Engineers develop world’s first nano-FM radio transmitter

A team of engineers from Columbia Engineering in the US have developed a nano-mechanical system that generates FM signals. This transmitter is the first of its kind and is the smallest FM radio receiver that is made out of graphene. This substance was first discovered in 2004 and scientists have been amazed with its unique electronic and mechanical properties. This carbon-based material is credited for its high electrical conductivity and exceptional strength.

Graphene is a single atomic layer of carbon and the strongest material that’s capable of tuning the output frequency of a custom oscillator. Its properties are more enhanced than silicon making it the ideal substance for micro-electromechanical systems. The researchers at Columbia Engineering tested graphene’s mechanical capability to create a voltage controlled oscillator (VCO) which is the electronic component used to generate FM signals. The transmitter they created was able to oscillate at a frequency of 100 MHz. The research team used low-frequency music signals to modulate 100 MHz carrier signal from their graphene nanomechanical system (NEMS) and managed to recover the signals again by utilising an ordinary FM receiver.

They tested the vibrational qualities of the device at room temperature in a vacuum chamber. They did this by first adjusting the signal gain and using a variable amplifier at the resonance frequency. Then the output was connected to the gate, the closed loop amplified thermal vibrations and made the device oscillate.

James Hone, Mechanical Engineering professor at Columbia Engineering, commented: “This work is significant in that it demonstrates an application of graphene that cannot be achieved using conventional materials. And it's an important first step in advancing wireless signal processing and designing ultra-thin, efficient cell phones. Our devices are much smaller than any other sources of radio signals, and can be put on the same chip that's used for data processing. This device is by far the smallest system that can create such FM signals.’’

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These micro transmitters can be used in accelerometers and gyroscopes in smartphones. The advantage that graphene transmitters have over conventional radios is that it is very compact and can be turned over a wide range.

The engineers are now working to find out how to put the device directly onto integrated circuits that contain the necessary readout circuitry and drive. Efforts are also being made to reduce the noise from the oscillators and at scaling down graphene’s elementary version to make it more adaptable for smartphones. 

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