An Empirical Measurement of Body Hydration using Galvanic Coupled Signal Characteristics

Galvanic coupled Intrabody communication signals use the human body as the waveguide. The signal characteristics change in gain and or loss by the body's physiological state. Because galvanic coupling contains the signal in the body, the technology can be suitable for nding alternative ap- plication in biomedical sciences. In this work, we inves- tigate the use of a galvanic coupling circuit to study the hydration status of a human body from the changes in the signal characteristics. We show that below 5 MHz conduc- tivity increases with hydration at the average rate of 0.24 dB/minute after uid restriction from night to 10 am. Dur- ing the process pre-hydration, hydration and post-hydration measurements were taken at 5, 10 and 15 minutes intervals. The measurements were taken after abstinence from uid as stated above. Prior measurements of conductivity were taken at the stated intervals before uid restriction as exper- imental control. Measurements of dehydration were taken after absorption has ceased and the subject urinated; it was observed that conductivity at dehydration decreased at the average rate of 0.92 dB/minute and the rate of hydration was quickest at 1.03 MHz while dehydration was fastest at 2.9 MHz.