Over the last decade, plasmonic photothermal therapy (PPTT) has received significant attention as the new therapeutic strategy for the cancer therapy due to unique characteristics of the gold-nanoparticles. The characterization of the spatiotemporal heating potential for the gold nanorods (GNR) through mimicking PPTT process on the various conditions can help more quantitative approaches to treatment planning. The purpose of this study was to clearly understand the optical-thermal interactions between the laser, GNRs, and bio-tissues, and provide the information in clinical applications to implement the concept of heterogeneity, which can enable the optimization of treatment parameters for superficial breast cancer treatment.
Photothermal therapy (PT) provides a strong potential in treatment of tumors, selective cell death, through the ability of gold nanoparticles to target destructive heat preferentially to tumor regions. And yet, clinical application of the thermal therapies has not accomplished due to insufficient processes of the heating methods and temperature measuring techniques leading to low reproducibility of such treatment. In this study, we created a 3 dimensional tissue platform to characterize the heating method and to control the generated heat in the tissue used for a superficial cancer model using gold nanorods (GNRs) and near-infrared (NIR, 808 nm) laser. The 3D tissue platform involved a 2 mm wide hemisphere to confine the GNRs covered with20 μm thick polymer film designed to mimic localized nanoparticles in tumor. Moreover, this platform provides an easy way to measure heat distribution and temperature created in tumor cross section. To investigate the photothermal effect of GNRs on heat generation, the amount of GNRs and laser power density were controlled. The GNRs were shown to be the large absorption cross sections generating localized photothermal effects and hyperthermic effects on destructive consequences in the cell dynamics causing a partial tumor regression.
In this study, the evaluation method for the responsivity and noise characteristics of a commercial infrared thermal imaging camera and a custom-made sensor module was presented. Signal transfer functions (SiTFs) and noise equivalent temperature differences (NETDs) of the two sensor modules were obtained by using a differential mode blackbody that is able to control the temperature difference ΔT between an infrared target and its background. And we verified the suitability of our evaluation method through the comparison between the found NETD and the specification of the camera. In addition, the difference of 0.01 K of the two noise equivalent temperature differences calculated from with and without nonuniformity correction suggests that the nonuniformity correction is essential process for the evaluation of the infrared thermal imaging cameras. Finally, in case of the custom-made sensor module, only temporal NETD was found because of its higher nonuniformity characteristics.
A thermoreflectance microscopy (TRM) system has emerged as a non-destructive and non-contact tool for a high resolution thermal imaging technique for micro-scale electronic and optoelectronic devices. Quantitative imaging of the temperature distribution is necessary for elaborate thermal characterization under operating conditions, such as thermal profiling and performance and reliability analysis. We introduce here a straightforward TRM system to perform quantitative thermal characterization of microelectronics devices. The quantitative imaging of the surface temperature distribution of a polysilicon micro-resistor is obtained by a lock-in measurement technique and calibration process in the conventional CCD-based widefield microscope. To confirm the quantitative thermal measurement, the measured thermal information is compared to that obtained with an infrared thermography (IRT) system. In addition to quantitative surface temperature distribution, the sub-micron defects on microelectronic devices can be clearly distinguished from the thermoreflectance images, which are hardly perceptible with a conventional widefield microscopy system. The thermal resolution of the proposed TRM system is experimentally determined by measuring standard deviation values of thermoreflectance data with respect to the iteration number. The spatial and thermal resolutions of our system are measured ~670 nm and ~13 mK, respectively. We believe that quantitative thermal imaging in the TRM system can be used for improvement of microelectronic devices and integrated circuit (IC) designs.
We present a photothermal reflectance microscopy for detecting local defects inside optical films. This technique employs CCD-based thermoreflectance microscopy, which measures temperature-dependent optical reflectivity changes of materials. For photothermal imaging, an 808 nm CW laser beam with sinusoidal modulation is used to heat absorbing defects in the transparent optical film. The thermo-optic response resulting from the laser beam absorption of defects in the material yields a periodic alteration in the reflectivity around the defects. Such a time-varying thermoreflectance signal is probed with a 636 nm LED, and the amplitude of this signal is detected using a homodyne lock-in detection scheme, permitting enhancement of the defect contrast. The feasibility of the proposed imaging system is demonstrated on an optical material having absorbing inclusions, showing that the variation of the normalized optical reflections clearly reveals the local distribution of the submicron-sized defects buried in the optical material.
Cancer is increasing fast nowadays through all over the world. Early diagnosis of cancer is a desirable subject as it can
significantly improve the patient's chances of survival. In most cases the cancer is diagnosis using MRI, CT, PET. But,
there are several disadvantages associated with high cost, low sensitivity and specificity, and health risks from
radioactive. For that reason, significant efforts are being invested to improve the current imaging system.
Thermography can offer some advantages. Chief among these are the contact free and low cost for detect cancer. But
thermography has some disadvantages associated with low sensitivity for small tumors.
In this research develops non contact, safe, high sensitivity, and low cost infrared imaging technique. Experiments were
performed using lock in thermography with a small amount of magnetic nanoparticle (MNP) and radiofrequency
generator. As a result, highly sensitive infrared thermography can a small amount of MNP be detected by the technique.
We investigate the influence of oxide aperture size on the performance of intracavity contacted oxide-aperture vertical-cavity surface-emitting lasers with asymmetric current injection. Several counteracting mechanisms are shown to result in size dependent behavior, which limits the performance of very small cavities. Reducing the oxide aperture is shown to improve the threshold current and the 3dB bandwidth. However, significant increase of optical losses is observed that is attributed to increase the threshold current density and to decrease the maximum output power. From the far-field measurement, we have shown that the smaller aperture VCSELs have large FWHM. Also, we have achieved the small signal modulation bandwidth of 10.3GHz with 4.5μm oxide aperture diameter at 9mA bias current.
Intracavity-contacted resonant cavity enhanced photodetectors (IC RCEPDs) have been fabricated for monolithic integration with IC VCSELs. A low parasitic capacitance of 0.39 pF and an extrinsic 3-dB bandwidth of 9 GHz are demonstrated by using coplanar metal contacts. Optimization issues on device and epi designs are discussed. The largest frequency saturation photocurrent below which the extrinsic 3-dB bandwidth exceeds 6.5 GHz is 4.2 μA.
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