title: An IoT Reader for Wireless Passive Electromagnetic Sensors.
abstract: In the last years, many passive electromagnetic sensors have been reported. Some of these sensors are used for measuring harmful substances. Moreover, the response of these sensors is usually obtained with laboratory equipment. This approach highly increases the total cost and complexity of the sensing system. In this work, a novel low-cost and portable Internet-of-Things (IoT) reader for passive wireless electromagnetic sensors is proposed. The reader is used to interrogate the sensors within a short-range wireless link avoiding the direct contact with the substances under test. The IoT functionalities of the reader allows remote sensing from computers and handheld devices. For that purpose, the proposed design is based on four functional layers: the radiating layer, the RF interface, the IoT mini-computer and the power unit. In this paper a demonstrator of the proposed reader is designed and manufactured. The demonstrator shows, through the remote measurement of different substances, that the proposed system can estimate the dielectric permittivity. It has been demonstrated that a linear approximation with a small error can be extracted from the reader measurements. It is remarkable that the proposed reader can be used with other type of electromagnetic sensors, which transduce the magnitude variations in the frequency domain.
authors.affiliation: Department of Signal Theory and Communications, Universidad Carlos III de Madrid, Av. de la Universidad 30, 28911 Leganés, Madrid, Spain. ggalindo@tsc.uc3m.es.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Galindo-Romera
authors.affiliation: Department of Signal Theory and Communications, Universidad Carlos III de Madrid, Av. de la Universidad 30, 28911 Leganés, Madrid, Spain. jccano@tsc.uc3m.es.
authors.forename: Javier
authors.initials: J
authors.lastname: Carnerero-Cano
authors.affiliation: Department of Signal Theory and Communications, Universidad Carlos III de Madrid, Av. de la Universidad 30, 28911 Leganés, Madrid, Spain. jmartinez@tsc.uc3m.es.
authors.forename: José Juan
authors.initials: JJ
authors.lastname: Martínez-Martínez
authors.affiliation: Department of Signal Theory and Communications, Universidad Carlos III de Madrid, Av. de la Universidad 30, 28911 Leganés, Madrid, Spain. fjherraiz@tsc.uc3m.es.
authors.forename: Francisco Javier
authors.initials: FJ
authors.lastname: Herraiz-Martínez
keywords: Internet of Things; laboratory measurements; low-cost sensing system; passive electromagnetic sensor; permittivity measurements; portable sensing system; reader; split-ring resonator (SRR); wireless link