Oct 14, 2019 | |
The nano-guitar string that plays itself(Nanowerk News) Scientists at Lancaster University and the University of Oxford have created a nano-electronic circuit which vibrates without any external force. |
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Using a tiny suspended wire, resembling a vibrating guitar string, their experiment shows how a simple nano-device can generate motion directly from an electrical current. The research has been published in Nature Physics ("A coherent nanomechanical oscillator driven by single-electron tunnelling"). | |
To create the device, the researchers took a carbon nanotube, which is wire with a diameter of about 3 nanometres, roughly 100,000 times thinner than a guitar string. They mounted it on metal supports at each end, and then cooled it to a temperature of 0.02 degrees above absolute zero. The central part of the wire was free to vibrate, which the researchers could detect by passing a current through it and measuring a change in electrical resistance. | |
Just as a guitar string vibrates when it is plucked, the wire vibrates when it is forced into motion by an oscillating voltage. This was exactly as the researchers expected. | |
The surprise came when they repeated the experiment without the forcing voltage. Under the right conditions, the wire oscillated of its own accord. | |
The nano-guitar string was playing itself. | |
Lead researcher Dr Edward Laird of Lancaster University said: “It took us a while to work out what was causing the vibrations, but we eventually understood. In such a tiny device, it is important that an electrical current consists of individual electrons. The electrons hop one by one onto the wire, each giving it a small push. Usually these pushes are random, but we realised that when you control the parameters just right, they will synchronise and generate an oscillation.” | |
So what note does the nano-guitar play? | |
“The nanotube is far thinner than a guitar string, so it oscillates at much higher frequency – well into the ultrasound range so no human would be able to hear it. | |
“However, we can still assign it a note. Its frequency is 231 million hertz, which means it’s an A string, pitched 21 octaves above standard tuning.” | |
The nano-oscillator could be used to amplify tiny forces, such as in novel microscopes, or to measure the viscosity of exotic quantum fluids. |
Source: University of Lancaster | |
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