Thermoelectric Generator

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Background Despite recent gains in turn-on sensitivity, passive RFID tags are approaching fundamental limits imposed by diode conversion of RF-to-DC power. However, an RF-to-thermal-to-DC energy conversion process can be shown to outperform existing diode conversion techniques at very low power levels. Technology Dr. Gregory Durgin from the School of Electrical and Computer Engineering at Georgia Tech has explored the original design of an RF-driven thermoelectric generator and demonstrate a possible pathway to a purely passive tag with greater than 100m range. This thermodynamic analysis on RF-to-DC energy conversion indicates that state-of-the-art energy-harvesting circuitry is not operating anywhere close to the fundamental physical limits of these processes. Furthermore, at low RF voltage and power levels, a solid-state RFTG device is predicted to outperform the state-of-the-art energy-harvesting circuits at 915 MHz in terms of efficiency and output voltage for RF inputs of -30 dBm or less. This RFTG illustrates the benefits of considering RF energy harvesting techniques that are not all-electrical in nature. In our age of limitless nanotechnological devices and micro electro-mechanical machines (MEMS), other exotic forms of RF-to-DC conversion with non-electrical intermediary forms may exist which have similar benefits to the RFTG. Applications Such a device, whether used as an energy-harvester or passive RF detector –could enable numerous new battery-less devices for emerging internet of things applications.