NEAR INFRARED LIGHT HEATING OF SOFT TISSUE PHANTOMS CONTAINING NANOPARTICLES

The objective of this paper is to investigate the effect of the addition of nanoparticles to soft tissue phantoms, aiming at the enhancement of photothermal therapy for cancer. The phantoms were made of Polyvinyl chloride-plastisol (PVC-P), with two different nanoparticles, namely, titanium dioxide nanoparticles (TiO2) and silica nanoparticles (SiO2). A phantom without nanoparticles and a phantom containing a thermal paste were also manufactured for comparison purposes. The PVC-P phantom is transparent to the near infrared laser light, whereas the addition of titanium dioxide nanoparticles modified the optical properties enhancing the local heating, as demonstrated through experiments with a laser-diode and an infrared camera

Averaged field analysis for infrared images processing. Application to microscale thermal characterization

Abstract The focus of the present paper is devoted to the thermal conductivity measurement of microwires or microfibers inserted in an homogeneous subrstrate plate. Some steday and mainly 1D heat transfer conditions are applied to the plate. When the size of the object of interest is almost at the spatial resolution limit of the thermal imaging system, the corresponding heat transfer parameters to be measured in microscale devices can be adressed through the analysis of the deformation of a mainly one-dimensional temperature field. The small target to be analyzed can then be considered as a perturbating inclusion, yielding a two-dimensional deformation of the heat flux lines. This twodimensional field can be processed directly through a local (pixel-to-pixel) approach A direct local estimation of the pixel-to-pixel thermal conductances is then implemented, and deduced from the correlations between the Laplacian of the thermal signal and the corresponding first spatial derivatives. Unfortunately, in this case, the low signal-to-noise ratio makes the estimation procedure higlhy unstable. Moreover, estimation is only possible at the interface beween the different materials, that is through the thermal conductivity gradient. When only two components are considered in the thermal image, such as the case where a microwire is inserted in an homogeneous substrate, an alternative method is to use an analytical Twotemperature model approach [2] -[3], involving the averaged temperature of the two components derived from a simple energy balance approach, resulting in the following equation: These solutions are also compared to a full 3D numerical simulation in order to validate the application of the Two-temperature model for the corresponding experimental bench. Edge detection filtering is implemented in order to retrieve the boundaries of the sample. Then, some direct relationships involving the averaged temperatures are obtained and used directly in a linear estimation frame based on the maximum likelihood estimator. Some examples of experimental images processing are given in order to illustrate the suitability of the proposed model applied to the thermal conductivity measurement of microwires. I

Gravity inversion and uncertainty assessment of basement relief via Particle Swarm Optimization

Gravity inversion is a classical tool in applied geophysics that corresponds, both, to a linear (density unknown) or nonlinear (geometry unknown) inverse problem depending on the model parameters. Inversion of basement relief of sedimentary basins is an important application among the nonlinear techniques. A common way to approach this problem consists in discretizing the basin using polygons (or other geometries), and iteratively solving the nonlinear inverse problem by local optimization. Nevertheless, this kind of approach is highly dependent of the prior information that is used and lacks from a correct solution appraisal (nonlinear uncertainty analysis). In this paper, we present the application of a full family Particle Swarm Optimizers (PSO) to the 20 gravity inversion and model appraisal (uncertainty assessment) of basement relief in sedimentary basins. The application of these algorithms to synthetic and real cases (a gravimetric profile from Atacama Desert in north Chile) shows that it is possible to perform a fast inversion and uncertainty assessment of the gravimetric model using a sampling while optimizing procedure. Besides, the parameters of these exploratory PSO optimizers are automatically tuned and selected based on stability criteria. We also show that the result is robust to the presence of noise in data. The fact that these algorithms do not require large computational resources makes them very attractive to solve this kind of gravity inversion problems

Experimental study on thermal conductivity and viscosity of water-based nanofluids

Thermal conductivity and viscosity of deionized water-based TiO 2, SiO2, and Al2O3 nanofluids were investigated for various volume fractions of nanoparticles content and at different temperatures. A 3? technique was developed for measuring thermal conductivity of nanofluids. The theory and the experimental setup of the 3? measuring system is explained; a conductive wire is used as both heater and sensor in this system. At first, the system is calibrated using water with known thermophysical properties. Measured results showed that the effective thermal conductivity of nanofluids increases as the concentration of the particles increases but not anomalously as indicated in the majority of the literature and this enhancement is very close to the Hamilton-Crosser model; also this increase is independent of the temperature. The effective viscosities of these nanofluids increase by the increasing particle concentration and decrease with an increase in temperature, and cannot be predicted by the Einstein model. © 2010 Begell House, Inc

NEAR INFRARED LIGHT HEATING OF SOFT TISSUE PHANTOMS CONTAINING NANOPARTICLES

ABSTRACT The objective of this paper is to investigate the effect of the addition of nanoparticles to soft tissue phantoms, aiming at the enhancement of photothermal therapy for cancer. The phantoms were made of Polyvinyl chloride-plastisol (PVC-P), with two different nanoparticles, namely, titanium dioxide nanoparticles (TiO 2 ) and silica nanoparticles (SiO 2 ). A phantom without nanoparticles and a phantom containing a thermal paste were also manufactured for comparison purposes. The PVC-P phantom is transparent to the near infrared laser light, whereas the addition of titanium dioxide nanoparticles modified the optical properties enhancing the local heating, as demonstrated through experiments with a laser-diode and an infrared camera

Projet inter-régional Aquitaine-Midi-Pyrénées « thermique et μfluidique» : Galerie de champs de températures associés à la caractérisation thermique sur des puces μfluidiques

Projet inter-régional Aquitaine-Midi-Pyrénées « thermique et μfluidique» : Galerie de champs de températures associés à la caractérisation thermique sur des puces μfluidique

Near Infrared Light Heating of Soft Tissue Phantoms Containing Nanoparticles

International audienceThe objective of this paper is to investigate the effect of the addition of nanoparticles to soft tissue phantoms, aiming at the enhancement of photothermal therapy for cancer. The phantoms were made of Polyvinyl chloride-plastisol (PVC-P), with two different nanoparticles, namely, titanium dioxide nanoparticles (TiO2) and silica nanoparticles (SiO2). A phantom without nanoparticles and a phantom containing a thermal paste were also manufactured for comparison purposes. The PVC-P phantom is transparent to the near infrared laser light, whereas the addition of titanium dioxide nanoparticles modified the optical properties enhancing the local heating, as demonstrated through experiments with a laser-diode and an infrared camera