WASHINGTON -- Researchers have developed a light-based technique for measuring very weak magnetic fields, such as those produced when neurons fire in the brain.

The inexpensive and compact sensors could offer an alternative to the magnetic resonance imaging (MRI) systems currently used to map brain activity without the expensive cooling or electromagnetic shielding required by MRI machines.

As detailed in The Optical Society (OSA) journal Optics Letters, the researchers fabricated the magnetic sensors using optical fibers and a newly developed polymer-nanoparticle composite that is sensitive to magnetic fields.

The researchers also showed that the new sensor can detect the weak magnetic pattern of a human heartbeat and has the capability to detect magnetic fluctuations that change every microsecond from an area as small as 100 square microns.

They might also be useful for measuring the magnetic fields used to predict volcanic eruptions and earthquakes, identify oil and minerals for excavation and detect military submarines.

Optical detection of magnetic fields

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