TV, radio, GPS, cell phones, wireless Internet and other electronics all use different radio waves to receive and send information. Now scientists at MIT have created a tiny antenna capable of receiving any radio signal, based on the human ear.
The new universal radio could lead to better reception and a new class of electronics that can pick up any radio frequency.
"The human ear is a very good spectrum analyzer," said Rahul Sarpekhkar, a professor at MIT who co-authored the paper in the June issue of the IEEE Journal of Solid-State Circuits. "We copied some of the tricks the ear does, and mapped those onto electronics."
The unique architecture of the human ear allows it to detect a wide range of sounds. A spiral with thousands of tiny hairs, called cilia, of different sizes help the ear to separate out each frequency, from 100 hertz up to 10,000 hertz, and transmit that information to the brain.
To detect electromagnetic waves instead of pressure waves the MIT scientists used circuits, in place of cilia. Starting on the outside edge of the 1.5-mm by 3-mm-chip are tiny squares, each one corresponding to a different size radio wave.
As they spiral into the center, the squares become larger and larger. The outer spiral detects the highest energy, shortest frequency waves, while the center circuits detect less energetic, longer frequency waves.
The universal radio might be inspired by the human ear, but in terms of spectrum range that can be detected, the EM ear outperforms the human by about a million to one. The electromagnetic ear detects this huge range of frequencies using the same amount of energy that a typical cell phone does.
"A simple cell phone takes 300 milli volts to detect one carrier wave," Sarpekhkar said. "We can do all 50 carrier frequencies with 300 milli volts."
Other devices do exist that can examine a range of radio frequencies. They just require much more power to do so. The low power usage of the electromagnetic ear means it would be ideal for portable electronic devices. The MIT team has a patent on their chip but so far doesn't have firm plans to commercialize the technology.
The first use of a universal radio, say the scientists would be to eliminate any noise in the signal. Cell phone breaking up? The chip could switch to a nearby and less cluttered wavelength. Same for snowy TV sets and slow wireless Internet, or inaccurate GPS signals.
In the future, a cell phone equipped with such a chip could easily pick up TV programs, songs on the radio, and virtually all other radio transmissions.
A chip that can receive virtually any radio signal is good. A device that can also transmit on any frequency would be even better. Adding more power to the device can achieve this, and the MIT scientists are still working on it, but for now, creating a universal radio that receive any signal is still impressive.
"It's very interesting just to see that it's possible to do this," said Christopher Shera, a doctor at the Massachusetts Eye and Ear Infirmary.
"People have tried to construct electronic cochlea before, but this is the first demonstration that imitates the amplification we think happens in the ear to produce a device that works."
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