Zoya Popovic

Zoya Popovic is a Distinguished Professor of Electrical Engineering at the University of Colorado, Boulder. She obtained her Dipl.Ing. degree at the University of Belgrade, Serbia, and her Ph.D. at Caltech. She holds an honorary doctorate from the Carlos III University in Madrid. She was a Visiting Professor with the Technical University of Munich in 2001/03, ISAE in Toulouse, France in 2014, and was a Chair of Excellence at Carlos III University in Madrid in 2018/19. Prof. Popovic has graduated over 75 PhDs and currently advises 18 doctoral students. Her research interests are in microwave and millimeter-wave high-performance circuits for communications and radar, medical and industrial applications of microwaves, wireless powering and RF quantum sensing. She is a Fellow of the IEEE and the recipient of two IEEE MTT Microwave Prizes for best journal papers, the White House NSF Presidential Faculty Fellow award, the URSI Issac Koga Gold Medal, the ASEE/HP Terman Medal and the German Alexander von Humboldt Research Award. She is foreign member of the Serbian Academy of Sciences and Arts and was named IEEE MTT Distinguished Educator in 2013. She is a Fellow of the National Academy of Inventors and a Member of the National Academy of Engineering.

Title of keynote presentation:

Microwave Radiometry for Noninvasive Internal Body Temperature Measurements

Abstract:

There are a number of medical applications that require knowledge of internal body temperature [1], such as brain temperature monitoring during aortic repair open-heart surgery, monitoring athletes and soldiers under heavy physical training or during hypothermia, circadian cycle related sleeping disorders, determining type of strokes, and measuring temperature of tissues during cancer hyperthermia and ablation. Currently, there is no commercially available non-invasive passive and potentially wearable internal-body thermometer. Microwave radiometry can potentially solve this problem – this work focuses on the fundamentals of operation, design, implementation and testing of radiometers for internal temperature measurements of the human body. In this approach, the total blackbody power from a tissue stack is received by a near-field antenna placed on the skin connected to a low-noise receiver. Since human tissues are lossy at microwave frequencies, a relatively low frequency (between 1 and 3 GHz) is used for sensing temperature several centimeters under the skin [2].  The near-field antenna receives total noise power from all tissue layers and temperature retrieval for sub-surface tissue layers is performed using weighting functions, obtained by full-wave simulations with known tissue complex electrical parameters, combined with retrieval algorithms. Measurements are presented using several types of calibrated radiometers at 1.4GHz and 3GHz for various phantom tissues. In-vivo tracking in the human cheek is also shown to follow ground-truth thermocouple measurements [3]. With an integration time on the order of a second, temperature can be tracked within a fraction of a degree. Technical challenges include interference mitigation, variability of human tissues between people and parts of the body, limited spatial resolution and miniaturization. Some methods that address these challenge are: RFI cancellation by statistical processing; using reflectometry combined with signal processing for tissue calibration; multiple radiometers that use statistical methods to improve spatial resolution; and integrated radiometers in GaAs that reduce sensor size.

[1] S. Rossi, et al., “Brain temperature, body core temperature, and intracranial pressure in acute cerebral damage,” Journal of Neurology, Neurosurgery & Psychiatry, vol. 71, no. 4, pp. 448–454, 2001.

[2] P. Momenroodaki, et al., “Noninvasive internal body temperature tracking with near-field microwave radiometry,” IEEE T-MTT, vol. 66, no. 5, pp. 2535–2545, 2017.

[3] J. Lee, Z. Popovic, “A GaAs MMIC Correlation-Dicke Radiometer with Compact Antenna for Internal Body Thermometry,” IEEE JERM 2024,