Researchers have created a radio so tiny that almost seven would fit on the face of a penny. The device runs without a battery; instead it uses “power harvesting,” a process by which it recovers and uses energy from the same waves that carry signals to its antenna. Even if the radio chip did need a battery, a single AAA battery has enough power to run it for more than a century, researchers reported at the 2014 Symposium on VLSI Circuits Digest of Technical Papers. Many components of the radio had to be scaled down to fit onto the tiny silicon chip; the antenna, for example, is one-tenth the size of a Wi-Fi antenna—and yet, it runs at a fast speed of 24 billion cycles per second. The tiny radios cost only a few cents to manufacture, the researchers say, and such devices are key to the next wave of wireless devices; eventually they could link together gadgets like smart phones with everyday objects, which will then be able to make decisions with minimal human intervention.