Textile sensor for monitoring vital signs

In this paper, we describe the development of a textile-based design of the microwave coupler for vital signs monitoring and measuring changes in lung water contents. We also describe preliminary results from human clinical study using the developed textile coupler. Benchmarking results using an FDA approved medical device, Propaq LT and a blood pressure cuff, have shown the feasibility of accurately detecting the heartbeat and respiration rates as well as stroke volume from a single microwave measurement. Some of the design and implementation issues such as the coaxial feed and termination of the microwave sensor, contact with human skin issues, as well as the DSP algorithm for extracting the vital signs are discussed. Comparative results between reflection (single coupler) vs. transmission (two sensors), are also presented and discussed.