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Chip-Scale Atomic Magnetometer

Patent Number: 8,334,690


A magnetometer and method of use is presently disclosed. The magnetometer has at least one sensor void of extraneous metallic components, electrical contacts and electrically conducting pathways. The sensor contains an active material vapor, such as an alkali vapor, that alters at least one measurable parameter of light passing therethrough, when in a magnetic field. The sensor may have an absorptive material configured to absorb laser light and thereby activate or heat the active material vapor. 


Fiber magnetometer
Credit: NIST

Measurement of faint magnetic fields is critical to many applications, notably including medical diagnostics, but conventional technologies are often large, complex and expensive. 

NIST’s chip-scale atomic magnetometer, by contrast, is highly compact and readily fabricated using familiar semiconductor techniques. It employs small beams of circularly polarized laser light passing through a millimeter-sized chamber containing a vapor of alkali atoms. The presence of a magnetic field alters the spin orientation of the atoms; that in turn changes the polarization of the outgoing laser beam, which is detected optically. The magnitude of the change is a sensitive measure of field strength.


Diagnosis with magnetometers can detect fields caused by electrical currents in the brain and heart that are predictive of epilepsy, cardiac dysfunction and other conditions. For the brain, conventional technologies employed are electroencephalography, in which electrodes are placed directly on the patient’s skull, and magnetoencephalography in which superconducting sensors called SQUIDs are cooled to 4 degrees above absolute zero and placed at some distance above the skull. Magnetic fields from brain waves, which are feeble to begin with, decrease with distance to the sensor.

The NIST chip-scale magnetometer operates slightly above room temperature and does not directly touch the skull. It is also completely passive, sensing the brain fields without disturbing the brain in any way.

High sensitivity based on quantum science.


  • Highly sensitive; can measure fields of a few femtotesla (10-15 T), more than a billion times fainter than Earth’s field
  • Small size
  • Low power requirement
  • Manufacturable with existing technology
  • Potentially mobile


  • Medical diagnostics
  • Detection of transport of magnetic nanoparticles for imaging and flow measurement
  • Standoff detection of submarines, vehicles, and aircraft  
  • Magnetic measurements in space for planetary science and solar weather
  • Measurement of geomagnetic fields for oil and mineral exploration 


The NIST chip-scale atomic magnetometer provides a low-power, quantum-based technology to replace legacy instruments. It can have a strong appeal to users of medical diagnostic equipment, firms that conduct geophysical mapping and underground deposit, operators of underwater navigation equipment, and organizations involved in space science.


  • Opportunity for multiple collaborative development relationships with research and development
  • Cooperative Research and Development Agreements (CRADA)
  • Patent License Agreements (PLAs)

See also: Patent No. 6,806,784

Miniature frequency standard based on all-optical excitation and a micro-machined containment vessel

Created March 13, 2020, Updated February 11, 2021