Cardiopulmonary signal sensing from subject wearing body armor.

Continuous wave (CW) Doppler motion sensing radar can detect human physiological signal such as respiration or heart signals at a distance and through barriers. It has been shown that heart rate can be extracted with good accuracy for normally clothed subjects. Such technique could potentially be used to search for survivors in battlefield triage applications. To assess the feasibility of such applications, we investigated Doppler radar of cardiopulmonary signal sensing from subjects wearing body armor vests. This paper presents measurement results of heart signals obtained using CW Doppler radar from a subject wearing body armor vest. Since armor plate reflects most of the RF signal, received signal after reflected from a subject is phase modulated with motion of an armor plate induced by chest motion, rather than directly with chest motion due to cardiopulmonary motion. Two different cases, including supine and seated positions, are chosen for this study, and good sensitivity was obtained in both cases. To the best of author's knowledge, this is the first published result of cardiopulmonary signal detection from a subject wearing a body armor vest.