An autonomous and energy efficient Smart Sensor Platform

A novel Wireless Smart Sensor Platform compatible with EPCglobal Class-1 Gen2 readers was developed. The platform is comprised of a five stage Dickson voltage multiplier, a dynamic impedance matching network (DyIMN), an XLP microcontroller (MCU) and an RFID tag IC with an embedded temperature sensor. Device range operations have been assessed up to a distance of 1.5 m from the RF source, corresponding to a minimum RF input power of -10 dBm. Firmware optimization leads to a reduction of power dissipation below 500nW in sleep mode, allowing an optimal energy harvesting and storage from the RF source. The harvested power enable logical operations to be completed from MCU, thus enabling sensing and storing of temperature measurements directly into the user memory of an RFID tag. Also the efficiency of the energy harvester is calculated from the MCU, hence tuning the DyIMN dynamically to respond over a wide range of input power and load impedance. The experiments demonstrate the feasibility of the system to operate autonomously within the reading range of a standard RFID reader, that acts both as RF power source and receiver of the data stored in the tag user memory.