Scientists Build World’s Smallest Radio Receiver

A team of researchers has built the world's smallest radio receiver, featuring building blocks the size of two atoms.

The researchers from Harvard's School of Engineering and Applied Sciences used atomic scale defects in pink diamonds to create not only the smallest radio receiver in the world but the toughest. It can withstand harsh conditions, which could be useful in exploring tough environments.

Aside from that, it is biocompatible, meaning it could work anywhere from a probe on Venus to even a pacemaker for the heart.

Radios are made of five basic components -- a power source, a transducer, a tuner, a speaker and a receiver. The receiver is the part that collects electromagnetic signals, so they can be sent to the transducer to turn them into a current.

Imperfect Pink Diamonds

The researchers have used imperfect pink diamonds as part of the smallest radio receiver. These man-made defects are called nitrogen-vacancy centers (NV centers). The scientists replaced a single carbon atom in the diamond with a nitrogen atom. An adjacent atom is also removed completely. As a result, the nitrogen atom would have a hole in it.

Green Light

In the new device, electrons in diamond NV centers are pumped by green light emitted from a laser. When these NV centers receive radio waves, they convert them and emit the audio signal as red light. Thus, a photodiode will convert light into a current and then convert unto sound via a small speaker.

The durability of the diamond makes the radio resilient. In fact, the researchers were able to play music at temperatures of 660 degrees Fahrenheit and above.

"Diamonds have these unique properties," Marko Loncar, the Tiantsai Lin Professor of Electrical Engineering at SEAS, said in a press release. "This radio would be able to operate in space, in harsh environments and even the human body, as diamonds are biocompatible," he added.

The study was published in the journal Physical Review Applied.