Microwave Characterization and Assessment of the Dielectric Properties of Normal Human Urine

The focus of this work is to study the dielectric properties of normal human urine as a foundation for future research, development, and effective clinical translation of microwave (MW) medical technologies. These properties are fundamental to the design and usage of these technologies, which are based on inherent dielectric contrasts for various types of diseases in order to image a region; detect a change or abnormality; or classify tissue state, grade, or stage. Currently available data on the dielectric properties of normal urine is extremely limited and highly inconsistent. No studies have examined the common handling confounders, such as time from voiding and temperature of the sample. Further, studies have not examined intraindividual and interindividual variability, nor is there any reported information whatsoever on sex-based differences in these properties. This work addresses these gaps in our fundamental knowledge and understanding of the dielectric properties of normal human urine. Specifically, in this work we: 1) characterize the MW dielectric properties of human urine across time (0–6 h postvoid), frequency (0.5–20 GHz), and temperature (22 °C–37 °C); 2) assess the effects of time and temperature on sample properties; 3) discuss variability at individual- and sex-levels; and 4) provide a temperature-dependent Debye model of normal human urine, including both frequency and temperature variables, to facilitate data reusability and sharing. In long-term, the outputs of this project will support the design, development, optimization, and translation of emerging and future MW medical technologies.