Date of Award
Electrical and Computer Engineering
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A MEMS-based microwave Pixel has been developed for use with an Ultra-wideband (UWB) radar probe for high-resolution 3-D non-contact, non-ionizing tomographic diagnostic imaging of the thorax. In the proposed system, an UWB radar transmits a 400 ps duration pulse in the frequency range of 3.1 GHz to 5.1 GHz. The transmitted pulse penetrates through the tissues and is partially reflected at each tissue interface characterized by a complex permittivity change. A suitable microwave lens focuses the reflected wavefront on a 2-D array of MEMS-based microwave Pixels to illuminate each Pixel to a tiny 2-D section of the reflected wavefront. Each Pixel with a footprint area of 595 x 595 μm2 is designed to have 144 parallel connected microfabricated inductors, each with an inductance of 12.439 nH, and a single 150 μm×150 μm microfabricated deformable diaphragm based variable capacitor to generate a voltage which is the dielectric signature of the respective tissue section. A 2-D array of such Pixels can be used to generate a voltage map that corresponds to the dielectric property distribution of the target area. The high dielectric contrast between the healthy and diseased tissues, enable a high precision diagnostics of medical conditions in a non-invasive non-contact manner. This thesis presents the analytical design, 3-D finite element simulation results, and a fabrication process to realize the proposed microwave imaging Pixel. The proposed Pixel with total inductance of 86.329 pH and capacitance tuning range of 1.68:1, achieved a sensitivity of 4.5 aF/0.8 μA.m-1 to generate tomographic coronal imaging slices of human thorax deep upto 4.2 cm enabling a theoritical lateral resolution of 0.59 mm.
Vejella, Sujitha, "A MEMS BASED MICROWAVE PIXEL FOR UWB RADAR BASED 3-D DIAGNOSTIC IMAGING" (2017). Electronic Theses and Dissertations. 7303.