London, Nov 2 : Scientists have made a small multi-purpose sensor which can detect magnetic fields as weak as those produced by the heart of a mouse.

In fact, it can detect a field as weak as 70 femtoteslas – about a billionth of the Earth's magnetic field.

The sensor, known as an atomic magnetometer, is the size of a grain of rice. According to researchers, it can be used for a wide range of applications, from portable helmets for sensing brain activity to detectors of explosives.

About 1000 times more sensitive than previous devices of a similar size, the new device was made by John Kitching of the US National Institute of Standards and Technology in Boulder, Colorado, and colleagues.

According to Kitching, "It is not just much smaller than a SQUID (S uperconducting quantum interference device), but also operates at much higher temperatures, at around 150 °C. The small size and high performance of this sensor will open doors to applications that we could previously only dream of."

"The small size allows the sensor to get closer to the heart or brain it is measuring, and lets it run on much less power than larger atomic magnetometers or SQUIDs," said Romalis of Princeton University. "I think that it can prove to be a great combination of size and sensitivity for some applications," he added.

The research team made the new magnetometers through photolithography, the same process used to make computer chips. "You can make very large numbers of the devices in parallel on a single wafer of silicon," Kitching says. "That will reduce the cost," he adds.

Because the devices run on relatively little power, even with the laser and heating components, they could also be used for distributed sensors, Kitching says. Using a technique called nuclear quadrupole resonance that uses excited atoms to identify different molecules, they could perhaps detect explosives.

"It could be used to study people too, and could generate magnetocardiograms that provide similar information to an electrocardiogram (ECG), without requiring electrodes on the patient's body," says Kitching. "You could do it from outside clothing," he adds.

In October, Kitching and his team reported the first use of such a device for recording the magnetic field of a mouse heart. (ANI)