Alien hunters devise world's smallest microphone

Can hear a single cell growing

Researchers at NASA's Jet Propulsion Laboratory claim to have devised the most sensitive listening device ever. Designed to enable robot explorers to listen out for life on other planets, the tiny microphone could theoretically detect the sound of a single cell growing.

The device, currently known as a "nanomicrophone" [Although that does seem a bit excessive to us - Ed.] does not depend on a membrane to detect vibrations, rather it based on stereocilla, the tiny hairs that line the inner ear and transmit sound to the brain.

The artificial cilla are made from carbon nanotubes, which bend in response to the slightest change in pressure.

The research team leader, Flavio Noca, commented: "There's a whole world buzzing down there. Movement is one of the signatures for life." He said in an interview with Business Week: "I found that flat acoustic membranes would never do the job of sensing nanoscale movements. That's how I came up with the idea of using protruding rods."

Although the nanophone was developed as part of the search for ET, it could have many other applications. Noca suggests that it could eventually be used to detect tumours when they are only a few cells wide. "It's known that the intracellular activity of cancerous cells tends to be much higher than for healthy cells. A nanoexplorer loaded with a nanostethoscope could probably "hear" such cells," he noted.

The device could also be useful in hearing aids because of its directional sensitivity. He said that it would also have military applications, such as a covert listening device or it could be put to use by the navy. "It's still not well understood how fish detect prey with lateral lines, [lines of cilla along the side of a fish's body - Ed] but the Navy would be very interested in having a similar device to detect foreign objects in the ocean in a passive way," he said.

All this is still a long way off, however, and for now Noca says his aim is to produce a working device that meets expectations. ®

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