Diminutive doom detectors

Researchers working with the

(ONR) have developed a way to build extremely small sensors to fit on a mini-unmanned aerial vehicle (UAV) using nanorobot fabrication.

This new process, created by Harold Szu and James Buss of ONR and implemented by Xi Ning of Michigan State University, allows a human operator using a powerful microscope and hand-held controller to manipulate nanosized contact points remotely to construct the pixel elements that will form the heart of the sensor.

Each pixel will be composed of carbon nanotubes, which have nanoscale diameters and submicron lengths. Because of the one-dimensional nature of carbon nanotubes, they have significantly lower thermal noise than traditional semiconductors. A full-sized camera incorporating this technology would be inexpensive and lightweight--about one tenth the cost, weight, and size of a conventional digital camera.

The reason for making such a small sensor has to do with the largest of things--protecting multibillion-dollar aircraft carriers and their thousands of sailors. Today, missiles have become cheaper, smaller, stealthier, and more difficult to detect than ever.

To improve the ability of carrier strike groups to detect these missiles over the horizon, the US Navy is searching for ways to augment its surveillance capabilities with a covert team of mini-UAVs equipped with passive sensors that can cruise near the ocean surface at slow speeds for many hours.

One of the salient features distinguishing a missile plume from flare camouflage is the unique characteristics of a plume's IR signature, especially in the mid-IR spectrum. The signal-to-noise ratio of a conventional IR detector array operating in the ocean environment, however, demands the use of cumbersome liquid nitrogen cryogenic cooling for all current mid-IR spectrum cameras. Unfortunately, a mini-UAV's payload limitation does not allow such a bulky technology on board but a small UAV is possible with the advent of nanobased sensors.