Temperature-sensitive Particles Research Articles

Design and Implementation of Temperature-sensitive Particle Temperature Measuring Structure in Microchannel

Any physical change or chemical reaction is closely related to temperature. Especially in the context of microscale continuous flow, the uniform temperature distribution affects the whole process of the reaction, so it is very important to detect the temperature in the microsystem. Temperature-sensitive particle temperature measurement is a kind of micro-scale non-contact temperature measurement. At present, the temperature-sensitive particle temperature measurement technology is mainly based on the direct design of experiments based on non-simulation. Starting from the microscopic point of view, this paper firstly analyzes the principle of fluorescence temperature measurement, establishes the consistency between the temperature-luminescence intensity relationship and the force-luminescence intensity relationship, and then uses the simulation software to build a microchannel temperature measurement model to analyze the temperature measurement effect of the selected temperature-sensitive particles. By comparing the Computational Fluid Dynamics (CFD) simulation results, the design of a non-contact particle temperature measuring structure inside the micro-channel is realized, which provides a feasible method in simulation.

Preparation of phase change microcapsules with high thermal storage and temperature sensitive for thermal management

Preparing microcapsules with core-shell structure by encapsulating phase change materials (PCM) in the shell is considered as an effective method to solve the leakage problem of PCM during use. Herein, a phase change microcapsule (MPCM) based on n-eicosane core and polyurea shell was prepared. This MPCM was prepared by interfacial polymerization of isophorone diisocyanate (IPDI) and ethylenediamine (EDA) using Pickering emulsion as a template and sulfonated lignin (SL) derived from industrial by-products as an emulsifier. The morphology, chemical structure and optimal preparation conditions of the MPCM were investigated by polarized light microscopy, fourier infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The results showed that the SL emulsified n-eicosane oil-in-water emulsion particles had good dispersion and homogeneous particle size. MPCM-2 with combined optimal conditions in MPCM exhibited regular spherical shape, high enthalpy of phase change (209.8 J/g), high encapsulation ratio (82.9 %), good thermal cycling stability, and negligible leakage rate. When PDMS and MPCM-2 were compounded and applied to thermal management, the MPCM-2/PDMS composite exhibited a much slower temperature rise and fall. Moreover, a plateau period appears at the crystallization and melting temperatures. Moreover, the phase change energy storage of MPCM/PDMS could be easily observed by the change of color after the introduction of temperature-sensitive particles. In summary, the present MPCM has good thermal storage and thermal management capabilities and provides a good application prospect for thermal energy storage systems.

High-strength, highly conductive and woven organic hydrogel fibers for flexible electronics

High conductivity, high strength and stretchability are important characteristics of flexible electronic materials. However, it is still a challenge that balancing the electrical conductivity and mechanical strength of materials. This paper proposes a simple method to embed hydroxyethyl cellulose (HEC) into polyvinyl alcohol (PVA) hydrogel to form large pores that can adsorb ions. The conductivity of the hydrogel immersed in the sodium chloride solution can reach 5.77 S/m, and the strength can reach 2.86 MPa when the strain is 400.30%. Then the hydrogel is soaked in a sodium chloride glycerin aqueous solution to prepare PVA-HEC organic hydrogel (PHOH) with both high strength and high conductivity at −30 and 65 °C. In order to meet the requirements of multiple sensors in the future, we added temperature-sensitive particles into the system to prepare fibers, which are used as woven temperature-sensitive conductive materials. Finally, we prepared a green energy source triboelectric nanogenerator (TENG) by the PHOH. This strategy is conducive to the self-powering, miniaturization and intelligence of flexible electronic materials.

Simultaneous measurement of temperature and flow distributions inside pendant water droplets evaporating in an upward air stream using temperature-sensitive particles

The containment spray system is an accident mitigation system used in nuclear reactors that reduces the high temperature and pressure generated inside the containment vessel during reactor accidents by condensing the steam and cooling the gas atmosphere. However, the heat and mass transfer mechanisms of flying spray droplets in a surrounding gas mixture have not yet been fully understood. To investigate these phenomena at a fundamental level, it is critical to obtain detailed temperature and flow distributions inside a water droplet as it descends. Currently, little experimental data has been reported detailing temperature and flow measurements inside water droplets, especially at the beginning of droplet evaporation, which contains highly transient exchange phenomena. In this study, the temperature and flow distributions were measured inside a 2-mm pendant water droplet during the initial period of its evaporation in an upward air stream using temperature-sensitive particles. Measurements were conducted once per 15 ms to determine variations in the droplet internal flow patterns and once per 0.1 s to determine the simultaneous temperature and flow characteristics. The flow distributions inside the droplets were measured using particle image velocimetry, and the temperature distributions inside the water droplets were measured simultaneously using the temperature-dependent phosphorescence decay constant. Droplet internal flow patterns were measured during a flow development period of 90 ms, the droplet internal flow development in a 20 °C air stream and 100 °C air stream were compared, and temperature and flow distributions were measured simultaneously inside evaporating droplets at different air stream temperature conditions within the first 1 s of droplet evaporation. The results indicated that the droplet internal flow development in a hot air stream is different than that in a room temperature air stream due to the Marangoni convection induced by the temperature gradient on the droplet surface under high temperature conditions. Owing to the resulting enhancement of heat and mass exchange within the droplets, the heat and mass transfer between the droplets and the surrounding gas can be influenced.

Ex situ calibration technique for simultaneous velocity and temperature measurements inside water droplets using temperature-sensitive particles

Phosphorescence-based temperature measurements usually employ in situ calibration in macro-scale flow domains. However, the application of conventional in situ calibration in millimetre scales such as in 2 mm droplets is difficult because temperature probing using an intrusive technique such as thermocouple-based measurement can deform a droplet interface and even its integrity. Therefore, in this paper we propose an ex situ calibration technique for combined 2D fluid temperature and flow velocity measurements inside pendant droplets using thermographic phosphorescence and particle image velocimetry. This calibration technique has the potential to perform measurements not only inside droplets but also in other small-scale fluid domains that are sensitive to intrusive temperature probing. To develop this technique, the effect of local phosphorescence intensity on the phosphorescence decay constant (initial intensity effect) was studied and quantified. We observed that the phosphorescence light intensity of the first image among the decay image series affects the local decay constants as the coefficient of a half sigmoid function. This novel ex situ calibration technique was used to investigate high-spatial-resolution temperature and flow velocity distributions inside a pendant water droplet located in an air stream, and an anti-distortion algorithm was used to correct the optical distortion induced by the curved surface of the droplet. The measured temperature and velocity fields were found to be reasonable and consistent with those obtained in previous studies. The proposed technique is expected to be useful in conducting further investigations on the mechanisms of heat and mass transfers between droplets and carrier gases. Furthermore, it can potentially improve our understanding of the heat and mass exchange mechanisms within a droplet’s internal flow structures and temperature gradients.

Intracellular trafficking of a pH-responsive drug metal complex

We previously developed a pH-responsive copper-doxorubicin (CuDox) cargo in lysolipid-based temperature-sensitive liposomes (LTSLs). The CuDox complex is released from the particle by elevated temperature; however, full release of doxorubicin from CuDox requires a reduced pH, such as that expected in lysosomes. The primary goal of this study is to evaluate the cellular uptake and intracellular trafficking of the drug-metal complex in comparison with intact liposomes and free drug. We found that the CuDox complex was efficiently internalized by mammary carcinoma cells after release from LTSLs. Intracellular doxorubicin and copper were 6-fold and 5-fold greater, respectively, after a 0.5h incubation with the released CuDox complex, as compared to incubation with intact liposomes containing the complex. Total cellular doxorubicin fluorescence was similar following CuDox and free doxorubicin incubation. Imaging and mass spectrometry assays indicated that the CuDox complex was initially internalized intact but breaks down over time within cells, with intracellular copper decreasing more rapidly than intracellular doxorubicin. Doxorubicin fluorescence was reduced when complexed with copper, and nuclear fluorescence was reduced when cells were incubated with the CuDox complex as compared with free doxorubicin. Therapeutic efficacy, which typically results from intercalation of doxorubicin with DNA, was equivalent for the CuDox complex and free doxorubicin and was superior to that of liposomal doxorubicin formulations. Taken together, the results suggest that quenched CuDox reaches the nucleus and remains efficacious. In order to design protocols for the use of these temperature-sensitive particles in cancer treatment, the timing of hyperthermia relative to drug administration must be examined. When cells were heated to 42°C prior to the addition of free doxorubicin, nuclear drug accumulation increased by 1.8-fold in cancer cells after 5h, and cytotoxicity increased 1.4-fold in both cancer and endothelial cells. Endothelial cytotoxicity was similarly augmented with mild hyperthermia applied prior to treatment with released CuDox. In summary, we find that the drug-metal complex formed in temperature-sensitive particles can be internalized by cancer and endothelial cells resulting in therapeutic efficacy that is similar to free doxorubicin, and this efficacy can be enhanced by elevated temperature.

Simultaneous measurement of temperature and velocity fields using thermographic phosphor tracer particles

A simple and inexpensive measurement system is suggested to measure the temperature and velocity fields simultaneously at high temperature using thermographic phosphor tracer particles. A 385-nm UV–LED and only one high-speed camera with a CMOS sensor were used for the simultaneous measurement system. The dispersion of a confined oil jet with high temperature was investigated to validate the system. The instantaneous temperature and velocity fields were obtained when silicon oil at 200 °C was injected into a silicon oil chamber at 25 °C. The decay-slope method was used for the temperature field analysis, and the velocity field was obtained by a two-frame cross-correlation algorithm. The velocity of the injected silicon oil rapidly decreased because of the change in viscosity of the silicon oil with temperature. The selection of an appropriate interrogation window size is suggested to take the moving distance of temperature-sensitive particles into account for accurate temperature measurement.

Visualization of the phase change behavior of sodium acetate trihydrate for latent heat storage

A latent heat storage system has higher storage capacity than a sensible heat storage system. Sodium acetate trihydrate has large latent heat at its melting point of 58 °C, which is suitable for a hot-water supply system. The crystal growth rate, convective flow and temperature fields during the phase change of sodium acetate trihydrate were quantitatively visualized using PIV analysis with temperature sensitive particles (TSPs) which has enabled a simultaneous measurement of the velocity and temperature fields. The velocity field was obtained by the PIV analysis of TSPs and the temperature field was simultaneously visualized from the intensity decay of TSPs. The visualized temperature of the solid–liquid multiphase flow increased slowly as crystals grew. The temperature around the crystal was lower than the melting temperature during the phase change process with the convection because the crystal was needle-shaped and a liquid phase was also present between crystals. After the convective velocity rapidly decreased due to the solidification, the temperature started to increase to around the melting point. Buoyancy-driven convection occurred under certain conditions of supercooling temperature and concentration of sodium acetate trihydrate. However, convection could not be fully developed over a certain range of concentration and supercooling temperature because the crystal growth rate was too fast and solidification was completed quickly.

Temperature nanotracers for fractured reservoirs characterization

Abstract Nanoparticle tracers are being investigated as a potential tool to measure temperature distributions in subsurface reservoirs. If the temperature distributions could be measured more precisely, this would greatly enhance the ability to estimate other reservoir properties, which would in turn inform reservoir engineering and field management decisions. Work toward two distinct but parallel objectives are described here. The first is to rank the informativity of various tracer candidates using modeling. The second is to develop temperature sensitive tracers experimentally, such that they would be capable of characterizing fracture properties and temperature distribution. The design of temperature-sensitive tracers is built around the design of the temperature sensing mechanism. In other words, the mechanism by which temperature is measured and the form and resolution of the resulting data, or response, have a profound impact on how informative that tracer can be about thermal breakthrough. Therefore, it is important to model the responses of candidate tracers in the context of an inverse problem to determine their relative informativity. In order to quantify tracer informativity for the simplified case in which the reservoir consists of a single parallel-plate fracture, one-dimensional analytical models were used to calculate the responses of four tracer types: conservative solute tracer, dye-releasing nanotracer, threshold nanoreactor, and temperature–time tracer (TTT). Inverse modeling was performed for various scenarios, and thermal breakthrough curves were calculated for each solution found. Tracers investigated in this study were found to perform very well, with small ranges of uncertainty for both thermal breakthrough forecasting and fracture property estimation. This was because the problem was highly constrained by defining the reservoir as a single fracture. For more realistic reservoir models consisting of complex fracture networks, it is expected that the uncertainty ranges would be larger and that all three temperature-sensitive tracers investigated here will outperform conservative solute tracers because their responses contain information about the temperature distribution. Experiments were performed to evaluate several potential nanosensor candidates for their temperature-sensitivity and to investigate particle mobility through porous and fractured media. Temperature-sensitive particles investigated in this study include the irreversible thermochromic, dye-attached silica and silica-protected DNA particles. A combined heat and flow test confirmed the temperature-sensitivity of the irreversible thermochromic particles by observing the color change. A detectable change in the fluorescent emission spectrum of the dye-attached silica particles upon heating was observed. The processing and detection of silica-encapsulated DNA particles with hydrofluoric acid chemistry was tested. A protocol to release the DNA by dissolving the silica layer without completely destroying the DNA was established. The silica-encapsulated DNA particles were flowed through a porous medium at high temperature. Some dissolution of silica particles was observed, leading to a reduction in their size. This research showed that synthesizing particles to respond to a specific reservoir property such as temperature is feasible. Using particles to measure reservoir properties is advantageous because particles can be transported to areas in the reservoir that would not be accessible by other means and therefore provide measurements deep within the formation.

Nanogels of Poly(N-Vinylcaprolactam) Core and Polyethyleneglycol Shell by Surfactant Free Emulsion Polymerization

Polymeric nanogels containing N-vinylcaprolactam (NVCL) and polyethyleneglycol methylether methacrylate (PEGMA) have been prepared by surfactant free emulsion polymerization. The influence of NVCL to PEGMA concentration ratio on the particle size and particle size distribution was studied. PNVCL:PEGMA nanogel particles exhibit thermal responsive properties in water and their transition temperature increases with higher content on PEGMA. It was found that the particle diameter decreased when higher amounts of PEGMA were used in the monomer mixture. The influence of the concentration and type of cross-linker: ethylene glycol dimethacrylate (EGDMA) or 3,9-divinyl-2,4,8,10-tetra-oxaspiro [5.5] undecane (DVA), on polymerization and colloidal characteristics of such temperature sensitive particles was studied. Nanogels, characterized by Fourier Transform Infrared Spectroscopy (FTIR) Differential Scanning Calorimetry (DSC), dynamic and static light scattering (DLS and SLS) and nuclear magnetic resonance spectroscopy (1H-NMR), showed higher incorporation of PEGMA than in the recipe, higher contraction by heating for bigger nanogels and spherical morphology.

Helical Colloidal Sphere Structures through Thermo‐Reversible Co‐Assembly with Molecular Microtubes

The co-assembly of spherical colloids and surfactant–cyclodextrin microtubes yields a library of dynamic colloid-in-tube structures, including helices. In situ observations of these structures, including their thermo-reversible assembly and disassembly, demonstrate the potential of the interplay between molecular and colloidal self-assembly, thereby providing a novel route to temperature-sensitive particle alignment and release.

先端可視化: Temperature Sensitive Particles

The instantaneous wall temperature was measured in an RCEM/engine cylinder, with or without the fire, by the phosphor thermometry. The measured wall temperature and its distribution had good correlation with a change of calculated gas temperature from the pressure. An oil flow and a gaseous flow in the cylinder were measured using a high speed camera, a single-pulsed UV laser and temperature sensitive phosphor particles. The temperature was calculated from the lifetime and the velocity was obtained from the phosphor particle images during a single decay. The temperature changes dependently on the crank angle agreed qualitatively with the gas temperature estimated from the pressure.

Combined two-dimensional velocity and temperature measurements of natural convection using a high-speed camera and temperature-sensitive particles

This paper proposes a combined method for two-dimensional temperature and velocity measurements in liquid and gas flows using temperature-sensitive particles (TSPs), a pulsed ultraviolet laser, and a high-speed camera. TSPs respond to temperature changes in the flow and can also serve as tracers for the velocity field. The luminescence from the TSPs was recorded at 15,000 frames per second as sequential images for a lifetime-based temperature analysis. These images were also used for the particle image velocimetry calculations. The temperature field was estimated using several images, based on the lifetime method. The decay curves for various temperature conditions fit well to exponential functions, and from these the decay constants at each temperature were obtained. The proposed technique was applied to measure the temperature and velocity fields in natural convection driven by a Marangoni force and buoyancy in a rectangular tank. The accuracy of the temperature measurement of the proposed technique was ±0.35–0.40°C.

Combined two-dimensional velocity and temperature measurements using a high-speed camera and luminescent particles

This paper proposes a combined method for two-dimensional temperature and velocity measurements using temperature sensitive particles (TSParticles), a pulsed ultraviolet (UV) laser and a single high-speed camera. TSParticles were synthesized using ion-exchange particles and Eu(TTA) luminescent dye. The size and material of the particles for synthesizing TSParticles are selectable. TSParticles respond to temperature changes in a flow and can also serve as tracers for the velocity field. TSParticles were seeded into a heated water flow in a complex-shaped channel constructed of MEXFLON resin, which has a refractive index exactly equal to that of water. Particle images of flow beyond the structure can be recorded without any distortion. The TSParticles were excited by the UV pulsed laser and the luminescence from the TSParticles were recorded at 40,000 frames per second as sequential images for a lifetime-based temperature analysis. Another advantage of our approach is that high time-resolved PIV can be carried out without a high-frequency laser. The recorded images were also used for the particle image velocimetry (PIV) calculation.

An Imaging-Driven Model for Liposomal Stability and Circulation

Simultaneous labeling of the drug compartment and shell of delivery vehicles with optical and positron emission tomography (PET) probes is developed and employed to inform a hybrid physiologically based pharmacokinetic model. Based on time-dependent estimates of the concentration of these tracers within the blood pool, reticuloendothelial system (RES) and tumor interstitium, we compare the stability and circulation of long-circulating and temperature-sensitive liposomes. We find that rates of transport to the RES for long-circulating and temperature-sensitive particles are 0.046 and 0.19 h(-1), respectively. Without the application of exogenous heat, the rates of release from the long-circulating and temperature-sensitive particles circulating within the blood pool are 0.003 and 0.2 h(-1), respectively. Prolonged lifetime in circulation and slow drug release from liposomes result in a significantly greater drug area under the curve for the long-circulating particles. Future studies will couple these intrinsic parameters with exogenous heat-based release. Finally, we develop a transport constant for the transport of liposomes from the blood pool to the tumor interstitium, which is on the order of 0.01 h(-1) for the Met-1 tumor system.

Combined measurement of velocity and temperature distributions in oil based on the luminescent lifetimes of seeded particles

The velocity field and temperature distribution in a fluid flow were measured simultaneously based on luminescence. PIV is useful for velocity measurement, and a measurement method based on the luminescent lifetime is appropriate for detecting the transient temperature field. However, there have been few reports on thermometry in the fluid flow by luminescence, whereas several studies have investigated surface temperature measurement. The europium complex (EuTTA) has been commonly used in temperature-sensitive ‘paints’ for several years and consequently has been examined in several papers. In the present study, particles doped with EuTTA, called temperature-sensitive particles (TSParticles), were prepared. The optical properties of the TSParticles were investigated. A TSParticle was found to be suitable for use with an optical sensor because its lifetime is very sensitive to temperature changes. The lifetime of the TSParticle was approximately 600 µs at 20 °C in water and the intensity was also large enough to be detected by a CCD camera without any image intensifier, at an exposure time of less than 60 µs. It was found that TSParticles could also be used for velocity measurement by means of the PIV technique. The temperature field was measured based on the decay ratio of the TSParticle images, and the velocity distribution in the same plane was also evaluated from these images by PIV. A demonstration was carried out in a thermal stratified silicone oil bath. The velocity and the transient temperature distribution of the oil flow were successfully measured. The spatial resolution of the temperature measurement in the demonstration was 60 µm. The uncertainty of the temperature was 0.35 °C. The spatial resolution and the uncertainty of velocity measurement were 0.6 mm and 20 µm s−1, respectively.

A222 燐光寿命を利用した流れの温度速度計測(燃焼科学と技術の新展開VI)

A simultaneous measurement technique of velocity and temperature distribution in a fluid flow was developed. Particle image velocimetry (PIV) was combined with a lifetime based scalar measurement technique. A measurement method based on the luminescent lifetime is appropriate for detecting the transient temperature field. Developed method needs a high speed camera, a laser (one excitation wave length) and temperature sensitive particles (TSParticles). The luminescence from TSParticles doped with EuTTA was detected by the high speed camera, which was not equipped with any image intensifier, at 15000 frames per second. Imaging at the high frame rate has a possibility to carry out PIV with a wide dynamic range. A decay of luminescent intensity was detected in detail. The decay curves at various temperature conditions were fitted well to exponential functions, from which the decay constant at each temperature was obtained. The proposed technique was applied to measure the temperature and the velocity field in a natural convection driven by Marangoni force and by buoyancy in a rectangular tank. The accuracy of the temperature measurement of the proposed technique was ±0.℃.

高速度カメラと燐光感温粒子を用いた寿命法による温度速度計測(流体工学,流体機械)

A simultaneous measurement technique of velocity and temperature distribution in a fluid flow was developed. Particle image velocimetry (PIV) was combined with a lifetime based scalar measurement technique. A measurement method based on the luminescent lifetime is appropriate for detecting the transient temperature field. Developed method needs a high speed camera, a laser (one excitation wave length) and temperature sensitive particles (TSParticles). The luminescence from TSParticles doped with EuTTA was detected by the high speed camera, which was not equipped with any image intensifier, at 15000 frames per second. Imaging at the high frame rate has a possibility to carry out PIV with a wide dynamic range. A decay of luminescent intensity was detected in detail. The decay curves at various temperature conditions were fitted well to exponential functions, from which the decay constant at each temperature was obtained. The proposed technique was applied to measure the temperature and the velocity field in a natural convection driven by Marangoni force and by buoyancy in a rectangular tank. The accuracy of the temperature measurement of the proposed technique was ±0.4℃.

Simultaneous 2D flow velocity and gas temperature measurements using thermographic phosphors

In this paper a new approach for simultaneous 2D velocity and temperature measurements using phosphoric particles is presented. The phosphoric particles respond to the temperature changes in the flow while acting as tracers for velocity mapping. The temperature sensitive particles were seeded into a heated flow and were excited by a pulsed UV laser. The subsequent red shifted emission was detected and analyzed to infer temperature using calibration procedures for lifetime and emission spectra against temperature. The diameter of the temperature sensitive particles, usually in the range of 1-10 mu m, makes them useful for velocity measurements using particle image velocimetry (PIV). As such, simultaneous measurement of temperature and flow velocity of a gaseous flow were performed and presented. (Less)

A104 TSParticleと寿命法によるオイル中の温度場計測

Phosphorescence and fluorescence are often applied to measure the temperature and the concentration of oxygen. The intensity and the lifetime of phosphor depend on the temperature and the oxygen concentration, due to the quenching effect of the phosphor. The present study clarified the effects of temperature on the lifetime of phosphorescence of Porphyrins, Ru(bpy)32+ and the europium complex. The phosphorescence lifetime of oil solution / water solution / painted wall were measured with changing temperature and oxygen concentration.In addition, the optical property of the small particles incorporated with the europium complex was investigated in the oil/water. The lifetime was strongly affected by temperature. Then, the temperature sensitive particle (TSParticle) with europium complex was applied to measure temperature in Silicone oil (10cSt) two-dimensionally.