2020 Volume 58 Issue 1 Pages 47-53
We developed a non-contact device that measures the volume of body fluids using microwave transmission. This device detects the phase difference between the radio waves that pass through the measurement target and the radio waves that do not pass through. When the radio waves pass through the water, the phase of the radio waves is delayed. The change in water volume cause phase differences, and our proposed device measures the relative temporal change of congestion without restraint. Deep vein thrombosis is caused by hypercoagulability, stagnation of blood flow, and vascular endothelial dysfunction. Remaining in a seated position for prolonged periods of time may cause deep vein thrombosis due to the stagnation of blood flow and may result in death. This device measures the volume of body fluids in the lower limbs. If venous congestion can be detected, we believe that the device will be developed as a new preventive measure for deep vein thrombosis. In this study, a subject’s lower leg was compressed with a cuff at a pressure of 60mmHg for 5 min to induce venous congestion. We simultaneously measured the changes in phase difference and the changes in the outer diameter of the calf by our proposed device and a strain gauge. The results showed a strong correlation between the change in the phase difference and the change in the outer diameter of the calf. These findings suggest that the proposed device is able to measure the volume of body fluids without contact. Future work may explore the application of the device for measuring fluids in the lower body of individuals who sit for prolonged periods of time, including in e-sports.
