Three-Dimensional Electromagnetic Torso Scanner.

A three-dimensional (3D) electromagnetic torso scanner system is presented. This system aims at providing a complimentary/auxiliary imaging modality to supplement conventional imaging devices, e.g., ultrasound, computerized tomography (CT) and magnetic resonance imaging (MRI), for pathologies in the chest and upper abdomen such as pulmonary abscess, fatty liver disease and renal cancer. The system is comprised of an array of 14 resonance-based reflector (RBR) antennas that operate from 0.83 to 1.9 GHz and are located on a movable flange. The system is able to scan different regions of the chest and upper abdomen by mechanically moving the antenna array to different positions along the long axis of the thorax with an accuracy of about 1 mm at each step. To verify the capability of the system, a three-dimensional imaging algorithm is proposed. This algorithm utilizes a fast frequency-based microwave imaging method in conjunction with a slice interpolation technique to generate three-dimensional images. To validate the system, pulmonary abscess was simulated within an artificial torso phantom. This was achieved by injecting an arbitrary amount of fluid (e.g., 30 mL of water), into the lungs regions of the torso phantom. The system could reliably and reproducibly determine the location and volume of the embedded target.

Half-sized cylindrical invisibility cloaks using double near zero slabs with realistic material size and properties.

A method is introduced to miniaturize invisibility cloaks by 50% using wave tailoring and finite/non-zero wave impedance of double near zero (DNZ) slabs. Unlike previous works, which use thick dielectric matching layers to miniaturize internal cloaks, the proposed technique is applied to both internal and external cylindrical cloaks using a thin and short DNZ slab to change cloaks' shapes to half-cylinder shells. Moreover, sets of structures are introduced for the half sized cloaks to enable using feasible-to-fabricate structures with the help of a rigorous theoretical analysis, which is validated via full-wave simulations. All of the presented results show that the proposed half cloaks can function perfectly well. The sensitivity of half-sized cloaks to the length and material properties of the DNZ slab is investigated to find the shortest length and the highest values of the permittivity and permeability for the slab to have small yet realizable structures. The analysis shows that slabs with length as small as the diameter of the cloaks and constitutive parameters (permittivity and permeability) as high asεslab=µslab=0.1-0.1iand εslab=µslab=0.05-0.04i for half-sized external cloaks and half-sized internal cloaks, respectively, can still considerably reduce the scattered fields. The effect of the loss and incident angle of the field on the performance of the miniaturized cloaks are also analyzed.

Wearable Electromagnetic Head Imaging System Using Flexible Wideband Antenna Array Based on Polymer Technology for Brain Stroke Diagnosis.

Given the increased interest in a fast, portable, and on-spot medical diagnostic tool that enables early diagnosis for patients with brain stroke, a new approach of a wearable electromagnetic head imaging system based on the polymer material is proposed. A flexible low-profile, wideband, and unidirectional antenna array with electromagnetic band gap (EBG) and metamaterial (MTM) unit cells reflector is utilized. The designed antenna consists of a 4 × 4 radiating patch loaded with symmetrical extended open-ended U-slots and fed by combination of series and corporate transmission lines. A mushroom-like 10-EBG unit cell arrays are arranged around the feeding network to reduce surface waves, whereas 4 × 4 MTM unit cells are placed on the back-side of the antenna to enable unidirectional radiation. The antenna is designed and embedded on a multilayer low cost, low loss, transparent, and robust polymer poly-di-methyl-siloxane (PDMS) substrate and optimized to operate in contact with the human head. The simulated and measured results show that the antenna has a fractional bandwidth of 53.8% (1.16-1.94 GHz), more than 80% of radiation efficiency, and satisfactory field penetration in the head tissues with a safe specific absorption rate. An eight-element array is then configured on 300 × 360 × 4.1 mm3 PDMS material covering an average human head size and used as a worn part of the imaging system. A realistic-shaped 3-D specific anthropomorphic mannequin (SAM) head phantom is used to verify the performance of the designed array. The imaging results indicate the possibility of using the designed conformal array to detect a bleeding inside the brain using a confocal image algorithm.