Imagine having to listen to timeless Christmas songs using a tiny radio whose parts are only the size of atoms.
Researchers at Harvard's John A. Paulson School of Engineering and Applied Sciences (SEAS) have developed a biocompatible radio receiver using defects in pink diamonds as small as two atoms.
Despite its diminutive size, this new device is durable enough to withstand the effects of harsh environments, making it an ideal choice for making pacemakers and components for space probes.
World's Smallest Radio Receiver
To build the smallest radio receiver in the world, Marko Loncar and his colleagues at Harvard SEAS made use of the tiny defects in diamonds known as nitrogen-vacancy (NV) centers.
The researchers first had to replace a single atom of carbon in a diamond crystal using an atom of nitrogen and then remove another neighboring atom in order to produce an NV center. This was essentially done so that the team could create a hole right next to the nitrogen atom.
NV centers are often used to release single photons in objects or even detect faint magnetic fields. However, what the researchers wanted to utilize was the diamond components' photoluminescent properties, which would allow them to transform information into light.
Loncar and his team powered the electrons in the NV centers using the green light from a laser. Such electrons are highly reactive to electromagnetic fields including those produced by FM radio waves.
When an NV center is exposed to radio waves, it converts the signal and emits it in the form of red light. A photodiode can then be used to covert the resulting light into current, which in turn can be transformed into sound using headphones or radio speakers.
Electromagnets can be used to produce a magnetic field around the diamond strong enough to change the radio station. This allows the NV centers' receiving frequency to be tuned accordingly.
The researchers made use of billions of centers to make the radio's signal stronger. However, they found that a single NV center is capable of producing a single photon at a time instead light streams.
According to the developers, the Harvard radio benefits from the natural resiliency of diamonds, making it a very durable component. They were able to use the radio to play music at very high temperatures.
Loncar said their radio can be used even in harsh environments such as those in space. It can also be used inside the human body because of the biocompatible properties of diamonds.
The findings of the Harvard SEAS study are featured in the journal Physical Review Applied.
