Moore's law is a key factor in an ambient radio frequency (RF) energy-harvesting project from researchers at the Intel Research Seattle Lab. At the recent Rawcon Conference in San Diego, Intel's Joshua Smith presented a paper that discussed the scavenging of 60 microwatts from a TV tower 4.1 kilometers away from the lab. The power was used to drive a thermometer/hygrometer and its LCD. The approach harvested enough energy to drive many Wireless Identification and Sensing Platform (WISP) applications. The researchers call RF scavenging Wireless Ambient Radio Power, and presented it as another WISP application. A WISP is essentially an RF identification (RFID) tag with a microcontroller on it, according to Smith. He says the increase in integration and decline in power consumption of digital circuitry has led to the improved functionality per microwatt of scavenged energy. "The range at which you can power a device [with a given amount of ambient RF energy] should double every four years," he says. The two power-harvesting techniques of RFID and TV could lead to a perpetual sensing platform that does not need batteries.
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