Single Antenna Bio-Sensing for Noninvasive Respiratory and Cardiac Activity Monitoring

The single antenna bio-sensing (SABioS) method is investigated for noninvasive respiratory and cardiac activity monitoring. Using an antenna sensor installed over the chest of a subject, the vital signs can be captured by analyzing changes in the antenna’s reflection coefficient due to two contributors, being the variations in the dielectric composition of the body and the structural deformations of the antenna due to thoracic expansion during the respiratory cycle. The operation principle of this method is elaborated and validated through simulations, and its agreement with a medical-grade reference device is studied via a preliminary experimental setup involving 14 volunteers. The results were analyzed using Bland-Altman analysis, linear regression, and various error metrics, and the maximum calculated mean absolute errors (MAEs) were 0.06 breaths per minute (bpm) for breathing rate (BR) and 0.14 s for inspiration/expiration time, demonstrating a strong agreement with the medical reference device. The article also briefly explores the potential of SABioS in cardiac monitoring and detecting breathing pauses, as well as its versatility in operating with different antenna types. The SABioS method provides a noninvasive, comfortable, and accurate solution for continuous vital sign monitoring without any dependency to external devices.