Time-response thermography after the application of a mild cold shock is considered a valuable diagnostic tool for breast tumor identification. The concept of this work is to estimate the depth of a malignant tumor based on the time-varying thermographic images after the applied cold shock. Specifically, the heat diffusion model is considered and a thorough numerical analysis reveals the significant temperature variation dependence to a malignant tumor existence. Then, the time-varying curves are approximated utilizing the powerful generalized pencil-of-function method, which leads to the robust extraction of the thermal time constant. The sensitivity of the latter is exceptional considering the detection of the tumor, while the deviation from the peak value provides a strong indication in terms of the tumor’s depth.
The core idea of the spectracoustic technique is the development and fabrication of a common probe for two modalities, the infrared spectroscopy and ultrasonic μTomography, for its application as a non-invasive analysis technique for tissue classification. The acquired and fused data from both modalities, provide a spectroscopic mapping tomographic image. The probe permits the excitation of the under-study object using both techniques simultaneously or in serial mode. Through the ultrasonic transducer of the probe, ultrasonic wave pulses are transmitted in the under-study tissue. Parallel to the path, used for the excitation of the piezoelectric transducer, a fiber optic bundle path is also designed in order to illuminate the under-study tissue. The reflected waves are transmitted back through the fiber optic bundle. The path used for emitting both the ultrasonics and infrared waves is filled with a special gel material in order for the ultrasonic probe to be coupled with the tissue. The infrared spectrum of this material is used as background spectrum form the infrared modality in order to be corrected from the acquired spectrum. By scanning a tissue in a specific region of interest, the incrementation of tomographic and spectroscopic data is achieved.
The dynamic breast skin temperature evaluation is investigated in the present work for the diagnosis of breast cancer at an initial stage. In particular, a realistic breast model, including a relatively small-sized tumor, is designed and thoroughly analyzed numerically in terms of the biological heat transfer equation. Initially, the skin surface temperature is measured for a steady-state scenario at normal conditions, indicating that a tumor behind the papilla corresponds to an almost physiological thermogram. For this reason, appropriate cooling stress is applied to capture the time-response of skin temperature throughout this procedure. Numerical results highlight that the contrast is enhanced thus facilitating an early diagnosis of breast cancer.
The efficient stimulation of a graphene microstrip plasmoni splitter via higher-order mode propagation is proposed in the current work. Initially, graphene waveguiding systems are investigated thoroughly in terms of the supported propagating modes and their potential excitation. Specifically, the microstrip apparatus is examined focusing on the distribution of bulk modes. This analysis indicates that the transition of a higher-order mode to a lower one is potentially smooth if an appropriately selected microstrip width is utilized. Consequently, an effective graphene plasmonic device is designed and stimulated via a higher-order bulk mode that equally splits the propagating surface wave to separated microstrips. The latter supports a lower-order mode and it is evaluated that the undesired back-reflected waves are minimized. Moreover, a thorough performance analysis is numerically conducted by means of a flexible Finite-Difference Time-Domain algorithm validating the remarkable functionality at a wide frequency range.
The purpose of the current paper is the development of a non-destructive imaging system for diagnostic purposes, consisting of ultrasonic transducers of high frequency and an infrared spectrometer, enabling the monitoring of the brain spatial variation and the detection of cancerous cells spreading to healthy tissues during the neurosur- gical tumor exception. Ultrasound utilization during the neurosurgery, where a part of the skull is temporarily removed, is able to provide a new perspective on the imaging techniques. The proposed device combines trans- ducers of different center frequencies in order to achieve sufficient penetration depth inside the brain and fine spatial resolution. Moreover, the infrared spectroscopy technique is utilized and combined with the ultrasound to achieve the recognition of the cancerous cells from their infrared fingerprint. The drawback of the poor penetration depth of the infrared electromagnetic waves is overcome by inserting a small diameter probe near the location of the main tumor. The probe is integrated into the same structure as the ultrasound device to receive both signals from the identical spot. Finally, advanced signal processing techniques are used to maximize separately the information of the independent systems, while the data fusion will be attempted.
The accurate and non-destructive estimation of the properties of coatings on metals via infrared spectroscopy is investigated in the present paper in order to inspect the traceability of the metals. First of all, the class of homogeneous coatings such as varnishes is examined, focusing on the extraction of the electrical properties and thickness through simple spectroscopic measurements. The thickness extraction originates from the multiple interferences that occur when an incident electromagnetic wave is reflected from a finite thickness layer via a procedure known as InfraRed Interference Method. The theoretical analysis is realized via the combination of fundamental electromagnetic and transmission line theories, while several measurements at the infrared region are conducted on varnishes with different electrical properties and thicknesses atop metals, in order to facilitate the accuracy of the proposed method. Moreover, the analysis is extended towards inhomogeneous materials such as highly absorbable pigments that are utilized to decrease efficiently the radar cross section of aircrafts. The Kubelka-Munk theory is utilized to estimate the scattering and absorbing properties of such materials. Additionally, various measurements and simulations are conducted on samples of different thicknesses to determine the penetration depth of infrared light and estimate the absorbing efficiency.
The present work investigates the propagation properties of the surface plasmon polariton wave supported on
graphene surface over an anisotropic substrate at far-infrared frequencies. Initially, the surface wave’s propagation
on isotropic media substrate is studied and verified with the theoretical estimation, including the noteworthy
epsilon-near-zero case. Moreover, after utilizing theoretical substrate media and examining anisotropy relative
to the normal to graphene’s surface, direction, the anisotropy is enforced to the tangential direction revealing
the significant influence of the substrate on the surface wave that is propagating on graphene. Additionally,
the more realistic implementation with graphene’s substrate consisting of metamaterial resonators is thoroughly
investigated. Numerical results are extracted through a reliable finite-difference time-domain (FDTD) algorithm,
focalising, mainly, on the wavelength of graphene’s surface wave.
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