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Microwave imaging (MWI) systems are being investigated for breast cancer diagnostics as an alternative to conventional X-ray mammography and breast ultrasound. This work aims at a next generation of tissue-mimicking phantoms modelling the temperature-dependent dielectric properties of breast tissue over a large frequency bandwidth. Such phantoms can be used to develop a novel kind of MWI systems that exploit the temperature-dependent permittivity of tissue as a natural contrast agent. Due to the higher water content in tumor tissue, a temperature increase leads to a different change in the complex permittivity compared to surrounding tissue. This will generate a tumor dominated scattering response when the overall tissue temperature increases by a few degrees, e.g. through the use of microwave hyperthermia systems. In that case a differential diagnostic image can be calculated between microwave measurements at reference (around 37◦C) and elevated temperature conditions. This work proposes the design and characterization of agar-oil-glycerin phantoms for fatty, glandular, skin and tumor tissue. The characterization includes measurements with an open-ended coaxial probe and a network analyzer for the frequency range from 50 MHz to 20 GHz in a temperature-controlled environment covering the temperature range from 25◦C to 46◦C. The phantoms show an unique temperature response over the considered frequency bandwidth leading to significant changes in the real and imaginary part of the complex permittivity. Comparative studies with porcine skin and fat tissue show a qualitative agreement.

Doppler Ultrasound as the gold standard for noninvasive arterial pulsation monitoring has limitations such as dependency on the operator and absence of acoustic window in some patients. Recently, mm-wave has been propounded as an alternative modality for biomedical diagnostics. However, heartbeat monitoring using mm-wave modality has been experimentally investigated only for external carotid artery, and its usage for deeper arteries has not been proved, yet. This study investigates the feasibility of mm-waves in the monitoring of non-superficial arteries. A continuous-wave (CW) reflectometer sensor is used for sensing pulsations exploiting the Doppler effect. The artery mimicking tube passes through an artificial agar-oil skin phantom. A peristaltic pump circulates the liquid through a tube. An antenna is placed in direct contact with the phantom without any coupling liquid. First, we investigate the optimum frequency of the given antenna in its impedance bandwidth [16][17][18][19][20]. Using the optimum frequency, the pulsation of an artery with a 1.6 mm diameter, placed in the depth of 16 mm, and has less than 0.02 mm radial oscillation amplitude was easily detectable.