Abstract:
RFID technology provides a foundation, an enabling technology towards the realization of ‘zero-power’ wireless sensors and implementing the Internet-of-Things (IoT) and machine-to-machine (M2M) communication. Interest in RFID technology is further enhanced by its fundamental capability for wireless powering of devices, allowing for batteryless operation. The presentation begins with an overview of energy considerations and challenges for low power system requirements in emerging applications such as health and smart homes, environmental monitoring, as well as an outlook of various energy harvesting technologies. The state-of-the-art in commonly used energy harvesting technologies such as solar, vibration, thermal and electromagnetic is then presented. Figures of merit are provided and emphasis is placed on design challenges and novel technologies and materials, such as paper, textiles, and inkjet printing. Special focus is placed on challenges associated with electromagnetic energy transfer and harvesting for range maximization of passive RFID systems. Rectenna design and optimization under different operating conditions and in different operating frequencies from HF to millimeter waves is addressed. Multiple technology harvesters leading to the development of energy harvesting assisted RFIDs are discussed. Low profile and conformal solar antennas and solar–electromagnetic harvesters including examples implemented on paper and textile substrates are presented. The integration of an antenna with a thermo-electric generator is demonstrated. Finally, waveform optimization in wireless power transfer is addressed, and the ability to improve the RF-DC power conversion efficiency of electromagnetic energy harvesting devices by tailoring the characteristics of the transmitted signals is discussed.