An Electromagnetic Model of Human Vital Signs Detection and Its Experimental Validation

An electromagnetic model for heart rate and respiration rate detection using the scattered fields of incident plane waves on a dielectric model of a human subject has been developed. The model approximates the torso by an equivalent homogenous dielectric layer, and utilizes an accelerated parallel version of the multi-level fast multipole algorithm to speed up the computation. Non-contact measurements using an ultra-wideband radar are utilized to experimentally validate the model. The model proved to be accurate for both the heart rate and respiration rate detection within 5% error margin when compared with conventional contact sensor readings. The agreement between measured and simulated results is good for distances up to 3 m, and at various subject orientations with respect to the radar boresight. Meanwhile, in the presence of more than one subject, only slight degradation has been observed unless one subject is almost blocked by another. This accurate model would have broader impacts as it can be utilized to investigate various human activities and motion scenarios, and can be used, as well, to fine-tune the signal processing techniques and radar system development.