ABSTRACT
This chapter describes the wireless identification and sensing platform (WISP), a wireless, battery-free platform for sensing and computation that is powered and read by standards-compliant ultrahigh frequency Radio frequency identification device (RFID) reader. It focuses on a next generation of WISP that is smaller than its predecessors and uses a new demodulator called the “multifunction harvester–demodulator” that reduces demodulator current leakage thus yielding improved range. The chapter presents the WISP design and power budget, followed by experimental results on range, and several representative applications, including several sensors and the RC5 cryptographic algorithm. The WISP analog front end differs slightly in purpose from that of conventional RFID tags. Due to the relatively high power consumption of WISP, the rectifier is designed to supply more current than ordinary tags. To communicate sensor data from WISP to a computer through an RFID reader, the data must be encoded into the tag identification number.
