects can be neglected. In this study, a material selection guideline for conical probes different from cylindrical thermal probes is proposed. The analytical solution presented greatly reduces the computation time and has strong potential for solving the inverse problem.

Calibration of Thermal Dissipation Probes for Xylem Sap Flow in the Wood of a Diffuse-Porous and a Conifer Species under Cyclic Heating

The most popular sap flow measurement technique uses thermal dissipation probes. Differences in wood characteristics and the natural temperature gradient between probes have affected the accuracy and applicability of the sap flow equation. In addition, the continued heat of the probe can also cause thermal damage to tree tissue. The objectives of this study were to use cyclic heating and calibrate the probes with two species: Pinus bungeana Zucc. And Salix matsudana Koidz., two typical diffuse-porous species. This experiment evaluated a thermal dissipation probe in three heating modes: continuous heating, 10 min heating and 50 min cooling (10/50), and 30 min heating and 30 min cooling (30/30). The heating modes were evaluated on two species. Temperature differences between the heating needle and the control needle under different heating modes and transpiration water consumption (whole-tree weighing method) were observed simultaneously. The sap flow estimation equation under cyclic heating mode was established by analyzing the relationship between the sap flow rate and the values obtained from whole-tree weighing. The results showed that the original equation underestimated sap flow rate of P. bungeana and S. matsudana by 67% and 60%. Under the cyclic heating modes, the modified equations were different from the original equation, and their accuracy was improved. After verification, the corrected equations [Fd = 0.0264K0.738 (P. bungeana, 30/30, R2 = 0.67), Fd = 0.0722K1.113(S. matsudana, 30/30, R2 = 0.60), Fd is the sap flow density, K is temperature coefficient] reduced the influence of the natural temperature gradient on the estimation of sap flow rate, thereby significantly improving the accuracy of sap flow rate estimation. The resulting equation may be more suitable for actual field observations of sap flow in the two tested species. The cyclic heating mode has the potential to measure plant transpiration for extended periods in the field.

Recovery of Microbes from Subsurface Europa Analog Environments: An Efficient Mechanical-Thermal Probe for Collecting Biological Samples from the Subsurface of Icy Moons.

The ultra-low temperatures (<173K) and ultra-low pressures (<0.1 Pa) that exist on the surface of icy moons present a formidable challenge for collecting biological samples. Standard drilling technology is not efficient in these conditions, where conduction of thermal energy leads to the possibility of freezing in place and shear forces impart a strenuous test on microbial viability. If microbes exist within the first few meters of the surface, an extraction process must be gentle enough to recover them intact. This report describes a substantial improvement from the study by Davis in 2017, who presented a concave conical thermal probe capable of penetrating -65°C ice in 1000 Pa pressure. The current report describes a mechanical-thermal device for penetrating ≤ -150°C ice in 10 Pa pressure, which is analogous to the physical conditions on the surface of icy moons. The mechanism has an efficiency of >68% with -65°C ice and >61% with -150°C ice, which is well above the expected 10-15% for a Philberth-type probe. In addition, the probe can harvest a sensitive bacterium (Escherichia coli) from under a layer of acidified peroxide ice (pH 1.1), which is analogous to the expected surface chemical composition of the icy moon Europa. In field tests at -20°C air and -6°C ice temperatures, multiple organisms were extracted in a viable state, and chemical analysis indicated high-resolution separation of stratified layers. Finally, attaching the thermal tip to a telescopic mechanism allowed the probe to penetrate through 1.0 m of -65°C ice, which is well below the depth of harmful radiation expected at the subsurface of Europa. The current work opens the door for a lander vehicle to penetrate the upper subsurface of Europa and analyze biologically active samples.

Preparation and Near‐Infrared Photoelectric Properties of n‐Type Cu3P

AbstractAs intrinsic cuprous phosphide (Cu3P) shows p‐type conductivity, the investigation of n‐type Cu3P (n‐Cu3P) was lacking and hindered its development and application. In this paper, novel n‐type conducting cuprous phosphide (n‐Cu3P) has been prepared by annealing ZnO/Cu3P/Cu structure. The morphology, composition and structure of the thin films were characterized by field emission scanning electron microscopy (FSEM), energy dispersive X‐ray spectrometer (EDX), X‐ray diffraction spectroscopy (XRD) and laser Raman spectroscopy (Raman). The semiconductor conduction type was analyzed by thermal probe method and Hall coefficient method. The transition of conduction type from p‐type to n‐type occurred as ZnO/Cu3P/Cu was annealed at 550 °C. The growth mechanism of n‐Cu3P was discussed. Finally, the infrared absorption and photoelectric properties were investigated. The near‐infrared photoelectronic performance of Cu3P was reported for the first time. The successful preparation of n‐Cu3P is helpful to promote the research and application of Cu3P based electronic devices.