RFID-based vital signs monitoring

Radio-Frequency Identification (RFID) technology has been widely used in various application such as logistics, localization, tracking, and activity recognition. In this chapter, we introduce some existing works on vital signs monitoring using RFID systems such as respiration monitoring, and heart rate monitoring, among others. We focus on our work of respiration monitoring using RFID systems. Respiration monitoring helps assess health conditions and guide the treatment of chronic diseases. However, current respiration monitoring techniques are either cumbersome or cause inconvenience to users in practice. To address the problem, we propose to monitor users' breathing using commercial-off-the-shelf (COTS) RFID systems. In our system, passive, lightweight RFID tags are attached to users' clothes and reflect incoming radio signals, and commodity RFID readers measure reflected radio waves from users. We track periodic body movement due to inhalation and exhalation by analyzing the low-level data reported by commodity readers. To enhance the measurement robustness, we synthesize data streams from an array of multiple RFID tags to improve the monitoring accuracy. Our design follows the standard EPC protocol that arbitrates collisions in the presence of multiple tags. The experiment results show that the prototype system can simultaneously monitor breathing with high accuracy, even in the presence of multiple users.