"What we are trying to do is create tiny magnetometers that are low power, yet very sensitive," says Steve Simon, executive vice president of engineering, research and development at mPhase Technologies. "We expect to combine them in arrays that will eliminate the bulky door-frame-like devices encountered at airport screening sites today." Until recently, the only way to realize high sensitivity in magnetometers to magnetic fields was with detectors cooled by liquid helium, but they are both large and expensive.

However, the new magnetometer under development employs a tiny magnet attached to a silicon crystal that exhibits a very high sensitivity, even at room temperatures. Once the magnetic field surrounding the detector changes, the tiny magnet twists a bit and exerts force on the silicon so that its natural resonance frequency changes. Electronic circuits can sense the changes in the silicon frequency and thereby detect very small changes in magnetic field strength.

The new magnetometer is about the size of the date minted on a penny coin, but can sense metal objects at distances greater than commercially available magnetometers. For detecting concealed weapons it is sensitive up to 90 feet, and in the case of a car, sensitive up to a distance of more than 450 feet. This is essential in military applications where you want to detect large objects — a car, a tank or some other vehicle — and the primary objective is safety so you want to be able to detect an object as far away from the magnetometer as possible.

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