Modeling and measurement of a tissue-equivalent liquid for noninvasive dehydration sensing in the 2.45 GHz ISM-band

In this paper, a blood-equivalent liquid is presented. The phantom material at room temperature is a valid representation of blood at body temperature in the frequency range from 2 to 3 GHz with an maximum deviation of ±1.5 in e´ and ±2.8 in e". The effect of a hypertonic variation of the plasma hydration level has been modeled by varying the amount of water ±14 % in the tissue-equivalent fluid. Transmission based measurements have been performed on a tube phantom of PMMA with narrowband patch antennas on flexible substrates. The antennas have been placed at opposite sides of the phantom and measurements have been performed at different hydration levels of the substitute liquid. A clear distinction of the levels can be seen in both magnitude and phase of the transmission coefficient.