Posted: Sep 19, 2018
(Nanowerk News) 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.
"A portable, low-cost brain imaging system that can operate at room temperature in unshielded environments would allow real-time brain activity mapping after potential concussions on the sports field and in conflict zones where the effect of explosives on the brain can be catastrophic," said researcher member Babak Amirsolaimani of the University of Arizona, Tucson.
As detailed in Optics Letters ("High sensitivity magnetometer using nanocomposite polymers with large magneto-optic response"), the researchers fabricated the magnetic sensors using optical fibers and a newly developed polymer-nanoparticle composite that is sensitive to magnetic fields. The sensors can detect the brain's magnetic field, which is 100 million times weaker than the magnetic field of earth.
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.
"The all-optical design of the sensor means it could be fabricated inexpensively on a silicon photonics chip, making it possible to produce a system that is almost as small as the sensor's 10-micron-diameter optical fiber," said Amirsolaimani. "Multiple sensors could then be used together to provide high spatial resolution brain mapping."
The new sensors could help scientists better understand the activity of the brain and diseases of the brain such as dementia and Alzheimer's. 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.