Microwave stethoscope (MiSt) as a low-cost vital signs sensor: Results from preliminary human subject studies

The MiSt measurement procedure for vital signs monitoring is based on the microwave reflection coefficient measurements on the patient chest using a novel microwave sensor. It is shown that MiSt provides integrated, multi-purpose, low-cost and non-invasive vital signs sensor that is capable of measuring heart-rate, respiration rate, changes in the lung water content, and the heartbeat waveform. In this paper, the improved microwave sensor design is presented. Human experiments are also conducted in clinical settings and comparisons with commercial FDA approved medical devices (Propaq LT) are given, thus, demonstrating the feasibility of MiSt in accurately detecting multiple VS. According to the human subject experiment results and its comparison with the Propaq data, the accuracy of the MiSt in measuring multiple VS including heart rate (HR), respiration rate (RR), and EKG has been established. Additional measurement capability of the lung water content is an important and unique asset of the proposed MiSt system. These experimental results clearly demonstrate the advantage of extracting multiple VS parameters using only single microwave measurement and make the MiSt a promising technology for implementation of the proactive healthcare delivery methods.