Multiparameter electromagnetic sensor for AAL indoor measurement of the respiration rate and position of a subject

In this paper, a new electro-magnetic sensing system for the indoor measurement of respiration rate and subject position is presented. The measurement system has been especially conceived for use in Ambient Assisted Living (AAL) applications; therefore, a specifically designed, radiation element has been designed and realized in order to be easily installed at home. The measurement principle is based on the measurement of the reflection coefficient S11 which is operated when a frequency sweep signal is transmitted by the radiation element placed in front of the subject. S11 values are related to the distance from the reflecting object (the subject) and can be consequently related to his/her respiration activity and position. A mathematical description of the algorithm for the extraction of the aimed information, the experimental set-up and some results, obtained in a real scenario (private apartment), are reported. These results clearly show the ability of the proposed sensing system to detect the presence of the subject, to measure the respiration rate and to determine his/her position within the observed environment. The proposed solution presents therefore most of the required features in order to be used for home monitoring and AAL applications.