Emerging RFID technology lets us embed sensor units into a very small chip, creating a wireless sensing device. The authors bring together an embedded temperature sensor unit and passive RFID circuitry in a single-chip solution for future commercial smart sensors. This fully integrated CMOS batteryless device measures temperature and performs calibration to compensate for the sensor's inherent imperfections. An RF link using passive RFID's backscattering technique wirelessly transmits the data to a reading device while extracting power from the same "airwave," letting the device operate anywhere and last almost forever. The entire microchip, including the temperature sensor, consumes less than a few microamperes over a half a second, thus allowing the scanning device to capture data from a longer read distance.

This article is part of a special issue on RFID Technology.