Etiqueta RFID passiva para monitoramento da frequência respiratória.

Abstract

Continuous monitoring of vital signals provides relevant information about a patient health status, which is essential in situations of risk. There is a need for practical and efficient systems to obtain these parameters and the RFID technology is presented in this work as a solution. In this work, a passive RFID tag is shown for respiratory rate monitoring. The tag eliminates the need for wires connected to the subject and provides comfort due to its flexibility. Simulations and measurements were performed. To carry out the simulations, it was necessary to characterize the dielectric materials. During these simulations, the reflection coefficient (S11), the resonance frequency and the impedance matching of the tag were observed. The principle of operation of the technology in this application is based on variations of the Received Signal Strength Indicator (RSSI) with the respiratory movements. In the result of the measurement with the tag in the subject, during which forced inhalations and slow expirations were made, these variations of the RSSI were noticed and, based on the respiratory cycles detected, it was possible to estimate the respiratory rate.