NIST Develops Ultra-Sensitive Mini-Sensor for Biomedical and Security Applications
Researchers at the National Institute of Standards and Technology (NIST) have developed a tiny, highly sensitive magnetic sensor that could revolutionize biomedical and security applications. The new mini-sensor, described in the November issue of Nature Photonics, is capable of detecting magnetic field changes as small as 70 femtoteslas – equivalent to the brain waves of a person daydreaming.
Key Features:
– 1000x more sensitive than NIST’s original chip-scale magnetometer
– Based on spin-exchange relaxation free (SERF) principle
– Millimeter-scale, low-power design
– Potential to match sensitivity of cryogenic superconducting quantum interference devices (SQUIDs)
Applications:
– Non-invasive fetal heart monitoring
– Homeland security screening for explosives
– Magnetocardiography (MCG) and magnetoencephalography (MEG) for medical imaging
– Portable MEG helmets for epilepsy monitoring
The NIST mini-sensor consists of a single low-power infrared laser and a rice-grain-sized container with rubidium atoms. As the laser beam passes through the atomic vapor, the amount of light absorbed varies predictably with the magnetic field, providing a reference scale for measuring the field.
The device is already powerful enough for fetal heart monitoring and could be improved to detect brain activity at the 10 femtotesla level. With further development, the mini-sensor could be used in MRI systems, airport security screening, and other applications requiring high sensitivity and portability.
The NIST compact magnetometer is based on the SERF principle, which was used by a group at Princeton University in 2003 to enhance the sensitivity of larger, tabletop-sized magnetometers. The NIST group developed novel approaches and technologies to adapt the SERF concept for tiny and practical devices.
The new mini-sensor could reduce the equipment size and costs associated with some non-invasive biomedical tests, offering the advantage of not requiring contrast agents or injected tracers as do other medical procedures such as MRI or positron emission tomography (PET).
Keywords: magnetometer, femtotesla, SERF, Atomic, Metrology
