Chipless RFID Sensors for Wearable Applications: A Review

Radio frequency identification (RFID) is a quickly growing innovative wireless data capturing technology for automatic identification, product tracing, security investigation, automatic toll fee, vehicle tracking, and e-Health. Wearable sensing technology and on-body structures have achieved pervasive responses due to their fabulous potential in the Internet of Things (IoT), healthcare, and smart homes. Inexpensive chipless RFID tags for on-body sensing are the upcoming research for such wearable devices. Its sensing skill offers the unified real-time monitoring of vital signs. This paper reviews various chipless passive RFID tag sensors for wearable applications. The main goal of this research work is to study the basics of chipless RFID sensors and their working principles. Further, chipped RFID sensors are very costly for mass implementation. Hence, chipless tag sensors have grown into a cost-effective and maintenance-free substitute, fulfilling the requirements of the society for the emergent technologies, where lots of these sensors can be used. Understanding the importance in emerging applications, essential materials needed for different sensors, basic circuit models for chipped and chipless sensors, and challenges with limitation of recent chipless RFID sensors are also discussed in this article.