Smart Coat with a Textile Antenna for Electromagnetic Energy Harvesting

In the context of Wireless Body Sensor Networks (WBSN) for healthcare and pervasive applications, the wearable antennas offer the possibility of ubiquitous monitoring, communication, energy harvesting and storage. Textile antennas are the link for a non-invasive integration of communication equipment and sensors, boosting the garment as an interface that extends the communication system. The integration of electronic devices on clothing begs the question about how to feed them. The batteries are an obvious choice, but they are bulk, require frequent replacement or recharging and their finite lifetime has become a major ecological concern over the past years. Therefore, energy harvesting holds a promising future in the next generation of WBSN, where it will be possible to feed all its nodes without the need of replacement of batteries, thus creating auto-sustainable systems. Nowadays, as radio frequency energy is currently broadcasted from billions of radio transmitters (e.g. mobile communications and television/radio stations) it can be collected from the ambient. Responding to this context, this paper presents a smart coat with an embedded dual-band textile antenna for electromagnetic energy harvesting, operating at GSM 900 and DSC 1800 bands. The results obtained before and after the integration of the antenna into the garment are compared. Also, the influence of the user’s body in the antenna performance is analyzed. In free-space measurements this antenna shows 2dBi gain and efficiency 80%. The integration of textile antennas into smart clothing emerges as a particularly interesting solution when the replacement of batteries is not easy to practice.