Autonomous cars could benefit from cheap silicon-based sensors

Cars will eventually drive themselves and we are moving towards it gradually. But before autonomous technology is truly widespread, we have to solve several problems. Now scientists from the University of Waterloo and Chalmers University of Technology have managed to generate microwaves with inexpensive silicon, which will improve sensors used in autonomous cars.

Autonomous cars have a lot of expensive sensors – reducing their price would make autonomous technology more accessible. Image credit: Steve Jurvetson via Wikimedia (CC BY 2.0)

Microwaves are not just for cooking. High-frequency microwaves are useful in a huge variety of devices, such as police radars and collision-avoidance systems in cars. These microwaves are typically generated by devices called Gunn diodes, which do their job pretty well, but are quite expensive, because of use of expensive and toxic semiconductor materials such as gallium arsenide. Gunn diodes work using Gunn principle – a voltage is applied to gallium arsenide, which makes current flow through the material. But when voltage is increased, the current only rises to a certain point and then drops down – at that point semiconductor starts emitting microwaves.

Silicon is much cheaper than gallium arsenide, because it is the second-most abundant substance on earth. However, scientists have said for a long time that it is impossible to replicate the Gunn effect with silicone. But this is exactly what a team of scientists did – they used computational nanotechnology to show that the Gunn effect could be achieved with silicon. This technology would take advantage of silicon wires, one of which is 100,000 thinner than a human hair. Computer models showed that if nanowires were stretched at the time when voltage is applied to them, they would emit microwaves. You think the challenge would be to make silicon wires that thin? Not at all with today’s technology – nano-fabrication now allows making such complex tiny materials.

Of course, for now this invention is just a theory. Scientists would have to design a stretching mechanism and put together some prototypes for testing before we can really call it a win. C.R. Selvakumar, one of the authors of the study, said: “This is only the beginning. Now we will see where it goes, how it will ramify”.

We will have to wait and see where this research goes. If scientists are successful and the new device is cheaper than Gunn diodes, we will be able to say that we reached a breakthrough. Cheaper sensors could make autonomous cars a reality much quicker.


Source: University of Waterloo


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